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https://en.wikipedia.org/wiki/Beetle
JBS Haldane said when asked by a theologian "what can we infer from the mind of he creator by his creation". Haldane is a very famous biologist. He said "he has an inordinate fondness of beatles" because beatles are the most diverse species. However there are four orders of beatles so Aldane was correct, the quadrant model can be seen through them. There was a fifth order but it went extinct. The fifth is always questionable. They are
Adephaga
Archostemata
Myxophaga
Polyphaga
† Protocoleoptera
Many beetles were prominent in ancient cultures.[78] Of these, the most prominent might be the dung beetle in Ancient Egypt. Several species of dung beetle, most notably the species Scarabaeus sacer (often referred to as the sacred scarab), enjoyed a sacred status among the ancient Egyptians.[79] Popular interpretation in modern academia theorizes the hieroglyphic image of the beetle represents a triliteral phonetic that Egyptologists transliterate as xpr or ḫpr and translate as "to come into being", "to become", or "to transform".
And the fourth order is different from the other three.
The scarab was linked to Khepri ("he who has come into being"), the god of the rising sun. The ancients believed the dung beetle was only male in gender, and reproduced by depositing semen into a dung ball. The supposed self-creation of the beetle resembles that of Khepri, who created himself out of nothing. Moreover, the dung ball rolled by a dung beetle resembles the sun.
It is no coincidence the group representing becoming (the 19th square) reflects the quadrant pattern
https://en.wikipedia.org/wiki/Beetle
Cockroaches are insects of the order Blattodea, which also includes termites. About 30 cockroach species out of 4,600 are associated with human habitats. About four species are well known as pests.
http://www.meta-synthesis.com/webbook/38_laing/tetrahedra.html
Laing's 1993 Tetrahedron of Bonding
In 1993 Michael Laing published an expansion of the two dimensional van Arkel-Ketelaar triangle of bonding into a tetrahedron by dividing covalent materials into two types, Covalent Network and van der Waals Molecular: M. Laing, A Tetrahedron of Bonding, Education in Chemistry, November, pp160-163
http://www.meta-synthesis.com/webb…/38_laing/tetrahedra.html
The Grimm Tetrahedron (1928, but rather forgotten)
William Jensen reports, below, that Grimm and Dehlinger developed an early form of tetrahedron in the nineteen thirties. However, this knowledge appears to have been forgotten. The Grimm Tetrahedron symbolically reflects with the four vertices of a tetrahedron the four main types of bonding in solid chemical compounds: metallic (metallisch), ionic (heteropolar), van der Waals (molecular) & network (homopolar).
From William B. Jensen's paper: Logic, History, and the Chemistry Textbook, J.Chem.Educ. 817-828, 75, 1998:
Dehlinger's 1934 drawing of Grimm's tetrahedron:
Grimm’s two-dimensional projection of his 1934 bond- type tetrahedron redrawn by Jensen using corrected and updated examples:
i = Ionenbindung
a = Atombindung
m = metallische Bindung
z = zwischenmolekulare Kräfte
The six edges between these vertices correspond to the intermediate types of bonds. It is clear that the idea of isolated molecules can be most naturally applied only to one vertex of this diagram (the central one, where the intermolecular interactions are the weak van der Waals forces).
From the Concept of Chemical Periodicity: from Mendeleev Table to Molecular Hyper-Periodicity Patterns E. V. Babaev & Ray Hefferlin, here.
http://www.meta-synthesis.com/webb…/38_laing/tetrahedra.html
https://en.wikipedia.org/wiki/Allagash_Abductions
Brothers Jim Weiner and Jack Weiner with friends Charles Foltz and Charles Rak claim that they were abducted by aliens during a camping trip in Allagash, Maine on August 20, 1976. According to the four men, hypnotic regression enabled them to recall being taken aboard a circular UFO and being "probed and tested by four-fingered beings with almond-shaped eyes and languid limbs". The first two were twins and are the duality. The fourth actually ended up kind of questioning the experience. The fourth is always different.
Protein quaternary structure
From Wikipedia, the free encyclopedia
The image above contains clickable linksInteractive diagram of protein structure, using PCNA as an example. (PDB: 1AXC)
Protein quaternary structure is the number and arrangement of multiple folded protein subunits in a multi-subunit complex. It includes organisations from simple dimers to large homooligomers and complexes with defined or variable numbers of subunits.[1] It can also refer to biomolecular complexes of proteins with nucleic acids and other cofactors.
https://en.wikipedia.org/wiki/Protein_quaternary_structure
https://en.wikipedia.org/wiki/Protein_tertiary_structure
The quaternary structure- the fourth, is different
https://en.wikipedia.org/wiki/Proteasome
In structure, the proteasome is a cylindrical complex containing a "core" of four stacked rings forming a central pore. Each ring is composed of seven individual proteins. The inner two rings are made of seven β subunits that contain three to seven protease active sites. These sites are located on the interior surface of the rings, so that the target protein must enter the central pore before it is degraded. The outer two rings each contain seven α subunits whose function is to maintain a "gate" through which proteins enter the barrel. These α subunits are controlled by binding to "cap" structures or regulatory particles that recognize polyubiquitin tags attached to protein substrates and initiate the degradation process. The overall system of ubiquitination and proteasomal degradation is known as the ubiquitin-proteasome system.[3]
proteasome (four heptameric rings = 28 subunits)
There is one 20s particle.All 20S particles consist of four stacked heptameric ring structures that are themselves composed of two different types of subunits; α subunits are structural in nature, whereas β subunits are predominantly catalytic.
There are two 19s particles.
There is one 11s particle. The fourth is different
https://en.wikipedia.org/wiki/Homotetramer
A homotetramer is a protein complex made up of four identical subunits which are associated but not covalently bound.[1] A heterotetramer is a 4-subunit complex where one or more subunits differ.[2]
Examples of homotetramers include:
enzymes like beta-glucuronidase (pictured)
export factors such as SecB from Escherichia coli[3]
magnesium ion transporters such as CorA.[4]
lectins such as Concanavalin A
https://en.wikipedia.org/wiki/Homotetramer
Beta-glucuronidases are members of the glycosidase family of enzymes that catalyze breakdown of complex carbohydrates.[2] Human β-glucuronidase is a type of glucuronidase (a member of glycosidase Family 2) that catalyzes hydrolysis of β-D-glucuronic acid residues from the non-reducing end of mucopolysaccharides (also referred to as glycosaminoglycans) such as heparan sulfate.[2][3][4] Human β-glucuronidase is located in the lysosome.[5] In the gut, brush border β-glucuronidase converts conjugated bilirubin to the unconjugated form for reabsorption. Beta-glucuronidase is also present in breast milk, which contributes to neonatal jaundice. The protein is encoded by the GUSB gene.[6][7]
https://en.wikipedia.org/…/File:Beta-Glucuronidase_Homotetr…
https://en.wikipedia.org/wiki/Homotetramer
A homotetrameric complex, beta-glucuronidase (a glycosidase). Each subunit has the same amino acid sequence.
http://antoine.frostburg.edu/…/…/faq/antoines-elements.shtml
Lavoisier is considered the "Father of chemistry". He was the first chemist to recognize that the air earth fire and water model of the four elements was not suitable for describing the elements of nature (although those who understand the quadrant model know that metaphorically it did describe reality). He is the first person to isolate oxygen and other elements and recognize that the four elements themselves were made of other elements.
He classified the known elements into four groups:
Elastic fluids
Lavoisier included light, heat, oxygen, nitrogen, and hydrogen in this group.
Nonmetals
This group includes "oxidizable and acidifiable nonmetallic elements". Lavoisier lists sulfur, phosphorus, carbon, hydrochloric acid, hydrofluoric acid, and boric acid.
Metals
These elements are "metallic, oxidizable, and capable of neutralizing an acid to form a salt." They include antimony and arsenic (which are not considered metals today), silver, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdenum, nickel, gold, platinum, lead, tungsten, and zinc.
Earths
Lavoisier's salt-forming earthy solid "elements" included lime, magnesia (magnesium oxide), baryta (barium oxides), alumina (aluminum oxide), and silica (silicon dioxide).
This was a huge leap forward in chemistry and a realization that there was order to the elements and grand pattern to the building blocks of reality. Although the way he classified them is now considered incorrect.
This was the first modern classification of elements from which modern chemistry evolved. It fit the quadrant model pattern.
http://antoine.frostburg.edu/…/…/faq/antoines-elements.shtml
https://en.wikipedia.org/wiki/Atlantic_horseshoe_crab
There are four species of horseshoe crab.
Horseshoe crabs were traditionally grouped with the extinct eurypterids (sea scorpions) as the Merostomata. They may have evolved in the shallow seas of the Paleozoic Era (570–248 million years ago) with other primitive arthropods like the trilobites. The four species of horseshoe crab are the only remaining members of the Xiphosura, one of the oldest classes of marine arthropods.
The Atlantic horseshoe crab (Limulus polyphemus) is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs.[2] Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America. A main area of annual migration is Delaware Bay, although stray individuals are occasionally found in Europe.[3]
The other three extant species in the family Limulidae are also called horseshoe crabs.[4] These are Tachypleus tridentatus, Tachypleus gigas and Carcinoscorpius rotundicauda, which all are restricted to Asia.[4][5] All four are quite similar in form and behavior.
In 1956, Hartline revisited this concept of lateral inhibition in horseshoe crab (Limulus polyphemus) eyes, during an experiment conducted with the aid of Henry G Wagner and Floyd Ratliff. Hartline explored the anatomy of ommatidia in the horseshoe crab because of their similar function and physiological anatomy to photoreceptors in the human eye.
https://en.wikipedia.org/wiki/Spider
Mesothelae- spinnerets. Four pairs, in some species one pair fused, under middle of abdomen.
Spiders have primarily four pairs of eyes on the top-front area of the cephalothorax, arranged in patterns that vary from one family to another
Spiders also have four pairs of legs.
Tetrahymena are free-living ciliate protozoa that can also switch from commensalistic to pathogenic modes of survival. They are common in freshwater ponds. Tetrahymena species used as model organisms in biomedical research are T. thermophila and T. pyriformis. Tetra hymena means four membrane.
Tetrahymena possess hundreds of cilia and has complicated microtubule structures, making it an optimal model to illustrate the diversity and functions of microtubule arrays.
Tetra means four. They have four nuclei.
Studies on Tetrahymena have contributed to several scientific milestones including:
First cell which showed synchronized division, which led to the first insights into the existence of mechanisms which control the cell cycle.[3]
Identification and purification of the first cytoskeleton based motor protein such as dynein.[3]
Aid in the discovery of lysosomes and peroxisomes.[3]
Early molecular identification of somatic genome rearrangement.[3]
Discovery of the molecular structure of telomeres, telomerase enzyme, the templating role of telomerase RNA and their roles in cellular senescence and chromosome healing (for which a Nobel Prize was won).[3]
Nobel Prize–winning co-discovery (1989, in Chemistry) of catalytic ribonucleic acid (ribozyme).[3]
Discovery of the function of histone acetylation.[3]
Demonstration of the roles of posttranslational modification such as acetylation and glycylation on tubulins and discovery of the enzymes responsible for some of these modifications (glutamylation)
Crystal structure of 40S ribosome in complex with its initiation factor eIF1
First demonstration that two of the "universal" stop codons, UAA and UAG, will code for the amino acid glutamine in some eukaryotes, leaving UGA as the only termination codon in these organisms. [4]
Discovery of self-splicing RNA. [5]
https://en.wikipedia.org/wiki/Sponge
The fourth is always different
Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, is actually phylogenetically well separated. Therefore, they have recently been recognized as the fourth class of sponges.[26][27]
QMR
https://simple.wikipedia.org/wiki/File:Griffith_experiment.svg
https://simple.wikipedia.org/wiki/Griffith's_experiment
Griffith's experiment, reported in 1928 by Frederick Griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation. This experiment was revolutionary to the discovery of DNA and gene transference. The experiment fit the quadrant model pattern.
Griffith tried four things.
Square 1: He injected a mouse with a non virulent bacteria and it lived
Square 2: He injected a mouse with a virulent bacteria and it died
Square 3: He injected the mouse with the virulent bacteria and heated it thinking it would kill the virulent part of the bacteria and the mouse lived
Square 4: This was the transcendent square and was the shock of the experiment which lead to the revelation. The fourth square is always transcendent. Griffith then injected the mouse with the heated virulent bacteria and the non virulent bacteria. Since both of them had not killed the mouse he thought the mouse would survive. But he found that the mouse died and he found deadly bacteria in their blood. This means that the genes of the bacteria must have carried the DNA although Griffith did not know this and it took until the discovery of genes for this to be understood. He discovered something in the heated bacteria survived and transformed into killer cells. He had discovered genes and gene transfer.
This experiment is one of the most legendary experiments in biology history. It is no coincidence that the quadrant model is reflected.
https://simple.wikipedia.org/w…/File:Griffith_experiment.svg
https://simple.wikipedia.org/wiki/Griffith's_experiment
Griffith's experiment, reported in 1928 by Frederick Griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation. This experiment was revolutionary to the discovery of DNA and gene transference. The experiment fit the quadrant model pattern.
Griffith tried four things.
Square 1: He injected a mouse with a non virulent bacteria and it lived
Square 2: He injected a mouse with a virulent bacteria and it died
Square 3: He injected the mouse with the virulent bacteria and heated it thinking it would kill the virulent part of the bacteria and the mouse lived
Square 4: This was the transcendent square and was the shock of the experiment which lead to the revelation. The fourth square is always transcendent. Griffith then injected the mouse with the heated virulent bacteria and the non virulent bacteria. Since both of them had not killed the mouse he thought the mouse would survive. But he found that the mouse died and he found deadly bacteria in their blood. This means that the genes of the bacteria must have carried the DNA although Griffith did not know this and it took until the discovery of genes for this to be understood. He discovered something in the heated bacteria survived and transformed into killer cells. He had discovered genes and gene transfer.
This experiment is one of the most legendary experiments in biology history. It is no coincidence that the quadrant model is reflected.
https://en.wikipedia.org/wiki/Cytokine
Structural[edit]
Structural homogeneity has been able to partially distinguish between cytokines that do not demonstrate a considerable degree of redundancy so that they can be classified into four types:
The four-α-helix bundle family: member cytokines have three-dimensional structures with four bundles of α-helices. This family, in turn, is divided into three sub-families:
the IL-2 subfamily
the interferon (IFN) subfamily
the IL-10 subfamily.
The first of these three, the IL-2 subfamily, is the largest. It contains several non-immunological cytokines including erythropoietin (EPO) and thrombopoietin (TPO). Furthermore, four-α-helix bundle cytokines can be grouped into long-chain and short-chain cytokines.[citation needed]
the IL-1 family, which primarily includes IL-1 and IL-18
the IL-17 family, which has yet to be completely characterized, though member cytokines have a specific effect in promoting proliferation of T-cells that cause cytotoxic effects.
the cysteine-knot cytokines include members of the transforming-growth-factor-beta superfamily, including TGF-β1, TGF-β2 and TGF-β3.
The four-α-helix bundle family: member cytokines have three-dimensional structures with four bundles of α-helices.
https://en.wikipedia.org/wiki/Mechanoreceptor
A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous mammalian skin: lamellar corpuscles, tactile corpuscles, Merkel nerve endings, and bulbous corpuscles. There are also mechanoreceptors in hairy skin, and the hair cells in thoreceptors of primates like rhesus monkeys and other mammals are similar to those of humans and also studied even in early 20th century anatomically and neurophysiologically.[1]
https://en.wikipedia.org/wiki/Unhappy_triad
The medial collateral ligament, posterior cruciate ligament, anterior cruciate ligament, and lateral collateral ligament are the four primary ligaments of the knee
https://www.strengthandconditioningresearch.com/muscles/hamstrings/
The fourth is different and often not mentioned
The hamstrings are a group of four muscles on the back of the thigh. Three of them are two-joint muscles (performing both knee flexion and hip extension) while the fourth performs only knee flexion. As a group, the hamstrings can therefore be trained by exercises that involve either hip extension or knee flexion.
The four hamstrings muscles are: the biceps femoris (long head), the biceps femoris (short head), the semitendinosus, and the semimembranosus. The two biceps femoris muscles are located on the lateral part of the thigh. The semitendinosus and the semimembranosus are located on the medial part of the thigh.
https://en.wikipedia.org/wiki/Ventricular_system
The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. The ventricular system is continuous with the central canal of the spinal cord (from the fourth ventricle) allowing for the flow of CSF to circulate. All of the ventricular system and the central canal of the spinal cord is lined with ependyma, a specialised form of epithelium.
https://en.wikipedia.org/wiki/Bothrops_asper
Some of the common names applied to this snake are terciopelo, fer-de-lance,[2] barba amarilla (Guatemala, Honduras; "yellow beard"), equis (Ecuador & Panama; "x"),[5] taya equis (Colombia), cuaima (Venezuela), nauyaca (México; from Nahuatl nahui, four, and yacatl, nose; "four noses"),[6] and yellow-jaw tommygoff (Belize).
https://en.wikipedia.org/wiki/Basal_ganglia
In terms of anatomy, the basal ganglia are divided by anatomists into four distinct structures, depending on how superior or rostral they are (in other words depending on how close to the top of the head they are): Two of them, the striatum and the pallidum, are relatively large; the other two, the substantia nigra and the subthalamic nucleus, are smaller. In the illustration to the right, two coronal sections of the human brain show the location of the basal ganglia components. Of note, and not seen in this section, the subthalamic nucleus and substantia nigra lie farther back (posteriorly) in the brain than the striatum and pallidum.
https://en.wikipedia.org/wiki/Aulus_Cornelius_Celsus
Aulus Cornelius Celsus (c. 25 BC – c. 50 AD) was a Roman encyclopaedist, known for his extant medical work, De Medicina, which is believed to be the only surviving section of a much larger encyclopedia. The De Medicina is a primary source on diet, pharmacy, surgery and related fields, and it is one of the best sources concerning medical knowledge in the Roman world.
Aulus Cornelius Celsus is credited with recording the cardinal signs of inflammation known as "Celsus tetrad": calor (warmth), dolor (pain), tumor (swelling) and rubor (redness and hyperaemia). He goes into great detail regarding the preparation of numerous ancient medicinal remedies including the preparation of opioids. In addition, he describes many 1st century Roman surgical procedures which included removal of a cataract, treatment for bladder stones, and the setting of fractures.
https://en.wikipedia.org/wiki/Chiasma_(genetics)
Chiasma means cross
A chiasma (plural: chiasmata), in genetics, is thought to be the point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis (sister chromatids also form chiasmata between each other (also known as a chi structure), but because their genetic material is identical, it does not cause any change in the resulting daughter cells). The chiasmata become visible during the diplotene stage of prophase I of meiosis, but the actual "crossing-over" of genetic material is thought to occur during the previous pachytene stage. When each tetrad, which is composed of two pairs of sister chromatids, begins to split, the only points of contact are at the chiasmata.
Chiasma means cross
Chiasm means cross
https://en.wikipedia.org/wiki/Optic_chiasm
The optic chiasm or optic chiasma (pronunciation: /ɒptɪk kaɪæzəm/; Greek χίασμα, "crossing", from the Greek χιάζω 'to mark with an X', after the Greek letter 'Χ', chi) is the part of the brain where the optic nerves partially cross. The optic chiasm is located at the bottom of the brain immediately below the hypothalamus.[1] The optic chiasm is found in all vertebrates, although in cyclostomes (lampreys and hagfishes) it is located within the brain.[2] [3]
https://en.wikipedia.org/wiki/Meiosis
Tetrad is another word for chromosomes, which carry genetic information for all creatures. It is no coincidence they resemble the quadrant.
Prophase I is typically the longest phase of meiosis. During prophase I, homologous chromosomes pair and exchange DNA in a process called homologous recombination. This often results in chromosomal crossover. This process is critical for pairing between homologous chromosomes and hence for accurate segregation of the chromosomes at the first meiosis division. The new combinations of DNA created during crossover are a significant source of genetic variation, and result in new combinations of alleles, which may be beneficial. The paired and replicated chromosomes are called bivalents or tetrads, which have two chromosomes and four chromatids, with one chromosome coming from each parent. The process of pairing the homologous chromosomes is called synapsis. At this stage, non-sister chromatids may cross-over at points called chiasmata (plural; singular chiasma).[10] Prophase I has historically been divided into a series of substages which are named according to the appearance of chromosomes
https://en.wikipedia.org/wiki/Meiosis
Four cells are created, one is different.
Meiosis Listeni/maɪˈoʊsᵻs/ is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.[1] This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.[2][3][4][5] Errors in meiosis resulting in aneuploidy are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities.[6]
In meiosis, DNA replication is followed by two rounds of cell division to produce four potential daughter cells, each with half the number of chromosomes as the original parent cell. The two meiotic divisions are known as Meiosis I and Meiosis II. Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated so that it consists of two identical sister chromatids, which remain held together through sister chromatid cohesion. This S-phase can be referred to as "premeiotic S-phase" or "meiotic S-phase." Immediately following DNA replication, meiotic cells enter a prolonged G2-like stage known as meiotic prophase. During this time, homologous chromosomes pair with each other and undergo genetic recombination, a programmed process in which DNA is cut and then repaired, which allows them to exchange some of their genetic information. A subset of recombination events results in crossovers, which create physical links known as chiasmata (singular: chiasma, for the Greek letter Chi (X)) between the homologous chromosomes. In most organisms, these links are essential to direct each pair of homologous chromosomes to segregate away from each other during Meiosis I, resulting in two haploid cells that have half the number of chromosomes as the parent cell. During Meiosis II, the cohesion between sister chromatids is released and they segregate from one another, as during mitosis. In some cases all four of the meiotic products form gametes such as sperm, spores, or pollen. In female animals, three of the four meiotic products are typically eliminated by extrusion into polar bodies, and only one cell develops to produce an ovum.
In females "three of the four meiotic products are eliminated"- "one of the four becomes the ovum"
https://en.wikipedia.org/wiki/Tetrad_(genetics)
The tetrad is the four spores of a yeast, other Ascomycota or Chlamydomonas produced after meiosis. After parent haploids mate, they produce diploids. Under appropriate environmental conditions, diploids sporulate and undergo meiosis. The meiotic products, spores, remain packaged in the parental cell body to produce the tetrad. If the two parents have a mutation in two different genes, the tetrad can segregate these genes as the parental ditype (PD), the non-parental ditype (NPD) or as the tetratype (TT).[1]
https://en.wikipedia.org/wiki/Tetrad_(genetics)
Tetrad analysis can be used to confirm whether a phenotype is caused by a specific mutation, construction of strains, and for investigating gene interaction. Since the frequency of tetrad segregation types is influenced by the recombination frequency for the two markers, the segregation data can be used to calculate the genetic distance between the markers if they are close on the same chromosome. Tetrad analyses have also contributed to detection and study of the phenomena of gene conversion and post-meiotic segregation.[2] These studies have proven central to understanding the mechanism of meiotic recombination, which in turn is a key to understanding the adaptive function of sexual reproduction. The use of tetrads in fine-structure genetic analysis is described in the articles Neurospora crassa and Gene conversion.
General procedure[edit]
Crosses are performed between haploid MATa and MATα mating strains, then the resulting diploids are transferred to sporulation media to form a tetrad containing four haploid spores. Tetrads can then be prepared with Zymolyase, or another enzyme, to digest the wall of the ascus. The spores are then separated with a micromanipulator needle and deposited in separate positions on a petri dish.
Tools[edit]
Traditionally, tetrad dissection has a reputation as "dark art".[3] However, instruments have since been developed specifically for tetrad dissection; the most advanced allow easy and semi-automated separation of tetrads [2] . Most micromanipulators use a glass fiber needle to which the spores adhere due to the formation of a water meniscus between the agar and the needle.
https://en.wikipedia.org/wiki/History_of_horse_domestication_theories
A theory associated with James Cossar Ewart in Scotland and Johann Ulrich Duerst in Germany postulated three primitive horse types, considered subspecies of Equus caballus, as ancestors of modern breeds of horse. They were:[4]
Square 1: "Forest Horse", Equus caballus germanicus, descendant of a "Diluvial Horse", Equus caballus silvaticus
Square 2: Asiatic Wild Horse or Przewalski horse, then considered Equus caballus przewalskii
Square 3: Tarpan, then considered Equus caballus gmelini.
Square 4: To these Elwyn Hartley Edwards adds a fourth, the "Tundra Horse", supposedly ancestor of the Yakut pony, and "largely unconsidered by hippologists".
https://en.wikipedia.org/wiki/List_of_horse_breeds
The horse is the animal whose family tree is known to the highest precision by biologists.
Before the availability of DNA techniques to resolve the questions related to the domestication of the horse, various hypothesis were proposed. One classification was based on body types and conformation, suggesting the presence of four basic prototypes, labeled the "Tarpan", "Forest horse", Draft and "Oriental", each of which was hypothesized to have adapted to their environment prior to domestication. However, more recent studies suggest that all domesticated horses originated from a single wild species and that the different body types of horses were entirely a result of selective breeding after domestication,[3] or possibly landrace adaptation.
Before the availability of DNA techniques to resolve the questions related to the domestication of the horse, various hypotheses were proposed. One classification was based on body types and conformation, suggesting the presence of four basic prototypes that had adapted to their environment prior to domestication. Another hypothesis held that the four prototypes originated from a single wild species and that all different body types were entirely a result of selective breeding after domestication. However, the lack of a detectable substructure in the horse has resulted in a rejection of both hypotheses
16 is the squares of the quadrant model. The comet presented a 12 plus four pattern, which is the quadrant modle pattern. I studied comet landings and all sorts of stuff and saw the quadrant model everywhere, but can't remember a lot of it now
Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals.[30][31] Further, the ALICE spectrograph on Rosetta determined that electrons (within 1 km (0.62 mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[32][33] Instruments on the Philae lander found at least sixteen organic compounds at the comet's surface, four of which (acetamide, acetone, methyl isocyanate and propionaldehyde) have been detected for the first time on a comet
https://en.wikipedia.org/wiki/Kangaroo
The kangaroo /ˌkæŋɡəˈruː/ is a marsupial from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, especially those of the genus Macropus: the red kangaroo, antilopine kangaroo, eastern grey kangaroo, and western grey kangaroo. Kangaroos are endemic to Australia. The Australian government estimates that 34.3 million kangaroos lived within the commercial harvest areas of Australia in 2011, up from 25.1 million one year earlier.
There are four species that are commonly referred to as kangaroos:
The red kangaroo (Macropus rufus) is the largest surviving marsupial anywhere in the world. The Red Kangaroo occupies the arid and semi-arid centre of the country. The highest population densities of the Red Kangaroo occur in the rangelands of western New South Wales. Red kangaroos are commonly mistaken as the most abundant species of kangaroo, but eastern greys actually have a larger population.[18] A large male can be 2 metres (6 ft 7 in) tall and weigh 90 kg (200 lb).[19]
The eastern grey kangaroo (Macropus giganteus) is less well-known than the red (outside Australia), but the most often seen, as its range covers the fertile eastern part of the country. The range of the Eastern Grey Kangaroo extends from the top of the Cape York Peninsula in north Queensland down to Victoria, as well as areas of south-eastern Australia and Tasmania. Population densities of Eastern Grey Kangaroos usually peak near 100 per km2 in suitable habitats of open woodlands. Populations are more limited in areas of land clearance, such as farmland, where forest and woodland habitats are limited in size or abundance.[18]
The western grey kangaroo (Macropus fuliginosus) is slightly smaller again at about 54 kg (119 lb) for a large male. It is found in the southern part of Western Australia, South Australia near the coast, and the Darling River basin. The highest population densities occur in the western Riverina district of New South Wales and in western areas of the Nullarbor Plain in Western Australia. Populations may have declined, particularly in agricultural areas. The species has a high tolerance to the plant toxin sodium fluoroacetate, which indicates a possible origin from the south-west region of Australia.[18]
The antilopine kangaroo (Macropus antilopinus) is, essentially, the far-northern equivalent of the eastern and western grey kangaroos. It is sometimes referred to as the ‘Antilopine Wallaroo,’ but in behaviour and habitat it is more similar to Red and grey kangaroos. Like them, it is a creature of the grassy plains and woodlands, and gregarious. Their name comes from their fur, which is similar in colour and texture to that of antelopes. Characteristically, the noses of males swell behind the nostrils. This enlarges nasal passages and allows them to release more heat in hot and humid climates
https://en.wikipedia.org/…/2010_Sharm_El_Sheikh_shark_attac…
The 2010 Sharm el-Sheikh shark attacks were a series of attacks by sharks on swimmers off the Red Sea resort of Sharm el-Sheikh, Egypt. On 1 December 2010, three Russians and one Ukrainian were seriously injured within minutes of each other. This was the first four squares. The fourth was different. After this the beaches were closed for a long time and authorities went on a killing spree killing all of the sharks that they could find in the area. Then the beaches were reopened and right when they were reopeneda 5 December 2010 a German woman was killed, when they were attacked while wading or snorkeling near the shoreline. The attacks were described as "unprecedented" by shark experts. It was seen as bizarre as nothing like that had ever happened before. The fifth is always ultra transcendent the fourth is always different.
In response to the attacks, beaches in the popular tourist resort were closed for over a week, dozens of sharks were captured and killed, and the local government issued new rules banning shark feeding and restricting swimming. A variety of theories were put forward to explain the attacks. By late December 2010, the most plausible theory to emerge was that the dumping of sheep carcasses in the Red Sea by a livestock transport during the Islamic festival of Eid al-Adha had attracted the sharks to the shore. Other theories focused on overfishing in the Red Sea or on the illegal or inadvertent feeding of sharks or smaller fish close to the shore, which produced scents that attracted more sharks.
The attacks fit the quadrant model pattern.
The attacks also sparked conspiracy theories about possible Israeli involvement. Egyptian television broadcast claims that Israeli divers captured a shark with a GPS unit planted on its back. Describing the theory as "sad", Professor Mahmoud Hanafy of the Suez Canal University pointed out that GPS devices are used by marine biologists to track sharks, not to remote-control them. Governor Mohamed Abdel Fadil Shousha himself ultimately said he thought the dumping of sheep carcasses during the Islamic festival of Eid al-Adha on 16 November was the most likely explanation.
These are the two very famous shark attack sprees and they fit the quadrant model pattern.
https://en.wikipedia.org/wiki/Le_Règne_Animal
From the website quadriformisratio
Cuvier's most admired work was his Le Règne Animal. It appeared in four octavo volumes in 1817; a second edition in five volumes was brought out in 1829–1830. In this classic work, Cuvier presented the results of his life's research into the structure of living and fossil animals. With the exception of the section on insects, in which he was assisted by his friend Latreille, the whole of the work was his own. It was translated into English many times, often with substantial notes and supplementary material updating the book in accordance with the expansion of knowledge
For the Règne Animal, using evidence from comparative anatomy and palaeontology—including his own observations—Cuvier divided the animal kingdom into four principal body plans. Taking the central nervous system as an animal's principal organ system which controlled all the other organ systems such as the circulatory and digestive systems, Cuvier distinguished four types of organisation of an animal's body:
I. with a brain and a spinal cord (surrounded by parts of the skeleton)
II. with organs linked by nerve fibres
III. with two longitudinal, ventral nerve cords linked by a band with two ganglia positioned below the oesophagus
IV. with a diffuse nervous system which is not clearly discernible
Grouping animals with these body plans resulted in four "embranchements" or branches (vertebrates, molluscs, the articulata that he claimed were natural (arguing that insects and annelid worms were related) and zoophytes (radiata)). This effectively broke with the mediaeval notion of the continuity of the living world in the form of the great chain of being. It also set him in opposition to both Saint-Hilaire and Lamarck: Lamarck claimed that species could transform through the influence of the environment, while Saint-Hilaire argued in 1820 that two of Cuvier's branches, the molluscs and radiata, could be united via various features, while the other two, articulata and vertebrates, similarly had parallels with each other. Then in 1830, Saint-Hilaire argued that these two groups could themselves be related, implying a single form of life from which all others could have evolved, and that Cuvier's four body plans were not fundamental.
The classification adopted by Cuvier to define the natural structure of the animal kingdom, including both living and fossil forms,[17] was as follows, the list forming the structure of the Règne Animal. Where Cuvier's group names correspond (more or less) to modern taxa, these are named, in English if possible, in parentheses. The table from the 1828 Penny Cyclopaedia indicates species that were thought to belong to each group in Cuvier's taxonomy.
I. Vertébrés. (Vertebrates)
Mammifères (Mammals): 1. Bimanes, 2. Quadrumanes, 3. Carnassiers (Carnivores), 4. Rongeurs (Rodents), 5. Édentés (Edentates), 6. Pachydermes (Pachyderms), 7. Ruminants (Ruminants), 8. Cétacés (Cetaceans).
Oiseaux (Birds): 1. Oiseaux de proie (Birds of prey), 2. Passereaux (Passerines), 3. Grimpeurs (Piciformes), 4. Gallinacés (Gallinaceous birds), 5. Échassiers (Waders), 6. Palmipèdes (Anseriformes).
Reptiles (Reptiles, inc. Amphibians): 1. Chéloniens (Chelonii), 2. Sauriens (Lizards), 3. Ophidiens (Snakes), 4. Batraciens (Amphibians).
Poissons (Fishes): 1. Chrondroptérygiens à branchies fixes (Chondrichthyes), 2. Sturioniens ou Chrondroptérygiens à branchies libres (Sturgeons), 3. Plectognates (Tetraodontiformes), 4. Lophobranches (Syngnathidae), 5. Malacoptérygiens abdominaux, 6. Malacoptérygiens subbrachiens, 7. Malacoptérygiens apodes, 8. Acanthoptérygiens (Acanthopterygians).
II. Mollusques. (Molluscs)
Céphalopodes. (Cephalopods)
Ptéropodes. (Pteropods)
Gastéropodes (Gastropods): 1. Nudibranches (Nudibranchs), 2. Inférobranches, 3. Tectibranches, 4. Pulmonés (Pulmonata), 5. Pectinibranches, 6. Scutibranches, 7. Cyclobranches.
Acéphales (Bivalves etc.): 1. Testacés, 2. Sans coquilles.
Brachiopodes. (Brachiopods, now a separate phylum)
Cirrhopodes. (Barnacles, now in Crustacea)
III. Articulés. (Articulated animals: now Arthropods and Annelids)
Annélides (Annelids): 1. Tubicoles, 2. Dorsibranches, 3. Abranches.
Crustacés (Crustaceans): 1. Décapodes (Decapods), 2. Stomapodes (Stomatopods), 3. Amphipodes (Amphipods), 4. Isopodes (Isopods), 5. Branchiopodes (Branchiopods).
Arachnides (Arachnids): 1. Pulmonaires, 2. Trachéennes.
Insectes (Insects, inc. Myriapods): 1. Myriapodes, 2. Thysanoures (Thysanura), 3. Parasites, 4. Suceurs, 5. Coléoptères (Coleoptera), 6. Orthoptères (Orthoptera), 7. Hémiptères (Hemiptera), 8. Névroptères (Neuroptera), 9. Hyménoptères (Hymenoptera), 10. Lépidoptères (Lepidoptera), 11. Ripiptères (Strepsiptera), 12. Diptères (Diptera).
IV. Zoophytes. (Zoophytes, now Cnidaria] and other phyla)
Échinodermes (Echinoderms): 1. Pédicellés, 2. Sans pieds.
Intestinaux (Intestinal worms): 1. Cavitaires, 2. Parenchymateux.
Acalèphes (Jellyfish and other free-floating polyps): 1. Fixes, 2. Libres.
Polypes (Cnidaria): 1. Nus, 2. À polypiers.
Infusoires (Infusoria, various protistan phyla): 1. Rotifères (Rotifers), 2. Homogènes.
Reception
The book was in the library of HMS Beagle for Charles Darwin's voyage.[21] In The Origin of Species (1859), in a chapter on the difficulties facing the theory, Darwin comments that "The expression of conditions of existence,[b] so often insisted on by the illustrious Cuvier, is fully embraced by the principle of natural selection." In fact Darwin did not argue that God could not have created the first living organism, but Darwin did believe that organisms evolved.
https://en.wikipedia.org/wiki/Domain_(biology)
The fourth domain is different
Characteristics of the three domains of life[edit]
A speculatively rooted tree for RNA genes, showing major branches Bacteria, Archaea, and Eukaryota
The three-domains tree and the Eocyte hypothesis(Two domains tree).[4]
Phylogenetic tree showing the relationship between the eukaryotes and other forms of life.[5] Eukaryotes are colored red, archaea green and bacteria blue.
Each of these three domains of life recognized by biologists today contain rRNA which is unique to them, and this fact in itself forms the basis of the three-domain system. While the presence of a nuclear membrane differentiates the Eukarya domain from the Archaea and Bacteria domains, both of which lack a nuclear membrane, distinct biochemical and RNA markers differentiate the Archaea and Bacteria domains from each other.
Archaea[edit]
Archaea are prokaryotic cells which are typically characterized by membrane lipids that are branched hydrocarbon chains attached to glycerol by ether linkages. The presence of these ether linkages in Archaea adds to their ability to withstand extreme temperatures and highly acidic conditions, but many archea live in mild environments. Halophiles, organisms which thrive in highly salty environments, and hyperthermophiles, organisms which thrive in extremely hot environments, are examples of Archaea. Archaea evolved many cell sizes, but all are relatively small. Their size ranges from 0.1 to 15 μ diameter and up to 200 μ long. They are about the size of bacteria or similar to the size of a mitochondrion in a eukaryotic cell. Members of the genus Thermoplasma are the smallest of the archaea.
Bacteria[edit]
Even though bacteria are prokaryotic cells just like Archaea, their membranes are made of unbranched fatty acid chains attached to glycerol by ester linkages. Cyanobacteria and mycoplasmas are two examples of bacteria. They characteristically do not have ether linkages like Archaea, and they are grouped into a different category—and hence a different domain. There is a great deal of diversity in this domain, and between that and horizontal gene transfer, it is next to impossible to determine how many species of bacteria exist on the planet.
Eukarya[edit]
Organisms in the domain Eukarya are eukaryotic cells, or consist of them, which have membranes that are similar to those of bacteria. Eukaryotes are further grouped into Kingdom Fungi (yeast, mold, etc.), Kingdom Plantae (flowering plants, ferns, etc.) and Kingdom Animalia (insects, vertebrates, etc.) and the now-defunct, paraphyletic Kingdom Protista (algae, protozoans, etc.).
Not all Eukaryotes have a cell wall, and even in those which do, the walls do not contain peptidoglycan, which bacteria do have. While cells are organized into tissues in the kingdom Plantae as well as the kingdom Animalia, cell walls are never found in animal cells.
Exclusion of viruses[edit]
Main article: Virus
None of the three systems currently include non-cellular life. As of 2011 there is talk about Nucleocytoplasmic large DNA viruses possibly being a fourth branch domain of life, a view supported by researchers in 2012.[6]
Stefan Luketa in 2012 proposed a five-domain system, adding Prionobiota (acellular and without nucleic acid) and Virusobiota (acellular but with nucleic acid) to the traditional three domains.[2]
https://en.wikipedia.org/wiki/Tetracarpaea
Named by William Jackson Hooker in 1840, the name Tetracarpaea refers to the four conspicuous and separate carpels.[10] At that time, he wrote:
This beautiful little shrub is altogether new to me: but much as it differs in certain characters, both of the foliage and fructification, from the Order Cunoniaceae, I think it may safely be referred to it. The 4 carpels, which have suggested the Generic name, are perfectly free even in the earliest state of the ovary.
— William Jackson Hooker
The following description is based on information from several sources.[1][2][6][8][9]
Tetracarpaea tasmannica is a glabrous, evergreen, erect and bushy shrub. It is variable in height, usually from 1.5 to 6 dm, but sometimes attaining a height of 1 m and a width of 7 dm.
The leaves are elliptic to oblanceolate, about 25 mm long and 8 mm wide, on a petiole about 2 mm long. The veins are prominent and end near the margin. The margins are serrate or crenate. On both surfaces, the epidermis is covered by a thick cuticle.
The inflorescences are dense, erect, terminal racemes, up to 5 cm long. The flowers appear in autumn. They are bisexual, actinomorphic, and 5 to 10 mm wide. The 4 sepals persist to the maturity of the fruit. The 4 petals are white and spatulate in shape.
The stamens are either 4 or 8 in number. If 4, they are opposite (along the same radii as) the sepals. The anthers are basifixed.
The ovary is superior and consists of 4 carpels that are large compared to the rest of the flower. The carpels are usually separate, but occasionally 2 or 3 of them are fused at the base, or rarely, as far as halfway up. They are erect and stipitate with a suture along the ventral side. A placenta runs along each side of the suture and bears 1 to 3 rows of numerous, tiny ovules. The ovules have been described as having one integument[8] or two.[6]
The ovary hardly enlarges after anthesis. The fruit consists of 4 follicles joined at the base. The seeds are numerous and about ½ mm long.
https://en.wikipedia.org/wiki/Syphilis
Signs and symptoms
Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary,[3] and may also occur congenitally.[12] It was referred to as "the great imitator" by Sir William Osler due to its varied presentations.[3][13]
Primary
Primary chancre of syphilis at the site of infection on the penis
Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person.[14] Approximately 3 to 90 days after the initial exposure (average 21 days) a skin lesion, called a chancre, appears at the point of contact. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders 0.3–3.0 cm in size.[3] The lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer.[15] Occasionally, multiple lesions may be present (~40%),[3] with multiple lesions more common when coinfected with HIV. Lesions may be painful or tender (30%), and they may occur in places other than the genitals (2–7%). The most common location in women is the cervix (44%), the penis in heterosexual men (99%), and anally and rectally relatively commonly in men who have sex with men (34%).[15] Lymph node enlargement frequently (80%) occurs around the area of infection,[3] occurring seven to 10 days after chancre formation.[15] The lesion may persist for three to six weeks without treatment.[3]
Secondary
Typical presentation of secondary syphilis with a rash on the palms of the hands
Reddish papules and nodules over much of the body due to secondary syphilis
Secondary syphilis occurs approximately four to ten weeks after the primary infection.[3] While secondary disease is known for the many different ways it can manifest, symptoms most commonly involve the skin, mucous membranes, and lymph nodes.[16] There may be a symmetrical, reddish-pink, non-itchy rash on the trunk and extremities, including the palms and soles.[3][17] The rash may become maculopapular or pustular. It may form flat, broad, whitish, wart-like lesions known as condyloma latum on mucous membranes. All of these lesions harbor bacteria and are infectious. Other symptoms may include fever, sore throat, malaise, weight loss, hair loss, and headache.[3] Rare manifestations include liver inflammation, kidney disease, joint inflammation, periostitis, inflammation of the optic nerve, uveitis, and interstitial keratitis.[3][18] The acute symptoms usually resolve after three to six weeks;[18] about 25% of people may present with a recurrence of secondary symptoms. Many people who present with secondary syphilis (40–85% of women, 20–65% of men) do not report previously having had the classic chancre of primary syphilis.[16]
Latent
Latent syphilis is defined as having serologic proof of infection without symptoms of disease.[14] It is further described as either early (less than 1 year after secondary syphilis) or late (more than 1 year after secondary syphilis) in the United States.[18] The United Kingdom uses a cut-off of two years for early and late latent syphilis.[15] Early latent syphilis may have a relapse of symptoms. Late latent syphilis is asymptomatic, and not as contagious as early latent syphilis.[18]
Tertiary
Person with tertiary (gummatous) syphilis. Bust in Musée de l'Homme, Paris.
Tertiary syphilis may occur approximately 3 to 15 years after the initial infection, and may be divided into three different forms: gummatous syphilis (15%), late neurosyphilis (6.5%), and cardiovascular syphilis (10%).[3][18] Without treatment, a third of infected people develop tertiary disease.[18] People with tertiary syphilis are not infectious.[3]
Gummatous syphilis or late benign syphilis usually occurs 1 to 46 years after the initial infection, with an average of 15 years. This stage is characterized by the formation of chronic gummas, which are soft, tumor-like balls of inflammation which may vary considerably in size. They typically affect the skin, bone, and liver, but can occur anywhere.[3]
Neurosyphilis refers to an infection involving the central nervous system. It may occur early, being either asymptomatic or in the form of syphilitic meningitis, or late as meningovascular syphilis, general paresis, or tabes dorsalis, which is associated with poor balance and lightning pains in the lower extremities. Late neurosyphilis typically occurs 4 to 25 years after the initial infection. Meningovascular syphilis typically presents with apathy and seizure, and general paresis with dementia and tabes dorsalis.[3] Also, there may be Argyll Robertson pupils, which are bilateral small pupils that constrict when the person focuses on near objects but do not constrict when exposed to bright light.
Cardiovascular syphilis usually occurs 10–30 years after the initial infection. The most common complication is syphilitic aortitis, which may result in aneurysm formation.[3]
The fourth is always different/transcendent
In 1953, Cambridge researchers Watson and Crick published a paper describing the interweaving ‘double helix’ DNA structure – the chemical code for all life.
Now, in the year of that scientific landmark’s 60th Anniversary, Cambridge researchers have published a paper proving that four-stranded ‘quadruple helix’ DNA structures – known as G-quadruplexes – also exist within the human genome. They form in regions of DNA that are rich in the building block guanine, usually abbreviated to ‘G’.
The findings mark the culmination of over 10 years investigation by scientists to show these complex structures in vivo – in living human cells – working from the hypothetical, through computational modelling to synthetic lab experiments and finally the identification in human cancer cells using fluorescent biomarkers.
The research, published today in Nature Chemistry and funded by Cancer Research UK, goes on to show clear links between concentrations of four-stranded quadruplexes and the process of DNA replication, which is pivotal to cell division and production.
By targeting quadruplexes with synthetic molecules that trap and contain these DNA structures – preventing cells from replicating their DNA and consequently blocking cell division – scientists believe it may be possible to halt the runaway cell proliferation at the root of cancer.
“We are seeing links between trapping the quadruplexes with molecules and the ability to stop cells dividing, which is hugely exciting,” said Professor Shankar Balasubramanian from the University of Cambridge’s Department of Chemistry and Cambridge Research Institute, whose group produced the research.
“The research indicates that quadruplexes are more likely to occur in genes of cells that are rapidly dividing, such as cancer cells. For us, it strongly supports a new paradigm to be investigated – using these four-stranded structures as targets for personalised treatments in the future.”
Physical studies over the last couple of decades had shown that quadruplex DNA can form in vitro – in the ‘test tube’, but the structure was considered to be a curiosity rather than a feature found in nature. The researchers now know for the first time that they actually form in the DNA of human cells.
“This research further highlights the potential for exploiting these unusual DNA structures to beat cancer – the next part of this pipeline is to figure out how to target them in tumour cells,” said Dr Julie Sharp, senior science information manager at Cancer Research UK.
“It’s been sixty years since its structure was solved but work like this shows us that the story of DNA continues to twist and turn.”
16 is the squares of the quadrant model
https://en.wikipedia.org/wiki/The_Canon_of_Medicine
The Canon then describes when temperaments are unequal, in other words, illness. Avicenna separates these into two categories, which are fairly self explainable within the context of what he had already defined as the four temperaments.
A. Simple "intemperaments"[8]:63
Hot temperament (hotter than normal)
Cold temperament (colder than normal)
Dry temperament (drier than usual)
Moist temperament (more moist than usual)
B. Compound "intemperaments"
The compound intemperaments are where two things are wrong with the temperament, i.e. hotter and moister; hotter and drier; colder and moister; colder and drier. There are only four because something cannot be simultaneously hotter and colder or drier and moister. The four simple temperaments and four compound intemperaments can each be divided into "Those apart from any material substance" and "Those in which some material substance is concerned", for a total of sixteen intemperaments. Examples of the sixteen intemperaments are provided in the "third and fourth volumes."[8]:64
https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life
The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970.[1] It is a hugely important game in the study of biology. It is played in quadrants.
The "game" is a zero-player game, meaning that its evolution is determined by its initial state, requiring no further input. One interacts with the Game of Life by creating an initial configuration and observing how it evolves or, for advanced players, by creating patterns with particular properties.
The universe of the Game of Life is an infinite two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, alive or dead. Every cell interacts with its eight neighbours, which are the cells that are horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur:
Square 1: Any live cell with fewer than two live neighbours dies, as if caused by under-population.
Square 2: Any live cell with two or three live neighbours lives on to the next generation.
Square 3: Any live cell with more than three live neighbours dies, as if by over-population.
Square 4: Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction
Conway chose his rules carefully, after considerable experimentation, to meet these criteria:
Square 1: There should be no explosive growth.
Square 2: There should exist small initial patterns with chaotic, unpredictable outcomes.
Square 3: There should be potential for von Neumann universal constructors.
Square 4: The rules should be as simple as possible, whilst adhering to the above constraints.[9]
Patterns relating to fractals and fractal systems may also be observed in certain Life-like variations. For example, the automaton B1/S12 generates four very close approximations to the Sierpiński triangle when applied to a single live cell. The Sierpiński triangle can also be observed in Conway's Game of Life by examining the long-term growth of a long single-cell-thick line of live cells,[38] as well as in Highlife, Seeds (B2/S), and Wolfram's Rule 90.[39]
Immigration is a variation that is very similar to Conway's Game of Life, except that there are two ON states (often expressed as two different colours). Whenever a new cell is born, it takes on the ON state that is the majority in the three cells that gave it birth. This feature can be used to examine interactions between spaceships and other "objects" within the game.[40] Another similar variation, called QuadLife, involves four different ON states. When a new cell is born from three different ON neighbours, it takes on the fourth value, and otherwise, like Immigration, it takes the majority value.[41] Except for the variation among ON cells, both of these variations act identically to Life
https://en.wikipedia.org/wiki/Big_cat
I discussed how there are four "great apes". There are also four "big cats"
I put this in one of my books
The informal term "big cat" is typically used to refer to any of the four largest (living) members of the entire Panthera genus. Among the five total species within the Panthera genus, these four are the only animals that are able to roar.[1] In descending order of their maximum potential size, these four species are: tigers, lions, jaguars, and leopards.[1]
https://en.wikipedia.org/wiki/Quadrantanopia
Quadrantanopia, quadrantanopsia, or quadrant anopia refers to an anopia affecting a quarter of the field of vision.
It can be associated with a lesion of an optic radiation.[1] While quadrantanopia can be caused by lesions in the temporal and parietal lobes, it is most commonly associated with lesions in the occipital lobe.[2] If Meyer's loop (temporal pathway) is lesioned, the vision loss is superior (colloquially referred to as "pie in the sky"); if Baum's loop (parietal pathway) is lesioned, the vision loss is inferior.[3]
https://en.wikipedia.org/wiki/Cleavage_(embryo)
Holoblastic[edit]
In the absence of a large concentration of yolk, four major cleavage types can be observed in isolecithal cells (cells with a small even distribution of yolk) or in mesolecithal cells (moderate amount of yolk in a gradient) – bilateral holoblastic, radial holoblastic, rotational holoblastic, and spiral holoblastic, cleavage.[2] These holoblastic cleavage planes pass all the way through isolecithal zygotes during the process of cytokinesis. Coeloblastula is the next stage of development for eggs that undergo these radial cleavaging. In holoblastic eggs, the first cleavage always occurs along the vegetal-animal axis of the egg, the second cleavage is perpendicular to the first. From here, the spatial arrangement of blastomeres can follow various patterns, due to different planes of cleavage, in various organisms.
Bilateral
The first cleavage results in bisection of the zygote into left and right halves. The following cleavage planes are centered on this axis and result in the two halves being mirror images of one another. In bilateral holoblastic cleavage, the divisions of the blastomeres are complete and separate; compared with bilateral meroblastic cleavage, in which the blastomeres stay partially connected.
Radial
Radial cleavage is characteristic of the deuterostomes, which include some vertebrates and echinoderms, in which the spindle axes are parallel or at right angles to the polar axis of the oocyte.
Rotational
Mammals display rotational cleavage, and an isolecithal distribution of yolk (sparsely and evenly distributed). Because the cells have only a small amount of yolk, they require immediate implantation onto the uterine wall in order to receive nutrients.
Rotational cleavage involves a normal first division along the meridional axis, giving rise to two daughter cells. The way in which this cleavage differs is that one of the daughter cells divides meridionally, whilst the other divides equatorially.
Spiral
Spiral cleavage is conserved between many members of the lophotrochozoan taxa, referred to as Spiralia.[3] Most spiralians undergo equal spiral cleavage, although some undergo unequal cleavage (see below).[4] This group includes annelids, molluscs, and sipuncula. Spiral cleavage can vary between species, but generally the first two cell divisions result in four macromeres, also called blastomeres, (A, B, C, D) each representing one quadrant of the embryo. These first two cleavages are oriented in planes that occur at right angles parallel to the animal-vegetal axis of the zygote.[3] At the 4-cell stage, the A and C macromeres meet at the animal pole, creating the animal cross-furrow, while the B and D macromeres meet at the vegetal pole, creating the vegetal cross-furrow.[5] With each successive cleavage cycle, the macromeres give rise to quartets of smaller micromeres at the animal pole.[6][7] The divisions that produce these quartets occur at an oblique angle, an angle that is not a multiple of 90°, to the animal-vegetal axis.[7] Each quartet of micromeres is rotated relative to their parent macromere, and the chirality of this rotation differs between odd and even numbered quartets, meaning that there is alternating symmetry between the odd and even quartets.[3] In other words, the orientation of divisions that produces each quartet alternates between being clockwise and counterclockwise with respect to the animal pole.[7] The alternating cleavage pattern that occurs as the quartets are generated produces quartets of micromeres that reside in the cleavage furrows of the four macromeres.[5] When viewed from the animal pole, this arrangement of cells displays a spiral pattern.
D quadrant specification through equal and unequal cleavage mechanisms. At the 4-cell stage of equal cleavage, the D macromere has not been specified yet. It will be specified after the formation of the third quartet of micromeres. Unequal cleavage occurs in two ways: asymmetric positioning of the mitotic spindle, or through the formation of a polar lobe (PL).
Specification of the D macromere and is an important aspect of spiralian development. Although the primary axis, animal-vegetal, is determined during oogenesis, the secondary axis, dorsal-ventral, is determined by the specification of the D quadrant.[7] The D macromere facilitates cell divisions that differ from those produced by the other three macromeres. Cells of the D quadrant give rise to dorsal and posterior structures of the spiralian.[7] Two known mechanisms exist to specify the D quadrant. These mechanisms include equal cleavage and unequal cleavage.
In equal cleavage, the first two cell divisions produce four macromeres that are indistinguishable from one another. Each macromere has the potential of becoming the D macromere.[6] After the formation of the third quartet, one of the macromeres initiates maximum contact with the overlying micromeres in the animal pole of the embryo.[6][7] This contact is required to distinguish one macromere as the official D quadrant blastomere. In equally cleaving spiral embryos, the D quadrant is not specified until after the formation of the third quartet, when contact with the micromeres dictates one cell to become the future D blastomere. Once specified, the D blastomere signals to surrounding micromeres to lay out their cell fates.[7]
In unequal cleavage, the first two cell divisions are unequal producing four cells in which one cell is bigger than the other three. This larger cell is specified as the D macromere.[6][7] Unlike equally cleaving spiralians, the D macromere is specified at the four-cell stage during unequal cleavage. Unequal cleavage can occur in two ways. One method involves asymmetric positioning of the cleavage spindle.[7] This occurs when the aster at one pole attaches to the cell membrane, causing it to be much smaller than the aster at the other pole.[6] This results in an unequal cytokinesis, in which both macromeres inherit part of the animal region of the egg, but only the bigger macromere inherits the vegetal region.[6] The second mechanism of unequal cleavage involves the production of an enucleate, membrane bound, cytoplasmic protrusion, called a polar lobe.[6] This polar lobe forms at the vegetal pole during cleavage, and then gets shunted to the D blastomere.[5][6] The polar lobe contains vegetal cytoplasm, which becomes inherited by the future D macromere.[7]
https://en.wikipedia.org/wiki/Robert_Koch
Robert Heinrich Herman Koch (/ˈkɔːx/;[3] German: [ˈkɔχ]; 11 December 1843 – 27 May 1910) was a celebrated German physician and pioneering microbiologist. As the founder of modern bacteriology, he is known for his role in identifying the specific causative agents of tuberculosis, cholera, and anthrax and for giving experimental support for the concept of infectious disease.[4] In addition to his trail-blazing studies on these diseases, Koch created and improved laboratory technologies and techniques in the field of microbiology, and made key discoveries in public health.[5] His research led to the creation of Koch’s postulates, a series of four generalized principles linking specific microorganisms to specific diseases that remain today the "gold standard" in medical microbiology.[5] As a result of his groundbreaking research on tuberculosis, Koch received the Nobel Prize in Physiology or Medicine in 1905.
Koch's postulates revolutionized science and biology.
Koch's four postulates are the following:
Square 1: The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
Square 2: The microorganism must be isolated from a diseased organism and grown in pure culture.
Square 3: The cultured microorganism should cause disease when introduced into a healthy organism.
Square 4: The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
During his time as the government advisor with the Imperial Department of Health in Berlin in the 1880s, Robert Koch became interested in tuberculosis research.[4] At the time, it was widely believed that tuberculosis was an inherited disease.[4] However, Koch was convinced that the disease was caused by a bacterium and was infectious, and tested his four postulates using guinea pigs.[4] Through these experiments, he found that his experiments with tuberculosis satisfied all four of his postulates.[4] In 1882, he published his findings on tuberculosis, in which he reported the causative agent of the disease to be the slow-growing Mycobacterium tuberculosis.[11] His work with this disease won Koch the Nobel Prize in Physiology and Medicine in 1905.[4] Additionally, Koch's research on tuberculosis, along with his studies on tropical diseases, won him the Prussian Order Pour le Merite in 1906 and the Robert Koch medal, established to honour the greatest living physicians, in 1908.[4]
https://en.wikipedia.org/wiki/Tic
Tics are classified as either motor or phonic, and simple or complex.
Simple motor tics are typically sudden, brief, meaningless movements that usually involve only one group of muscles, such as eye blinking, head jerking, or shoulder shrugging.[6] Motor tics can be of an endless variety and may include such movements as hand clapping, neck stretching, mouth movements, head, arm or leg jerks, and facial grimacing.
A simple phonic tic can be almost any sound or noise, with common vocal tics being throat clearing, sniffing, or grunting.[6]
Complex motor tics are typically more purposeful-appearing and of a longer nature. They may involve a cluster of movements and appear coordinated.[6] Examples of complex motor tics are pulling at clothes, touching people, touching objects, echopraxia (repeating or imitating another person's actions) and copropraxia (involuntarily performing obscene or forbidden gestures).
Complex phonic tics include echolalia (repeating words just spoken by someone else), palilalia (repeating one's own previously spoken words), lexilalia (repeating words after reading them), and coprolalia (the spontaneous utterance of socially objectionable or taboo words or phrases). Coprolalia is a highly publicized symptom of Tourette syndrome; however, only about 10% of TS patients exhibit coprolalia.[6]
https://sites.google.com/site/ekgsmadesimple/e-qrs-axis/calcualting-qrs-quadrants
Calculating the QRS Quadrant for the heart.
One method used to calculate QRS quadrant is to look at leads I and aVF. Remember from earlier, the electrical impulse originates in the SA node of the right atrium and travels through the AV node down through the ventricles. The impulse follows the pathway of Lead II, right arm to the left leg.
When the QRS in Lead I is positive, it means the electricity is moving through the persons heart from right to left (normal pathway).
If the QRS is negative in lead I, then the electricity is moving left to right (abnormal).
This means that if the electricity is traveling to the left, the QRS axis quadrant will either be NORMAL AXIS or LAD.
If the electricity is traveling to the right, the QRS axis quadrant will either be RAD or UNKNOWN.
Now we will look at aVF. If the QRS is positive, it means the electricity is moving through the heart from top to bottom (normal pathway).
If the QRS in aVF is negative, the electricity is moving from the bottom to the top (abnormal).
This means that if the electricity is moving from the top to the bottom, the QRS axis quadrant is NORMAL AXIS of RAD.
However, if the electricity is traveling upward, the QRS axis quadrant is Unknown or LAD.
The diagram below illustrates these rules in their corresponding quadrants. For instance, If the QRS in Lead I is (+) and aVF is (-), that places the axis in the LAD quadrant.
image from http://general.utpb.edu/…/eldridge_j/KINE3351/quadrant_1.gif
Causes of QRS Deviation
Causes of Left Axis Deviation (LAD), where the QRS axis is in the LAD quadrant:
Left Ventricular Hypertrophy (LVH): requires more electricity due to the increase size of the ventricle causing the electricle path to swing further to the left.
Left Bundle Branch Block (LBBB): Since the left bundle is blocked, the electrical path travels down the right bundle, then the electrical stimulation has to travel from cell to cell to stimulate the left ventricle to depolarize causing the QRS axis to deviate to the left.
Inferior Wall MI: In an Inferior MI, the elctrical path has to deviate to the left to go up and around the infarcted tissue, swing the pathway to the left side.
Causes of Right Axis Deviation (RAD), where the QRS axis is in the RAD quadrant:
Dextrocardia: born with heart on the right side
Anterior MI
Right Ventricular Hypertrophy (RVH)
Right Bundle Branch Block (RBBB)
Ventricular Tachycardia
COPD/Pulmonary Hypertension
https://en.wikipedia.org/wiki/Nuclear_receptor
nuclear receptors may be subdivided into the following four mechanistic classes:[4][5]
Type I[edit]
Ligand binding to type I nuclear receptors in the cytosol results in the dissociation of heat shock proteins, homo-dimerization, translocation (i.e., active transport) from the cytoplasm into the cell nucleus, and binding to specific sequences of DNA known as hormone response elements (HREs). Type I nuclear receptors bind to HREs consisting of two half-sites separated by a variable length of DNA, and the second half-site has a sequence inverted from the first (inverted repeat). Type I nuclear receptors include members of subfamily 3, such as the androgen receptor, estrogen receptors, glucocorticoid receptor, and progesterone receptor.[24]
It has been noted that some of the NR subfamily 2 nuclear receptors may bind to direct repeat instead of inverted repeat HREs. In addition, some nuclear receptors that bind either as monomers or dimers, with only a single DNA binding domain of the receptor attaching to a single half site HRE. These nuclear receptors are considered orphan receptors, as their endogenous ligands are still unknown.
The nuclear receptor/DNA complex then recruits other proteins that transcribe DNA downstream from the HRE into messenger RNA and eventually protein, which causes a change in cell function.
Type II[edit]
Type II receptors, in contrast to type I, are retained in the nucleus regardless of the ligand binding status and in addition bind as hetero-dimers (usually with RXR) to DNA. In the absence of ligand, type II nuclear receptors are often complexed with corepressor proteins. Ligand binding to the nuclear receptor causes dissociation of corepressor and recruitment of coactivator proteins. Additional proteins including RNA polymerase are then recruited to the NR/DNA complex that transcribe DNA into messenger RNA.
Type II nuclear receptors include principally subfamily 1, for example the retinoic acid receptor, retinoid X receptor and thyroid hormone receptor.[25]
Type III[edit]
Type III nuclear receptors (principally NR subfamily 2) are similar to type I receptors in that both classes bind to DNA as homodimers. However, type III nuclear receptors, in contrast to type I, bind to direct repeat instead of inverted repeat HREs.
Type IV[edit]
Type IV nuclear receptors bind either as monomers or dimers, but only a single DNA binding domain of the receptor binds to a single half site HRE. Examples of type IV receptors are found in most of the NR subfamilies.
Like
Scientists have analysed the largest collection of human fossils on the planet, dating back 430,000 years, and have found that the human body went through four main stages of evolution before settling on the shape and size we see around us today.
The fossils were from the Sima de los Huesos site in northern Spain, and the humans located there are often referred to as Atapuerca humans. The researchers found that these ancient humans shared many anatomical features with the late Neanderthals, but not modern humans, and therefore represent the third stage of human body evolution.
"This is really interesting since it suggests that the evolutionary process in our genus is largely characterised by stasis (i.e. little to no evolutionary change) in body form for most of our evolutionary history," lead author Rolf Quam, an anthropologist from Binghamton University in the US, said in a press release.
The team's analysis of these fossils revealed that the Atapuerca individuals, who lived around 430,000 years ago, were relatively tall, with wide, muscular bodies and less brain mass relative to body mass than the Neanderthals.
Using this information, the researchers were able to hypothesise that there were four main stages that got the Homo genus to where it is today. The first stage occurred hundreds of thousands of years ago, when our hominid ancestors began to migrate out of Africa. The second stage was the evolution of Neanderthals, while the third stage brought about the Atapuerca humans, who finally evolved into our modern body shape.
Each of these stages can be characterised by the amount of walking on two legs versus living in trees the hominids participated in. By the third stage, there was no evidence of tree-dwelling in the human skeleton.
But despite the differences, the researchers explain that the Atapuerca humans likely shared the same wide and robust body forms as our ancestors Homo erectus and the Neanderthals, and that the body form was probably around in the Homo genus for more than a million years.
"It was not until the appearance of our own species, Homo sapiens, when a new taller, lighter and narrower body form emerged," the press release explains. "Thus, the authors suggest that the Atapuerca humans offer the best look at the general human body shape and size during the last million years before the advent of modern humans."
https://en.wikipedia.org/wiki/Nasal_conchahttps://en.wikipedia.org/wiki/Nasal_concha
In anatomy, a nasal concha (/ˈkɒnkə/), plural conchae (/ˈkɒnki/), also called a turbinate or turbinal, is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various animals. The conchae are shaped like an elongated seashell, which gave them their name (Latin concha from Greek κόγχη). A turbinate bone is any of the scrolled spongy bones of the nasal passages in vertebrates.[1]
In humans, the turbinates divide the nasal airway into 4 groove-like air passages, and are responsible for forcing inhaled air to flow in a steady, regular pattern around the largest possible surface area of nasal mucosa, which, as a ciliated mucous membrane with shallow blood supply, cleans and warms the inhaled air in preparation for the lungs.
https://en.wikipedia.org/wiki/Anatomy_of_the_human_nose
The movements of the nose are affected by
the elevator muscle group — which includes the procerus muscle and the levator labii superioris alaeque nasi muscle.
the depressor muscle group — which includes the alar nasalis muscle and the depressor septi nasi muscle.
the compressor muscle group — which includes the transverse nasalis muscle.
the dilator muscle group — which includes the dilator naris muscle that expands the nostrils; it is in two parts: (i) the dilator nasi anterior muscle, and (ii) the dilator nasi posterior muscle.
https://en.wikipedia.org/wiki/File:Dental_quadrants.png
https://en.wikipedia.org/wiki/Glossary_of_dentistry
The dentition is divided into four quarters. The two dental arches form an oval, which is divided into quadrants:
Upper right quadrant: upper right first incisor to upper right wisdom tooth
Upper left quadrant: upper left first incisor to upper left wisdom tooth
Lower right quadrant: lower right first incisor to lower right wisdom tooth
Lower left quadrant: lower left first incisor to lower left wisdom tooth
https://en.wikipedia.org/wiki/Quadrant_(abdomen)
The human abdomen is divided into regions by anatomists and physicians for purposes of study, diagnosis, and therapy.[1] [2] In the four-region scheme, four quadrants allow localisation of pain and tenderness, scars, lumps, and other items of interest, narrowing in on which organs and tissues may be involved. The quadrants are referred to as the left lower quadrant, left upper quadrant, right upper quadrant and right lower quadrant, as follows.
The left lower quadrant (LLQ) of the human abdomen is the area left of the midline and below the umbilicus. The LLQ includes the left iliac fossa and half of the left flank region.
The term is not used in comparative anatomy, since most other animals do not stand erect. The equivalent term for animals is left posterior quadrant.
The left upper quadrant (LUQ) extends from the median plane to the left of the patient, and from the umbilical plane to the left ribcage.
The equivalent term for animals is 'left anterior quadrant'.
The right upper quadrant (RUQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right ribcage.
The equivalent term for animals is 'right anterior quadrant'.
The right lower quadrant (RLQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right inguinal ligament.
The equivalent term for animals is 'right posterior quadrant'.
In the LLQ if abdominal pain or signs of peritonitis are localised, colitis, diverticulitis, ureteral colic or pain due to ovarian cysts or pelvic inflammatory disease, may be suspected. Examples of tumours in the left lower quadrant include colon cancer or ovarian tumour.
The LUQ may be painful or tender in appendicitis, and in the case of intestinal malrotation.
The RUQ may be painful or tender in hepatitis, cholecystitis, and peptic ulcer.
The RLQ may be painful and/or tender in such conditions as appendicitis.
Like
https://en.wikipedia.org/wiki/Four_Fish
Four Fish: The Future of the Last Wild Food is a 2010 nonfiction book by author Paul Greenberg. This work explores the state of commercial fishing and aquaculture. Greenberg frames his observations by commenting on the status of four specific fish: cod, salmon, bass, and tuna. Choosing four fish was a decision influenced by author Michael Pollan's selection of four plants in his book, The Botany of Desire. [1]
The New York Times gave the book a positive review.[2] David Helvarg gave the book a positive review on sfgate.com.[3] The book was reviewed by The Los Angeles Times.
QMR
Flowers have four basic parts.the floral organs of eudicotyledonous angiosperms (flowers) are arranged in 4 different verticils, containing the Square 1: sepals,
Square 2: petals,
Square 3: stamen
Square 4: carpels. The ABC model states that the identity of these organs is determined by the homeotic genes
Square 1: A,
Square 2: A+B,
Square 3B+C
Square 4: C
Flowers should fit the quadrant model pattern because in the plant world they are the paragon. Like humans who are the paragon of animals, flowers project the quadrant model image
FOUR CELL GROUPS OF VENTRAL RESPIRATORY GROUP
https://en.wikipedia.org/wiki/Ventral_respiratory_group
The (VRG) is a column of neurons located in the ventrolateral region of the medulla, extending from the caudal facial nucleus to -400μm obex. The four cell groups of the VRG are the rostral nucleus retrofacialis, caudal nucleus retroambiguus, nucleus para-ambiguus, and the pre-Bötzinger complex.
FOUR FAMILIES MOLECULES RESPONSIBLE CELL JUNCTIONS
https://en.wikipedia.org/wiki/Cell_junction
The molecules responsible for creating cell junctions include various cell adhesion molecules. There are four main types: selectins, cadherins, integrins, and the immunoglobulin superfamily.[12]
Selectins are cell adhesion molecules that play an important role in the initiation of inflammatory processes.[13] The functional capacity of selectin is limited to leukocyte collaborations with vascular endothelium. There are three types of selectins found in humans; L-selectin, P-selectin and E-selectin. L-selectin deals with lymphocytes, monocytes and neutrophils, P-selectin deals with platelets and endothelium and E-selectin deals only with endothelium. They have extracellular regions made up of an amino-terminal lectin domain, attached to a carbohydrate ligand, growth factor-like domain (EGF) and short repeat units (numbered circles) that match the complimentary binding protein domains.[14]
Cadherins are calcium-dependent adhesion molecules. Cadherins are extremely important in the process of morphogenesis – fetal development. Together with an alpha-beta catenin complex, the cadherin can bind to the microfilaments of the cytoskeleton of the cell. This allows for homophilic cell–cell adhesion.[15] The β-catenin–α-catenin linked complex at the adherens junctions allows for the formation of a dynamic link to the actin cytoskeleton.[16]
Integrins act as adhesion receptors, transporting signals across the plasma membrane in multiple directions. These molecules are an invaluable part of cellular communication, as a single ligand can be used for many integrins. Unfortunately these molecules still have a long way to go in the ways of research.[17]
Immunoglobulin superfamily are a group of calcium independent proteins capable of homophilic and heterophilic adhesion. Homophilic adhesion involves the immunoglobulin-like domains on the cell surface binding to the immunoglobulin-like domains on an opposing cell’s surface while heterophilic adhesion refers to the binding of the immunoglobulin-like domains to integrins and carbohydrates instead.[18]
http://www.healthline.com/human-body-maps/descending-colon
The colon consists of four parts: descending colon, ascending colon, transverse colon, and sigmoid colon.
A FOUR BY FOUR QUADRANT MODEL
http://patrickwhitefield.co.uk/crop-rotation-the-key-to-organic-gardening/
Crop Rotation – the Key to Organic Gardening?
Written by patrickw on January 25, 2014. Posted in Uncategorized
Crop rotation is generally held to be the absolute keystone of organic growing. But in one of my recent videos I said that I don’t really follow a strict rotation in my home garden. The truth is that I do in theory but the practice is never quite the same thing.
Rotation of crops simply means that you don’t grow the same thing in the same bed one year after another. You grow it in another bed and put another crop in that one. Gardening books show neat diagrams of how you divide your plot into four and rotate the crops around over four years, like this.
http://www.answering-islam.org/Quran/Science/embryo.html
It also begs the question as to why, if the Qur'an really is giving us a highly precise scientific account of human development, it only mentions four stages, nutfah, alaqa, mudghah, plus the clothing of bones with flesh.
Merk Diezle shared a link.
Aug 29, 2016 5:57pm
Ramachandran plot - Wikipedia, the free encyclopedia
en.m.wikipedia.org
https://en.m.wikipedia.org/wiki/Ramachandran_plot#
In my qmr books i discussed the ramachandran plot is a quadrant with the fourth square being different as well as many other things in biology you would be amazed ((i went to classes all day everyday in biology and chemistry it was all quadrant model i wrote it in notebooks but i havent gone through the notebooks yet)
https://en.wikipedia.org/wiki/Quadrumana
Quadrumana and Bimana form an obsolete division of the primates: the Quadrumana are primates with four hands (two attached to the arms and two attached to the legs), and the Bimana are those with two hands and two feet. The attempted division of "Quadrumana" from "Bimana" forms a stage in the long campaign to find a secure way of distinguishing Homo sapiens from the rest of the great apes, a distinction that was culturally essential.[according to whom?]
Quadrumana is Latin for "four-handed ones", which is a term used for apes since they do not have feet attached to their legs as humans do, but instead have hands, as both pairs of hands look almost alike (with the exception of the orangutan, whose hands look exactly the same) and operate exactly like hands.
Bimana is Latin for "two-handed ones", which is a term used for humans, as humans have only two hands, but have two feet which apes do not.
The division was proposed by Johann Friedrich Blumenbach in the first edition of his Manual of Natural History (1779) and taken up by other naturalists, most notably Georges Cuvier.[1] Some elevated the distinction to the level of an order.
However, the many affinities between humans and other primates – and especially the great apes – made it clear that the distinction made no scientific sense. In 1863, however, Thomas Henry Huxley in his Evidence as to Man's Place in Nature demonstrated that the higher apes might fairly be included in Bimana.[2] Charles Darwin wrote, in The Descent of Man (1871):
“ The greater number of naturalists who have taken into consideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, etc. Recently many of our best naturalists have recurred to the view first propounded by Linnaeus, so remarkable for his sagacity, and have placed man in the same Order with the Quadrumana, under the title of the Primates. The justice of this conclusion will be admitted: for in the first place, we must bear in mind the comparative insignificance for classification of the great development of the brain in man, and that the strongly marked differences between the skulls of man and the Quadrumana (lately insisted upon by Bischoff, Aeby, and others) apparently follow from their differently developed brains. In the second place, we must remember that nearly all the other and more important differences between man and the Quadrumana are manifestly adaptive in their nature, and relate chiefly to the erect position of man; such as the structure of his hand, foot, and pelvis, the curvature of his spine, and the position of his head.
Oceanic Zones
http://www.the-science-site.com/oceanic-zones.html
There are four major oceanic zones where plants and animals live in the ocean. The four major zones are intertidal zone, neritic zone, open ocean zone and benthic zone. These zones contain the largest ecosystem on Earth.
Abundant life is found on the summit of a seamount near Guam, NOAA
Major zones in the oceans
Intertidal zone
The intertidal zone is the area of the seafloor between high tide and low tide. It bridges the gap between land and water. Tide pools, estuaries, mangrove swamps and rocky coastal areas are all part of the intertidal zone.
Neritic zone
The water above the continental shelf is the neritic zone. Underwater forest of kelp and grassy meadows of sea grass are home to tiny fish, green turtles, sea cows, seahorses and tiny shrimp. Coral reefs have thousands of animals and plants that live in the waters of the neritic zone.
Open ocean zone
The open ocean zone lies beyond the continental slope and contains 65% of the water in the oceans. This zone is divided further into three subzones. The sunlit zone is where photosynthesis takes place. Plankton and jellyfish are drifters that inhabit this zone. Most animals living in the open ocean live in the sunlit zone.
Twilight zone
Below the sunlit zone is the twilight zone where some light penetrates the ocean to a depth of 3000 feet. Viper fish, firefly squid, and the chambered nautilus live in this zone. The midnight zone extends from a depth of 3000 feet to the seafloor. Animals found in this zone include the giant squid, deep sea hatchetfish and bioluminescent jellyfish.
Benthic zone
The benthic zone includes the entire seafloor. About 200,000 species of plants and animals live here. They live on the continental shelf and continental slope. Hydrothermal vents discovered in 1977 are also teeming with life. These plants and animals doe not need sunlight to exist.
I'm a paragraph. Click here to add your own text and edit me. It's easy.
http://www.singerinstruments.com/yeast-tetrad-dissection/
YEAST TETRAD DISSECTION
Tetrad dissection is a vital tool for yeast geneticists. It is a method by which sporulating yeast cells are teased apart, and the individual cells isolated. Specially designed micromanipulation tools are used to carefully separate the cells of interest, which are then transferred to a new growth medium for further study.
http://study.com/academy/lesson/tetrad-in-meiosis-definition-lesson-quiz.html
What Is a Tetrad?
Imagine two pairs of identical twins standing next to each other to make a group of four. Now, imagine that the people are strands of DNA during meiosis. Bingo, a tetrad.
Okay, it is not a perfect example, but it is a good start.
A tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.
If that is confusing, don't worry. The nitty gritty details are coming right up.
Basic Meiosis Reminder
Humans have 23 different chromosomes (numbered 1-23), but they have two versions of each one. This means that all cells in the human body have 46 chromosomes. Well, except for the sex cells.
If the sperm and egg each had 46 chromosomes, then their offspring would end up with 92 chromosomes. Instead, humans make their sperm and egg cells with only 23 chromosomes each. Then, when they join to make a baby it will have 46 chromosomes, the magic number.
The process of making cells with only half the DNA is called meiosis.
When an egg is fertilized by a sperm, it receives one version of each chromosome from the mother and one from the father. So, two versions of chromosome #1, two versions of chromosome #2, all the way up until two versions of chromosome #23. The two versions of each chromosome are called homologous chromosomes.
Think of your chromosomes like a deck of cards from 1-23. Your father gave you 1-23 of clubs and your mother gave you 1-23 of diamonds. The five of clubs and the five of diamonds are homologous chromosomes. Similar, because they are both number 5…but slightly different.
Forming the Tetrad
Before meiosis can begin, a regular cell replicates its 46 chromosomes. The original version and the new copy remain attached together like conjoined twins and are called sister chromatids. So, just before meiosis, a cell has 46 chromosomes (23 pairs of homologous chromosomes), and each one consists of two sister chromatids. If we think back to our cards, now imagine that you copied each card and stapled the copy to the original. In other words, your five of clubs is stapled to an identical five of clubs.
Meiosis. The long and short chromosomes are different chromosomes. The red and grey are different versions of each. Step 1 replicated them. Step 2 is alignment and formation of the tetrad. Step 3 is crossing over. Step 4 is separation of the homologous chromosomes. Step 5 is separation of the sister chromatids.
Meiosis Process
The first stage of meiosis is called prophase I, and this is when the tetrad forms. The two homologous chromosomes will align next to each other. But, since each is made up of two sister chromatids it will look like a group of four. In card version: the two fives of clubs stapled together are aligned with the two fives of diamonds that are also stapled together.
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http://www.hematology.org/Patients/Basics/
Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets.
FOUR HORNS
https://en.wikipedia.org/wiki/Styracosaurus
Individuals of the Styracosaurus genus were approximately 5.5 metres (18 ft) long as adults and weighed around 2.7 tonnes.[2] The skull was massive, with a large nostril, a tall straight nose horn, and a parietosquamosal frill (a neck frill) crowned with at least four large spikes. Each of the four longest frill spines was comparable in length to the nose horn, at 50 to 55 centimetres long (19.7 to 21.7 in).[3] The nasal horn is estimated at 57 centimeters long (19.7 in) in the type specimen,[4] but the horn is only partially complete. Based on other nasal horn cores from Styracosaurus and Centrosaurus, this horn may have come to a rounded point at around half of that length.[5]
Aside from the large nasal horn and four long frill spikes, the cranial ornamentation was variable. Some individuals had small hook-like projections and knobs at the posterior margin of the frill, similar to but smaller than those in Centrosaurus. Others had less prominent tabs. Some, like the type individual, had a third pair of long frill spikes. Others had much smaller projections, and small points are found on the side margins of some but not all specimens. Modest pyramid-shaped brow horns were present in subadults, but were replaced by pits in adults.[5] Like most ceratopsids, Styracosaurus had large fenestrae (skull openings) in its frill. The front of the mouth had a toothless beak.
http://www.americanscientist.org/bookshelf/pub/darwins-islands
The section of the book detailing Darwin’s time in the Galápagos is divided into four chapters, each devoted to one of the four islands he visited—Chatham (San Cristóbal), Charles (Floreana), Albemarle (Isabela) and James (Santiago). A faithful, detailed recreation of Darwin’s course once ashore on each island had never before been attempted. The authors went about ascertaining what paths Darwin took by referring to his unpublished geology notes, Captain Robert FitzRoy’s log of the Beagle and the nautical charts of the area prepared by the crew, and by relying on their own familiarity with the topography, ecology, habitats and distribution of organisms on each of the four islands. Here they explain their rationale and their goals:
FOUR ELEMENTS CALLED CHON MAKE UP 96 PERCENT OF BODY
https://askabiologist.asu.edu/content/atoms-life
The Top Four Elements Found in the Human Body
Of the elements found in the human body, four of them make up the largest percentage of our body weight (96.2%). The four elements are oxygen, hydrogen, carbon, nitrogen. Before you start thinking we should float away with all the oxygen, hydrogen, and nitrogen atoms, remember that the oxgen molecules are mainly part of the water in our body (H2O). In fact, over half of the human body is made up of water (50-70%).
FOUR LINEAGES
https://en.wikipedia.org/wiki/Dobsonfly
There are about sixty species of dobsonflies.[1] Contreras-Ramos [16] suggests nine genera within Corydalinae, divided into four lineages. Working from "most basal" to "most derived" lineages, there are:
The Protohermes lineage, containing the genera Neurhermes and Protohermes, distributed from Northwest India to Indonesia, China, and Japan.
The Chloroniella lineage, containing the monotypic genus Chloroniella, found only in South Africa.
The Nevromus lineage, containing the genera Acanthacorydalis, Nevromus, and Neoneuromus, distributed from Northwest India to Southeast Asia.
The Corydalus lineage, containing the genera Platyneuromus, Chloronia, and Corydalus, distributed from southern Canada down to northern Argentina and south-east Brazil.
https://en.wikipedia.org/wiki/Evolution_of_birds
Four distinct lineages of bird survived the Cretaceous-Tertiary extinction event 66 million years ago, giving rise to ostriches and relatives (Paleognathae), ducks and relatives (Anseriformes), ground-living fowl (Galliformes), and “modern birds” (Neoaves).
FOUR SPORES TETRADS
https://en.wikipedia.org/wiki/Spore
Under high magnification, spores can be categorized as either monolete spores or trilete spores. In monolete spores, there is a single line on the spore indicating the axis on which the mother spore was split into four along a vertical axis. In trilete spores, all four spores share a common origin and are in contact with each other, so when they separate, each spore shows three lines radiating from a center pole.
Spore tetrads and trilete spores[edit]
Main article: Evolutionary history of plants
[icon] This section needs expansion. You can help by adding to it. (August 2008)
Envelope-enclosed spore tetrads are taken as the earliest evidence of plant life on land,[4] dating from the mid-Ordovician (early Llanvirn, ~470 million years ago), a period from which no macrofossils have yet been recovered.[5] Individual trilete spores resembling those of modern cryptogamic plants first appeared in the fossil record at the end of the Ordovician period.[6]
FOUR GROUPS
https://en.wikipedia.org/wiki/Bumblebee
The bumblebee tribe Bombini is one of four groups of corbiculate bees (those with pollen baskets) in the Apidae, the others being the Apini (honeybees), Euglossini (orchid bees), and Meliponini (stingless bees). The corbiculate bees are a monophyletic group. Advanced eusocial behaviour appears to have evolved twice in the group, giving rise to controversy, now largely settled, as to the phylogenetic origins of the four tribes; it had been supposed that eusocial behaviour had evolved only once, requiring the Apini to be close to the Meliponini, which they do not resemble. It is now thought that the Apini (with advanced societies) and Euglossini are closely related, while the primitively eusocial Bombini are close to the Meliponini, which have somewhat more advanced eusocial behaviour. Sophie Cardinal and Bryan Danforth comment that "While remarkable, a hypothesis of dual origins of advanced eusociality is congruent with early studies on corbiculate morphology and social behavior."[10] Their analysis, combining molecular, morphological and behavioural data, gives the following cladogram:[10]
Corbiculate bees
Apini (honeybees)
Euglossini (orchid bees)
Bombini (bumblebees)
Meliponini (stingless bees)
FOUR RINGS CORE OF ANTIBIOTIC FAMILIES
https://en.wikipedia.org/wiki/Beta-lactam
A beta-lactam (β-lactam) ring is a four-membered lactam.[1] (A lactam is a cyclic amide.) It is named as such because the nitrogen atom is attached to the β-carbon atom relative to the carbonyl. The simplest β-lactam possible is 2-azetidinone.
Contents [hide]
1 Clinical significance
2 History
3 Synthesis
4 Reactivity
5 Other applications
6 See also
7 References
8 External links
Clinical significance[edit]
Penicillin core structure
The β-lactam ring is part of the core structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems, and monobactams, which are, therefore, also called β-lactam antibiotics. Nearly all of these antibiotics work by inhibiting bacterial cell wall biosynthesis. This has a lethal effect on bacteria. Bacteria do, however, contain within their populations, in smaller quantities, bacteria that are resistant against β-lactam antibiotics. They do this by expressing one of many β-lactamase genes. More than 1,800 different β-lactamase enzymes have been documented in various species of bacteria.[2] These enzymes vary widely in their chemical structure and catalytic efficiencies.[3] When bacterial populations have these resistant subgroups, treatment with β-lactam can result in the resistant strain becoming more prevalent and therefore more virulent.
https://en.wikipedia.org/wiki/Four-toed_hedgehog
The four-toed hedgehog (Atelerix albiventris), or African pygmy hedgehog, is a species of hedgehog found throughout much of central and eastern Africa.
FOUR KNOWN HISTAMINE RECEPTORS
https://en.wikipedia.org/wiki/Histamine_receptor
The histamine receptors are a class of G protein–coupled receptors which bind histamine as their primary endogenous ligand.[1]
There are four known histamine receptors:
H1 receptor
H2 receptor
H3 receptor
H4 receptor
THERE ARE FOUR SUBTYPES AND THEY ARE TETRAMERS- TETRA IS FOUR- THEY HAVE FOUR SUBUNITS WITH FOUR DOMAIN LAYERs
https://en.wikipedia.org/wiki/Ionotropic_glutamate_receptor
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that are activated by the neurotransmitter glutamate.[1] They mediate the majority of excitatory synaptic transmission throughout the central nervous system and are key players in synaptic plasticity, which is important for learning and memory. iGluRs have been divided into four subtypes on the basis of their ligand binding properties (pharmacology) and sequence similarity: AMPA receptors, kainate receptors, NMDA receptors and delta receptors (see below).[2]
iGluRs are tetramers (they are formed of four subunits). All subunits have a shared architecture with four domain layers: two extracellular clamshell domains called the N-terminal domain (NTD) and ligand-binding domain (LBD; which binds glutamate), the transmembrane domain (TMD) that forms the ion channel, and an intracellular C-terminal domain (CTD).[5]
The retina is a thin (~0.25 mm) layer of neural tissue that lines the back of the eye. It is part of the brain (central nervous system) displaced into the eye during development. In addition to the light-sensitive photoreceptor cells – the rods and cones - the retina contains four basic classes of neurons – horizontal, bipolar, amacrine and ganglion cells – along with one major type of glial cell – the Müller cell
http://www.scholarpedia.org/article/Retina
Although there are just four basic classes of retinal neurons in addition to the photoreceptors, many neuronal types exist in each of these classes
FOUR PARTS
https://en.wikipedia.org/wiki/Middle_cerebral_artery
The middle cerebral artery can be classified into 4 parts:[2]
M1: The sphenoidal segment, so named due to its origin and loose lateral tracking of the sphenoid bone. Although known also as the horizontal segment, this may be misleading since the segment may descend, remain flat, or extend posteriorly the anterior (dorsad) in different individuals. The M1 segment perforates the brain with numerous anterolateral central (lateral lenticulostriate) arteries, which irrigate the basal ganglia.
M2: Extending anteriorly on the insula, this segment in known as the insular segment. It is also known as the Sylvian segment when the opercular segments are included. The MCA branches may bifurcate or sometimes trifurcate into trunks in this segment which then extend into branches that terminate towards the cortex.
M3: The opercular segments and extends laterally exteriorly from the insula towards the cortex. This segment is sometimes grouped as part of M2.
M4: These finer terminal or cortical segments irrigate the cortex. They begin at the external of the Sylvian fissure and extend distally away on the cortex of the brain.
FOUR SUBUNITS
https://en.wikipedia.org/wiki/L-type_calcium_channel
The L-type calcium channel (also known as the dihydropyridine channel, or DHP channel) is part of the high-voltage activated family of voltage-dependent calcium channel.[2] "L" stands for long-lasting referring to the length of activation. This channel has four subunits (Cav1.1, Cav1.2, Cav1.3, Cav1.4).
https://bmcmolbiol.biomedcentral.com/articles/10.1186/1471-2199-12-33
CRUCIFORM
Cruciform structures are a common DNA feature important for regulating biological processes
Václav BrázdaEmail author, Rob C Laister, Eva B Jagelská and Cheryl Arrowsmith
BMC Molecular Biology201112:33
DOI: 10.1186/1471-2199-12-33© Brázda et al; licensee BioMed Central Ltd. 2011
Received: 21 February 2011Accepted: 5 August 2011Published: 5 August 2011
Abstract
DNA cruciforms play an important role in the regulation of natural processes involving DNA. These structures are formed by inverted repeats, and their stability is enhanced by DNA supercoiling. Cruciform structures are fundamentally important for a wide range of biological processes, including replication, regulation of gene expression, nucleosome structure and recombination. They also have been implicated in the evolution and development of diseases including cancer, Werner's syndrome and others.
Cruciform structures are targets for many architectural and regulatory proteins, such as histones H1 and H5, topoisomerase IIβ, HMG proteins, HU, p53, the proto-oncogene protein DEK and others. A number of DNA-binding proteins, such as the HMGB-box family members, Rad54, BRCA1 protein, as well as PARP-1 polymerase, possess weak sequence specific DNA binding yet bind preferentially to cruciform structures. Some of these proteins are, in fact, capable of inducing the formation of cruciform structures upon DNA binding. In this article, we review the protein families that are involved in interacting with and regulating cruciform structures, including (a) the junction-resolving enzymes, (b) DNA repair proteins and transcription factors, (c) proteins involved in replication and (d) chromatin-associated proteins. The prevalence of cruciform structures and their roles in protein interactions, epigenetic regulation and the maintenance of cell homeostasis are also discussed.
https://en.wikipedia.org/wiki/Deep_cerebellar_nuclei
The cerebellum has four deep cerebellar nuclei embedded in the white matter in its center.
https://en.wikipedia.org/wiki/Araneus_quadratus
Araneus quadratus, the four-spot orb-weaver, is a common orb-weaver spider found in Europe and Central Asia, and as far as the Kamchatka Peninsula and Japan.[1] Females can reach 17 mm in length, especially when gravid, males approximately half that. They are quite variable in appearance, ranging from brown to bright orange or green, but they always have the characteristic four white spots on the abdomen. The darker color morphs are easiest to identify, due to the contrast between the white spots and the rest of the body. The legs are sometimes brightly striped.
Each crew member's uniform is decorated with insignia which, akin to naval uniforms, represents his or her duties on board the aircraft. The airline captain's insignia corresponds to the naval captain's insignia, such as four stripes on the shoulder epaulets and four stripes on the blazer arms. First officer's insignia corresponds to the naval commander uniform, bearing three stripes on shoulder epaulets and blazer arms. (On some airlines, less experienced first officers will wear two stripes.) ACM insignia is similar to naval lieutenant's uniforms, with two stripes.
Pilots also typically wear a winged badge indicating their qualification to fly and their seniority. The color typically matches the sleeve stripe color, and the badge may be a metal pin or an embroidered patch. They generally follow the pattern of having the corporate logo in the center. For US-based carriers, a captain generally has a star enclosed in a laurel wreath on top, similar to a command pilot in the US Air Force. A first officer has only a star, similar to a senior pilot in the USAF.
Uniform itemCaptainFirst OfficerSecond Officer/
Additional Crew MemberThird officer/
Trainee
Blazer/epaulets4 stripes3 stripes2 stripes1 stripe
Qualification badgeWings with a star
enclosed in a laurel wreathWings with a starWingsWings
KANT FOUR RACES
https://en.wikipedia.org/wiki/Scientific_racism
Immanuel Kant (1724–1804) was a German philosopher who encouraged the examination of man's inner self rather than making inferences about the inner self based upon the exterior physical self.[35] In 1775, Kant published On the Different Races of Man (Über die verschiedenen Rassen der Menschen), which proposed natural or purposive causes of variation, as opposed to mechanical law or a product of chance. He distinguished four fundamental races: whites, blacks, Kalmuck, and Hindustanic, and attributed the variation to differences in environment and climate, such as the air and sun, but clarified by saying that the variation served a purpose and was not purely superficial. Kant argued that human beings were equipped with the same seeds (Keime) and the natural predispositions or characteristics (Anlagen) that when expressed were dependent upon climate and served a purpose due to the circumstance. After this process had occurred, it was also irreversible. Therefore, race could not be undone by changes in climate. "Whichever germ was actualized by the conditions, the other germs would retire into inactivity." Kant stated:
The yellow Indians do have a meagre talent. The Negroes are far below them, and at the lowest point are a part of the American people.[36]
TETRA IS FOUR
https://en.wikipedia.org/wiki/Tiger_barb
Puntius tetrazona,[1] the tiger barb or Sumatra barb, is a species of tropical cyprinid fish
The tiger barb can grow to about 7-10 centimeters long (2.75 – 4 in) and 3-4 centimeters wide,(1.18 in), although they are often smaller when kept in captivity. Some can grow to around 13 centimeters as well. Native fish are silver to brownish yellow with four vertical black stripes and red fins and snout. The green tiger barb is the same size and has the same nature as the normal barb, but has a green body. The green tiger barb, often called the moss green tiger barb, can vary considerably in how green it looks; to some people it looks nearly black. Albino barbs are a light yellow with four barely visible stripes.
TIGERS HAVE FOUR STRIPES ON THEIR FOREHEADS WHICH REPRESENTS KING- AND THEY ARE ONE OF THE FOUR SUPERINTELLIGENT ANIMALS
https://en.wikipedia.org/wiki/Tiger_in_Chinese_culture
The tiger represents the masculine principle in nature and is king of all the animals, as shown by the four stripes on his forehead, which form the character Wang (王), or King. The tiger is regarded as one of the four super-intelligent creatures, along with the dragon, phoenix and tortoise; for centuries, the four have been a major design motif in Chinese art.
The four-lined wrasse, Pseudocheilinus tetrataenia, is a species of wrasse native to the Pacific Ocean. It inhabits coral reefs at depths from 6 to 44 m (20 to 144 ft). This species can grow to 7.5 cm (3.0 in) in total length. It can be found in the aquariumtrade.[2]
Ameiva quadrilineata (four-lined ameiva or four-lined whiptail) is a species of whiptail lizard found in western Panama, Costa Rica, and southeast Nicaragua.[2]
https://en.wikipedia.org/wiki/Ameiva_quadrilineata
Description[edit]
Brown coloured with four light lines running down the back. Similar species, Ameiva festiva. Lives in open habitats. Juveniles have metallic-blue tails.[3]
An MHC tetramer assay or simply tetramer assay or tetramer stain is a procedure developed at Stanford University School of Medicine used to detect and quantify T-cells that are specific for a given antigen within a blood sample.
https://en.wikipedia.org/wiki/Human_genetics
Four different traits can be identified by pedigree chart analysis: autosomal dominant, autosomal recessive, x-linked, or y-linked. Partial penetrance can be shown and calculated form pedigrees. Penetrance is the percentage expressed frequency with which individuals of a given genotype manifest at least some degree of a specific mutant phenotype associated with a trait.
I'm a paragraph. Click here to add your own text and edit me. It's easy.
https://en.wikipedia.org/wiki/History_of_horse_domestication_theories
American paleontologist Deb Bennett[5][6] postulated that the early form of E. caballus developed into seven subspecies,[7] of which four supposedly contributed most to the ancestry of the domesticated horse, both directly and via assorted crossbred lineages between them.[8] These were:
"Warmblood subspecies", Equus caballus mosbachensis, the oldest hypothetical subspecies, supposedly ancestor of the Latvian horse, Groningen horse and some warmblood breeds.
"Draft subspecies", Equus caballus caballus, ancestor of the Exmoor Pony, Shetland pony, Suffolk Punch and Belgian horse.
"Oriental subspecies", Equus caballus pumpelli, adapted to arid climates, thought to be the progenitor of the modern Arabian horse, Plateau Persian and Marwari horse.
"Tarpan", Equus caballus gmelini[9] or Equus caballus ferus, supposed ancestor of Przewalski's Horse as well as the Konik, Vyatka horse, Hucul and most Mongolian horses.
https://en.wikipedia.org/wiki/History_of_horse_domestication_theories
European scholars such as Jimmy Speed, Ruy d'Andrade, Hermann Ebhardt and Edward Skorkowski, postulated four basic body types, which were not considered to be named species.[4] They were:
Pony Type 1, in northwestern Europe, resistant to cold and wet, similar to the modern Exmoor pony
Pony Type 2, in northern Eurasia, larger than type 1, resistant to cold, similar to the modern Highland pony and Fjord horse
Horse Type 1, in central Asia, resistant to heat and drought, similar to the modern Sorraia and Akhal-Teke
Horse Type 2, in western Asia, small and fine-boned, resistant to heat, similar to the modern Caspian horse.
http://www.reptileknowledge.com/reptiles.php
Reptile Classification
Today, scientists classify reptiles into four major groups known as "orders." These four reptile orders are as follows:
Crocodilia — crocodiles, gharials, caimans and alligators: 23 species
Sphenodontia — tuataras from New Zealand: 2 species
Squamata — lizards, snakes and amphisbaenids ("worm-lizards"): about 7,900 species
Testudines — turtles and tortoises: approximately 300 species
Read more: http://www.reptileknowledge.com/reptiles.php#ixzz4arzOt4Y7
https://en.wikipedia.org/wiki/Gastrointestinal_tract
Upon dissection, the duodenum may appear to be a unified organ, but it is divided into four segments based upon function, location, and internal anatomy. The four segments of the duodenum are as follows (starting at the stomach, and moving toward the jejunum): bulb, descending, horizontal, and ascending.
https://en.wikipedia.org/wiki/Stomach
In classical anatomy, the stomach is divided into four sections, beginning at the Gastric cardia,[6] each of which has different cells and functions.
The cardia is where the contents of the oesophagus empty into the stomach. The cardia is defined as the region following the "z-line" of the gastroesophageal junction, the point at which the epithelium changes from stratified squamous to columnar. Near the cardia is the lower esophageal sphincter.[7]
The fundus (from Latin, "bottom") is formed by the upper curvature of the organ.
The body is the main, central region.
The pylorus (from Greek, "gatekeeper") is the lower section of the organ that facilitates emptying the contents into the small intestine.
Tetrad of Narcolepsy
https://infogr.am/the-holy-tetrad-of-narcolepsy
EDS
Sleep Paralysis
Cataplexy
Hallucinations
https://en.wikipedia.org/wiki/Brain_types
Jonathan P. Niednagel developed a system that categorizes brain types, which he claims was inspired by the Myers Briggs and Socionics personality models. They are
Square 1: Empirical-Animate' types (FEAL, FEAR, BEAL, BEAR), are thought to be the best in the region of the brain responsible for gross motor skills
Square 2: EI, or 'Empirical-Inanimate' types (FEIL, FEIR, BEIL, BEIR) are believed to excel with fine motor skills of the four groups
Square 3: CA, or 'Conceptual-Animate' types (FCAL, FCAR, BCAL, BCAR), excel in the auditory cortex
Square 4:CI, or 'Conceptual-Inanimate' types (FCIL, FCIR, BCIL, BCIR), are thought to be the best in the cerebral cortex, where there is abstract levels of reasoning
Four Classes of Biological Macromolecules
There are four major classes of biological macromolecules:
carbohydrates
lipids
proteins
nucleic acids
Source: Boundless. “Types of Biological Macromolecules.” Boundless Biology Boundless, 26 May. 2016. Retrieved 22 Mar. 2017 from https://www.boundless.com/biology/textbooks/boundless-biology-textbook/biological-macromolecules-3/synthesis-of-biological-macromolecules-53/types-of-biological-macromolecules-293-11426/
https://en.wikipedia.org/wiki/Cerebrum
The Cerebrum: The cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes": the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. Here is a visual representation of the cortex:
FOUR STAGES
Since the discovery of CTE in American football legend Mike Webster, whose experience of CTE was immortalised in the recent Hollywood movie “Concussion”, many other cases are being unearthed within the sport and our knowledge of the disease is expanding. Work from Neurophysiologist Dr Ann McKee has identified four stages of the disease:
http://sportsneuropsychology.co.uk/cte
Figure 2 - The four stages of CTE development
So what we know is that CTE is a degenerative disease affecting the brains of those who sustain frequent head trauma and concussion. Importantly, recent evidence has also suggested that a build of head blows which do not necessarily cause a concussion (sub-concussive blows) can have a similar such effect.
FOUR COAT DIVISIONS
https://en.wikipedia.org/wiki/Persian_cat
The International Cat Association (TICA) groups the breed into three coat-pattern divisions for judging at cat shows: traditional (with stable, rich colors), sepia ("paler and warmer than the traditional equivalents", and darkening a bit with age), and mink (much lighter than sepia, and developing noticeably with age on the face and extremities). If classified as the Himalayan sub-breed, full point coloration is required, the fourth TICA color division, with a "pale and creamy colored" body even lighter than mink, with intense coloration on the face an extremities. The four TICA categories are essentially a graduated scale of color distribution from evenly colored to mostly colored only at the points. Within each, the coloration may be further classified as solid, tortoiseshell (or "tortie"), tabby, silver or smoke, solid-and-white, tortoiseshell-and-white, tabby-and-white, or silver/smoke-and-white, with various specific colors and modifiers (e.g. chocolate tortoishell point, or fawn shaded mink marbled tabby-torbie). TICA-recognized tabby patterns include classic, mackerel, marbled, spotted, and ticked (in two genetic forms), while other patterns include shaded, chinchilla, and two tabbie-tortie variations, golden, and grizzled. Basic colors include white, black, brown, ruddy, bronze, "blue" (grey), chocolate, cinnamon, lilac, fawn, red, cream, with a silver or shaded variant of most. Not counting bi-color (piebald) or parti-color coats, nor combinations that are genetically impossible, there are nearly 1,000 named coat pattern variations in the TICA system for which the Persian/Himalayan qualifies. The Exotic Shorthair sub-breed qualifies for every cat coat variation TICA recognizes.[13]
Grand Champion Topknot James Bond of Lions & Owls. A solid black, 1 year old Persian cat with brilliant copper eyes. This cat is in kitten coat and the color of the coat will darken as the kitten coat is shed and the adult coat grows in. Note the immense ruff, small round ears, heavy-boned, cobby body, and nose that is short, snub, and broad, with “break” centered between the eyes.
The Cat Fanciers' Association (CFA), of the United States, also groups the breed into four coat-pattern divisions, but differently: solid, silver and golden (including chinchilla and shaded variants, and blued subvariants), shaded and smoke (with several variations of each, and a third subcategorization called shell), tabby (only classic, mackerel, and patched [spotted], in various colors), parti-color (in four classes, tortoiseshell, blue-cream, chocolaet tortie, and lilac-cream, mixed with other colors), calico and bi-color (in around 40 variations, broadly classified as calico, dilute calico, and bi-color), and Himalayan (white-to-fawn body with point coloration on the head, tail and limbs, in various tints). CFA base colors are white, black, blue, red, cream, chocolate, and lilac. There are around 140 named CFA coat patterns for which the Himalayan qualifies, and 20 for the Himalayan subbreed.[31] These coat patterns encompass virtually all of those recognized by CFA for cats generally. Any Persian permissible in TICA's more detailed system would probably be accepted in CFA's, simply with a more general name, though the organizations do not mix breed registries.
FOUR TYPES OF HORMONES IN VERTEBRATES- I LEARNED ABOUT THIS IN BIOLOGY CLASS
https://simple.wikipedia.org/wiki/Hormone
There are four types of hormones in most vertebrates. They are grouped by the chemicals from which they are made.
Steroid hormones – these are made from cholesterol. Examples of steroid hormones include the sex hormones estradiol and testosterone as well as the stress hormone cortisol.[3]
Eicosanoids: these are lipid hormones – hormones made from lipids, kinds of fats. These are mostly hormones that send messages near the cell that makes the hormones.
Amino acid derived. Melatonin works on the brain, and thyroxine acts on almost all cells in the body. Many of these hormones are neurotransmitters, hormones that one nerve cell sends to another nerve cell.
Peptides, polypeptides and proteins – small peptide hormones include TRH and vasopressin. Peptides composed of scores or hundreds of amino acids are referred to as proteins. Examples of protein hormones include insulin and growth hormone. More complex protein hormones bear carbohydrate side-chains and are called glycoprotein hormones. Luteinizing hormone, follicle-stimulating hormone and thyroid-stimulating hormone are examples of glycoprotein hormones.
I SAT IN ON A BIOCHEMISGRY CLASS AT UCSD IT WAS ALL THE QUADRANT MODEL AND THE RAMACHANDRAN PLOT WAS TAUGHT MOST OF THE TIME WHICH WAS A QUADRANT
- THE FOURTH PART DIFFERENT- I ALSO DISCUSSED I CAN'T REMEMBER THE EXAMPLES NOW BUT IN MY CHEMISTRY CLASSES THE TEACHER WOULD DRAW QUADRANTS AND SAY STUFF LIKE "ONLY EVEN NEGATIVE NUCLEAR NUMBERS IN THE FOURTH QUADRANT WORK WE DON'T KNOW WHY"- IN MY HEAD I'D BE LIKE- BECAUASE ITS THE FOURTH QUADRANT THATS WHY
https://en.m.wikipedia.org/wiki/Ramachandran_plot#
In my qmr books i discussed the ramachandran plot is a quadrant with the fourth square being different as well as many other things in biology you would be amazed ((i went to classes all day everyday in biology and chemistry it was all quadrant model i wrote it in notebooks but i havent gone through the notebooks yet)
FOUR CHAINS
https://en.wikipedia.org/wiki/Chain_of_survival
The chain of survival refers to a series of actions that, properly executed, reduce the mortality associated with cardiac arrest.[1][2] Like any chain, the chain of survival is only as strong as its weakest link.[1][2] The four interdependent links in the chain of survival are early access, early CPR, early defibrillation, and early advanced cardiac life support
In July 2014, a 5 year old white tigress of Nandankanan Zoological Park gave birth to four cubs and of these one was black. This was the first instance of birth of a black tiger in captivity in India and second recorded instance internationally.[15][16]
https://en.wikipedia.org/wiki/Rhabdomys_dilectus
The mesic four-striped grass rat (Rhabdomys dilectus) is a species of rodent in the family Muridae.[2]
16 ROUNDED RIBS 16 THREADS
https://en.wikipedia.org/wiki/Glyphostoma_gratula
The transverse sculpture consists of eleven to (on the body whorl) sixteen slightly oblique rounded ribs, faintly evident across the band and anteriorly extending to the suture, or, on the body whorl, well forward on the siphonal canal. These are crossed by (on the smaller whorls) two to four or (on the last one) sixteen rounded threads, distinct in the interspaces and slightly swollen on the tops of the ribs where they cross
FOUR GROUPS
Eagles are often informally divided into four groups.[note 1][17]
https://en.wikipedia.org/wiki/Eagle
The snake eagles are placed in the subfamily Circaetinae. The fish eagles, booted eagles, and harpy eagles have traditionally been placed in the subfamily Buteoninae together with the buzzard-hawks (buteonine hawks) and harriers. Some authors may treat these groups as tribes of the Buteoninae; Lerner & Mindell[18] proposed separating the eagle groups into their own subfamilies of Accipitridae.
FOUR SPECIES THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Peccary
Three (possibly four) living species of peccaries are found from the southwestern United States through Central America and into South America and Trinidad.
The collared peccary (Pecari tajacu) or "musk hog", referring to the animal's scent glands, occurs from the southwestern United States into South America and the island of Trinidad. The coat consists of wiry peppered black, gray, and brown hair with a lighter colored "collar" circling the shoulders. They bear young year-round, but most often between November and March, with the average litter size consisting of two to three piglets. They are found in all kinds of habitats, from arid scrublands to humid tropical rain forests. The collared peccary is well adapted to habitat disturbed by humans, merely requiring sufficient cover; they can be found in cities and agricultural land throughout their range. Notable populations exist in the suburbs of Phoenix and Tucson, Arizona, where they feed on ornamental plants and other cultivated vegetation.[12][13] Collared peccaries are generally found in bands of 8 to 15 animals of various ages. They defend themselves if they feel threatened, but otherwise tend to ignore humans.
A second species, the white-lipped peccary (Tayassu pecari), is mainly found in rainforests of Central and South America, but also known from a wide range of other habitats such as dry forests, grasslands, mangrove, cerrado, and dry xerophytic areas.[14]
The third species, the Chacoan peccary (Catagonus wagneri), is the closest living relative to the extinct Platygonus pearcei. It is found in the dry shrub habitat or Chaco of Paraguay, Bolivia, and Argentina. The Chacoan peccary has the unusual distinction of having been first described based on fossils and was originally thought to be only an extinct species. In 1975, the animal was discovered in the Chaco region of Paraguay. The species was well known to the native people.
A fourth as yet unconfirmed species, the giant peccary (Pecari maximus), was described from the Brazilian Amazon and north Bolivia[15] by Dutch biologist Marc van Roosmalen. Though relatively recently discovered, it has been known to the local Tupi people as caitetu munde, which means "great peccary which lives in pairs".[16][17] Thought to be the largest extant peccary, it can grow to 1.2 m (3.9 ft) in length. Its pelage is completely dark gray, with no collars whatsoever. Unlike other peccaries, it lives in pairs, or with one or two offspring. However, the scientific evidence for considering it as a species separate from the collared peccary has later been questioned,[18][19] leading the IUCN to treat it as a synonym.[20]
http://research.omicsgroup.org/index.php/Swastika
In Life's Other Secret (1999), Ian Stewart suggests the ubiquitous swastika pattern arises when parallel waves of neural activity sweep across the visual cortex during states of altered consciousness, producing a swirling swastika-like image, due to the way quadrants in the field of vision are mapped to opposite areas in the brain.[16]
http://turing.manhattan.edu/~ocoppola01/movement.html
https://en.wikipedia.org/wiki/Horse_gait
All horses move naturally with four basic gaits: the four-beat walk, which averages 6.4 kilometres per hour (4.0 mph); the two-beat trot or jog at 13 to 19 kilometres per hour (8.1 to 11.8 mph) (faster for harness racing horses); the canter or lope, a three-beat gait that is 19 to 24 kilometres per hour (12 to 15 mph); and the gallop.[80] The gallop averages 40 to 48 kilometres per hour (25 to 30 mph),[81] but the world record for a horse galloping over a short, sprint distance is 88 kilometres per hour (55 mph).[82] Besides these basic gaits, some horses perform a two-beat pace, instead of the trot.[83] There also are several four-beat "ambling" gaits that are approximately the speed of a trot or pace, though smoother to ride. These include the lateral rack, running walk, and tölt as well as the diagonal fox trot. Ambling gaits are often genetic in some breeds, known collectively as gaited horses. Often, gaited horses replace the trot with one of the ambling gaits.
https://www.coursehero.com/…/receptors-in-the-skin-are-sen…/
https://books.google.com/books…
Purebred dogs of one breed are genetically distinguishable from purebred dogs of other breeds, but the means by which kennel clubs classify dogs is unsystematic. Systematic analyses of the dog genome has revealed only four major types of dogs that can be said to be statistically distinct.These include the "old world dogs" (e.g., Malamute and Shar Pei), "Mastiff"-type (e.g., English Mastiff), "herding"-type (e.g., Border Collie), and "all others" (also called "modern"- or "hunting"-type).
I had an English Mastiff growing up.
https://en.wikipedia.org/wiki/Shark_attack
The fourth is always different (the white tip)
Only a few sharks are dangerous to humans. Out of more than 480 shark species, only three are responsible for two-digit number of fatal unprovoked attacks on humans: the great white, tiger and bull; however, the oceanic whitetip has probably killed many more castaways, not recorded in the statistics.
The great white shark is one of only four kinds of sharks that have been involved in a significant number of fatal unprovoked attacks on humans.
https://en.wikipedia.org/wiki/2010_Sharm_El_Sheikh_shark_attacks
The 2010 Sharm el-Sheikh shark attacks were a series of attacks by sharks on swimmers off the Red Sea resort of Sharm el-Sheikh, Egypt. On 1 December 2010, three Russians and one Ukrainian were seriously injured within minutes of each other. This was the first four squares. The fourth was different. After this the beaches were closed for a long time and authorities went on a killing spree killing all of the sharks that they could find in the area. Then the beaches were reopened and right when they were reopeneda 5 December 2010 a German woman was killed, when they were attacked while wading or snorkeling near the shoreline. The attacks were described as "unprecedented" by shark experts. It was seen as bizarre as nothing like that had ever happened before. The fifth is always ultra transcendent the fourth is always different.
In response to the attacks, beaches in the popular tourist resort were closed for over a week, dozens of sharks were captured and killed, and the local government issued new rules banning shark feeding and restricting swimming. A variety of theories were put forward to explain the attacks. By late December 2010, the most plausible theory to emerge was that the dumping of sheep carcasses in the Red Sea by a livestock transport during the Islamic festival of Eid al-Adha had attracted the sharks to the shore. Other theories focused on overfishing in the Red Sea or on the illegal or inadvertent feeding of sharks or smaller fish close to the shore, which produced scents that attracted more sharks.
The attacks fit the quadrant model pattern.
The attacks also sparked conspiracy theories about possible Israeli involvement. Egyptian television broadcast claims that Israeli divers captured a shark with a GPS unit planted on its back. Describing the theory as "sad", Professor Mahmoud Hanafy of the Suez Canal University pointed out that GPS devices are used by marine biologists to track sharks, not to remote-control them. Governor Mohamed Abdel Fadil Shousha himself ultimately said he thought the dumping of sheep carcasses during the Islamic festival of Eid al-Adha on 16 November was the most likely explanation.
These are the two very famous shark attack sprees and they fit the quadrant model pattern.
https://en.wikipedia.org/wiki/Prionailurus
Prionailurus is a genus of four species of small, spotted wild cats found in Asia.[2] They are typically forest-dwelling. Most are able to swim well; some species are semi-aquatic and feed mainly on fish and other aquatic animals.
I LEARNED ABOUT THIS IN BIOLOGY CLASS AT UCSD THE PROFESSOR SAID THAT THE DROSOPHILIA IS THE MODEL ORGANISM USED BY BIOLOGISTS BECAUSE IT IS SIMPLE IN THAT IT HAS FOUR PAIRS OF CHROMOSOMES- THE FOURTH IS DIFFERENT- THE FOURTH IS "SO TINY IT IS OFTEN IGNORED"
https://en.wikipedia.org/wiki/Drosophila_melanogaster
It has only four pairs of chromosomes: three autosomes, and one pair of sex chromosomes.
D. melanogaster continues to be widely used for biological research in studies of genetics, physiology, microbial pathogenesis, and life history evolution. It is typically used because it is an animal species that is easy to care for, has four pairs of chromosomes, breeds quickly, and lays many eggs.[
The genome of D. melanogaster (sequenced in 2000, and curated at the FlyBase database[27]) contains four pairs of chromosomes: an X/Y pair, and three autosomes labeled 2, 3, and 4. The fourth chromosome is so tiny, it is often ignored, aside from its important eyeless gene. The D. melanogaster sequenced genome of 139.5 million base pairs has been annotated[29] and contains around 15,682 genes according to Ensemble release 73. More than 60% of the genome appears to be functional non-protein-coding DNA[30] involved in gene expression control. Determination of sex in Drosophila occurs by the X:A ratio of X chromosomes to autosomes, not because of the presence of a Y chromosome as in human sex determination. Although the Y chromosome is entirely heterochromatic, it contains at least 16 genes, many of which are thought to have male-related functions.[31]
Four stages
https://en.wikipedia.org/wiki/Apical_dominance
Plant physiologists have identified four different stages the plant goes through after the apex is removed (Stages I-IV). The four stages are referred to as
lateral bud formation,
"imposition of inhibition" (apical dominance),
initiation of lateral bud outgrowth following decapitation, and
elongation and development of the lateral bud into a branch.
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https://en.wikipedia.org/wiki/Penicillin --- FOUR MEMBERED B- LACTAM RING--- PENICILIN REVOLUTIONIZED MEDICINE AND SAVED MANY PEOPLES LIVES IT HAS FOUR MEMBERED RING
MQr i put this in one of my first quadrant model books
Bacteria constantly remodel their peptidoglycan cell walls, simultaneously building and breaking down portions of the cell wall as they grow and divide. β-Lactam antibiotics inhibit the formation of peptidoglycan cross-links in the bacterial cell wall; this is achieved through binding of the four-membered β-lactam ring of penicillin to the enzyme DD-transpeptidase. As a consequence, DD-transpeptidase cannot catalyze formation of these cross-links, and an imbalance between cell wall production and degradation develops, causing the cell to rapidly die.
The term "penam" is used to describe the common core skeleton of a member of the penicillins. This core has the molecular formula R-C9H11N2O4S, where R is the variable side chain that differentiates the penicillins from one another. The penam core has a molecular weight of 243 g/mol, with larger penicillins having molecular weights near 450—for example, cloxacillin has a molecular weight of 436 g/mol. The key structural feature of the penicillins is the four-membered β-lactam ring; this structural moiety is essential for penicillin's antibacterial activity. The β-lactam ring is itself fused to a five-membered thiazolidine ring. The fusion of these two rings causes the β-lactam ring to be more reactive than monocyclic β-lactams because the two fused rings distort the β-lactam amide bond and therefore remove the resonance stabilisation normally found in these chemical bonds.[22]
FOUR STRIPES
https://en.wikipedia.org/wiki/Dascyllus_melanurus
Dascyllus melanurus, known commonly as the four stripe damselfish, blacktail dascyllus, humbug damselfish, blacktail damselfish, and blacktail humbug, is a species of fish in the family Pomacentridae. It is native to the western Pacific Ocean. It is sometimes kept as an aquarium pet.[1]
FOUR BRANCHES
https://en.wikipedia.org/wiki/Africanized_bee
The Western honey bee is native to the continents of Europe, Asia, and Africa. As of the early 1600s, the insect was introduced to North America, with subsequent introductions of other European subspecies two centuries later.[23] Since then, they have spread throughout the Americas. The 28 subspecies can be assigned to one of four major branches based on work by Ruttner and subsequently confirmed by analysis of mitochondrial DNA. African subspecies are assigned to branch A, northwest European subspecies to branch M, southwest European subspecies to branch C, and Mideast subspecies to branch O. The subspecies are grouped and listed. There are still regions with localized variations that may become identified subspecies in the near future, such as A. m. pomonella from the Tian Shan mountains, which would be included in the Mideast subspecies branch.
FOUR SUPER RADIATIONS OF INSECTS HAVE OCCURED- THESE FOUR GROUPS ARE MAJORITY OF INSECTS
https://en.wikipedia.org/wiki/Insect
Four super radiations of insects have occurred: beetles (evolved about 300 million years ago), flies (evolved about 250 million years ago), and moths and wasps (evolved about 150 million years ago).[17] These four groups account for the majority of described species. The flies and moths along with the fleas evolved from the Mecoptera.
12-16 spots
https://www.theguardian.com/…/ladybird-species-harlequin-uk…
The orange ladybird ( Halyzia sedecimguttata) has 12-16 white spots. It overwinters in leaf litter or sheltered positions on trees and eats mildews. Considered until 1987 an indicator of ancient woodland, it has become widespread since it became common on sycamores; it has recently moved on to ash trees. It is attracted to light and is often found in moth-traps
https://en.wikipedia.org/wiki/Diplura
The order Diplura is one of the four groups of hexapods, alongside insects, springtails and Protura. They are sometimes called "two-pronged bristletails".[3] Around 800 species have been described, of which around 70 occur in North America,[2] 12 in Great Britain[4] and two in Australia.[5]
Mitral cells receive input from at least four cell types: olfactory sensory neurons, periglomerular neurons, external tufted cells and granule cells.
Based on morphological diversity revealed by Golgi staining, dSA cells in the rodent olfactory bulb were initially defined belonging to one of four cell types: Blanes cells, Golgi cells, horizontal cells, and Cajal cells. Schneider and Macrides (1978) described the morphology and location of the various dSA cells in the hamster olfactory bulb. Blanes cells are mostly found in the GCL or the IPL and have the largest cell body (16–23 μm) of the four dSA cells. They also have stellate dendrites covered with many spines. Golgi cells likewise are found in the GCL. Their cell bodies are slightly smaller than those of Blanes cells (12–22 μm), and their dendrites rarely have spines. Both horizontal cells and Cajal cells have the smallest cell bodies (15–18 μm), are restricted to the IPL and MCL, and have smooth dendrites. To date, all dSA cells are considered to be GABAergic, as are their post-synaptic target cells. Recently, dSA cell morphologies were reconstructed after electrophysiological recording in a rat olfactory bulb slice (Eyre et al., 2008). Overall, the dendrites of all four dSA cell types were restricted to the layers below the MCL. Despite the Schneider and Macrides report of the extension of Cajal cell dendrites to the EPL, this was not described by Eyre et al. Although the input sources were not revealed in detail, both excitatory and inhibitory inputs apparently modulated the activity of dSA cells. http://journal.frontiersin.org/article/10.3389/fncir.2014.00098/full
https://en.wikipedia.org/wiki/Ingerophrynus_quadriporcatus
Ingerophrynus quadriporcatus is a species of toad in the Bufonidae family. Its common names are long-glanded toad,[4] four-ridged toad and greater Malacca toad. It is found in Peninsular Malaysia, Singapore, Borneo (Sabah, Brunei, Sarawak, and Kalimantan), Sumatra, and the Natuna Islands. Its natural habitats are swamp forests, but it has also been found on rubber plantations. It breeds in standing water.
Cockroaches are widespread, and are one of the hardest household pests to control. Four types of cockroaches cause problems for people. These are the four cockroaches known as pests.
German
American
Oriental
Brown Banded
NORMAL RHYTHME PRODUCES FOUR ENTITIES
https://en.wikipedia.org/wiki/Electrocardiography
Theory[edit]
QRS is upright in a lead when its axis is aligned with that lead's vector
Schematic representation of normal ECG
Interpretation of the ECG is ultimately that of pattern recognition. In order to understand the patterns found, it is helpful to understand the theory of what ECGs represent. The theory is rooted in electromagnetics and boils down to the four following points:
depolarization of the heart toward the positive electrode produces a positive deflection
depolarization of the heart away from the positive electrode produces a negative deflection
repolarization of the heart toward the positive electrode produces a negative deflection
repolarization of the heart away from the positive electrode produces a positive deflection
Thus, the overall direction of depolarization and repolarization produces a vector that produces positive or negative deflection on the ECG depending on which lead it points to. For example, depolarizing from right to left would produce a positive deflection in lead I because the two vectors point in the same direction. In contrast, that same depolarization would produce minimal deflection in V1 and V2 because the vectors are perpendicular and this phenomenon is called isoelectric.
Normal rhythm produces four entities — a P wave, a QRS complex, a T wave, and a U wave — that each have a fairly unique pattern.
The P wave represents atrial depolarization.
The QRS complex represents ventricular depolarization.
The T wave represents ventricular repolarization.
The U wave represents papillary muscle repolarization.
However, the U wave is not typically seen and its absence is generally ignored. Changes in the structure of the heart and its surroundings (including blood composition) change the patterns of these four entities.
Finally, a full interpretation of the ECG should be performed in a methodical manner to avoid overlooking small details that may change the overall interpretation. This is similar to interpretation of radiological studies.
TETRAPEPTIDE FOUR
https://en.wikipedia.org/wiki/CCK-4
Cholecystokinin tetrapeptide (CCK-4, Trp-Met-Asp-Phe-NH2) is a peptide fragment derived from the larger peptide hormone cholecystokinin. Unlike cholecystokin which has a variety of roles in the gastrointestinal system as well as central nervous system effects, CCK-4 acts primarily in the brain as an anxiogenic, although it does retain some GI effects, but not as much as CCK-8 or the full length polypeptide CCK-58.
CCK-4 reliably causes severe anxiety symptoms when administered to humans in a dose of as little as 50μg,[1] and is commonly used in scientific research to induce panic attacks for the purpose of testing new anxiolytic drugs.[2][3][4][5] Since it is a peptide, CCK-4 must be administered by injection, and is rapidly broken down once inside the body so has only a short duration of action,[6] although numerous synthetic analogues with modified properties are known.[7][8][9][10][11][12][13][14][15][16][17]
FOUR TYPES OF ADENOSINE RECEPTORS
https://en.wikipedia.org/wiki/Adenosine_receptor
In humans, there are four types of adenosine receptors. Each is encoded by a separate gene and has different functions, although with some overlap.[3] For instance, both A1 receptors and A2A play roles in the heart, regulating myocardial oxygen consumption and coronary blood flow, while the A2A receptor also has broader anti-inflammatory effects throughout the body.[4] These two receptors also have important roles in the brain,[5] regulating the release of other neurotransmitters such as dopamine and glutamate,[6][7][8] while the A2B and A3 receptors are located mainly peripherally and are involved in processes such as inflammation and immune responses.
Most older compounds acting on adenosine receptors are nonselective, with the endogenous agonist adenosine being used in hospitals as treatment for severe tachycardia (rapid heart beat),[9] and acting directly to slow the heart through action on all four adenosine receptors in heart tissue,[10] as well as producing a sedative effect through action on A1 and A2A receptors in the brain. Xanthine derivatives such as caffeine and theophylline act as non-selective antagonists at A1 and A2A receptors in both heart and brain and so have the opposite effect to adenosine, producing a stimulant effect and rapid heart rate.[11] These compounds also act as phosphodiesterase inhibitors, which produces additional anti-inflammatory effects, and makes them medically useful for the treatment of conditions such as asthma, but less suitable for use in scientific research.[12]
FOUR ZONES
A schematic diagram illustrating the axonal connectivity pattern between the olfactory epithelium and the olfactory bulb. Olfactory epithelium in rats and mice is divided into four zones (zones 1–4). A given odorant receptor is expressed by sensory neurons located within one zone. Individual olfactory sensory neurons express a single odorant receptor. Olfactory sensory neurons expressing a given odorant receptor are distributed widely in the epithelial zone and converge their axons onto a few topographically fixed glomeruli that are located within a corresponding zone of the olfactory bulb. Each glomerulus represents a single odorant receptor.
http://physrev.physiology.org/content/86/2/409 Based on the detailed MRR properties and the positions of glomeruli, we tentatively divide the cluster C into four subclusters: C-1, C-2, C-3, and C-4 (Fig. 5B). In addition to phenol family odorants, C-1 glomeruli respond to aliphatic alcohols with a relatively short carbon chain (4OH-6OH). C-2 glomeruli invariably respond to salicylaldehyde (Fig. 12B), a phenol derivative with a carbonyl group attached to the ortho-position. Glomeruli in subcluster C-3 respond relatively selectively to phenols and phenyl ethers. Glomeruli in subcluster C-4 respond also to short aliphatic ketones and aliphatic ethers.
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https://en.wikipedia.org/wiki/Quadrat
A quadrat is a plot used in ecology and geography to isolate a standard unit of area for study of the distribution of an item over a large area. While originally rectangular, modern quadrats can be rectangular, circular, irregular, etc.,.[1][2] The quadrat is suitable for sampling plants, slow-moving animals (such as millipedes and insects), and some aquatic organisms.
When an ecologist wants to know how many organisms there are in a particular habitat, it would not be feasible to count them all. Instead, he or she would be forced to count a smaller representative part of the population, called a sample. Sampling of plants or animals that do not move much (such as snails), can be done using a sampling square called a quadrat. A suitable size of a quadrat depends on the size of the organisms being sampled. For example, to count plants growing on a school field, one could use a quadrat with sides 0.5 or 1 meter in length.
It is important that sampling in an area is carried out at random, to avoid bias. For example, if you were sampling from a school field, but for convenience only placed quadrats next to a path, this might not give a sample that was representative of the whole field. It would be an unrepresentative, or biased, sample. One way one can sample randomly is to place the quadrats at coordinates on a numbered grid. Quadrats may also be used sampling oneself.
Long-term studies may require that the same quadrats be revisited months or even years after initial sampling. Methods of relocating the precise area of study vary widely in accuracy, and include measurement from nearby permanent markers, use of total station theodolites, consumer-grade GPS, and differential GPS.[3]
FOUR VOLUMES
https://en.wikipedia.org/wiki/The_Voyage_of_the_Beagle
The account was completed and published as a four volume set in May 1839 as the Narrative of the Surveying Voyages of His Majesty's Ships Adventure and Beagle.[3] Volume one covers the first voyage under Commander Phillip Parker King, volume two is FitzRoy's account of the second voyage. Darwin's Journal and Remarks, 1832—1835 forms the third volume, and the fourth volume is a lengthy appendix. FitzRoy's account includes Remarks with reference to the Deluge in which he recanted his earlier interest in the geological writings of Charles Lyell and his remarks to Darwin during the expedition that sedimentary features they saw "could never have been effected by a forty days' flood", asserting his renewed commitment to a literal reading of the Bible.[4] He had married on the ship's return, and his wife was very religious.[5]
https://en.wikipedia.org/wiki/Bacteria
FOUR GROUPS
The Gram stain, developed in 1884 by Hans Christian Gram, characterises bacteria based on the structural characteristics of their cell walls.[66] The thick layers of peptidoglycan in the "Gram-positive" cell wall stain purple, while the thin "Gram-negative" cell wall appears pink. By combining morphology and Gram-staining, most bacteria can be classified as belonging to one of four groups (Gram-positive cocci, Gram-positive bacilli, Gram-negative cocci and Gram-negative bacilli). Some organisms are best identified by stains other than the Gram stain, particularly mycobacteria or Nocardia, which show acid-fastness on Ziehl–Neelsen or similar stains.[146] Other organisms may need to be identified by their growth in special media, or by other techniques, such as serology.
FOUR REGIONS
https://en.wikipedia.org/wiki/Visual_cortex
Visual area V4 is one of the visual areas in the extrastriate visual cortex. In macaques, it is located anterior to V2 and posterior to posterior inferotemporal area (PIT). It comprises at least four regions (left and right V4d, left and right V4v), and some groups report that it contains rostral and caudal subdivisions as well. It is unknown what the human homologue of V4 is, and this issue is currently the subject of much scrutiny.[34]
FOUR GENE CLUSTERS
https://en.wikipedia.org/wiki/Gene_cluster
In the case where a gene cluster is duplicated, some genes may be lost. Loss of genes is dependent of the number of genes originating in the gene cluster. In the four gene model, the ProtoHox cluster contained four genes which resulted in two twin clusters: the Hox cluster and the ParaHox cluster.[7] As its name indicates, the two gene model gave rise to the Hox cluster and the ParaHox cluster as a result of the ProtoHox cluster which contained only two genes. The three gene model was originally proposed in conjunction with the four gene model;[8] however, rather than the Hox cluster and the ParaHox cluster resulting from a cluster containing three genes, the Hox cluster and ParaHox cluster were as a result of single gene tandem duplication, identical genes found adjacent on the same chromosome.[7] This was independent of duplication of the ancestral ProtoHox cluster.
This model has been generally accepted since the mid-1970s. It postulates that gene clusters were formed as a result of gene duplication and divergence.[2] These gene clusters include the Hox gene cluster, the human β-globin gene cluster, and four clustered human growth hormone (hGH)/chorionic somaomammotropin genes.[3]
Historically, four models have been proposed for the formation and persistence of gene clusters.
FOUR SUBFAMILIES ONE 16 GENERA
https://en.wikipedia.org/wiki/Thripidae
The Thripidae are thus ordered into four subfamilies:
Dendrothripinae Priesner, 1925 (16 genera)
Panchaetothripinae Bagnall, 1912 (38 genera)
Sericothripinae Karny, 1921 (11 genera)
Thripinae (227 genera)
https://en.wikipedia.org/wiki/Mechanoreceptor
There are four types of mechanoreceptors embedded in ligaments. As all these types of mechanoreceptors are myelinated, they can rapidly transmit sensory information regarding joint positions to the central nervous system.[10]
Type I: (small) Low threshold, slow adapting in both static and dynamic settings
Type II: (medium) Low threshold, rapidly adapting in dynamic settings
Type III: (large) High threshold, slowly adapting in dynamic settings
Type IV: (very small) High threshold pain receptors that communicate injury
Type II and Type III mechanoreceptors in particular are believed to be linked to one's sense of proprioception
https://en.wikipedia.org/wiki/Bodhidharma
Pointing directly to one's mind[edit]
One of the fundamental Chán texts attributed to Bodhidharma is a four-line stanza whose first two verses echo the Laṅkāvatāra Sūtra's disdain for words and whose second two verses stress the importance of the insight into reality achieved through "self-realization":
A special transmission outside the scriptures
Not founded upon words and letters;
By pointing directly to [one's] mind
It lets one see into [one's own true] nature and [thus] attain Buddhahood.[46]
The stanza, in fact, is not Bodhidharma's, but rather dates to the year 1108.[47]
Wall-gazing[edit]
Tanlin, in the preface to Two Entrances and Four Acts, and Daoxuan, in the Further Biographies of Eminent Monks, mention a practice of Bodhidharma's termed "wall-gazing" (壁觀 bìguān). Both Tanlin[note 8] and Daoxuan[web 4] associate this "wall-gazing" with "quieting [the] mind"[22] (Chinese: 安心; pinyin: ānxīn).
In the Two Entrances and Four Acts, traditionally attributed to Bodhidharma, the term "wall-gazing" is given as follows:
THERE ARE FOUR GERM LAYERS IN AN EMBRYO- THE FOURTH IS DIFFERENT- WHICH IS WHY OFTEN YOU HEAR PEOPLE SAY THERE ARE THREE GERM LAYERS BUT THERE IS A FOURTH
https://en.wikipedia.org/wiki/Germ_layer
Neural crest[edit]
Because of its great importance, the neural crest is sometimes considered a fourth germ layer.[8] It is, however, derived from the ectoderm.
Tetrachromacy is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cells in the eye. Organisms with tetrachromacy are called tetrachromats.
https://en.wikipedia.org/wiki/Tetrachromacy
In tetrachromatic organisms, the sensory color space is four-dimensional, meaning that to match the sensory effect of arbitrarily chosen spectra of light within their visible spectrum requires mixtures of at least four primary colors.
Tetrachromacy is demonstrated among several species of birds, fish, amphibians, reptiles, insects and some mammals.[2][3] It was the normal condition of most mammals in the past; a genetic change made the majority of species of this class eventually lose two of their four cones.[4][5]
THEY HAVE A FOUR DOMAIN ARCHITECTURE- I POSTED A LONG TIME AGO PICTURES OF IT WHERE THERE ARE FOUR DOMAINS- EACH DOMAIN HAS 6 PARTS BUT THERE ARE FOUR DOMAINS- THE FOUR IS DOMINANT
https://en.wikipedia.org/wiki/Voltage-dependent_calcium_channel
The α1 subunit pore (~190 kDa in molecular mass) is the primary subunit necessary for channel functioning in the HVGCC, and consists of the characteristic four homologous I–IV domains containing six transmembrane α-helices each. The α1 subunit forms the Ca2+ selective pore, which contains voltage-sensing machinery and the drug/toxin-binding sites. A total of ten α1 subunits that have been identified in humans:[1] α1 subunit contains 4 homologous domains (labeled I–IV), each containing 6 transmembrane helices (S1–S6). This arrangement is analogous to a homo-tetramer formed by single-domain subunits of voltage-gated potassium channels (that also each contain 6 TM helices). The 4-domain architecture (and several key regulatory sites, such as the EF hand and IQ domain at the C-terminus) is also shared by the voltage gated sodium channels, which are thought to be evolutionary related to VDCCs.[8] The transmembrane helices from the 4 domains line up to form the channel proper; S5 and S6 helices are thought to line the inner pore surface, while S1–4 helices have roles in gating and voltage sensing (S4 in particular).[9] VDCCs are subject to rapid inactivation, which is thought to consist of 2 components: voltage-dependent (VDI) and calcium-dependent (CDI).[10] These are distinguished by using either Ba2+ or Ca2+ as the charge carrier in the external recording solution (in vitro). The CDI component is attributed to the binding of the Ca2+-binding signaling protein calmodulin (CaM) to at least 1 site on the channel, as Ca2+-null CaM mutants abolish CDI in L-type channels. Not all channels exhibit the same regulatory properties and the specific details of these mechanisms are still largely unknown.
The γ1 subunit is known to be associated with skeletal muscle VGCC complexes, but the evidence is inconclusive regarding other subtypes of calcium channel. The γ1 subunit glycoprotein (33 kDa) is composed of four transmembrane spanning helices. The γ1 subunit does not affect trafficking, and, for the most part, is not required to regulate the channel complex. However, γ2, γ3, γ4 and γ8 are also associated with AMPA glutamate receptors.
The intracellular β subunit (55 kDa) is an intracellular MAGUK-like protein (Membrane-Associated Guanylate Kinase) containing a guanylate kinase (GK) domain and an SH3 (src homology 3) domain. The guanylate kinase domain of the β subunit binds to the α1 subunit I-II cytoplasmic loop and regulates HVGCC activity. There are four known genes for the β subunit:
CACNB1 (CACNB1),
CACNB2 (CACNB2),
CACNB3 (CACNB3),
CACNB4 (CACNB4).
IT DESCRIBES THAT USUALLY IT DOES NOT GO BEYOND QUADRUPLE BYPASS----IT SAYS IT IS VERY RARE TO GO PAST QUADRUPLE
https://en.wikipedia.org/wiki/Coronary_artery_bypass_surgery
https://en.wikipedia.org/wiki/File:Blausen_0152_CABG_All.png
The terms single bypass, double bypass, triple bypass, quadruple bypass and quintuple bypass refer to the number of coronary arteries bypassed in the procedure. In other words, a double bypass means two coronary arteries are bypassed (e.g., the left anterior descending (LAD) coronary artery and right coronary artery (RCA)); a triple bypass means three vessels are bypassed (e.g., LAD, RCA and left circumflex artery (LCX)); a quadruple bypass means four vessels are bypassed (e.g., LAD, RCA, LCX and first diagonal artery of the LAD) while quintuple means five. Left main coronary artery obstruction requires two bypasses, one to the LAD and one to the LCX. Bypass of more than four coronary arteries is uncommon.[citation needed]
THE FIRST TIGER STRIPE PATTERN HAD 64 STRIPES THAT IS FOUR TIMES 16 FOUR QUADRANT MODELS
https://en.wikipedia.org/wiki/Tigerstripe
It is unclear who developed the first tigerstripe pattern, consisting of sixty-four (64) stripes.
https://en.wikipedia.org/wiki/Four-lined_snake
Elaphe quatuorlineata (common names: four-lined snake, Bulgarian ratsnake[3]) is a member of the family Colubridae.[4] The four-lined snake is a non-venomous species and one of the largest in the Colubridae.[5]
IGG IS 75 PERCENT OF SERUM ANTIBODIES- THERE ARE FOUR TYPES OF IGG AND ALSO IT IS TETRAMERIC WITH FOUR PEPTIDE CHAINS (THERE ARE FIVE ANTIBODIES AND THEY FIT THE QUADRANT PATTERN THE FOURTH IS DIFFERENT AND PEOPLE DONT KNOW WHAT IT DOES THE FIFTH IS ULTRA TRANSCENDENT)
https://en.wikipedia.org/wiki/Immunoglobulin_G
IgG antibodies are large molecules of about 150[7][8] kDa made of four peptide chains. It contains two identical class γ heavy chains of about 50 kDa and two identical light chains of about 25 kDa, thus a tetrameric quaternary structure. The two heavy chains are linked to each other and to a light chain each by disulfide bonds. The resulting tetramer has two identical halves, which together form the Y-like shape. Each end of the fork contains an identical antigen binding site. The various regions and domains of a typical IgG are depicted in the figure to the left. The Fc regions of IgGs bear a highly conserved N-glycosylation site. The N-glycans attached to this site are predominantly core-fucosylated diantennary structures of the complex type. In addition, small amounts of these N-glycans also bear bisecting GlcNAc and α-2,6-linked sialic acid residues.[9]
The various regions and domains of a typical IgG
Subclasses[edit]
There are four IgG subclasses (IgG1, 2, 3, and 4) in humans, named in order of their abundance in serum (IgG1 being the most abundant).
There are four genera in the Scalpini:
https://en.wikipedia.org/wiki/Scalopini
Parascalops, the hairy-tailed mole of northeastern North America
Scalopus, the common and widely distributed eastern mole
Scapanus, three species of moles found west of the Rocky Mountains
Scapanulus, the Gansu mole of China
There are four genera in the Scalpini:
https://en.wikipedia.org/wiki/Scalopini
Parascalops, the hairy-tailed mole of northeastern North America
Scalopus, the common and widely distributed eastern mole
Scapanus, three species of moles found west of the Rocky Mountains
Scapanulus, the Gansu mole of China
FOUR GROUPS OF HEXAPODA
https://en.wikipedia.org/wiki/Insect
Traditional morphology-based or appearance-based systematics have usually given the Hexapoda the rank of superclass,[25]:180 and identified four groups within it: insects (Ectognatha), springtails (Collembola), Protura, and Diplura, the latter three being grouped together as the Entognatha on the basis of internalized mouth parts
FOUR GROUPS
https://en.wikipedia.org/wiki/Sharp-shinned_hawk
This species is widespread in North America, Central America, South America and the Greater Antilles. Below, the distributions of the four groups (see taxonomy) are described as they occur roughly from north to south:
The nominate (A. s. striatus) group is widespread in North America, occurring in all of the forested part of USA and Canada, breeding in most of it. Populations in the northern part of the range migrate south and spend the non-breeding season (winter) in the southern USA, Mexico and Central America as far south as Panama, with a smaller number spending the winter in the Greater Antilles. Resident populations exist in temperate parts of the USA, Canada (in a few coastal regions), Mexico (highlands from Sonora to Oaxaca), Cuba, Hispaniola and Puerto Rico.
A. (s.) chionogaster (white-breasted hawk) occurs in highlands from far southern Mexico (Chiapas and Oaxaca), through Honduras, Guatemala and El Salvador, to Nicaragua. It is, as far as known, resident, but some local movements may occur.
A. (s.) ventralis (plain-breasted hawk) occurs in the coastal mountains of northern Venezuela and Colombia, south through the Andes from western Venezuela, through Colombia, Ecuador and Peru, to central Bolivia. A disjunct population occurs in the Tepuis of southern Venezuela (likely to extend into adjacent parts of Roraima in far northern Brazil, but this remains unconfirmed). It is, as far as known, resident, but some local movements may occur.
A. (s.) erythronemius (rufous-thighed hawk) is widespread in eastern South America in eastern and southern Brazil, Uruguay, Paraguay, north-eastern Argentina and south-eastern Bolivia. It is, as far as known, resident in some regions and migratory in others. The movements are generally poorly understood, but it only occurs seasonally at some localities in Argentina.
Sharp-shinned hawk is sometimes separated into four species, with the northern group (see distribution) retaining both the scientific name and the common name: sharp-shinned hawk (A. striatus). In addition to the nominate taxon (A. s. striatus), it includes subspecies perobscurus, velox, suttoni, madrensis, fringilloides, and venator. The three remaining taxa, each considered a monotypic species if split, are the white-breasted hawk (A. chionogaster; Kaup, 1852), plain-breasted hawk (A. ventralis; Sclater, 1866) and rufous-thighed hawk (A. erythronemius; Kaup, 1850).
https://en.wikipedia.org/wiki/Spizaetus
FOUR SPECIES
New World species retained in Spizaetus
Black hawk-eagle or tyrant hawk-eagle, Spizaetus tyrannus
Black-and-white hawk-eagle, Spizaetus melanoleucus - traditionally Spizastur
Ornate hawk-eagle, Spizaetus ornatus
Black-and-chestnut eagle, Spizaetus isidori - traditionally Oroaetus
FOUR MAJOR DOPAMINERGIC PATHWAYS
there are four minor ones
https://en.wikipedia.org/wiki/Dopaminergic_pathways
Pathways [edit]
There are eight dopaminergic pathways. The four major ones are listed in the table below.
Pathway name Description Associated processes Associated disorders
Mesocorticolimbic
projection
Mesolimbic
pathway
The mesolimbic pathway transmits dopamine from the ventral tegmental area (VTA) to the nucleus accumbens. The VTA is located in the midbrain, and the nucleus accumbens is in the ventral striatum. The "meso" prefix in the word "mesolimbic" refers to the midbrain, or "middle brain", since "meso" means "middle" in Greek.
reward-related cognition
incentive salience ("wanting")
pleasure ("liking") response from certain stimuli
positive reinforcement
aversion-related cognition
ADHD
addiction
schizophrenia
Mesocortical
pathway
The mesocortical pathway transmits dopamine from the VTA to the prefrontal cortex. The "meso" prefix in "mesocortical" refers to the VTA, which is located in the midbrain, and "cortical" refers to the cortex.
executive functions
ADHD
addiction
schizophrenia
Nigrostriatal pathway
The nigrostriatal pathway transmits dopamine from the substantia nigra pars compacta (SNc) to the caudate nucleus and putamen. The substantia nigra is located in the midbrain, while both the caudate nucleus and putamen is located in the dorsal striatum.
motor function
reward-related cognition
associative learning
addiction
chorea
Parkinson's disease
Tuberoinfundibular pathway
The tuberoinfundibular pathway transmits dopamine from the hypothalamus (arcuate nucleus aka "infundibular nucleus") to the pituitary gland. This pathway influences the secretion of certain hormones, including prolactin. "Infundibular" in the word "tuberoinfundibular" refers to the cup or infundibulum, out of which the pituitary gland develops.
activity of this pathway inhibits the release of prolactin.
hyperprolactinaemia
http://www.answering-islam.org/Quran/Science/embryo.html
FOUR STAGES EMBRYO DEVELOPMENT QURAN AND GALEN
The account of the different stages in embryology as described by the Qur'an, ar-Razi and al-Quff is identical to that taught by Galen, writing in around AD 150 in Pergamum (Bergama in modern Turkey). Galen taught that the embryo developed in four stages as detailed below.
Galen: De Semine in Greek
English translation:
But let us take the account back again to the first conformation of the animal, and in order to make our account orderly and clear, let us divide the creation of the foetus overall into four periods of time. The first is that in which. as is seen both in abortions and in dissection, the form of the semen prevails (Arabic nutfah). At this time, Hippocrates too, the all-marvelous, does not yet call the conformation of the animal a foetus; as we heard just now in the case of semen voided in the sixth day, he still calls it semen. But when it has been filled with blood (Arabic alaqa), and heart, brain and liver are still unarticulated and unshaped yet have by now a certain solidarity and considerable size, this is the second period; the substance of the foetus has the form of flesh and no longer the form of semen. Accordingly you would find that Hippocrates too no longer calls such a form semen but, as was said, foetus. The third period follows on this, when, as was said, it is possible to see the three ruling parts clearly and a kind of outline, a silhouette, as it were, of all the other parts (Arabic mudghah). You will see the conformation of the three ruling parts more clearly, that of the parts of the stomach more dimly, and much more still, that of the limbs. Later on they form "twigs", as Hippocrates expressed it, indicating by the term their similarity to branches. The fourth and final period is at the stage when all the parts in the limbs have been differentiated; and at this part Hippocrates the marvelous no longer calls the foetus an embryo only, but already a child, too when he says that it jerks and moves as an animal now fully formed (Arabic ‘a new creation’) ...
... The time has come for nature to articulate the organs precisely and to bring all the parts to completion. Thus it caused flesh to grow on and around all the bones, and at the same time ... it made at the ends of the bones ligaments that bind them to each other, and along their entire length it placed around them on all sides thin membranes, called periosteal, on which it caused flesh to grow [19].
Qur'an: Sura 23:13-14 in Arabic for comparison
English translation:
Thereafter We made him (the offspring of Adam) as a Nutfah (mixed drops of the male and female sexual discharge and lodged it) in a safe lodging (womb of the woman). Then We made the Nutfah into a clot (Alaqa, a piece of thick coagulated blood), then We made the clot into a little lump of flesh (Mudghah), then We made out of that little lump of flesh bones, then We clothed the bones with flesh, and then We brought it forth as another creation. So blessed be Allah, the Best of Creators!
The first stage, geniture, corresponds to [nutfah], the drop of semen; the second stage, a bloody vascularised foetus with unshaped brain, liver and heart ("when it has been filled with blood") corresponds to [alaqa], the blood clot; the third stage "has the form of flesh" and corresponds to [mudghah], the morsel of chewed flesh. The fourth and final stage, puer, was when all the organs were well formed, joints were freely moveable, and the foetus began to move [20]. If the reader is in any doubt about the clear link being described here between the Galenic and the Qur'anic stages, it may be pointed out that it was early Muslim doctors, including Ibn-Qayyim, who first spotted the similarity. Basim Musallam, Director of the Centre of Middle Eastern Studies at the University of Cambridge concludes
"The stages of development which the Qur'an and Hadith established for believers agreed perfectly with Galen's scientific account ... There is no doubt that medieval thought appreciated this agreement between the Qur'an and Galen, for Arabic science employed the same Qur'anic terms to describe the Galenic stages" [21].
FOUR SUBDIVISIONS OF ECOLOGY
https://en.wikipedia.org/wiki/Population_ecology
The older term, autecology (from Greek: αὐτο, auto, "self"; οίκος, oikos, "household"; and λόγος, logos, "knowledge"), refers to roughly the same field of study as population ecology. It derives from the division of ecology into autecology—the study of individual species in relation to the environment—and synecology—the study of groups of organisms in relation to the environment—or community ecology. Odum (1959, p. 8) considered that synecology should be divided into population ecology, community ecology, and ecosystem ecology, defining autecology as essentially "species ecology."[1] However, for some time biologists have recognized that the more significant level of organization of a species is a population, because at this level the species gene pool is most coherent. In fact, Odum regarded "autecology" as no longer a "present tendency" in ecology (i.e., an archaic term), although included "species ecology"—studies emphasizing life history and behavior as adaptations to the environment of individual organisms or species—as one of four subdivisions of ecology.
The 4 “P’s” of Birth – The Need to Sync your Body, your Baby and Your Mind
JUNE 18, 2011 BY DEENA BLUMENFELD
When most of us hear about birth it’s in the singular, “When I was in labor…” or “The baby just didn’t budge.” or “They told me my pelvis was just too small.” or “I felt really strong and proud of giving birth naturally.” All of these things describe just one component of labor and birth. The reality is, that birth is a complex event and all four aspects need to come together to make this birth happen.
These 4 components to the birth process are: the passageway (pelvis), the passenger, the powers and the psyche. All of these must work together in synchronicity to achieve a successful, vaginal birth. Think of them as gears in a machine. If one of the gears is misaligned, then the whole machine malfunctions.
The Passageway (a.k.a The Pelvis):
I want to first talk about the pelvic inlet and the pelvic outlet. The pelvic inlet is the top opening of the pelvis. This is the part the baby’s head enters first. The pelvic outlet is where the baby’s head (and body!) exits mom. These dimensions need to be sized sufficiently to allow baby to maneuver comfortably through the pelvis for birth.
The tailbone (sacrum or coccyx) needs to be sufficiently mobile to be gently pressed back out of the way when baby moves through. Your sacroiliac joint allows this nutation or counter-nutation of the sacrum.
The symphisis pubis is a cartilaginous joint in the front of the pelvis. It also needs to be properly mobile to help the pelvis flex to allow baby to pass through. The relaxin hormone in your body helps both the tailbone and the symphisis pubis become more mobile to facilitate birth.
So, all of the physical components of the pelvis need to be working, moving, properly to facilitate birth.
The Passenger:
Yep. This would be the baby. Mom carries the baby, hence the term passenger. The baby needs to be positioned properly to make it through the pelvis. The optimal position for birth is Occiput Anterior (OA). However, babies can be born vaginally in a number of positions. To learn more about their positions in the womb (and how you can influence it) check out Spinning Babies.
What’s important to know here is that if baby is mal-positioned, she will have trouble fitting through the passageway, possibly necessitating a c-section.
The other things to note in regards to baby is their desire to be born and their sense of safety outside the womb. Our babies are strongly intuitive beings. They know when mom is fearful, or uncomfortable emotionally. This can have an impact on how baby will choose to be born. (see Psyche below for mom’s mental state)
The Powers:
These are your contractions and your additional efforts for pushing. Your contractions need to be strong enough to dilate the cervix and aid the baby in his decent. They need to be at regular intervals, moving closer together and increasing in strength throughout labor. On the flip side, they can’t be too strong, or too intense or you have a case of fetal distress and / or a mom who can’t cope with her contractions without medical interventions. If the contractions are too weak or not at regular enough intervals, your care provider might suggest using Pitocin (synthetic oxytocin) to amp them up.
The Psyche:
The Psyche is another word for you your emotional state during birth. If mom is afraid, tense, stressed out, angry, feels unsafe or unsupported, she will not likely do well during birth. For some, the fear is intense enough to schedule a c-section and to avoid a vaginal birth all together. For others, it may prevent cervical dilation, fetal decent, or prevent mom from pushing effectively. (Think Ina May’s “Sphincter Law”).
A good emotional state helps mom cope with the pain effectively; helps her tune in to her body; helps guide her to her baby’s needs and allows the other 3 P’s to sync up effectively. A mom who’s psyche is healthy, strong and who has good support during labor, will have a good birth. Regardless of the medical interventions she may need, she will ride her labor to a birth experience she will remember with a strong heart and a peaceful mind.
There is no one “P” that can work without the others. All four must be working properly for baby to join the world in the way they are intended. The “P’s” can be influenced by mom’s movements, position, her care provider, her support people, and medical intervention. Birth is a complicated, multifaceted, life-changing event. Get yourself in a good head-space and you will be able to work with issues that may arise with the Passageway, the Passenger and the Powers.
In fact, it’s much more commonplace to observe laminin in a swastika configuration than in a cross-like one.
The four-toed elephant shrew or four-toed sengi is the only living species in the genus Petrodromus, which together with three other extant genera Rhynchocyon, Macroscelides and Elephantulus constitutes the order Macroscelidea.[1] This species is only found in particular regions in Africa and is smaller in size compared to its relatives.[3] A comprehensive recording of this species is lacking.[1]
https://en.wikipedia.org/wiki/Four-toed_elephant_shrew
As its name suggests, the species has four toes on its hind feet,[4] and like other elephant shrews, it has been named for its elephant-like, mobile proboscis.[5]
https://en.wikipedia.org/wiki/Skin_flora
Staphylococcus epidermidis and Staphylococcus aureus were thought from cultural based research to be dominant. However 16S ribosomal RNA research finds that while common, these species make up only 5% of skin bacteria.[4] However, skin variety provides a rich and diverse habitat for bacteria. Most come from four phyla: Actinobacteria (51.8%), Firmicutes (24.4%), Proteobacteria (16.5%), and Bacteroidetes (6.3%).
https://en.wikipedia.org/wiki/Chemokine
FOUR CYSTEINE FAMILIES- FOUR GROUPS AND FOUR CYTESTEINES
Cytokine proteins are classified as chemokines according to behavior and structural characteristics. In addition to being known for mediating chemotaxis, chemokines are all approximately 8-10 kilodaltons in mass and have four cysteine residues in conserved locations that are key to forming their 3-dimensional shape.
FOUR SUBFAMILIES
Chemokines have been classified into four main subfamilies: CXC, CC, CX3C and XC. All of these proteins exert their biological effects by interacting with G protein-linked transmembrane receptors called chemokine receptors, that are selectively found on the surfaces of their target cells.[1]
T-lymphocytes: the four key chemokines that are involved in the recruitment of T lymphocytes to the site of inflammation are: CCL2, CCL1, CCL22 and CCL17.
Proteins are classified into the chemokine family based on their structural characteristics, not just their ability to attract cells. All chemokines are small, with a molecular mass of between 8 and 10 kDa. They are approximately 20-50% identical to each other; that is, they share gene sequence and amino acid sequence homology. They all also possess conserved amino acids that are important for creating their 3-dimensional or tertiary structure, such as (in most cases) four cysteines that interact with each other in pairs to create a Greek key shape that is a characteristic of chemokines. Intramolecular disulfide bonds typically join the first to third, and the second to fourth cysteine residues, numbered as they appear in the protein sequence of the chemokine. Typical chemokine proteins are produced as pro-peptides, beginning with a signal peptide of approximately 20 amino acids that gets cleaved from the active (mature) portion of the molecule during the process of its secretion from the cell. The first two cysteines, in a chemokine, are situated close together near the N-terminal end of the mature protein, with the third cysteine residing in the centre of the molecule and the fourth close to the C-terminal end. A loop of approximately ten amino acids follows the first two cysteines and is known as the N-loop. This is followed by a single-turn helix, called a 310-helix, three β-strands and a C-terminal α-helix. These helices and strands are connected by turns called 30s, 40s and 50s loops; the third and fourth cysteines are located in the 30s and 50s loops.[6]
Types by structure[edit]
The four chemokine subfamilies
CC chemokines
Name Gene Other name(s) Receptor Uniprot
CCL1 Scya1 I-309, TCA-3 CCR8
CCL2 Scya2 MCP-1 CCR2 P13500
CCL3 Scya3 MIP-1a CCR1 P10147
CCL4 Scya4 MIP-1β CCR1, CCR5 P13236
CCL5 Scya5 RANTES CCR5 P13501
CCL6 Scya6 C10, MRP-2 CCR1 P27784
CCL7 Scya7 MARC, MCP-3 CCR2 P80098
CCL8 Scya8 MCP-2 CCR1, CCR2B, CCR5 P80075
CCL9/CCL10 Scya9 MRP-2, CCF18, MIP-1? CCR1 P51670
CCL11 Scya11 Eotaxin CCR2, CCR3, CCR5 P51671
CCL12 Scya12 MCP-5 Q62401
CCL13 Scya13 MCP-4, NCC-1, Ckβ10 CCR2, CCR3, CCR5 Q99616
CCL14 Scya14 HCC-1, MCIF, Ckβ1, NCC-2, CCL CCR1 Q16627
CCL15 Scya15 Leukotactin-1, MIP-5, HCC-2, NCC-3 CCR1, CCR3 Q16663
CCL16 Scya16 LEC, NCC-4, LMC, Ckβ12 CCR1, CCR2, CCR5, CCR8 O15467
CCL17 Scya17 TARC, dendrokine, ABCD-2 CCR4 Q92583
CCL18 Scya18 PARC, DC-CK1, AMAC-1, Ckβ7, MIP-4 P55774
CCL19 Scya19 ELC, Exodus-3, Ckβ11 CCR7 Q99731
CCL20 Scya20 LARC, Exodus-1, Ckβ4 CCR6 P78556
CCL21 Scya21 SLC, 6Ckine, Exodus-2, Ckβ9, TCA-4 CCR7 O00585
CCL22 Scya22 MDC, DC/β-CK CCR4 O00626
CCL23 Scya23 MPIF-1, Ckβ8, MIP-3, MPIF-1 CCR1 P55773
CCL24 Scya24 Eotaxin-2, MPIF-2, Ckβ6 CCR3 O00175
CCL25 Scya25 TECK, Ckβ15 CCR9 O15444
CCL26 Scya26 Eotaxin-3, MIP-4a, IMAC, TSC-1 CCR3 Q9Y258
CCL27 Scya27 CTACK, ILC, Eskine, PESKY, skinkine CCR10 Q9Y4X3
CCL28 Scya28 MEC CCR3, CCR10 Q9NRJ3
CXC chemokines
Name Gene Other name(s) Receptor Uniprot
CXCL1 Scyb1 Gro-a, GRO1, NAP-3, KC CXCR2 P09341
CXCL2 Scyb2 Gro-β, GRO2, MIP-2a CXCR2 P19875
CXCL3 Scyb3 Gro-?, GRO3, MIP-2β CXCR2 P19876
CXCL4 Scyb4 PF-4 CXCR3B P02776
CXCL5 Scyb5 ENA-78 CXCR2 P42830
CXCL6 Scyb6 GCP-2 CXCR1, CXCR2 P80162
CXCL7 Scyb7 NAP-2, CTAPIII, β-Ta, PEP P02775
CXCL8 Scyb8 IL-8, NAP-1, MDNCF, GCP-1 CXCR1, CXCR2 P10145
CXCL9 Scyb9 MIG, CRG-10 CXCR3 Q07325
CXCL10 Scyb10 IP-10, CRG-2 CXCR3 P02778
CXCL11 Scyb11 I-TAC, β-R1, IP-9 CXCR3, CXCR7 O14625
CXCL12 Scyb12 SDF-1, PBSF CXCR4, CXCR7 P48061
CXCL13 Scyb13 BCA-1, BLC CXCR5 O43927
CXCL14 Scyb14 BRAK, bolekine O95715
CXCL15 Scyb15 Lungkine, WECHE Q9WVL7
CXCL16 Scyb16 SRPSOX CXCR6 Q9H2A7
CXCL17 VCC-1 DMC, VCC-1 Q6UXB2
C chemokines
Name Gene Other name(s) Receptor Uniprot
XCL1 Scyc1 Lymphotactin a, SCM-1a, ATAC XCR1 P47992
XCL2 Scyc2 Lymphotactin β, SCM-1β XCR1 Q9UBD3
CX3C chemokines
Name Gene Other name(s) Receptor Uniprot
CX3CL1 Scyd1 Fractalkine, Neurotactin, ABCD-3 CX3CR1 P78423
Members of the chemokine family are divided into four groups depending on the spacing of their first two cysteine residues. Thus the nomenclature for chemokines is, e.g.: CCL1 for the ligand 1 of the CC-family of chemokines, and CCR1 for its respective receptor.
CC chemokines[edit]
The CC chemokine (or β-chemokine) proteins have two adjacent cysteines (amino acids), near their amino terminus. There have been at least 27 distinct members of this subgroup reported for mammals, called CC chemokine ligands (CCL)-1 to -28; CCL10 is the same as CCL9. Chemokines of this subfamily usually contain four cysteines (C4-CC chemokines), but a small number of CC chemokines possess six cysteines (C6-CC chemokines). C6-CC chemokines include CCL1, CCL15, CCL21, CCL23 and CCL28.[7] CC chemokines induce the migration of monocytes and other cell types such as NK cells and dendritic cells.
Examples of CC chemokine include monocyte chemoattractant protein-1 (MCP-1 or CCL2) which induces monocytes to leave the bloodstream and enter the surrounding tissue to become tissue macrophages.
CCL5 (or RANTES) attracts cells such as T cells, eosinophils and basophils that express the receptor CCR5.
Increased CCL11 levels in blood plasma are associated with aging (and reduced neurogenesis) in mice and humans.[8]
CXC chemokines[edit]
The two N-terminal cysteines of CXC chemokines (or α-chemokines) are separated by one amino acid, represented in this name with an "X". There have been 17 different CXC chemokines described in mammals, that are subdivided into two categories, those with a specific amino acid sequence (or motif) of glutamic acid-leucine-arginine (or ELR for short) immediately before the first cysteine of the CXC motif (ELR-positive), and those without an ELR motif (ELR-negative). ELR-positive CXC chemokines specifically induce the migration of neutrophils, and interact with chemokine receptors CXCR1 and CXCR2. An example of an ELR-positive CXC chemokine is interleukin-8 (IL-8), which induces neutrophils to leave the bloodstream and enter into the surrounding tissue. Other CXC chemokines that lack the ELR motif, such as CXCL13, tend to be chemoattractant for lymphocytes. CXC chemokines bind to CXC chemokine receptors, of which seven have been discovered to date, designated CXCR1-7.
C chemokines[edit]
The third group of chemokines is known as the C chemokines (or γ chemokines), and is unlike all other chemokines in that it has only two cysteines; one N-terminal cysteine and one cysteine downstream. Two chemokines have been described for this subgroup and are called XCL1 (lymphotactin-α) and XCL2 (lymphotactin-β).
CX3C chemokines[edit]
A fourth group has also been discovered and members have three amino acids between the two cysteines and is termed CX3C chemokine (or d-chemokines). The only CX3C chemokine discovered to date is called fractalkine (or CX3CL1). It is both secreted and tethered to the surface of the cell that expresses it, thereby serving as both a chemoattractant and as an adhesion molecule.
FOUR SUBSPECIES
https://en.wikipedia.org/wiki/Common_gull
The common gull (Larus canus) is a medium-sized gull which breeds in northern Asia, northern Europe and northwestern North America.
There are four subspecies, two of which are considered distinct species by some authorities:[3][5]
L. c. canus – Linnaeus, 1758 – common gull. nominate, found in Europe and western Asia. Small; mantle medium grey (palest subspecies); wingtips with extensive black; iris dark. Wingspan 110–125 cm (43–49 in); mass 290–480 g (10–17 oz).
L. c. heinei – Homeyer, 1853 – Russian common gull. Found in central northern Asia. Medium size; mantle dark grey (darkest subspecies); wingtips with extensive black; iris dark. Mass 315–550 g (11.1–19.4 oz).
L. c. kamtschatschensis – Bonaparte, 1857; syn. L. kamtschatschensis – Kamchatka gull. Found in northeastern Asia. Large; mantle medium-dark grey; wingtips with extensive black; iris pale. Mass 394–586 g (13.9–20.7 oz).
L. c. brachyrhynchus – Richardson, 1831; syn. L. brachyrhynchus – mew gull or short-billed gull. Found in Alaska and western Canada. Small; mantle medium-dark grey; wingtips with little black and much white; iris pale. Wingspan 96–102 cm (38–40 in); mass 320–550 g (11–19 oz).
FOUR
https://en.wikipedia.org/wiki/Foodborne_illness
Trichothecenes – sourced from Cephalosporium, Fusarium, Myrothecium, Stachybotrys and Trichoderma. The toxins are usually found in molded maize, wheat, corn, peanuts and rice, or animal feed of hay and straw.[35][36] Four trichothecenes, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and deoxynivalenol (DON) have been most commonly encountered by humans and animals. The consequences of oral intake of, or dermal exposure to, the toxins will result in Alimentary toxic aleukia, neutropenia, aplastic anemia, thrombocytopenia and/or skin irritation.[37][38][39] In 1993, the FDA issued a document for the content limits of DON in food and animal feed at an advisory level.[40] In 2003, US published a patent that is very promising for farmers to produce a trichothecene-resistant crop.[41]
https://patient.info/health/knee-ligament-injuries-leaflet
THE FOUR LIGAMENTS OF THE KNEE
The ligaments in the knee connect the femur (thighbone) to the tibia (shin bone), and include the following:
Anterior cruciate ligament (ACL). ...
Posterior cruciate ligament (PCL). ...
Medial collateral ligament (MCL). ...
Lateral collateral ligament (LCL).
https://en.wikipedia.org/wiki/Colombian_four-eyed_frog
The Colombian four-eyed frog (Pleurodema brachyops; in Spanish: sapito lipon) is a species of frog in the Leptodactylidae family. It is found in an area stretching from Guyana and northern Brazil (Roraima state) through Venezuela (including Isla Margarita) and Colombia into Panama as well as the Netherlands Antilles.[2]
The common name "four-eyed frog" refers to two inguinal poison glands that resemble eyes.[3] When threatened, the frog lowers its head and raises its rear. When the frog adopts this posture the poison glands are also raised toward the predator. The predator may also confuse the frog's raised posterior for the head of a larger animal.[4]
https://en.wikipedia.org/wiki/Agonopterix_robiniella
Agonopterix robiniella, the four-dotted agonopterix moth or locust leaf roller, is a moth of the family Depressariidae. It is found in North America, where it has been recorded from Nova Scotia to Georgia, west to Oklahoma, north to Illinois, Michigan and southern Ontario.[1]
https://en.wikipedia.org/wiki/Agonopterix_robiniella
Agonopterix robiniella, the four-dotted agonopterix moth or locust leaf roller, is a moth of the family Depressariidae. It is found in North America, where it has been recorded from Nova Scotia to Georgia, west to Oklahoma, north to Illinois, Michigan and southern Ontario.[1]
Four stages[change | change source]
https://simple.wikipedia.org/wiki/Translation_(genetics)
Overview of the translation of eukaryotic messenger RNA
Translation happens in four stages: activation (make ready), initiation (start), elongation (make longer) and termination (stop). These terms describe the growth of the amino acid chain (polypeptide).
Amino acids are brought to ribosomes and assembled into proteins. In the activation stage, the correct amino acid is covalently bonded to the correct transfer RNA (tRNA). When the tRNA is connected to an amino acid, it is "charged".
Initiation is when the small part of the ribosome connects to 5' end of the mRNA with the help of initiation factors (IF).
Elongation is when the amino acids brought by the "charged" tRNAs are connected to each other to form a polypeptide.
Termination of the polypeptide happens when site A of the ribosome meets a stop codon (UAA, UAG, or UGA). There is no tRNA that matches that codon, so no tRNA can connect to it. This breaks the polypeptide off the ribosome.
I LISTENED TO TEACHING COMPANY COURSE ON BLACK HOLE PHYSICS IT WAS ALL QUADRANTS PENROSE DIAGRAMS
Merk Diezle shared a link.
Aug 29, 2016 5:39pm
https://en.wikipedia.org/wiki/File:PENROSE2.PNG
Penrose diagram - Wikipedia, the free encyclopedia
en.wikipedia.org
https://en.wikipedia.org/wiki/Penrose_diagram
Penrose diagrams the basis of black hole studies are quadrants as well as kruskal szekeres diagrams are also quadrants with four aspects
https://en.wikipedia.org/wiki/Fallopian_tube
https://simple.wikipedia.org/wiki/Fallopian_tube
FOUR PARTS FALLOPIAN TUBE
Parts[change | change source]
There are four parts of the fallopian tube from the ovary to the uterus:[1]
The fimbria
Infundibulum
Ampulla - where the ovum is fertilized
Isthmus
A cross section of Fallopian tube shows four distinct layers: serosa, subserosa, lamina propria and innermost mucosal layer.
Fleas are small flightless insects that form the order Siphonaptera
https://en.wikipedia.org/wiki/Flea
The order is divided into four infraorders and eighteen families.
https://en.wikipedia.org/wiki/Origin_of_the_domestic_dog
Phylogenetic analysis shows that modern dog mDNA haplotypes resolve into four monophyletic clades with strong statistical support, and these have been designated by researchers as clades A-D.
https://en.wikipedia.org/wiki/Apterygota
The composition and classification of Apterygota changed over time. By the mid-20th century, the subclass included four orders (Collembola, Protura, Diplura, and Thysanura).
https://en.wikipedia.org/wiki/Apidae
The old family Apidae contained four tribes (Apinae: Apini, Euglossini and Bombinae: Bombini, Meliponini) which have been reclassified as tribes of the subfamily Apinae, along with all of the former tribes of Anthophoridae (subfamily Athophorinae) and the former family Ctenoplectridae, which was demoted to tribe status. The trend to move groups down in taxonomic rank has been taken further by a 2005 Brazilian classification that places all existing bee families together under the name "Apidae",[5] but it has not been widely accepted in the literature since that time.
Many chelicerates have four pairs of walking legs. These include scorpions and spiders.
https://en.wikipedia.org/wiki/Catfish
I described that dragonflies are known for their flight by biologists and studied for their amazing flight capacities and that their flight reflects the quadrant model pattern. The mantis shrimp is studied by biologists for its sight, which reflects the quadrant model pattern. Ruminants like giraffes and cows are known for having to digest cellulose which other animals cannot do so they have four stomachs, reflecting the quadrant pattern.
The catfish is studied by biologists for its incredible capacity of perception called chemical perception. Catfish are known for their amazing ability to eat in muddy water where it cannot see. The way that it detects food is through its four pairs of barbels.
Catfish also have a maxilla reduced to a support for barbels; this means that they are unable to protrude their mouths as other fish such as carp.
Catfish may have up to four pairs of barbels: nasal, maxillary (on each side of mouth), and two pairs of chin barbels, even though pairs of barbels may be absent depending on the species. Catfish barbels always come as pairs. Many larger catfish also have chemoreceptors across their entire bodies, which means they "taste" anything they touch and "smell" any chemicals in the water. "In catfish, gustation plays a primary role in the orientation and location of food". Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are generally small. Like other ostariophysans, they are characterized by the presence of a Weberian apparatus. Their well-developed Weberian apparatus and reduced gas bladder allow for improved hearing as well as sound production.
Catfish are known for their capacity to eat and survive in muddy waters. The four pairs of barbels are what makes it possible for a catfish to live.
The channel catfish is an example of a catfish with four pairs of barbels.
https://en.wikipedia.org/wiki/Ciliate
Ciliates reproduce asexually, by various kinds of fission. An example of a ciliate is paramecium. During fission, the micronucleus undergoes mitosis and the macronucleus elongates and splits in half (except among the Karyorelictean ciliates, whose macronuclei do not divide). The cell then divides in two, and each new cell obtains a copy of the micronucleus and the macronucleus.
The process of conjugation reflects the quadrant model pattern.
During conjugation, two cells form a bridge between their cytoplasms, the micronuclei undergo meiosis, the macronuclei disappear, and the haploid micronuclei are exchanged over the bridge. In some ciliates (such as Vorticella), conjugating cells become permanently fused, and one conjugant is absorbed by the other. In most ciliate groups, however, the cells separate after conjugation, and both form new macronuclei from their micronuclei. Conjugation and autogamy are always followed by fission.
In general the process is as follows:
Compatible mating strains meet and partly fuse.
The micronuclei undergo meiosis producing four micronuclei per cell.
Three of these micronuclei disintegrate. The fourth undergoes mitosis. Notice how this is the quadrant pattern. Three disintegrate, the fourth which is different undergoes mitosis.
The two cells exchange a micronucleus.
The cells then separate.
The micronuclei in each cell fuse.
This is followed by mitosis which occurs three times giving rise to eight micronuclei.
Four of the new micronuclei transform into macronuclei
Finally binary fission occurs twice yielding four daughter cells.
At the end four daughter cells are produced
16 is the squares of the quadrant model- four rows of four 16- the mantis shrimp has the most complex vision of any creature and has four rows of four photoreceptors- the fourth row is different.
The mantis shrimp, or stomatopod, is used in biology as an example of an organism with an extraordinary visual mechanism. They are upheld by biologists as the organism that sees the world in an incredible way and of an organism that has developed a completely different mechanism of seeing than that of humans. But the seeing mechanism of the mantis shrimp fits the quadrant model pattern.
Compared to the three types of color receptive cones that humans possess (and one rod) in their eyes, the eyes of a mantis shrimp carry 16 types of color receptive cones. It was once thought that this gives the crustacean the ability to recognize colors that are unimaginable by other species.
The midband region of its eye is made up of six rows of specialised ommatidia. Four rows carry up to 16 different photoreceptor pigments, 12 for colour sensitivity, others for colour filtering. The vision of the mantis shrimp can perceive both polarised light and multispectral images. Their eyes (mounted on mobile stalks and capable of moving independently of each other) are similarly variably colored and are considered to be the most complex eyes in the animal kingdom
Rows 1–4 of the midband are specialised for color vision, from ultra-violet to longer wavelengths. Their UV-vision can detect five different frequency bands in the deep ultraviolet. To do this they use two photoreceptors in combination with four different colour filters.[
It has four rows with 16 different photoreceptors. The four is the quadrant. 16 is the number of squares in the quadrant model. 12 of the squares are for color sensitivity. That is the first three quadrants. The fourth quadrant is always different. The fourth quadrant has four photoreceptors for colour filtering. Therefore the mantis shrimp, the creature that biologists see as having the most special and unique visual mechanism, has a visual mechanism that fulfills the quadrant model pattern.
Some species have at least 16 different photoreceptor types, which are divided into four classes (their spectral sensitivity is further tuned by colour filters in the retinas), 12 of them for colour analysis in the different wavelengths (including six which are sensitive to ultraviolet light) and four of them for analysing polarised light. By comparison, most humans have only four visual pigments, of which three are dedicated to see colour, and the human lenses block ultraviolet light. The visual information leaving the retina seems to be processed into numerous parallel data streams leading into the central nervous system, greatly reducing the analytical requirements at higher levels.
The species Gonodactylus smithii is the only organism known to simultaneously detect the four linear and two circular polarization components required to measure all four Stokes parameters, which yield a full description of polarization. It is thus believed to have optimal polarization vision.
The vision of the stomatopod is the quadrant model pattern, and for biologists, that is what the creature is special for and what it is studied for.
From the top it looks like a quadrant
https://en.wikipedia.org/wiki/File:Haeckel_Cubomedusae.jpg
https://en.wikipedia.org/wiki/Box_jellyfish
The medusa form of a box jellyfish has a squarish, box-like bell. From each of the four lower corners of this hangs a short pedalium or stalk which bears one or more long, slender, hollow tentacles.The interior of the bell is known as the gastrovascular cavity. It is divided by four equidistant septa into a central stomach and four gastric pockets.
https://en.wikipedia.org/wiki/Chiropsalmus_quadrumanus
16 squares quadrant model
Chiropsalmus quadrumanus, commonly known as the four-handed box jellyfish, is a species of box jellyfish in class Cubozoa. It is found in the west Atlantic Ocean, the Gulf of Mexico and the Pacific Ocean. The sting is venomous and dangerous to humans, especially children.
Chiropsalmus quadrumanus is a cube-shaped, colourless, transparent jellyfish with a diameter of about 14 centimetres (5.5 in) and height a little less than this. The body is composed of a gelatinous material and the top edges are rounded while the top surface is flat. Bundles of 7 to 9 tentacles dangle from pedalia, palmate appendages at the four lower corners of the bell, with a tentacle on each "finger". The outer two tentacles are pinkish and the inner ones yellowish white and they can be up to 3 to 4 metres (9.8 to 13.1 ft) long. Halfway up the inside of the bell is the velarium, a horizontal ring of tissue partially blocking the aperture. The manubrium is a central column hanging down inside the bell with the mouth at its tip. The rounded stomach has four pouches connecting to radial sinuses along the edges of the bell. The gonads are on either side of the radial canals.[2]
The long tentacles of Chiropsalmus quadrumanus are armed with nematocysts, the purpose of which is to capture prey such as small fish and to deter predators. They can inflict an extremely painful sting on people that encounter them. There is a documented case of a four-year-old boy in the Gulf of Mexico dying within forty minutes of being stung.[5][6] Of forty nine people stung by jellyfish off the coast of Brazil over a five-year period, twenty were by identifiable species. Sixteen of these were identified as being caused by Chiropsalmus quadrumanus and four by the Portuguese man o' war (Physalia physalis). All these stings were linear in nature, causing both intense pain and systemic symptoms.[7] Apart from pain, the symptoms include cardiac dysfunction and respiratory depression. The rash lasts for several months. Antivenom administered within a few hours relieves the pain somewhat, reduces the severity of the rash, and improves other symptoms. In extreme cases, cardiopulmonary resuscitation can be effective if started promptly.[8]
It looks like a quadrants
https://en.wikipedia.org/wiki/File:Aurelia_aurita_2.jpg
https://en.wikipedia.org/wiki/Aurelia_aurita
Aurelia aurita (also called the moon jelly, moon jellyfish, common jellyfish, or saucer jelly) is a widely studied species of the genus Aurelia. All species in the genus are closely related, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus.
The jellyfish is translucent, usually about 25–40 cm (10–16 in) in diameter, and can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell. It feeds by collecting medusae, plankton, and mollusks with its tentacles, and bringing them into its body for digestion. It is capable of only limited motion, and drifts with the current, even when swimming.
It has four bright gonads that are under the stomach
https://en.wikipedia.org/wiki/Chloroplast
These chloroplasts, which can be traced back directly to a cyanobacterial ancestor, are known as primary plastids[26] ("plastid" in this context means almost the same thing as chloroplast[9]). All primary chloroplasts belong to one of four chloroplast lineages—the glaucophyte chloroplast lineage, the amoeboid Paulinella chromatophora lineage, the rhodophyte (red algal) chloroplast lineage, or the chloroplastidan (green) chloroplast lineage.[27] The rhodophyte and chloroplastidan lineages are the largest,[16] with chloroplastidan (green) being the one that contains the land plants.[16]
Chloroplast lineages
A primary endosymbiosis
event gave rise to four main
lineages of chloroplasts in
the glaucophytes, Paulinella, chlorophyta,
and rhodophyta.[27]
Some of these algae were
subsequently engulfed by
other algae, becoming
secondary (or tertiary)
endosymbionts.[14][16]
https://en.wikipedia.org/w…/File:Nucleomorph_chloroplast.svg
https://en.wikipedia.org/wiki/Chloroplast
Diagram of a four membraned chloroplast containing a nucleomorph.
I ORGINALLY GOT THIS FROM WIKIPEDIA
http://www.life.umd.edu/classroom/bsci424/BSCI223WebSiteFiles/Flagella.htm
The four types of arrangement for flagellum are
square 1: peritrichous
square 2: lophotrichous
sqaure 3: Amphitrichous
square 4: monotrichous
https://www.cliffsnotes.com/study-guides/biology/plant-biology/roots/root-zones
Four areas of the young root traditionally are recognized, but except for the terminal area, are not distinctly separate. Their descriptive names are only partially correct in describing the activities taking place in each area. These regions, starting at the tip and moving upwards towards the stem, are the root cap, zone of active cell division, zone of cell elongation, and zone of maturation.
The first two are compacted in the first centimeter or less of the axis with the latter two no more than 4–5 centimeters from the tip. Only the root cap and the cell division regions actually move through the soil. After cells start to elongate and mature, no further extension takes place, and the root is stationary for the rest of its life.
Root cap
The root cap is a cup-shaped, loosely cemented mass of parenchyma cells that covers the tip of the root. As cells are lost among the soil particles, new ones are added from the meristem behind the cap. The cap is a unique feature of roots; the tip of the stem has no such structure. From its shape, structure, and location, its primary function seems clear: It protects the cells under it from abrasion and assists the root in penetrating the soil. Phenomenal numbers of cap cells are produced to replace those worn off and lost as root tips push through the soil.
The movement is assisted by a slimy substance, mucigel, which is produced by cells of the root cap and epidermis. The mucigel
Lubricates the roots.
Contains materials that are inhibitory to roots of other species.
Influences ion uptake.
Attracts beneficial soil microorganisms.
Glues soil particles to the roots thereby improving the soil-plant contact and facilitating water movement from the soil into the plant.
Protects the root cells from drying out.
Root cap cells sense light in some as yet unexplained way and direct root growth away from light. The root cap also senses gravity to which roots respond by growing downward, bringing them into contact with the soil, the reservoir of nutrients and water used by plants. The root cap also responds to pressures exerted by the soil particles.
Zone of cell division
An apical meristem lies under and behind the root cap and, like the stem apical meristem, it produces the cells that give rise to the primary body of the plant. Unlike the stem meristem, it is not at the very tip of the root; it lies behind the root cap. Between the area of active division and the cap is an area where cells divide more slowly, the quiescent center. Most cell divisions occur along the edges of this center and give rise to columns of cells arranged parallel to the root axis. The parenchyma cells of the meristem are small, cuboidal, with dense protoplasts devoid of vacuoles and with relatively large nuclei.
The apical meristem of the root organizes to form the three primary meristems:protoderm, which gives rise to the epidermis; procambium, which produces xylem and phloem; and the ground meri-stem, which produces the cortex. Pith, present in most stems and produced from the ground meristem, is absent in most dicot (eudicot) roots, but is found in many monocot roots.
Zone of cell elongation
The cells in this zone stretch and lengthen as small vacuoles within the cytoplasm coalesce and fill with water. One or two large vacuoles occupy almost all of the cell volume in fully elongated cells. Cellular expansion in this zone is responsible for pushing the root cap and apical tip forward through the soil.
Zone of maturation
The elongating cells complete their differentiation into the tissues of the primary body in this zone. It is easily recognized because of the numerous root hairs that extend into the soil as outgrowths of single epidermal cells. They greatly increase the absorptive surface of roots during the growth period when large amounts of water and nutrients are needed. An individual root hair lives for only a day or two, but new ones form constantly nearer the tip as old ones die in the upper part of the zone.
The types of teeth fit the quadrant model pattern. Interestingly there are 16 teeth on the
top and bottom like the 16 squares of the quadrant model. The types of teeth are
*Square one: Incisors-- the first square is always the weakest
*Square two: Canines
*Square three: Premolars--the third square is always the most physical and solid. The premolars are large and grind food.
*Square four: Molars--the molars are the fourth and very different. The forth is always different.
FOUR TYPES OF TISSUE
https://en.wikipedia.org/wiki/Tissue_(biology)
Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.
https://en.wikipedia.org/wiki/Signs_and_symptoms_of_Parkinson%27s_disease
FOUR SYMPTOMS PARKINSONS
Four motor symptoms are considered cardinal in PD: slowness of movement (bradykinesia), tremor, rigidity and postural instability.[1] Typical for PD is an initial asymmetric distribution of these symptoms, where in the course of the disease a gradual progression to bilateral symptoms develop although some asymmetry usually persists. Other motor symptoms include gait and posture disturbances such as decreased arm swing, a forward-flexed posture and the use of small steps when walking; speech and swallowing disturbances; and other symptoms such as a mask-like face expression or small handwriting are examples of the range of common motor problems that can appear.[1]
Cardinal symptoms[edit]
Four symptoms are considered cardinal in PD: bradykinesia, tremor, rigidity and postural instability also referred to as parkinsonism.[1]
Tremor is the most apparent and well-known symptom.[1] It is also the most common; though around 30% of individuals with PD do not have tremor at disease onset, most develop it as the disease progresses.[1] It is usually a rest tremor: maximal when the limb is at rest and disappearing with voluntary movement and sleep.[1] It affects to a greater extent the most distal part of the limb, and at onset typically appears in only a single arm or leg, becoming bilateral later during the course of the disease.[1] Frequency of PD tremor is between 4 and 6 hertz (cycles per second). It is a pronation-supination tremor that is described as "pill-rolling," that is the index finger of the hand tends to get into contact with the thumb and perform a circular movement together.[1][2] Such term was given due to the similarity of the movement in PD patients with the former pharmaceutical technique of manually making pills.[2] PD tremor is not improved with alcohol intake, as opposed to essential tremor.[1]
Rigidity is a characterized by an increased muscle tone (an excessive and continuous contraction of the muscles) which produces stiffness and resistance to movement in joints.[1] Rigidity may be associated with joint pain; such pain being a frequent initial manifestation of the disease.[1] When limbs of the person with PD are passively moved by others a "cogwheel rigidity" is commonly seen.[1] Cogwheel-like or ratchety jerks are characterized by the articulation moving as opposed to the normal fluid movement; when a muscle is externally tried to move it resists at first but with enough force it is partially moved until it resists again and only with further force it will be moved.[1][3][4] The combination of tremor and increased tone is considered to be at the origin of cogwheel rigidity.[5]
Bradykinesia and akinesia: the former is slowness of movement while the latter is the absence of it.[1] It is the most characteristic clinical feature of PD, and is associated with difficulties along the whole course of the movement process, from planning to initiation and finally execution of a movement.[1] The performance of sequential and simultaneous movements is also hindered.[1] Bradykinesia is the most disabling symptom in the early stages of the disease.[3] Initial manifestations of bradykinesia are problems when performing daily life tasks requiring fine motor control such as writing, sewing or getting dressed.[1] Clinical evaluation is based in similar tasks consisting such as alternating movements between both hands or feet.[3] Bradykinesia is not equal for all movements or times. It is modified by the activity or emotional state of the subject to the point of some patients barely able to walk being capable of riding a bicycle.[1] Generally patients have less difficulties when some sort of external cue is provided.[1][6]
... immobile patients who become excited may be able to make quick movements such as catching a ball (or may be able to suddenly run if someone screams "fire"). This phenomenon (kinesia paradoxica) suggests that patients with PD have intact motor programmes but have difficulties accessing them without an external trigger, such as a loud noise, marching music or a visual cue requiring them to step over an obstacle.[1]
Postural instability: In the late stages postural instability is typical, which leads to impaired balance and frequent falls, and secondarily to bone fractures.[1] Instability is often absent in the initial stages, especially in younger people.[3] Up to 40% of the patients may experience falls and around 10% may have falls weekly, with number of falls being related to the severity of PD. It is produced by a failure of postural reflexes, along other disease related factors such as orthostatic hypotension or cognitive and sensory changes[1]
TETRAD IS FOUR
http://www.plantphysiol.org/content/124/1/7.full
Tetrad Analysis in Higher Plants. A Budding Technology
Gregory P. Copenhaver * , Kevin C. Keith and Daphne Preuss
+ Author Affiliations
1 Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
doi: http://dx.doi.org/10.1104/pp.124.1.7
Plant Physiology September 1, 2000 vol. 124 no. 1 7-16
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Abstract
Tetrad analysis, the ability to manipulate and individually study the four products of a single meiotic event, has been critical to understanding the mechanisms of heredity. The Arabidopsis quartet (qrt) mutation, which causes the four products of male meiosis to remain attached, enables plant biologists to apply this powerful tool to investigations of gamete development, cell division, chromosome dynamics, and recombination. Here we highlight several examples of how qrt has been used to perform tetrad analysis and suggest additional applications including a genetic screen for gametophytic mutants and methods for investigating gene interactions by synthetic lethal analysis.
In 1883 Van Beneden made an amazing observation: In newly fertilized Ascaris megalocephala eggs, the sperm and the egg nuclei each contained two chromosomes whereas the somatic cells contained four. Building on this observation, Weismann (1887) proposed that there must be a reductive cell division during the sexual life cycle to compensate for the fusion of gametes at fertilization. Farmer and Moore (1905)coined the term meiosis to describe this division. The cellular processes surrounding meiosis and the rules governing genetic inheritance have been the subjects of intense scientific scrutiny in the century since these early observations. During meiosis the cell reorganizes cytoplasmic components, initiates transcriptional programs, and activates specialized biosynthetic pathways. Equally dramatic events impact the genome: Each DNA strand is replicated, chromosomal homologs pair and recombine, and two cell divisions are executed to produce four haploid cells. Geneticists have employed several techniques to unravel the mechanisms of meiosis. Chief among these techniques is tetrad analysis, a method for investigating genetic mechanisms based upon the analysis of all four products of meiosis.
Tetrad analysis is particularly useful for examining meiotic recombination, and it has the flexibility to provide insight into many aspects of inheritance. Tetrad analysis can be used to detect chromosomal translocations, prove synthetic lethality in double mutants, and distinguish nuclear from organellar segregation. Similar to other methods for measuring recombination frequencies, tetrad analysis establishes linkage relationships that enable the construction of genetic maps (Mather and Beale, 1942). The most remarkable aspects of tetrad analysis are that it uniquely allows monitoring of every genetic exchange in an individual meiosis, unequivocal detection of gene conversion events, establishment of chromatid interference, and high precision genetic mapping of centromeres (Whitehouse, 1942; Mitchell, 1955; Fogel and Hurst, 1967). Because tetrad analysis requires the recovery of all four products of a meiosis, the analysis of complete tetrads has been historically restricted to fungal organisms and single-cell algae (Pascher, 1918). In contrast, the four meiotic products of higher eukaryotes either separate (male meiosis) or undergo selective cell death (female meiosis). The discovery of the quartet(qrt) mutant of Arabidopsis, a mutation that causes pollen grains to remain attached after cytokinesis (Fig.1), allowed the extension of tetrad analysis to a multicellular genetic model system (Preuss et al., 1994). While an understanding of the theory and practice of tetrad analysis is essential for anyone exploring genetic mechanisms, these techniques can be extended into many other areas, including development and cell biology. Here we describe the use of tetrad analysis in a higher plant, review recent examples from the literature, and suggest additional opportunities.
Fig. 1.
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Fig. 1.
Arabidopsis pollen development. The diploid pollen mother cell undergoes a round of DNA replication resulting in a meiocyte in which n = 4. During meiosis I, first division segregation (FDS) separates homologous chromosome pairs generating two cells in which n = 2. During meiosis II, second division segregation (SDS) separates sister chromatids and gives rise to four haploid cells. In Arabidopsis, pectin components in the exine wall of the pollen grains are degraded resulting in separation of the pollen tetrad. In qrt mutants, failure to degrade the pectin components leaves the pollen tetrad intact.
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CALCULATING LINKAGE WITH TETRAD ANALYSIS
The four meiotic products produced by qrt mutants, like those of Saccharomyces cerevisiae, are unordered, forming symmetrical tetrads with a geometry that does not reflect spindle orientation or the order of chromosome assortment. Marker pairs in these unordered tetrads assort in three possible patterns (Fig.2). In parental ditype (PD) tetrads, each meiotic product contains the same pair of alleles as one or the other parent. In non-parental ditype (NPD) tetrads, each meiotic product is recombinant, with novel allelic combinations. In tetratype tetrads (TT), each of the four meiotic products has a different genotype: two parental and two recombinant. These patterns of allelic segregation reveal the linkage relationships between genetic loci, including centromeres.
Fig. 2.
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Fig. 2.
Segregation analysis in tetrads. A, Two pairs of chromosomes are diagrammed progressing through meiosis. Each chromosome pair is composed of four chromatids; two from each parent (green and yellow, respectively). Upon completion of meiosis each member of the tetrad (i–iv) inherits one chromatid. The segregation of markers (X–Z) with different alleles (upper and lowercase) depends on the alignment of chromosomes at meiosis I and the distribution of recombination events (dashed lines). B, Scoring marker pairs in each tetrad member reveals three possible segregation patterns: parental ditype (PD), non-parental ditype (NPD), or tetratype (TT). Recombination can result in TT patterns. With markers on different chromosomes (Z and Y), crossovers between one of the markers and its centromere yields a TT; similarly, with linked markers (X and Y), a single crossover between them results in TT (not shown). C, Assigning each parental allele a “1” or a “0” value allows PD, NPD, and TT tetrad patterns to be converted to numerical data (2, 0, and 1, respectively).
When two loci are linked, PD tetrads are more abundant than NPD tetrads; if all of the tetrads are PD, the loci are completely linked. Single crossover events between linked loci yield TT tetrads, whereas double crossover events yield PD, TT, or NPD tetrads depending on the number of chromatids involved. The frequencies of each of these classes of tetrads can be used to calculate distances between linked markers with the equation: centiMorgans (cM) = [(1/2TT + 3NPD) ÷ total no. of tetrads] × 100.
Unlinked loci alternatively yield an equal number of PD and NPD tetrads; in such cases, the percentage of TT tetrads can be used to calculate the linkage of each locus to its centromere. During meiosis I, homologous chromosomes are drawn to opposite poles via their connection to the spindle apparatus at the centromere. Thus centromeres and centromere-linked genetic markers always segregate to opposite poles; pairs of centromere-linked markers that reside on different chromosomes yield only PD and NPD patterns. In contrast, recombination frequently separates distal markers from their centromeres, yielding a TT pattern when compared to centromere-linked markers (Fig. 2). The distance between these markers and their centromeres is determined by the equation: cM = (1/2TT) ÷ total no. of tetrads.
Similar calculations can be made using half-tetrad analysis, a special case of tetrad analysis that is possible when only two of the four meiotic products can be analyzed. This method has been used in several plant and animal species, including fruitflies (Drosophila melanogaster), zebra fish (Danio rerio), humans, alfalfa (Medicago sativa), potatoes (Solanum tuberosum), and corn (Zea mays) (Anderson, 1925;Rhoades and Dempsey, 1966; Mendiburu and Peloquin, 1979; Johnson et al., 1995; Tavoletti, 1996). Although half-tetrads can be used to map centromeres, they are less helpful when analyzing genetic events that require knowledge of all four meiotic products (such as gene conversion or chromatid interference).
The genetic segregation data that result from tetrad analysis often require repetitive calculations that can easily be accommodated with a computer spreadsheet program. Each marker allele can be represented by a “1” or “0,” making it possible to calculate PD, NPD, and TT frequencies quickly for any pair of markers (Fig. 2C). The frequencies of these classes can then be used with the mapping functions described above to determine genetic map distances. It is important to note that the frequency of TT tetrads for unlinked marker pairs can be used to calculate centromere positions.
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RESOURCES FOR TETRAD ANALYSIS IN ARABIDOPSIS
Since the discovery of the Arabidopsis qrt mutation, tetrad analysis has become an efficient tool for plant biologists. Lesions in either the QRT1 or QRT2 genes of Arabidopsis lead to defects in pectin degradation following male meiosis, preventing the normal separation of developing pollen grains from one another (Rhee and Somerville, 1998). This absence of normal separation results in fusion of the pollen exine walls, but leaves qrt pollen viable and fertile in every other respect (Preuss et al., 1994; Copenhaver et al., 1998). Because the fusion ofqrt pollen grains does not involve the inner intine wall, there is no mixing of cytoplasmic or nuclear components between the meiotic products. Although many other plants possess the capacity to package their meiotic products into pollen tetrads, including water lilies (Nymphaea), cattails (Typhaceae), heath (Ericaceae and Epacridceae), evening primroses (Onagraceae), sundews (Droseraceae), orchids (Orchidaceae), acacias (Mimosaceae), Dysoxylumspp. (Meliaceae), and petunias (Solanaceae) (Levan, 1942; Large and Mabberley, 1994; Preuss et al., 1994; Smyth, 1994), these organisms do not yet have the extensive genetic resources of Arabidopsis.
To determine the genotype of each member of a pollen tetrad, one could perform PCR analysis on individual grains (Matsunaga et al., 1999), a procedure that would require separation of the pollen, disruption of the exine layer, and efficient DNA amplification. The inherent technical difficulties, however, coupled with the limited number of loci that could be analyzed in each grain, make it preferable instead to obtain pollen tetrads that are segregating alleles of interest and to cross them to appropriate females and analyze the resulting progeny. For example, crossing two qrt plants from different ecotypes yields an F1 plant that is heterozygous for multiple polymorphisms (Fig. 3). These polymorphic markers segregate in the expected 2:2 ratio in the pollen tetrads produced by the F1 plant (Copenhaver et al., 1998). Pollen is collected from mature anthers by tapping them on a glass slide. A hair is attached to the end of a small wooden dowel and is subsequently used to lift a single pollen tetrad onto a stigma of an appropriate female. To avoid contamination from self-pollination, it is convenient to use stigmas from a male-sterile strain, such as ms1 (van der Veen and Wirtz, 1967). Crosses with individual pollen tetrads yield three or four seeds approximately 40% of the time. The tissue produced by these progeny yields sufficient DNA for thousands of PCR reactions, and their seeds provide a permanent resource for genetic analysis. The segregation of any type of genetic marker can be followed in the four progeny plants. Codominant PCR-based molecular markers such as simple sequence length polymorphisms, cleaved-amplified polymorphic sequences, and single nucleotide polymorphisms SNPs are reliable, easy to score even in large numbers, and require only a small amount of purified DNA (Konieczny and Ausubel, 1993; Bell and Ecker, 1994; Cho et al., 1999). RFLPs can also be used, but these markers require larger DNA preparations. Morphological markers have the advantage of rapid analysis if multiply marked parental lines are used to create the F1.
Fig. 3.
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Fig. 3.
Performing tetrad crosses in plants. Twoqrt parental strains (A and B) are crossed to produce aqrt F1 plant that is heterozygous for all the polymorphisms between the two parents. Individual pollen tetrads from the F1 plant are placed onto the stigmas of a receptor plant of known genotype (B). Each pollen grain in the tetrad fertilizes a different ovule resulting in four tetrad progeny.
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USING TETRAD ANALYSIS TO STUDY MEIOTIC MECHANISMS AND PLANT DEVELOPMENT
In addition to investigating the mechanisms of meiosis and recombination, tetrad analysis can also be used to identify key genes required for pollen development. Moreover, the ability to monitor the expression of genes within pollen grains provides practical tools that could enhance the efficiency of plant genetic screens. Below, we summarize recent studies that employed qrt for tetrad analysis and suggest future applications for this technology.
Analyzing Genes Required for Pollen Development
Although some gene products contained within pollen grains are derived from the sporophytic (diploid) parent, including the pre-meiotic pollen mother cell and the surrounding tapetal tissues, a large fraction of the pollen contents are expressed during the gametophytic (haploid) phase that follows meiosis. In some species, as many as 60% of the genes expressed during vegetative development are also expressed in haploid pollen, and approximately 10% of all genes in these species are pollen specific (Stinson et al., 1987). Theqrt mutation tremendously facilitates investigation of these haploid-specific genes. In heterozygotes, gametophytic mutant phenotypes segregate 2:2 in pollen tetrads; in contrast, genes under sporophytic control segregate in a 4:0 or 0:4 pattern for dominant or recessive mutations, respectively.
Tetrad analysis was used to prove the gametophytic function of two genes required for normal cell division in Arabidopsis pollen development: SIDECAR POLLEN (SCP) andGEMINI POLLEN1 (GEM1) (Chen and McCormick, 1996;Park et al., 1998). In the Nossen-0 and Columbia-0 ecotypes the scp mutation causes a mixture of wild-type, aborted, and extra-cell pollen, but in the Landsberg erecta ecotype it causes pollen lethality. By crossing scp to qrt, Chen and McCormick generated +/scp;qrt/qrt plants in a Nossen-0/Landsbergerecta mixed background. These plants produced pollen tetrads with two wild-type grains and two aborted grains, indicating that scp was acting as a gametophytic pollen lethal (Fig. 4). A similar strategy was used to examine gem1 mutants that produce twin-cell pollen grains due to an extra mitotic division during pollen development. Pollen produced by +/gem1; qrt/qrtplants never contained more than two aberrant grains but often contained fewer, indicating that gem1 is an incompletely penetrant gametophytic mutation. The qrt mutant was further utilized to examine the geometry of the extra mitotic divisions in gem1 pollen; in the aberrant pollen grains, these divisions were aligned on the normal division axis.
Fig. 4.
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Fig. 4.
Gametophytic segregation. Gametophytic genes are expressed in the haploid products of meiosis. Plants that are heterozygous for a male-specific gametophytic allele (g) will yield pollen grains that segregate the phenotype in a 2:2 ratio, which can be readily verified with qrt. Tetrads containing two aborted and two viable pollen grains occur with gametophytic lethal allele.
The qrt mutation can also be used to examine the uniformity of developmental events associated with individual meioses. Mutants in the Arabidopsis MEI1 gene undergo an aberrant meiosis, resulting in more than four pollen grains that vary in size and DNA content (He et al., 1996). To discern exactly how many cells are produced by individual meioses in MEI1 plants, He and Mascarenhas (1998) constructedMEI1-qrt double mutants, making it possible to isolate and count the meiotically related pollen clusters. The authors found significant variation in the number and size of cells within individual clusters and concluded that MEI1 could function in several stages of meiosis.
These studies demonstrate that qrt is useful for analyzing a variety of defects in pollen development. In fact, qrt can be used as the basis for a genetic screen designed to detect lesions in any gametophytically important gene. We have expressed a visible marker, green fluorescent protein, under the control of a pollen-specific promoter (G.P. Copenhaver, J. MacGurn, and D. Preuss, unpublished data). Following Agrobacterium tumefaciens-mediated transformation we found that insertions into gametophytic genes required for pollen development resulted in pollen tetrads with green fluorescent protein-marked, inviable pollen grains. Of 143 primary transformants surveyed, eight show a clear 2:2 aborted:viable phenotype in the pollen tetrads.
Constructing Genetic Maps
As diagrammed in Figure 2, marker assortment in tetrads can be used to construct genetic maps. With this approach, fewer recombinant individuals are required to obtain map distances, gene order can be readily defined by examining all four chromatids, and the distance at which linkage can be detected expands. We have used tetrad analysis to analyze recombination across the entire Arabidopsis genome, scoring all of the crossovers that occurred in individual meioses in Arabidopsis (Copenhaver et al., 1998). The number and distribution of crossover events in 57 meioses were measured by analyzing the segregation of 52 PCR-based markers spaced at approximately 10-cM intervals. This study revealed that the number of crossover events in each meiosis ranged from five to 13 with an average of 8.9 ± 1.8 (SD). Almost every chromosome experienced at least one crossover, suggesting that recombination is required for proper chromosome disjunction in Arabidopsis.
Crossover interference, a bias in the expected frequency of double crossovers, can also be measured with these techniques (Whitehouse, 1942). Chromosomal interference is detected when the expected frequency of double crossovers in adjacent genetic intervals differs significantly from the observed frequency of single crossovers in the individual intervals (Fig. 5A). In contrast, chromatid interference results in a non-random distribution of double crossovers on DNA strands, producing a deviation from the expected 1:2:1 ratio of two:three:four-strand double crossovers (Fig. 5B). Although chromosomal interference can be measured with other methods, chromatid interference requires knowledge of the crossover status of all four DNA strands at meiosis I and thus can be determined only with tetrad analysis. In our previous study of genomic recombination in Arabidopsis, significant chromosomal interference was observed (33 double crossovers observed versus 93 predicted), but chromatid interference was not detected on any chromosome (Copenhaver et al., 1998).
Fig. 5.
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Fig. 5.
Crossover interference. A, If crossovers are independent of one another the product of the frequencies (k) of single crossovers within adjacent intervals (k 1 and k 2) equals the frequency of double crossovers (k 3) in the combined interval (bracket). If the observed number of double crossovers within this region is less than the expected frequency then the interval is experiencing positive interference; in contrast, negative interference will yield more crossovers than expected. B, If crossovers are distributed randomly among the four chromatids (a–d), double crossovers should occur in a 1:2:1 ratio of two-strand:three-strand:four-strand events.
Detecting Gene Conversion
The physical replacement of one allele with another is known as gene conversion, an event that can result from mismatched repair of heteroduplex DNA during recombination (Mitchell, 1955; Meselson and Radding, 1975; Paques and Haber, 1999). Meiotic gene conversion events can be formally proven only with tetrad analysis; in contrast, when genetic analysis is performed with random gametes, closely spaced double crossovers are assumed to reflect gene conversion. Examination of all four chromatids, however, can discriminate between actual gene conversion events and other possibilities such as local negative interference. With tetrad analysis, an allele that undergoes gene conversion segregates in a 3:1 pattern (Fig.6), whereas flanking alleles segregate 2:2. It is surprising that in our work with Arabidopsis, we have yet to detect a gene conversion event. This observation may stem from insufficient marker density or may reflect an unexpectedly low frequency of gene conversion events.
Fig. 6.
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Fig. 6.
Detecting gene conversion in tetrads. Gene conversion occurs when genetic information is non-reciprocally transferred from one chromatid to another (orange and green bars) resulting in a non-Mendelian (3:1) segregation pattern. These events can be definitively detected with tetrad analysis because all four products of meiosis are available for inspection.
Identifying Regions That Provide Centromere Function
A number of methods have been used to map centromeres in higher eukaryotes, including plants. Chromosome breakage experiments localize centromeres by identifying chromosome fragments capable of autonomous segregation (Sears and Lee-Chen, 1970; Koornneef et al., 1983;Tyler-Smith et al., 1993; Murphy and Karpen, 1995; Sacchi et al., 1996). This method can be limited by the difficulty of obtaining desired breakpoints and by the activation of cryptic centromeres on acentric DNA fragments. Cytological methods alternatively reveal heterochromatic regions of the chromosome or localize proteins implicated in centromere function (Rattner, 1991; Sunkel and Coelho, 1995; Fransz et al., 1998). Such techniques can have limited resolution and cannot precisely identify the DNA sequences critical for centromere function. Several classes of repetitive DNA are known to colocalize with cytologically defined centromeres, but it is still unclear if these classes of DNA are required for centromere activity (Round et al., 1997).
As detailed above (Fig. 2), tetrad analysis can uniquely define the region of each chromosome that segregates to the cell pole in meiosis I. We took advantage of this property to map, with high precision, all five centromeres in Arabidopsis (Copenhaver et al., 1998, 1999). The same set of 57 tetrads used for the genome-wide scan of recombination provided an initial centromere position for each chromosome. By developing additional PCR-based markers, assembling contigs of bacteria artificial chromosome (BAC) clones, and scoring over 1,000 tetrads, we refined these initial centromere positions. This study revealed that the recombinationally suppressed centromeric regions of Arabidopsis encompass an array of repetitive elements and are flanked by regions rich in mobile DNA elements. Despite their repetitive nature, the Arabidopsis centromeres contain many genes. We are currently extending these studies by using tetrad analysis to assess the assortment of chromosome fragments, aberrant chromosomes containing two centromeres, and synthetic minichromosomes (K.C. Keith and D. Preuss, unpublished data).
Detecting Chromosome Rearrangements
Since the construction of the earliest fruitfly mapping strains, balancer chromosomes that contain translocations or inversions have been recognized as important genetic tools (Casso et al., 2000). In plants, these rearrangements can often occur inadvertently as a consequence of Agrobacterium tumefaciens-mediated plant transformation (Castle et al., 1993; Nacry et al., 1998). Tetrad analysis is a useful method for rapidly detecting and analyzing these aberrations.
A plant that is heterozygous for a balanced translocation can undergo two types of meiotic segregation: adjacent or alternate (Fig.7). In the latter case, all four meiotic products contain a balanced set of chromosomes, but in the former case, all four meiotic products have duplications and deficiencies that are usually lethal. Because the frequencies of adjacent and alternate segregation patterns are approximately equal, a qrt plant heterozygous for a translocation will yield equal numbers of tetrads containing all aborted or all wild-type pollen grains. Ray et al. (1997) took advantage of this property to confirm that they had found a desired reciprocal translocation, TL-1, caused by T-DNA mutagenesis. In their strains, qrt plants showed an aborted pollen phenotype that segregated in a 4:0 and 0:4 pattern with equal frequency. This line also produced some pollen tetrads segregating aborted pollen in 3:1, 2:2, and 1:3 patterns, suggesting that recombination events capable of restoring a balanced chromosome set were occurring. Using these strains, Ray et al. (1997) subsequently showed that, as expected, one-half of the female meioses were also aberrant and that the resulting defective female gametophytes were incapable of attracting pollen tubes.
Fig. 7.
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Fig. 7.
Chromosome segregation in translocation heterozygotes. In individuals heterozygous for a reciprocal translocation, the affected chromosomes form a tetravalent structure upon pairing. During meiosis I homologous centromeres (1–4) disjoin and migrate to the cell poles. Segregation in a tetravalent can occur in two ways: either adjacent chromosomes (1 and 3) or alternate chromosomes (1 and 4) can migrate to the same pole. In rare cases, homologous centromeres fail to disjoin and a second form of adjacent segregation (adjacent-2) can occur.
Non-Mendelian Inheritance
Whereas tetrad segregation patterns of 2:2 indicate that a particular phenotype is under the control of the nuclear genome, consistent 0:4 or 4:0 patterns suggest that the phenotype is determined by an organelle, such as the mitochondrial or chloroplast genome, or is a cytoplasmic component inherited from the precursor diploid cell. When plants with two different organelle genotypes are crossed, the resulting F1 will typically have the composition of the maternal parent, since most plants show maternal inheritance of organelles (Birky, 1978). The pollen tetrads from the F1 will consequently segregate in a 4:0 pattern, reflecting the maternal allele. A similar effect is seen in yeast; although both parent cells contribute organelles to the F1 zygote, subsequent mixing and distribution of organelles results in uniform 4:0 inheritance in the spores (Wolf et al., 1978).
During our effort to map the centromeres in Arabidopsis, the ability to distinguish between nuclear and organelle inheritance with tetrad analysis was critically important. As DNA clones were identified for sequencing on chromosome II, a BAC clone that contained nDNA fused to DNA that was highly similar to the sequence of the Arabidopsis mitochondrial genome was characterized (Unseld et al., 1997; Lin et al., 1999). The identification of a second BAC clone with a different mitochondrial-nuclear junction raised the possibility that these clones corresponded to a large insertion of mitochondrial DNA into the nuclear genome rather than chimeric constructs formed during construction of the libraries. To test whether there was indeed a large mitochondrial insertion into the chromosome, we designed PCR primers that detected polymorphisms at the junction of the nuclear and mitochrondrial DNA. Scoring these markers in the tetrads used to map the centromeres showed, in every case, a 2:2 pattern, confirming a large (270 kb) insert of the mitochondrial genome into chromosome II.
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FUTURE OPPORTUNITIES: INVESTIGATING GENETIC REDUNDANCY
The enormous number of duplicated genes within the Arabidopsis genome will require creative approaches aimed at discerning gene function. It is imperative to investigate mutations in combinations that can reveal genetic interactions, including those interactions that result in synthetic lethality. The latter is a particularly useful phenomenon that has been important for discerning the functions of numerous genes in yeast and other organisms (Huffaker et al., 1987). Two mutations are described as having a synthetically lethal phenotype when their combination results in a non-viable double mutant. Such lethality raises the possibility that the genes contribute to the same biological process. Tetrad analysis provides essential proof that the desired double mutant is indeed lethal. By analyzing only a few NPD tetrads one can conclude that the mutations are synthetically lethal if the two surviving individuals always have a wild-type genotype. In contrast, providing such proof with a randomly segregating population requires large numbers of progeny and relies on statistical analysis.
We recommend the following methods when incorporating this approach in plants. Two qrt parental strains each homozygous for a different mutation should be crossed to each other to generate an F1. In the pollen tetrads from this F1, the mutant and wild-type alleles will segregate into PD, NPD, and TT patterns. If the genes play a gametophytic role in pollen development, then synthetic lethality will result in pollen tetrads that segregate viable:aborted pollen grains in 4:0, 3:1, and 2:2 patterns. Those tetrads exhibiting a 2:2 segregation pattern should then be crossed to an appropriate female to ensure that the two surviving pollen grains contain only wild-type gametes.
The tetrad is an addition to the famous dark triad. The fourth is always different
"Dark Tetrad" of personality traits: Everyday sadists take pleasure in others' pain
Anna Mikulak
Association for Psychological Science
Thu, 12 Sep 2013 12:23 UTCMap
Most of the time, we try to avoid inflicting pain on others - when we do hurt someone, we typically experience guilt, remorse, or other feelings of distress. But for some, cruelty can be pleasurable, even exciting. New research suggests that this kind of everyday sadism is real and more common than we might think.
Two studies led by psychological scientist Erin Buckels of the University of British Columbia revealed that people who score high on a measure of sadism seem to derive pleasure from behaviors that hurt others, and are even willing to expend extra effort to make someone else suffer.
The new findings are published in Psychological Science, a journal of the Association for Psychological Science.
"Some find it hard to reconcile sadism with the concept of 'normal' psychological functioning, but our findings show that sadistic tendencies among otherwise well-adjusted people must be acknowledged," says Buckels. "These people aren't necessarily serial killers or sexual deviants but they gain some emotional benefit in causing or simply observing others' suffering."
Based on their previous work on the "Dark Triad" of personality, Buckels and colleagues Delroy Paulhus of the University of British Columbia and Daniel Jones of the University of Texas El Paso surmised that sadism is a distinct aspect of personality that joins with three others - psychopathy, narcissism, and Machiavellianism - to form a "Dark Tetrad" of personality traits.
To test their hypothesis, they decided to examine everyday sadism under controlled laboratory conditions. They recruited 71 participants to take part in a study on "personality and tolerance for challenging jobs." Participants were asked to choose among several unpleasant tasks: killing bugs, helping the experimenter kill bugs, cleaning dirty toilets, or enduring pain from ice water.
Participants who chose bug killing were shown the bug-crunching machine: a modified coffee grinder that produced a distinct crunching sound so as to maximize the gruesomeness of the task. Nearby were cups containing live pill bugs, each cup labeled with the bug's name: Muffin, Ike, and Tootsie.
The participant's job was to drop the bugs into the machine, force down the cover, and "grind them up." The participants didn't know that a barrier actually prevented the bugs from being ground up and that no bugs were harmed in the experiment.
Of the 71 participants, 12.7% chose the pain-tolerance task, 33.8% chose the toilet-cleaning task, 26.8% chose to help kill bugs, and 26.8% chose to kill bugs.
Participants who chose bug killing had the highest scores on a scale measuring sadistic impulses, just as the researchers predicted. The more sadistic the participant was, the more likely he or she was to choose bug killing over the other options, even when their scores on Dark Triad measures, fear of bugs, and sensitivity to disgust were taken into account.
Participants with high levels of sadism who chose to kill bugs reported taking significantly greater pleasure in the task than those who chose another task, and their pleasure seemed to correlate with the number of bugs they killed, suggesting that sadistic behavior may hold some sort of reward value for those participants.
And a second study revealed that, of the participants who rated high on one of the "dark" personality traits, only sadists chose to intensify blasts of white noise directed at an innocent opponent when they realized the opponent wouldn't fight back. They were also the only ones willing to expend additional time and energy to be able to blast the innocent opponent with the noise.
Together, these results suggest that sadists possess an intrinsic motivation to inflict suffering on innocent others, even at a personal cost - a motivation that is absent from the other dark personality traits.
The researchers hope that these new findings will help to broaden people's view of sadism as an aspect of personality that manifests in everyday life, helping to dispel the notion that sadism is limited to sexual deviants and criminals.
Buckels and colleagues are continuing to investigate everyday sadism, including its role in online trolling behavior.
"Trolling culture is unique in that it explicitly celebrates sadistic pleasure, or 'lulz,'" says Buckels. "It is, perhaps, not surprising then that sadists gravitate toward those activities."
And they're also exploring vicarious forms of sadism, such as enjoying cruelty in movies, video games, and sports.
The researchers believe their findings have the potential to inform research and policy on domestic abuse, bullying, animal abuse, and cases of military and police brutality.
"It is such situations that sadistic individuals may exploit for personal pleasure," says Buckels. "Denying the dark side of personality will not help when managing people in these contexts."
https://www.sott.net/…/266289-Dark-Tetrad-of-personality-tr…
The form of an amino acid is a quadrant with the fourth part being different
https://www.ncbi.nlm.nih.gov/books/NBK21581/
Amino acids are the monomeric building blocks of proteins. The α carbon atom (Cα) of amino acids, which is adjacent to the carboxyl group, is bonded to four different chemical groups: an amino (NH2) group, a carboxyl (COOH) group, a hydrogen (H) atom, and one variable group, called a side chain or R group (Figure 3-1). All 20 different amino acids have this same general structure, but their side-chain groups vary in size, shape, charge, hydrophobicity, and reactivity.
https://en.wikipedia.org/wiki/Cerebrum
In the developing vertebrate embryo, the neural tube is subdivided into FOUR unseparated sections which then develop further into distinct regions of the central nervous system; these are the prosencephalon (forebrain), the mesencephalon (midbrain) the rhombencephalon (hindbrain) and the spinal cord.[
https://en.wikipedia.org/wiki/Protein_contact_map
A protein contact map is in the form of a quadrant.
A protein contact map represents the distance between all possible amino acid residue pairs of a three-dimensional protein structure using a binary two-dimensional matrix. For two residues i and j, the ij element of the matrix is 1 if the two residues are closer than a predetermined threshold, and 0 otherwise. Various contact definitions have been proposed: The distance between the Cα-Cα atom with threshold 6-12 Å; distance between Cβ-Cβ atoms with threshold 6-12 Å (Cα is used for Glycine); and distance between the side-chain centers of mass.
In representations of the HB plot, characteristic patterns of secondary structure elements can be recognised easily, as follows:
Helices can be identified as strips directly adjacent to the diagonal.
Antiparallel beta sheets appear in HB plot as cross-diagonal.
Parallel beta sheets appears in the HB plot as parallel to the diagonal.
Loops appear as breaks in the diagonal between the cross-diagonal beta-sheet motifs.
https://en.wikipedia.org/wiki/Wobble_base_pair
A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules.[1] The FOUR main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A), and hypoxanthine-cytosine (I-C). In order to maintain consistency of nucleic acid nomenclature, "I" is used for hypoxanthine because hypoxanthine is the nucleobase of inosine;[2] nomenclature otherwise follows the names of nucleobases and their corresponding nucleosides (e.g., "G" for both guanine and guanosine). The thermodynamic stability of a wobble base pair is comparable to that of a Watson-Crick base pair. Wobble base pairs are fundamental in RNA secondary structure and are critical for the proper translation of the genetic code.
Wobble hypothesis[edit]
These notions led Francis Crick to the creation of the wobble hypothesis, a set of FOUR relationships explaining these naturally occurring attributes.
The first two bases in the codon create the coding specificity, for they form strong Watson-Crick base pairs and bond strongly to the anticodon of the tRNA.
When reading 5' to 3' the first nucleotide in the anticodon (which is on the tRNA and pairs with the last nucleotide of the codon on the mRNA) determines how many nucleotides the tRNA actually distinguishes.
If the first nucleotide in the anticodon is a C or an A pairing is specific and acknowledges original Watson-Crick pairing, that is only one specific codon can be paired to that tRNA. If the first nucleotide is U or G, the pairing is less specific and in fact two bases can be interchangeably recognized by the tRNA. Inosine displays the true qualities of wobble, in that if that is the first nucleotide in the anticodon then any of three bases in the original codon can be matched with the tRNA.
Due to the specificity inherent in the first two nucleotides of the codon, if one amino acid codes for multiple anticodons and those anticodons differ in either the second or third position (first or second position in the codon) then a different tRNA is required for that anticodon.
The minimum requirement to satisfy all possible codons (61 excluding three stop codons) is 32 tRNAS. That is 31 tRNA's for the amino acids and one initiation codon.[8]
ADHESION MOLECULES FORM OF THE SWASTIKA
http://survincity.com/2010/12/swastika-myths-and-realities-2/
The writings Bagdasarova have interesting information about the swastika for people prone to the scientific knowledge of the world. "Archetype swastika played at all levels of the universe. Confirmation of this — follow the migration of cells and cell layers, in which the structure of fixed micro-shaped swastika. It is a cell adhesion molecules. (Adhesion, one of the primary processes of development, means sticking, cell attachment to each other, without which there can be no embryo).
Adhesion molecule (IAC) form structures, each branch of which is a protein chain. " IAC photos taken with an electron microscope, look like three-and four-armed swastika. "Thus, the expression of the MAC process (creation of the microcosm), available human eye in the form of a swastika, the model reproduces the shape of the universe (the macrocosm) …" has the same structure as our galaxy, seen pictures of the universe from space. Therefore, the swastika is very attractive for astrophysics and geophysics. And perhaps it is with these facts relate mystical and esoteric aspects of the symbolism of the swastika.
Thus, we see that the sign of the swastika permeates our being from micro to macro and occurs everywhere in our lives, but our contemporaries (particularly in the former Soviet Union), have lost the ancient knowledge and cultural traditions of generations, sometimes about it and not know it. And it becomes clear why our ancestors thought the swastika sign Creator called sacred symbol and so carefully carried the tradition of transmission of knowledge from generation to generation.
Tamara Bogdanova.
I'm a paragraph. Click here to add your own text and edit me. It's easy.
https://en.wikipedia.org/wiki/Prokaryote
Prokaryotic cells have various shapes; the four basic shapes of bacteria are:[9]
Cocci – spherical
Bacilli – rod-shaped
Spirochaete – spiral-shaped
Vibrio – comma-shaped
APPEAR IN TETRADS (groups of four)
https://en.wikipedia.org/wiki/Micrococcus
Micrococcus (mi’ krō kŏk’ Əs) is a genus of bacteria in the Micrococcaceae family. Micrococcus occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from about 0.5 to 3 micrometers in diameter and typically appear in tetrads
https://en.wikipedia.org/wiki/Body_plan
Cuvier, 1817[edit]
Haeckel's 'Monophyletischer Stambaum der Organismen' from Generelle Morphologie der Organismen (1866) with the three branches Plantae, Protista, Animalia
In his 1817 work, Le Règne Animal, the French zoologist Georges Cuvier combined evidence from comparative anatomy and palaeontology[3] to divide the animal kingdom into four body plans. Taking the central nervous system as the main organ system which controlled all the others, such as the circulatory and digestive systems, Cuvier distinguished four body plans:[4]
I. with a brain and a spinal cord (surrounded by skeletal elements)[4]
II. with organs linked by nerve fibres[4]
III. with two longitudinal, ventral nerve cords linked by a band with two ganglia below the oesophagus[4]
IV. with a diffuse nervous system, not clearly discernible[4]
Grouping animals with these body plans resulted in four branches: vertebrates, molluscs, articulata (including insects and annelids) and zoophytes or radiata.
https://en.wikipedia.org/wiki/Evolutionary_developmental_biology
Von Baer instead recognised four distinct animal body plans: radiate, like starfish; molluscan, like clams; articulate, like lobsters; and vertebrate, like fish. Zoologists then largely abandoned recapitulation, though Ernst Haeckel revived it in 1866.[2][3][4][5][6]
https://en.wikipedia.org/wiki/Giraffe
The four-species taxonomic classification, proposed in 2016 but criticized since then, has the genus Giraffa composed of the species Giraffa giraffa (southern giraffe), Giraffa tippelskirchi (Masai giraffe), Giraffa reticulata (reticulated giraffe) and Giraffa camelopardalis (northern giraffe).
BLOODS FOUR COMPONENTS
https://en.wikipedia.org/wiki/Blood
Jehovah's Witnesses[edit]
Main article: J- Witnesses and blood transfusions
Based on their interpretation of scriptures such as Acts 15:28, 29 ("Keep abstaining...from blood."), many J- Witnesses neither consume blood nor accept transfusions of whole blood or its major components: red blood cells, white blood cells, platelets (thrombocytes), and plasma. Members may personally decide whether they will accept medical procedures that involve their own blood or substances that are further fractionated from the four major components.[39]
THE FOURTH IS ALWAYS DIFFERENT- THE FOURTH KIND OF VESSEL
https://en.wikipedia.org/wiki/Lymphatic_system
The lacteals were termed the fourth kind of vessels (the other three being the artery, vein and nerve, which was then believed to be a type of vessel), and disproved Galen's assertion that chyle was carried by the veins.
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FOUR STAGES OF GROWTH
https://en.wikipedia.org/wiki/Triceratops
Growth and ontogeny[edit]
Skull growth series
In 2006, the first extensive ontogenetic study of Triceratops was published in the journal Proceedings of the Royal Society. The study, by John R. Horner and Mark Goodwin, found that individuals of Triceratops could be divided into four general ontogenetic groups, babies, juveniles, subadults, and adults. With a total number of 28 skulls studied, the youngest was only 38 cm (15 in) long. 10 of the 28 skulls could be placed in order in a growth series with one representing each age. Each of the four growth stages were found to have identifying features. Multiple ontogenetic trends were discovered, including the size reduce of the epoccipitals, development and reorientation of postorbital horns, and hollowing out of the horns.[82]
http://dune.wikia.com/wiki/Dune_(1984_movie)
Four planets draw the attention of the Spacing Guild: Arrakis, a desert planet and only source in the universe of the spice; Caladan, home of House Atreides; Giedi Prime, home of House Harkonnen; and Kaitain, Home of the Emperor Shaddam IV. The Guild, fearing a plot that might jeopardize Spice production, send a third stage Navigator to Kaitain demanding explanations from the Emperor, who confidentially lets the Guild know of his plans to destroy House Atreides. The popularity of Duke Leto Atreides has grown within the Landsraad, and he is suspected to be creating a secret army with a technique involving sound, making him a formidable threat to the Emperor. Shaddam's plan is to give the Atreides control of Arrakis, replacing the Harkonnens, who at an appointed time would launch a sneak attack on the Atreides, eliminating them. Upon being informed of the plot, the Navigator commands the Emperor to kill the Duke's son, Paul Atreides, a young man who dreams prophetic visions of his purpose. The cryptic assassination order draws the attention of the Bene Gesserit sisterhood, as Paul Atreides is part of a centuries long breeding program in the search of the Kwisatz Haderach.
http://www.independent.co.uk/…/giraffe-species-dna-genes-mo…
Giraffes are divided into four distinct species, not just one, scientists discover
https://en.wikipedia.org/wiki/American_crocodile
The American crocodile (Crocodylus acutus) is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas.
https://en.wikipedia.org/wiki/Bison
A 2003 study of mitochondrial DNA indicated four distinct maternal lineages in tribe Bovini:
Taurine cattle and zebu
Wisent
American bison and yak[14] and
Banteng, gaur, and gayal
FOURTH DIFFERENT
https://en.wikipedia.org/wiki/Bison
There are also remnant purebred American bison herds on public lands in North America. Three herds are in Yellowstone National Park, Wind Cave National Park in South Dakota and Elk Island National Park in Alberta, Canada. In 2015 a fourth purebred herd of 350 individuals was identified on public lands in the Henry Mountains of southern Utah via genetic testing of mitochondrial and nuclear DNA.[32] This study, published in 2015, also showed the Henry Mountains bison herd to be free of brucellosis, a bacterial disease that was imported with non-native domestic cattle to North America.[33]
https://en.wikipedia.org/wiki/Tsetse_fly
FOUR FAMILIES
Tsetse are in the order Diptera, the true flies. They belong to the superfamily Hippoboscoidea, in which the tsetse's family, the Glossinidae, is one of four families of blood-feeding obligate parasites.
https://en.wikipedia.org/wiki/Fly
Diptera go through a complete metamorphosis with four distinct life stages – egg, larva, pupa and adult
FOUR FAMILIES
https://en.wikipedia.org/wiki/Hippoboscoidea
Hippoboscoidea is a superfamily of the Calyptratae. The flies in this superfamily are blood-feeding obligate parasites of their hosts. Four families are often placed here:
Glossinidae - Tsetse flies
Hippoboscidae - Ked flies
Nycteribiidae - Bat flies
Streblidae - Bat flies
16 SQUARES QUADRANT MODEL
https://en.wikipedia.org/wiki/Louisiana_black_bear
The Louisiana black bear (Ursus americanus luteolus), one of 16 subspecies of the American black bear, is found in parts of Louisiana, mainly along the Mississippi River Valley and the Atchafalaya River Basin.
https://en.wikipedia.org/wiki/Fourhorn_sculpin
The fourhorn sculpin (Myoxocephalus quadricornis or Triglopsis quadricornis) is a species of fish in the Cottidae family. It is a demersal fish distributed mainly in brackish arctic coastal waters in Canada, Greenland, Russia, and Alaska, and also as a relict in the boreal Baltic Sea. There are also freshwater populations in the lakes of Norway, Sweden, Finland and Karelia (NW Russia) and in Arctic Canada (Nunavut and Northwest Territories).
The fourhorn sculpin has a large knobbly head with protruding lips and four bony protuberances, though the latter are not present in freshwater, lake forms of this fish.
BIG FOUR SNAKES
https://en.wikipedia.org/wiki/Indian_cobra
The Indian cobra (Naja naja) also known as the spectacled cobra, Asian cobra or binocellate cobra is a species of the genus Naja found in the Indian subcontinent (India, Pakistan, Bangladesh, Sri Lanka, Nepal) and a member of the "big four" species that inflict the most snakebites on humans in India
FOUR SUBSPECIES
https://en.wikipedia.org/wiki/Tiliqua_rugosa
Tiliqua rugosa is a short-tailed, slow moving species of blue-tongued skink found in Australia. Three of the four[2] recognised subspecies are found only in Western Australia, where they are known collectively by the common name bobtail.[3] The name shingleback is also used, especially for T. rugosa asper, the only subspecies native to eastern Australia.
Four subspecies of T. rugosa are currently recognized:[2]
T. r. rugosa: bobtail or western shingleback – Western Australia
T. r. asper:[5] eastern shingleback – eastern Australia
T. r. konowi:[6] Rottnest Island bobtail or Rottnest Island shingleback – Rottnest Island, Western Australia
T. r. palarra:[7] northern bobtail or Shark Bay shingleback – Shark Bay, Western Australia
FOUR SPECIES
https://en.wikipedia.org/wiki/Woolly_monkey
The woolly monkeys are the genus Lagothrix of New World monkeys, usually placed in the family Atelidae.
The four species of woolly monkeys all originate from the rainforests of South America. They have prehensile tails and live in relatively large social groups.
FOUR DIVISIONS ARCHAEA
Consequently, until the advent of molecular phylogeny, the Kingdom Prokaryotae was divided into four divisions,[40] A classification scheme still formally followed by Bergey's manual of systematic bacteriology for tome order[41]
https://en.wikipedia.org/wiki/Bacterial_taxonomy
Gracilicutes (gram-negative)
Photobacteria (photosynthetic): class Oxyphotobacteriae (water as electron donor, includes the order Cyanobacteriales=blue-green algae, now phylum Cyanobacteria) and class Anoxyphotobacteriae (anaerobic phototrophs, orders: Rhodospirillales and Chlorobiales
Scotobacteria (non-photosynthetic, now the Proteobacteria and other gram-negative nonphotosynthetic phyla)
Firmacutes [sic] (gram-positive, subsequently corrected to Firmicutes[42])
several orders such as Bacillales and Actinomycetales (now in the phylum Actinobacteria)
Mollicutes (gram variable, e.g. Mycoplasma)
Mendocutes (uneven gram stain, "methanogenic bacteria", now known as the Archaea)
Under environmental conditions which are favourable for reproduction, hatched larvae develop through four stages or molts, designated as L1 to L4. When conditions are stressed as in food insufficiency, C. elegans can enter an alternative third larval stage called the dauer state. Dauer is German for permanent. Dauer larvae are stress-resistant; they are thin and their mouths are sealed and cannot take in food, and they can remain in this stage for a few months.[23] Hermaphrodites produce all their sperm in the L4 stage (150 sperm per gonadal arm) and then produce only oocytes. The sperm cells are stored in the same area of the gonad as the oocytes until the first oocyte pushes the sperm into the spermatheca (a chamber wherein the oocytes become fertilized by the sperm).[24]
TETRAPODA FOUR CLASSES
https://en.wikipedia.org/wiki/Amphibian
The superclass Tetrapoda is divided into four classes of vertebrate animals with four limbs.[23] Reptiles, birds and mammals are amniotes, the eggs of which are either laid or carried by the female and are surrounded by several membranes, some of which are impervious.[24] Lacking these membranes, amphibians require water bodies for reproduction, although some species have developed various strategies for protecting or bypassing the vulnerable aquatic larval stage.[22] They are not found in the sea with the exception of one or two frogs that live in brackish water in mangrove swamps.[25] On land, amphibians are restricted to moist habitats because of the need to keep their skin damp.[22]
https://en.wikipedia.org/wiki/Leiopelmatidae
The four extant species of Leiopelmatidae are only found in New Zealand
Family LEIOPELMATIDAE
Genus Leiopelma
Archey's frog, Leiopelma archeyi Turbott, 1942
Hamilton's frog, Leiopelma hamiltoni McCulloch, 1919
Hochstetter's frog, Leiopelma hochstetteri Fitzinger, 1861
Maud Island frog, Leiopelma pakeka Bell, Daugherty & Hay, 1998
https://en.wikipedia.org/wiki/Doberman_Pinscher
FOUR COLOR PHENOTYPES
IN addition to the studies of canine personality, there has been some research to determine whether there are breed differences in aggression. In a study published in 2008, aggression was divided into four categories: aggression directed at strangers, owner, strange dogs and rivalry with other household dogs.[21] This study found that the Doberman Pinscher ranked relatively high on stranger-directed aggression, but extremely low on owner-directed aggression. The Doberman Pinscher ranked as average on dog-directed aggression and dog rivalry. Looking only at bites and attempted bites, Doberman Pinschers rank as far less aggressive towards humans, and show less aggression than many breeds without a reputation (e.g., Cocker Spaniel, Dalmatian, and Great Dane). This study concluded that aggression has a genetic basis, that the Doberman shows a distinctive pattern of aggression depending on the situation, and that contemporary Doberman Pinschers are not an aggressive breed overall.[21] In regards to dobermans attacking owners, it is rare and usually in the case of over discipline. Dobermans accept physical punishment to an extent, however, when they consider it is no longer punishment and is an attack on themselves, they will defend
FOUR SUBORDERS
https://en.wikipedia.org/wiki/Hemiptera
The present members of the order Hemiptera (sometimes referred to as Rhynchota) were historically placed into two orders, the so-called Homoptera and Heteroptera/Hemiptera, based on differences in wing structure and the position of the rostrum. The order is now divided into four or more suborders, after the "Homoptera" were established as paraphyletic (now the Auchenorrhyncha and the Sternorrhyncha)
FOUR DISTINCT WADER LINEAGES- FOUR suborders
https://en.wikipedia.org/wiki/Wader
In keeping more in line with the traditional grouping, the Thinocori could be included in the Scolopaci, and the Chionidi in the Charadrii. However, the increasing knowledge about the early evolutionary history of modern birds suggests that the assumption of Paton et al. (2003) and Thomas et al. (2004b) of FOUR distinct "wader" lineages (= suborders) already being present around the Cretaceous–Paleogene boundary is correct.
Suborder Scolopaci
Family Scolopacidae: snipe, sandpipers, phalaropes, and allies
Suborder Thinocori
Family Rostratulidae: painted snipe
Family Jacanidae: jacanas
Family Thinocoridae: seedsnipe
Family Pedionomidae: plains wanderer
Suborder Chionidi
Family Burhinidae: thick-knees
Family Chionididae: sheathbills
Family Pluvianellidae: Magellanic plover
Suborder Charadrii
Family Ibidorhynchidae: ibisbill
Family Recurvirostridae: avocets and stilts
Family Haematopodidae: oystercatchers
Family Charadriidae: plovers and lapwings
FOUR MECHANORECEPTORS
https://en.wikipedia.org/wiki/Mechanoreceptor
A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous skin: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini endings. There are also mechanoreceptors in hairy skin, and the hair cells in thoreceptors of primates like rhesus monkeys and other mammals are similar to those of humans and also studied even in early 20th century anatomically and neurophysiologically.[1]
FOUR STAGES EVOLUITON OF EYE
https://en.wikipedia.org/wiki/Evolution_of_the_eye
D.E. Nilsson has independently put forth four theorized general stages in the evolution of a vertebrate eye from a patch of photoreceptors.[5] Nilsson and S. Pelger published a classical paper theorizing how many generations are needed to evolve a complex eye in vertebrates.[6] Another researcher, G.C. Young, has used fossil evidence to infer evolutionary conclusions, based on the structure of eye orbits and openings in fossilized skulls for blood vessels and nerves to go through.[7] All this evidence adds to the growing amount of evidence that supports Darwin's theory.
FOUR SUBSPECIES
https://en.wikipedia.org/wiki/Glaucous_gull
The glaucous gull (Larus hyperboreus) is a large gull, the second largest gull in the world which breeds in Arctic regions of the Northern Hemisphere and winters south to shores of the Holarctic.
Subspecies[edit]
There are four subspecies:
L. h. hyperboreus, Gunnerus, 1767: nominate, found from northern Europe to north-western Siberia
L. h. pallidissimus, Portenko, 1939: found from north-western Siberia to the Bering Sea
L. h. barrovianus, Ridgway, 1886: found from Alaska to north-west Canada
L. h. leuceretes, Schleep, 1819: found from north-central Canada to Greenland and Iceland
TETRA IS FOUR- TETRAPEPTIDE
https://en.wikipedia.org/wiki/Cholecystokinin
The CCK tetrapeptide fragment CCK-4 (Trp-Met-Asp-Phe-NH2) reliably causes anxiety and panic attacks (panicogenic effect) when administered to humans and is commonly used in scientific research for this purpose of in order to test new anxiolytic drugs.[17][18] Positron emission tomography visualization of regional cerebral blood flow in patients undergoing CCK-4 induced panic attacks show changes in the anterior cingulate gyrus, the claustrum-insular-amygdala region, and cerebellar vermis.[16]
I'm a paragraph. Click here to add your own text and edit m
FOUR STAGES
https://en.wikipedia.org/wiki/Alzheimer%27s_disease
The disease course is divided into four stages, with a progressive pattern of cognitive and functional impairment.
Pre-dementia
The first symptoms are often mistakenly attributed to ageing or stress.[20] Detailed neuropsychological testing can reveal mild cognitive difficulties up to eight years before a person fulfils the clinical criteria for diagnosis of AD.[21] These early symptoms can affect the most complex activities of daily living.[22] The most noticeable deficit is short term memory loss, which shows up as difficulty in remembering recently learned facts and inability to acquire new information.[21][23]
Subtle problems with the executive functions of attentiveness, planning, flexibility, and abstract thinking, or impairments in semantic memory (memory of meanings, and concept relationships) can also be symptomatic of the early stages of AD.[21] Apathy can be observed at this stage, and remains the most persistent neuropsychiatric symptom throughout the course of the disease.[24] Depressive symptoms, irritability and reduced awareness of subtle memory difficulties are also common.[25] The preclinical stage of the disease has also been termed mild cognitive impairment (MCI).[23] This is often found to be a transitional stage between normal ageing and dementia. MCI can present with a variety of symptoms, and when memory loss is the predominant symptom, it is termed "amnestic MCI" and is frequently seen as a prodromal stage of Alzheimer's disease.[26]
Early
In people with AD, the increasing impairment of learning and memory eventually leads to a definitive diagnosis. In a small percentage, difficulties with language, executive functions, perception (agnosia), or execution of movements (apraxia) are more prominent than memory problems.[27] AD does not affect all memory capacities equally. Older memories of the person's life (episodic memory), facts learned (semantic memory), and implicit memory (the memory of the body on how to do things, such as using a fork to eat or how to drink from a glass) are affected to a lesser degree than new facts or memories.[28][29]
Language problems are mainly characterised by a shrinking vocabulary and decreased word fluency, leading to a general impoverishment of oral and written language.[27][30] In this stage, the person with Alzheimer's is usually capable of communicating basic ideas adequately.[27][30][31] While performing fine motor tasks such as writing, drawing or dressing, certain movement coordination and planning difficulties (apraxia) may be present, but they are commonly unnoticed.[27] As the disease progresses, people with AD can often continue to perform many tasks independently, but may need assistance or supervision with the most cognitively demanding activities.[27]
Moderate
A photograph of a patient at West Riding Lunatic Asylum with dementia
Progressive deterioration eventually hinders independence, with subjects being unable to perform most common activities of daily living.[27] Speech difficulties become evident due to an inability to recall vocabulary, which leads to frequent incorrect word substitutions (paraphasias). Reading and writing skills are also progressively lost.[27][31] Complex motor sequences become less coordinated as time passes and AD progresses, so the risk of falling increases.[27] During this phase, memory problems worsen, and the person may fail to recognise close relatives.[27] Long-term memory, which was previously intact, becomes impaired.[27]
Behavioural and neuropsychiatric changes become more prevalent. Common manifestations are wandering, irritability and labile affect, leading to crying, outbursts of unpremeditated aggression, or resistance to caregiving.[27] Sundowning can also appear.[32] Approximately 30% of people with AD develop illusionary misidentifications and other delusional symptoms.[27] Subjects also lose insight of their disease process and limitations (anosognosia).[27] Urinary incontinence can develop.[27] These symptoms create stress for relatives and carers, which can be reduced by moving the person from home care to other long-term care facilities.[27][33]
Advanced
During the final stages, the patient is completely dependent upon caregivers.[27] Language is reduced to simple phrases or even single words, eventually leading to complete loss of speech.[27][31] Despite the loss of verbal language abilities, people can often understand and return emotional signals. Although aggressiveness can still be present, extreme apathy and exhaustion are much more common symptoms. People with Alzheimer's disease will ultimately not be able to perform even the simplest tasks independently; muscle mass and mobility deteriorate to the point where they are bedridden and unable to feed themselves. The cause of death is usually an external factor, such as infection of pressure ulcers or pneumonia, not the disease itself.[27]
e. It's easy.
16 TICK BORNE DISEASES 16 SQUARES QMR
https://en.wikipedia.org/wiki/Tick-borne_disease
Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites. Tick-borne illnesses are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. Because individual ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment. Currently (2016), there are 16 known tick-borne diseases of humans (four discovered since 2013).
The neural crest as a fourth germ layer and vertebrates as quadroblastic not triploblastic
Authors
Brian K. Hall
GYMNOSPERMS ARE SEAD BEARING PLANTS- THERE ARE FOUR PHYLA OF SEED BEARING PLANTS----- THE FOURTH IS DIFFERENT
Diversity of Gymnosperms
Modern gymnosperms are classified into four phyla. The first three (the Coniferophyta, Cycadophyta, and Gingkophyta) are similar in their production of secondary cambium (cells that generate the vascular system of the trunk or stem and are partially specialized for water transportation) and their pattern of seed development. However, these three phyla are not closely related phylogenetically to each other. The fourth phylum (the Gnetophyta) are considered the closest group to angiosperms because they produce true xylem tissue.
https://en.wikipedia.org/wiki/Tetraspore
Tetraspores are red algae spores produced by the tetrasporophytic (diploid) phase in the life history of algae in the Rhodophyta as a result of meiosis.[1] The name is derived from the 4 spores that form after this meiosis, the division is of three kinds: cruciate, zonate and tetrahedral.[1]
TETRADS- TETRA MEANS FOUR
https://en.wikipedia.org/wiki/Evolutionary_history_of_plants
The first evidence of plants on land comes from spores of mid-Ordovician age (early Llanvirn, ~470 million years ago).[17][18][19] These spores, known as cryptospores, were produced either singly (monads), in pairs (dyads) or groups of four (tetrads), and their microstructure resembles that of modern liverwort spores, suggesting they share an equivalent grade of organisation.[7] Their walls contain sporopollenin – further evidence of an embryophytic affinity.[20] It could be that atmospheric 'poisoning' prevented eukaryotes from colonising the land prior to this,[21] or it could simply have taken a great time for the necessary complexity to evolve.[22]
Trilete spores similar to those of vascular plants appear soon afterwards, in Upper Ordovician rocks.[23] Depending exactly when the tetrad splits, each of the four spores may bear a "trilete mark", a Y-shape, reflecting the points at which each cell squashed up against its neighbours.[17] However, this requires that the spore walls be sturdy and resistant at an early stage. This resistance is closely associated with having a desiccation-resistant outer wall—a trait only of use when spores must survive out of water. Indeed, even those embryophytes that have returned to the water lack a resistant wall, thus don't bear trilete marks.[17] A close examination of algal spores shows that none have trilete spores, either because their walls are not resistant enough, or in those rare cases where it is, the spores disperse before they are squashed enough to develop the mark, or don't fit into a tetrahedral tetrad.[17]
FOUR SPORES FOUR POLLEN SACS
https://en.wikipedia.org/wiki/Sporogenesis
In meiotic sporogenesis, a diploid spore mother cell within the sporangium undergoes meiosis, producing a tetrad of haploid spores. In organisms that are heterosporous, two types of spores occur: Microsporangia produce male microspores, and megasporangia produce female megaspores. In megasporogenesis, often three of the four spores degenerate after meiosis, whereas in microsporogenesis all four microspores survive.
In gymnosperms, such as conifers, microspores are produced through meiosis from microsporocytes in microstrobili or male cones. In flowering plants, microspores are produced in the anthers of flowers. Each anther contains four pollen sacs, which contain the microsporocytes. After meiosis, each microspore undergoes mitotic cell division, giving rise to multicellular pollen grains (six nuclei in gymnosperms, three nuclei in flowering plants).
Megasporogenesis occurs in megastrobili in conifers (for example a pine cone) and inside the ovule in the flowers of flowering plants. A megasporocyte inside a megasporangium or ovule undergoes meiosis, producing four megaspores. Only one is a functional megaspore whereas the others stay dysfunctional or degenerate. The megaspore undergoes several mitotic divisions to develop into a female gametophyte (for example the seven-cell/eight-nuclei embryo sac in flowering plants).
QUAD IS FOUR
https://en.wikipedia.org/wiki/Melipona_quadrifasciata
Melipona quadrifasciata is a species of eusocial, stingless bee of the order Hymenoptera
TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetragonisca_angustula
Tetragonisca angustula is a small eusocial stingless bee found in Central and South America
https://en.wikipedia.org/wiki/Alcoholism
Johnson's typologies
Johnson (1980) explores the emotional progression of the addict’s response to alcohol. He looks at this in four phases. The first two are considered "normal" drinking and the last two are viewed as "typical" alcoholic drinking.[99][100] Johnson's four phases consist of:
Learning the mood swing. A person is introduced to alcohol (in some cultures this can happen at a relatively young age), and the person enjoys the happy feeling it produces. At this stage, there is no emotional cost.
Seeking the mood swing. A person will drink to regain that feeling of euphoria experienced in phase 1; the drinking will increase as more intoxication is required to achieve the same effect. Again at this stage, there are no significant consequences.
At the third stage there are physical and social consequences, i.e., hangovers, family problems, work problems, etc. A person will continue to drink excessively, disregarding the problems.
The fourth stage can be detrimental, as Johnson cites it as a risk for premature death. As a person now drinks to feel normal, they block out the feelings of overwhelming guilt, remorse, anxiety, and shame they experience when sober.[101]
FOUR SUBGENERA- MAKE PENICILIN
https://en.wikipedia.org/wiki/Penicillium
In a 1979 monograph, John I. Pitt divided Penicillium into four subgenera based on conidiophore morphology and branching pattern: Aspergilloides, Biverticillium, Furcatum, and Penicillium.[6]
Pfizer's S. aureus four-antigen vaccine SA4Ag was granted fast track designation by the U.S. Food and Drug Administration in February 2014.[92] In 2015, Pfizer has commenced a phase 2b trial regarding the SA4Ag vaccine.[93]
https://en.wikipedia.org/wiki/Staphylococcus_aureus
Novartis Vaccines and Diagnostics, a former division of Novartis and now part of GlaxoSmithKline, published in 2015 promising pre-clinical results of their four-component Staphylococcus aureus vaccine, 4C-staph.[94]
STEROIDS HAVE FOUR RINGS THE FOURTH IS DIFFERENT
https://simple.wikipedia.org/wiki/Steroid
A steroid is a organic compound, either natural or man-made, which has four cycloalkane rings in its structure.
Steroid hormones are steroids which act as hormones in the body. Natural steroid hormones are usually made from cholesterol in the adrenal glands and gonads. Cholesterol is a plentiful steroid in animal cells: it is important for cell membranes.
Examples of steroid hormones include
estrogen,
testosterone,
progesterone,
Vitamin D3 or cholecalciferol.
THE ROTATOR CUFF IS FOUR TENDONS
https://en.wikipedia.org/wiki/Shoulder_problem
Rotator cuff tear[edit]
Main article: Rotator cuff tear
The term "rotator cuff" refers to a group of four tendons that blend together as they attach to the upper end of the arm bone (humerus).
FOUR OF THEM
https://en.wikipedia.org/wiki/ErbB
The ErbB family of proteins contains four receptor tyrosine kinases, structurally related to the epidermal growth factor receptor (EGFR), its first discovered member. In humans, the family includes Her1 (EGFR, ErbB1), Her2 (Neu, ErbB2), Her3 (ErbB3), and Her4 (ErbB4). The gene symbol, ErbB, is derived from the name of a viral oncogene to which these receptors are homologous: erythroblastic leukemia viral oncogene. Insufficient ErbB signaling in humans is associated with the development of neurodegenerative diseases, such as multiple sclerosis and Alzheimer's Disease,[1] while excessive ErbB signaling is associated with the development of a wide variety of types of solid tumor.[2]
The ErbB protein family consists of 4 members
ErbB-1, also named epidermal growth factor receptor (EGFR)
ErbB-2, also named HER2 in humans and neu in rodents
ErbB-3, also named HER3
ErbB-4, also named HER4
v-ErbBs are homologous to EGFR, but lack sequences within the ligand binding ectodomain.
http://wiki.eyewire.org/index.php?title=Horizontal_Cell
I LEARNED ABOUT THESE FOUR TYPES IN BIOLOGY CLASS AND THE WAY THE PROFESSOR PRESENTED THEM AT UCSD THE FOURTH WAS DIFFERENT WITH THE FIRST THREE CLOSE TOGETHER AND THE FOURTH DIFFERENT
The four types of retinal neurons are bipolar cells, ganglion cells, horizontal cells, and amacrine cells.
https://en.wikipedia.org/wiki/Esophagus
The esophagus has four points of constriction. When a corrosive substance, or a solid object is swallowed, it is most likely to lodge and damage one of these four points. These constrictions arise from particular structures that compress the esophagus. These constrictions are:[7]
At the start of the esophagus, where the laryngopharynx joins the esophagus, behind the cricoid cartilage
Where it is crossed on the front by the aortic arch in the superior mediastinum
Where the esophagus is compressed by the left main bronchus in the posterior mediastinum
The esophageal hiatus where it passes through the diaphragm in the posterior mediastinum
FOUR SUBUNITES TETRAMERS
https://en.wikipedia.org/wiki/G_protein-gated_ion_channel
Four G protein gated inwardly-rectifying potassium (GIRK) channel subunits have been identified in mammals: GIRK1, GIRK2, GIRK3, and GIRK4. The GIRK subunits come together to form GIRK ion channels. These ion channels, once activated, allow for the flow of potassium ions (K+) from the extracellular space surrounding the cell across the plasma membrane and into the cytoplasm. Each channel consists of domains which span the plasma membrane, forming the K+-selective pore region through which the K+ ions will flow.[5][6] Both the N-and C-terminal ends of the GIRK channels are located within the cytoplasm. These domains interact directly with the βγ-complex of the G protein, leading to activation of the K+ channel. The GIRK ion channel family is the only group of G protein-gated ion channels which is known to directly interact with G proteins.[7] These domains on the N-and C-terminal ends which interact with the G proteins contain certain residues which are critical for the proper activation of the GIRK channel. In GIRK4, the N-terminal residue is His-64 and the C-terminal residue is Leu-268; in GIRK1 they are His-57 and Leu-262, respectively. Mutations in these domains lead to the channel's desensitivity to the βγ-complex and therefore reduce the activation of the GIRK channel.[3]
The four GIRK subunits are 80-90% similar in their pore-forming and transmembrane domains, a feature accountable by the similarities in their structures and sequences. GIRK2, GIRK3, and GIRK4 share an overall identity of 62% with each other, while GIRK1 only shares 44% identity with the others.[6] Because of their similarity, the GIRK channel subunits can come together easily to form heteromultimers (a protein with two or more different polypeptide chains). GIRK1, GIRK2, and GIRK3 show abundant and overlapping distribution in the central nervous system (CNS) while GIRK1 and GIRK4 are found primarily in the heart.[4] GIRK1 combines with GIRK2 in the CNS and GIRK4 in the atrium to form heterotetramers; each final heterotetramer contains two GIRK1 subunits and two GIRK2 or GIRK4 subunits. GIRK2 subunits can also form homotetramers in the brain, while GIRK4 subunits can form homotetramers in the heart.[7] GIRK1 subunits have not been shown to be able to form functional homotetramers. Though GIRK3 subunits are found in the CNS, their role in forming functional ion channels is still unknown.[4]
BACTERIAL GROWTH FOUR PHASES
https://en.wikipedia.org/wiki/Bacteria
Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced.[106] The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport.[107] The final phase is the death phase where the bacteria run out of nutrients and die.
FOUR BASIC MOTIONS
https://en.wikipedia.org/wiki/Forehead
The muscles of the forehead help to form facial expressions. There are four basic motions, which can occur individually or in combination to form different expressions. The occipitofrontalis muscles can raise the eyebrows, either together or individually, forming expressions of surprise and quizzicality. The corrugator supercilii muscles can pull the eyebrows inwards and down, forming a frown. The procerus muscles can pull down the centre portions of the eyebrows.[6]
FOUR SPECIES FOUR STRIPES
https://en.wikipedia.org/wiki/Rhabdomys
Rhabdomys is a largely Southern African genus of muroid rodents slightly larger than house mice. They are known variously as striped or four-striped mice or rats. Traditionally the genus has been seen as a single species, Rhabdomys pumilio, though modern evidence on the basis of karyotype and mtDNA analysis suggests that it comprises two or more species and subspecies.[1] Dorsally Rhabdomys species display four characteristic black longitudinal stripes on a paler background.[2]
DNA analyses support the existence of at least four distinct species
FOUR BLACK TIGER STRIPES EACH WING
https://en.wikipedia.org/wiki/Papilio_glaucus
.P glaucus has a wingspan measuring 7.9 to 14 cm (3.1 to 5.5 in). The male is yellow with four black "tiger stripes" on each forewing.
https://en.wikipedia.org/wiki/Fourspot_butterflyfish
The Four-spotted Butterflyfish or fourspot butterflyfish (Chaetodon quadrimaculatus) is a species of butterflyfish (family Chaetodontidae) found in the Pacific Ocean from the Ryukyus, Ogasawara (Bonin) Islands and Taiwan to the Hawaiian, Marquesan, and Pitcairn islands, south to the Samoan and Austral Islands and the Marianas and Marshall Islands in Micronesia.[1]
FOUR GROUPS WITH FOUR SPOTS
https://en.wikipedia.org/wiki/Painted_lady
The Cynthia group of colourful butterflies, commonly called painted ladies, comprises a subgenus of the genus Vanessa in the family Nymphalidae. They are well known throughout most of the world.
The group includes:
Painted lady (Vanessa cardui), which is almost global in its distribution
Australian painted lady (Vanessa kershawi)
American (painted) lady (Vanessa virginiensis)
West Coast lady (Vanessa annabella).
Contents [hide]
1 Distinguishing features
2 Lifespan
3 Comparison
4 References
5 External links
Distinguishing features[edit]
For a key to the terms used, see Glossary of entomology terms.
The painted lady (V. cardui) is a large butterfly (wing span 5–9 cm (2.0–3.5 in)) identified by the black and white corners of its mainly deep orange, black-spotted wings. It has five white spots in the black forewing tips and while the orange areas may be pale here and there, there are no clean white dots in them. The hindwings carry four small submarginal eyespots on the dorsal and ventral sides. Those on the dorsal side are black, but in the summer morph sometimes small blue pupils are present.
The American painted lady (V. virginiensis) is most easily distinguishable by its two large hindwing eyespots on the ventral side. V. virginiensis also features a white dot within the subapical field of the forewings set in pink on the ventral side, and often as a smaller clean white dot in the orange of the dorsal side too. A less reliable indicator is the row of eyespots on the dorsal submarginal hindwing; V. virginiensis often has two larger outer spots with blue pupils. The black forewing tips have four to five white spots; usually the largest is whitish orange.
The West Coast lady (V. annabella) does not have obvious ventral eyespots. On the dorsal side, V. anabella lacks a white dot in the subapical orange found in V. virginiensis, and is a purer orange color. V. annabella has a fully orange subapical band and leading edge on the forewing. The submarginal row of hindwing spots in V. annabella features three or four blue pupils. The two larger pupils in V. annabella are the inner spots, rather than the outer spots as in corresponding V. virginiensis.
The Australian painted lady (V. kershawi) is quite similar to V. cardui. Its four ventral eyespots are less clearly defined, and it always sports at least three (often four) blue pupil spots on its dorsal hindwing. Caterpillars are found mainly on Ammobium alatum.
TETRAMER FOUR CLASSES- FOUR ISOFORMS
https://en.wikipedia.org/wiki/Lactate_dehydrogenase
LDH exist in four distinct enzyme classes. This article is specifically about the NAD(P)-dependent L-lactate dehydrogenase. Other LDHs act on D-lactate and/or are dependent on cytochrome c: D-lactate dehydrogenase (cytochrome)) and L-lactate (L-lactate dehydrogenase (cytochrome)).
Lactate dehydrogenase is composed of four subunits (tetramer). The two most common subunits are the LDH-M and LDH-H protein, encoded by the LDHA and LDHB genes, respectively. These two subunits can form five possible tetramers (isoenzymes): 4H, 4M, and the three mixed tetramers (3H1M, 2H2M, 1H3M). These five isoforms are enzymatically similar but show different tissue distribution: The major isoenzymes of skeletal muscle and liver, M4, has four muscle (M) subunits, while H4 is the main isoenzymes for heart muscle in most species, containing four heart (H) subunits.
The M and H subunits are encoded by two different genes:
The M subunit is encoded by LDHA, located on chromosome 11p15.4 (Online Mendelian Inheritance in Man (OMIM) 150000)
The H subunit is encoded by LDHB, located on chromosome 12p12.2-p12.1 (Online Mendelian Inheritance in Man (OMIM) 150100)
A third isoform, LDHC or LDHX, is expressed only in the testis (Online Mendelian Inheritance in Man (OMIM) 150150); its gene is likely a duplicate of LDHA and is also located on the eleventh chromosome (11p15.5-p15.3)
The fourth isoform is localized in the peroxisome. It is tetramer containing one LDHBx subunit, which is also encoded by LDHB gene. The LDHBx protein is seven amino acids longer than the LDHB (LDH-H) protein. This amino acid extension is generated by functional translational readthrough.[4]
A complete lactate dehydrogenase enzyme consists of four protein subunits.[
FOUR COMPLEXES
https://en.wikipedia.org/wiki/Homeotic_selector_gene
Homologs of the Homeotic selector gene are found in a variety of species, varying from cnidarians to nematodes, to mammals. These genes are grouped similarly to the Hox complex found in insects. The mouse has four complexes, HoxA, HoxB, HoxC, and HoxD, each on different chromosomes. Individual genes in each complex correspond to specific members of the Drosophila genome. The mammalian Hox genes can function in Drosophila as partial replacements for the Drosophila Hox genes. Each of the four mammalian Hox complexes has a rough counterpart in the insect complex.
The theory behind this evolutionary conservation stems from the belief that some common ancestor of worms, flies, and vertebrates had a single primordial homeotic selector gene, an ancestral Hox complex, that went through repeated duplication to form a series of tandem genes. In Drosophila, this ancestral Hox complex split into two separate complexes: Antennapedia and Bithorax. In mammals, the whole complex repeatedly duplicated resulting in four Hox complexes. This theory has some faults, including that some individual genes have been duplicated while others have been lost.[6]
Changes in homeotic gene expression contributes to the diversity. The Drosophila genome holds its eight homeotic genes in two complexes. The Invertebrate genome contains 8-10 of is homeotic genes in only one complex, while Vertebrates have duplicated the Hox complex and have four clusters.
https://en.wikipedia.org/wiki/J._B._S._Haldane
"I suppose the process of acceptance will pass through the usual four stages: i) This is worthless nonsense, ii) This is an interesting, but perverse, point of view, iii) This is true, but quite unimportant, iv) I always said so."[71]
FOUR CLUMPS OF HAIR
https://en.wikipedia.org/wiki/Orgyia_antiqua
O. antiqua caterpillar showing the four clumps of yellow tussock hairs on its back
The larvae hatch early in the spring, as soon as foliage starts to appear.[5] They are easily recognized by their horn-like tufts of hair-like setae. Four toothbrush-like tufts occur along the back, and hair pencils project from the sides at the front and at the back. The body is dark grey to black, and red tubercules are along the sides and back.
https://en.wikipedia.org/wiki/Motor_cortex
The premotor cortex is now generally divided into four sections.[11][12][13] First it is divided into an upper (or dorsal) premotor cortex and a lower (or ventral) premotor cortex. Each of these is further divided into a region more toward the front of the brain (rostral premotor cortex) and a region more toward the back (caudal premotor cortex). A set of acronyms are commonly used: PMDr (premotor dorsal, rostral), PMDc, PMVr, PMVc. Some researchers use a different terminology. Field 7 or F7 denotes PMDr; F2 = PMDc; F5=PMVr; F4=PMVc.
FOUR SUBDIVISIONS OF CINGULATE CORTEX- ANTERIOR CINGULATE DIVIDED INTO FOUR
http://www.sicotests.com/psyarticle.asp?id=263
The anterior cingulate cortex is located towards the front of the cingulate cortex--a region that circles above the corpus callosum (Gabriel, Burhans, Talk, && Scalf, 2002). This region is connected to the prefrontal cortex and parietal cortex as well as both motor and visual systems. Furthermore, the anterior cingulate cortex is one of the four main subdivisions of the cingulate cortex. The other subdivisions are the posterior cingulate cortex, the mid cingulate cortex, and the retrosplenial anterior cingulate cortex.
The anterior cingulate cortex is sometimes divided into four regions, each of which seem to underpin a separate function (see Bush, Luu, && Posner, 2000). In particular, the anterior cingulate cortex includes:
The anterior region, which is involved in executive function
The dorsal region, which is involved in cognitive processes
The ventral region, which is involved in emotional regulation
The posterior region, which is involved in evaluative processes (e.g., Bush, Vogt, Holmes, Dale, Greve, Jenike et al., 2002)
THE SUPER 16 STRAND
https://en.wikipedia.org/wiki/Scoubidou
Large stitches[edit]
A sixteen-stranded scoubidou
Many scoubidou stitches which are commonly done with small numbers of strands can be generalized to use any number of strands. The Super-16 is a large scoubidou consisting of sixteen strands woven together. The Super-16 can be compared to the Square stitch but on a much larger scale.[12]
IN STITCHING YOU MAKE QUADRANTS
https://en.wikipedia.org/wiki/Celtic_cross_stitch
Celtic cross stitch is a style of cross-stitch embroidery which recreates Celtic art patterns typical of early medieval Insular art using contemporary cross-stitch techniques. Celtic cross stitch typically employs rich, deep colors, intricate geometrical patterns, spirals, interlacing patterns, knotwork, alphabets, animal forms and zoomorphic patterns, similar to the decorations found in the Book of Kells.
THERE ARE 16 ORDERS OF MILLIPEDE
https://en.wikipedia.org/wiki/Millipede
Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name being derived from this feature. Each double-legged segment is a result of two single segments fused together. Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments, while pill millipedes are shorter and can roll into a ball. Although the name "millipede" derives from the Latin for "thousand feet", no known species has 1,000; the record of 750 legs belongs to Illacme plenipes. There are approximately 12,000 named species classified into 16 orders and around 140 families, making Diplopoda the largest class of myriapods, an arthropod group which also includes centipedes and other multi-legged creatures.
EIGHT PAIRS OF LEGS THAT IS 16 LEGS
https://en.wikipedia.org/wiki/Hallucigenia
Hallucigenia is a 0.5—3.5 cm long tubular organism with seven or eight pairs of slender legs, each terminating with a pair of claws. Above each leg is a rigid conical spine. The 'head' and 'tail' end of the organism are difficult to identify; one end extends some distance beyond the legs and often droops down as if to reach the substrate. Although some specimens display traces of a gut, the internal anatomy has not been formally described. Recent research suggests that the extended element is an elongated head with two simple eyes, a mouth with radial teeth, and pharyngeal teeth within the front of the gut.[4][5]
FOUR RED SPOTS CALLED QUAD
https://www.theguardian.com/environment/gallery/2013/jul/22/ladybird-species-harlequin-uk-insects
The pine ladybird ( Exochomus qadripustulatus) is round in shape with a pronounced rim around the margin of the wing cases. It is black with between two and four red spots; the spots at the outer front margin of the wing cases are comma-shaped. Inhabits needled conifers, sallows and willows, and overwinters in leaf litter, foliage and bark crevices of evergreen trees and shrubs
FOUR GENERA
https://en.wikipedia.org/wiki/Cryptopidae
The Cryptopidae are a family of scolopendromorph centipedes. Cryptopids are blind (lacking ocelli) and possess 21 pairs of legs as adults.[1] The genus Cryptops is the numerically largest in the family, comprising over 150 species worldwide.[2]
Classification[edit]
The four genera, with at least 184 species, are:[3]
Cryptops Leach, 1815
Paracryptops Pocock, 1891
Tonkinodentus Schileyko, 1992
Trigonocryptops Verhoeff, 1906
https://en.wikipedia.org/wiki/Orthoptera
Among the four subfamilies of Tettigoniidae, the relationships are (Phaneropterinae + (Conocephalinae + (Bradyporinae + Tettigoniinae))
FOUR BARS ON TAIL
https://en.wikipedia.org/wiki/Black_hawk-eagle
The black hawk-eagle is 58–70 cm (23–28 in) long and weighs about 900-1,300 grams (2-2.9 lbs). It has black plumage with varying patterns on its wings and body, and white speckling in places. It has barred wings, slightly elliptical in shape, and a long, narrow tail which is rarely fanned. The four grey bars on the tail are distinctive to the black hawk-eagle, as is the white line seen slightly above the bird's eye. While flying, the broadness and shortness of the wings become apparent.[5] While in flight, the bird's tail is typically kept closed.[3][4]
CREST OF FOUR FEATHERS
https://en.wikipedia.org/wiki/Changeable_hawk-eagle
Normally brown above, they have white below with barring on the undersides of the flight feathers and tail; black longitudinal streaks occur on the throat and chocolate streaks occur on the breast. Some subspecies have a crest of four feathers, but this is all but absent in others. The sexes are quite similar in their plumage, but males are about 15% smaller than females.[4] The underparts and head of juveniles are whitish or buff with few dark streaks.[4]
FOURTH SPECIES IS DIFFERENT
https://en.wikipedia.org/wiki/Thresher_shark
Thresher sharks are large lamniform sharks of the family Alopiidae found in all temperate and tropical oceans of the world; the family contains four species, all within the genus Alopias.
The three extant thresher shark species are all in the genus Alopias. The possible existence of a hitherto unrecognized fourth species was revealed during the course of a 1995 allozyme analysis by Blaise Eitner. This species is apparently found in the eastern Pacific off Baja California, and has previously been misidentified as the bigeye thresher. So far, it is only known from muscle samples from one specimen, and no aspect of its morphology has been documented.[3]
Alopias pelagicus H. Nakamura, 1935 (Pelagic thresher)
Alopias superciliosus R. T. Lowe, 1841 (Bigeye thresher)
Alopias vulpinus Bonnaterre, 1788 (Common thresher)
FOUR SPECIES CAUSE MALARIA HUMANS
https://en.wikipedia.org/wiki/Parasitology
Plasmodium spp., the protozoan parasite which causes malaria. The four species of malaria parasites infective to humans are Plasmodium falciparum,Plasmodium malariae, Plasmodium vivax & Plasmodium ovale.
four families
https://en.wikipedia.org/wiki/Bull_shark
The bull shark is the best known of 43 species of elasmobranch in 10 genera and four families to have been reported in fresh water.[26] Other species that enter rivers include the stingrays (Dasyatidae, Potamotrygonidae and others) and sawfish (Pristidae). Some skates (Rajidae), smooth dogfishes (Triakidae), and sandbar sharks (Carcharhinus plumbeus) regularly enter estuaries.[citation needed]
FOUR FAMILIES
https://en.wikipedia.org/wiki/Whale
Mysticetes are also known as baleen whales. They have a pair of blowholes side-by-side and lack teeth, which renders them incapable of catching larger prey; they instead have baleen plates which is a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton and other food from the water; this forces them to follow krill or plankton migrations. Some whales, such as the humpback, reside in the polar regions where they feed on a reliable source of schooling fish and krill.[7] These animals rely on their well-developed flippers and tail fin to propel themselves through the water; they swim by moving their fore-flippers and tail fin up and down. Whale ribs loosely articulate with their thoracic vertebrae at the proximal end, but do not form a rigid rib cage. This adaptation allows the chest to compress during deep dives as the pressure increases.[8] Mysticetes consist of four families: rorquals (balaenopterids), cetotheriids, right whales (balaenids), and grey whales (eschrichtiids).
A study done by Doetsch (1999) showed that astrocytes in the SVZ can be dedifferentiate and differentiate into neurons in the olfactory bulb. Among four types of cells in the SVZ (migrating neuroblasts, immature precursors, astrocytes, and ependymal cells), migrating neuroblasts and immature precursors are silenced with the anti-mitotic agent and astrocytes are infected with a retrovirus. In the result, neurons that have the retrovirus are found in the olfactory bulb.[13]
Beginning April 5, 2010, fluoxetine became one of four antidepressant drugs that the FAA permitted for pilots with authorization from an aviation medical examiner. The other permitted antidepressants are sertraline (Zoloft), citalopram (Celexa), and escitalopram (Lexapro).[103] These four remain the only antidepressants permitted by FAA as of 2 December 2016 https://en.wikipedia.org/wiki/Fluoxetine
from wiki
The fourth is always transcendent
https://en.wikipedia.org/wiki/Domain_(biology)
None of the three systems currently include non-cellular life. As of 2011 there is talk about Nucleocytoplasmic large DNA viruses possibly being a fourth branch domain of life, a view supported by researchers in 2012.[6]
https://en.wikipedia.org/wiki/Chloroplast
Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes.[16] Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.[14]
http://www.quit.org.au/reasons-to-quit/health-risks-of-smoking/16-cancers
The '16 cancers' campaign highlights the fact that smoking causes a range of cancers including liver, bowel, kidney, cervical and ovarian, and that you have one clear way to reduce your risk by quitting today.
https://en.wikipedia.org/wiki/The_Canon_of_Medicine
This is in one of my books
Avicenna begins part one by dividing theoretical medicine and medical practice. He describes what he says are the "four causes" of illness, based on Aristotelian philosophy: The material cause, the efficient cause, the formal cause, and the final cause:[8]:29–31
Material Cause Avicenna says that this cause is the human subject itself, the "members or the breath" or "the humours" indirectly.
Efficient Cause The efficient cause is broken up into two categories: The first is "Extrinsic", or the sources external to the human body such as air or the region we live in. The second efficient cause is the "Intrinsic", or the internal sources such as our sleep and "its opposite-the waking state", the "different periods of life", habits, and race.
Formal Cause The formal cause is what Avicenna called "the constitutions ; the compositions". According to Oskar Cameron Gruner, who provides a treatise within Avicenna's Canon of Medicine, this was in agreement with Galen who believed that the formal cause of illness is based upon the individual's temperament.
Final Cause The final cause is given as "the actions or functions".
Thesis II The Elements of Cosmology[edit]
Avicenna's thesis on the elements of the cosmos is described by Gruner as "the foundation of the whole Canon".[8]:39 Avicenna insists here that a physician must assume the four elements that are described by natural philosophy,[8]:34 although Avicenna makes it clear that he distinguishes between the "simple" element, not mixed with anything else, and what we actually experience as water or air, such as the sea or the atmosphere. The elements we experience are mixed with small amounts of other elements and are therefore not the pure elemental substances.[8]:202 The "light" elements are fire and air, while the "heavy" are earth and water:
The Earth Avicenna upholds Aristotelian philosophy by describing Earth as an element that is geocentric. The Earth is at rest, and other things tend towards it because of its intrinsic weight. It is cold and dry.[8]:35
The Water Water is described as being exterior to the sphere of the Earth and interior to the sphere of the Air, because of its relative density. It is cold and moist. "Being moist, shapes can be readily fashioned (with it), and as easily lost (and resolved)."[8]:35
The Air The position of Air above Water and beneath Fire is "due to its relative lightness". It is "hot and moist", and its effect is to "rarefy" and make things "softer".[8]:36
The (sphere of the) Fire Fire is higher than the other elements, "for it reaches to the world of the heavens". It is hot and dry; it traverses the substance of the air, and subdues the coldness of the two heavy elements; "by this power it brings the elementary properties into harmony."[8]:37
Thesis III The Temperaments[edit]
The Canon of Medicine divides the thesis on temperaments into three subsections; a general overview, one based on members of the body, and temperaments based on age.
I The Temperaments (General description)[edit]
The temperaments are reported to be the interaction between the four different element's qualities, such as the conflict between dryness, wetness, cold, and hot. Avicenna suggests that these qualities battle between each other until an equilibrium state is reached and this state is known as the temperaments.[8]:57–65
The Canon also adopted the ancient theory of Four Temperaments and extended it to encompass "emotional aspects, mental capacity, moral attitudes, self-awareness, movements and dreams." This expanded theory of four temperaments is given in the following table:[10]
Evidences of the four primary temperaments
Evidence Hot Cold Moist Dry
Morbid states Inflammations become febrile
Loss of vigour Fevers related to serous humour
Rheumatism Lassitude
Functional power Deficient energy Deficient digestive power Difficult digestion
Subjective sensations Bitter taste
Excessive thirst
Burning cardiac orifice Lack of desire for fluids Mucoid salivation
Sleepiness Insomnia, wakefulness
Physical signs High pulse rate,
approaching lassitude Flaccid joints Diarrhea
Swollen eyelids Rough skin
Acquired habit
Foods & medicines Calefacients harmful Infrigidants harmful Moist aliments harmful Dry regimen harmful
Infrigidants beneficial Calefacients beneficial Humectants beneficial
Relation to weather Worse in summer Worse in winter Bad in autumn
The Eight Varieties of Equipoise
Canon describes humans as having eight different "varieties of equipoise", or differing temperaments.[8]:59 The temperaments fall under two categories; In relation to beings other than men and in relation to the individual himself.
A. In relation to beings other than men
i. "the equability of the temperament seen in man as compared with other creatures"
ii. the temperament of other human beings
Avicenna describes a hot versus cold / moist versus dry equilibrium between the members of the human body. The heart, for example, is hot and must be in equilibrium of other cold parts of the body such as the brain. When this equilibrium between these members are achieved, the person is considered to be in "ideal equability." [8]:59–60
iii. external factors "such as race, climate, atmosphere"
This third gauge for temperament assumes that each race has their own equilibrium. As an example he says, "The Hindus, in health, have a different equability to the Slaves, and so on." Avicenna explains that the differing climates contribute to differing temperaments among the races.[8]:60
iv. in relation to extreme climates
B. In relation to the individual himself
v. "as compared to another person"
Although Avicenna had listed the fifth mode "as compared to another person", he seems to contradict that statement by explaining that every individual has a temperament that is unique to themselves and unlike anyone else.[8]:59–61
vi. comparison of the individual himself
vii. comparing one member of the body with another member of the body
The Canon here makes the distinction of the members into categories of their individual "moistness", "dryness", "hotness", and "coldness".
viii. comparison of a member to itself
The Canon continues to explain the sun's position in relation to ideal temperament and the role that climate and human skin play. Organs are nowhere near ideal in temperament, but skin comes the closest. Avicenna says that the hand, especially the palm and the tip of the index finger, is the most sensitive of all and attuned to tactile contact. Medicine is described as "hot" or "cold", not based upon its actual temperature but with regard to how it relates to the temperament of the human body.[8]:62–63
The Canon then describes when temperaments are unequal, in other words, illness. Avicenna separates these into two categories, which are fairly self explainable within the context of what he had already defined as the temperaments.
A. Simple "intemperaments"[8]:63
Hot temperament (hotter than normal)
Cold temperament (colder than normal)
Dry temperament (drier than usual)
Moist temperament (more moist than usual)
B. Compound "intemperaments"
The compound intemperaments are where two things are wrong with the temperament, i.e. hotter and moister; hotter and drier; colder and moister; colder and drier. There are only four because something cannot be simultaneously hotter and colder or drier and moister. The four simple temperaments and four compound intemperaments can each be divided into "Those apart from any material substance" and "Those in which some material substance is concerned", for a total of sixteen intemperaments. Examples of the sixteen intemperaments are provided in the "third and fourth volumes."[8]:64
II The Temperament of the Several Members[edit]
Each member of the body is described to be given each its individual temperament, each with its own degree of heat and moisture. Avicenna lists members of the body in "order of degree of Heat", from hottest to coldest.[8]:66
the breath and "the heart in which it arises"
the blood; which is said to be generated from the liver
the liver; "which may be looked upon as concentrated blood."
the flesh
the muscles
the spleen
the kidneys
the arteries
the veins
the skin of the palms and soles
Then a list is given of coldest members to hottest.[8]:66
serious humour
the hairs
the bones
the cartilage
the ligaments
the tendon
the membranes
the nerves
the spinal cord
the brain
the fat
the oil of the body
the skin
Then a list is given in order of moisture. Avicenna credits Galen with this particular list.[8]:67
serious humour
the serious humour
the blood
the oil
the fat
the brain
the spinal cord
the breasts and the testicles
the lung
the liver
the spleen
the kidneys
the muscles
the skin
Finally, a list is given in order of dryness<[8]:67–68
the hair
the bone
cartilage
ligaments
tendons
sereous membranes
arteries
veins
motor nerves
heart
sensory nerves
skin
III The Temperaments Belonging to Age[edit]
The Canon divides life into four "periods" and then subdivides the first period into five separate categories.
The following table is provided for the four periods of life:[8]:68
Period Title Name Year of Age
I The Period of Growth Adolescence Up to 30
II The Prime of Life Period of beauty Up to 35 or 40
III Elderly life Period of decline. Senescence. Up to about 60
IV Decrepit Age Senility To the end of life
Avicenna says that the third period shows signs of decline in vigor and some decline in intellectual power. In the fourth period, both vigor and intelligence decline.
Avicenna divides the beginning stage of life in the following table, according to Oskar Cameron Gruner's edition of the Canon of Medicine:[8]:69
Sub-division Name Distinctive Characters
First Infancy The period before the limbs are fitted for walking
Second Babyhood The period of formation of the teeth. Walking has been learnt, but is not steady. The gums are not full of teeth.
Third Childhood The body shows strength of movement. The teeth are fully out. Pollutions have not yet appeared
Fourth Juvenility. "Puberty" The period up to the development of hair on the face and pubes. Pollutions begin.
Fifth Youth The period up to the limit of growth of the body (to the beginning of adult life). Period of athletic power.
Avicenna generalizes youth as having a "hot" temperament, but comments that there is controversy over which periods of youth are hotter. The general notion that youth are "hot" in temperament is due to youth's supposed relationship to members of the body that are hot. For example, blood was considered "hot" as was mentioned earlier, therefore youth is assumed to be hot partially due to blood being more "plentiful" and "thicker", according to Avicenna. Evidence for youth having an excess of blood is suggested by Avicenna's observation that nose bleeds are more frequent within youth. Other contributing factors are the youth's association with sperm and the consistency of their bile. Further description of youth in regards to heat and moisture is given with respect to sex, geographical location, and occupation. The Canon says, for example, that females are colder and more moist.[8]:69–74
The Humours[edit]
The Canon of Medicine is based upon the Four Humours of Hippocratic medicine, but refined in various ways. In disease pathogenesis, for example, Avicenna "added his own view of different types of spirits (or vital life essences) and souls, whose disturbances might lead to bodily diseases because of a close association between them and such master organs as the brain and heart".[11] An element of such belief is apparent in the chapter of al-Lawa", which relates "the manifestations to an interruption of vital life essence to the brain." He combined his own view with that of the Four Humours to establish a new doctrine to explain the mechanisms of various diseases in another work he wrote, Treatise on Pulse:[citation needed]
“From mixture of the four [humors] in different weights, [God the most high] created different organs; one with more blood like muscle, one with more black bile like bone, one with more phlegm like brain, and one with more yellow bile like lung.
[God the most high] created the souls from the softness of humors; each soul has its own weight and amalgamation. The generation and nourishment of proper soul takes place in the heart; it resides in the heart and arteries, and is transmitted from the heart to the organs through the arteries. At first, it [proper soul] enters the master organs such as the brain, liver or reproductive organs; from there it goes to other organs while the nature of the soul is being modified in each [of them]. As long as [the soul] is in the heart, it is quite warm, with the nature of fire, and the softness of bile is dominant. Then, that part which goes to the brain to keep it vital and functioning, becomes colder and wetter, and in its composition the serous softness and phlegm vapor dominate. That part, which enters the liver to keep its vitality and functions, becomes softer, warmer and sensibly wet, and in its composition the softness of air and vapor of blood dominate.
In general, there are four types of proper spirit: One is brutal spirit residing in the heart and it is the origin of all spirits. Another – as physicians refer to it – is sensual spirit residing in the brain. The third – as physicians refer to it – is natural spirit residing in the liver. The fourth is generative – i.e. procreative – spirits residing in the gonads. These four spirits go-between the soul of absolute purity and the body of absolute impurity.”
https://en.wikipedia.org/wiki/File:Equal_vs_unequal_cleavage.jpg
https://en.wikipedia.org/wiki/Cleavage_(embryo)
D quadrant specification through equal and unequal cleavage mechanisms. At the 4-cell stage of equal cleavage, the D macromere has not been specified yet. It will be specified after the formation of the third quartet of micromeres. Unequal cleavage occurs in two ways: asymmetric positioning of the mitotic spindle, or through the formation of a polar lobe (PL).
https://en.wikipedia.org/wiki/Thyroid
The hormone T4 has four atoms of iodine, while T3 has three atoms of iodine. T4 and T3 regulate metabolism, growth, heart rate, body temperature, and affect protein synthesis. The hormone calcitonin is produced by thyroid parafollicular cells. Calcitonin helps to regulate calcium concentrations by lowering blood calcium levels when the levels are high.
Thyroid Hormone Regulation
Thyroid hormones T4 and T3 are regulated by the pituitary gland. This small endocrine gland is located in the middle of the base of the brain. It controls a multitude of important functions in the body. The pituitary gland is termed the "Master Gland" because it directs other organs and endocrine glands to suppress or induce hormone production. One of the many hormones produced by the pituitary gland is thyroid stimulating hormone (TSH). When levels of T4 and T3 are too low, TSH is secreted to stimulate the thyroid to produce more thyroid hormones. As levels of T4 and T3 rise and enter the blood stream, the pituitary senses the increase and reduces its production of TSH. This type of regulation is an example of a negative feedback mechanism. The pituitary gland is itself regulated by the hypothalamus. Blood vessel connections between the hypothalamus and pituitary gland allow hypothalamic hormones to control pituitary hormone secretion. The hypothalamus produces thyrotropin-releasing hormone (TRH). This hormone stimulates the pituitary to release TSH.
Thyroid Problems
When the thyroid gland is not functioning properly, several thyroid disorders may develop. These disorders can range from a slightly enlarged gland to thyroid cancer. An iodine deficiency may cause the thyroid to become enlarged. An enlarged thyroid gland is referred to as a goiter. When the thyroid produces hormones in excess of the normal amount, it causes a condition called hyperthyroidism. When the thyroid does not produce enough thyroid hormone, hypothyroidism occurs. Many instances of hyperthyroidism and hypothyroidism are caused by autoimmune thyroid diseases. In autoimmune disease, the immune system attacks the body's own normal tissues and cells. Autoimmune thyroid diseases can cause the thyroid to become overactive or to stop producing hormones entirely.
Parathyroid Glands
Parathyroid glands are four small tissue masses located on the posterior side of the thyroid. These glands vary in number, but typically two or more may be found in the thyroid. Parathyroid glands contain many cells that secrete hormones and have access to extensive blood capillary systems. Parathyroid glands produce and secrete parathyroid hormone. This hormone helps to regulate calcium concentrations by increasing blood calcium levels when these levels dip below normal. Parathyroid hormone counteracts calcitonin, which decreases blood calcium levels. Parathyroid hormone increases calcium levels by promoting the break down of bone to release calcium, by increasing calcium absorption in the digestive system, and by increasing calcium absorption by the kidneys. Calcium ion regulation is vital to the proper functioning of organ systems such as the nervous system and muscular system.
quadrant streak
a technique for microbial inoculation in which a single colony is isolated on a culture plate divided into four sections.
http://www.scienceclarified.com/Di-El/Ebola-Virus.html
Since that first outbreak in 1976, four subtypes or versions of the Ebola virus have been identified so far. The first three, called Ebola-Zaire, Ebola-Sudan, and Ebola-Ivory Coast, are known to have caused disease in humans. The fourth, called Ebola-Reston after the Reston, Virginia, primate laboratory where it was first discovered, seems to only be transmitted by monkeys to monkeys, although it may be the only one of the four viruses that is airborne (meaning it can be spread through particles floating in the air).
Read more:
Ebola Virus - humans, body, oxygen, air, cells, parts, part
The Ebola (pronounced ee-BO-luh) virus is the common name for a severe, often-fatal bleeding or hemorrhagic (pronounced hem-or-RAD-jik) fever that…
SCIENCECLARIFIED.COM
https://en.wikipedia.org/wiki/Cnidaria
Cnidarians were for a long time grouped with Ctenophores in the phylum Coelenterata, but increasing awareness of their differences caused them to be placed in separate phyla. Modern cnidarians are generally classified into four main classes:[9] sessile Anthozoa (sea anemones, corals, sea pens); swimming Scyphozoa (jellyfish) and Cubozoa (box jellies); and Hydrozoa, a diverse group that includes all the freshwater cnidarians as well as many marine forms, and has both sessile members such as Hydra and colonial swimmers such as the Portuguese Man o' War. Staurozoa have recently been recognised as a class in their own right rather than a sub-group of Scyphozoa, and the parasitic Myxozoa and Polypodiozoa are now recognized as highly derived cnidarians rather than more closely related to the bilaterians.[28]
Medusae and complex swimming colonies such as siphonophores and chondrophores sense tilt and acceleration by means of statocysts, chambers lined with hairs which detect the movements of internal mineral grains called statoliths. If the body tilts in the wrong direction, the animal rights itself by increasing the strength of the swimming movements on the side that is too low. Most species have ocelli ("simple eyes"), which can detect sources of light. However the agile Box Jellyfish are unique among Medusae because they possess four kinds of true eyes that have retinas, corneas and lenses.[23] Although the eyes probably do not form images, Cubozoa can clearly distinguish the direction from which light is coming as well as negotiate around solid-colored objects.[9][23]
http://rachelfriends.org:81/wikipedia_…/A/Cell_receptor.html
Type 1: L (ionotropic receptors)– These receptors are typically the targets of fast neurotransmitters such as acetylcholine (nicotinic) and GABA and activation of these receptor results in changes in ion movement across the membrane. They have a hetero structure. Each subunit consists of the extracellular ligand-binding domain and a transmembrane domain where the transmembrane domain in turn includes four transmembrane alpha helixes. The ligand binding cavities are located at the interface between the subunits.
http://rachelfriends.org:81/wikipedia_…/A/Cell_receptor.html
Type 1: L (ionotropic receptors)– These receptors are typically the targets of fast neurotransmitters such as acetylcholine (nicotinic) and GABA and activation of these receptor results in changes in ion movement across the membrane. They have a hetero structure. Each subunit consists of the extracellular ligand-binding domain and a transmembrane domain where the transmembrane domain in turn includes four transmembrane alpha helixes. The ligand binding cavities are located at the interface between the subunits.
http://rachelfriends.org:81/wikipedia_…/A/Cell_receptor.html
Structure
Transmembrane receptor:E=extracellular space; I=intracellular space; P=plasma membrane
The structures of receptors are very diverse and can broadly be classified into the following four categories:
Type 1: L (ionotropic-receptors)– These receptors are typically the targets of fast-neurotransmitters such as acetylcholine (nicotinic) and GABA; and, activation of these receptors results in changes in ion-movement across a membrane. They have a hetero-structure. Each subunit consists of the extracellular-ligand-binding domain and a transmembrane-domain where the transmembrane-domain in turn includes four transmembrane-alpha helixes. The ligand-binding cavities are located at the interface between the subunits.
Type 2: G protein-coupled receptors (metabotropic) – This is the largest family of receptors and includes the receptors for several hormones and slow transmitters e.g. dopamine, metabotropic-glutamate. They are composed of seven transmembrane-[alpha helix|alpha helices]]. The loops connecting the alpha-helices form extracellular and intracellular-domains. The binding-site for larger peptidic-ligands is usually located in the extracellular-domain whereas the binding-site for smaller non-peptidic ligands is often located between the seven alpha-helices and one extracellular-loop.[1] The aforementioned receptors are coupled to different intracellular-effector systems via G-proteins.[2]
Type 3: kinase linked and related receptors (see "Receptor tyrosine kinase", and "Enzyme-linked receptor") - They are composed of an extracellular-domain containing the ligand-binding site and an intracellular-domain, often with enzymatic-function, linked by a single transmembrane-alpha helix. e.g. the insulin-receptor.
Type 4: nuclear receptors – While they are called nuclear-receptors, they are actually located in the cytosol and migrate to the nucleus after binding with their ligands. They are composed of a C-terminal-ligand-binding region, a core-DNA-binding domain (DBD) and an N-terminal-domain that contains the AF1(activation function 1) region. The core-region has two zinc-fingers that are responsible for recognising the DNA-sequences specific to this receptor. The N-terminal interacts with other cellular-transcription factors in a ligand-independent manner; and, depending on these interactions it can modify the binding/activity of the receptor. Steroid and thyroid-hormone receptors are examples of such receptors.[3]
https://en.wikipedia.org/wiki/Quadrant_Shopping_Centre
The Quadrant Shopping Centre is the principal under-cover shopping centre in Swansea, Wales. The centre opened in 1979.[1] Since the 1980s it has been home to the Swansea Devil, a controversial carved wooden statue of the Devil.
The centre and surrounding areas are owned by the City and County of Swansea council.[2]
THESE ARE THE FOUR MAJOR DOPAMINE PATHWAYS- there are four minor
The Four Dopamine Pathways Relevant to Antipsychotics Pharmacology
By Flavio Guzmán, MD
This video describes the 4 dopamine pathways relevant to the mechanism of action and adverse effects of antipsychotic drugs.
Presentation outline:
There are 4 main dopamine pathways in the brain:
http://sketchymedicine.com/2012/01/dopamine-pathways-in-the-brain-and-schizophrenia/
Nigro-Striatal: substantial nigra to basal ganglia, involved in movement (what gets affected to cause EPS: tardive dyskinesia, akatisia)
Meso-Limbic: VTA to nucleus accumbens, “reward” pathway (causes the positive symptoms of schizophrenia)
Meso-Cortical: VTA to cortex, motivation and emotional response (thought to cause the negative symptoms of schizophrenia)
Tubulo-Infundibular: hypothalamus to posterior pituitary (hypoprolactinemia in untreated individuals, but D2 blockade with antipsychotics can cause a hyperprolactenemia)
https://en.wikipedia.org/wiki/Cell_junction
Proteins[edit]
There have been approximately 40 proteins identified to be involved in tight junctions. These proteins can be classified into four major categories; scaffolding proteins, signalling proteins, regulation proteins, and transmembrane proteins.
Roles of Tight Junction Proteins[edit]
Scaffolding Proteins — organise the transmembrane proteins, couple transmembrane proteins to other cytoplasmic proteins as well as to actin filaments.
Signaling Proteins — involved in junctions assembly, barrier regulation, and gene transcription.
Regulation Proteins — regulate membrane vesicle targeting.
Transmembrane Proteins — including junctional adhesion molecule (JAM), occludin, and claudin. It is believed that claudin is the protein molecule responsible for the selective permeability between epithelial layers.
https://en.wikipedia.org/wiki/Gastrointestinal_tract
NOTICE HOW THE THIRD LAYER IS THE MUSCULAR LAYER- THE THIRD IS ALWAYS ACTION AND MOST SOLID
The gastrointestinal tract has a form of general histology with some differences that reflect the specialization in functional anatomy.[18] The GI tract can be divided into four concentric layers in the following order:
Mucosa
Submucosa
Muscular layer
Adventitia or serosa
https://en.wikipedia.org/wiki/Large_intestine --- FOURTH IS TRANSCENDENT FIFTH ULTRA
Ascending colon[edit]
https://en.wikipedia.org/wiki/File:Dickdarm-Schema.svg
The ascending colon is the first of FOUR sections of the large intestine. It is connected to the small intestine by a section of bowel called the cecum. The ascending colon runs upwards through the abdominal cavity toward the transverse colon for approximately eight inches (20 cm).
One of the main functions of the colon is to remove the water and other key nutrients from waste material and recycle it. As the waste material exits the small intestine through the ileocecal valve, it will move into the cecum and then to the ascending colon where this process of extraction starts. The unwanted waste material is moved upwards toward the transverse colon by the action of peristalsis. The ascending colon is sometimes attached to the appendix via Gerlach's valve. The appendix, traditionally seen as a vestigial organ, has been shown to have a high concentration of lymphatic cells. In ruminants, the ascending colon is known as the spiral colon.[14][15][16]
Transverse colon[edit]
The transverse colon is the part of the colon from the hepatic flexure to the splenic flexure (the turn of the colon by the spleen). The transverse colon hangs off the stomach, attached to it by a large fold of peritoneum called the greater omentum. On the posterior side, the transverse colon is connected to the posterior abdominal wall by a mesentery known as the transverse mesocolon.
The transverse colon is encased in peritoneum, and is therefore mobile (unlike the parts of the colon immediately before and after it). Cancers form more frequently further along the large intestine as the contents become more solid (water is removed) in order to form feces.[citation needed]
The proximal two-thirds of the transverse colon is perfused by the middle colic artery, a branch of the superior mesenteric artery (SMA), while the latter third is supplied by branches of the inferior mesenteric artery (IMA). The "watershed" area between these two blood supplies, which represents the embryologic division between the midgut and hindgut, is an area sensitive to ischemia.
Descending colon[edit]
The descending colon is the part of the colon from the splenic flexure to the beginning of the sigmoid colon. One function of the descending colon in the digestive system is to store feces that will be emptied into the rectum. It is retroperitoneal in two-thirds of humans. In the other third, it has a (usually short) mesentery.[17] The arterial supply comes via the left colic artery. The descending colon is also called the distal gut, as it is further along the gastrointestinal tract than the proximal gut. Gut flora are very dense in this region.
Sigmoid colon[edit]
The sigmoid colon is the part of the large intestine after the descending colon and before the rectum. The name sigmoid means S-shaped (see sigmoid; cf. sigmoid sinus). The walls of the sigmoid colon are muscular, and contract to increase the pressure inside the colon, causing the stool to move into the rectum.
The sigmoid colon is supplied with blood from several branches (usually between 2 and 6) of the sigmoid arteries, a branch of the IMA. The IMA terminates as the superior rectal artery.
Sigmoidoscopy is a common diagnostic technique used to examine the sigmoid colon.
Rectum[edit]
The rectum is the last section of the large intestine. It holds the formed feces awaiting elimination via defecation.
FOUR SUBNUCLEI
https://en.wikipedia.org/wiki/Vestibular_nuclei
The vestibular nuclei are the cranial nuclei for the vestibular nerve.
In Terminologia Anatomica they are grouped in both the pons and the medulla in the brainstem.
There are 4 subnuclei; they are situated at the floor of the fourth ventricle.
Name Location Notes
medial vestibular nucleus (dorsal or chief vestibular nucleus) medulla (floor of fourth ventricle) corresponding to the lower part of the area acustica in the rhomboid fossa;[citation needed] the caudal end of this nucleus is sometimes termed the descending or spinal vestibular nucleus.
lateral vestibular nucleus or nucleus of Deiters medulla (upper) consisting of large cells and situated in the lateral angle of the rhomboid fossa; the dorso-lateral part of this nucleus is sometimes termed the nucleus of Bechterew.
inferior vestibular nucleus medulla (lower)
superior vestibular nucleus pons
QMR
https://en.wikipedia.org/wiki/Spermatogenesis
https://en.wikipedia.org/wiki/File:Figure_28_01_04.jpg
This is in my first book- the fourth is always different
Spermatogenesis has equivalent meiotic divisions resulting in four equivalent spermatids while oogenic meiosis is asymmetrical: only one egg is formed together with three polar bodies (four all together)
Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa.[1]
IN SPERMATOGENESIS THREE POLAR BODIES ARE LET OUT AND ONE OVUM MATURES---- THE FOURHT IS ALWAYS DIFFERENT
Some algae and the oomycetes produce eggs in oogonia. In the brown alga Fucus, all four egg cells survive oogenesis, which is an exception to the rule that generally only one product of female meiosis survives to maturity.
https://en.wikipedia.org/wiki/File:Gray5.svg
https://en.wikipedia.org/wiki/Oogenesis
QUADRANT
https://en.wikipedia.org/wiki/CHON
CHON is a mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen, oxygen, and nitrogen. They make up like 99 percent of life.
The questionable fifth is phosophorous. Nitrogen is somewhat rare, but phosphorous is extremely rare (but very important, being a part of DNA). The fourth is always different/transcendent. The fifth ultra transcendent.
I'm a paragraph. Click here to add your own text and edit me. It's easy.
I'm a paragraph. Click here to add your own text and edit me. It's easy.
I'm a paragraph. Click here to add your own text and edit me. It's easy.
FOUR ZONES OF THE LUNG
https://en.wikipedia.org/wiki/Zones_of_the_lung
This is in one of my books
The zones of the lung divide the lung into four vertical regions, based upon the relationship between the pressure in the alveoli (PA), in the arteries (Pa), in the veins (Pv) and the pulmonary interstitial pressure (Pi) :
Zone 1: PA > Pa > Pv
Zone 2: Pa > PA > Pv
Zone 3: Pa > Pv > PA
Zone 4: Pa > Pi > Pv > PA
This concept is generally attributed to an article by West et al. in 1964,[1] but was actually proposed two years earlier by Permutt et al.[2] In this article, Permutt suggests "The pressure in the pulmonary arteries and veins is less at the top than at the bottom of the lung. It is quite likely that there is a portion of the lung toward the top in an upright subject in which the pressure in the pulmonary arteries is less than alveolar pressure."
The concept is as follows: Alveolar pressure (PA) at end expiration is equal to atmospheric pressure (0 cm H20 differential pressure, at zero flow), plus or minus 2 cm H2O (1.5 mmHg) throughout the lung. On the other hand, gravity causes a gradient in blood pressure between the top and bottom of the lung of 20 mmHg in the erect position (roughly half of that in the supine position). Overall, mean pulmonary venous pressure is ~5 mmHg. Local venous pressure falls to -5 at the apexes and rises to +15 mmHg at the bases, again for the erect lung. Pulmonary blood pressure is typically in the range 25 - 10 mmHg with a mean pressure of 15 mmHg. Regional arterial blood pressure is typically in the range 5 mmHg near the apex of the lung to 25 mmHg at the base.
Zone 1 is not observed in the normal healthy human lung. In normal health pulmonary arterial (Pa) pressure exceeds alveolar pressure (PA) in all parts of the lung. It is generally only observed when a person is ventilated with positive pressure or hemorrhage. In these circumstances, blood vessels can become completely collapsed by alveolar pressure (PA) and blood does not flow through these regions. They become alveolar dead space
Zone 2 is the part of the lungs about 3 cm above the heart. In this region blood flows in pulses. At first there is no flow because of obstruction at the venous end of the capillary bed. Pressure from the arterial side builds up until it exceeds alveolar pressure and flow resumes. This dissipates the capillary pressure and returns to the start of the cycle. Flow here is sometimes compared to a starling resistor or waterfall effect.
Zone 3 comprises the majority of the lungs in health. There is no external resistance to blood flow and blood flow is continuous throughout the cardiac cycle. Flow is determined by the Ppa-Ppv difference (Ppa - Ppv), which is constant down this portion of the lung. However, transmural pressure across the wall of the blood vessels increases down this zone due to gravity. consequently the vessels wall are more stretched so the caliber of the vessels increases causing an increase in flow due to lower resistance.
Zone 4 can be seen at the lung bases at low lung volumes or in Pulmonary oedema. Pulmonary interstitial pressure (Pi) rises as lung volume decreases due to reduced radial tethering of the lung Parenchyma Pi is highest at the base of the lung due to the weight of the above lung tissue. Pi can also rise due to an increased volume of 'leaked' fluid fluid from the pulmonary vasculature aka Pulmonary oedema . An increase in Pi causes extralveolar blood vessels to reduce in caliber and so blood flow decreases. Extralveolar blood vessels are those blood vessels outside alveoli. Intralveolar Blood vessels aka Pulmonary capillaries are considered to be the thin walled vessels adjacent to alveoli which are subject to the pressure changes described by zones 1-3. Flow in zone 4 is governed by the arteriointerstitial pressure difference (Pa − Pi). This is because as Pi rises further the arterial caliber is further reduced and so resistance to flow rises, the Pa/Pv difference remains absolute since Pi is applied over both vessels.
The Ventilation/perfusion ratio is higher in zone #1 (the apex of lung) when a person is standing than it is in zone #3 (the Base of lung) because perfusion is nearly absent. However, ventilation and perfusion are highest in base of the lung, resulting in a comparatively lower V/Q ratio.
FOUR TYPES OF HUMAN TEETH
https://en.wikipedia.org/wiki/Human_tooth
The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digestion. Humans have four types of teeth: incisors, canines, premolars, and molars, each with a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.
FOUR TYPES OF TISSUE
https://en.wikipedia.org/wiki/Tissue_(biology)
Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.
https://en.wikipedia.org/wiki/Helix_bundle
A helix bundle is a small protein fold composed of several alpha helices that are usually nearly parallel or antiparallel to each other.
Contents [hide]
1 Three-helix bundles
2 Four-helix bundles
3 See also
4 References
5 External links
Three-helix bundles[edit]
An example of the three-helix bundle fold, the headpiece domain from the protein villin as expressed in chickens (PDB ID 1QQV).
Three-helix bundles are among the smallest and fastest known cooperatively folding structural domains.[1] The three-helix bundle in the villin headpiece domain is only 36 amino acids long and is a common subject of study in molecular dynamics simulations because its microsecond-scale folding time is within the timescales accessible to simulation [2][3] The 40-residue HIV accessory protein has a very similar fold and has also been the subject of extensive study.[4] There is no general sequence motif associated with three-helix bundles, so they cannot necessarily be predicted from sequence alone. Three-helix bundles often occur in actin-binding proteins and in DNA-binding proteins.
Four-helix bundles[edit]
Four-helix bundles typically consist of four helices packed in a coiled-coil arrangement with a sterically close-packed hydrophobic core in the center. Pairs of adjacent helices are often additionally stabilized by salt bridges between charged amino acids. The helix axes typically are oriented about 20 degrees from their neighboring helices, a much shallower incline than in the larger helical structure of the globin fold.[5]
The specific topology of the helices is dependent on the protein - helices that are adjacent in sequence are often antiparallel, although it is also possible to arrange antiparallel links between two pairs of parallel helices. Because dimeric coiled-coils are themselves relatively stable, four-helix bundles can be dimers of coiled-coil pairs, as in the Rop protein. Four-helix bundle can have thermal stability more than 100℃. Other examples of four-helix bundles include cytochrome, ferritin, human growth hormone, cytokine,[5] and Lac repressor C-terminal. The four-helix bundle fold has proven an attractive target for de novo protein design, with numerous de novo four-helix bundle proteins having been successfully designed by rational[6] and by combinatorial[7] methods. Although sequence is not conserved among four-helix bundles, sequence patterns tend to mirror those of coiled-coil structures in which every fourth and seventh residue is hydrophobic.
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THIS PERSON TALKS ABOUT WHAT I TALKED ABOUT I LEARNED IN MY BIOLOGY AND PSCYHOLOGY CLASSES- ANIMALS AND HUMANS GET SLOWER AT FOUR OBJECTS AND AT FIVE DECLINE COMPLETELY- 4 IS THE CUTOFF- FOR INSTANCE THERE IS AN ANIMAL THAT GIVES THREE WARNING CALLS IF IT IS FAKING AT THE FOURTH THE ANIMALS SORT OF STOP LISTENING AT FIVE THEY DO NOT LISTEN AT ALL
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291302/
The magical number four: A biological, historical and mythological enigma
Hans J. Grosscorresponding author
Author information ► Copyright and License information ►
This article has been cited by other articles in PMC.
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Abstract
Precise recognition of small object numbers without counting is a widespread phenomenon. It is well documented for humans and for a series of non-human vertebrates. Recently this has been confirmed for an invertebrate, the honeybee.1 This type of inborn numerical competence has been named “subitizing”, from the Latin subito = suddenly, immediately. It differs from the classical, sequential counting which has to be trained, starting with the help of our fingers. For humans it had been established since 1871 by Jevons2 that only up to four objects are precisely recognized and memorized. Under conditions which do not allow sequential counting, mistakes start to occur in case of more than four objects. This result has been confirmed whenever the range of visual attention has been carefully tested under a variety of rigorous conditions. It provides the basis for a novel hypothesis about the evolution of counting and numbering systems in ancient civilizations.3
Keywords: honeybee, magical number four, numerical competence, subitizing
Using a “delayed match-to-sample” setup in a Y-maze we determined the numerical capacity of honeybees. Even under variable and complex conditions, the insects were able to choose the correct object numbers in more than 80% of the decisions after only 4 rounds of training. Thus, up to 3 objects were memorized for about 5 sec during the flight from the entrance to the decision chamber of our setup, but 4 objects were recognized with less precision and with some difficulties,1 indicating that the borderline of numerical capacity in this species is between 3 and 4 objects. We were especially careful to avoid any possibility of pattern recognition which would render our results meaningless. Similar numerical capacities have previously been observed for a number of vertebrates.1 Partly those results were obtained under less stringent conditions because the very rigorous “delayed match-to-sample” setup had not been used or could not be used for all species. Moreover, many such studies, especially with “counting” animals, do not differentiate strictly enough between genuine counting, “subitizing” and pattern recognition. However, under rigorous testing conditions animals “subitize,” i.e., recognize and memorize object numbers without the ability of real counting.4
In summary, object numbers of more than three or four consequently have the meaning of “many” for honeybees and for other, rigorously examined animals. This seemingly innate ability of humans, of non-human vertebrates and of an insect, the honeybee, to recognize and memorize up to four objects correctly without sequential counting raises the following questions:
(a) What is the benefit for humans and animals to be able to “subitize” object numbers up to four precisely?
We can only speculate about the benefits of this ability. For early hominids, who certainly were not able to count as we do, the ability to estimate within the fraction of a second whether two, four or “many” lions are watching them, the decision to attack and fight, to defend or to try to escape might have been a matter of life and death. For animals the ability to estimate whether two, four or “many” hungry carnivores are approaching may also have been crucial for survival. In case of the honeybee we have speculated that the memorization of object numbers (trees, houses or other landmarks) may be useful for their orientation and help them to find back home. In addition it may help the foraging bee to recognize branches with less than three to four or with “many” blossoms, or to estimate the number of foraging bees on a blossom, allowing the decision to join or to quit.1
(b) Why is there a limit of up to 4 objects in case of humans and animals, even in case of honeybees?
We obviously are dealing with an inborn ability of many species but we do not know the answer – maybe we ask the wrong question.
(c) What is the underlying neurobiological process?
The underlying neurobiological process is still unknown, although neuroimaging techniques like functional magnetic resonance imaging have revealed that defined regions of the brain are activated during calculations.
(d) What is the driving force or evolutionary pressure which sustains this numerical competence from bees to humans?
The driving force for having the inborn numerical competence to differentiate between 2, 3, 4 or “many” objects in a fraction of a second without counting may be or may have been an advantage in the struggle for survival for humans and non-human vertebrates. For honeybees, such a selective advantage appears less essential. Although the ability to “subitize” is a primitive, archaic ability, it appears justified to rule out the possibility of divergent evolution because the enormous evolutionary distances between humans and honeybees. If we consider the possibility of convergent evolution, we end up again with the question of selective advantage for the survival of a species involving exactly the same magical number four in humans and honeybees. What is the benefit for a pigeon mother to know whether she has four or “many” eggs in her nest? Pigeons have been shown to have numerical competence – but does this have any meaning for the survival and for the evolutionary success of the species? We have to admit that we do not know the answer. Does a look at the role of the magical number four in history and mythology help us to understand its biological significance?
(e) The role of the “magical” number 4 in history.
The earliest use of number 4 is the puzzling presentation of honeybees and honeybee hieroglyphs with 4 legs as early as 4.600 y ago throughout the history of ancient Egypt. There is no explanation why the correct number of 6 legs was not implemented by the Egyptian artists although an efficient numbering and counting system had been available.3
Another puzzling episode goes back to Aristotle (384–322 B.C.) who knew that animals with 4 legs never have wings. He wondered that the dayfly, whose short life-cycle he precisely described (4) is an exception in that this insect has wings despite of having 4 legs. Other examples for the importance of number four are the 4 seasons, the 4 sides and the 4 corners of a square, the rare four-leafed clover, a symbol of good luck in some cultures, in Hinduism the 4 faces of Brahma the creator, the 4 directions, the 4 elements water, fire earth and air and, finally, the 4 human temperaments: sanguine, choleric, melancholic and phlegmatic.
The 4 Cardinal Virtues sapientia (wisdom), iustitia (justice), fortitudo (courage) and temperantia (moderation) are frequently associated with Christian religion. Historically, however, these virtues go back to Plato (428/427–348/347 B.C.).
In a religious context the following examples for the importance of the “magical” number 4 come to mind:
(i) The possibility for a Muslim to have up to 4 legal wives if he can support them. This rule has often been misinterpreted and misunderstood, but it had the function to support widows, with and without children, whose husbands had lost their lives on the battlefields. But why precisely 4?
(ii) The 4 gospels and their corresponding evangelists. It was the Roman emperor Konstantin I. who decided that an obligatory, state-controlled religion with a single god – instead of the vast variety of gods, goddesses, half-gods, god-like previous emperors and cryptic oriental rites - would be an enormous advantage for ruling his huge but heterogeneous empire. He assembled more than 300 bishops at the Council of Nicaea in the year 325, and under his guidance – the religious delegates held different opinions about the existence of one single God or of a Trinity – only 4 out of more than hundred gospels existing at that time were selected as authentic. But why 4 and not 3 or 5 gospels? Could this be a reference to the 4 corners of the quadratic celestial Jerusalem5 or because 4 is the first non-prime in the endless sequence of numbers?
(f) The occurrence of the “magical” number 4 in mythology.
Among the oldest cases presented here are the 4 celestial emblems of the Chinese emperor: The Black Tortoise ( = North), the White Tiger ( = West), the Red Bird (Phoenix = South) and the Blue Dragon ( = East), ancient symbols which are several thousand years old.
In summary, questions about the evolution and the putative evolutionary advantage to “subitize” up to 4 objects without counting for the survival of a species remain without answer. We do not know why is this “magical number four” is common among humans, non-human vertebrates and honeybees. Moreover, a synopsis of the occurrence of this magical number in culture, religion and mythology highlights its universal significance but does not enlighten our understanding of the widespread, archaic, inborn ability for “subitinization.” The “magical number four” remains a biological, historical and mythological enigma.
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Acknowledgments
I thank my colleagues Profs. H. Beier, H. Hoehn and J. Tautz for critical reading of this manuscript and Dr. Mario Pahl for helpful suggestions.
https://en.wikipedia.org/wiki/Bison
The extinction of four species of bison (B. antiquus, B. latifrons, B. occidentalis, and B. priscus) was due to natural selection (see section Evolution and genetic history).
Of the four extinct species, three were North American endemics: Bison antiquus, B. latifrons, and B. (antiquus) occidentalis. The fourth, B. priscus, ranged across steppe environments from Western Europe, through Central Asia, East Asia including Japan,[1][2] and onto North America.
FOUR SPECIES
https://en.wikipedia.org/wiki/Ariopsis_(fish)
Ariopsis is a genus of sea catfishes found along the Pacific and Atlantic coasts of the Americas.
Species[edit]
There are currently four described species in this genus:[1]
Ariopsis assimilis (Günther, 1864) (Mayan sea catfish)
Ariopsis felis (Linnaeus, 1766) (Hardhead sea catfish)
Ariopsis guatemalensis (Günther, 1864) (Blue sea catfish)
Ariopsis seemanni (Günther, 1864) (Tete sea catfish)
http://www.outdoorhub.com/stories/2014/10/16/4-largest-bears-ever-taken-hunters/
There are four species of bears in North America, and all of them have killed people; some more than others. That’s just one of the reasons why people get an adrenaline surge when they encounter one.
THERE ARE FOUR GROUPS OF SEEDBEARING PLANTS
https://en.wikipedia.org/wiki/Plant
Early seed plants are gymnosperms, as the ovules and subsequent seeds are not enclosed in a protective structure (carpels or fruit), but are found naked, typically on cone scales. Pollen typically lands directly on the ovule. Four surviving groups remain widespread now, particularly the conifers, which are dominant trees in several biomes.
FOUR GENERA
https://en.wikipedia.org/wiki/Glaucophyte
Classification[edit]
Only 13 species of glaucophytes are known, none of which is particularly common in nature.[1] The four included genera are:
Glaucocystis is immotile, though it retains very short vestigial flagella, and has a cellulose wall.
Cyanophora is motile and lacks a cell wall.
Gloeochaete has both motile and immotile stages, and its cell wall does not appear to be composed of cellulose.
Cyanoptyche is the least studied of the four genera
http://itech.fgcu.edu/faculty/sstans/colohuff.html
The black and white colobus are made up of four species: colobus abyssinicus, colobus polykomos (Colobus 263), colobus satanas, and colobus guereza
The Archaeidae are a spider family with about 70 described species in four genera, as of October 2016
https://en.wikipedia.org/wiki/Archaeidae
Extant genera[edit]
As of October 2016, four extant genera are accepted by the World Spider Catalog:[1]
Afrarchaea Forster & Platnick, 1984 – South Africa, Madagascar
Austrarchaea Forster & Platnick, 1984 – Australia
Eriauchenius O. Pickard-Cambridge, 1881 – Madagascar, South Africa
Zephyrarchaea Rix & Harvey, 2012 – Australia
FOUR COLORS DOBERMAN
https://en.wikipedia.org/wiki/Doberman_Pinscher
TWO different color genes exist in the Doberman, one for black (B) and one for color dilution (D). There are nine possible combinations of these alleles (BBDD, BBDd, BbDD, BbDd, BBdd, Bbdd, bbDD, bbDd, bbdd), which result in four different color phenotypes: black, red, blue, and fawn (Isabella).
FOUR COAT PATTERNS
https://en.wikipedia.org/wiki/American_Paint_Horse
Each Paint Horse has a particular combination of white and another color of the equine spectrum. Most common are horses with white spots combined with black, bay, brown, and chestnut or sorrel. Less common are horses with spot colors influenced by dilution genes such as palomino, buckskin, cremello, perlino, pearl or "Barlink factor", and champagne,[4] various shades of roan, or various shades of dun, including grullo.[5] Paints may also carry the gray gene and have spots that eventually fade to white hair, though retaining pigmented skin underneath the areas that were once dark.
Spots can be any shape or size, except leopard complex patterning, which is characteristic of the Appaloosa, and located virtually anywhere on the Paint's body. Although Paints come in a variety of colors with different markings and different underlying genetics, these are grouped into only four defined coat patterns: overo (includes frame, splash and sabino), tobiano and tovero and solid.[6]
https://en.wikipedia.org/wiki/Rhesus_macaque
32 is two sixteens
The rhesus macaque has 32 teeth with a dental formula of 2.1.2.3/2.1.2.3 and bilophodont molars. The upper molars have four cusps: paracone, metacone, protocone, and hypocone. The lower molars also have four cusps: metaconid, protoconid, hypoconid, and entoconid.
FOUR TYPES OF SHARK TEETH
https://en.wikipedia.org/wiki/Shark_tooth
A shark tooth is one of the numerous teeth of a shark. A shark tooth contains resistant calcium phosphate materials.[1] Sharks continually shed their teeth; some Carcharhiniformes shed approximately 35,000 teeth in a lifetime, replacing those that fall out.[2] There are four basic types of shark teeth: dense flattened, needle-like, pointed lower with triangular upper, and non-functional. The type of tooth that a shark has depends on its diet and feeding habits.
FOUR CHAIN TETRAMER
https://en.wikipedia.org/wiki/HBB
HBB interacts with Hemoglobin, alpha 1 (HBA1) to form haemoglobin A, the major haemoglobin in adult humans.[7][8] The interaction is two-fold. First, one HBB and one HBA1 combine, non-covalently, to form a dimer. Secondly, two dimers combine to form the four-chain tetramer, and this becomes the functional haemolglobin.[9]
https://en.wikipedia.org/wiki/Horse
Before the availability of DNA techniques to resolve the questions related to the domestication of the horse, various hypotheses were proposed. One classification was based on body types and conformation, suggesting the presence of four basic prototypes that had adapted to their environment prior to domestication.[105] Another hypothesis held that the four prototypes originated from a single wild species and that all different body types were entirely a result of selective breeding after domestication.[156] However, the lack of a detectable substructure in the horse has resulted in a rejection of both hypotheses.
FOUR SPECIES BANDED PENGUINS
There are four living species of penguins known as banded penguins, and all have similar coloration
https://en.wikipedia.org/wiki/Banded_penguin
The four extant species of banded penguins (Spheniscus) are:
Image Common name Binomial name
Megallanic penguin Magellanic penguin Spheniscus magellanicus
Humboldt penguin Humboldt penguin Spheniscus humboldti
Galápagos penguin Galapagos penguin Spheniscus mendiculus
African penguin African penguin, black-footed or jackass penguin Spheniscus demersus
FOUR HUMAN GLYCOPROTEIN HORMONES
https://en.wikipedia.org/wiki/Glycoprotein_hormones,_alpha_polypeptide
Glycoprotein hormones, alpha polypeptide is a protein that in humans is encoded by the CGA gene.[3]
The gonadotropin hormones, human chorionic gonadotropin (hCG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH) are heterodimers consisting of alpha and beta subunits (also called chains) that are associated non-covalently. The alpha subunits of these four human glycoprotein hormones are identical; however, their beta chains are unique and confer biological specificity. The protein encoded by this gene is the alpha subunit and belongs to the glycoprotein hormones alpha chain family.[4]
https://en.wikipedia.org/wiki/Canidae
By 0.3 Mya, a number of subspecies of the gray wolf (Canis lupus) had developed and had spread throughout Europe and northern Asia.[21] The gray wolf colonized North America during the late Rancholabrean era across the Bering land bridge, there being at least three separate invasions, with each one consisting of one or more different Eurasian gray wolf clades.[22] MtDNA studies have shown that there are at least four extant C. lupus lineages
FOUR CHLOROPLAST LINEAGES- CHLOROPLASTS CONDUCT PHOTOSYNTHESIS
https://en.wikipedia.org/wiki/Chloroplast
All primary chloroplasts belong to one of four chloroplast lineages—the glaucophyte chloroplast lineage, the amoeboid Paulinella chromatophora lineage, the rhodophyte (red algal) chloroplast lineage, or the chloroplastidan (green) chloroplast lineage.[27] The rhodophyte and chloroplastidan lineages are the largest,[16] with chloroplastidan (green) being the one that contains the land plants
Chloroplast lineages
A primary endosymbiosis
event gave rise to four main
lineages of chloroplasts in
the glaucophytes, Paulinella, chlorophyta,
and rhodophyta.[27]
Some of these algae were
subsequently engulfed by
other algae, becoming
secondary (or tertiary)
endosymbionts.[14][16
FOUR MAJOR GROUPS OF ARTHROPOODS- FOURTH DIFFERENT
https://en.wikipedia.org/wiki/Arthropod
The most conspicuous specialization of segments is in the head. The four major groups of arthropods – Chelicerata (includes spiders and scorpions), Crustacea (shrimps, lobsters, crabs, etc.), Tracheata (arthropods that breathe via channels into their bodies; includes insects and myriapods), and the extinct trilobites – have heads formed of various combinations of segments, with appendages that are missing or specialized in different ways
https://en.wikipedia.org/wiki/Tetragonula_iridipennis
Tetragonula iridipennis belongs to the smaller Iridipennis species group which includes four primary species: Tetragonula iridipennis, Tetragonula praeterita, Tetragonula ruficornis, and Tetragonula bengalensis. These four species were proposed in the 19th century and were poorly characterized. They have since not been directly compared via molecular studies; therefore there is uncertainty about whether they are in fact separate species.[
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STEROIDS HAVE FOUR RINGS THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Steroid
A steroid is an organic compound with four rings arranged in a specific molecular configuration. Examples include the dietary lipid cholesterol, the sex hormones estradiol and testosterone[2]:10–19 and the anti-inflammatory drug dexamethasone.[3] Steroids have two principal biological functions: certain steroids (such as cholesterol) are important components of cell membranes which alter membrane fluidity, and many steroids are signaling molecules which activate steroid hormone receptors.
The steroid core structure is composed of seventeen carbon atoms, bonded in four "fused" rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Steroids vary by the functional groups attached to this four-ring core and by the oxidation state of the rings. Sterols are forms of steroids with a hydroxyl group at position three and a skeleton derived from cholestane.[1]:1785f [4] They can also vary more markedly by changes to the ring structure (for example, ring scissions which produce secosteroids such as vitamin D3).
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https://en.wikipedia.org/wiki/Vogt–Koyanagi–Harada_disease
The sequence of clinical events in VKH is divided into four phases: prodromal, acute uveitic, convalescent, and chronic recurrent.[2][5][6]
FOUR PHASES COURTSHIP
https://en.wikipedia.org/wiki/Courtship_disorder
Courtship disorder is a theoretical construct in sexology in which a certain set of paraphilias are seen as specific instances of anomalous courtship instincts in men.[1] The specific paraphilias are biastophilia (paraphilic rape), exhibitionism, frotteurism, telephone scatologia, and voyeurism. According to the courtship disorder hypothesis, there is a species-typical courtship process in human males consisting of four phases, and anomalies in different phases result in one of these paraphilic sexual interests. That is, instead of being independent paraphilias, this theory sees these sexual interests as individual symptoms of a single underlying disorder.[2]
Contents [hide]
1 Courtship disorder hypothesis
2 Evidence and acceptance of the theory
3 See also
4 References
Courtship disorder hypothesis[edit]
According to the courtship disorder hypothesis, there is a species-typical courtship process in humans consisting of four phases.[3][4] These phases are: "(1) looking for and appraising potential sexual partners; (2) pretactile interaction with those partners, such as by smiling at and talking to them; (3) tactile interaction with them, such as by embracing or petting; (4) and then sexual intercourse."[5]
The associations between these phases and these paraphilias were first outlined by Kurt Freund,[6][7] the originator of the theory: A disturbance of the search phase of courtship manifests as voyeurism, a disturbance of the pretactile interaction phase manifests as exhibitionism or telephone scatologia, a disturbance of the tactile interaction phase manifests as toucheurism or frotteurism, and the absence of the courtship behavior phases manifests as paraphilic rape (i.e., biastophilia). According to Freund, these paraphilias "can be conceptualized as a preference for a pattern of behavior or erotic fantasy in which one of these four phases of sexual interaction is intensified and distorted to such an extent that it appears to be a caricature of the normal, while the remaining phases are either omitted entirely or are retained only in a vestigial way."[8]
https://en.wikipedia.org/wiki/Shoulder_problem
Four filmy sac-like structures called bursa permit smooth gliding between bone, muscle, and tendon. They cushion and protect the rotator cuff from the bony arch of the acromion.
THERE ARE FOUR TYPES OF BURSA
https://en.wikipedia.org/wiki/Synovial_bursa
There are four types of bursa: adventitious, subcutaneous, synovial, and sub-muscular. Among these, only adventitious is non-native. When any surface of the body is subjected to repeated stress, an adventitious bursa develops under it. Examples are Students' elbow and bunion.
https://en.wikipedia.org/wiki/File:Levels_of_structural_organization_of_a_protein.svg
https://en.wikipedia.org/wiki/Denaturation_(biochemistry)
Functional proteins have four levels of structural organization:
1) Primary Structure : the linear structure of amino acids in the polypeptide chain
2) Secondary Structure : hydrogen bonds between peptide group chains in an alpha helix or beta sheet
3) Tertiary Structure : three-dimensional structure of alpha helixes and beta helixes folded
4) Quaternary Structure : three-dimensional structure of multiple polypeptides and how they fit together
The four valves of the heart are:
https://simple.wikipedia.org/wiki/Heart
Atria to ventricle valves
Tricuspid valve – blood goes from right atrium to right ventricle
Mitral valve – blood goes from left atrium to left ventricle
Ventricles to arteries
Pulmonic valve – blood goes out of the right ventricle to the lungs (through the pulmonic artery)
IT HAS FOUR CHAINS AND FOUR IG LIKE DOMAINS
https://en.wikipedia.org/wiki/Immunoglobulin_E
Immunoglobulin E (IgE) is a type of antibody (or immunoglobulin (Ig) "isotype") that has only been found in mammals. IgE is synthesised by plasma cells. Monomers of IgE consist of two heavy chains (ε chain) and two light chains, with the ε chain containing 4 Ig-like constant domains (Cε1-Cε4).[1
IT HAS FOUR CHAINS TWO HEAVY AND TWO LIGHT- I LEARNED ABOUT THIS IN BIOCHEMISTRY CLASS I SAT IN
https://en.wikipedia.org/wiki/Immunoglobulin_D
Secreted IgD is produced as a monomeric antibody with two heavy chains of the delta (δ) class, and two Ig light chains.
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FOUR ISOLATED POPULATIONS
https://en.wikipedia.org/wiki/Bongo_(antelope)
The Bongo Surveillance Programme, working alongside the Kenya Wildlife Service, have recorded photos of bongos at remote salt licks in the Aberdare Forests using camera traps, and, by analyzing DNA extracted from dung, have confirmed the presence of bongo in Mount Kenya, Eburru and Mau forests. The programme estimate as few as 140 animals left in the wild – spread across four isolated populations. Whilst captive breeding programmes can be viewed as having been successful in ensuring survival of this species in Europe and North America, the situation in the wild has been less promising. Evidence exists of bongo surviving in Kenya. However, these populations are believed to be small, fragmented, and vulnerable to extinction.
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https://en.wikipedia.org/wiki/Primate
The vervet monkey gives a distinct alarm call for each of at least four different predators, and the reactions of other monkeys vary according to the call.
ALSO I LEARNED IT IN MY ANIMAL BEHAVIOR CLASS AT UCSD AT THREE FALSE CALLS MONKEYS STILL RESPOND EQUALLY AT FOUR SOME STOP RESPONDING AT FIVE FALSE CALLS NONE RESPOND- FOURTH ALWAYS DIFFERENT FIFTH ALWAYS QUESTIONABLE
FOUR OF THEM
https://en.wikipedia.org/wiki/Boeing_E-4
The Boeing E-4 Advanced Airborne Command Post, with the project name "Nightwatch",[2] is a strategic command and control military aircraft operated by the United States Air Force (USAF). The E-4 series was specially modified from the Boeing 747-200B. The E-4 serves as a survivable mobile command post for the National Command Authority, namely the President of the United States, the Secretary of Defense, and successors. The four E-4Bs are operated by the 1st Airborne Command and Control Squadron of the 595th Command and Control Group located at Offutt Air Force Base, near Omaha, Nebraska. An E-4B is denoted a "National Airborne Operations Center" when in action.[3]
In November 1973 it was reported that the program cost was estimated to total $548 million for seven 747s, six as operational command posts and one for research and development.[5] In December 1973 a fourth aircraft was ordered; it was fitted with more advanced equipment, resulting in the designation E-4B. On 21 December 1979 Boeing delivered the first E-4B (AF Serial Number 75-0125),[4] which was distinguished from the earlier version by the presence of a large streamlined radome on the dorsal surface directly behind the upper deck. This contains the aircraft's SHF satellite antenna.[6]
FOUR PARASYMPATHETIC GANGLIA
https://en.wikipedia.org/wiki/Ciliary_ganglion
It is one of four parasympathetic ganglia of the head and neck. (The others are the submandibular ganglion, pterygopalatine ganglion, and otic ganglion).
EIGHT PAIRS OF LEGS-- 16 LEGS
https://en.wikipedia.org/wiki/Phrynus_longipes
The body of P. longipes can measure up to 19 millimetres (0.75 in) long, but its front legs can reach 250 millimetres (9.8 in) long.[2] Like other Amblypygi, Phrynus longipes has eight pairs of legs with six used for walking and the first employed as sensory organs for detecting prey and navigating their environment. Its cephalothorax is wider than it is long and is outfitted with eight eyes. One pair of eyes is located in front and 3 more pairs on the sides. They produce no venom, but instead have arm-like pedipalps and a pair of smaller chelicerae.
QUATERNION EAGLE
https://en.wikipedia.org/…/Coats_of_arms_of_the_Holy_Roman_…
Quaternion Eagle[edit]
The Quarter Eagle, hand-coloured woodcut (c. 1510) by Hans Burgkmair.
One rendition of the coat of the empire was the "Quaternion Eagle" (so named after the imperial quaternions) printed by David de Negker of Augsburg, after a 1510 woodcut by Hans Burgkmair. It showed a selection of 56 shields of various Imperial States in groups of four on the feathers of a double-headed eagle supporting, in place of a shield, Christ on the Cross. The top, larger shields, are those of the seven Prince Electors, the ecclesiastical: Trier, Cologne and Mainz as well as of the titular "Prefect of Rome" on the right wing; the secular: Bohemia, Electorate of the Palatinate, Saxony and Brandenburg on the left. The depiction also appeared on the Imperial Eagle beaker
https://en.wikipedia.org/wiki/Haploblepharus
Haploblepharus is a genus of catshark, and part of the family Scyliorhinidae, containing four species of shysharks. Their common name comes from a distinctive defensive behavior in which the shark curls into a circle and covers its eyes with its tail. The genus is endemic to southern Africa, inhabiting shallow coastal waters. All four species are small, stout-bodied sharks with broad, flattened heads and rounded snouts. They are characterized by very large nostrils with enlarged, triangular flaps of skin that reach the mouth, and deep grooves between the nostrils and the mouth. Shysharks are bottom-dwelling predators of bony fishes and invertebrates. They are oviparous, with the females laying egg capsules. These harmless sharks are of no commercial or recreational interest, though their highly limited distributions in heavily fished South African waters are of potential conservation concern.
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FOUR STAGES DISEASE CHINESE MEDICINE
https://en.wikipedia.org/wiki/Ye_Tianshi
Ye Tianshi
From Wikipedia, the free encyclopedia
(Redirected from Four stages)
Ye Tianshi
Native name 葉天士
Born 1667
Died 1747
Occupation Physician
Era Qing dynasty
Ye Tianshi (1667-1747) was a Chinese medical scholar who was the major proponent of the "school of warm diseases".[1] His major work, Wen-re Lun (Discussion of Warm Diseases) published in 1746,[2] divided the manifestations of diseases into four stages: wei (defensive phase), qi (qi-phase), ying (nutrient-phase), and xue (blood-phase).[1]
Life[edit]
Ye Tianqi was born in 1666. His father as well as his grandfather, Ye Shi, were also physicians.[3] He learned medicine from his father and, following his father's death, from his father's pupil of the surname Zhu.[3]
Work[edit]
Ye Tianshi wrote little and most works attributed to him were compiled by his followers after his death.[3] He is best known for proposing that feverish diseases progressed along four stages, a theory he laid out in his book Discussion of Warm Diseases.[1] Those stages are wei (defensive phase), qi (qi-phase or active qian phase), ying (nutrient-phase), and xue (blood-phase).[1] The characteristics of wei are fever, sensitivity to cold, headache, and rapid pulse. Next qi is the phase of most active disease, characterized by high fever, sweating, dry mouth, and rapid pulse. Ying is characterized by rising fever at night, agitation, confusion, and weak pulse. Finally, xue consists of agitation, rash, and in some cases vomiting of blood or blood in the stool or urine.[3] In his treatments for feverish diseases, Ye recommended cooling substances.[1]
https://en.wikipedia.org/wiki/Fourth_ventricle
The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ventricle. The fourth ventricle extends from the cerebral aqueduct (aqueduct of Sylvius) to the obex, and is filled with cerebrospinal fluid (CSF).
https://en.wikipedia.org/wiki/Ventricular_system
The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. The ventricular system is continuous with the central canal of the spinal cord (from the fourth ventricle) allowing for the flow of CSF to circulate. All of the ventricular system and the central canal of the spinal cord is lined with ependyma, a specialised form of epithelium.
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NORMALLY IT IS SAID THAT THERE IS THREE LAYER OF THE CRANIAL MENINGES- BUT THE FOURTH CSF IS DIFFERNT
http://www.interactive-biology.com/6715/structure-and-function-of-the-cranial-meninges/
This layer of protective tissues is collectively named the “meninges” but is actually composed of 3 main layers: The Dura mater, the Arachnoid layer, and the Pia mater.
https://en.wikipedia.org/wiki/Pia_mater
The CSF, pia mater, and other layers of the meninges work together as a protection device for the brain, with the CSF often referred to as the FOURTH layer of the meninges.
FOUR AREAS OF INFOLDING
https://en.wikipedia.org/wiki/Meninges
The dura mater (Latin: tough mother) (also rarely called meninx fibrosa or pachymeninx) is a thick, durable membrane, closest to the skull and vertebrae. The dura mater, the outermost part, is a loosely arranged, fibroelastic layer of cells, characterized by multiple interdigitating cell processes, no extracellular collagen, and significant extracellular spaces. The middle region is a mostly fibrous portion. It consists of two layers: the endosteal layer, which lies closest to the calvaria (skullcap), and the inner meningeal layer, which lies closer to the brain. It contains larger blood vessels that split into the capillaries in the pia mater. It is composed of dense fibrous tissue, and its inner surface is covered by flattened cells like those present on the surfaces of the pia mater and arachnoid mater. The dura mater is a sac that envelops the arachnoid mater and surrounds and supports the large dural sinuses carrying blood from the brain toward the heart.
The dura has four areas of infolding:
Falx cerebri, the largest, sickle-shaped; separates the cerebral hemispheres. Starts from the frontal crest of frontal bone and the crista galli running to the internal occipital protuberance.
Tentorium cerebelli, the second largest, crescent-shaped; separates the occipital lobes from cerebellum. The falx cerebri attaches to it giving a tentlike appearance.
Falx cerebelli, vertical infolding; lies inferior to the tentorium cerebelli, separating the cerebellar hemispheres.
Diaphragma sellae, smallest infolding; covers the pituitary gland and sella turcica.
FOUR SUBSPECIES OF CHIMPANZEE
https://en.wikipedia.org/wiki/Common_chimpanzee
Four subspecies of the common chimpanzee have been recognised,[11][12] with the possibility of a fifth:[13]
Central chimpanzee or tschego, P. t. troglodytes, in Cameroon, the Central African Republic, Equatorial Guinea, Gabon, the Republic of the Congo, and the Democratic Republic of the Congo
Western chimpanzee, P. t. verus, in Guinea, Guinea Bissau, Mali, Senegal, Sierra Leone, Liberia, Ivory Coast, and Ghana
Nigeria-Cameroon chimpanzee, P. t. ellioti (also known as P. t. vellerosus),[11] in Nigeria and Cameroon
Eastern chimpanzee, P. t. schweinfurthii, in the Central African Republic, South Sudan, the Democratic Republic of the Congo, Uganda, Rwanda, Burundi, Tanzania, and Zambia
FOUR PARTS CHIMPANZEE VOCALIZATION
Vocalizations are also important in chimp communication. The most common and important call in adults is the "pant-hoot". These calls are made when individuals are excited.[21] Pant-hoots are made of four parts, starting with soft "hoos" that get louder and louder and climax into screams and sometimes barks; the former die down to soft "hoos" again as the call ends.[53] Submissive individuals will make "pant-grunts" towards their superiors.[21][44] Chimps use distance calls to draw attention to danger, food sources, or other community members.[21] "Barks" may be made as "short barks" when hunting and "tonal barks" when sighting large snakes.[53]
FOUR GENERA OF HOMINIDS
https://en.wikipedia.org/wiki/Hominidae
The Hominidae (/hɒˈmɪnᵻdiː/), whose members are known as great apes[note 1] or hominids, are a taxonomic family of primates that includes seven extant species in four genera: Pongo, the Bornean and Sumatran orangutan; Gorilla, the eastern and western gorilla; Pan, the common chimpanzee and the bonobo; and Homo, the human (and though not extant, the near-human ancestors and relatives (e.g., the Neanderthal)).[1]
FOUR GENERA OF GIBBONS
Gibbons are apes in the family Hylobatidae. The family historically contained one genus, but now is split into four genera.
https://en.wikipedia.org/wiki/File:Distribución_hylobatidae.png
https://en.wikipedia.org/wiki/Gibbons
The family is divided into four genera based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50).[2][9]
Family Hylobatidae: gibbons[1][9][10]
Genus Hoolock
Western hoolock gibbon, H. hoolock
Eastern hoolock gibbon, H. leuconedys
Skywalker hoolock gibbon, H. tianxing[11]
Genus Hylobates: dwarf gibbons
Lar gibbon or white-handed gibbon, H. lar
Malaysian lar gibbon, H. l. lar
Carpenter's lar gibbon, H. l. carpenteri
Central lar gibbon, H. l. entelloides
Sumatran lar gibbon, H. l. vestitus
Yunnan lar gibbon, H. l. yunnanensis
Bornean white-bearded gibbon, H. albibarbis
Agile gibbon or black-handed gibbon, H. agilis
Müller's Bornean gibbon, H. muelleri
Müller's grey gibbon, H. m. muelleri
Abbott's grey gibbon, H. m. abbotti
Northern grey gibbon, H. m. funereus
Silvery gibbon, H. moloch
Western silvery gibbon or western Javan gibbon, H. m. moloch
Eastern silvery gibbon or central Javan gibbon, H. m. pongoalsoni
Pileated gibbon or capped gibbon, H. pileatus
Kloss's gibbon, Mentawai gibbon or bilou, H. klossii
Genus Symphalangus
Siamang, S. syndactylus
Genus Nomascus: crested gibbons
Northern buffed-cheeked gibbon, N. annamensis
Concolor or black crested gibbon, N. concolor
N. c. concolor
N. c. lu
N. c. jingdongensis
N. c. furvogaster
Eastern black crested gibbon or Cao Vit black crested gibbon, N. nasutus
Hainan black crested gibbon, N. hainanus
Northern white-cheeked gibbon, N. leucogenys
Southern white-cheeked gibbon, N. siki
Yellow-cheeked gibbon, N. gabriellae
FOURTH IS ALWAYS DIFFERENT GIBBONS FOUR GENERA
https://en.wikipedia.org/wiki/Hoolock_gibbon
The classification of this gibbon has changed several times in the past few years. Classically, all gibbons were classified in the genus Hylobates, with the exception of the siamang. After some studies, the genus was divided into three subgenera (including the siamang's Symphalangus), and then into four (recognizing Bunopithecus as the hoolock subgenus distinct from other gibbon subgenera). These four subgenera were elevated to full genus status
https://en.wikipedia.org/wiki/Hylobates
The genus Hylobates /ˌhaɪloʊˈbeɪtiːz/ is one of the four genera of gibbons. Its name means ‘forest walker’, from the Greek hūlē (ὕλη, ‘forest’) and bates (βάτης, ‘one who treads’).[3][4]
It was once considered the only genus, but recently its subgenera (Hoolock [formerly Bunopithecus], Nomascus, and Symphalangus) have been elevated to the genus level.[1][5] Hylobates remains the most speciose and widespread of gibbon genera, ranging from southern China (Yunnan) to western and central Java.
SIAMANG ARE KNOWN FOR THEIR COMPLEX VOCAL STRUCTURE AMONG APES- THEY HAVE FOUR DISTINCT CLASSES OF VOCALIZATIONS
https://en.wikipedia.org/wiki/Siamang
Siamang duetting differs from other species because it has a particularly complex vocal structure. Four distinct classes of vocalizations have been documented: booms, barks, ululating screams, and bitonal screams. Females typically produce long barks and males generally produce bitonal screams, but both sexes have been known to produce all four classes of vocalizations.[17]
New Research Says There Are Only Four Emotions
The thing was, as time went on, the face showed the distinction between the two, but when the emotion first hit, the face signals are very similar, suggesting, the researchers say, that the distinction between anger and disgust and between surprise and fear, is socially, not biologically based.
This leaves us with four "basic" emotions, according to this study: happy, sad, afraid/surprised, and angry/disgusted. These, the researchers say, are our biologically based facial signals—though distinctions exist between surprise and fear and between anger and disgust, the experiment suggests that these differences developed later, more for social reasons than survival ones.
"Our data reflect that the six basic facial expressions of emotion, like languages, are likely to represent a more complex set of modern signals and categories evolved from a simpler system of communication in early man developed to subserve developing social interaction needs," the authors wrote. By that they mean these four emotions are the basic building blocks from which we develop our modern, complex, emotional stews.
http://www.reverie.com/wp/the-four-stages-of-sleep-how-they-impact-you-as-an-athletic
Four Stages of Sleep – How They Impact You as an Athlete
Sleep occurs in cycles throughout the night, with each sleep cycle taking approximately 90 minutes. Our body’s biological clock controls all of this, and technically the sleep cycle is one of our many “circadian rhythms”. There are 4 identifiable stages in each sleep cycle, and each of them has a significant impact on athletic performance and improvement.
Stage 1 – Lasts for approximately 20 minutes and is the stage where the heart rate slows and the body temperature begins to cool down. The brain activity during this time shows up in “spindles”, which are essentially tightly packed brain wave patterns. These spindles have been linked to muscle memory and internalizing movements learned during the day.
Stages 2 and 3 – Stage 2 is the transition from light to deep sleep, and Stage 3 is complete deep sleep where the body produces very slow waves called Delta Waves. This stage of sleep is often called Slow Wave Sleep (SWS). During this stage HGH is released, blood rushes from the brain to the muscles to initiate recovery and re-energize your body. Additionally, elements of the parasympathetic nervous system are triggered while the sympathetic nervous system is suppressed. All of this supports immune function and normal glucose metabolism during the day.
Stage 4 – Otherwise known as REM sleep, this is the stage where we dream. Our arms and legs are paralyzed, and this is the only stage of sleep where the body doesn’t actually move. This stage of sleep is associated with learning and memory retention, where the hippocampus transfers and filters the day’s information to the neo-cortex, kind of like a computer uploading information and clearing it’s RAM onto a hard drive. During the first few cycles deep sleep periods are longer and REM periods are shorter, but after the 4th cycle the REM periods become much longer and the deep sleep phases much shorter.
QMRHistory of Embryology
https://wikiislam.net/wiki/History_of_Embryology
I discussed in my books that there is actually four stages in embryos and that there are four parts of the embryo the fourth being the neural crest (the different part)
Hippocrates said there were four stages of the embryo
460-370 BC Hippocrates 1st stage: "Sperm is a product which comes from the whole body of each parent, weak sperm coming from the weak parts, and strong sperm from the strong parts."[4]
2nd stage: "The seed (embryo), then, is contained in a membrane ... Moreover, it grows because of its mother's blood, which descends to the womb. For once a woman conceives, she ceases to menstruate..."[5] 3rd stage: "At this stage, with the descent and coagulation of the mother's blood, flesh begins to be formed, with the umbilicus."[6]
4th stage: "As the flesh grows it is formed into distinct members by breath ... The bones grow hard ... moreover they send out branches like a tree ..."[7]
129-210 AD Claudius Galenus "let us divide the creation of the foetus overall into four periods of time.
The first is that in which. as is seen both in abortions and in dissection, the form of the semen prevails [Arabic nutfah]. At this time, Hippocrates too, the all-marvelous, does not yet call the conformation of the animal a foetus; as we heard just now in the case of semen voided in the sixth day, he still calls it semen. But when it has been filled with blood [Arabic alaqa], and heart, brain and liver are still unarticulated and unshaped yet have by now a certain solidarity and considerable size,
this is the second period; the substance of the foetus has the form of flesh and no longer the form of semen. Accordingly you would find that Hippocrates too no longer calls such a form semen but, as was said, foetus.
The third period follows on this, when, as was said, it is possible to see the three ruling parts clearly and a kind of outline, a silhouette, as it were, of all the other parts [Arabic mudghah]. You will see the conformation of the three ruling parts more clearly, that of the parts of the stomach more dimly, and much more still, that of the limbs. Later on they form "twigs", as Hippocrates expressed it, indicating by the term their similarity to branches.
The fourth and final period is at the stage when all the parts in the limbs have been differentiated; and at this part Hippocrates the marvelous no longer calls the foetus an embryo only, but already a child, too when he says that it jerks and moves as an animal now fully formed."[11]
"... The time has come for nature to articulate the organs precisely and to bring all the parts to completion. Thus it caused flesh to grow on and around all the bones, and at the same time ... it made at the ends of the bones ligaments that bind them to each other, and along their entire length it placed around them on all sides thin membranes, called periosteal, on which it caused flesh to grow."[12]
ca. 200 AD Talmud (Jewish text) The embryo was called peri habbetten (fruit of the body) and develops as:
1. golem (formless, rolled-up thing);
2. shefir meruqqam (embroidered foetus - shefir means amniotic sac);
3. 'ubbar (something carried); v'alad (child); v'alad shel qayama (noble or viable child) and
4. ben she-kallu chadashav (child whose months have been completed).[13
FOUR LOBES OF THE LIVER
https://en.wikipedia.org/wiki/Liver
https://en.wikipedia.org/wiki/File:Sobo_1906_389.png
The liver is a reddish-brown wedge-shaped organ with four lobes of unequal size and shape. A human liver normally weighs 1.44–1.66 kg (3.2–3.7 lb).[9] It is both the heaviest internal organ and the largest gland in the human body. Located in the right upper quadrant of the abdominal cavity, it rests just below the diaphragm, to the right of the stomach and overlies the gallbladder.[4]
Other anatomical landmarks exist, such as the ligamentum venosum and the round ligament of the liver (ligamentum teres), which further divide the left side of the liver in two sections. An important anatomical landmark, the porta hepatis, also known as the transverse fissure of the liver, divides this left portion into four segments, which can be numbered starting at the caudate lobe as I in an anticlockwise manner. From this visceral view, seven segments can be seen, because the eighth segment is only visible in the parietal view.[15]
FOUR CHAMBERS OF HEART
https://en.wikipedia.org/wiki/Circulatory_system#Cardiovascular_system
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle
FOUR TYPES OF BEHAVIOR
https://en.wikipedia.org/wiki/Ethology
Several animal species, including humans, tend to live in groups. Group size is a major aspect of their social environment. Social life is probably a complex and effective survival strategy. It may be regarded as a sort of symbiosis among individuals of the same species: a society is composed of a group of individuals belonging to the same species living within well-defined rules on food management, role assignments and reciprocal dependence.
When biologists interested in evolution theory first started examining social behaviour, some apparently unanswerable questions arose, such as how the birth of sterile castes, like in bees, could be explained through an evolving mechanism that emphasizes the reproductive success of as many individuals as possible, or why, amongst animals living in small groups like squirrels, an individual would risk its own life to save the rest of the group. These behaviours may be examples of altruism.[34] Of course, not all behaviours are altruistic, as indicated by the table below. For example, revengeful behaviour was at one point claimed to have been observed exclusively in Homo sapiens. However, other species have been reported to be vengeful including chimpanzees,[35] as well as anecdotal reports of vengeful camels.[36]
Classification of social behaviours
Type of behaviour Effect on the donor Effect on the receiver
Egoistic Increases fitness Decreases fitness
Cooperative Increases fitness Increases fitness
Altruistic Decreases fitness Increases fitness
Revengeful Decreases fitness Decreases fitness
http://www.kidsdiscover.com/infographics/infographic-carbon-hydrogen-oxygen-and-nitrogen/
Four elements make up most living things — including you! The elements are carbon, hydrogen, oxygen, and nitrogen. Download this free lesson sheet and help give kids an understanding of these four essential elements and their basic attributes.
http://1.bp.blogspot.com/-X6ortdOKUfw/UiEF74-S1pI/AAAAAAAAA2g/ZfEcvPm6_is/s1600/josh_crn_8.png
NOTICE HOW THE THIRD, NITROGEN, IS DIFFERENT
One of the first things learned in biology class in college is the amino acid structure. Amino acids are the building blocks of proteins. The structure consists of four parts. They are
Square 1: the H group
Square 2: the Amino group
Square 3: the Carboxyl group
Square 4: the R group
In the first few weeks of biology class in college the professors also teach the levels of protein structure. The levels fit the quadrant model pattern. They are
Square 1: The primary structure. The primary structure of a protein is the linear sequence of amino acids in the polypeptide chain. The primary structure is held together by covalent bonds such as peptide bonds.
Square 2: The secondary structure. Secondary structure is highly regular local sub-structures on the polypeptide backbone chain. Two main types of secondary structure are the alpha helix and the beta strand or beta sheets.
Square 3: The tertiary structure. Tertiary structure is a three-dimensional structure of monomeric and multimeric protein molecules. The alpha-helixes and beta pleated-sheets are folded into a compact globular structure. The third square is always more solid and more physical. That is the nature of the territory structure.
Square 4: Quaternary structure. Quaternary structure is the three-dimensional structure of a multi-subunit protein and how the subunits fit together. Quaternary structure is stabilized by the same non-covalent interactions and disulfide bonds as the tertiary structure. Complexes of two or more polypeptides (i.e. multiple subunits) are called multimers.
https://en.wikipedia.org/wiki/Amino_acid
FOUR GROUPS AMINO ACIDS
Amino acids are usually classified by the properties of their side-chain into four groups. The side-chain can make an amino acid a weak acid or a weak base, and a hydrophile if the side-chain is polar or a hydrophobe if it is nonpolar.[34] The chemical structures of the 22 standard amino acids, along with their chemical properties, are described more fully in the article on these proteinogenic amino acids.
22 amino acids like 22 letters of Hebrew Alphabet
http://www.chemicalconnection.org.uk/chemistry/topics/view.php?topic=5&headingno=6
Proteins are much more complicated than just a chain of amino-acids because proteins fold spontaneously depending on the R groups in their amino-acid sequence. The structure of proteins is very important for their function. The protein folding process can be divided up into four stages, which we can think of as stages in putting together a book:
Primary structure: a chain of amino-acids joined together (letters coming together to form words)
Secondary structure: the chains fold into sheets or coils (sentences)
Tertiary structure: the sheets or coils fold in on one another (chapters of a book) 4. Quaternary structure: amino-acid chains folded in their tertiary structure interact with one another to give the final functional protein (e.g. haemoglobin has 4 chains) (a book)
THE GENETIC CODE TABLE IS A 16 SQUARE QUADRANT MODEL
https://arxiv.org/pdf/1107.1998.pdf
Figure 3. The standard Genetic Code Table with designation of four diversity types of protein amino acids and corresponding codons: first and second type without color (in light and dark tones, respectively), but third and forth in color. The codon number: first 08, second 17, third 10 and fourth 26 [just as in algebraic system in Solution (4.2)]. The roman numbers designate class I and class II of aminoacyl-tRNA synthetases as in Table E3. The details see in the text.
http://www.monarch-butterfly.com
THE MONARCH BUTTERFLY HAS FOUR MIGRATIONS- THE FOURTH IS DIFFERENT FROM THE PREVIOUS THREE
Here is an excerpt from my book QMR
The monarch butterfly is considered the king of the butterflies, and the phenomena associated with the monarch butterfly fit the quadrant model pattern. Monarch butterflies go through four stages during one life cycle. They are
Square 1: the egg
Square 2: the larvae (caterpillar)
Square 3: the pupa (chrysalis)
Square 4: the adult butterfly (the transformation)
The life cycles of the Monarch butterfly are four generations. They fit the quadrant model pattern. They are
Square 1: in March and April eggs are laid in milkweed plants. The monarch butterflies that are born live for two to six weeks. and lay eggs
Square 2: in May and June the same the Monarch butterflies do the same thing as square 1.
Square 3: in July and August the Monarch butterflies do the same thing as square 1 and 2.
Square 4: The fourth generation is born in September and October and goes through exactly the same process as the first, second and third generations except for one part. The fourth generation of monarch butterflies does not die after two to six weeks. Instead, this generation of monarch butterflies migrates to warmer climates like Mexico and California and will live for six to eight months until it is time to start the whole process over again. The fourth square is always different from the previous three squares. The life of the Monarch butterfly reveals the quadrant model pattern. The first three are the same and almost identical. The fourth has a transcendent quality to it.
FOUR STAGE MODEL
https://en.wikipedia.org/wiki/Human_sexual_response_cycle
The human sexual response cycle is a FOUR-stage model of physiological responses to sexual stimulation,[1] which, in order of their occurrence, are the excitement phase, plateau phase, orgasmic phase, and resolution phase. The cycle was first proposed by William H. Masters and Virginia E. Johnson in their 1966 book Human Sexual Response.[1][2] Since then, other human sexual response models have been formulated.
Excitement phase[edit]
The excitement phase (also known as the arousal phase or initial excitement phase) is the first stage of the human sexual response cycle. It occurs as the result of physical or mental erotic stimuli, such as kissing, petting, or viewing erotic images, that leads to sexual arousal. During the excitement stage, the body prepares for sexual intercourse, initially leading to the plateau phase.[1] There is wide socio-cultural variation regarding preferences for the length of foreplay and the stimulation methods used.[citation needed] Physical and emotional interaction and stimulation of the erogenous zones during foreplay usually establishes at least some initial arousal.[citation needed]
Excitement in both sexes[edit]
See also: Flushing (physiology)
Among both sexes, the excitement phase results in an increase in heart rate, breathing rate, and a rise in blood pressure.[1] A survey in 2006 has found that sexual arousal in about 82% of young females and 52% of young males arises or is enhanced by direct stimulation of nipples, with only 7–8% reporting that it decreased their arousal.[3] Vasocongestion of the skin, commonly referred to as the sex flush, will occur in approximately 50-75% of females and 25% of males. The sex flush tends to occur more often under warmer conditions and may not appear at all under cooler temperatures.
During the female sex flush, pinkish spots develop under the breasts, then spread to the breasts, torso, face, hands, soles of the feet, and possibly over the entire body.[1] Vasocongestion is also responsible for the darkening of the clitoris and the walls of the vagina during sexual arousal. During the male sex flush, the coloration of the skin develops less consistently than in the female, but typically starts with the epigastrium (upper abdomen), spreads across the chest, then continues to the neck, face, forehead, back, and sometimes, shoulders and forearms. The sex flush typically disappears soon after orgasm occurs, but this may take up to two hours or so and, sometimes, intense sweating will occur simultaneously. The flush usually diminishes in reverse of the order in which it appeared.[2]
An increase in muscle tone (myotonia) of certain muscle groups, occurring voluntarily and involuntarily, begins during this phase among both sexes. Also, the external anal sphincter may contract randomly upon contact (or later during orgasm without contact).
Excitement in males[edit]
In males, the beginning of the excitement phase is observed when the penis becomes partially erect, often after only a few seconds of erotic stimulation.[1] The erection may be partially lost and regained repeatedly during an extended excitement phase. Both testicles become drawn upward toward the perineum, notably in circumcised males where less skin is available to accommodate the erection. Also, the scrotum can tense and thicken during the erection process.
Excitement in females[edit]
In females, the excitement phase can last from several minutes to several hours. The onset of vasocongestion results in swelling of the woman's clitoris, labia minora and vagina. The muscle that surrounds the vaginal opening grows tighter and the uterus elevates and grows in size. The vaginal walls begin to produce a lubricating organic[clarification needed] liquid.[1] Meanwhile, the breasts increase slightly in size and nipples become hardened and erect.
Plateau phase[edit]
The plateau phase is the period of sexual excitement prior to orgasm. The phase is characterised by an increased circulation and heart rate in both sexes, increased sexual pleasure with increased stimulation, and further increased muscle tension. Also, respiration continues at an elevated level.[1] Both men and women may also begin to vocalize involuntarily at this stage. Prolonged time in the plateau phase without progression to the orgasmic phase may result in frustration if continued for too long (see orgasm control).
Plateau in males[edit]
During this phase, the male urethral sphincter contracts (so as to prevent urine from mixing with semen, and to guard against retrograde ejaculation) and muscles at the base of the penis begin a steady rhythmic contraction.[1] Males may start to secrete seminal fluid or pre-ejaculatory fluid and the testicles rise closer to the body.[2]
Plateau in females[edit]
The plateau stage in females is basically a continuation of the same changes evident in the excitement stage. The clitoris becomes extremely sensitive and withdraws slightly and the Bartholin glands produce further lubrication. The tissues of the outer third of the vagina swell, and the pubococcygeus muscle tightens, reducing the diameter of the opening of the vagina.[1] Masters and Johnson refer to the changes that take place during the plateau stage as the orgasmic platform. For those who never achieve orgasm, this is the peak of sexual excitement.
Orgasmic phase[edit]
Main article: Orgasm
Orgasm is the conclusion of the plateau phase of the sexual response cycle and is experienced by both males and females. It is accompanied by quick cycles of muscle contraction in the lower pelvic muscles, which surround both the anus and the primary sexual organs. Women also experience uterine and vaginal contractions. Orgasms are often associated with other involuntary actions, including vocalizations and muscular spasms in other areas of the body, and a generally euphoric sensation. Heart rate is increased even further.[1]
Orgasm in males[edit]
In men, orgasm is usually associated with ejaculation. Each ejection is accompanied with continuous pulses of sexual pleasure, especially in the penis and loins.[1] Other sensations may be felt strongly among the lower spine, or lower back. The first and second convulsions are usually the most intense in sensation, and produce the greatest quantity of semen. Thereafter, each contraction is associated with a diminishing volume of semen and a milder sensation of pleasure.[1]
Orgasm in females[edit]
Orgasms in females can vary widely from woman to woman. The overall sensation is similar to that of the male orgasm. They are commonly associated with an increase in vaginal lubrication, a tightening of the vaginal walls, and overall pleasure.[1]
Resolution phase[edit]
Main article: Refractory period (sex)
The resolution phase occurs after orgasm and allows the muscles to relax, blood pressure to drop and the body to slow down from its excited state.[1] The refractory period, which is part of the resolution phase, is the time frame in which usually a man is unable to orgasm again, though women can also experience a refractory period.
Resolution in males[edit]
Masters and Johnson described the two-stage detumescence of the penis: In the first stage, the penis decreases from its erect state to about fifty percent larger than its flaccid state. This occurs during the refractory period. In the second stage (and after the refractory period is finished), the penis decreases in size and returns to being flaccid.[2] It is generally impossible for men to achieve orgasm during the refractory period.[2][4][5] Masters and Johnson argue that this period must end before men can become aroused again.[6]
Resolution in females[edit]
According to Masters and Johnson, women have the ability to orgasm again very quickly, as long as they have effective stimulation. As a result, they are able to have multiple orgasms in a relatively short period of time.[2][6] Though generally reported that women do not experience a refractory period and thus can experience an additional orgasm, or multiple orgasms, soon after the first,[4][5] some sources state that men and women experience a refractory period because women may also experience a period after orgasm in which further sexual stimulation does not produce excitement.[7][8] For some women, the clitoris is very sensitive after climax, making additional stimulation initially painful.[9] After the initial orgasm, subsequent orgasms for women may also be stronger or more pleasurable as the stimulation accumulates.[9]
https://en.wikipedia.org/wiki/Stomach
Here is another excerpt from my book the quadrant model of reality.
The layers of the stomach and gastrointestinal tract represent the quadrant model pattern. They are
Square 1: the mucosa layer. This layer sort of helps against pathogens. The first square is kind of a protective square, representing the idealist.
Square 2: the submucosa layer. The first two squares are the duality. This layer is made of connective tissue and kind of holds things together. The second square is homeostasis.
Square 3: the muscular layer. The third square is the doing square. This is the part of the digestive system that contracts that allows the food to pass through.
Square 4: serous membrane. The fourth square is different from the previous three.
Here is another excerpt from my book the quadrant model of reality.
The layers of the stomach and gastrointestinal tract represent the quadrant model pattern. They are
Square 1: the mucosa layer. This layer sort of helps against pathogens. The first square is kind of a protective square, representing the idealist.
Square 2: the submucosa layer. The first two squares are the duality. This layer is made of connective tissue and kind of holds things together. The second square is homeostasis.
Square 3: the muscular layer. The third square is the doing square. This is the part of the digestive system that contracts that allows the food to pass through.
Square 4: serous membrane. The fourth square is different from the previous three.
http://www.institute4learning.com/…/the-four-stages-of-bir…/
Eighty years ago, Austrian psychoanalyst Otto Rank theorized that when we are born, we experience a “birth trauma” that affects us for the rest of our lives. More recently, psychiatrist Stanislav Grof has created a model for understanding in greater depth the kinds of effects that birth can have upon our later lives. He writes that there are four distinct stages of birth, or what he calls Basic Perinatal Matrices (BPM) that give rise to different kinds of traumas (as well as positive experiences), and that have different types of effects upon our future development.
Basic Perinatal Matrix I (BPM I)represents that point in the birth process when labor has not yet started and we are still fully inside of the mother’s uterus. This can be a “good womb” or “bad womb” situation (or a combination of both), depending upon the circumstances. Stress hormones from our mothers might create anxiety in utero and/or nurturing hormones could create pleasant feelings. The surrealist artist Salvador Dali wrote in his autobiography that his own bad womb experience (his parents were in despair over the death of his brother at the time) haunted him for the rest of his life.
Basic Perinatal Matrix II (BPM II) is that point in the birth when labor has started and we are being pushed up against the cervix by the mother’s contractions but the cervix has not yet begun to dilate or open. This can be a very scary experience, and people in later life who were traumatized at this point in their birth may feel claustrophobia, existential angst, depression, feelings of terror, or other negative consequences. Edgar Allen Poe may have been a BPM II baby as evidenced by his short story “The Pit and the Pendulum” where a character finds himself in a prison where walls are closing in on him and the only way out is down a bottomless pit.
Basic Perinatal Matrix III (BPM III) is when the cervix has opened and we start to move out (or push out) through the birth canal. This can be both thrilling and also violent or dangerous (for example, the umbilical cord might strangle the fetus at this point). People who get fixated at this point in their births may grow up to become thrill-seekers, but also potentially dangerous individuals. Adolf Hitler may have been a BPM III baby with his violent policies and his fixation on strangulation (he often had his enemies strangled).
The final stage of birth, Basic Perinatal Matrix IV (BPM IV) is when we have left the womb and are now outside in the world. This stage may be associated in later life with feelings of expansion (possibly even agoraphobia), feelings of rebirth (perhaps associated with religious experiences), and also feelings of separation and loneliness. People who have undergone dramatic religious conversions, such as the French philosopher Blaise Pascal or the Apostle Paul of Tarsus, may have re-experienced this stage of birth during their spiritual transformations in adulthood.
Grof originally discovered the presence of these four basic perinatal matrices when using psychedelic (LSD) therapy with patients suffering from mental disorders in Europe and the United States (he was the Chief of Psychiatric Research at the Maryland Psychiatric Research Center in the late 1960’s and early 1970’s). He is currently using a method he developed called Holotropic Breathwork that both reveals and heals the traumas associated with these basic perinatal matrices (as well as experiences associated with other stages of development such as early childhood). To find out more about Grof’s birth model, or other aspects of his important work, see the following resources:
https://en.wikipedia.org/wiki/Miller–Urey_experiment
The Miller Urey experiement was an unprecedented experiment in origins of life research, which demonstrated that amino acids, which are necessary to create DNA and life, could be produced with the combination of just four natural components. These components were
Square 1: water
Square 2: methane
Square 3: ammonia
Square 4: hydrogen
If these four components were put in a steel flask, and lighting was added (the fifth component; the fifth square is representative of God and light is related with God), then amino acids would generate. It was thought that this experiment could prove that there may have been a "natural" genesis of life on Earth.
FOUR MAJOR TISSUES MAKE UP THE TOOTH
https://en.wikipedia.org/wiki/Human_tooth
Enamel[edit]
Main article: Tooth enamel
Enamel is the hardest and most highly mineralized substance of the body. It is one of the four major tissues which make up the tooth, along with dentin, cementum, and dental pulp.[7] It is normally visible and must be supported by underlying dentin. 96% of enamel consists of mineral, with water and organic material comprising the rest.[8] The normal color of enamel varies from light yellow to grayish white. At the edges of teeth where there is no dentin underlying the enamel, the color sometimes has a slightly blue tone. Since enamel is semitranslucent, the color of dentin and any restorative dental material underneath the enamel strongly affects the appearance of a tooth. Enamel varies in thickness over the surface of the tooth and is often thickest at the cusp, up to 2.5mm, and thinnest at its border, which is seen clinically as the CEJ.[9] The wear rate of enamel, called attrition, is 8 micrometers a year from normal factors.[citation needed]
Enamel's primary mineral is hydroxyapatite, which is a crystalline calcium phosphate.[10] The large amount of minerals in enamel accounts not only for its strength but also for its brittleness.[9] Dentin, which is less mineralized and less brittle, compensates for enamel and is necessary as a support.[10] Unlike dentin and bone, enamel does not contain collagen. Proteins of note in the development of enamel are ameloblastins, amelogenins, enamelins and tuftelins. It is believed that they aid in the development of enamel by serving as framework support, among other functions.[11]
Dentin[edit]
Main article: Dentin
Dentin is the substance between enamel or cementum and the pulp chamber. It is secreted by the odontoblasts of the dental pulp.[12] The formation of dentin is known as dentinogenesis. The porous, yellow-hued material is made up of 70% inorganic materials, 20% organic materials, and 10% water by weight.[13] Because it is softer than enamel, it decays more rapidly and is subject to severe cavities if not properly treated, but dentin still acts as a protective layer and supports the crown of the tooth.
Dentin is a mineralized connective tissue with an organic matrix of collagenous proteins. Dentin has microscopic channels, called dentinal tubules, which radiate outward through the dentin from the pulp cavity to the exterior cementum or enamel border.[14] The diameter of these tubules range from 2.5 μm near the pulp, to 1.2 μm in the midportion, and 900 nm near the dentino-enamel junction.[15] Although they may have tiny side-branches, the tubules do not intersect with each other. Their length is dictated by the radius of the tooth. The three dimensional configuration of the dentinal tubules is genetically determined.
Cementum[edit]
Main article: Cementum
Cementum is a specialized bone like substance covering the root of a tooth.[12] It is approximately 45% inorganic material (mainly hydroxyapatite), 33% organic material (mainly collagen) and 22% water. Cementum is excreted by cementoblasts within the root of the tooth and is thickest at the root apex. Its coloration is yellowish and it is softer than dentin and enamel. The principal role of cementum is to serve as a medium by which the periodontal ligaments can attach to the tooth for stability. At the cementoenamel junction, the cementum is acellular due to its lack of cellular components, and this acellular type covers at least ⅔ of the root.[16] The more permeable form of cementum, cellular cementum, covers about ⅓ of the root apex.[17]
Dental Pulp[edit]
Main article: Pulp (tooth)
The dental pulp is the central part of the tooth filled with soft connective tissue.[13] This tissue contains blood vessels and nerves that enter the tooth from a hole at the apex of the root.[18] Along the border between the dentin and the pulp are odontoblasts, which initiate the formation of dentin.[13] Other cells in the pulp include fibroblasts, preodontoblasts, macrophages and T lymphocytes.[19] The pulp is commonly called "the nerve" of the tooth.
FOUR HORNS
http://listverse.com/2010/10/01/10-spectacular-horned-dinosaurs/
Diabloceratops means “devil horned face”. Its spectacular remains were found in Utah. It had a very small nasal horn, but its brow horns were quite large, and the ones in top of the frill were even larger. These four horns, along with the forward-curving frill, gave this animal a strange appearance, different from all other horned dinosaurs known. Diabloceratops seems to be a primitive horned dinosaur, since it shares some anatomical traits with the protoceratopsids, a closely related but less advanced family. Its jaws were massive, which suggests that its bite was very powerful. The same is true for most other ceratopsians and it is possible that many species used their huge beaks as much as their horns, as weapons against predators.
http://www.kashrut.com/articles/buffalo/
For the purpose of identifying kosher animals, the Shulchan Aruch (Yoreh De'ah 79, 80, 82-85), based on Leviticus 11:1-27 and Deuteronomy 14:3-20, divides the animal kingdom into five categories, four of which have kosher members. The categories with kosher members are: terrestrial mammalian quadrupeds, fish, birds, and invertebrates. The fifth category - bugs - has no kosher members. In addition, all creatures that do not fit into one of the above categories, such as all reptiles and amphibians, are not kosher. For each of the four categories with kosher members, the Torah specifies a means to indicate whether a particular species is kosher, and in many cases the rabbis clarified, elaborated, embellished, and added to the indicators.
The Torah further enumerates four non-kosher animals which have only one kosher sign. Among these are the pig, which has split hooves but does not chew its cud, and the camel, which chews its cud but does not have split hooves.5
There are four types of animal that can legitimately be called buffalo.10 The European bison (Bison bonasus), also known as a wisent, is the most closely related to the American bison. The Asiatic water buffalo (Bubalus arnee or Bubalus bubalis) of which there are four subspecies and is native to South Asia, India, Nepal, sri Lanka, and Borneo was probably well-known to ancient rabbinic Jewish authorities. The African buffalo (Syncerus caffer) has three subspecies and, as its name applies, is native to Africa, in general sub-Saharan.
The American "buffalo" can obviously not be found in any of the earlier literature and hence presents its own dilemma. It would seem that according to the Shulchan Aruch (YD 79:1) no mesorah (tradition)16 is required to establish that a specific mammalian quadruped is kosher - it simply needs to possess the requisite physical characteristics of chewing its cud and having fully split hooves - characteristics which all four "buffalos", including the American bison, possess. The Pri Maggadim (Siftei Da'at, YD 80:1), Kaf haChaim (80:5), and Pitchei T'shuva (YD:80:1) all state explicitly that the physical indicia are sufficient to establish a species as kosher.
The debate about a need for a mesorah does not seem applicable to the buffalo question, and for a variety of reasons it appears that all four "buffalos," and most certainly the water buffalo and the American bison, are kosher. There is not yet a stampede for kosher buffalo, but based on my informal survey of several cities it certainly appears that there is some desire for it. I do not know how the major kashrut organizations would rule in a case where there was truly a need for a mesorah according to the Chazon Ish and none existed. To my knowledge there are no other recent responsa that address this Pri Maggadim vs. Chazon Ish dispute.
https://en.wikipedia.org/wiki/Piranha
Traditionally, only the four genera Pristobrycon, Pygocentrus, Pygopristis, and Serrasalmus are considered to be true piranhas, due to their specialized teeth.
FOUR SPECIES
https://en.wikipedia.org/wiki/Pygocentrus
Pygocentrus is a genus of the piranha family Serrasalmidae. All species are native to tropical and subtropical South America. All the species are predatory, scavengers and form huge schools. The famous red-bellied piranha, Pygocentrus nattereri, is one of four species in the genus. The Chi-Cohala[spelling?] tribe uses the teeth to make tools and weapons.
Species[edit]
There are currently four recognized species in this genus:[1]
Pygocentrus cariba (Humboldt, 1821) (black spot piranha) – Orinoco river basin.
Pygocentrus nattereri Kner, 1858 (red piranha, red-bellied piranha) – Amazon, Paraguay-Paraná-Uruguay, and Essequibo river basins, as well as various river in northeastern Brazil.
Pygocentrus palometa Valenciennes, 1850 – Orinoco river basin, possibly a nomen dubium.[2]
Pygocentrus piraya (G. Cuvier, 1819) (San Francisco piranha) – São Francisco River
https://en.wikipedia.org/wiki/Foureye_butterflyfish
The foureye butterflyfish (Chaetodon capistratus) is a butterflyfish (family Chaetodontidae). It is alternatively called the four-eyed butterflyfish. This species is found in the Western Atlantic from Massachusetts, USA and Bermuda to the West Indies and northern South America.[1]
https://en.wikipedia.org/wiki/Teleost
Teleosts have four major life stages: the egg, the larva, the juvenile and the adult
THE FOURTH IS DIFFERENT- FOUR CLADES
https://en.wikipedia.org/wiki/Bryophyte
The three bryophyte clades are the Divisions Marchantiophyta (liverworts), Bryophyta (mosses) and Anthocerotophyta (hornworts).[11] The vascular plants or tracheophytes form a fourth, unranked clade of land plants called the "Polysporangiophyta".
FOUR CLASSES OF FERNS
https://en.wikipedia.org/wiki/Fern
The 2006 paper by Smith et al. proposed a classification, based on phylogeny, that divided extant ferns into four classes:
Psilotopsida (Whisk Ferns and Ophioglossoid Ferns), about 92 species[12]
Equisetopsida (Horsetails), about 15 species[12]
Marattiopsida, about 150 species[12]
Polypodiopsida (Leptosporangiate Ferns), over 9,000 species[12]
THE FOUR EUKARYOTIC KINGDOMS- THE FOURTH TRANSCENDS THE PREVIOUS THREE
http://www.ucmp.berkeley.edu/archaea/archaea.html
At a more fundamental level, a distinction was made between the prokaryotic bacteria and the four eukaryotic kingdoms (plants, animals, fungi, & protists).
FOURTH STAGE DIFFERENT
https://en.wikipedia.org/wiki/Anopheles
Like all mosquitoes, anophelines go through four stages in their life cycles: egg, larva, pupa, and imago. The first three stages are aquatic and together last 5–14 days, depending on the species and the ambient temperature.
FOUR GROUPS
https://en.wikipedia.org/wiki/Schistosoma
The genus Schistosoma as currently[when?] defined is paraphyletic,[citation needed] so revisions are likely. Over twenty species are recognised within this genus.
The genus has been divided[citation needed] into four groups — indicum, japonicum, haematobium and mansoni. The affinities of the remaining species are still being clarified.
FOUR SUBORDERS
https://en.wikipedia.org/wiki/Eel
An eel is any fish belonging to the order Anguilliformes (/æŋˌɡwɪlᵻˈfɔːrmiːz/), which consists of four suborders, 20 families, 111 genera and about 800 species.
16 SPECIES 16 SQUARES QMR AND ALSO FOUR EYED
https://en.wikipedia.org/wiki/Anablepidae
Anablepidae is a family of freshwater and brackish water fishes living in brackish and freshwater habitats from southern Mexico to southern South America.[1] There are three genera with sixteen species: the four-eyed fishes (genus Anableps), the onesided livebearers (genus Jenynsia) and the white-eye, Oxyzygonectes dovii. Fish of this family eat mostly insects and other invertebrates.
FISH JAWS ARE FOUR BAR LINKAGES
https://en.wikipedia.org/wiki/Fish_jaw
Their largest species, Dunkleosteus terrelli, measured up to 10 m (33 ft)[45][46] and weighed 3.6 t (4.0 short tons).[47] It possessed a four bar linkage mechanism for jaw opening that incorporated connections between the skull, the thoracic shield, the lower jaw and the jaw muscles joined together by movable joints
Human genes[edit]
Humans have Hox genes in four clusters: [27]
https://en.wikipedia.org/wiki/Hox_gene
Cluster Chromosome Genes
HOXA chromosome 7 HOXA1, HOXA2, HOXA3, HOXA4, HOXA5, HOXA6, HOXA7, HOXA9, HOXA10, HOXA11, HOXA13
HOXB chromosome 17 HOXB1, HOXB2, HOXB3, HOXB4, HOXB5, HOXB6, HOXB7, HOXB8, HOXB9, HOXB13
HOXC chromosome 12 HOXC4, HOXC5, HOXC6, HOXC8, HOXC9, HOXC10, HOXC11, HOXC12, HOXC13
HOXD chromosome 2 HOXD1, HOXD3, HOXD4, HOXD8, HOXD9, HOXD10, HOXD11, HOXD12, HOXD13
Four races- FOUR RACES
https://en.wikipedia.org/wiki/Carl_Linnaeus
See also: Race (human categorisation)
In the first edition of Systema Naturae, Linnaeus subdivided the human species into four varieties based on continent and skin colour: "Europæus albus" (white European), "Americanus rubescens" (red American), "Asiaticus fuscus" (brown Asian) and "Africanus Niger" (black African). In the tenth edition of Systema Naturae he further detailed stereotypical characteristics for each variety, based on the concept of the four temperaments from classical antiquity, and changed the description of Asians' skin tone to "luridus" (yellow).[176][177][178][179][180] Additionally, Linnaeus created a wastebasket taxon "monstrosus" for "wild and monstrous humans, unknown groups, and more or less abnormal people".[181]
FOUR HEART SOUNDS
https://en.wikipedia.org/wiki/Fourth_heart_sound
Fourth heart sound
From Wikipedia, the free encyclopedia
Fourth heart sound
Classification and external resources
ICD-9-CM 427.9, 785.3
DiseasesDB 4938
[edit on Wikidata]
Diagram of the heart.
The fourth heart sound or S4 is an extra heart sound that occurs during late diastole, immediately before the normal two "lub-dub" heart sounds (S1 and S2). It occurs just after atrial contraction and immediately before the systolic S1 and is caused by the atria contracting forcefully in an effort to overcome an abnormally stiff or hypertrophic ventricle.
This produces a rhythm classically compared to the cadence of the word "Tennessee".[1][2] One can also use the phrase "A-stiff-wall" to help with the cadence (a S4, stiff S1, wall S2), as well as the pathology of the S4 sound.[3]
FOUR ORDERS
https://en.wikipedia.org/wiki/Glomeromycota
Nowadays it is accepted that Glomeromycota consists of 4 orders.[17]
Glomeromycota
Diversisporales
Glomerales
Archaeosporales
Paraglomerales
TETRA IS FOUR
https://en.wikipedia.org/wiki/Evolutionary_history_of_plants
Heterosporic plants, as their name suggests, bear spores of two sizes – microspores and megaspores. These would germinate to form microgametophytes and megagametophytes, respectively. This system paved the way for ovules and seeds: taken to the extreme, the megasporangia could bear only a single megaspore tetrad, and to complete the transition to true ovules, three of the megaspores in the original tetrad could be aborted, leaving one megaspore per megasporangium.
FOUR TYPES OF ASCUS FOUR CELLS
Asci, notably those of Neurospora crassa, have been used in laboratories for studying the process of meiosis, because the four cells produced by meiosis line up in regular order
https://en.wikipedia.org/wiki/Ascus
The form of the ascus, the capsule which contains the sexual spores, is important for classification of the Ascomycota. There are four basic types of ascus.
A unitunicate-operculate ascus has a "lid", the Operculum, which breaks open when the spores are mature and allows the spores to escape. Unitunicate-operculate asci only occur in those ascocarps which have apothecia, for instance the morels. 'Unitunicate' means 'single-walled'.
Instead of an operculum, a unitunicate-inoperculate ascus has an elastic ring that functions like a pressure valve. Once mature the elastic ring briefly expands and lets the spores shoot out. This type appears both in apothecia and in perithecia; an example is the illustrated Hypomyces chrysospermus.
Ascus of Saccharomyces cerevisiae containing a tetrad of four spores
A bitunicate ascus is enclosed in a double wall. This consists of a thin, brittle outer shell and a thick elastic inner wall. When the spores are mature, the shell splits open so that the inner wall can take up water. As a consequence this begins to extend with its spores until it protrudes above the rest of the ascocarp so that the spores can escape into free air without being obstructed by the bulk of the fruiting body. Bitunicate asci occur only in pseudothecia and are found only in the classes Dothideomycetes and Chaetothyriomycetes (which were formerly united in the old class Loculoascomycetes). Examples: Venturia inaequalis (apple scab) and Guignardia aesculi (Brown Leaf Mold of Horse Chestnut).
Prototunicate asci are mostly spherical in shape and they have no active dispersal mechanism at all. The mature ascus wall dissolves allowing the spores to escape, or it is broken open by other influences, such as animals. Asci of this type can be found both in perithecia and in cleistothecia, for instance with Dutch elm disease (Ophiostoma). This is something of a catch-all term for cases which do not fit into the other three ascus types, and they probably belong to several independent groups which evolved separately from unitunicate asci.
TETRAD OF FOUR SPORES
https://en.wikipedia.org/wiki/File:Ascus.gif
Ascus of Saccharomyces cerevisiae containing a tetrad of four spores
TETRA MEANS FOUR
https://en.wikipedia.org/wiki/Tetragonula_iridipennis
Like other bees in its sub-species group, T. iridipennis can be identified by its dark mesoscutum or middle thorax region with four distinct hair bands separated by broad glabrous interspaces
The Indian stingless bee or dammar bee, Tetragonula iridipennis, is a species of bee belonging to the family Apidae, subfamily Apinae.
TETRA IS FOUR TRI IS THREE- THE DYNAMIC BETWEEN FOUR AND THREE
https://en.wikipedia.org/wiki/Trigona_(Tetragonula)
Tetragonula is a subgenera of the genus Trigona. In 1961, Brazilian bee expert, Professor J.S. Moure, first proposed the genus name Tetragonula. It was an effort to improve the classification system by dividing the Trigona stingless bees into 9 smaller subgenera. The subgenus Tetragonula includes about 30 other stingless bee species that are found in Oceania, in countries such as Australia, Indonesia, New Guinea, Malaysia, Thailand, The Philippines, India, Sri Lanka, and The Solomon Islands.
https://en.wikipedia.org/wiki/Alcoholism
Several tools may be used to detect a loss of control of alcohol use. These tools are mostly self-reports in questionnaire form. Another common theme is a score or tally that sums up the general severity of alcohol use.[115]
The CAGE questionnaire, named for its four questions, is one such example that may be used to screen patients quickly in a doctor's office.
Two "yes" responses indicate that the respondent should be investigated further.
The questionnaire asks the following questions:
Have you ever felt you needed to Cut down on your drinking?
Have people Annoyed you by criticizing your drinking?
Have you ever felt Guilty about drinking?
Have you ever felt you needed a drink first thing in the morning (Eye-opener) to steady your nerves or to get rid of a hangover?[116][117]
ROTATOR CUFF IS FOUR MUSCLES
https://en.wikipedia.org/wiki/Shoulder
The rotator cuff is an anatomical term given to the group of four muscles and their tendons that act to stabilize the shoulder.[3] These muscles are the supraspinatus, infraspinatus, teres minor and subscapularis and that hold the head of the humerus in the glenoid cavity during movement.[3] The cuff adheres to the glenohumeral capsule and attaches to the head of the humerus.[3] Together, these keep the humeral head in the glenoid cavity, preventing upward migration of the humeral head caused by the pull of the deltoid muscle at the beginning of arm elevation. The infraspinatus and the teres minor, along with the anterior fibers of the deltoid muscle, are responsible for external rotation of the arm.[5]
The four tendons of these muscles converge to form the rotator cuff tendon. This tendon, along with the articular capsule, the coracohumeral ligament, and the glenohumeral ligament complex, blend into a confluent sheet before insertion into the humeral tuberosities.[6] The infraspinatus and teres minor fuse near their musculotendinous junctions, while the supraspinatus and subscapularis tendons join as a sheath that surrounds the biceps tendon at the entrance of the bicipital groove.[6]
THERE ARE FOUR STRAND DNAS THOUGH IT IS RARE- THE FOURTH IS ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Nucleic_acid
In most cases, naturally occurring DNA molecules are double-stranded and RNA molecules are single-stranded.[20] There are numerous exceptions, however—some viruses have genomes made of double-stranded RNA and other viruses have single-stranded DNA genomes,[21] and, in some circumstances, nucleic acid structures with three or four strands can form.[22]
FOUR PULMONARY VEINS
https://en.wikipedia.org/wiki/Pulmonary_vein
The pulmonary veins are large blood vessels that receive oxygenated blood from the lungs and drain into the left atrium of the heart. There are four pulmonary veins, two from each lung. The pulmonary veins are among the few veins that carry oxygenated blood.
Contents [hide]
1 Structure
1.1 Variation
1.2 Development
2 Function
3 Clinical significance
4 Additional images
5 References
6 See also
7 External links
Structure[edit]
Two pulmonary veins emerge from each lung hilum, receiving blood from three or four bronchial veins apiece and draining into the left atrium. An inferior and superior vein drains each lung, so there are four veins in total.[1] The veins are fixed to the pericardium. The pulmonary veins travel alongside the pulmonary arteries[2]
https://en.wikipedia.org/wiki/Gram-negative_bacteria
Historically, the kingdom Monera was divided into four divisions based on Gram staining: Firmacutes (+), Gracillicutes (−), Mollicutes (0) and Mendocutes (var.).
QUADRIVALENT VACCINE
https://en.wikipedia.org/wiki/Meningitis
A quadrivalent vaccine now exists, which combines four vaccines with the exception of B; immunization with this ACW135Y vaccine is now a visa requirement for taking part in Hajj.
THIS IS CONSIDERED THE STRONGEST ORGANISM IN THE UNIVERSE AND BIOLOGISTS HAVE BEEN USING IT TO TRY TO MAKE LIFE BUT SOME FEAR IT CAN POSSIBLY DESTROY ALL LIFE ON EARTH IF EXPERIMENTS GO WRONG BECAUSE IT IS SO STRONG- I LEARNED ABOUT IT AT UCSD AT THE LIBRARY WHEN A GUY RANDOMLY STARTED TALKING ABOUT IT- I LOOKED IT UP IT IS A TETRAD WITH FOUR CELLS MAKING A QUADRANT- IT IS CALLED CONAN THE BACTERIUM
https://en.wikipedia.org/wiki/Deinococcus_radiodurans
D. radiodurans is a rather large, spherical bacterium, with a diameter of 1.5 to 3.5 µm. Four cells normally stick together, forming a tetrad. The bacteria are easily cultured and do not appear to cause disease.[3] Colonies are smooth, convex, and pink to red in color. The cells stain Gram positive, although its cell envelope is unusual and is reminiscent of the cell walls of Gram negative bacteria.[8]
FOUR
https://www.dartmouth.edu/~rswenson/NeuroSci/chapter_9.html
The hippocampus is an ancient area of cerebral cortex that has three layers. This is located in the medial aspect of the temporal lobe, forming the medial wall of the lateral ventricle in this area. The hippocampus has several parts. The dentate gyrus contains densely packed granule cells. There is a curved area of cortex called the Cornu Ammonis (CA) that is divided into four regions called the CA fields. These are designated as CA1 to CA4. These contain prominent pyramidal cells. The CA fields blend into the adjacent subiculum, which, in turn, is connected to the entorhinal cortex on the parahippocampal gyrus of the temporal lobe.
THE FOUR CA FIELDS- CA4 IS DIFFERENT
https://en.wikipedia.org/wiki/Hippocampus_anatomy
The hippocampus proper is composed of a number of subfields. Though terminology varies among authors, the terms most frequently used are dentate gyrus and the cornu ammonis (literally "Amun's horns", abbreviated CA). The dentate gyrus contains the fascia dentata and the hilus, while the CA is differentiated into fields CA1, CA2, CA3, and CA4.
FOUR FLAVORS
https://en.wikipedia.org/wiki/Cider_apple
Classification of cider apples[edit]
The first director of Long Ashton Research Station, Professor B.T.P. Barker, chose tannin & malic acid percentages in juice to indicate belonging to one of four flavour categories,[2] with the expectation that a balanced flavour in the finished cider would need some juice from a member of each category.
Sweets This group is low acidity (<0.45% = 4.5g/L) and in tannins (<0.2%), e.g. Slack-ma-Girdle.
Sharps This group is high in acidity (>0.45%) and low in tannins (<0.2%), e.g. Crimson King. The high acidity, together with that from the bittersharp group, can add 'bite' to the cider.
Bittersweets This group is low in acidity (<0.45%) and high in tannin (>0.2%), e.g. Brown Snout, Dabinett. The raised levels of tannin, which tastes bitter and is astringent, adds a bitterness to the cider. A certain amount of bitterness is expected in ciders of the West Country style.
Bittersharps This group is high in both acidity (>0.45%) and tannin (>0.2%), e.g. Foxwhelp, Kingston Black.
QUATERNION IS GROUPS OF FOUR
Quaternions[edit]
Further information: Quaternion Eagle
https://en.wikipedia.org/wiki/Imperial_Estate#Quaternions
Typical representation of the quaternions (Anton III Wierix 1606). The ten quaternions are shown underneath the emperor flanked by the prince-electors (Archbishop of Trier, Archbishop of Cologne, Archbishop of Mainz; King of Bohemia, Count Palatine, Duke of Saxony, Margrave of Brandenburg).
A "Quaternion Eagle" (each quaternion being represented by four coats of arms on the imperial eagle's remiges) Hans Burgkmair, c. 1510. Twelve quaternions are shown, as follows (eight dukes being divided into two quaternions called "pillars" and "vicars", respectively[1]): Seill ("pillars"), Vicari ("vicars"), Marggrauen (margraves), Lantgrauen (landgraves), Burggrauen (burggraves), Grauen (counts), Semper freie (nobles), Ritter (knights), Stett (cities), Dörfer (villages), Bauern (peasants), Birg (castles).
The so-called imperial quaternions (German: Quaternionen der Reichsverfassung "quaternions of the imperial constitution"; from Latin quaterniō "group of four soldiers") were a conventional representation of the Imperial States of the Holy Roman Empire which first became current in the 15th century and was extremely popular during the 16th century.[2]
Apart from the highest tiers of the emperor, kings, prince-bishops and the prince electors, the estates are represented in groups of four. The number of quaternions was usually ten, in descending order of precedence Dukes (Duces), Margraves (Marchiones), Landgraves (Comites Provinciales), Burggraves (Comites Castrenses), Counts (Comites), Knights (Milites), Noblemen (Liberi), Cities (Metropoles), Villages (Villae) and Peasants (Rustici). The list could be shortened or expandend, by the mid-16th century to as many as 45.[3]
It is likely that this system was first introduced under Emperor Sigismund, who is assumed to have commissioned the frescoes in Frankfurt city hall in 1414.[4]
As has been noted from an early time, this representation of the "imperial constitution" does not in fact represent the actual constitution of the Holy Roman Empire, as some imperial cities appear as "villages" or even "peasants". E.g. the four "peasants" are Cologne, Constance, Regensburg and Salzburg. The Burggrave of Stromburg (or Straburg, Strandeck, and variants) was an unknown entity even at the time. The representation of imperial subjects is also far from complete. The "imperial quaternions" are, rather, a more or less random selection intended to represent pars pro toto the structure of the imperial constitution.
Typical representation of the quaternions (Anton III Wierix 1606). The ten quaternions are shown underneath the emperor flanked by the prince-electors (Archbishop of Trier, Archbishop of Cologne, Archbishop of Mainz; King of Bohemia, Count Palatine, Duke of Saxony, Margrave of Brandenburg).
THREE OR FOUR BARS ON THE TAIL
https://en.wikipedia.org/wiki/Philippine_hawk-cuckoo
It is a medium-sized cuckoo, about 29 centimetres in length. The adult is dark-grey above and white below with a pale rufous breast and upper belly. The tail has three or four black and buff bars, a broad black band near the tip and a pale rufous tip. There is a bare yellow ring around the eye. The legs and feet are also yellow and the bill is black and olive. Immature birds have rufous barring above and brown streaks below.
POSSIBLE FOURTH FOURTH ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Giant_peccary
The giant peccary (Pecari maximus) is a possible fourth species of peccary, discovered in Brazil in 2000 by Dutch naturalist Marc van Roosmalen. In 2003, he and German natural history filmmaker Lothar Frenz succeeded in filming a group and gathering material, which later would serve as the type. Though recently reported, it has been known to locals as caitetu munde, which means "great peccary which lives in pairs". It was formally described in 2007,[1] but the scientific evidence for its species status has later been questioned,[2][3] which also was one of the reasons for its initial evaluation as data deficient by IUCN in 2008. Following a review in 2011,[4] the IUCN moved the giant peccary into synonymy of the collared peccary (P. tajacu).[5]
four genera
https://en.wikipedia.org/wiki/Hemigaleidae#Paragaleus
The eight known species in this family are placed in four genera. Hemipristis is placed in the subfamily Hemipristinae, while Chaenogaleus, Hemigaleus, and Paragaleus are placed in the subfamily Hemigaleinae.[3]
FOUR LAYERS
The cortex thins from six layers to the three or four layers that make up the hippocampus. https://en.wikipedia.org/wiki/Hippocampus#Name In a cross-section of the hippocampus, including the dentate gyrus, several layers will be shown. The dentate gyrus has three layers of cells (or four if the hilus is included). The layers are from the outer in - the molecular layer, the inner molecular layer, the granular layer, and the hilus. The CA3 in the hippocampus proper has the following cell layers known as strata: lacunosum-moleculare, radiatum, lucidum, pyramidal, and oriens. CA2 and CA1 also have four each of these layers and not the lucidum stratum.
https://en.wikipedia.org/wiki/Stanislav_Grof
Stanislov Grof is a celebrated transpersonal psychologist who studied birth trauma. According to Grof there are four "hypothetical dynamic matrices in charge of the processes related to the perinatal level of the unconsciousness", called "basic perinatal matrices". These BPM's correspond to the stages of birth during the process of childbirth. Grof argued that during times of extraordinary distress, you undergo a kind of death in which these birth experiences are relived. They are
Square 1: BPM 1- the amniotic universe. This is the symbiotic unity between the Mother and the fetus.This state can be connected with experiences of a lack of boundaries and obstructions, such as the ocean and the cosmos. The extraordinary sentiment of the sacred and spiritual quality of BPM I is the experience of cosmic unity. The first square is the idealist, and the idealist is associated with spirituality and optimism.
Square 2: BPM 2-Cosmic Engulfment and No Exit. This matrix begins with the onset of labor. The experience of chemicals and the pressures of labor "interrupt the fetus’ blissful connection with the mother and alter its pristine universe." Experiencing this layer gives rise to a sense of "no escape", loneliness and helplessness is overwhelming.
Square 3: BPM 3- The Death-Rebirth Struggle.This matrix is associated with the move of the fetus through the birth channel. The third square is always the doing square. This matrix is concerned with a struggle for survival. When experiencing this layer, strong aggression and demonic forces are contacted. Memories associated with this matrix involve struggles, fights, and adventurous activities. The third square is always considered bad and violent.
Square 4: BPM 4-The Death-Rebirth Experience. The fourth square is associated with death. According to Grof, this matrix is connected to the stage of delivery, the actual birth of the child. Tension, pain and anxiety is released. The symbolic counterpart is the Death-Rebirth Experience. The transition from BPM III to BPM IV may involve a sense of total annihilation. Grof refers to this stage as an ego death. I discussed that the fourth square is the flow and knowledge. and is related to the death of the ego.
There are four articulations within the pelvis:
Sacroiliac Joints (x2) – Between the ilium of the hip bones, and the sacrum
Sacrococcygeal symphysis – Between the sacrum and the coccyx.
Pubic symphysis – Between the pubis bodies of the two hip bones.
FOURFOLD SCHEME OF PELVIS
https://en.wikipedia.org/wiki/Pelvis
Caldwell-Moloy classification[edit]
Throughout the 20th century pelvimetric measurements were made on pregnant women to determine whether a natural birth would be possible, a practice today limited to cases where a specific problem is suspected or following a caesarean delivery. William Edgar Caldwell and Howard Carmen Moloy studied collections of skeletal pelves and thousands of stereoscopic radiograms and finally recognized three types of female pelves plus the masculine type. In 1933 and 1934 they published their typology, including the Greek names since then frequently quoted in various handbooks: Gynaecoid (gyne, woman), anthropoid (anthropos, human being), platypelloid (platys, flat), and android (aner, man). [40][41]
The gynaecoid pelvis is the so-called normal female pelvis. Its inlet is either slightly oval, with a greater transverse diameter, or round. The interior walls are straight, the subpubic arch wide, the sacrum shows an average to backward inclination, and the greater sciatic notch is well rounded. Because this type is spacious and well proportioned there is little or no difficulty in the birth process. Caldwell and his co-workers found gynaecoid pelves in about 50 per cent of specimens.
The platypelloid pelvis has a transversally wide, flattened shape, is wide anteriorly, greater sciatic notches of male type, and has a short sacrum that curves inwards reducing the diameters of the lower pelvis. This is similar to the rachitic pelvis where the softened bones widen laterally because of the weight from the upper body resulting in a reduced anteroposterior diameter. Giving birth with this type of pelvis is associated with problems, such as transverse arrest. Less than 3 per cent of women have this pelvis type.
The android pelvis is a female pelvis with masculine features, including a wedge or heart shaped inlet caused by a prominent sacrum and a triangular anterior segment. The reduced pelvis outlet often causes problems during child birth. In 1939 Caldwell found this type in one third of white women and in one sixth of non-white women.
The anthropoid pelvis is characterized by an oval shape with a greater anteroposterior diameter. It has straight walls, a small subpubic arch, and large sacrosciatic notches. The sciatic spines are placed widely apart and the sacrum is usually straight resulting in deep non-obstructed pelvis. Caldwell found this type in one quarter of white women and almost half of non-white women.
http://www.innerbody.com/anatomy/skeletal/lower-torso/pelvis
The sacrum and coccyx also begin life as multiple bones before fusing. Five short, wide vertebrae fuse to form the wedge-shaped sacrum, while four tiny vertebrae fuse to form the coccyx.
The bones of the adult pelvis join together to form four joints: the left and right sacroiliac joints, the sacrococcygeal joint, and the pubic symphysis.
https://www.dartmouth.edu/~humananatomy/part_6/chapter_35.html
Each uterine tube is situated in the superior, free border and between the layers of the broad ligament. The uterine tube is subdivided into four parts, from lateral to medial: the infundibulum, ampulla, isthmus, and uterine part. The infundibulum, which is closely related to the ovary, contains the abdominal opening of the uterine tube, by which the tube is in communication with the peritoneal cavity. Oocytes pass from the ovary through the abdominal opening and along the uterine tube. The fimbriae are irregular fringes that project from the margin of the infundibulum, and one (ovarian fimbria) may be longer than the others. The ampulla, the longest and widest part, continues gradually into the isthmus. The uterine part, which lies in the wall of the uterus, contains the uterine opening of the uterine tube.
Figure 35-9 The blood supply to the female reproductive system. Extensive anastomoses occur between the ovarian and uterine arteries. Cervical branches of the uterine arteries anastomose across the median plane. The four-tiered concept of the reproductive system (A,B,C,D) is based on anatomical, physiological, and pathological data and may perhaps have embryological implications. For details see R. Contamin et al., Gynecol., 28:235-252, 1977.
https://en.wikipedia.org/wiki/Euarchontoglires
Euarchontoglires is now recognized as one of the four major subclades within the clade Eutheria (i.e., placentalia (placental mammals)[1]), and it is usually discussed without a taxonomic rank but has been regarded as a cohort, magnorder, or superorder. Relations among the four cohorts (Euarchontoglires, Xenarthra, Laurasiatheria, Afrotheria) and the identity of the placental root, remain controversial.[2]
FOUR TYPE OF CELLS PANCREAS
https://en.wikipedia.org/wiki/Pancreas
Approximately 3 million cell clusters called pancreatic islets are present in the pancreas.[10] Within these islets are FOUR types of cells which are involved in the regulation of blood glucose levels. Each type of cell secretes a different type of hormone: α alpha cells secrete glucagon (increase glucose in blood), β beta cells secrete insulin (decrease glucose in blood), δ delta cells secrete somatostatin (regulates/stops α and β cells) and PP cells, or γ (gamma) cells, secrete pancreatic polypeptide.[11] These act to control blood glucose through secreting glucagon to increase the levels of glucose, and insulin to decrease it.
FOUR HEART SOUNDS FOURTH IS DIFFERENT
S4[edit]
Main article: Fourth heart sound
S4 when audible in an adult is called a presystolic gallop or atrial gallop. This gallop is produced by the sound of blood being forced into a stiff or hypertrophic ventricle.
https://en.wikipedia.org/wiki/Heart_sounds
"ta-lub-dub" or "a-stiff-wall"
It is a sign of a pathologic state, usually a failing or hypertrophic left ventricle, as in systemic hypertension, severe valvular aortic stenosis, and hypertrophic cardiomyopathy. The sound occurs just after atrial contraction at the end of diastole and immediately before S1, producing a rhythm sometimes referred to as the "Tennessee" gallop where S4 represents the "Ten-" syllable.[2] It is best heard at the cardiac apex with the patient in the left lateral decubitus position and holding his breath. The combined presence of S3 and S4 is a quadruple gallop, also known as the "Hello-Goodbye" gallop. At rapid heart rates, S3 and S4 may merge to produce a summation gallop, sometimes referred to as S7.
Atrial contraction must be present for production of an S4. It is absent in atrial fibrillation and in other rhythms in which atrial contraction does not precede ventricular contraction.
THERE'S A DYNAMIC IN CHLOROPLASTS WHERE THEY ARE EITHER THREE OR FOUR MEMBRANED- THERE IS THE DYNAMIC BETWEEN THREE AND FOUR THE FOURTH IS DIFFERENT
Secondary endosymbiosis consisted of a eukaryotic alga being engulfed by another eukaryote, forming a chloroplast with three or four membranes.
https://en.wikipedia.org/wiki/Chloroplast
Green algae have been taken up by the euglenids, chlorarachniophytes, a lineage of dinoflagellates,[29] and possibly the ancestor of the chromalveolates[37] in three or four separate engulfments.[38] Many green algal derived chloroplasts contain pyrenoids, but unlike chloroplasts in their green algal ancestors, starch collects in granules outside the chloroplast.[14]
Chlorarachniophyte chloroplasts are bounded by four membranes, except near the cell membrane, where the chloroplast membranes fuse into a double membrane.[14] Their thylakoids are arranged in loose stacks of three.[14] Chlorarachniophytes have a form of starch called chrysolaminarin, which they store in the cytoplasm,[29] often collected around the chloroplast pyrenoid, which bulges into the cytoplasm.[14]
Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes.[16] Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.[14]
Apicoplasts have lost all photosynthetic function, and contain no photosynthetic pigments or true thylakoids. They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum.
Because the haptophyte chloroplast has four membranes, tertiary endosymbiosis would be expected to create a six membraned chloroplast, adding the haptophyte's cell membrane and the dinophyte's phagosomal vacuole
https://en.wikipedia.org/wiki/Filobasidiales
The Filobasidiales are an order in the fungal class Tremellomycetes. The one family in the order, the Filobasidiaceae, contains four species.[1] They are distinguished from other tremelloid species by the lack of a macroscopic basidiocarp.
FOUR MEMBERS OF THE FAMILY
https://en.wikipedia.org/wiki/Cation_channels_of_sperm
The cation channels of sperm also known as Catsper channels or CatSper, are ion channels that are related to the two-pore channels and distantly related to TRP channels. The four members of this family form voltage-gated Ca2+ channels that seem to be specific to sperm. As sperm encounter the more alkaline environment of the female reproductive tract, CatSper channels become activated by the altered ion concentration. These channels are required for proper fertilization.[1] The study of these channels has been slow because they do not traffic to the cell membrane in many heterologous systems.
Of the four members of the Catsper family, Catsper1 is found in the primary piece of sperm. Catsper1 plays an important role in evoked Ca2+ entry and regulation of hyperactivation in sperm. Catsper2 is localized in the sperm tail and is responsible for regulation of hyperactivation. Catsper3 and Catsper4 are found in both, the testes and sperm and play an important role in the motility of hyperactivated sperm. Although Catsper seems to play an important role in sperm function, Catspers1-4 null mice have been found to have normal testicular histology, sperm counts and morphology, which is indicative of normal progression of spermatogenesis. [2]
TETRADS
https://en.wikipedia.org/wiki/Micrococcus
Micrococcus (mi’ krō kŏk’ Əs) is a genus of bacteria in the Micrococcaceae family. Micrococcus occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from about 0.5 to 3 micrometers in diameter and typically appear in tetrads.
FOUR SUBUNITS
https://en.wikipedia.org/wiki/File:SuccDeh.svg
https://en.wikipedia.org/wiki/Succinate_dehydrogenase
Subunits[edit]
Mitochondrial and many bacterial monomer SQRs are composed of four subunits: two hydrophilic and two hydrophobic. The first two subunits, a flavoprotein (SdhA) and an iron-sulfur protein (SdhB), are hydrophilic. SdhA contains a covalently attached flavin adenine dinucleotide (FAD) cofactor and the succinate binding site and SdhB contains three iron-sulfur clusters: [2Fe-2S], [4Fe-4S], and [3Fe-4S]. The second two subunits are hydrophobic membrane anchor subunits, SdhC and SdhD. Human mitochondria contain two distinct isoforms of SdhA (Fp subunits type I and type II), these isoforms are also found in Ascaris suum and Caenorhabditis elegans.[2] The subunits form a membrane-bound cytochrome b complex with six transmembrane helices containing one heme b group and a ubiquinone-binding site, which can be seen in Image 4. Two phospholipid molecules, one cardiolipin and one phosphatidylethanolamine, are also found in the SdhC and SdhD subunits (not shown in the image). They serve to occupy the hydrophobic space below the heme b. These subunits are displayed in image 3. SdhA is green, SdhB is teal, SdhC is fuchsia, and SdhD is yellow. Around SdhC and SdhD is a phospholipid membrane with the intermembrane space at the top of the image.[3]
Table of subunit composition[4][edit]
No. Subunit name Human protein Protein description from UniProt Pfam family with Human protein
1 SdhA SDHA_HUMAN Succinate dehydrogenase [ubiquinone] flavoprotein subunit, mitochondrial Pfam PF00890, Pfam PF02910
2 SdhB SDHB_HUMAN Succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial Pfam PF13085, Pfam PF13183
3 SdhC C560_HUMAN Succinate dehydrogenase cytochrome b560 subunit, mitochondrial Pfam PF01127
4 SdhD DHSD_HUMAN Succinate dehydrogenase [ubiquinone] cytochrome b small subunit, mitochondrial Pfam PF05328
TAIL HAS THREE TO FOUR BARS
https://en.wikipedia.org/wiki/Ayres%27s_hawk-eagle
The adult male has blackish upperparts which are mottled with white, and usually has a white forehead and supercilium. The upper-wing coverts are similar. The tail is ashy grey with a broad black tip and three to four narrower dark bars. Primary
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THERE ARE 16 SPECIES OF PIG- SIXTEEN SQUARES QMR
http://animaldiversity.org/accounts/Suidae/
Sixteen species of pigs and hogs in eight genera make up the modern family Suidae. Suids originally occurred across Eurasia south of 48° N, on islands as far away as the Phillipines and Sulawesi, and throughout Africa. Humans have introduced Sus scrofa, from which the domesticated pigs are derived, in a variety of places around the world, including North America, New Zealand and New Guinea. Fossil suids are known from the Oligocene of Europe and Asia and the Miocene of Africa.
edit me. It's easy.
FOUR TUSKS
https://en.wikipedia.org/wiki/Metridiochoerus
Metridiochoerus is an extinct genus in the pig family indigenous to the Pliocene and Pleistocene of Africa. It is also known as the giant warthog.
Description[edit]
Restoration
Metridiochoerus was a large animal, 1.5 metres (4.9 ft) in length, resembling a giant warthog. It had two large pairs of tusks which were pointed sideways and curved upwards. Based on the complicated, knobbly pattern of the creature's molars, Metridiochoerus is considered to have been an omnivore.[1]
four species
https://en.wikipedia.org/wiki/Scymnodon
Scymnodon is a genus of squaliform sharks in the family Somniosidae.
Species[edit]
There are currently 4 recognized species in this genus: [1]
Scymnodon ichiharai Ka. Yano & S. Tanaka (II), 1984 (Japanese velvet dogfish) [1]
Scymnodon macracanthus Regan, 1906 (Largespine velvet dogfish) [1]
Scymnodon plunketi Waite, 1910 (Plunket's shark) [1]
Scymnodon ringens Barbosa du Bocage & Brito Capello, 1864 (Knifetooth dogfish)
There are four major types of neurons based on their shape. Unipolar neurons are the most common neurons in invertebrates. These neurons are characterized by one primary projection that serves as both the axon and the dendrites.
Another type of neurons is the bipolar neurons, each having an axon that transmits signals from the cell body going to the brain and the spinal cord, and dendrites that send signals from the body organs to the cell body. These bipolar neurons are usually found in sensory organs such as the eyes, nose and ears.
Pseudo-unipolar neurons resemble unipolar neurons because each of them has an axon, but no true dendrites. However, pseudo-unipolar neurons are actually variants of bipolar neurons. The reason for this is that the single axon attached to the cell body proceeds to two opposite “poles” or directions – one towards the muscle, joints and skin, and the other towards the spinal cord. Pseudo-unipolar neurons are responsible for the sense of touch, pain and pressure.
Multipolar neurons are the dominating neurons in vertebrates in terms of number. These neurons are the ones that are the closest to the model neuron that we usually see in neuron structure diagrams. Each of them has a cell body, a long axon, and short dendrites.
http://www.emory.edu/ANATOMY/AnatomyManual/pelvis.html
In the female, there are four columns of erectile tissue in the superficial pouch: two crura of the clitoris, which fuse anteriorly to form the clitoris; and the two bulbs of the vestibule.
Vaginal fornices:
https://www.mananatomy.com/body-systems/female-reproductive-system/vagina
At the upper end of the vagina, the anterior wall is pierced by the cervix which projects into it. The area of vaginal lumen, which surrounds the cervix, is divided into four fornices: anterior, posterior, right lateral and left lateral. These fornices are the deepest portions of the vagina, extending into the recesses created by the vaginal portion of the cervix.
http://www.uwyo.edu/wjm/repro/estrous.htm
All of this stuff is in my books
Stages. The estrous cycle can be divided into four stages: proestrus, estrus, metestrus, and diestrus. During proestrus the CL regresses (progesterone declines) and a preovulatory follicle undergoes its final growth phase (estradiol increases). Ovulation usually occurs during estrus (cows ovulate during metestrus). Proestrus and estrus comprise the follicular phase. Corpora lutea develop during metestrus and function at optimum during diestrus. Metestrus and diestrus make up the luteal phase.
https://en.wikipedia.org/wiki/Vagina
The wall of the vagina from the lumen outwards consists firstly of a mucosa of non-keratinized stratified squamous epithelium with an underlying lamina propria of connective tissue, secondly a layer of smooth muscle with bundles of circular fibers internal to longitudinal fibers, and thirdly an outer layer of connective tissue called the adventitia. Some texts list FOUR layers by counting the two sublayers of the mucosa (epithelium and lamina propria) separately.[22][23] The lamina propria is rich in blood vessels and lymphatic channels. The muscular layer is composed of smooth muscle fibers, with an outer layer of longitudinal muscle, an inner layer of circular muscle, and oblique muscle fibers between. The outer layer, the adventitia, is a thin dense layer of connective tissue, and it blends with loose connective tissue containing blood vessels, lymphatic vessels and nerve fibers that is present between the pelvic organs.[11][23][15]
Folds of mucosa (or vaginal rugae) are shown in the front third of a vagina
A normal cervix of an adult as seen through the vagina (per vaginam or PV) using a bivalved vaginal speculum. The blades of the speculum are above and below and stretched vaginal walls are seen on the left and right.
The mucosa forms folds or rugae, which are more prominent in the caudal third of the vagina; they appear as transverse ridges and their function is to provide the vagina with increased surface area for extension and stretching. Where the vaginal lumen surrounds the cervix of the uterus, it is divided into FOUR continuous regions or vaginal fornices; these are the anterior, posterior, right lateral, and left lateral fornices.[9][10] The posterior fornix is deeper than the anterior fornix.[10] While the anterior and posterior walls are placed together, the lateral walls, especially their middle area, are relatively more rigid; because of this, the vagina has a H-shaped cross section.[10] Behind, the upper one-fourth of the vagina is separated from the rectum by the recto-uterine pouch. Superficially, in front of the pubic bone, a cushion of fat called the mons pubis forms the uppermost part of the vulva.
https://en.wikipedia.org/wiki/Uterus
The uterus can be divided anatomically into four regions: The fundus, corpus (body), cervix and the internal os. The cervix protrudes into the vagina. The uterus is held in position within the pelvis by condensations of endopelvic fascia, which are called ligaments. These ligaments include the pubocervical, transverse cervical ligaments or cardinal ligaments, and the uterosacral ligaments. It is covered by a sheet-like fold of peritoneum, the broad ligament.[2]
https://en.wikipedia.org/wiki/Fallopian_tube
A cross section of Fallopian tube shows four distinct layers: serosa, subserosa, lamina propria and innermost mucosal layer
http://www.healthline.com/human-body-maps/male-urethra
The male urethra is comprised of four main segments. The preprostatic urethra runs in front of the prostate, while the prostatic urethra courses through that gland. The membranous urethra travels through the external urethral sphincter, while the spongy urethra travels the length of the penis and terminates at the meatus at the tip of the sexual organ.
http://spinningbabies.com/learn-more/birth-anatomy/
The bony pelvis has four joints. In the front of the pelvis is the symphysis pubis joint. Movement here really isn’t that comfortable. Sometimes a pregnancy belt holds this joint stable for walking and rolling over in bed. Symmetry in the symphysis pubis (pubic bone) reduces spasm in the round ligaments and helps the sacrum, around back, to be aligned properly.
On either side of the sacrum are the SI joints (Sacroilliac joints). These are located where the dimples are. Many plastic baby dolls have SI dimples above their bum. The SI joints are a common location for aches when the pelvis is weak or crooked.
Symmetry in the SI joints will help the sacrum be lined up with the pelvic brim. Then the baby can get into a nice, head down position. A chiropractic adjustment helps get the symphysis and the SI joints aligned.
The sacrum, rather than fused, is slightly mobile and in the birth process actually moves to allow the head past.
The tailbone is connected by a joint to the lower end of the sacrum. Sometimes this needs an adjustment, too, especially after birthing a baby. Ligaments connecting to the sacrum and tailbone (coccyx) will become more symmetrical and their tone will be more relaxed and less in spasm after bodywork on the pelvis.
Four pelvic types
Pelvic types
Four general pelvic types are taught in midwifery and obstetrical schools. Caldwell-Malloy (1933) taught that nearly half of Caucasian women have a Gynecoid pelvis (rounder at the inlet, but wider side-to-side and a little less room front-to-back) while nearly half of women of African descent are said to have an Anthropoid pelvis (oval at the inlet, roomiest front-to-back of all pelvic types).
About 1/4 of all women have an android pelvis, with it’s triangular inlet and a bit smaller outlet than its own inlet. Only about 5% of women are said to have a platypelloid pelvis.
Kuliukas (2015). looked at 64 women and did not find a clustering of four types but a range throughout.
Kuliukas, A., Kuliukas, L., Franklin, D., & Flavel, A. (2015). Female pelvic shape: Distinct types or nebulous cloud?. British Journal of Midwifery, 23(7).
Some research is suggestive of pelvic shape, especially width, having to do with physical activity habits in childhood.
Cardadeiro, G., Baptista, F., Janz, K. F., Rodrigues, L. A., & Sardinha, L. B. (2014). Pelvis width associated with bone mass distribution at the proximal femur in children 10–11 years old. Journal of bone and mineral metabolism, 32(2), 174-183.
The variety of pelvic shapes, combined with the variety of fetal head presentations, plus size variations, mean that labors vary greatly.
In the drawing above, we see pelvic inlet shape and the correlating shape of the pubic arch at the outlet.
Gynecoid
The Gynecoid pelvis has a roundish brim which allows fetal rotation when the muscles and ligaments in and around the pelvis aren’t tight and twangy.
gynecoid pelvis xray radiopaedia
The pelvic arch in front would allow three fingers to cover the urethra during a “potty dance” – the type of grab yourself and try not to pee your pants dance of a child waiting to get to the bathroom. Buttocks are round.
Hip size doesn’t indicate the roomy inside and a petite woman can birth a large baby. When the pelvic floor and other soft tissues aren’t overly tight, the birth tends to go well and a posterior baby can rotate at several various phases of labor.
Android
The android pubic arch may hang quite low, giving a fundal height reading higher than the compact bump may seem to justify. Closely-set, small buttock “muscles” of the android make small roundish or triangular cheeks to her “bottom.” The android pelvis definitely has a 2 finger arch, rather than the 3 finger of the gynecoid.
Posterior arrest is slightly highAnatomy drawings by Gail Gynecoid or Androider for women with an android pelvis. Good fetal positioning, good flexibility in the pelvic joints and balance in the soft tissues help the natural labor progress. The posterior baby will hope to rotate before engagement or may not be able to rotate until the head fully passes the pelvis rotating on the perineum. Some posterior babies, the larger ones or if a mom can’t get out of bed to do some rotation exercises, will need a cesarean, even with a skilled baby spinner present. Manually rotating the baby’s head may be an option if a skilled doctor or midwife is present. A little help for the shoulders may be needed as the result of those women with low slung pubic bones. They may catch a shoulder.
Tall women with average size babies often birth without an issue. I recommend flexible and balanced muscles before labor begins. Some women will need to start working out chronic pelvic torsion early in pregnancy or even before.
Recently a woman told me her doctor felt she may not be able to have a vaginal birth after she previously had a cesarean for birthing her first child. She asked me what I thought. While I acknowledge there are more challenges with an android pelvis for some of these labors, most births through an android pelvis are going to be able to finish by the woman’s own efforts -and her baby’s. I said:
I do know that women in your shoes…in your hips… do give birth every day. 24% of Caucasian women have android pelvis, and, almost that for women of African descent. And these womens’ great great grandmothers were birthing their great grandmothers, and their grandmothers were birthing their mothers, and one of them birthed you.
Anthropoid pelvisAnthropoid
Long pelvis front-to-back, perhaps a narrow arch, perhaps not. Buttocks muscles look longer up and down than the round buttocks of a gynecoid. The Anthropoid pelvic arch can vary.
The arch could be a narrow 2 fingers or a wider 3 fingers at the pubic arch (as shown here in the illustration). Measure the pubic arch about 1/3 of the way between the clitoris and the sitz bones, rather than the very top.
Common for breeches that don’t flip. More posterior babies who are born vaginally may be arriving through the anthropoid pelvis. Vertical maternal positions aid these fetal positions and help birth be more protected and finish by the mother’s own efforts.
Platypelloid
The pubic arch is a wide 4 finger span in the platypelloid, that is quite wide. A woman’s hips may seem slightly wider side-to-side than her weight would demand.
In other words, a thin woman with a platypelloid pelvis has wide hips but her pelvis from front and back is quite narrow. Her sitz bones are quite wide apart, more than the width of her fist (if she can reach between them while lying down).
Baby really needs to be in the LOT position to get INTO the pelvic brim for engagement. Long early labor is common, but if baby isn’t LOT, the two days of labor will be all about getting baby rotated and strong contractions and mobility are essential. Once baby is into the pelvis labor tends to move along, within 5-8 hours of engagement. Pushing may not be very long because the outlet of the pelvis is large. Using Daily Essentials: Activities for Pregnancy Comfort & Easier Childbirth, and Spinning Babies Parent Class may help your baby get into an LOT or other ideal position.
four pelvic cavities
The pelvic cavities of Gynecoid, Anthropoid, Android (narrowest at the bottom) and Platypelloid (widest at the bottom, narrow at the front to back at the top)
Which conclusions about how to fit pelvic shape into a label or category is less important to me than having a set of skills to identify what is going on between the baby and the mother at the inlet or other diameters of the pelvis and what we can do to help when help is indeed appropriate.
Here’s a story of how a woman who had a cesarean for her first baby who couldn’t engage in her pelvis went on to use The 3 Principles of Spinning Babies for her second birth:
Dear Gail: Just wanted you to know that the VBAC mom with the platypelloid pelvis had a successful unmedicated birth; surges were very intense with back labor for about 2 1/2 hours, mom was about 8cm dilated until the quality changed into a much more do-able intensity.
What helped was being on all fours, knee-chest position, strong hip squeezes, rebozo > standing did not work for a long time, just too intense, I think the walk to the car to transition to the hospital was helpful though – from there on it seemed so much easier. Active labor lasted just 3 hours, ½ hour pushing – the baby was sitting on the right side throughout the pregnancy, I think ROT; this mom was very dedicated, did chiropractic work (Webster technique) & craniosacral therapy – but the baby stayed on the right side; once we arrived in the hospital baby’s heartbeat was found on the left – I think the baby was born LOA; just saw this mom yesterday – she says hello to you – she worked with every bit of information.
https://en.wikipedia.org/wiki/Urethra
All of this is in my books
In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the external urethral meatus.{{[4]}} The urethra provides an exit for urine as well as semen during ejaculation.[1]
The urethra is divided into four parts in men, named after the location:
Region Description Epithelium
pre-prostatic urethra This is the intramural part of the urethra and varies between 0.5 and 1.5 cm in length depending on the fullness of the bladder. Transitional
prostatic urethra Crosses through the prostate gland. There are several openings: (1) the ejaculatory duct receives sperm from the vas deferens and ejaculate fluid from the seminal vesicle, (2) several prostatic ducts where fluid from the prostate enters and contributes to the ejaculate, (3) the prostatic utricle, which is merely an indentation. These openings are collectively called the verumontanum. Transitional
membranous urethra A small (1 or 2 cm) portion passing through the external urethral sphincter. This is the narrowest part of the urethra. It is located in the deep perineal pouch. The bulbourethral glands (Cowper's gland) are found posterior to this region but open in the spongy urethra. Pseudostratified columnar
spongy urethra (or penile urethra) Runs along the length of the penis on its ventral (underneath) surface. It is about 15–16 cm in length, and travels through the corpus spongiosum. The ducts from the urethral gland (gland of Littre) enter here. The openings of the bulbourethral glands are also found here.[5] Some textbooks will subdivide the spongy urethra into two parts, the bulbous and pendulous urethra. The urethral lumen runs effectively parallel to the penis, except at the narrowest point, the external urethral meatus, where it is vertical. This produces a spiral stream of urine and has the effect of cleaning the external urethral meatus. The lack of an equivalent mechanism in the female urethra partly explains why urinary tract infections occur so much more frequently in females. Pseudostratified columnar – proximally, Stratified squamous – distally
http://www.biology-pages.info/E/ExtraembryonicMembranes.html
Monotremes
These primitive mammals produce a shelled egg like their reptilian ancestors. Only four species exist today: three species of spiny anteater (echidna) and the duckbill platypus. [More]
http://www.biology-pages.info/E/ExtraembryonicMembranes.html
The embryos of reptiles, birds, and mammals produce 4 extraembryonic membranes, the
amnion
yolk sac
chorion, and
allantois
In birds and most reptiles, the embryo with its extraembryonic membranes develops within a shelled egg.
The amnion protects the embryo in a sac filled with amniotic fluid.
The yolk sac contains yolk — the sole source of food until hatching. Yolk is a mixture of proteins and lipoproteins.
The chorion lines the inner surface of the shell (which is permeable to gases) and participates in the exchange of O2 and CO2 between the embryo and the outside air.
The allantois stores metabolic wastes (chiefly uric acid) of the embryo and, as it grows larger, also participates in gas exchange.
With these four membranes, the developing embryo is able to carry on essential metabolism while sealed within the egg. Surrounded by amniotic fluid, the embryo is kept as moist as a fish embryo in a pond.
https://en.wikipedia.org/wiki/File:Glial_Cell_Types.png
https://en.wikipedia.org/wiki/Neuroglia
Illustration of the four different types of glial cells found in the central nervous system: ependymal cells (light pink), astrocytes (green), microglial cells (dark red), and oligodendrocytes (light blue).
Peters A (May 2004). "A fourth type of neuroglial cell in the adult central nervous system". Journal of Neurocytology. 33 (3): 345–57. doi:10.1023/B:NEUR.0000044195.64009.27. PMID 15475689.
https://en.wikipedia.org/wiki/Ependyma
Ependyma is one of the four types of neuroglia in the central nervous system (CNS). It is involved in the production of cerebrospinal fluid (CSF), and is shown to serve as a reservoir for neuroregeneration.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2760896/
Malaria is a parasitic infection caused by the 4 species of Plasmodium that infect humans: vivax, ovale, malariae, and falciparum. Of these, Plasmodium falciparum is the most deadly.
Pregnant women have an increased susceptibility to malaria infection. Malarial infection of the placenta by sequestration of the infected red blood cells leading to low birth weight and other effects. There are four types of malaria caused by the protozoan parasite Plasmodium falciparum (main), Plasmodium vivax, Plasmodium ovale, Plasmodium malariae). This condition is common in regions where malaria is endemic with women carrying their first pregnancy (primigravida).
https://en.wikipedia.org/wiki/Prostate
FOUR DISTINCT GLANDULAR REGIONS PROSTATE GLAND
The "zone" classification is more often used in pathology. The idea of "zones" was first proposed by John E. McNeal in 1968. McNeal found that the relatively homogeneous cut surface of an adult prostate in no way resembled "lobes" and thus led to the description of "zones".[12]
The prostate gland has four distinct glandular regions, two of which arise from different segments of the prostatic urethra:
Name Fraction of gland Description
Peripheral zone (PZ) Up to 70% in young men The sub-capsular portion of the posterior aspect of the prostate gland that surrounds the distal urethra. It is from this portion of the gland that ~70–80% of prostatic cancers originate.[13][14]
Central zone (CZ) Approximately 25% normally This zone surrounds the ejaculatory ducts. The central zone accounts for roughly 2.5% of prostate cancers although these cancers tend to be more aggressive and more likely to invade the seminal vesicles.[15]
Transition zone (TZ) 5% at puberty ~10–20% of prostate cancers originate in this zone. The transition zone surrounds the proximal urethra and is the region of the prostate gland that grows throughout life and is responsible for the disease of benign prostatic enlargement. (2)[13][14]
Anterior fibro-muscular zone (or stroma) Approximately 5% This zone is usually devoid of glandular components, and composed only, as its name suggests, of muscle and fibrous tissue.
The "lobe" classification is more often used in anatomy. There are four lobes
Anterior lobe (or isthmus) roughly corresponds to part of transitional zone
Posterior lobe roughly corresponds to peripheral zone
Lateral lobes spans all zones
Median lobe (or middle lobe) roughly corresponds to part of central zone
http://www.uky.edu/~brmacp/oralhist/module4/lab/imgshtml/image04.htm
Zones of the Pulp
The pulp cavity exhibits four zones as you progress from the dentin-pulp junction toward the center of the pulp cavity: 1) the odontoblast zone, 2) cell-free zone (basal layer of Weil), 3) cell-rich zone, and 4) the pulp core. A cell-free zone is not present in developing teeth but becomes prominent in the coronal pulp after development. The cell-rich zone lies immediately under the cell-free zone and contains numerous fibroblasts, macro-phages and capillaries. The capillaries arise from arterioles (C) deeper in the pulp but are commonly found adjacent to, or even within, the odontoblast layer. A large nerve bundle (B) is evident in this image forming part of the subondontoblastic plexus (of Raschkow). Nerve fibers pass from the plexus out toward the dentin. Occasionally a nerve fiber extends a short distance into the dentinal tubule with the odontoblast process. Pain is the only sensation carried from the pulp to the conscious level.
http://www.seiyaku.com/customs/crosses/pine-tree.html
Pine Tree Cross
Pine shootPine Tree Cross
Pine trees are grown for timber, wood pulp and also for use as Christmas Trees. But long before Christmas, by a curious quirk of nature, tiny crosses sprout from pine trees (in the northern hemisphere) just a couple of weeks before Easter.
How do these trees know it's Easter? Do they know that Christmas Trees are pagan, and display their little crosses at Easter to somehow compensate for that?
There are many different styles of cross; the ones on this photo are Bent Crosses, the style favoured by the pope. How on earth do these pine trees know all these things?
Well, they know because trees are remarkably clever. For example, they know that the taller they grow, the more sunlight they will get. At the same time, they know if they grow too tall, they won't be able to suck up sufficient moisture from the ground for survival.
They know that as soon as the male cones have shed their pollen, they are redundant and dumped onto the forest floor. They know that the female cones need to hang around a couple of years longer to mature after pollination.
Some varieties of pine know when to open their cones to release the seeds to the wind, and others attract birds to take and disperse the seeds. Yet other species hang on to their seeds for as many years as it takes before lightning strikes the forest and starts a fire. The heat opens the cones and the seeds fall to the burnt ground to start the life cycle all over again.
That's what trees do. They grow, and they generate seeds to perpetuate their species. It's called 'life' and the shoots that appear in spring, some of which happen to have a couple of perpendicular lateral shoots that make them look like crosses, are just part of that natural life cycle.
While Easter might be the same date in different parts of the world, spring isn't. So new shoot growth in north Africa appears several weeks before the same is seen in Norway. And in the southern hemisphere, Easter is in autumn.
Pine trees 'know' how to grow and there's plenty of evidence that pine trees are as intelligent as any other tree. However, there is no evidence to suggest that pine trees have any knowledge of human customs. Neither is there any mention in non-pagan sacred texts to suggest that trees have a soul.
Conversely, humans do have a soul but unfortunately we're not too sure how to grow. Fortunately, however, there are lessons in the sacred texts that can teach us.
Pine tree shoots do not appear as crosses by accident. They are there to remind us of the love shown by Jesus on the cross. See the meaning of the Cross.
https://www.thespruce.com/maltese-cross-plant-information-2…
But Does the Flower Really Look Like a Maltese Cross?
The Lychnis chalcedonica plants encountered most commonly in North America at present (apparently, this wasn't always the case) bear mainly flowers with five petals. But as any Maltese cross graphic will reveal, the Maltese cross symbol has four parts: namely, four "arrowheads" that intersect at their narrowest points. So if you, yourself own one of these plants sporting the five-petal look, you may start to wonder if the name "Maltese cross" is not perhaps a misnomer. The more you look at one of the five-petaled Maltese cross flowers, the more the discrepancy will bother you.
One can speculate that gardeners over the centuries have grown two versions of what we now know as "Maltese cross." Folks used to distinguish between the two. But, as time passed, the two came to be lumped together. One version, which has four petals, was first to claim the name "Maltese cross." The other, with five petals, may once have been called "Scarlet Lightning." So the latter now shares the name "Maltese cross" with the original perennials of that name, even though they are not, technically, cross-shaped (and to confuse matters further, the name "Scarlet Lighting" now doubles as an alternative common name for all Lychnis chalcedonica plants). Perhaps cross-breeding over the years reached a point where it was no longer deemed necessary to draw a distinction between the two.
The plant with the four-petaled flowers can best lay claim to the name "Maltese cross," because of the cross shape of its blooms. At least the five-petaled type does also display, at the tips of its petals, the signature indented Vs made famous by Maltese cross graphics.
There is still hope of witnessing a perfect Maltese cross even if you grow the five-petaled type. A stray four-petaled flower does crop up occasionally in a red sea of otherwise five-petaled blooms. When that happens, you will be as delighted as if you had just discovered a four-leaf clover.
FOUR PARTS OF TREE
https://simple.wikipedia.org/wiki/Tree
A tree is a tall plant with a trunk and branches made of wood. Trees can live for many years. The oldest tree ever discovered is approximately 5,000 years old. The four main parts of a tree are the roots, the trunk, the branches, and the leaves.
The divisions of the human spine are based on the quadrant model pattern. Biologists say that the human structure is based on random evolutionary processes. Humans may indeed be products of random evolution, but perceptions are not always to be trusted. An alternate interpretation is that humans have evolved to reveal the Quadrant Model of Reality—humans are made in the image and likeness of God. Existence may indeed express the quadrant model pattern through the form of the human. The quadrant model pattern is the expression of Being; it is the way existence manifests. God is Being.
The spine is divided as follows:
*Square one: the cervical
*Square two: the thoracic is the structure, and holds the ribs--the second square is always structure, order, and foundation
*Square three: lumbar. The third square is solid, physical, and associated with
movement; it is extremely robust and mobile.
*Square four: sacral. The fourth section of the spine is called the sacral, connoting a transcendent quality associated with the sacred or divine. It points to the fifth, which is associated with God. The qualities of the fourth always indicate the qualities of the fifth. The fifth is ultra transcendent, being very different from the other three parts of the spine. The discs in the sacrum are fused, whereas the discs in the previous three are not.
*Square five: cocygeal. known as the tailbone, and known as vestigial. Evolutionary biologists think that it is left over from the time when human ancestors had tails. The fourth never seems to belong, while the fifth always seems unneeded and is questionable. The fourth indicates the qualities of the fifth, both having fused discs.'
Most scientsists say there are four divisions leaving the cocygeal out
The human brain is arranged in accord with the quadrant model pattern. Earlier the suggestion was made that in the quadrant model pattern the first square is the light, the second is the word, the third is the flesh, the fourth is the true word and the fifth is true light. Another way to verbalize this is in the terminology used by Wilbur. He calls the first square “mind”, second “culture”, third “body”, and the fourth “social/society”. The fifth may be “God”.
The lobes of the brain are divided into four parts.
*Square one: occipital lobe--this is the light. The occipital lobe is responsible for vision, and corresponds to the Idealist square.
*Square two: temporal lobe- this is the word. The temporal lobe is responsible for hearing. Hearing or listening brings to mind culture. Listening is a social act that people do. This is the guardian square. Guardians are the most into friends and maintaining cultural harmony. Guardians are hearers. A fascinating thing about the temporal lobe is that this is where the fusiform facial area of the brain is. This area of the brain is responsible for distinguishing faces. Again, the second square is social. Recognizing face s is social. Guardians are very into social relationships. Also the temporal lobe is where the area of the brain associated with religiosity is located. The second square is the religious square. The second quadrant is belief, faith, behavior, and belonging. Religion maintains order and homeostasis. Guardians are very religious in their mentalities in that they often do not question things extremely deeply, but they are driven more by faith. The temporal lobe is where wernickes area of the brain is. This area is responsible for understanding language/hearing. This is the listening area of the brain. The temporal lobe is described as being the section of the brain associated with religiosity and relationships. This is the nature of the second square.
*Square three: parietal lobe--this is the flesh. The parietal lobe is associated with the sense of touch and movement. The parietal lobe is responsible for movement of the body. Recall that the third square is Wilber's body square. This is the artisan square. Artisans are the doers.
*Square four: frontal lobe--this is the true word--Wilbur's social/society square. It is associated with the personality type of the Rational. The fourth quadrant is contemplation and knowledge; the frontal lobe is where abstract reasoning occurs. The frontal lobe is also where brocas area is located. Brocas area is not responsible for hearing speech; it occurs in
the temporal lobe in the wernickes area. Brocas area is responsible for speaking. The fourth square is philosophy. The second square is religion. The philosopher speaks; the religious person listens and obeys. Both are needed and need each other. The qualities of each square are fulfilled.
https://en.wikipedia.org/wiki/Paranasal_sinuses
Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity.[1] The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the sphenoidal sinuses are behind the eyes. The sinuses are named for the facial bones in which they are located.
There are the four paranasal sinuses. They include
*Square one: maxillary sinus
*Square two: frontal sinus
*Square three: ethmoid sinus
*Square four: sphenoid sinus.
The first three sinuses are close to each other, but the fourth, the sphenoid sinus, is off by itself. This is the nature of the quadrant model--the fourth is always different from the previous three--a pattern expressed in the arrangement of the sinuses. Existence organizes itself along this pattern in areas that stand out to show that this pattern is significant and fundamental to reality.
Excerpt from my book Quadrant Model of Reality
Human taste receptors also fit the quadrant model pattern. They include
*Square one: bitter
*Square two: sweet
*Square three: sour
*Square four: salty (salt is NaCl)
*Square five: umami is Mono sodium glutamate. Sodium is Na. The fourth always points to the fifth. The fourth contains sodium, as does the fifth. Salty is different from the previous three, and the difference in fifth transcends all.
Bitter and sweet, the first two squares, form the duality. Sour is the third square, which always implies attributes of being bad and destructive.
https://en.wikipedia.org/wiki/Mechanoreceptor
A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous mammalian skin: lamellar corpuscles, tactile corpuscles, Merkel nerve endings, and bulbous corpuscles
https://en.wikipedia.org/wiki/Mechanoreceptor
There are four types of mechanoreceptors embedded in ligaments. As all these types of mechanoreceptors are myelinated, they can rapidly transmit sensory information regarding joint positions to the central nervous system.[10]
Type I: (small) Low threshold, slow adapting in both static and dynamic settings
Type II: (medium) Low threshold, rapidly adapting in dynamic settings
Type III: (large) High threshold, slowly adapting in dynamic settings
Type IV: (very small) High threshold pain receptors that communicate injury
https://www.ncbi.nlm.nih.gov/books/NBK10080/
Neurulation occurs in somewhat different ways in different regions of the body. The head, trunk, and tail each form their region of the neural tube in ways that reflect the inductive relationship of the pharyngeal endoderm, prechordal plate, and notochord to its overlying ectoderm (Chapters 10 and 11). The head and trunk regions both undergo variants of primary neurulation, and this process can be divided into four distinct but spatially and temporally overlapping stages: (1) formation of the neural plate; (2) shaping of the neural plate; (3) bending of the neural plate to form the neural groove; and (4) closure of the neural groove to form the neural tube (Smith and Schoenwolf 1997; see Figure 12.2).
FOUR ROWS OF HAIR CELLS RESPONSIBLE FOR HEARING- THE FOURTH ROW IS DIFFERENT
https://en.wikipedia.org/wiki/Cochlea
The hair cells are arranged in four rows in the organ of Corti along the entire length of the cochlear coil. Three rows consist of outer hair cells (OHCs) and one row consists of inner hair cells (IHCs). The inner hair cells provide the main neural output of the cochlea. The outer hair cells, instead, mainly receive neural input from the brain, which influences their motility as part of the cochlea's mechanical pre-amplifier. The input to the OHC is from the olivary body via the medial olivocochlear bundle.
FOUR TYPES OF TISSUE
https://en.wikipedia.org/wiki/Tissue_(biology)
Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.
Pines have four types of leaf:
https://en.wikipedia.org/wiki/Pine
Seed leaves (cotyledons) on seedlings, born in a whorl of 4–24.
Juvenile leaves, which follow immediately on seedlings and young plants, 2–6 cm long, single, green or often blue-green, and arranged spirally on the shoot. These are produced for six months to five years, rarely longer.
Scale leaves, similar to bud scales, small, brown and non-photosynthetic, and arranged spirally like the juvenile leaves.
Needles, the adult leaves, are green (photosynthetic) and bundled in clusters called fascicles. The needles can number from one to seven per fascicle, but generally number from two to five. Each fascicle is produced from a small bud on a dwarf shoot in the axil of a scale leaf. These bud scales often remain on the fascicle as a basal sheath. The needles persist for 1.5–40 years, depending on species. If a shoot is damaged (e.g. eaten by an animal), the needle fascicles just below the damage will generate a bud which can then replace the lost leaves.
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TETRADIC THEORY AND HUMAN KINSHIP
HE BELIEVES HUMANITY STARTED WITH A TETRADIC DRAVIDIAN SYSTEM- Tetra means four
https://www.jstor.org/stable/3134415?seq=1#page_scan_tab_contents
In Allen's world-historical theory of kinship, humanity began with a tetradic-Dravidian system based on cross-cousin marriage and defined by alternate generation, prescriptive, and classificatory equations
https://en.wikipedia.org/wiki/Ramachandran_plot
FOURTH SQUARE OF PLOT IS EMPTY- FOURTH ALWAYS DIFFERENT
A Ramachandran plot (also known as a Ramachandran diagram or a [φ,ψ] plot), originally developed in 1963 by G. N. Ramachandran, C. Ramakrishnan, and V. Sasisekharan,[1] is a way to visualize backbone dihedral angles ψ against φ of amino acid residues in protein structure and identify sterically allowed regions for these angles. The figure at left illustrates the definition of the φ and ψ backbone dihedral angles[2] (called φ and φ' by Ramachandran). The ω angle at the peptide bond is normally 180°, since the partial-double-bond character keeps the peptide planar.[3] The figure at top right shows the allowed φ,ψ backbone conformational regions from the Ramachandran et al. 1963 and 1968 hard-sphere calculations: full radius in solid outline, reduced radius in dashed, and relaxed tau (N-Calpha-C) angle in dotted lines.[4] Because dihedral angle values are circular and 0° is the same as 360°, the edges of the Ramachandran plot "wrap" right-to-left and bottom-to-top. For instance, the small strip of allowed values along the lower-left edge of the plot are a continuation of the large, extended-chain region at upper left.
The plot is in the form of a quadrant.
A Ramachandran plot can be used in two somewhat different ways. One is to show in theory which values, or conformations, of the ψ and φ angles are possible for an amino-acid residue in a protein (as at top right). A second is to show the empirical distribution of datapoints observed in a single structure (as at right, here) in usage for structure validation, or else in a database of many structures (as in the lower 3 plots at left). Either case is usually shown against outlines for the theoretically favored regions.
The fourth square of a Rakmachandran plot is empty. The fourth square is always different.
https://en.wikipedia.org/wiki/Helix-turn-helix
The winged helix-turn-helix (wHTH) motif is formed by a 3-helical bundle and a 3- or 4-strand beta-sheet (wing). The topology of helices and strands in the wHTH motifs may vary. In the transcription factor ETS wHTH folds into a helix-turn-helix motif on a four-stranded anti-parallel beta-sheet scaffold arranged in the order α1-β1-β2-α2-α3-β3-β4 where the third helix is the DNA recognition helix.[13][14]
THE FOURTH IS ALWAYS DIFFERENT- THREE BASE IS WHAT PEOPLE ONLY THOUGHT THERE WERE- BUT THERE IS FOUR
http://www.cell.com/abstract/0092-8674(81)90067-2
Four-base codons ACCA, ACCU and ACCC are recognized by frameshift suppressor sufJ
Lionello Bossi∗, John R. Roth
Department of Biology University of Utah Salt Lake City, Utah 84112, USA
∗Present address: Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah 84112.
DOI: http://dx.doi.org/10.1016/0092-8674(81)90067-2
Summary
References
Comments
Abstract
The frameshift suppressor sufJ acts to correct a set of +1 frameshift mutations having very different sequences at their mutant sites. This suppressor acts by reading a 4 base codon located near, but not at, the site of each suppressible mutation. Suppression thus necessitates out-of-phase translation of the short stretch of mRNA between the site of action of the suppressor tRNA and the site of the frameshift mutation. We have identified the site read by sufJ by mutationally creating a series of such sites in the neighborhood of a previously nonsuppressible frameshift mutation. Each of the newly generated sites was formed by base substitution. Four independently generated sites were analyzed by DNA sequencing. At each site the quadruplet codon ACCX was generated (where X is A, U or C). Thus sufJ is able to read a 4 base codon in which any of three bases is acceptable in the fourth position. This is the first frameshift suppressor that does not read a run of three repeated bases in the first three positions of its codon.
https://www.truthorfiction.com/laminin/
Laminin, an Important Protein that Looks Like a Cross-Truth!
Summary of eRumor:
The eRumor talks of a substance called “laminin” that is described as part of a family of proteins that “hold us together.” Then there is a picture of laminin—which looks like a cross.
The Truth:
This story leads into complex considerations of science and biology but the main questions it prompts are whether laminin is as important as the eRumor claims and does it have a shape like a cross.
The simple answer to both questions seems to be yes.
Laminin is defined by the Webster Medical Dictionary as a “glycoprotein that is a component of connective tissue basement membrane and that promotes cell adhesion.” In other words, looking at laminin as a kind of glue isn’t far from the truth. There are several different laminins.
In their book The Laminins authors Peter Elkblom and Rupert Timpl go into more detail about both the importance of laminins and their structure. They describe laminins that, together with other proteins, “hold cells and tissues together.” They also say, “Electron microscopy reveals a cross-like shape for all laminins investigated so far.” They went on to say that in solution the laminin shapes were more like a flower than a cross. The strands of laminins do not always stand straight and at right angles, but they do consists of arms, three of which are short and one of which is long.
Research has been conducted on laminins in connection with numerous conditions and diseases. It has been found, for example, that people with congenital muscular dystrophies do not have laminin-alpha2, which is normally found in the layer of cells around muscle fibers and other cells important to the structural integrity of muscle cells.
Updated 5/14/08
FOUR HORNS
The ferocious vegetarian: Two ton, 20ft long 'alien horned-face' dinosaur discovered in Canada
Scientists re-examining old fossils found in Canada have named a massive new species of dinosaur which wielded four horns and weighed as much as two tons.
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Follow us: @MailOnline on Twitter | DailyMail on Facebook
Scientists re-examining old fossils found in Canada have named a massive new species of dinosaur which wielded four horns and weighed as much as two tons.
Follow us: @MailOnline on Twitter | DailyMail on Facebook
Fearsome: Xenoceratops foremostensis, which was up to 20ft long and weighed two tons, has been identified from fossils collected in the Fifties in Canada
Fearsome: Xenoceratops foremostensis, which was up to 20ft long and weighed two tons, has been identified from fossils collected in the Fifties in Canada
Four families of river dolphins (Iniidae, Pontoporiidae, Lipotidae and Platanistidae) are currently recognized
https://en.wikipedia.org/wiki/River_dolphin
https://en.wikipedia.org/wiki/File:River_dolphins.jpg
River dolphins are not a taxon, they are an informal grouping of the infraorder Cetacea
River dolphins.jpg
Four species
https://en.wikipedia.org/wiki/Eastern_long-beaked_echidna
There are four recognized subspecies of Zaglossus bartoni :[4]
Z. bartoni bartoni
Z. bartoni clunius
Z. bartoni smeenki
Z. bartoni diamondi
https://en.wikipedia.org/wiki/Sirenia
Four species of sirenians exist.
https://en.wikipedia.org/wiki/Manatee
Manatees comprise three of the four living species in the order Sirenia. The fourth is the Eastern Hemisphere's dugong. The Sirenia are thought to have evolved from four-legged land mammals over 60 million years ago, with the closest living relatives being the Proboscidea (elephants) and Hyracoidea (hyraxes).[4]
https://en.wikipedia.org/wiki/Eusporangiate_fern
There are four extant eusporangiate fern families.
FOUR GENERA
https://en.wikipedia.org/wiki/Ophioglossaceae
In all modern classifications, from the Smith system of 2006 forward, Ophioglossaceae is the single family in order Ophioglossales.[4][5][6] The Smith system of 2006 divides the family into four genera: Botrychium s.l. (including Sceptridium, Botrypus, and Japanobotrychium), Helminthostachys, Mankyua, and Ophioglossum s.l. (including Cheiroglossa and Ophioderma).[4] Christenhusz et al., in 2011, recognized Cheiroglossa as a segregate of Ophioglossum.[5] The Christenhusz and Chase system of 2014 included Cheiroglossa in Ophioglossum again.[7] The PPG I system divides the family into four subfamilies:[6]
Helminthostachyoideae, containing Helminthostachys
Mankyuoideae, containing Mankyua
Ophioglossoideae, containing Cheiroglossa, Ophioderma, Ophioglossum, and Rhizoglossum (equivalent to Ophioglossum s.l. in other systems)
Botrychioideae, containing Botrychium, the non-monophyletic genus Botrypus, Japanobotrychium, and Sceptridium (similar to the circumscription of Kato;[8] equivalent to Botrychium s.l. in other systems)
https://en.wikipedia.org/wiki/Schistosoma
The mansoni group[edit]
The four mansoni group species are: S. edwardiense, S. hippotami, S. mansoni and S. rodhaini.
FOUR SUBGENERA
https://en.wikipedia.org/wiki/Meriones_(rodent)
The 17 species of Meriones jirds are divided into four subgenera.
Genus Meriones
Subgenus Meriones
Tamarisk jird, Meriones tamariscinus
Subgenus Parameriones
Persian jird, Meriones persicus
King jird, Meriones rex
Subgenus Pallasiomys
Arabian jird, Meriones arimalius
Cheng's jird, Meriones chengi
Sundevall's jird, Meriones crassus
Dahl's jird, Meriones dahli
Moroccan jird, Meriones grandis
Libyan jird, Meriones libycus
Midday jird, Meriones meridianus
Buxton's jird, Meriones sacramenti
Shaw's jird, Meriones shawi
Tristram's jird, Meriones tristrami
Mongolian gerbil or Mongolian jird, Meriones unguiculatus
Vinogradov's jird, Meriones vinogradovi
Zarudny's jird, Meriones zarudnyi
Subgenus Cheliones
Indian desert jird, Meriones hurrianae
https://en.wikipedia.org/wiki/Welsh_Pony_and_Cob
The Welsh Pony and Cob are a group of four closely related horse breeds including both pony and cob types, which originated in Wales in the United Kingdom. The four sections within the breed society for the Welsh breeds are primarily distinguished by height, but also by variations in type: the Welsh Mountain Pony (Section A), the Welsh Pony (Section B), the Welsh Pony of Cob Type (Section C), and the Welsh Cob (Section D). Welsh ponies and cobs are known for their good temperament, hardiness, and free-moving gaits.
https://en.wikipedia.org/wiki/Four-eyed_fish
The four-eyed fishes are a genus, Anableps, of fishes in the family Anablepidae. They have eyes raised above the top of the head and divided in two different parts, so that they can see below and above the water surface at the same time.
Like their relatives, the onesided livebearers, four-eyed fishes only mate on one side, right-"handed" males with left-"handed" females and vice versa.
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Four 'humanoid' figures from Linnaeus’s 'Academic delights'
Four 'humanoid' figures: (L-R) Troglodyta Bontu, Lucifer Aldrovandi, Satyrus Tulpii and Pygmaeus Edwardi from thesis CV 'Anthropomorpha' by Christianus Emmanuel Hoppius, 1760, published in volume 6 of Amoenitates academicae (Stockholm, 1763).
https://pictures.royalsociety.org/assets/object_images/4/04/2404/v0_web.jpg
https://pictures.royalsociety.org/image-rs-9160
Amoenitates academicae ('Academic delights', 10 volumes, 1749-1790) was published in Carl Linnaeus's name, and edited by him (vols 1-7) and J C D Schreber (vols 8-10). It consisted of theses presented and defended by students at Uppsala University.
FOUR CLASSES
https://en.wikipedia.org/wiki/Tetrapod
The classification of tetrapods has a long history. Traditionally, tetrapods are divided into four classes based on gross anatomical and physiological traits.[
FOUR TYPES OF JUNCTION
Important for the barrier function of intenstinal epithelium, its cells are joined securely together by four types of junctions (cell junctions),[11] which can be identified at the ultrastructural level:[12]
https://en.wikipedia.org/wiki/Intestinal_epithelium
Gap junctions
Desmosomes
Adherens junctions
Tight junctions
Gap junctions[edit]
Gap junctions bring the adjacent cells within 2 nanometers of each other. They are formed by several homologous proteins encoded by the connexin gene family coming together to form a multiprotein complex. The molecular structure of this complex is in the form of a hexamer. The complex, which is embedded in the cell walls of the two joined cells, forms a gap or channel in the middle of the six proteins. This channel allows various molecules, ions and electrical impulses to pass between the two cells.[13]
Desmosomes[edit]
These complexes, consisting of transmembrane adhesion proteins of the cadherin family, link adjacent cells together through their cytoskeletons.[14] Desmosomes leave a gap of 30 nanometers between cells.[13]
Adherens junctions[edit]
Adherens junctions, also called zonula adherens, are multiprotein complexes formed by proteins of the catenin and cadherin families. They are located in the membrane at the contact points between the cells. They are formed by interactions between intracellular adapter proteins, transmembrane proteins and the actin cytoskeletons of the cells . Besides their role in linking adjacent cells, these complexes are important for regulating epithelial migration, cell polarity, and the formation of other cell junction complexes.[12]
Tight junctions[edit]
Tight junctions, also called zonula occludens, are the most important components of the intenstinal epithelium for its barrier function.[15] These complexes, formed primarily of members of the claudin and the occludin families, consist of about 35 different proteins,[11] form a ring shaped continuous ribbon around the cells, and are located near the borders of the lateral and apical membranes.[12]
The extracellular domains of the transmembrane proteins in adjacent cells cross connect to form a tight seal. These interactions include those between proteins in the same membrane ("cis") and proteins in adjacent cells ("trans"). In addition, interactions can be homophilic (between identical proteins) or heterophilic (between different proteins).[12]
Similar to adherens junctions, the intracellular domains of tight junctions interact with different scaffold proteins, adapter proteins and signaling complexes to regulate cytoskeletal linking, cell polarity, cell signaling and vesical trafficking.[12]
Tight junctions provide a narrow but modifiable seal between adjacent cells in the epithelial layer and thereby provide selective paracellular transport of solutes.[12] While previously thought to be static structures, tight junctions are now known to be dynamic and can change the size of the opening between cells and thereby adapt to the different states of development, physiologies and pathologies.[15] They function as a selective and semipermeable paracellular barrier between apical and basolateral compartments of the epithelial layer. They function to facilitate the passage of small ions and water-soluble solutes through the paracellular space while preventing the passage of luminal antigens, microorganisms and their toxins.[12]
FOUR GROUPS
https://en.wikipedia.org/wiki/Evolutionary_history_of_plants
The more familiar leaves, megaphylls, are thought to have separate origins – indeed, they appeared four times independently, in the ferns, horsetails, progymnosperms, and seed plants.[55] They appear to have originated from dichotomising branches, which first overlapped (or "overtopped") one another, and eventually developed "webbing" and evolved into gradually more leaf-like structures.[53] So megaphylls, by this "teleome theory", are composed of a group of webbed branches[53] – hence the "leaf gap" left where the leaf's vascular bundle leaves that of the main branch resembles two axes splitting.[53] In each of the four groups to evolve megaphylls, their leaves first evolved during the Late Devonian to Early Carboniferous, diversifying rapidly until the designs settled down in the mid Carboniferous.[55]
https://en.wikipedia.org/wiki/Tetragonula_carbonaria
Tetragonula carbonaria (previously known as Trigona carbonaria) is a stingless bee, endemic to the north-east coast of Australia.[2] Its common name is sugarbag bee.
FOUR SUBSPECIES
https://en.wikipedia.org/wiki/Western_honey_bee
The subspecies are divided into four major branches, based on work by Ruttner and confirmed by mitochondrial DNA analysis. African subspecies belong to branch A, northwestern European subspecies branch M, southwestern European subspecies branch C and Middle-Eastern subspecies branch O.
FOUR STEPS
https://en.wikipedia.org/wiki/History_of_biochemistry
Polymerase chain reaction[edit]
Shown above is a model of a thermo cycler that is currently being used in polymerase chain reaction.
Polymerase chain reaction (PCR) is the primary gene amplification technique that has revolutionized modern biochemistry. Polymerase chain reaction was developed by Kary Mullis in 1983.[33] There are four steps to a proper polymerase chain reaction: 1) denaturation 2) extension 3) insertion (of gene to be expressed) and finally 4) amplification of the inserted gene
https://en.wikipedia.org/wiki/Internal_carotid_artery
Terminologia Anatomica in 1998 subdivided the artery into four parts: "cervical", "petrous", "cavernous", and "cerebral".
https://en.wikipedia.org/wiki/Gut_flora
The four dominant bacterial phyla in the human gut are Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria
FOUR SPOTS
https://en.wikipedia.org/wiki/West_Coast_lady
Most conspicuously, it lacks obvious ventral eyespots on the hindwings; there are two large ones on V. virginiensis and four small ones on V. cardui
TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetrapodomorpha
The Tetrapodomorpha (also known as Choanata[1]) are a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish. Advanced forms transitional between fish and the early labyrinthodonts, such as Tiktaalik, have been referred to as "fishapods" by their discoverers, being half-fish, half-tetrapods, in appearance and limb morphology. The Tetrapodomorpha contains the crown group tetrapods (the last common ancestor of living tetrapods and all of its descendants) and several groups of early stem tetrapods, which includes several groups of related lobe-finned fishes, collectively known as the osteolepiforms. The Tetrapodamorpha minus the crown group Tetrapoda are the Stem Tetrapoda, a paraphyletic unit encompassing the fish to tetrapod transition.
https://en.wikipedia.org/wiki/Hyena
A more recent molecular analysis gives a slightly different phylogenetic relationship between the four extant hyaenidae species (Koepfli et al, 2006[18]).
Hyaenidae
Proteles cristatus (aardwolf) The life of animals (Colored Plate 4) (proteles cristatus).jpg
Crocuta crocuta (spotted hyena) Hyaena maculata - 1818-1842 - Print - Iconographia Zoologica - Special Collections University of Amsterdam -(white background).jpg
Parahyaena brunnea (brown hyena) Hyaena fusca (white background).jpg
Hyaena hyaena (striped hyena) Hyaena striata - 1818-1842 - Print - Iconographia Zoologica - Special Collections University of Amsterdam -(white background).jpg
https://en.wikipedia.org/wiki/Hyena
FOUR SPECIES
Hyenas or hyaenas (from Greek ὕαινα hýaina[1]) are any feliform carnivoran mammals of the family Hyaenidae /haɪˈɛnᵻdiː/. With only four extant species, it is the fifth-smallest biological family in the Carnivora, and one of the smallest in the class Mammalia.[2] Despite their low diversity, hyenas are unique and vital components of most African ecosystems
The lumbar arteries are arteries located in the lower back or lumbar region. The lumbar arteries are in parallel with the intercostals.
https://en.wikipedia.org/wiki/Lumbar_arteries
They are usually FOUR in number on either side, and arise from the back of the aorta, opposite the bodies of the upper four lumbar vertebrae.
TETRAMER- FOUR REGIONS OF MONOMERS
https://en.wikipedia.org/wiki/Lac_repressor
Structurally, the lac repressor protein is a homo-tetramer. The tetramer contains two DNA binding subunits composed of two monomers each (sometimes called "dimeric lac repressor"). These subunits dimerize to form a tetramer capable of binding two operator sequences. Each monomer [3][4][5] consists of four distinct regions:
an N-terminal DNA-binding domain (in which two LacI proteins bind a single operator site)
a regulatory domain (sometimes called the core domain, which binds allolactose, an allosteric effector molecule)
a linker that connects the DNA-binding domain with the core domain (sometimes called the hinge helix, which is important for allosteric communication[5])
a C-terminal tetramerization region (which joins four monomers in an alpha-helix bundle)
DNA binding occurs via an N-terminal helix-turn-helix structural motif and is targeted to one of several operator DNA sequences (known as O1, O2 and O3). The O1 operator sequence slightly overlaps with the promoter, which increases the affinity of RNA polymerase for the promoter sequence such that it cannot enter elongation and remains in Abortive initiation. Additionally, because each tetramer contains two DNA-binding subunits, binding of multiple operator sequences by a single tetramer induces DNA looping.[6]
FOUR WHITE STRIPES ON FACE
https://en.wikipedia.org/wiki/Tent-making_bat
The tent-making bat (Uroderma bilobatum) is an American leaf-nosed bat (Phyllostomidae) found in lowland forests of Central and South America. This medium-sized bat has a gray coat with a pale white stripe running down the middle of the back. Its face is characterized by a fleshy noseleaf and four white stripes
https://en.wikipedia.org/wiki/Striped_hyena
The flanks have four indistinct dark vertical stripes and rows of diffused spots. The outer surface of the thighs has 3–4 distinct vertical or oblique dark bands which merge into transverse stripes in the lower portion of the legs. The tip of the tail is black with white underfur.[14]
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https://en.wikipedia.org/wiki/Echidna
Echidnas /ᵻˈkɪdnə/, sometimes known as spiny anteaters,[1] belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. The four extant species
https://en.wikipedia.org/wiki/Fox_sparrow
https://en.wikipedia.org/wiki/File:FoxSparrowMap.png
The review by Zink & Weckstein (2003),[3] which added mtDNA cytochrome b, NADH dehydrogenase subunit 2 and 3, and D-loop sequence, confirmed the four "subspecies groups"[4] of the fox sparrow that were outlined by the initial limited mtDNA haplotype comparison (Zink 1994).[5] These should probably be recognized as separate species, but this was deferred for further analysis of hybridization. Particularly the contact zones between the slate-colored and thick-billed fox sparrows which are only weakly distinct morphologically were of interest; the other groups were found to be distinct far earlier.[6] A further study of the nuclear genome, using microsatellites, showed similar separation between the four groups.[7]
https://en.wikipedia.org/wiki/Yellow-eyed_junco
Similar to the situation in the dark-eyed junco, this species's systematics is still in need of much research before they can be considered resolved. Four subspecies groups are usually distinguished. These are, north to south:
Mexican junco, Junco phaeonotus phaeonotus.[2]
High mountains of Mexico, southeastern Arizona and southwestern New Mexico.
Baird's junco, Junco phaeonotus bairdi.[3]
High mountains of Baja California Sur
Chiapas junco, Junco phaeonotus fulvescens.[4]
High mountains of Chiapas, southeast Mexico.
Guatemala junco, Junco phaeonotus alticola.[5]
High mountains of eastern Chiapas (southeast Mexico) and Guatemala.
https://en.wikipedia.org/wiki/Lion_tamarin
The four species of lion tamarins make up the genus Leontopithecus. They are small New World monkeys named for the mane surrounding their face similar to the mane of a lion.
FOUR
https://en.wikipedia.org/wiki/Lion_tamarin
The different species of lion tamarins are easily discernible from each other, based upon the coloration of their fur:[1]
Golden lion tamarin, L. rosalia — golden fur all over, mane sometimes darkening or black
Golden-headed lion tamarin, L. chrysomelas — black fur with golden face, arms, and tail
Black lion tamarin or golden-rumped lion tamarin, L. chrysopygus — black fur with a dark gold rump
Superagui lion tamarin or black-faced lion tamarin, L. caissara — golden fur with black face, arms, and tails
https://en.wikipedia.org/wiki/Golden_lion_tamarin
Native to the Atlantic coastal forests of Brazil, the golden lion tamarin is an endangered species with an estimated wild population of about 3,500[4] individuals spread between four places along southeastern Brazil
FOUR SPECIES
https://en.wikipedia.org/wiki/Lynx
A lynx (/ˈlɪŋks/;[2] plural lynx or lynxes[3]) is any of the four species within the Lynx genus of medium-sized wild cats, which includes the bobcat. The name "lynx" originated in Middle English via Latin from the Greek word λύγξ,[2] derived from the Indo-European root leuk- ("light, brightness")[4] in reference to the luminescence of its reflective eyes.[4]
The four living species of the Lynx genus are believed to have evolved from the "Issoire lynx", which lived in Europe and Africa during the late Pliocene to early Pleistocene. The Pliocene felid Felis rexroadensis from North America has been proposed as an even earlier ancestor; however, this was larger than any living species, and is not currently classified as a true lynx.[12]
Eurasian lynx
Eurasian lynx
Main article: Eurasian lynx
Of the four lynx species, the Eurasian lynx (Lynx lynx) is the largest in size. It is native to European, Central Asian, and Siberian forests. While its conservation status has been classified as "least concern", populations of Eurasian lynx have been reduced or extirpated from Europe, where it is now being reintroduced.
The bobcat resembles other species of the Lynx genus, but is on average the smallest of the four. Its coat is variable, though generally tan to grayish brown, with black streaks on the body and dark bars on the forelegs and tail. The ears are black-tipped and pointed, with short, black tufts. There is generally an off-white color on the lips, chin, and underparts. Bobcats in the desert regions of the southwest have the lightest-colored coats, while those in the northern, forested regions have the darkest.[11]
Behavior and diet
The lynx is usually solitary, although a small group of lynx may travel and hunt together occasionally. Mating takes place in the late winter and once a year the female gives birth to between one and four kittens. The gestation time of the lynx is about 70 days. The young stay with the mother for one more winter, a total of around nine months, before moving out to live on their own as young adults. The lynx creates its den in crevices or under ledges. It feeds on a wide range of animals from white-tailed deer, reindeer, roe deer, small red deer, and chamois, to smaller, more usual prey: snowshoe hares, fish, foxes, sheep, squirrels, mice, turkeys and other birds, and goats. It also eats ptarmigans, voles, and grouse.
https://en.wikipedia.org/wiki/Felidae
Sabretooth "cats" seem to belong to four different lineages.
https://en.wikipedia.org/wiki/Mamba
Mambas are fast-moving venomous snakes of the genus Dendroaspis (which literally means "tree asp") in the family Elapidae. Four extant species are recognised currently; three of those four species are essentially arboreal and green in colour, whereas the so-called black mamba, Dendroaspis polylepis, is largely terrestrial and generally brown or grey in colour. All are native to various regions in sub-Saharan Africa and all are feared throughout their ranges, especially the black mamba. In Africa there are many legends and stories about mambas.[2][3][4]
Contents [hide]
1 Behaviour
2 Venom
2.1 Mamba toxins
3 Species
4 References
5 External links
Behaviour[edit]
The three species of green mambas are arboreal, whereas the black mamba is largely terrestrial. All four species are active diurnal hunters, preying on birds, lizards, and small mammals. At nightfall some species, especially the terrestrial black mamba, shelter in a lair. A mamba may retain the same lair for years.
https://en.wikipedia.org/wiki/Shark_attack
The great white shark is the first of only four species of sharks that have been involved in a significant number of fatal unprovoked attacks on humans
FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Oryx
Oryx is a genus consisting of four large antelope species. Three of them are native to arid parts of Africa, and the fourth to the Arabian Peninsula. Their fur is pale with contrasting dark markings in the face and on the legs, and their long horns are almost straight. The exception is the scimitar oryx, which lacks dark markings on the legs, only has faint dark markings on the head, has an ochre neck, and horns that are clearly decurved.
FOUR SPECIES
https://en.wikipedia.org/wiki/Ichthyostega
https://en.wikipedia.org/wiki/Tiktaalik
In 1932 Gunnar Säve-Söderbergh described four Ichthyostega species from the Upper Devonian of East Greenland and one species belonging to the genus Ichthyostegopsis, I. wimani. These species could be synonymous (in which case only I. stensioei would remain), because their morphological differences are not very pronounced. The species differ in skull proportions, skull punctuation and skull bone patterns. The comparisons were done on 14 specimens collected in 1931 by the Danish East Greenland Expedition. Additional specimens were collected between 1933 and 1955.
QMR
NATURAL FOUR BEAT GAIT
https://en.wikipedia.org/wiki/Paso_Fino
The Paso Fino is a naturally gaited light horse breed dating back to horses imported to the Caribbean from Spain. Pasos are prized for their smooth, natural, four-beat, lateral ambling gait; they are used in many disciplines, but are especially popular for trail riding. In the United States two main groups of horses are popularly called "Paso Fino:" One, also known as the Pure Puerto Rican Paso Fino (PPR), originated in Puerto Rico.[1] The other, often called the Colombian Paso Fino or Colombian Criollo Horse (CCC), developed in Colombia. Though from similar Spanish ancestors, the two groups developed independently of one another in their home nations.
TETRA MEANS FOUR
https://en.wikipedia.org/wiki/Dwarf_crocodile
The dwarf crocodile (Osteolaemus tetraspis), also known commonly as the African dwarf crocodile, broad-snouted crocodile, or bony crocodile, is an African crocodile that is also the smallest extant crocodile species. Recent sampling has identified three genetically distinct populations. Some feel that the findings should elevate the subspecies to full species status.
The specific epithet, tetraspis, means "four shields", and derives from the Ancient Greek τετρα (four) and ασπίς (shield), as the back of the neck has four large, shield-like scales.
FOUR LIFE STAGES
https://en.wikipedia.org/wiki/Western_honey_bee
Like other insects that undergo complete metamorphosis, the western honey bee has four distinct life stages: egg, larva, pupa and adult.
https://en.wikipedia.org/wiki/Extensor_digitorum_muscle
The extensor digitorum muscle (also known as extensor digitorum communis) is a muscle of the posterior forearm present in humans and other animals. It extends the medial four digits of the hand.
It arises from the lateral epicondyle of the humerus, by the common tendon; from the intermuscular septa between it and the adjacent muscles, and from the antebrachial fascia. It divides below into four tendons, which pass, together with that of the extensor indicis proprius, through a separate compartment of the dorsal carpal ligament, within a mucous sheath. The tendons then diverge on the back of the hand, and are inserted into the middle and distal phalanges of the fingers in the following manner. [2]
https://en.wikipedia.org/wiki/Carbohydrate
The term is most common in biochemistry, where it is a synonym of 'saccharide', a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides
Mammals express four arrestin subtypes and each arrestin subtype is known by multiple aliases. The systematic arrestin name (1-4) plus the most widely used aliases for each arrestin subtype are listed in bold below:
https://en.wikipedia.org/wiki/Arrestin
Arrestin-1 was originally identified as the S-antigen (SAG) causing uveitis (autoimmune eye disease), then independently described as a 48 kDa protein that binds light-activated phosphorylated rhodopsin before it became clear that both are one and the same. It was later renamed visual arrestin, but when another cone-specific visual subtype was cloned the term rod arrestin was coined. This also turned out to be a misnomer: arrestin-1 expresses at comparable very high levels in both rod and cone photoreceptor cells.
Arrestin-2 was the first non-visual arrestin cloned. It was first named β-arrestin simply because between two GPCRs available in purified form at the time, rhodopsin and β2-adrenergic receptor, it showed preference for the latter.
Arrestin-3. The second non-visual arrestin cloned was first termed β-arrestin-2 (retroactively changing the name of β-arrestin into β-arrestin-1), even though by that time it was clear that non-visual arrestins interact with hundreds of different GPCRs, not just with β2-adrenergic receptor. Systematic names, arrestin-2 and arrestin-3, respectively, were proposed soon after that.
Arrestin-4 was cloned by two groups and termed cone arrestin, after photoreceptor type that expresses it, and X-arrestin, after the chromosome where its gene resides. In the HUGO database its gene is called arrestin-3.
FOUR EYESPOTS
https://en.wikipedia.org/wiki/Australian_painted_lady
The Australian painted lady is remarkably similar to the painted lady (Vanessa cardui). It is differentiated by its smaller size, rarely exceeding 2 inches (5 cm) across its wings, and the blue colouration at the centre of the four eyespots on its hindwings. Its body is dark brown, almost black, all over, except the tips of the antenna which are white. The base of the wings are brown, which turns into a brick red colouration, broken by bands of black. The tips of the forewing are black with four white dots running from the apex of the wing, and a white bar extending from the leading edge of the forewing. The hindwings have four round eyespots at their base, with a blue centre for at least three. The underwings are almost identical to the upperwings, except the base of the underwings is brick red rather than brown. The Australian painted lady's colouration allows it to blend in effectively with the ground.[8] Males and females look almost identical.[9] The ovum is translucent green in colour and barrel shaped with 13 to 15 vertical ribs. Right before hatching, the black head and grey-tinted body appear through the shell.[10] The larva is grey with pale yellow stripes along each side of its body,[11] yellow dots,[8] and has rows of branched spines covering its body.[9] Its head is typically brown or black, and the caterpillar grows to about 3 cm. The pupa is brown with darker markings, and four pairs of metallic silver or gold dots.[9]
Taxonomy[edit]
The Australian painted lady belongs to the family Nymphalidae and genus Vanessa, which compromises 22 species, which are strongly migratory.[12] The Australian painted lady is similar to the near-cosmopolitan painted lady (V. cardui), so it considered by some to be a subspecies of that. However, throughout its range, the painted lady does not exhibit much variation, but the male genitalia of the Australian painted lady is distinct from that of the painted lady, which suggests that it is a separate species.[3] The Australian species' four ventral eyespots are less clearly defined, and it always sports at least three (often four) conspicuous blue pupil spots on each dorsal hindwings' eyespots. V. cardui has either a few tiny pupil spots, or more often, none at all.[4]
https://en.wikipedia.org/wiki/Pancreatic_branches_of_splenic_artery
There are four main pancreatic branches of the splenic artery:[1]
Greater pancreatic artery
Dorsal pancreatic artery
Inferior pancreatic artery (aka transverse pancreatic artery)
Caudal pancreatic artery
FOUR EYES- TETRA MEANS FOUR
https://en.wikipedia.org/wiki/Tetrablemma
The spider genus Tetrablemma is unusual in possessing only four eyes, a trait only found elsewhere in most species of the family Caponiidae. The two are not closely related.
FOUR STAGE LIFECYCLE- USED IN HUMAN CANCER RESEARCH BECAUSE OF ITS UNIQUE FOUR STAGE LIFE CYCLE
https://en.wikipedia.org/wiki/Dictyostelium_discoideum
Dictyostelium discoideum is a species of soil-living amoeba belonging to the phylum Amoebozoa, infraphylum Mycetozoa. Commonly referred to as slime mold, D. discoideum is a eukaryote that transitions from a collection of unicellular amoebae into a multicellular slug and then into a fruiting body within its lifetime. Its unique asexual lifecycle consists of four stages: vegetative, aggregation, migration, and culmination. The lifecycle of D. discoideum is relatively short, which allows for timely viewing of all stages. The cells involved in the lifecycle undergo movement, chemical signaling, and development, which are applicable to human cancer research. The simplicity of its lifecycle makes D. discoideum a valuable model organism to study genetic, cellular, and biochemical processes in other organisms.
https://en.wikipedia.org/wiki/Four-lined_snake
Elaphe quatuorlineata (common names: four-lined snake, Bulgarian ratsnake[3]) is a member of the family Colubridae.[4] The four-lined snake is a non-venomous species and one of the largest in the Colubridae.[5]
https://en.wikipedia.org/wiki/Edward_Topsell
Topsell's The History of Four-footed Beasts (1607) and The History of Serpents (1608), both published by William Jaggard, were reprinted together as The History of Four-Footed Beasts and Serpents in 1658. An 1100-page treatise on zoology, Topsell's work repeats ancient and fantastic legends about actual animals, as well as reports of mythical animals. Topsell, not a naturalist himself, relied on earlier authorities, most notably the Historiae animalium of the Swiss scholar Conrad Gessner. "I would not have the Reader," Topsell writes, "... imagine I have ... related all that is ever said of these Beasts, but only [what] is said by many."[3]
The sable antelope (Hippotragus niger) is an antelope which inhabits wooded savannah in East Africa south of Kenya, and in Southern Africa.
https://en.wikipedia.org/wiki/Sable_antelope
Hipotrachus niger has four subspecies:
H. n. niger, the southern sable or black sable (also known as the Matsetsi, south-Zambian and common sable) is regarded as the 'typical' sable, as it was the first to be described and named in 1838. Often referred to as the black sable because it tends to have the darkest coat, this subspecies occurs south of the Zambezi River, particularly in northern Botswana and in large numbers in the Matsetsi valley of Zimbabwe, but is also found in South Africa. In South Africa, most of the commercial sable farmers crossed their Matsetsi sables (indigenous to South Africa) with western Zambian sables in the hope to move nearer to the nearly extinct giant sable (that was larger with bigger horns.) Currently, only about 15% pure Matsetsi sables are thought to exist in South Africa. The Matsetsi sable population in Zimbabwe is only 450 (down from 24,000 in 1994). The sable population in South Africa is about 7,000 (commercial and in reserves). Therefore, the Matsetsi sable population apparently is less than 1,500 and declining. Fortunately, most of the sables in the reserves are pure Matsetsi sables. Anglo-American recently started a program of breeding pure Matsetsi sables commercially and keeping them pure.[4][5]
H. n. variani, the giant sable antelope or royal sable, is so named because the horns of both sexes are recognizably longer. It is found only in a few remaining localities in central Angola. It is classified as Critically Endangered on the IUCN Red List, and is listed on Appendix I of CITES.
H. n. kirkii, the Zambian sable or west-Tanzanian sable, but also known as "west-Zambian sable", occurs in central Angola, western Zambia and Malawi, and has the largest geographical range, which extends north of the Zambezi River through Zambia, eastern DRC and Malawi into south-western Tanzania. It is classified as vulnerable [6][7]
H. n. roosevelti, the eastern sable or Shimba sable, is the smallest of the subspecies. It occurs in the coastal hinterlands of southern Kenya, particularly in the Shimba Hills National Reserve, and ranges through the region east of Tanzania's eastern escarpment and into northern Mozambique.[7][8]
FOUR SPECIES KANGAROO
https://en.wikipedia.org/wiki/Kangaroo
There are four species that are commonly referred to as kangaroos:
The red kangaroo (Macropus rufus) is the largest surviving marsupial anywhere in the world. It occupies the arid and semi-arid centre of the country. The highest population densities of the red kangaroo occur in the rangelands of western New South Wales. Red kangaroos are commonly mistaken as the most abundant species of kangaroo, but eastern greys actually have a larger population.[18] A large male can be 2 metres (6 ft 7 in) tall and weigh 90 kg (200 lb).[19]
The eastern grey kangaroo (Macropus giganteus) is less well-known than the red (outside Australia), but the most often seen, as its range covers the fertile eastern part of the country. The range of the eastern grey kangaroo extends from the top of the Cape York Peninsula in north Queensland down to Victoria, as well as areas of south-eastern Australia and Tasmania. Population densities of eastern grey kangaroos usually peak near 100 per km2 in suitable habitats of open woodlands. Populations are more limited in areas of land clearance, such as farmland, where forest and woodland habitats are limited in size or abundance.[18]
The western grey kangaroo (Macropus fuliginosus) is slightly smaller again at about 54 kg (119 lb) for a large male. It is found in the southern part of Western Australia, South Australia near the coast, and the Darling River basin. The highest population densities occur in the western Riverina district of New South Wales and in western areas of the Nullarbor Plain in Western Australia. Populations may have declined, particularly in agricultural areas. The species has a high tolerance to the plant toxin sodium fluoroacetate, which indicates a possible origin from the south-west region of Australia.[18]
The antilopine kangaroo (Macropus antilopinus) is, essentially, the far-northern equivalent of the eastern and western grey kangaroos. It is sometimes referred to as the antilopine wallaroo, but in behaviour and habitat it is more similar to red and grey kangaroos. Like them, it is a creature of the grassy plains and woodlands, and gregarious. Its name comes from its fur, which is similar in colour and texture to that of antelopes. Characteristically, the noses of males swell behind the nostrils. This enlarges nasal passages and allows them to release more heat in hot and humid climates.[18]
https://en.wikipedia.org/wiki/Rhagodia_(arachnid)
Rhagodia is a genus in the arachnid order Solifugae, comprising four species. R. abessinica is found in Ethiopia, while the other three species are found in the Near East, from Turkey to Pakistan.[1]
FOUR SEROGROUPS
https://en.wikipedia.org/wiki/Shigella
Shigella is one of the leading bacterial causes of diarrhea worldwide, causing an estimated 80-165 million cases.[6] The number of deaths it causes each year is estimated at between 74,000 and 600,000 deaths.[6][7] It is in the top four pathogens that cause moderate-to-severe diarrhea in African and South Asian children.[8]
Contents [hide]
1 Classification
2 Pathogenesis
3 Diagnosis
4 Prevention and treatment
5 See also
6 References
7 External links
Classification[edit]
Shigella species are classified by four serogroups:
Serogroup A: S. dysenteriae (15 serotypes)[9]
Serogroup B: S. flexneri (six serotypes)
Serogroup C: S. boydii (19 serotypes)[10]
Serogroup D: S. sonnei (one serotype)
https://en.wikipedia.org/wiki/Protist
The formal taxonomic category Protoctista was first proposed in the early 1860s by John Hogg, who argued that the protists should include what he saw as primitive unicellular forms of both plants and animals. He defined the Protoctista as a "fourth kingdom of nature", in addition to the then-traditional kingdoms of plants, animals and minerals
https://en.wikipedia.org/wiki/Protist
In contrast, Copeland's term included nucleated eukaryotes such as diatoms, green algae and fungi.[19] This classification was the basis for Whittaker's later definition of Fungi, Animalia, Plantae and Protista as the four kingdoms of life
four species sand tiger shark
https://en.wikipedia.org/wiki/Sand_tiger_shark
Because the sand tiger shark is worldwide in distribution, it has many common names. The term "sand tiger shark" actually refers to four different sand tiger shark species in the family Odontaspididae. Furthermore, the name creates confusion with the tiger shark Galeocerdo cuvier, which is not related to the sand tiger. The grey nurse shark, the name used in Australia and the United Kingdom, is the second-most-used name for the shark, and in India it is known as blue-nurse sand tiger. However, there are unrelated nurse sharks in the family Ginglymostomatidae. The most unambiguous and descriptive English name is probably the South African one, spotted ragged-tooth shark.[2][4]
Identification[edit]
There are four species of sand tiger sharks[2]
The sand tiger shark Carcharias taurus
The Indian sand tiger shark Carcharias tricuspidatus. Very little is known about this species which, described before 1900, is probably the same as (a synonym of) the sand tiger C. taurus[2]
The small-toothed sand tiger shark Odontaspis ferox. This species has a worldwide distribution, is seldom seen but normally inhabits deeper water than does C. taurus.
The large-eyed sand tiger shark Odontaspis noronhai, a deep water shark of the Americas, of which little is known.
Diagram indicating the differences between C. taurus and O. ferox
The most likely problem when identifying the sand tiger shark is when in the presence of either of the two species of Odontaspis. Firstly, the sand tiger is usually spotted, especially on the hind half of the body. However, there are several other differences that are probably more reliable:
The bottom part of the caudal fin (tail fin) of the sand tiger is smaller;
The second (i.e. hind) dorsal fin of the sand tiger is almost as large as the first (i.e. front) dorsal fin.
The first (i.e. front) dorsal fin of the sand tiger is relatively non-symmetric;
The first (i.e. front) dorsal fin of the sand tiger is closer to the pelvic fin than to the pectoral fin (i.e. the first dorsal fin is positioned further backwards in the case of the sand tiger);
CAUSE THE COLD
https://en.wikipedia.org/wiki/Alphacoronavirus
Alphacoronaviruses are the first of the four genera, alpha-, beta-, gamma-, and delta-coronavirus in the subfamily Coronavirinae of the family Coronaviridae
CAUSE COMMON COLD FAMILY
https://en.wikipedia.org/wiki/Betacoronavirus
Betacoronaviruses are one of four genera of coronaviruses of the subfamily Coronavirinae in the family Coronaviridae, of the order Nidovirales. They are enveloped, positive-sense, single-stranded RNA viruses of zoonotic origin. The coronavirus genera are each composed of varying viral lineages with the betacoronavirus genus containing four such lineages.
Within the genus Betacoronavirus (Group 2 CoV), four lineages (a, b, c, and d) are commonly recognized.
Lineage A includes HCoV-OC43 and HCoV-HKU1 (various species)
Lineage B includes SARS-CoV (various species):
Lineage C includes Tylonycteris bat coronavirus HKU4 (BtCoV-HKU4), Pipistrellus bat coronavirus HKU5 (BtCoV-HKU5), and MERS-CoV (various species)
Lineage D includes Rousettus bat coronavirus HKU9 (BtCoV-HKU9)[7]
FOUR SPECIES EFFECT HUMANS
https://en.wikipedia.org/wiki/Brucellosis
Brucella species are small, gram-negative, nonmotile, nonspore-forming, rod-shaped (coccobacilli) bacteria. They function as facultative intracellular parasites, causing chronic disease, which usually persists for life. Four species infect humans: B. abortus, B. canis, B. melitensis, and B. suis. B. abortus is less virulent than B. melitensis and is primarily a disease of cattle. B. canis affects dogs. B. melitensis is the most virulent and invasive species; it usually infects goats and occasionally sheep. B. suis is of intermediate virulence and chiefly infects pigs. Symptoms include profuse sweating and joint and muscle pain. Brucellosis has been recognized in animals and humans since the 20th century.
https://microbewiki.kenyon.edu/index.php/Plasmodium
There are four types of Plasmodium which cause human malaria: Plasmodium falciparum, Plasmodium ovale, Plasmodium vivax, and Plasmodium malariae.
While the four major species of Plasmodium differ in some ways from each other, they all share the same complex life cycle involving the insect (mosquito) vector and the human host
https://microbewiki.kenyon.edu/index.php/Plasmodium
The other produced a fever every third day and was called quartan. In 1890, Giovanni Batista Grassi and Raimondo Filetti, Italian investigators, introduced the names Plasmodium vivax and P. malariae ‘ for the two of the four malaria parasites which are now known to affect humans. In 1897, American William H. Welch revisited Laveran’s work and named a third malaria parasite P. falciparum. Finally in 1922, John W. W. Stephens found a fourth malaria parasite affecting humans, P. ovale. Ronald Ross, a British officer, discovered in 1897 that humans are able to pass the malaria parasite into mosquitoes by releasing malaria-free mosquitoes into the rooms of malaria patients. The actual life or sporogonic cycle of the parasites was first described in 1899 by Giovanni Batista Grassi (4).
The four species of Plasmodium that affect humans are different morphologically, slightly in terms of their life cycles, in terms of their host erythrocite preferences, and varying clinical symptoms.
https://en.wikipedia.org/wiki/Plestiodon_tetragrammus
The four-lined skink (Plestiodon tetragrammus)[2] is a species of lizard, which is endemic to North America. It is a medium-sized member of the Plestiodon skinks.
One lizard, four species: the collared treerunner
21 January 2014 / Chris
https://news.mongabay.com/2014/01/one-lizard-four-species-the-collared-treerunner/
Now, that’s a horse of a different color. Or, in this case, a lizard of another species–four species. Recent research suggests that the collared treerunner (Plica plica), previously thought of as one widespread species, is actually four distinct species inhabiting diverse geographical areas east of the Andes in northern South America.
One lizard, four species: the collared treerunner
Collared treerunner in Colombia
Collared treerunner in Colombia. Photo by Rhett A. Butler
Now, that’s a horse of a different color. Or, in this case, a lizard of another species—four species.
Recent research suggests that the collared treerunner (Plica plica), previously thought of as one widespread species, is actually four distinct species inhabiting diverse geographical areas east of the Andes in northern South America.
“The four new species described here all appear to be associated with areas of endemism or specific features of the northern South American landscape,” write John Murphy of Chicago’s Field Museum of Natural History and Michael Jowers of the Estación Biológica de Doñana in Spain in their article published in ZooKeys.
Elanus is a genus of bird of prey in the elanid kite subfamily. It consists of four species.
https://en.wikipedia.org/wiki/Elanus
Black-winged kite, Elanus caeruleus
Black-shouldered kite, Elanus axillaris
White-tailed kite, Elanus leucurus
Letter-winged kite, Elanus scriptus
The first three species above were considered conspecific as subspecies of Elanus caeruleus, which has been known as the black-shouldered kite.
These are white and grey raptors of open country, with black wing markings and a short square tail. They hunt by slowly quartering the habitat for rodents and other small mammals, birds and insects, sometimes hovering like a kestrel.
https://en.wikipedia.org/wiki/Milvus
FOUR SPECIES
Genus Milvus
Red kite, Milvus milvus
Cape Verde kite, Milvus (milvus) fasciicauda – extinct (2000)
Black kite, Milvus migrans
Black-eared kite, Milvus (migrans) lineatus
Yellow-billed kite, Milvus (migrans) aegyptius
This is an Old World group consisting of three kites that form part of the subfamily Milvinae. Its systematics are under revision; it contains 3 or 4 species.
Red kite, Milvus milvus
Cape Verde kite, Milvus (milvus) fasciicauda extinct (2000)
Black kite, Milvus migrans
Black-eared kite, Milvus (migrans) lineatus
Yellow-billed kite, Milvus aegyptius
FOUR GENERA
https://en.wikipedia.org/wiki/Elephant_shrew
The 19 species of elephant shrew are placed in four genera, one of which is monotypic:
ORDER MACROSCELIDEA[1]
Family Macroscelididae
Genus Elephantulus
Short-snouted elephant shrew, E. brachyrhynchus
Cape elephant shrew, E. edwardii
Dusky-footed elephant shrew, E. fuscipes
Dusky elephant shrew, E. fuscus
Bushveld elephant shrew, E. intufi
Eastern rock elephant shrew, E. myurus
Karoo rock elephant shrew, E. pilicaudus[14]
Somali elephant shrew, E. revoili
North African elephant shrew, E. rozeti
Rufous elephant shrew, E. rufescens
Western rock elephant shrew, E. rupestris
Genus Macroscelides
Namib round-eared sengi, M. flavicaudatus
Etendaka round-eared sengi, M. micus
Round-eared elephant shrew, M. proboscideus
Genus Petrodromus
Four-toed elephant shrew, P. tetradactylus
Genus Rhynchocyon
Golden-rumped elephant shrew, R. chrysopygus
Checkered elephant shrew, R. cirnei
Black and rufous elephant shrew, R. petersi
Grey-faced sengiR. udzungwensis [15]
https://en.wikipedia.org/wiki/Rhynchocyon
FOUR SPECIES
Rhynchocyon is a genus of elephant shrew (or sengi) in the family Macroscelididae.[1] Members of this genus are known colloquially as the checkered elephant shrews[2] or giant sengis.[3] It contains the following four species:
Golden-rumped elephant shrew, Rhynchocyon chrysopygus
Checkered elephant shrew, Rhynchocyon cirnei
Black and rufous elephant shrew, Rhynchocyon petersi
Grey-faced sengi, Rhynchocyon udzungwensis [4]
https://en.wikipedia.org/wiki/Bird_of_prey
The taxonomy of Carl Linnaeus grouped birds (class Aves) into orders, genera, and species, with no formal ranks between genus and order. He placed all birds of prey into a single order, Accipitres, subdividing this into four genera: Vultur (vultures), Falco (eagles, hawks, falcons, etc.), Strix (owls), and Lanius (shrikes). This approach was followed by subsequent authors such as Gmelin, Latham, and Turnton.
https://en.wikipedia.org/wiki/Origin_of_birds
Witmer in 2009 concluded that this evidence is sufficient to demonstrate that avian evolution went through a four-winged stage.[
FOUR WINGED BIRDS BOOK FOUR PARTS
https://en.wikipedia.org/wiki/The_Origin_of_Birds
Heilmann's book was divided into four main parts. The first three draw evidence for bird evolution from the fossil record, from the embryos of birds and other animals, and from living birds, respectively. The fourth and most groundbreaking section examines several groups of extinct animals in order to determine the probable root of modern birds.[1]
Beebe's leg-wings[edit]
Heilmann's illustrations, redrawn from Beebe's work, showing the hindlimbs of various nestlings and one reptile
In the fourth section of The Origin of Birds, Heilmann examines the Tetrapteryx hypothesis proposed by William Beebe in 1915. This hypothesis was based on observations of bird embryos and hatchlings, which Beebe found to possess a presumably atavistic fringe of flight feathers on their hindlimbs. His main evidence came from examination of incipient quill feathers on the thigh of a four-day-old white-winged dove. He theorized based on this embryological fringe and the recapitulation theory that birds had once passed through a "Tetrapteryx" stage in their distant evolution, which he represented as a hypothetical four-winged gliding animal.[50]
Beebe was relatively undeterred by the scientific community's acceptance of Heilmann's rejection of his theory, as is evidenced by the fact that he was still writing about his Tetrapteryx hypothesis well into the 1940s.[53] His adherence to his theory was well-placed, as in 2003 a revolutionary discovery was made in the early Cretaceous Jiufotang Formation of Liaoning, China: Microraptor gui, the small, four-winged dromaeosaur that had led to renewed credence of the arboreal model for the origin of bird flight. This animal's most remarkable feature was the existence of long, pennaceous feathers on both its arms and legs, forming a set of four aerodynamic wings that its discoverers theorized were used for gliding.[54] This discovery had the immediate effect of resurrecting the idea that leg feathers may have had some bearing on the origin of flight in birds, building on the idea originally proposed by Beebe and rejected by Heilmann.[55]
Today, Beebe's 1915 description of his hypothetical four-winged bird ancestor is regarded as prescient, and there is no doubt that Microraptor looks startlingly similar to the almost-century old Tetrapteryx illustrations.[56] After its discovery, Microraptor had the effect of both reinvigorating the arboreal hypothesis as well as finally putting an end to the widespread acceptance of Heilmann's disregard for the Tetrapteryx theory.[57]
FOUR GENERA OF CRANE
https://en.wikipedia.org/wiki/Crane_(bird)
Taxonomy and systematics[edit]
Grey crowned crane in captivity at Martin Mere, UK
Red-crowned cranes (genus Grus).
There are 15 living species of cranes in four genera:
SUBFAMILY BALEARICINAE – crowned cranes
Genus Balearica
Black crowned crane, Balearica pavonina
Grey crowned crane, Balearica regulorum
SUBFAMILY GRUINAE – typical cranes
Genus Grus
Common crane, Grus grus, also known as the Eurasian crane
Sandhill crane, Grus canadensis
Whooping crane, Grus americana
Sarus crane, Grus antigone
Brolga, Grus rubicunda
Siberian crane, Grus leucogeranus
White-naped crane, Grus vipio
Hooded crane, Grus monacha
Black-necked crane, Grus nigricollis
Red-crowned crane, Grus japonensis, also known as the Manchurian crane and Japanese crane
Genus Anthropoides
Blue crane, Anthropoides paradisea
Demoiselle crane, Anthropoides virgo
Genus Bugeranus
Wattled crane, Bugeranus carunculatus
https://en.wikipedia.org/wiki/Common_crane
A medium-sized species, it is the only crane commonly found in Europe besides the demoiselle crane (Anthropoides virgo). Along with the sandhill (Grus canadensis) and demoiselle cranes and the brolga (Grus rubicunda), it is one of only four crane species not currently classified as threatened with extinction or conservation dependent at the species level.
FOUR SPECIES
https://en.wikipedia.org/wiki/Rufous_thrush
The rufous thrushes are medium-sized insectivorous birds in the genus Neocossyphus of the thrush family Turdidae. These are African forest dwelling species. Two species are commonly called "ant-thrushes".
Species[edit]
The following species are currently recognized:[1]
Fraser's rufous thrush, Neocossyphus fraseri (Strickland, 1844)
Finsch's rufous thrush, Neocossyphus finschi (Sharpe, 1870)
Red-tailed ant thrush, Neocossyphus rufus (Fischer & Reichenow, 1884)
White-tailed ant thrush, Neocossyphus poensis (Strickland, 1844)
FOUR MELODIOUS WHISTLES
https://en.wikipedia.org/wiki/Finsch%27s_rufous_thrush
The voice is similar to that of the rufous flycatcher-thrush. In Liberia it sings from May to October.[1] The song is four melodious whistles, "hooee, hooee hooee-huEE, slower and lower-pitched than song of Rufous Flycatcher Thrush".[2] One call is four rapidly repeated notes, "tswe-tswe-tswe-tswe" with the variant "tsw-tsee… tsweeeee"; another is "a long, plaintive whistle wee… weeeee-eee." In alarm caused by predators it gives a "buzzing word-word-word." Unlike the rufous flycatcher-thrush, this species responds to recordings of its call.[1]
FOUR SPECIES
https://en.wikipedia.org/wiki/Cochoa
The cochoas (from cocho, Nepali for Cochoa purpurea)[1] are medium-sized frugivorous, insectivorous and molluscivorous birds in the genus Cochoa. Their bright contrasting plumage patterns, sexual dimorphism and feeding habits made their systematic position difficult to ascertain in early times, Richard Bowdler Sharpe placed them with the Prionopidae in 1879 while many considered them as some kind of aberrant thrush.[2] The genus was previously included in the Old World flycatcher family Muscicapidae but molecular phylogenetic studies have shown that it is more closely related to the thrush family Turdidae.[3][4][5]
These are southeast Asian forest-dwelling species, often found near water.[citation needed] The genus contains the following species:[6]
Purple cochoa, Cochoa purpurea
Green cochoa, Cochoa viridis
Sumatran cochoa, Cochoa beccarii
Javan cochoa, Cochoa azurea
https://en.wikipedia.org/wiki/Pelecaniformes
The Pelecaniformes is an order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed
FOUR SPECIES
https://en.wikipedia.org/wiki/Newtonia_(bird)
Newtonia is a genus of passerine birds containing four species. They were formerly classified in the Old World warbler family Sylviidae or Old World flycatcher family Muscicapidae but have recently been shown to belong to the vanga family Vangidae.[1] They are endemic to Madagascar where they occur in forest or scrubland. They forage in pairs for insects, often joining mixed-species feeding flocks.
List of species in taxonomic order:
Dark newtonia, Newtonia amphichroa
Common newtonia, Newtonia brunneicauda
Archbold's newtonia, Newtonia archboldi
Red-tailed newtonia, Newtonia fanovanae
FOUR GENERA
https://en.wikipedia.org/wiki/Vireo
The vireos /ˈvɪri.oʊz/ make up a family, Vireonidae, of small to medium-sized passerine birds (mostly) restricted to the New World. "Vireo" is a Latin word referring to a green migratory bird, perhaps the female golden oriole, possibly the European greenfinch.[1][2]
The four genera of these birds make up the family Vireonidae, and are believed to be related to the crow-like birds in family Corvidae and the shrikes in family Laniidae. Recent biochemical studies have identified two babbler genera (Pteruthius and Erpornis) which may be Old World members of this family.[6] Observers have commented on the vireo-like behaviour of the Pteruthius shrike-babblers, but apparently no-one suspected the biogeographically unlikely possibility of vireo relatives in Asia.
https://en.wikipedia.org/wiki/Vireolanius
FOUR SPECIES
Vireolanius is a genus of bird in the Vireonidae family. It contains the following species:
Yellow-browed shrike-vireo (Vireolanius eximius)
Slaty-capped shrike-vireo (Vireolanius leucotis)
Chestnut-sided shrike-vireo (Vireolanius melitophrys)
Green shrike-vireo (Vireolanius pulchellus)
https://en.wikipedia.org/wiki/Pelican
FOUR WHITE AND FOUR DARK SPECIES OF PELICANS- TWO GROUPS OF FOUR
Four white-plumaged species tend to nest on the ground, and four brown or grey-plumaged species nest mainly in trees.
The eight living pelican species were traditionally divided into two groups, one containing four ground-nesters with mainly white adult plumage (Australian, Dalmatian, great white, and American white pelicans), and one containing four grey or brown plumaged species which nest preferentially either in trees (pink-backed, spot-billed and brown pelicans), or on sea rocks (Peruvian pelican). The largely marine brown and Peruvian pelicans, formerly considered conspecific,[19] are sometimes separated from the others by placement in the subgenus Leptopelicanus[20] but in fact species with both sorts of appearance and nesting behavior are found in either.
The nest itself is a simple scrape in the ground, in which the bird typically lays three or four eggs- FOUR FEEDINGS STYLES
https://en.wikipedia.org/wiki/File:Sandpiper_nest_with_four_eggs.jpg
There are broadly four feeding styles employed by the sandpipers, although many species are flexible and may use more than one style. The first is pecking with occasional probing, usually done by species in drier habitats that do not have soft soils or mud. The second, and most frequent, method employed is probing soft soils, muds and sands for prey. The third, used by Tringa shanks, involves running in shallow water with the bill under the water chasing fish, a method that uses sight as well as tactile senses. The final method, employed by the phalaropes and some Calidris sandpipers, involves pecking at the water for small prey.[6]
DIVING PETROLS FOUR
https://en.wikipedia.org/wiki/Diving_petrel
The diving petrels are seabirds in the bird order Procellariiformes. There are four very similar species all in the family Procellariidae and genus Pelecanoides (Lacépède, 1799), distinguished only by small differences in the coloration of their plumage and their bill construction. They are only found in the Southern Hemisphere.
Of the four species, two, the Peruvian diving petrel and the Magellanic diving petrel, have highly restricted ranges around South America's coasts, while the common diving petrel and the South Georgia diving petrel range widely across the southern oceans, breeding on islands off New Zealand, Subantarctic islands in the Indian Ocean, and islands in the south Atlantic (like Tristan da Cunha).
The four species are:
Peruvian diving petrel (Pelecanoides garnotii)
Magellanic diving petrel (Pelecanoides magellani)
South Georgia diving petrel (Pelecanoides georgicus)
Common diving petrel (Pelecanoides urinatrix)
FOUR FAMILIES PROCELLARIIFORMES
https://en.wikipedia.org/wiki/Procellariidae
According to the famous DNA hybridization study into avian phylogenetic relationships by Sibley and Ahlquist, the split of the Procellariiformes into the four families occurred around 30 million years ago
The procellariid family is usually broken up into four fairly distinct groups; the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters.
The fulmarine petrels include the largest procellariids, the giant petrels, as well as the two fulmar species, the snow petrel, the Antarctic petrel, and the Cape petrel. The fulmarine petrels are a diverse group with differing habits and appearances, but are linked morphologically by their skull features, particularly the long prominent nasal tubes.
The gadfly petrels, so named due to their helter-skelter flight, are the 37 species in the genus Pterodroma and have traditionally included the two species in the genus Bulweria. The species vary from small to medium sizes, 26–46 cm (10–18 in), and are long winged with short hooked bills. The genus Pterodroma is now split into four sub genera,[6] and some species have been split out of the genus (see below).
The prions comprise six species of true prion in the genus Pachyptila and the closely related blue petrel. Often known in the past as whalebirds, three species have large bills filled with lamellae that they use to filter plankton somewhat as baleen whales do, though the old name derives from their association with whales, not their bills (though "prions" does, deriving from Ancient Greek for "saw"). They are small procellariids, 25–30 cm (9.8–11.8 in), with grey, patterned plumage, all inhabiting the Southern Ocean.
The shearwaters are adapted for diving after prey instead of foraging on the ocean's surface; one species has been recorded diving as deep as 70 m (230 ft). The shearwaters are also well known for the long trans-equatorial migrations undertaken by many species. The shearwaters include the 20 or so species of the genus Puffinus, as well as the five large Procellaria species and the three Calonectris species. While all these three genera are known collectively as shearwaters, the Procellaria are called petrels in their common names. A recent study splits the shearwater genus Puffinus into two separate clades or subgroups, Puffinus and Neonectris. Puffinus are the 'smaller' Puffinus shearwaters (Manx, little and Audubon's shearwaters, for example), and the Neonectris are the 'larger' Puffinus shearwaters (sooty shearwaters, for example); in 2004 it was proposed that Neonectris be split into its own genus, Ardenna.[7] This split into two clades is thought to have occurred soon after Puffinus split from the other procellariids, with the genus originating in the north Atlantic Ocean and the Neonectris clade evolving in the Southern Hemisphere.[8]
https://en.wikipedia.org/wiki/Pseudobulweria
Pseudobulweria is a genus of seabirds in the family Procellariidae
four extant species,
one extinct after 1500
https://en.wikipedia.org/wiki/Mosquito
Like all flies, mosquitoes go through four stages in their lifecycles: egg, larva, pupa, and adult or imago.
FOUR BARBELS FOUR GENERA
https://en.wikipedia.org/wiki/Sturgeon
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. Their evolution dates back to the Triassic some 245 to 208 million years ago.[2] The family is grouped into four genera: Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. Four species may now be extinct.
They also have four barbels—sensory organs that precede their wide, toothless mouths.
Sturgeons are polyploid; some species have four, eight, or 16 sets of chromosomes.[21]
Sturgeons feed non-visually. They are believed to use a combination of sensors, including olfactory, tactile and chemosensory cues detected by the four barbels, and electroreception using their ampullae of Lorenzini.[30]
https://en.wikipedia.org/wiki/Viperidae
Four subfamilies are currently recognised.[2] They are also known as viperids. The name "viper" is derived from the Latin word, vipera, -ae, which means "viper".
FOUR GENERA
https://en.wikipedia.org/wiki/Trogonophidae
Trogonophidae (Palearctic worm lizards or desert ringed lizards) is a small family of amphisbaenians, containing five species in four genera. Trogonophids are found in North Africa, the Horn of Africa, the Arabian Peninsula, and western Iran. They are limbless, carnivorous, lizard-like reptiles highly modified for burrowing. They construct their tunnels with an oscillating motion that forces soil into the walls. Unlike other amphisbaenians, their teeth are fused to their jaws, rather than lying in a groove.[1]
Genera[edit]
Agamodon Peters, 1882 (two species)
Diplometopon Nikolskii, 1907 (monotypic)
Pachycalamus Günther, 1881 (monotypic)
Trogonophis Kaup, 1830 (monotypic)
https://en.wikipedia.org/wiki/Günther%27s_dik-dik
Günther's dik-dik (Madoqua guentheri) is a small antelope found in arid zones of East Africa.
Four subspecies have been proposed based on size and pelage features, but have not yet been verified by genetic analyses.[1]
FOUR SUBFAMILIES
https://en.wikipedia.org/wiki/Tenrec
Species[edit]
The four subfamilies, 10 genera, and 34 species of tenrecs are:[16]
FAMILY TENRECIDAE
Subfamily Geogalinae
Genus Geogale
Large-eared tenrec (Geogale aurita)
Subfamily Oryzorictinae
Genus Limnogale
Web-footed tenrec (Limnogale mergulus)
Genus Microgale
Short-tailed shrew tenrec (Microgale brevicaudata)
Cowan's shrew tenrec (Microgale cowani)
Dobson's shrew tenrec (Microgale dobsoni)
Drouhard's shrew tenrec (Microgale drouhardi)
Dryad shrew tenrec (Microgale dryas)
Pale shrew tenrec (Microgale fotsifotsy)
Gracile shrew tenrec (Microgale gracilis)
Grandidier's shrew tenrec (Microgale grandidieri)
Naked-nosed shrew tenrec (Microgale gymnorhyncha)
Jenkins' shrew tenrec (Microgale jenkinsae)
Northern shrew tenrec (Microgale jobihely)
Lesser long-tailed shrew tenrec (Microgale longicaudata)
Microgale macpheei (extinct)
Major's long-tailed tenrec (Microgale majori)
Montane shrew tenrec (Microgale monticola)
Nasolo's shrew tenrec (Microgale nasoloi)
Pygmy shrew tenrec (Microgale parvula)
Greater long-tailed shrew tenrec (Microgale principula)
Least shrew tenrec (Microgale pusilla)
Shrew-toothed shrew tenrec (Microgale soricoides)
Taiva shrew tenrec (Microgale taiva)
Talazac's shrew tenrec (Microgale talazaci)
Thomas's shrew tenrec (Microgale thomasi)
Genus Oryzorictes
Mole-like rice tenrec (Oryzorictes hova)
Four-toed rice tenrec (Oryzorictes tetradactylus)
Subfamily Potamogalinae
Genus Micropotamogale
Nimba otter shrew (Micropotamogale lamottei)
Ruwenzori otter shrew (Micropotamogale ruwenzorii)
Genus Potamogale
Giant otter shrew (Potamogale velox)
Subfamily Tenrecinae
Genus Echinops
Lesser hedgehog tenrec (Echinops telfairi)
Genus Hemicentetes
Highland streaked tenrec (Hemicentetes nigriceps)
Lowland streaked tenrec (Hemicentetes semispinosus)
Genus Setifer
Greater hedgehog tenrec (Setifer setosus)
Genus Tenrec
Common tenrec (Tenrec ecaudatus)
FOUR LIFE STAGES
https://en.wikipedia.org/wiki/Rodent
Brown rats use social learning in a wide range of situations, but perhaps especially so in acquiring food preferences. Learning about suitable foods can be divided into four life stages.[82][83]
Before birth: In utero, fetal rats detect odor-bearing particles that come from their mother's diet and cross the placental barrier. Shortly after birth, newborn rats respond positively to these foods.[82][83]
During nursing: Nursing rats receive information about their mother's diet through her milk. They prefer the foods she ate during lactation.[82][83]
Weaning: When young rats are weaning and eating solid foods for the first time, they use adult rats as guides. They forage where the adults are foraging or where adults have previously scent-marked.[82][83]
Adolescence and adulthood: When rats forage on their own, their food choices are influenced by social interactions that may take place far away from foraging sites. They smell foods on the fur, whiskers and especially the breath of other rats and strongly prefer the foods those rats had previously eaten.[82] This inclines them not to eat poisons avoided by older rats.[83]
FOUR HUMANOID FIGURES
https://en.wikipedia.org/wiki/Carl_Linnaeus
https://en.wikipedia.org/wiki/File:Hoppius_Anthropomorpha.png
Anthropomorpha depicted in Hoppius' Amoenitates Academicae (1763)
1. Troglodyta Bontii, 2. Lucifer Aldrovandi, 3. Satyrus Tulpii, 4. Pygmaeus Edwardi
CD4 FOUR DOMAINS
https://en.wikipedia.org/wiki/CD4
Like many cell surface receptors/markers, CD4 is a member of the immunoglobulin superfamily.
It has four immunoglobulin domains (D1 to D4) that are exposed on the extracellular surface of the cell:
D1 and D3 resemble immunoglobulin variable (IgV) domains.
D2 and D4 resemble immunoglobulin constant (IgC) domains.
I'm a paragraph. Click here
The eastern newt includes these four subspecies:[5]
https://en.wikipedia.org/wiki/Eastern_newt
Red-spotted newt (N. v. viridescens)
Broken-striped newt (N. v. dorsalis)
Central newt (N. v. louisianensis)
Peninsula newt (N. v. piaropicola)
to add your own text and edit me. It's easy.
FOUR ACTIONS
https://en.wikipedia.org/wiki/Physical_examination
Four actions are taught as the basis of physical examination: inspection, palpation (feel), percussion (tap to determine resonance characteristics), and auscultation (listen).
https://en.wikipedia.org/wiki/Percussion_(medicine)
There are four types of percussion sounds: resonant, hyper-resonant, stony dull or dull. A dull sound indicates the presence of a solid mass under the surface.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Leaf
Rows
The term, distichous, literally means two rows. Leaves in this arrangement may be alternate or opposite in their attachment. The term, 2-ranked, is equivalent. The terms, tristichous and tetrastichous, are sometimes encountered. For example, the "leaves" (actually microphylls) of most species of Selaginella are tetrastichous, but not decussate
FOUR SETS OF WAX GLANDS
https://en.wikipedia.org/wiki/Worker_bee
Wax production (days 12–17)[edit]
Wax bees build cells from wax, repair old cells, and store nectar and pollen brought in by other workers. Early in the worker's career she will exude wax from the space between several of her abdominal segments. Four sets of wax glands, situated inside the last four ventral segments of the abdomen, produce wax for comb construction.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetracycline_antibiotics
Tetracyclines are broad-spectrum antibiotics whose general usefulness has been reduced with the onset of antibiotic resistance. Despite this, they remain the treatment of choice for some specific indications.
They are so named for their four ("tetra-") hydrocarbon rings ("-cycl-") derivation ("-ine"). To be specific, they are defined as "a subclass of polyketides having an octahydrotetracene-2-carboxamide skeleton".[1] They are collectively known as "derivatives of polycyclic naphthacene carboxamide".
FANS OUT INTO FOUR TENDONS
https://en.wikipedia.org/wiki/Flexor_digitorum_profundus_muscle
Flexor digitorum profundus originates in the upper 3/4 of the anterior and medial surfaces of the ulna, interosseous membrane and deep fascia of the forearm. The muscle fans out into four tendons (one to each of the second to fifth fingers) to the palmar base of the distal phalanx.
TETRAPYRROLES- TETRA IS FOUR
https://en.wikipedia.org/wiki/Bilin_(biochemistry)
Bilins, bilanes or bile pigments are biological pigments formed in many organisms as a metabolic product of certain porphyrins. Bilin (also called bilichrome) was named as a bile pigment of mammals, but can also be found in lower vertebrates, invertebrates, as well as red algae, green plants and cyanobacteria. Bilins can range in color from red, orange, yellow or brown to blue or green.
In chemical terms, bilins are linear arrangements of four pyrrole rings (tetrapyrroles). In human metabolism, bilirubin is a breakdown product of heme. Hydroxymethyl bilane is a major anabolic product, from the biosynthetic reaction of porphobilinogen (PBG) and uroporphyrinogen I synthase (known as porphobilinogen deaminase).
FOUR BRANCHES
https://en.wikipedia.org/wiki/Thoracoacromial_artery
The thoracoacromial artery (acromiothoracic artery; thoracic axis) is a short trunk that arises from the forepart of the axillary artery, its origin being generally overlapped by the upper edge of the Pectoralis minor.
Contents [hide]
1 Branches
2 Mnemonic
3 Additional images
4 References
5 External links
Branches[edit]
Projecting forward to the upper border of the Pectoralis minor, it pierces the coracoclavicular fascia and divides into four branches—pectoral, acromial, clavicular, and deltoid.
Branch Description
Pectoral branch Descends between the two Pectorales, and is distributed to them and to the mamma, anastomosing with the intercostal branches of the internal thoracic artery and with the lateral thoracic.
Acromial branch Runs laterally over the coracoid process and under the Deltoideus, to which it gives branches; it then pierces that muscle and ends on the acromion in an arterial network formed by branches from the transverse scapular (a.k.a. suprascapular), thoracoacromial, and posterior humeral circumflex arteries.
Clavicular branch Runs upward and medialward to the sternoclavicular joint, supplying this articulation, and the Subclavius.
Deltoid (humeral) branch Often arising with the acromial, it crosses over the Pectoralis minor and passes in the same groove as the cephalic vein, between the Pectoralis major and Deltoideus, and gives branches to both muscles.
Mnemonic[edit]
Mnemonics used to remember the four branches are:
"ABCD where Breast"
"Cadavers Are Dead People" or "CADP" where P (pectoral).[1]
"All Dogs Can Pee" or "ADCP" where P (pectoral).[2]
"CAlifornia Police Department" or "CAPD"
"packed" or "PACD"
https://en.wikipedia.org/wiki/Ligand-gated_ion_channel
THESE ARE PENTAMERIC BUT EACH SUBUNIT CONTAINS FOUR TRANSMEMBRANE HELICES THIS TIME- SO I SHOWED YOU WITH CALCIUM CHANNELS THERE ARE FOUR DOMAINS EACH WITH SIX PARTS- HERE THERE IS FIVE PENTAMERIC BUT EACH CONTAINS FOUR- SO THE FOUR HAS REMAINED DOMINANT
They are usually pentameric with each subunit containing 4 transmembrane helices constituting the transmembrane domain, and a beta sheet sandwich type, extracellular, N terminal, ligand binding domain.
Cys-loop receptors have structural elements that are well conserved, with a large extracellular domain (ECD) harboring an alpha-helix and 10 beta-strands. Following the ECD, four transmembrane segments (TMSs) are connected by intracellular and extracellular loop structures
https://en.wikipedia.org/wiki/Chlamydia_trachomatis
Chlamydia trachomatis (/kləˌmɪdiə/ /trəˈkoʊmətᵻs/), commonly known as chlamydia,[2] is one of four bacterial species in the genus Chlamydia.
FOUR TYPES DISEASE
https://en.wikipedia.org/wiki/Necrotizing_fasciitis
The disease is classified into four types, depending on the infecting organism.[4] The most common type is caused by a mixture of bacterial types, and commonly occurs at sites of surgery or trauma, usually in abdominal or perineal areas and accounts for 70 to 80% of cases.[4][18] Type II is caused by Group A streptococci (often with a co-infection of S. aureus), and usually occurs on the head, neck, arm or legs. It is less often associated with predisposing risk factors (such as surgery or a compromised immune system). Type III is caused by Vibrio vulnificus, which enters the skin via puncture wounds from fish or insects in seawater.[19][20] Type four is due to a fungal infection.[4]
FOUR HORNS
https://en.wikipedia.org/wiki/Tetrameryx
Tetrameryx is an extinct genus of the North American artiodactyl family Antilocapridae, known from Mexico,[2] the western United States, and Saskatchewan.[1] The name means "four [horned] ruminant", referring to the division of each horn near its base into two prongs; in T. shuleri, the rear prong is much longer.[3]
One member of the genus, T. shuleri, survived until about 12,000 years ago, and was present when Paleo-Indians reached North America.[4]
FOUR SPECIES
https://en.wikipedia.org/wiki/Rusa_(genus)
Rusa is a genus of deer from southern Asia. They have traditionally been included in Cervus, and genetic evidence suggests this may be more appropriate than their present placement in a separate genus.[1]
Three of the four species have relatively small distributions in the Philippines and Indonesia, but the Sambar is more widespread, ranging from India east and north to China and south to the Greater Sundas. All are threatened by habitat loss and hunting in their native ranges, but three of the species have also been introduced elsewhere.
Species[edit]
Rusa alfredi – Visayan spotted deer, Philippine Spotted Deer
Rusa marianna – Philippine Brown Deer or Philippine Sambar
Rusa timorensis – Javan Rusa or Sunda Sambar
Rusa unicolor – Sambar
https://en.wikipedia.org/wiki/Cervus
The sika deer should be split into four species based on genetics, morphology and voice
FOUR FAMILIES
https://en.wikipedia.org/wiki/Dysderoidea
https://en.wikipedia.org/wiki/Caponiidae
The Dysderoidea are a clade or superfamily of araneomorph spiders. The monophyly of the group, initially consisting of the four families Dysderidae, Oonopidae, Orsolobidae and Segestriidae,[2] has consistently been recovered in phylogenetic studies.[
CALLED UNLIKE ANY OF THE FOUR
https://en.wikipedia.org/wiki/Père_David%27s_deer
The species is sometimes known by its informal name sibuxiang (Chinese: 四不像; pinyin: sì bú xiàng; Japanese: shifuzō), literally meaning "four not alike", which could mean "the four unlikes" or "like none of the four"; it is variously said that the four are cow, deer, donkey, horse (or) camel, and that the expression means in detail:
"the hooves of a cow but not a cow, the neck of a camel but not a camel, antlers of a deer but not a deer, the tail of a donkey but not a donkey."
"the nose of a cow but not a cow, the antlers of a deer but not a deer, the body of a donkey but not a donkey, tail of a horse but not a horse"
"the tail of a donkey, the head of a horse, the hoofs of a cow, the antlers of a deer"
"the neck of a camel, the hoofs of a cow, the tail of a donkey, the antlers of a deer"
"the antlers of a deer, the head of a horse and the body of a cow"[6]
By this name, this undomesticated animal entered Chinese mythology as the mount of Jiang Ziya in Fengshen Bang (translated as Investiture of the Gods), a Chinese classical work of fiction written during the Ming Dynasty.
FOUR SPECIES
https://en.wikipedia.org/wiki/Bipedidae
Bipedidae is a family of amphisbaenian lizards that includes the extant genus Bipes represented by four species from Mexico and the extinct genus Anniealexandria represented by one species that lived in what is now Wyoming during the earliest Eocene approximately 55 million years ago. Phylogenetic analysis indicates that Bipedidae is most closely related to the family Blanidae, which includes the living genus Blanus.[1]
http://animal-world.com/encyclo/reptiles/information/lizardclassfamilies.php
Four Horned Chameleon - Chamaeleo quadricornus
https://en.wikipedia.org/wiki/List_of_mammal_genera
Artiodactyla is a large order of hoofed mammals, the even-toed ungulates. They are found nearly cosmopolitan, although no species are native to Australia or Antarctica. Broken into four suborder, Tylopoda (including Camelidae), Suina (including Suidae and Tayassuidae), Whippomorpha (including Hippopotamidae), and Ruminantia, which contains two Infraorders, Tragulina (including Tragulidae) and Pecora (including Moschidae, Cervidae, Bovidae, Antilocapridae, and Giraffidae).
Much variation occurs in the coat colour of the species, with four main variants: common, menil, melanistic, and leucistic – a genuine colour variety, not albinistic.[6] The white is the lightest coloured, almost white; common and menil are darker, and melanistic is very dark, sometimes even black (easily confused with the sika deer).
https://en.wikipedia.org/wiki/Fallow_deer
Common: Chestnut coat with white mottles, it is most pronounced in summer with a much darker, unspotted coat in the winter. The light-coloured area around the tail is edged with black. The tail is light with a black stripe.
Menil: Spots are more distinct than common in summer and no black is seen around the rump patch or on the tail. In winter, spots are still clear on a darker brown coat.
Melanistic (black): All-year the coat is black shading to greyish brown. No light-coloured tail patch or spots are seen.
Leucistic (white, but not albino): Fawns are cream-coloured; adults become pure white, especially in winter. Dark eyes and nose are seen, with no spots.[7]
Four subspecies of the tufted deer are recognized- FOURTH ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Tufted_deer
E. c. cephalophus – the largest subspecies, brownish coat, found in southwestern China and northeastern Myanmar.
E. c. michianus – has a relatively narrow snout, found in southeastern China.
E. c. ichangensis – has a relatively broad snout and a greyish coat, found in Central China.[2]
E. c. forciensus – doubtful subspecies, distribution unclear.[1]
THERE ARE FOUR CLASSES OF TETRAPOD
https://en.wikipedia.org/wiki/Tetrapod
Tetrapoda includes four classes: amphibians, reptiles, mammals, and birds.
FOUR TEATS
https://en.wikipedia.org/wiki/Chinese_goral
The Chinese goral is intermediate between an antelope and a goat and grows to a shoulder height of 50 to 78 cm (20 to 31 in) and length of 82 to 130 cm (32 to 51 in). It is stockily built with long, stout limbs and broad hooves. The horns are short and conical and the ears fairly long and pointed. The four teats are in contrast to sheep and goats which normally have two.
FOUR GENERA
https://en.wikipedia.org/wiki/Marattiaceae
There have long been four traditional extant genera (Angiopteris, Christensenia, Danaea and Marattia)
https://en.wikipedia.org/wiki/Dik-dik
A dik-dik is the name for any of four species of small antelope in the genus Madoqua that live in the bushlands of eastern and southern Africa.
The four species of dik-dik are:[1]
Madoqua gunther (Günther, 1894) – Günther's dik-dik
M. kirkii (Günther, 1880) – Kirk's dik-dik
M. piacentinii (Drake–Brockman, 1911) – Silver dik-dik
M. saltiana (Desmarest, 1816) – Salt's dik-dik
FOUR SPECIES
https://en.wikipedia.org/wiki/Goral
The gorals are four species in the genus Nemorhaedus or Naemorhedus. They are small ungulates with a goat-like or antelope-like appearance.
The original name is based on Latin nemor-haedus, from nemus, nemoris 'grove' and haedus 'little goat', but was misspelt Naemorhedus by Hamilton Smith (1827).[2][3]
Until recently, this genus also contained the serow species (now in genus Capricornis).[1] The name "goral" comes from an eastern Indian word for the Himalayan goral. The four species of gorals are:
The Himalayan goral (also known as ghural), Naemorhedus goral, is native to northwestern and northeastern India, as well as Nepal and Bhutan.
The long-tailed goral, Naemorhedus caudatus, can be found in eastern Russia and China through western Thailand and eastern Myanmar. A population has also been documented in the Demilitarized Zone on the Korean Peninsula.
The red goral, Naemorhedus baileyi, inhabits areas from the Yunnan province of China, to Tibet and northeastern India through northern Myanmar.
The Chinese goral, Naemorhedus griseus, is distributed through Burma, China, India, Thailand, Vietnam, and possibly Laos.
https://en.wikipedia.org/wiki/Kirk%27s_dik-dik
Kirk's dik-dik (Madoqua kirkii) is a small antelope native to Eastern Africa and one of four species of dik-dik antelope
Usually, four subspecies of Kirk's dik-dik are distinguished, but in fact they may represent three or more distinct species:[11]
M. k. kirkii Günther, 1880
M. k. cavendishi Thomas, 1898 – Cavendish's dik-dik
M. k. damarensis Günther, 1880 – Damara dik-dik
M. k. hindei Thomas, 1898
FOUR GENERA
https://en.wikipedia.org/wiki/Alcelaphinae
The subfamily Alcelaphinae of the family Bovidae contains wildebeest, hartebeest, bonteboks and several similar species. Depending on the classification, there are either seven, nine or ten species in four genera
FOUR SPECIES
https://en.wikipedia.org/wiki/Eudorcas
Eudorcas is a genus of antelope; the species are commonly called gazelles. Eudorcas was originally considered a subgenus of the genus Gazella but has since been elevated to generic status.[1] The four species within the genus Eudorcas are:
Genus Eudorcas[1]
Mongalla gazelle, E. albonotata
Red-fronted gazelle, E. rufifrons
E. r. kanuri
E. r. laevipes
E. r. rufifrons
E. r. tilonura, Heuglin's gazelle[2]
Red gazelle, E. rufina
Thomson's gazelle, E. thomsonii
E. t. nasalis
E. t. thomsonii
https://en.wikipedia.org/wiki/Red_rock_hare
FOUR SPECIES
The red rock hares are the four species in the genus Pronolagus.[1] They are African lagomorphs of the family Leporidae.
This genus contains the following species:
Natal red rock hare, Pronolagus crassicaudatus
Jameson's red rock hare, Pronolagus randensis
Smith's red rock hare, Pronolagus rupestris
Hewitt's red rock hare, Pronolagus saundersiae (used to be included in Pronolagus rupestris)
https://en.wikipedia.org/wiki/Japanese_hare
FOUR SUBSPECIES
Coenraad Jacob Temminck described the Japanese hare in 1845. The species name is derived from the Ancient Greek brachys "short" and ouros "tail".
The four subspecies of this hare are:
L. b. angustidens
L. b. brachyurus
L. b. lyoni
L. b. okiensis
There are four distinct subspecies of Struthio camelus that each occupy their own niche. Previously there would have been five subspecies, but Struthio molybdophanes is now considered a unique species.
http://tolweb.org/treehouses/?treehouse_id=4734
Struthio camelus australis - Commonly called the Southern Ostrich because it is found exclusively in Southern Africa. Lives in a range independent of all other supspecies of ostrich.
Struthio camelus camelus - The largest and most widespread of the ostrich subspecies. Commonly called the North African Ostrich or the Red-necked Ostrich.
Struthio camelus massaicus - This subspecies, referred to as the Masai Ostrich, lives in Eastern Africa and is easily identified by the bright orange neck and thighs of the males.
Struthio camelus syriacus - Endemic to the Arabian Peninsula, Syria, and Iraq, the Arabian or Middle Eastern Ostrich used to be very common. Due to overhunting and habitat restrictions, this subspecies became extinct around 1966.
FOUR FORMS
https://en.wikipedia.org/wiki/Llama
The question is complicated by the circumstance of the great majority of individuals that have come under observation being either in a completely or partially domesticated state. Many are also descended from ancestors that have previously been domesticated, a state that tends to produce a certain amount of variation from the original type. The four forms commonly distinguished by the inhabitants of South America are recognized as distinct species, though with difficulties in defining their distinctive characteristics.
These are:
the llama, Lama glama (Linnaeus);
the alpaca, Vicugna pacos (Linnaeus);
the guanaco (from the Quechua huanaco), Lama guanicoe (Müller); and
the vicuña, Vicugna vicugna (Molina)
https://en.wikipedia.org/wiki/Common_raven
Linguist Derek Bickerton, building on the work of biologist Bernd Heinrich, has argued that ravens are one of only four known animals (the others being bees, ants, and humans) who have demonstrated displacement, the capacity to communicate about objects or events that are distant in space or time from the communication
FOUR SUBORDERS
https://en.wikipedia.org/wiki/Eel
An eel is any fish belonging to the order Anguilliformes (/æŋˌɡwɪlᵻˈfɔːrmiːz/), which consists of four suborders, 20 families, 111 genera and about 800 species
Suborders and families[edit]
A moray eel
Gorgasia barnesi, a species of garden eel
Juvenile American eels
Suborder Anguilloidei
Anguillidae (freshwater eels)
Chlopsidae (false morays)
Heterenchelyidae (mud eels)
Moringuidae (spaghetti eels)
Muraenidae (moray eels)
Myrocongridae (thin eels)
Protanguillidae
Suborder Congroidei
Colocongridae (worm eels)
Congridae (congers)
Including Macrocephenchelyidae
Derichthyidae (longneck eels)
Including Nessorhamphidae
Muraenesocidae (pike congers)
Nettastomatidae (duckbill eels)
Ophichthidae (snake eels)
Suborder Nemichthyoidei
Nemichthyidae (snipe eels)
Serrivomeridae (sawtooth eels)
Suborder Synaphobranchoidei
Synaphobranchidae (cutthroat eels)
Including Dysommidae, Nettodaridae, and Simenchelyidae
In some classifications, the family Cyematidae of bobtail snipe eels is included in the Anguilliformes, but in the FishBase system that family is included in the order Saccopharyngiformes.
The electric eel of South America is not a true eel, but is a South American knifefish more closely related to the carps and catfishes.
Bassanago is a genus of marine congrid eels.
https://en.wikipedia.org/wiki/Bassanago
Species[edit]
There are currently four recognized species in this genus:[1]
Bassanago albescens (Barnard, 1923) (Deepsea conger)
Bassanago bulbiceps Whitley, 1948 (Swollen-headed conger eel)
Bassanago hirsutus (Castle, 1960) (Hairy conger)
Bassanago nielseni (Karmovskaya, 1990)
CHIMPANZEE SOUNDS FOUR PARTS
https://en.wikipedia.org/wiki/Common_chimpanzee
Pant-hoots are made of four parts, starting with soft "hoos" that get louder and louder and climax into screams and sometimes barks; the former die down to soft "hoos" again as the call ends.[53] Submissive individuals will make "pant-grunts" towards their superiors.[21][44] Chimps use distance calls to draw attention to danger, food sources, or other community members.[21] "Barks" may be made as "short barks" when hunting and "tonal barks" when sighting large snakes
FOUR SUBSPECIES OF ORANGUTAN
http://www.centerforgreatapes.org/treatment-apes/about-apes/
There are four sub-species of orangutan:
in Sumatra: pongo abelli
in Borneo: pongo pygmaeus pygmaeus, pongo pygmaeus wurmbii, pongo pygmaeus morio
GORILLA FOUR SUBSPECIES
https://en.wikipedia.org/wiki/Gorilla
Genus Gorilla
Western gorilla (G. gorilla)
Western lowland gorilla (G. g. gorilla)
Cross River gorilla (G. g. diehli)
Eastern gorilla (G. beringei)
Mountain gorilla (G. b. beringei)
Eastern lowland gorilla (G. b. graueri)
FOUR BLOODLINES
https://en.wikipedia.org/wiki/Morgan_horse
The Morgan horse is one of the earliest horse breeds developed in the United States.[1] Tracing back to the foundation sire Figure, later named Justin Morgan after his best-known owner, Morgans served many roles in 19th-century American history, being used as coach horses and for harness racing, as general riding animals, and as cavalry horses during the American Civil War on both sides of the conflict. Morgans have influenced other major American breeds, including the American Quarter Horse, Tennessee Walking Horse and the Standardbred. During the 19th and 20th centuries, they were exported to other countries, including England, where a Morgan stallion influenced the breeding of the Hackney horse. In 1907, the US Department of Agriculture established the US Morgan Horse Farm near Middlebury, Vermont for the purpose of perpetuating and improving the Morgan breed; the farm was later transferred to the University of Vermont. The first breed registry was established in 1909, and since then many organizations in the US, Europe and Oceania have developed. There were estimated to be over 175,000 Morgan horses worldwide in 2005.
There are four main bloodlines groups within the Morgan breed today, known as the Brunk, Government, Lippitt, and Western Working "families." There are also smaller subfamilies. The Brunk Family, particularly noted for soundness and athleticism, traces to the Illinois breeding program of Joseph Brunk. The Lippitt Family or "Lippitts" trace to the breeding program of Robert Lippitt Knight,[1] grandson of industrialist Robert Knight and maternal great-great grandson of Revolutionary War officer Christopher Lippitt, founder of the Lippitt Mill.[26] Robert Lippitt Knight focused on preservation breeding of horses descended from Ethan Allen II and this line is considered the "purest" of the four lines, with the most lines tracing back to Figure and no outcrosses to other breeds in the 20th or 21st centuries.[27] The Government Family is the largest, tracing to Morgans bred by the US Morgan Horse Farm between 1905 and 1951. The foundation sire of this line was General Gates.[1] When USDA involvement ended, the University of Vermont purchased not only the farm,[20] but much of its breeding stock and carries on the program today. The Working Western Family, abbreviated 2WF, have no common breeder or ancestor, but are the horses bred to be stock horses and work cattle, some descended from Government farm stallions shipped west.[1]
Paris quadrifolia, the herb-paris[3] or true lover's knot, is a Eurasian species of flowering plant in the family Melanthiaceae, although authorities formerly regarded it as part of the Liliaceae family. It is related to Trillium, with which it can be confused. Trillium, however, is generally 3-merous (3 leaves per whorl, 3 petals etc.), whereas Paris quadrifolia is 4-merous.[1]
https://en.wikipedia.org/wiki/Paris_quadrifolia
Contents [hide]
1 Characteristics
2 Gallery
3 References
4 External links
Characteristics[edit]
Paris quadrifolia has solitary flowers with four or more very narrow greenish filiform (threadlike) petals, green petaloid sepals, eight stamens, and a round purple to red ovary in the center. The flower is borne above a single whorl of four or more stem leaves. It prefers calcareous soils and lives in damp and shady places, especially old established woods and streamsides. It occurs locally in temperate and cool areas throughout Europe and northern Asia from Spain to Yakutia and northern China, but is absent in the wild from the Americas, Africa and the southern hemisphere. In Britain it is more frequently found in the east of the country, but it is uncommon throughout its range.[1][4][5]
http://leavingbio.net/blood.htm
Qmr i put this in my first book blood is made of four components
Blood is made of four components:
Plasma is a pale yellow sticky liquid. It makes up 55% of the blood’s volume. The components of plasma are water 92%, dissolved protein 8%, glucose, amino acids, vitamins, minerals, urea, uric acid, CO2, hormones, antibodies. Plasma carries dissolved materials such as glucose, amino acids, minerals, vitamins, salts, carbon dioxide, urea, and hormones. It also carries heat energy.
Red Blood Cells, also called erythrocytes, are tiny biconcave disc-shaped cells. They do not have a nucleus or mitochondria. Their cytoplasm is rich in haemoglobin. O2 binds to the iron in haemoglobin. Red blood cells are made in the bone marrow. They survive for about four months. They are destroyed and recycled by the liver and spleen. They are destroyed because they have to constantly change shape to pass through narrow blood vessels. When they die the haemoglobin is stored in the liver and used to make new blood cells in the bone marrow. They are very small. There are about 5 million red blood cells in 1 cc. of blood. The rest that is not stored is converted into bile pigments.
Red Blood Cells transport oxygen. Haemoglobin has a base of iron. The iron joins with oxygen in areas of high oxygen concentration (in the lungs and releases oxygen in areas of low oxygen concentration in the body cells.
Anaemia is the lack of haemoglobin or red blood cells. The symptoms of anaemia are pale skin colour and a loss of energy.
SEM Image of Blood Cells
RED BLOOD CELL PLATELET WHITE BLOOD CELL
White Blood Cells (leucocytes) are colourless cells and possess a nucleus. They function in defending the body against pathogens. Some ‘feed’ on pathogens by phagocytosis. These white blood cells are called phagocytes. Others, the lymphocytes produce antibodies, the specific defense proteins. They are made by the bone marrow and lymphatic tissue.
A white blood cell ingests a pathogen by phagocytosis.
TYPES OF WHITE BLOOD CELLS
Lymphocytes
Lymphocytes are made in the bone marrow and then stored in various in various parts of the lymphatic system. Their main function is to make antibodies.
Monocytes
Monocytes are large cells that digest bacteria and other particles. They are also called macrophages. They have kidney shaped nuclei.
Platelets, also called thrombocytes, are tiny fragments of large bone marrow cells. They carry specialised blood clotting chemicals. The clotting chemicals are released where blood and lymph vessels are injured. A nucleus is not present in platelets.
FOUR SUBUNITS
https://en.wikipedia.org/wiki/Cohesin
Cohesin is a multi-subunit protein complex, made up of four core subunits: two SMC proteins (SMC1 and 3), an alpha-kleisin (orthologues of yeast Scc1), and an orthologue of the yeast Scc3 protein (e.g. STAG1-3 in humans and SA1-3 in mice).
https://en.wikipedia.org/wiki/Four-eyed_turtle
The four-eyed turtle[2] (Sacalia quadriocellata) is a reptile of the order Testudines. Its name refers to two bright yellow or green spots that occur on the back of its head that can look like another pair of eyes.
FOUR GENERA INFECT HUMANS
https://en.wikipedia.org/wiki/Chordopoxvirinae
Chordopoxvirinae is a subfamily of viruses, in the family Poxviridae. Humans, vertebrates, and arthropods serve as natural hosts. There are currently 38 species in this subfamily, divided among 10 genera. Diseases associated with this subfamily include: Variola virus: smallpox.[1][2]
Four genera in this subfamily contain species that infect humans: Molluscipoxvirus, Orthopoxvirus, Parapoxvirus and Yatapoxvirus.
FOUR GENERA
https://en.wikipedia.org/wiki/Onocleaceae
Onocleaceae is a small family of terrestrial ferns in the Polypodiales order of the Polypodiopsida class.[1] The family may contain from one to four genera of onocleoids, consisting of five species largely in north temperate climes. The four genera: Matteuccia, Onoclea, Onocleopsis, and Pentarhizidium may be included under the single genus Onoclea.[2]
Five species, in four genera [4]
Matteuccia struthiopteris (ostrich fern) - wide distribution including North America, Europe, and Asia
Onoclea sensibilis (sensitive fern) - North America and eastern Asia, with the American and Asian populations being recognized as distinct varieties
Onocleopsis hintonii - found in a restricted range of wet mountain canyons in southern Mexico and Guatemala; some botanists (especially Masahiro Kato) consider this to be a species of Matteuccia
Pentarhizidium
Pentarhizidium orientale - eastern Asia as far south as the Himalayas
Pentarhizidium intermedium - China to India
FOUR SUBSPECIES OF OSTRICH
https://en.wikipedia.org/wiki/Common_ostrich
Subspecies
Four living subspecies are recognised:
Common ostrich (S. camelus) complex:
Subspecies of common ostrich
Subspecies Description Image
North African ostrich (S. c. camelus), also called the red-necked ostrich or Barbary ostrich Lives in North Africa. Historically it was the most widespread subspecies, ranging from Ethiopia and Sudan in the east throughout the Sahel[22] to Senegal and Mauritania in the west, and north to Egypt and southern Morocco, respectively. It has now disappeared from large parts of this range,[23] and it only remains in 6 of the 18 countries where it originally occurred, leading some to consider it Critically Endangered.[24] It is the largest subspecies, at 2.74 m (9.0 ft) in height and up to 154 kilograms (340 lb) in weight.[25] The neck is pinkish-red, the plumage of males is black and white, and the plumage of females is grey.[25]
Northern Africa: Algeria, Central African Republic, Chad, Egypt, Ethiopia, Libya, Mali, Mauritania, Morocco, South Sudan, Sudan, Togo and Tunisia
Western Africa: Benin, Burkina Faso, Cameroon, Ghana, Niger, Nigeria and Senegal
Yaen001.jpg
South African ostrich (S. c. australis), also commonly known as black-necked ostrich or southern ostrich Is found south of the rivers Zambezi and Cunene. It is farmed for its meat, leather and feathers in the Little Karoo area of Cape Province.[26]
Southern Africa: Angola, Botswana, Democratic Republic of the Congo, Namibia, South Africa, Zambia and Zimbabwe
Ostrich (Struthio camelus) male (13994461256).jpg
Masai ostrich (S. c. massaicus), also known as the pink-necked ostrich or East African ostrich It has some small feathers on its head, and its neck and thighs are pink. During the mating season, the male's neck and thighs become brighter. Its range is essentially limited to southern Kenya and eastern Tanzania[22] and Ethiopia and parts of southern Somalia.[25]
Eastern Africa: Burundi, Democratic Republic of the Congo, Ethiopia, Kenya, Rwanda, Somalia, Tanzania and Uganda
Ostrich Struthio camelus Tanzania 3742 cropped Nevit.jpg
Arabian ostrich (daggerS. c. syriacus), also known as Syrian ostrich or Middle Eastern ostrich Was formerly very common in the Arabian Peninsula, Syria,[22] and Iraq; it became extinct around 1966.
Western Asia: Iran, Iraq, Israel, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, Syria, United Arab Emirates, Yemen and Turkey
FOUR GENERA
https://en.wikipedia.org/wiki/Schizaeaceae
Schizaeaceae is a family with three subfamilies, Anemioideae, Lygodioideae and Schizaeoideae (sometimes treated as families), with a total of four genera and about 190 species
FOUR SPECIES
https://en.wikipedia.org/wiki/Uroconger
Uroconger is a genus of eels in the family Congridae. It currently contains the following species:
Uroconger drachi (Blache & Bauchot, 1976)
Uroconger erythraeus Castle, 1982
Uroconger lepturus (J. Richardson, 1845) (Slender conger)
Uroconger syringinus Ginsburg, 1954 (Threadtail conger)
FOUR SUBSPECIES COMMON CHIMPANZEE
https://en.wikipedia.org/wiki/Common_chimpanzee
Four subspecies of the common chimpanzee have been recognised,[11][12] with the possibility of a fifth:[13]
Central chimpanzee or tschego, P. t. troglodytes, in Cameroon, the Central African Republic, Equatorial Guinea, Gabon, the Republic of the Congo, and the Democratic Republic of the Congo
Western chimpanzee, P. t. verus, in Guinea, Guinea Bissau, Mali, Senegal, Sierra Leone, Liberia, Ivory Coast, and Ghana
Nigeria-Cameroon chimpanzee, P. t. ellioti (also known as P. t. vellerosus),[11] in Nigeria and Cameroon
Eastern chimpanzee, P. t. schweinfurthii, in the Central African Republic, South Sudan, the Democratic Republic of the Congo, Uganda, Rwanda, Burundi, Tanzania, and Zambia
Southeastern chimpanzee, P. t. marungensis, in Burundi, Rwanda, Tanzania, and Uganda: Colin Groves argues that this subspecies is the result of enough variation between the northern and southern populations of P. t. schweinfurthii.[13]
There are four distinct populations of chimpanzees in Africa:
http://www.centerforgreatapes.org/treatment-apes/about-apes/
Pan troglodytes troglodytes (central Africa)
Pan troglodytes vellerosus (Cameroon and Nigeria)
Pan troglodytes verus (western Africa)
Pan troglodytes schweinfurthii (eastern Africa)
FOUR SPECIES GREAT APES FOUR SUBSPECIES GORILLA
http://www.defenders.org/gorilla/basic-facts
Closely linked by DNA, gorillas (family Hominidae) are one of the four species of great apes that are the closest living relatives of humans – the other three are chimpanzees, bonobos and orangutans. Great apes are different from monkeys for a variety of reasons: they are larger, walk upright for a longer period of time, don’t have tails and have much larger, more developed brains.
There are four subspecies of gorillas: the eastern lowland or Grauer’s gorilla (Gorilla beringei graueri); the mountain gorilla (Gorilla beringei beringei); the western lowland gorilla (Gorilla gorilla gorilla); and the Cross River gorilla (Gorilla gorilla diehl).
FOUR SUBSPECIES-In modern times, four U.S. states have named the painted turtle their official reptile.
https://en.wikipedia.org/wiki/Painted_turtle
https://en.wikipedia.org/wiki/File:Painted_Turtle_Distribution_alternate.svg
Four regionally based subspecies (the eastern, midland, southern, and western) evolved during the last ice age.
The borders between the four subspecies are not sharp, because the subspecies interbreed. Many studies have been performed in the border regions to assess the intermediate turtles, usually by comparing the anatomical features of hybrids that result from intergradation of the classical subspecies.[nb 5] Despite the imprecision, the subspecies are assigned nominal ranges.
The painted turtle (C. picta) is the only species in the genus Chrysemys.[5] The parent family for Chrysemys is Emydidae: the pond turtles. Emydidae is split into two sub families; Chrysemys is part of the Deirochelyinae (Western Hemisphere) branch.[117] The four subspecies of the painted turtle are the eastern (C. p. picta), midland (C. p. marginata), southern (C. p. dorsalis), and western (C. p. bellii).[118]
Originally described in 1783 by Johann Gottlob Schneider as Testudo picta,[5][122] the painted turtle was called Chrysemys picta first by John Edward Gray in 1855. The four subspecies were then recognized: the eastern by Schneider in 1783,[122][123] the western by Gray in 1831,[123][124] and the midland and southern by Louis Agassiz in 1857.[125][126]
Until the 1930s many of the subspecies of the painted turtle were labeled by biologists as full species within Chrysemys, but this varied by the researcher. The painted turtles in the border region between the western and midland subspecies were sometimes considered a full species, treleasei. In 1931, Bishop and Schmidt defined the current "four in one" taxonomy of species and subspecies. Based on comparative measurements of turtles from throughout the range, they subordinated species to subspecies and eliminated treleasei.[127]
https://en.wikipedia.org/wiki/Four-toed_salamander
The four-toed salamander (Hemidactylium scutatum) is a lungless salamander native to eastern North America. It is a species of the monotypic genus Hemidactylium. (In Francophone Canada, it is called the salamandre à quatre orteils.)
FOUR SPECIES
https://en.wikipedia.org/wiki/Neurergus
Generally, Neurergus species are dark-colored (brown to black) above, with a pattern of white to yellow to orange spots and lines. On their ventral sides, the lighter color of their spots becomes a solid color. Like most salamanders, they have five toes on their hind feet.
Species[edit]
Studies have demonstrated the genus Neurergus is monophyletic.[2] It contains these species:
Yellow-spotted newt, N. crocatus (Cope, 1862)
Kaiser's spotted newt, N. kaiseri (Schmidt, 1952)
Kurdistan spotted newt, N. microspilotus (Nesterov, 1916)
Strauch's spotted newt, N. strauchii (Steindachner, 1887)
FOUR GENERA
https://en.wikipedia.org/wiki/Kinosternidae
The Kinosternidae are a family of mostly small turtles that includes the mud turtles and musk turtles. The family contains 25 species within four genera
Kinosternids lay about four hard-shelled eggs during the late spring and early summer
FOUR SPECIES
https://en.wikipedia.org/wiki/Box_turtle
Currently four species are classified within the genus and twelve taxa are distinguished:[1]
Terrapene carolina carolina (young)
Common box turtle, Terrapene carolina (Linnaeus, 1758) (type species)[2]
Florida box turtle, Terrapene carolina bauri Taylor, 1895
Eastern box turtle, Terrapene carolina carolina (Linnaeus, 1758)
Gulf Coast box turtle, Terrapene carolina major (Agassiz, 1857)
Mexican box turtle, Terrapene carolina mexicana (Gray, 1849)
Terrapene carolina putnami O.P. Hay, 1906 (extinct) [4]
Three-toed box turtle, Terrapene carolina triunguis (Agassiz, 1857)
Yucatán box turtle, Terrapene carolina yucatana (Boulenger, 1895)
Coahuilan box turtle, Terrapene coahuila Schmidt & Owens, 1944
Spotted box turtle, Terrapene nelsoni Stejneger, 1925
Northern spotted box turtle, Terrapene nelsoni klauberi Bogert, 1943
Southern spotted box turtle, Terrapene nelsoni nelsoni Stejneger, 1925
Ornate box turtle (or: Western box turtle), Terrapene ornata, (Agassiz, 1857)
Ornate box turtle (or: Western box turtle), Terrapene ornata ornata (Agassiz, 1857)
Desert box turtle, Terrapene ornata luteola H.M
FOUR SPECIES
https://en.wikipedia.org/wiki/Pangshura
Pangshura is a genus of geoemydid turtles endemic to South Asia. Its member species were formerly in the obsolete genus Kachuga.[1] A fifth member, Pangshura tatrotia, was described in 2010, but it is only known from Pliocene fossils.[2]
Species[edit]
The described species are:
Pangshura smithii - brown roofed turtle
Pangshura sylhetensis - Assam roofed turtle[3]
Pangshura tecta - Indian roofed turtle
Pangshura tentoria - Indian tent turtle
FOURTH ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Clemmys
Clemmys is a genus of turtle, consisting of one North American species, the spotted turtle (C. guttata).
"Clemmys guangxiensis" is a composite taxon described from specimens of Mauremys mutica and the natural hybrid "Mauremys" × iversoni.[1]
Until recently, the genus Clemmys consisted of four species (bog turtle, spotted turtle, western pond turtle, and the wood turtle). Recent genetic analyses have revealed that the spotted turtle is distinct from the other three species.
KNOWN FROM FOUR STREAMS
https://en.wikipedia.org/wiki/Kaiser%27s_spotted_newt
Kaiser's spotted newt (Neurergus kaiseri), also known as the Luristan newt or emperor spotted Newt (not to be confused with Tylototriton shanjing), is a species of very colourful salamander in the Salamandridae family. It is endemic to the southern Zagros Mountains in Iran where it is known from just four streams. Populations of this newt have been declining and the International Union for Conservation of Nature has rated it as "vulnerable". A captive breeding programme has been established in several zoos.
FOUR SPECIES
https://en.wikipedia.org/wiki/Thaumatogryllus
Thaumatogryllus is a genus of crickets in the family Gryllidae. It currently consists of four species, all of which are endemic to Hawaiʻi. Though very little is known about any of these species, it can be confirmed that T. conantae shows obvious signs of island gigantism. The other three species, especially T. cavicola, may also be affected by this phenomenon.
Species[edit]
Thaumatogryllus cavicola - volcanoes cave cricket (island of Hawaiʻi)
This cricket spends its entire life on the ceiling of lava tubes. If it were to descend to the floor, it would quickly be eaten by hunting spiders. It likes to eat roots that hang from the ceiling.[citation needed]
Thaumatogryllus conanti D. Otte, 1994 - Conant's giant Nihoa tree cricket (Nihoa)
Thaumatogryllus mauiensis - (Maui)
Thaumatogryllus variegatus - Kauaʻi thin-footed bush cricket (Kauaʻi)
FOUR SUBFAMILIES OF MAJORITY OF SALAMANDERS
https://en.wikipedia.org/wiki/Lungless_salamander
The family Plethodontidae consists of four subfamilies and about 380 species divided among these genera, making up the majority of known salamander species:[4]
FOUR SPECIES
https://en.wikipedia.org/wiki/Taricha
The genus Taricha consists of four species of newts in the family Salamandridae.[1][2] Their common name is Pacific newts, sometimes also western newts[3] or roughskin newts. The four species within this genus are the California newt, the rough-skinned newt, the red-bellied newt, and the sierra newt, all of which are found on the Pacific coastal region from southern Alaska to southern California, with one species possibly ranging into northern Baja California, Mexico.[1]
Contents [hide]
1 Species
2 Differentiating between species
3 Behavior
4 Toxicity
5 References
Species[edit]
Genus Taricha contains the following species:[1][2]
Taricha granulosa (Skilton, 1849) — Rough-skinned newt
Taricha rivularis (Twitty, 1935) — Red-bellied newt
Taricha sierrae (Twitty, 1942) — Sierra newt
Taricha torosa (Rathke, 1833) — California newt
FOUR GENERA
https://en.wikipedia.org/wiki/Rhinoceros
The family Rhinocerotidae consists of only four extant genera: Ceratotherium (White rhinoceros), Dicerorhinus (Sumatran rhinoceros), Diceros (Black rhinoceros) and Rhinoceros (Indian and Javan rhinoceros)
FOUR SUBSPECIES BLACK RHINO
https://en.wikipedia.org/wiki/Rhinoceros
There are four subspecies of black rhino: South-central (Diceros bicornis minor), the most numerous, which once ranged from central Tanzania south through Zambia, Zimbabwe and Mozambique to northern and eastern South Africa; South-western (Diceros bicornis occidentalis) which are better adapted to the arid and semi-arid savannas of Namibia, southern Angola, western Botswana and western South Africa; East African (Diceros bicornis michaeli), primarily in Tanzania; and West African (Diceros bicornis longipes) which was declared extinct in November 2011.[12] The native Tswanan name keitloa describes a South African variation of the black rhino in which the posterior horn is equal to or longer than the anterior horn.[13]
FOUR PLATIN AMERICAN TAPIR
https://en.wikipedia.org/wiki/Baird%27s_tapir
Baird's tapir (Tapirus bairdii), also known as the Central American tapir, is a species of tapir native to Mexico, Central America and northwestern South America.[2] It is one of four Latin American species of tapir.
FOUR CLOVERS
https://en.wikipedia.org/wiki/Marsilea
Marsilea is a genus of approximately 65 species of aquatic ferns of the family Marsileaceae. The name honours Italian naturalist Luigi Ferdinando Marsigli (1656–1730).[3]
These small plants are of unusual appearance and do not resemble common ferns. Common names include water clover and four-leaf clover because the long-stalked leaves have four clover-like lobes and are either held above water or submerged.
FOUR SPECIES
https://en.wikipedia.org/wiki/Anteater
Anteater is a common name for the four extant mammal species of the suborder Vermilingua[1] (meaning "worm tongue") commonly known for eating ants and termites.
The four extant species of anteaters
Giant anteater
Silky anteater
Southern tamandua
Northern tamandua
SINCE HAVE FOUR IDENTICAL OFFSPRING- SCIENTISTS STUDY THE DASYPUS
https://en.wikipedia.org/wiki/Armadillo
Most members of the genus Dasypus give birth to four monozygotic young (that is, identical quadruplets)
The nine-banded armadillo also serves science through its unusual reproductive system, in which four genetically identical offspring are born, the result of one original egg.[20][21][22] Because they are always genetically identical, the group of four young provides a good subject for scientific, behavioral, or medical tests that need consistent biological and genetic makeup in the test subjects. This is the only reliable manifestation of polyembryony in the class Mammalia, and exists only within the genus Dasypus and not in all armadillos, as is commonly believed. Other species that display this trait include parasitoid wasps, certain flatworms, and various aquatic invertebrates.[21]
USED FOR STUDIES IN SCIENCE BECAUSE HAVE FOUR IDENTICAL OFFSPRING- THE DROSOPHILIA IS USED IN SCIENCE BECAUSE HAS FOUR PARTS OF CHROMOSOME- MODEL ORGANISM
https://en.wikipedia.org/wiki/Nine-banded_armadillo
Mating takes place during a two-to-three month long mating season, which occurs from July–August in the Northern Hemisphere and November–January in the Southern Hemisphere. A single egg is fertilized, but implantation is delayed for three to four months to ensure the youngwill not be born during an unfavorable time. Once the zygote does implant in the uterus, a gestation period of four months occurs, during which the zygote splits into four identical embryos, each of which develops its own placenta, so blood and nutrients are not mixed between them. They are born in March and weighs 85 oz (85 g).[21] After birth, the quadruplets remain in the burrow, living off the mother’s milk for about three months. They then begin to forage with the mother, eventually leaving after six months to a year.[6][17]
https://en.wikipedia.org/wiki/Llanos_long-nosed_armadillo
The litter size is usually four. As is the case with other members of Dasypus,[4] all the embryos develop from a single zygote, making them identical quadruplets.[5
FOUR SPECIES
Cabassous is a genus of South and Central American armadillos.[1] The name is the Latinised form of the Kalini word for "armadillo".[2]
https://en.wikipedia.org/wiki/Cabassous
The genus contains the following four species:[3]
Northern naked-tailed armadillo, C. centralis
Chacoan naked-tailed armadillo, C. chacoensis
Greater naked-tailed armadillo, C. tatouay
Southern naked-tailed armadillo, C. unicinctus
https://en.wikipedia.org/wiki/Balaenidae
Based on morphology and molecular data, four extant family-level clades are recognized within Mysticeti: Balaenidae (bowhead and right whales), Neobalaenidae (pygmy right whales), Eschirichtiidae (gray whales), and Balaenopteridae (rorquals).[
https://en.wikipedia.org/wiki/Balaenidae
The four species of the Balaenidae that are found throughout temperate and polar waters; Eubalaena glacialis (North Atlantic right whale), Eubalaena japonica (North Pacific right whale), Eubalaena australis (Southern right whale), and Balaena mysticetus (Bowhead whale). Bowhead and right whales can reach up to 18 meters in length and over 100 tons at maturity.[9][10]
https://en.wikipedia.org/wiki/Baleen_whale
Baleen whales are cetaceans classified under the parvorder Mysticeti, and consist of four extant families: Balaenidae (right whales), Balaenopteridae (rorquals), Cetotheriidae (pygmy right whale), and Eschrichtiidae (gray whale).
https://en.wikipedia.org/wiki/Balaenoptera
†Balaenoptera colcloughi[edit]
B. colcloughi is known from four specimens, including four skulls and some postcranial remains, found at the San Diego Formation. It was a close relative of Megaptera novaeangliae (the humpback whale), B. siberi, and B. physalus (the fin whale).[7]
FOUR SPECIES
https://en.wikipedia.org/wiki/Crossarchus
Species[edit]
Alexander's kusimanse, Crossarchus alexandri
Angolan kusimanse, Crossarchus ansorgei
Common kusimanse, Crossarchus obscurus
Flat-headed kusimanse, Crossarchus platycephalus
https://en.wikipedia.org/wiki/Four-toed_rice_tenrec
The four-toed rice tenrec (Oryzorictes tetradactylus) is a species of mammal in the family Tenrecidae. It is endemic to Madagascar. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests, subtropical or tropical high-altitude shrubland, subtropical or tropical high-altitude grassland, and swamps.[2]
FOUR SPECIES
https://en.wikipedia.org/wiki/Hyrax
Four extant species are recognised; the rock hyrax (Procavia capensis), the yellow-spotted rock hyrax (Heterohyrax brucei), the western tree hyrax (Dendrohyrax dorsalis) and the southern tree hyrax (D. arboreus). Their distribution is limited to Africa and the Middle East.
In the 2000s, taxonomists reduced the number of recognized species of hyrax. In 1995, 11 or more species were recognized; in 2013, only four are recognized, with the others now each considered as a subspecies of one of the recognized four. Over 50 subspecies and species are described, many of which are considered highly endangered.[24]
TRUNK - https://en.wikipedia.org/wiki/Asian_elephant
Four basic muscle masses—the radial, the longitudinal and two oblique layers—and the size and attachments points of the tendon masses allow the shortening, extension, bending, and twisting movements accounting for the ability to hold, and manipulate loads of up to 300 kg (660 lb)
https://en.wikipedia.org/wiki/Gomphothere
Gomphotheres differed from elephants in their tooth structure, particularly the chewing surfaces on the molar teeth. Most had four tusks, and their retracted facial and nasal bones prompt paleontologists to believe that gomphotheres had elephant-like trunks.[6]
Tetralophodon ("four-ridged tooth") is an extinct gomphothere genus belonging to the family Gomphotheriidae.[1][2][3]
https://en.wikipedia.org/wiki/Tetralophodon
Contents [hide]
1 Etymology
2 Description
3 Distribution
4 See also
5 References
Etymology[edit]
The genus Tetralophodon (meaning "four-ridged tooth") was named in the mid-19th century with the discovery of the specialized teeth.
Description[edit]
Fossil jaws of T. longirostris, at the Naturhistorisches Museum, Vienna
Tetralophodon was an elephant-like animal which existed through the late Miocene to the Middle Pleistocene epochs,[4] approximately 10.9 million years.
Like typical gomphotheres, mastodons with four tusks, Tetralophodon had four tusks and a trunk. In fact, also this animal had two further tusks protruding from the jaw. The overall appearance recalled Gomphotherium, the best known genus of the family Gomphotheriidae.
Their body is believed to be about 2.58–3.45 m (8.5–11.3 ft) tall at the shoulder and up to 10 tonnes in weight,[5] larger than the size of the present Asian elephant, with the long trunk and incisors ranging up to 2 m (6.6 ft) long. These incisors are believed to be utilized as a defense mechanism
The large, four-cusped cheek teeth of these animals are approximately 60 mm (2.4 in) by 80 mm (3.1 in), about 6 times the size of a normal human tooth. These low-crowned, bunodont teeth are designed for crushing and grinding, compared with other mammals during this era that had sharp teeth used for cutting. The teeth of the tetralophodon indicate a diet of large fruits and vegetables. This diet is aided by the large size and long trunks of the elephantiods that enable these mammals to reach tall, fruit-bearing trees.
https://en.wikipedia.org/wiki/Paratetralophodon
TETRA IS FOUR
Paratetralophodon is an extinct genus of gomphothere. Paratetralophodon may be an ancestor of Tetralophodon. The elephant-like animal lived through the Miocene and Pliocene epochs. It had four tusks and a trunk.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Stegotetrabelodontinae
Stegotetrabelodontinae is an extinct subfamily of large herbivorous mammals that were closely related to elephants.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Stegotetrabelodon
Stegotetrabelodon is an extinct genus of primitive elephant with gomphothere-like anatomical features from the Late Miocene to Early Pliocene of Africa and Eurasia
https://en.wikipedia.org/wiki/Obdurodon
Obdurodon is an extinct monotreme genus containing four species
FOUR LIVING SPECIES
https://en.wikipedia.org/wiki/Mergus
Species[edit]
†New Zealand merganser, Mergus australis (extinct, c.1902)
Common merganser or goosander, Mergus merganser
Brazilian merganser, Mergus octosetaceus
Red-breasted merganser, Mergus serrator
Scaly-sided merganser, Mergus squamatus
https://en.wikipedia.org/wiki/Brazilian_merganser
The Brazilian mergansers are generally silent birds, but may make barking calls in certain situations. Four calls have been recorded. A harsh krack-krack acts as an alarm call emitted in flight. Males make a barking dog-like call, females make a harsh rrr-rrrr and the contact call ia a soft rak-rak-rak. Ducklings give a high pitched ik-ik-ik.
https://en.wikipedia.org/wiki/Steamer_duck
FOUR SPECIES
The steamer ducks are a genus (Tachyeres) of ducks in the family Anatidae. All of the four species occur at the southern cone of South America in Chile and Argentina, and all except the flying steamer duck are flightless; even this one species capable of flight rarely takes to the air
There are four species:[2]
Flying steamer duck (Tachyeres patachonicus)
Fuegian steamer duck (Tachyeres pteneres)
Chubut steamer duck (Tachyeres leucocephalus)
Falkland steamer duck (Tachyeres brachypterus)
https://en.wikipedia.org/wiki/Evolution_of_birds
Four distinct lineages of bird survived the Cretaceous-Tertiary extinction event 66 million years ago, giving rise to ostriches and relatives (Paleognathae), ducks and relatives (Anseriformes), ground-living fowl (Galliformes), and “modern birds” (Neoaves).
https://en.wikipedia.org/wiki/Ostariophysi
The division of the Otophysi into the four extant clades closely follows the breakup of Pangea
The four largest families in this group (Cyprinidae, Characidae, Loricariidae, and Balitoridae) include 4,656 species, over half (59%) of ostariophysian species.
https://en.wikipedia.org/wiki/Channel_catfish
FOUR PAIRS BARBELS
In addition, the channel catfish has taste buds distributed over the surface of its entire body.[citation needed] These buds are especially concentrated on the fish's four pair of barbels (whiskers) surrounding the mouth
TETRA IS FOUR- FOUR CLADES
https://en.wikipedia.org/wiki/Tetraodontidae
The Tetraodontidae are a family of primarily marine and estuarine fish of the order Tetraodontiformes
The scientific name refers to the four large teeth, fused into an upper and lower plate, which are used for crushing the shells of crustaceans and mollusks, their natural prey.
The tetraodontids have been estimated to diverge from diodontids between 89 and 138 million years ago. The four major clades diverged during the Cretaceous between 80 and 101 million years ago.
FOUR FAMILIES
https://en.wikipedia.org/wiki/Electric_ray
The electric rays are a group of rays, flattened cartilaginous fish with enlarged pectoral fins, comprising the order Torpediniformes. They are known for being capable of producing an electric discharge, ranging from 8 to 220 volts, depending on species, used to stun prey and for defense.[2] There are 69 species in four families.
FOUR CENTRAL NERVES
The organs are governed by four central nerves from each side of the electric lobe, or specialized brain lobe, which is of a different color from the rest of the brain
Family Narcinidae (numbfishes)
Subfamily Narcininae
Genus Benthobatis
Genus Diplobatis
Genus Discopyge
Genus Narcine
Subfamily Narkinae (sleeper rays)
Genus Crassinarke
Genus Electrolux
Genus Heteronarce
Genus Narke
Genus Temera
Genus Typhlonarke
Family Torpedinidae (torpedo electric rays)
Subfamily Hypninae (coffin rays)
Genus Hypnos
Subfamily Torpedininae
Genus Tetronarce
Genus Torpedo
https://en.wikipedia.org/wiki/Lycopodiopsida
Starting from the four genera accepted by Øllgaard,[2] a study based on chloroplast DNA produced the cladogram shown below (reproduced here to genus level only),[3] confirming the monophyly of the four genera, and their distance from Isoetes.
THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Macrocystis
Initially, 17 species were described within the genus Macrocystis.[11] In 1874, Hooker, following blade morphology, put them all under the same taxon, Macrocystis pyrifera.[12] Then came the current classification, based on the holdfast morphology, which distinguished three species. A fourth one was described in 1986, based on the blade morphology.[13] Here are the four currently accepted species of Macrocystis.[14]
Macrocystis angustifolia Bory de Saint-Vincent, with mounding rhizomatus holdfast ;
Macrocystis integrifolia Bory de Saint-Vincent, also known as "great kelp", with a rhizomatous holdfast, much smaller, the sporangial thalli growing only to 6 m long;
Macrocystis laevis C. H. Hay, with a conical holdfast and smooth fleshy blades;
Macrocystis pyrifera (L.) C. Ag., also known as "giant kelp" or "giant bladder kelp", with a conical holdfast. It can grow over 45 metres long and can do so in one growing season, making it the organism with the world's fastest linear growth.[4]
However, this classification may also be revised since three of the four Macrocystis species are interfertile [15][16](M. laevis ' interfertility has not yet been tested[7]), holdfast as well as blade morphology is plastic,[17] and all four species are genetically similar.[18]
Recent genetic research increasingly favors the grouping of all Macrocystis species into one: Macrocystis pyrifera. [19]
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https://en.wikipedia.org/wiki/Flexor_digitorum_superficialis_muscle
Four long tendons come off this muscle near the wrist and travel through the carpal tunnel formed by the flexor retinaculum. These tendons, along with those of flexor digitorum profundus, are enclosed by a common flexor sheath. The tendons attach to the anterior margins on the bases of the intermediate phalanges of the four fingers. These tendons have a split (Camper's Chiasm) at the end of them through which the tendons of flexor digitorum profundus pass.
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FOUR TENDONS
https://en.wikipedia.org/wiki/Flexor_digitorum_brevis_muscle
It arises by a narrow tendon, from the medial process of the tuberosity of the calcaneus, from the central part of the plantar aponeurosis, and from the intermuscular septa between it and the adjacent muscles.
It passes forward, and divides into four tendons, one for each of the four lesser toes.
CHLOROPHYL IS A TETRAPYROLE- TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetrapyrrole
Tetrapyrroles are a class of chemical compounds whose molecules contain four pyrrole rings held together by direct covalent bonds or by one-carbon bridges (=(CH)- or -CH
2- units), in either a linear or a cyclic fashion. A pyrrole ring in a molecule is a five-atom ring where four of the ring atoms are carbon and one is nitrogen. In cyclic tetrapyrroles, lone electron pairs on nitrogen atoms facing the center of the macrocycle ring can bond or chelate with a metal ion such as iron, cobalt, or magnesium.
Some tetrapyrroles are the active cores of some compounds with crucial biochemical roles in living systems, such as hemoglobin and chlorophyll. In these two molecules, in particular, the pyrrole macrocycle ring frames a metal atom, that forms a coordination compound with the pyrroles and plays a central role in the biochemical function of those molecules.
Structure[edit]
Linear tetrapyrroles (called bilanes) include:[1]
Heme breakdown products (e.g., bilirubin, biliverdin)
Phycobilins (found in cyanobacteria)
Luciferins as found in dinoflagellates and euphausiid shrimps (krill)
Bilirubin ZZ.png Biliverdin3.svg Phycoerythrobilin.svg Luciferin dinoflagellate.svg
Bilirubin Biliverdin Phycoerythrobilin Dinoflagellate (R = H) and
krill (R = OH) luciferin
Cyclic tetrapyrroles having four one-carbon bridges include:[2]
Porphin, the simplest tetrapyrrole
Porphyrins, including heme, the core of hemoglobin
Chlorins, including those at the core of chlorophyll.
Cyclic tetrapyrroles having three one-carbon bridges and one direct bond between the pyrroles include:
Corrins, including the cores of cobalamins, when complexed with a cobalt ion.
Heme group of hemoglobin C-3 position Chlorophyll a.svg Cobalamin.svg
Heme group of hemoglobin
with a porphin macrocycle. The chlorin section of the chlorophyll a molecule.
The green box shows a group that varies between chlorophyll types. Cobalamin structure includes a corrin macrocycle.
The tetrapyrrole portions of the molecules typically act as chromophores because of a high degree of conjugation in them. Therefore, these compounds are commonly colored.
https://en.wikipedia.org/wiki/Beta_barrel
Jelly roll[edit]
The jelly roll barrel, also known as the Swiss roll, is a complex nonlocal structure in which four pairs of antiparallel beta sheets, only one of which is adjacent in sequence, are "wrapped" in three dimensions to form a barrel shape.
FOUR MATRICES
https://en.wikipedia.org/wiki/GOR_method
The GOR method analyzes sequences to predict alpha helix, beta sheet, turn, or random coil secondary structure at each position based on 17-amino-acid sequence windows. The original description of the method included four scoring matrices of size 17×20, where the columns correspond to the log-odds score, which reflects the probability of finding a given amino acid at each position in the 17-residue sequence. The four matrices reflect the probabilities of the central, ninth amino acid being in a helical, sheet, turn, or coil conformation. In subsequent revisions to the method, the turn matrix was eliminated due to the high variability of sequences in turn regions (particularly over such a large window). The method was considered as best requiring at least four contiguous residues to score as alpha helices to classify the region as helical, and at least two contiguous residues for a beta sheet.[3]
FOUR ORGANS FLOWER- I DESCRIBED TREES HAVE FOUR PARTS TOO- ALL FLOWERS HAVE FOUR BASIC ORGANS
https://en.wikipedia.org/wiki/Arabidopsis_thaliana
A. thaliana has been extensively studied as a model for flower development. The developing flower has four basic organs: sepals, petals, stamens, and carpels (which go on to form pistils). These organs are arranged in a series of whorls: four sepals on the outer whorl, followed by four petals inside this, six stamens, and a central carpel region. Homeotic mutations in A. thaliana result in the change of one organ to another — in the case of the agamous mutation, for example, stamens become petals and carpels are replaced with a new flower, resulting in a recursively repeated sepal-petal-petal pattern.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetrablemmidae
The Tetrablemmidae are a spider family with 126 described species in 29 genera that occur throughout the world tropics. They are sometimes called armored spiders.
FOUR CLASSES OF TETRAPOD
https://en.wikipedia.org/wiki/Tetrapod
The classification of tetrapods has a long history. Traditionally, tetrapods are divided into four classes based on gross anatomical and physiological traits.[45] Snakes and other legless reptiles are considered tetrapods because they are sufficiently like other reptiles that have a full complement of limbs. Similar considerations apply to caecilians and aquatic mammals. Newer taxonomy is frequently based on cladistics instead, giving a variable number of major "branches" (clades) of the tetrapod family tree.
The tetrapods, including all large- and medium-sized land animals, have been among the best understood animals since earliest times. By Aristotle's time, the basic division between mammals, birds and egg-laying tetrapods (the "herptiles") was well known, and the inclusion of the legless snakes into this group was likewise recognized.[46] With the birth of modern biological classification in the 18th century, Linnaeus used the same division, with the tetrapods occupying the first three of his six classes of animals.[47] While reptiles and amphibians can be quite similar externally, the French zoologist Pierre André Latreille recognized the large physiological differences at the beginning of the 19th century and split the herptiles into two classes, giving the four familiar classes of tetrapods: amphibians, reptiles, birds and mammals.[48]
Four cone opsins were present in the first vertebrate, inherited from invertebrate ancestors:
LWS/MWS (long- to medium-wave sensitive) - green, yellow, or red
SWS1 (short-wave sensitive) - ultraviolet or violet - lost in monotremes (platypus, echidna)
SWS2 (short-wave sensitive) - violet or blue - lost in therians (placental mammals and marsupials)
RH2 (rhodopsin-like cone opsin) - green - lost separately in amphibians and mammals, retained in reptiles and birds
https://en.wikipedia.org/wiki/Anseriformes
Studies of the mitochnodrial DNA suggest the existence of four branches – Anseranatidae, Dendrocygninae, Anserinae and Anatinae – with Dendrocygninae being a subfamily within the family Anatidae and Anseranatidae representing an independent family.[10] The clade Somaterini has a single genus Somateria.
https://en.wikipedia.org/wiki/Catfish
Catfish may have up to four pairs of barbels: nasal, maxillary (on each side of mouth), and two pairs of chin barbels, even though pairs of barbels may be absent depending on the species.
https://en.wikipedia.org/wiki/Neolamprologus_pulcher
Their colors tend to be brown, yellow, blue, black or a combination or all four
TETRA IS FOUR
This is alluded to in their name, derived from the Greek words tetra meaning "four" and odous meaning "tooth" and the Latin forma meaning "shape". Counting these teeth-like bones is a way of distinguishing similar families, for example, the Tetraodontidae ("four-toothed"), Triodontidae ("three-toothed"), and Diodontidae ("two-toothed").
https://en.wikipedia.org/wiki/Tetraodontiformes
The Tetraodontiformes are an order of highly derived ray-finned fish, also called the Plectognathi.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetraodon
Tetraodon is a genus in the pufferfish family (Tetraodontidae) found in freshwater in Africa
FOUR ORDERS
https://en.wikipedia.org/wiki/Batoidea
Nelson's 2006 Fishes of the World recognizes four orders.
https://en.wikipedia.org/wiki/Batoidea
Order Torpediniformes[edit]
Main article: Electric ray
Family Hypnidae (coffin rays)
Family Narcinidae (numbfishes)
Family Narkidae (sleeper rays)
Family Torpedinidae (torpedo rays)
Order Rhinopristiformes[edit]
Main article: Rhinopristiformes
Family Glaucostegidae (giant guitarfishes)
Family Platyrhinidae* (fanrays)
Family Pristidae (sawfishes)
Family Rhinidae (wedgefishes)
Family Rhinobatidae (guitarfishes)
Family Trygonorrhinidae (banjo rays)
Family Zanobatidae* (panrays)
* the placement of these families is uncertain
Order Rajiformes[edit]
Main article: Rajiformes
Family Anacanthobatidae (legskates)
Family Arhynchobatidae (softnose skates)
Family Gurgesiellidae (pygmy skates)
Family Rajidae (skates)
Order Myliobatiformes[edit]
Main article: Myliobatiformes
Family Aetobatidae (pelagic eagle rays)
Family Dasyatidae (whiptail stingrays)
Family Gymnuridae (butterfly rays)
Family Hexatrygonidae (sixgill stingrays)
Family Myliobatidae (devilrays)
Family Plesiobatidae (giant stingarees)
Family Potamotrygonidae (Neotropical stingrays)
Family Rhinopteridae (cownose rays)
Family Urolophidae (stingarees)
Family Urotrygonidae (round stingrays)
FOUR GENERA
https://en.wikipedia.org/wiki/Narcinidae
These genera are included in this family:[5]
Benthobatis
Diplobatis
Discopyge
Narcine
FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Klebsormidiaceae
The Klebsormidiaceae are a family containing three genera of charophyte green alga forming multicellular, non-branching filaments.[2][3] A fourth genus Chlorokybus is sometimes included as well,[4] but this problematic and poorly known genus is sometimes placed in a separate class Chlorokybophyceae.
FOUR GENERA
https://en.wikipedia.org/wiki/Dipodascaceae
The Dipodascaceae are a family of yeasts in the order Saccharomycetales. According to the 2007 Outline of Ascomycota, the family contains four genera; however, the placement of Sporopachydermia and Yarrowia is uncertain.[1] Species in the family have a widespread distribution, and are found in decaying plant tissue, or as spoilage organisms in the food industry.[2]
https://en.wikipedia.org/wiki/Genetic_studies_on_Jews
A 2006 study by Behar et al.,[62] based on high-resolution analysis of Haplogroup K (mtDNA), suggested that about 40% of the current Ashkenazi population is descended matrilineally from just four women, or "founder lineages", of European origin and some "may" have mixture of a Hebrew/Levantine mtDNA pool originating in the Middle East in the 1st and 2nd centuries CE. Moreover, a maternal line "sister" was found among the Jews of Portugal, North Africa, France, and Italy. They wrote:
Both the extent and location of the maternal ancestral deme from which the Ashkenazi Jewry arose remain obscure. Here, using complete sequences of the maternally inherited mitochondrial DNA (mtDNA), we show that close to one-half of Ashkenazi Jews, estimated at 8,000,000 people, can be traced back to only four women carrying distinct mtDNAs that are virtually absent in other populations, with the important exception of low frequencies among non-Ashkenazi Jews. We conclude that four founding mtDNAs, likely of Near Eastern ancestry, underwent major expansion(s) in Europe within the past millennium...[19][62]
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https://en.wikipedia.org/wiki/Lakshmi_Tatma
Lakshmi Tatma (Hindi: लक्ष्मी तात्मा) is an Indian girl born in 2005 in a village in Araria district, Bihar, having "four arms and four legs." She was actually one of a pair of ischiopagus conjoined twins one of which was headless because its head had atrophied and chest had not fully developed in the womb, causing the appearance of one child with four arms and four legs.
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https://en.wikipedia.org/wiki/Japanese_sleeper_ray
The first specimens of the Japanese sleeper ray known to science were four fish collected from Japan by German naturalists Philipp Franz von Siebold and Heinrich Burger during the second quarter of the 19th century. The specimens were stuffed and deposited at the National Museum of Natural History in Leiden; three of them were labeled as "Narcine spec." and one as "Narcine timlei".[2] This material formed the basis for a description authored by Coenraad Jacob Temminck and Hermann Schlegel, which was published in 1850 as part of Fauna Japonica, a series of monographs on Japanese zoology.[3] Temminck and Schlegel assigned the new species to the subgenus Astrape of the genus Torpedo; later authors would synonymize Astrape with Narke.[4] In 1947, Marinus Boeseman reexamined the four original specimens and designated the largest, 27 cm (11 in) long, as the species lectotype.[2] Other common names for this ray are Japanese electric ray and Japanese spotted torpedo.[5] Some taxonomists believe that the sleeper torpedo (Crassinarke dormitor) may be conspecific with the Japanese sleeper ray, as their morphology is virtually identical.[6]
FOUR SUPERORDERS FOUR SUBORDERS
https://en.wikipedia.org/wiki/Hemiptera
The order is now divided into four or more suborders, after the "Homoptera" were established as paraphyletic (now the Auchenorrhyncha and the Sternorrhyncha)
DENTATE GYRUS HAVE FOUR LAYERS- FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Hippocampus
The dentate gyrus has three layers of cells (or four if the hilus is included). The layers are from the outer in - the molecular layer, the inner molecular layer, the granular layer, and the hilus. The CA3 in the hippocampus proper has the following cell layers known as strata: lacunosum-moleculare, radiatum, lucidum, pyramidal, and oriens. CA2 and CA1 also have four each of these layers and not the lucidum stratum.
https://en.wikipedia.org/wiki/Malacoraja
Malacoraja, or soft skates, is a small genus of skates in the family Rajidae found at depths of 46–1,568 m (151–5,144 ft) in the Atlantic.[1] It currently consists of four described species,[1] as well as a possible undescribed species.[2]
Species[edit]
Malacoraja kreffti (Stehmann, 1978) (Krefft's skate)
Malacoraja obscura M. R. de Carvalho, U. L. Gomes & Gadig, 2005 (Brazilian soft skate)
Malacoraja senta (Garman, 1885) (Smooth skate)
Malacoraja spinacidermis (Barnard, 1923) (Soft skate)
https://en.wikipedia.org/wiki/Albacore
The albacore is one of the main four species of tuna that support oceanic fisheries along with the skipjack, yellowfin, and the bigeye tunas
https://www.worldwildlife.org/species/tuna
The majority of the market is made up of four species: skipjack, yellowfin, bigeye and albacore
FOUR SPECIES SCOMBER
https://en.wikipedia.org/wiki/Rastrelliger
https://en.wikipedia.org/wiki/Scombrini
Scomber Linnaeus, 1758
Scomber australasicus Cuvier, 1832, Blue mackerel
Scomber colias Gmelin, 1789, Atlantic chub mackerel
Scomber japonicus, Houttuyn, 1782, Chub mackerel
Scomber scombrus Linnaeus, 1758, Atlantic mackerel
FOUR GENERA
https://en.wikipedia.org/wiki/Bonito
Bonitos are a tribe of medium-sized, ray-finned predatory fish in the family Scombridae – a family it shares with the mackerel, tuna, and Spanish mackerel tribes, and also the butterfly kingfish.[1] Also called the Sardini tribe, it consists of eight species across four genera; three of those four genera are monotypic, having a single species each.
FOUR SPECIES
https://en.wikipedia.org/wiki/Diplobatis
Diplobatis is a genus of electric rays in the family Narcinidae.
Species[edit]
Diplobatis colombiensis Fechhelm & McEachran, 1984 (Colombian electric ray)
Diplobatis guamachensis Martín Salazar, 1957 (Brownband numbfish)
Diplobatis ommata (D. S. Jordan & C. H. Gilbert, 1890) (Ocellated electric ray)
Diplobatis pictus G. Palmer, 1950 (Painted electric ray)
FOUR SPECIES
https://en.wikipedia.org/wiki/Heteronarce
Heteronarce is a genus of sleeper rays in the family Narkidae. This genus is found only in the western Indian Ocean along the coasts of Africa, the Arabian Peninsula and India.
Species[edit]
There are currently four recognized species in this genus:[1]
Heteronarce bentuviai Baranes & J. E. Randall, 1989 (Elat electric ray)
Heteronarce garmani Regan, 1921 (Natal electric ray)
Heteronarce mollis Lloyd, 1907 (Soft electric ray)
Heteronarce prabhui Talwar, 1981 (Quilon electric ray)
FOUR SPECIES FOURTH DIFFERENT
https://en.wikipedia.org/wiki/Narke_(genus)
Narke is a genus of electric rays in the family Narkidae, found in the western Indo-Pacific and off southern Africa. They have nearly circular pectoral fin discs and short, thick tails with large caudal fins, and can be identified by their single dorsal fin (a trait shared only by Typhlonarke within the family). There are three described species, as well as a fourth undescribed dwarf species from Taiwan.[1]
https://en.wikipedia.org/wiki/Sympterygia
Sympterygia is a genus of fish in the family Rajidae found in oceans off South America.[1]
Species[edit]
There are four species in the genus:[1]
Sympterygia acuta Garman, 1877 (Bignose fanskate)
Sympterygia bonapartii J. P. Müller and Henle, 1841 (Smallnose fanskate)
Sympterygia brevicaudata Cope, 1877 (Shorttail fanskate)
Sympterygia lima Poeppig, 1835 (Filetail fanskate)
FOUR TRIBES
https://en.wikipedia.org/wiki/Scombrinae
The Scombrinae, therefore, comprise 50 extant species in 14 genera, grouped into four tribes:
Subfamily Scombrinae
Tribe Scombrini – mackerels
Genus Rastrelliger
Genus Scomber
Tribe Scomberomorini – Spanish mackerels
Genus Acanthocybium
Genus Grammatorcynus
Genus Orcynopsis
Genus Scomberomorus
Tribe Sardini – bonitos
Genus Sarda
Genus Cybiosarda
Genus Gymnosarda
Tribe Thunnini – tunas
Genus Allothunnus
Genus Auxis
Genus Euthynnus
Genus Katsuwonus
Genus Thunnus
FOUR FAMILIES/FOUR TRIBES
https://en.wikipedia.org/wiki/Scombridae
Jordan, Evermann and Clark (1930) divide these fishes into the four families: Cybiidae, Katsuwonidae, Scombridae, and Thunnidae,[4] but taxonomists later classified them all into a single family, the Scombridae.[5][6]
The 51 extant species are in 15 genera and two subfamilies – with the subfamily Scombrinae further grouped into four tribes, as:
Family Scombridae
Subfamily Gasterochismatinae
Genus Gasterochisma
Subfamily Scombrinae
Tribe Scombrini – mackerels
Genus Rastrelliger
Genus Scomber
Tribe Scomberomorini – Spanish mackerels
Genus Acanthocybium
Genus Grammatorcynus
Genus Orcynopsis
Genus Scomberomorus
Tribe Sardini – bonitos
Genus Sarda
Genus Cybiosarda
Genus Gymnosarda
Tribe Thunnini – tunas
Genus Allothunnus
Genus Auxis
Genus Euthynnus
Genus Katsuwonus
Genus Thunnus
FOUR LAYERS
https://en.wikipedia.org/wiki/Sole_(foot)
Intrinsic[edit]
First layer
Second layer
Third layer
Dorsal interossei
Plantar interossei
First, second, and third muscle layers, and the dorsal and plantar interossei
The intrinsic muscles in the sole are grouped in four layers:
In the first layer, the flexor digitorum brevis is the large central muscle located immediately below the plantar aponeurosis. It flexes the second to fifth toes and is flanked by abductor hallucis and abductor digiti minimi.[2]
In the second layer, the quadratus plantae, located below flexor digitorum brevis, inserts into the tendon of flexor digitorum longus on which the lumbricals originate.[2]
In the third layer, the oblique head of adductor hallucis joins the muscle's transversal head on the lateral side of the big toe. Medially to adductor hallucis are the two heads of flexor hallucis brevis, deep to the tendon of flexor hallucis longus. The considerably smaller flexor digiti minimi brevis on the lateral side can be mistaken for one of the interossei.[2]
In the fourth layer. the dorsal and plantar interossei are located between and below the metatarsal bones and act as antagonists.[2]
The central compartment is shared by the lumbricals, quadratus plantae, flexor digitorum brevis, and adductor hallucis; the medial compartment by abductor hallucis, flexor hallucis brevis, abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi (often considered part of the former muscle); whilst the lateral compartment is occupied by extensor digitorum brevis and extensor hallucis brevis. [3]
Swordfish is one of four fishes, along with tilefish, shark, and king mackerel
FOUR SPECIES
https://en.wikipedia.org/wiki/Sarda_(fish)
Sarda is a genus of medium-sized, predatory ray-finned bony fish in the Scombridae family, and belonging to the tribe Sardini, more commonly called the Bonito tribe. There are four species which comprise the Sarda genus. One of those species, the Pacific bonito, is further divided into two subspecies.
Species[edit]
Australian bonito, Sarda australis (Macleay, 1881).
Pacific Bonito, Sarda chiliensis (Cuvier, 1832).
Eastern Pacific bonito, Sarda chiliensis chiliensis (Cuvier, 1832).
Pacific bonito, Sarda chiliensis lineolata (Girard, 1858).
Striped bonito, Sarda orientalis (Temminck & Schlegel, 1844).
Atlantic bonito, Sarda sarda (Bloch, 1793).
64 IS FOUR 16S
https://en.wikipedia.org/wiki/Atlantic_Spanish_mackerel
Its single row of cutting edged teeth in each jaw (around sixty-four teeth in all) are large, uniform, closely spaced and flattened from side to side
https://en.wikipedia.org/wiki/Pacific_jack_mackerel
Recent genetic studies have divided the Carangidae into four subfamilies, with the genus Trachurus falling into the 'Caranginae' (or tribe Carangini), being most closely related to the 'scads' of the genera Decapterus and Selar.
https://en.wikipedia.org/wiki/Atlantic_bluefin_tuna
At that time, these fish were nicknamed shibi — "four days" — because chefs would bury them for four days to mellow their bloody taste.[10]
TETRA MEANS FOUR- FOUR SPECIES
https://en.wikipedia.org/wiki/Tetrapturus
Tetrapturus is a genus of marlins found in tropical and subtropical oceans throughout the world. Some are popular in big-game fishing.
Species[edit]
There are currently four recognized species in this genus:[1]
Tetrapturus angustirostris S. Tanaka (I), 1915 (Shortbill spearfish)
Tetrapturus belone Rafinesque, 1810 (Mediterranean spearfish)
Tetrapturus georgii R. T. Lowe, 1841 (Roundscale spearfish)
Tetrapturus pfluegeri C. R. Robins & de Sylva, 1963 (Longbill spearfish)
https://en.wikipedia.org/wiki/Nymphalidae
They are also called brush-footed butterflies or four-footed butterflies, because they are known to stand on only four legs while the other two are curled up
https://en.wikipedia.org/wiki/Four-spotted_chaser
The brown colour and the four spots on the wings make them unmistakable.
The four-spotted chaser (Libellula quadrimaculata), known in North America as the four-spotted skimmer, is a dragonfly of the family Libellulidae found frequently throughout Europe, Asia, and North America.
https://en.wikipedia.org/wiki/Lepidoptera
FOUR MOST SPECIOSE INSECTS
The Lepidoptera show many variations of the basic body structure that have evolved to gain advantages in lifestyle and distribution. Recent estimates suggest the order may have more species than earlier thought,[6] and is among the four most speciose orders, along with the Hymenoptera, Diptera, and Coleoptera.[4]
FOUR TEETH
https://en.wikipedia.org/wiki/Red_imported_fire_ant
Four larval instars have been described based on their morphological characters.[47][51] With the exception of size differences, the larvae of the minor and major workers are almost impossible to distinguish. Major worker 4th instar larvae tend to be larger than minor worker pre-pupae with a wider width. Only the reproductive larvae are larger than major workers and in general, are very robust. Even male third instar larvae tend to be longer and larger than third instar workers. No significant morphological difference can distinguish male and queen larvae, but the internal gonopodal imaginal discs differ. Most larval changes are not significant, but the moulting of 3rd instar larvae and studies of their eclosion support four larval instar stages.[47]
Polymorphism occurs in all species and the mandibles bear four teeth.
The anterior and superior cavity are formed by the bases of four malpighian tubules
The glandular system contains four glands: the mandibular, maxillary, labial and post-pharyngeal glands.
16 SQUARES QMR
https://en.wikipedia.org/wiki/Beta_barrelJelly roll[edit]The jelly roll barrel, also known as the Swiss roll, is a complex nonlocal structure in which four pairs of antiparallel beta sheets, only one of which is adjacent in sequence, are "wrapped" in three dimensions to form a barrel shape.
Sixteen- or eighteen-stranded beta barrel structures are common in porins, which function as transporters for ions and small molecules that cannot diffuse across a cellular membrane. Such structures appear in the outer membranes of gram-negative bacteria, chloroplasts, and mitochondria. The central pore of the protein, sometimes known as the eyelet, is lined with charged residues arranged so that the positive and negative charges appear on opposite sides of the pore. A long loop between two beta sheets partially occludes the central channel; the exact size and conformation of the loop helps in discriminating between molecules passing through the transporter.
https://en.wikipedia.org/wiki/GDNF_family_of_ligands
https://en.wikipedia.org/wiki/Enzyme-linked_receptor
The GDNF family of ligands (GFL) consists of four neurotrophic factors: glial cell line-derived neurotrophic factor (GDNF), neurturin (NRTN), artemin (ARTN), and persephin (PSPN). GFLs have been shown to play a role in a number of biological processes including cell survival, neurite outgrowth, cell differentiation and cell migration. In particular signalling by GDNF promotes the survival of dopaminergic neurons.[1]
FOUR SPECIES- FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Epiophlebia
The genus Epiophlebia is the sole member of the family Epiophlebiidae, which is itself the sole living representative of the Epiproctan infraorder Epiophlebioptera, and it contains only four species. The first two species were historically placed in their own suborder Anisozygoptera, considered intermediate between dragonflies and damselflies, mainly because the hind wings are very similar in size and shape to the forewings and held back over the body at rest, as in damselflies. It has more recently been recognized that the genus Epiophlebia shares a more recent ancestor with dragonflies (having become separated from these in and around the uplifting of the Himalayas[1][2]), and the group has accordingly been reclassified as an infraorder within the dragonflies. Very recently [3] a third species, Epiophlebia sinensis, have been described from Heilongjiang province in northeast China, bridging the Epiophlebia distribution gap between Nepal and Japan. And a fourth species is only known from larval material from South China.[4]
QUATERNION IS GROUPS OF FOUR
Quaternions[edit]
Further information: Quaternion Eagle
https://en.wikipedia.org/wiki/Imperial_Estate#Quaternions
Typical representation of the quaternions (Anton III Wierix 1606). The ten quaternions are shown underneath the emperor flanked by the prince-electors (Archbishop of Trier, Archbishop of Cologne, Archbishop of Mainz; King of Bohemia, Count Palatine, Duke of Saxony, Margrave of Brandenburg).
A "Quaternion Eagle" (each quaternion being represented by four coats of arms on the imperial eagle's remiges) Hans Burgkmair, c. 1510. Twelve quaternions are shown, as follows (eight dukes being divided into two quaternions called "pillars" and "vicars", respectively[1]): Seill ("pillars"), Vicari ("vicars"), Marggrauen (margraves), Lantgrauen (landgraves), Burggrauen (burggraves), Grauen (counts), Semper freie (nobles), Ritter (knights), Stett (cities), Dörfer (villages), Bauern (peasants), Birg (castles).
The so-called imperial quaternions (German: Quaternionen der Reichsverfassung "quaternions of the imperial constitution"; from Latin quaterniō "group of four soldiers") were a conventional representation of the Imperial States of the Holy Roman Empire which first became current in the 15th century and was extremely popular during the 16th century.[2]
Apart from the highest tiers of the emperor, kings, prince-bishops and the prince electors, the estates are represented in groups of four. The number of quaternions was usually ten, in descending order of precedence Dukes (Duces), Margraves (Marchiones), Landgraves (Comites Provinciales), Burggraves (Comites Castrenses), Counts (Comites), Knights (Milites), Noblemen (Liberi), Cities (Metropoles), Villages (Villae) and Peasants (Rustici). The list could be shortened or expandend, by the mid-16th century to as many as 45.[3]
It is likely that this system was first introduced under Emperor Sigismund, who is assumed to have commissioned the frescoes in Frankfurt city hall in 1414.[4]
As has been noted from an early time, this representation of the "imperial constitution" does not in fact represent the actual constitution of the Holy Roman Empire, as some imperial cities appear as "villages" or even "peasants". E.g. the four "peasants" are Cologne, Constance, Regensburg and Salzburg. The Burggrave of Stromburg (or Straburg, Strandeck, and variants) was an unknown entity even at the time. The representation of imperial subjects is also far from complete. The "imperial quaternions" are, rather, a more or less random selection intended to represent pars pro toto the structure of the imperial constitution.
Typical representation of the quaternions (Anton III Wierix 1606). The ten quaternions are shown underneath the emperor flanked by the prince-electors (Archbishop of Trier, Archbishop of Cologne, Archbishop of Mainz; King of Bohemia, Count Palatine, Duke of Saxony, Margrave of Brandenburg).
FOUR WINGS
https://en.wikipedia.org/wiki/Damselfly
In species such as the banded demoiselle, Calopteryx splendens the males have both a darker green body and large dark violet-blue patches on all four wings, which flicker conspicuously in their aerial courtship dances; the females have pale translucent greenish wings.[14]
https://en.wikipedia.org/wiki/Dragonfly
Groundlings (Brachythemis) have brown bands on all four wings
GROUPS OF FOUR USUALLY NOT MORE
https://en.wikipedia.org/wiki/Raccoon
Related females often share a common area, while unrelated males live together in groups of up to four animals to maintain their positions against foreign males during the mating season, and other potential invaders
As of 2005, Mammal Species of the World recognizes 22 subspecies.[28] Four of these subspecies found only on small Central American and Caribbean islands were often regarded as distinct species after their discovery. These are the Bahaman raccoon and Guadeloupe raccoon, which are very similar to each other; the Tres Marias raccoon, which is larger than average and has an angular skull; and the extinct Barbados raccoon
Stanislas Dehaene reports in his book The Number Sense raccoons can distinguish boxes containing two or four grapes from those containing three.[100]
Such a group does not usually consist of more than four individuals
THE FOUR RODENT PEST SPECIES FOURTH DIFFERENThttps://en.wikipedia.org/wiki/Rodent
The "three now cosmopolitan commensal rodent pest species"[119] (the brown rat, the black rat and the house mouse) have been dispersed in association with humans, partly on sailing ships in the Age of Exploration, and with a fourth species in the Pacific, the Polynesian rat (Rattus exulans), have severely damaged island biotas around the world
X SHAPED QUADRANT FOUR- TETRA IS FOUR
https://en.wikipedia.org/wiki/Tetraxylopteris
There were possibly four orders in T. reposana
In both species, the primary xylem strand was central to stems, branches and appendages. In the main stems and branches it was X-shaped in cross-section, corresponding to the four rows of branches. In the final appendages it became circular in cross-section. The xylem development was 'mesarch', i.e. the first maturing protoxylem had later maturing metaxylem on either side. Protoxylem occurred both at the tips of the lobes of the xylem strand and in the centre. The general anatomy of the woody stem resembles that of seed plants.[2][3]
The spore-forming organs or sporangia of Tetraxylopteris were born on a very complex 'fertile branching system'. Firstly the main axis of the system branched twice dichotomously. Then each of the four resulting branches was three times pinnate. Each ultimate unit had an elongated sporangium at its end which split longitudinally to release the spores which were trilete, ranging from around 70 to 170 µm in diameter.[3]
FOUR TYPES
https://en.wikipedia.org/wiki/Macedonian_mouse
The Macedonian mouse (Mus macedonicus) is a species of rodent in the family Muridae and order Rodentia. This rodent lives in the area from eastern Georgia and western Bulgaria to Israel.[2] It is considered part of a Paleoarctic group along with three other types of rodents: M. musculus, M. spicilegus, and M. spretus.[3]
FOUR TYPES
https://en.wikipedia.org/wiki/Macedonian_mouse
The Macedonian mouse (Mus macedonicus) is a species of rodent in the family Muridae and order Rodentia. This rodent lives in the area from eastern Georgia and western Bulgaria to Israel.[2] It is considered part of a Paleoarctic group along with three other types of rodents: M. musculus, M. spicilegus, and M. spretus.[3]
https://en.wikipedia.org/wiki/Four-striped_grass_mouse
The four-striped grass mouse or four-striped grass rat (Rhabdomys pumilio) is a species of rodent in the family Muridae.[1]
It is found throughout the southern half of Africa up to 2,300 metres (7,500 ft) above sea level, extending as far north as the Democratic Republic of the Congo.[2] Its natural habitats are savannas, shrublands, Mediterranean-type shrubby vegetation, hot deserts, arable land, rural gardens, and urban areas.
BECAUSE OF FOUR PAIRS FO CHROMOSOMES- (FOURTH DIFFERENT) FRUIT FLY USED BY BIOLOGISTS AS MODEL ORGANISM- I LEARNED ABOUT THAT IN BIOLOGY CLASS AT UCSD
https://en.wikipedia.org/wiki/Drosophila_melanogaster
D. melanogaster continues to be widely used for biological research in studies of genetics, physiology, microbial pathogenesis, and life history evolution. It is typically used because it is an animal species that is easy to care for, has four pairs of chromosomes, breeds quickly, and lays many eggs
https://en.wikipedia.org/wiki/Island_raccoon
The term island raccoons is used as a generic term for four endangered and one extinct subspecies or species of raccoon (Procyon) endemic on small Central American and Caribbean islands, such as Cozumel and Guadeloupe.[1] Other subspecies of raccoon living on islands, like that of the common raccoon (Procyon lotor) native to the Florida Keys, are generally not included under this term, since it was established at a time when all five "island raccoons" were considered distinct species. The five populations are:
Bahaman raccoon (Procyon lotor maynardi): subspecies of the common raccoon endemic on New Providence Island in the Bahamas
Barbados raccoon (Procyon lotor gloveralleni): extinct subspecies of the common raccoon endemic on Barbados until 1964
Cozumel raccoon (Procyon pigmaeus): species endemic on Cozumel
Guadeloupe raccoon (Procyon lotor minor): subspecies of the common raccoon endemic on the two main islands Basse-Terre Island and Grande-Terre of Guadeloupe, which is assumed consubspecific (of the same subspecies) with the Bahaman raccoon
Tres Marias raccoon (Procyon lotor insularis): subspecies of the common raccoon endemic on the two main islands María Madre and María Magdalena of the Islas Marías, which is probably extinct on María Magdalena
FOUR MEMBERS
https://en.wikipedia.org/wiki/Neurotrophin
DevBio.com - 'Neurotrophin Receptors: The neurotrophin family consists of four members: nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), and neurotrophin 4 (NT-4)' (April 4, 2003)
According to the United States National Library of Medicine's medical subject headings, the term neurotrophin may be used as a synonym for neurotrophic factor,[4] but the term neurotrophin is more generally reserved for four structurally related factors: nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4).[5] The term neurotrophic factor generally refers to these four neurotrophins, the GDNF family of ligands, and ciliary neurotrophic factor (CNTF), among other biomolecules.[5][6] Neurotrophin-6 and neurotrophin-7 also exist but are only found in zebrafish.[7]
https://en.wikipedia.org/wiki/Fern
There are four particular types of habitats that ferns are found in: moist, shady forests; crevices in rock faces, especially when sheltered from the full sun; acid wetlands including bogs and swamps; and tropical trees, where many species are epiphytes (something like a quarter to a third of all fern species[15]).
FOUR SPECIES
https://en.wikipedia.org/wiki/Bamboo_rat
The bamboo rats are four species of rodents of the subfamily Rhizomyinae. They are the sole living representatives of the tribe Rhizomyini. All are found in the eastern half of Asia.
The species are:
The Chinese bamboo rat, Rhizomys sinensis, found in central and southern China, northern Burma, and Vietnam;
The hoary bamboo rat, R. pruinosus, found from Assam in India to southeastern China and the Malay Peninsula;
The Sumatra, Indomalayan, or large bamboo rat, R. sumatrensis, found in Yunnak, Indochina, the Malay Peninsula and Sumatra.
The lesser bamboo rat, Cannomys badius, found in Nepal, Assam, northern Bangladesh, Burma, Thailand, Laos, Cambodia and northern Vietnam.
FOUR GENERA
https://en.wikipedia.org/wiki/Deomyinae
The subfamily Deomyinae consists of four genera of mouse-like rodents that were placed in the subfamilies Murinae and Dendromurinae until very recently.
The four genera and 54 species included in the Deomyinae are:
Subfamily Deomyinae
Genus Acomys - spiny mice
Western Saharan spiny mouse, Acomys airensis
Cairo spiny mouse, Acomys cahirinus
Chudeau's spiny mouse, Acomys chudeaui
Asia Minor spiny mouse, Acomys cilicicus
Gray spiny mouse, Acomys cineraceus
Eastern spiny mouse, Acomys dimidiatus
Fiery spiny mouse, Acomys ignitus
Johan's spiny mouse, Acomys johannis
Kemp's spiny mouse, Acomys kempi
Louise's spiny mouse, Acomys louisae
Crete spiny mouse, Acomys minous
Mullah spiny mouse, Acomys mullah
Cyprus spiny mouse, Acomys nesiotes
Percival's spiny mouse, Acomys percivali
Golden spiny mouse, Acomys russatus
Seurat's spiny mouse, Acomys seurati
Southern African spiny mouse, Acomys spinosissimus
Cape spiny mouse, Acomys subspinosus
Wilson's spiny mouse, Acomys wilsoni
Genus Deomys
Link rat, Deomys ferrugineus
Genus Lophuromys - brush-furred mice
Subgenus Kivumys
Yellow-bellied brush-furred rat, Lophuromys luteogaster
Medium-tailed brush-furred rat, Lophuromys medicaudatus
Woosnam's brush-furred rat, Lophuromys woosnami
Subgenus Lophuromys
Angolan brush-furred mouse, Lophuromys angolensis
Ansorge's brush-furred mouse, Lophuromys ansorgei
Gray brush-furred rat, Lophuromys aquilus
Short-tailed brush-furred rat, Lophuromys brevicaudus
Brown brush-furred mouse, Lophuromys brunneus
Chercher Mountains brush-furred mouse, Lophuromys chercherensis
Ethiopian forest brush-furred rat, Lophuromys chrysopus
Dieterlen's brush-furred mouse, Lophuromys dieterleni
Dudu's brush-furred mouse, Lophuromys dudui
Eisentraut's brush-furred rat, Lophuromys eisentrauti
Yellow-spotted brush-furred rat, Lophuromys flavopunctatus
Hutterer's brush-furred mouse, Lophuromys huttereri
Kilonzo's brush-furred mouse, Lophuromys kilonzoi
Lophuromys laticeps
Lophuromys machangui
Makundi's brush-furred mouse, Lophuromys makundii
Lophuromys margarettae
Black-clawed brush-furred rat, Lophuromys melanonyx
Menagesha brush-furred mouse, Lophuromys menageshae
Fire-bellied brush-furred rat, Lophuromys nudicaudus
False rusty-bellied brush-furred rat, Lophuromys pseudosikapusi
Rahm's brush-furred rat, Lophuromys rahmi
Lophuromys rita
Mount Cameroon brush-furred rat, Lophuromys roseveari
Sabuni's brush-furred mouse, Lophuromys sabunii
Rusty-bellied brush-furred rat, Lophuromys sikapusi
Lophuromys simensis
Stanley's brush-furred mouse, Lophuromys stanleyi
Verhagen's brush-furred mouse, Lophuromys verhageni
Zena brush-furred mouse, Lophuromys zena
Genus Uranomys
Rudd's mouse, Uranomys ruddi
FOUR SPECIES THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Hydromys
Hydromys is a genus of rodents in the subfamily Murinae. Three species are endemic to New Guinea and nearby islands. The fourth species, the rakali, is also found on Australia. The most recently discovered member of this genus was described in 2005.
List of species[edit]
Genus Hydromys - water rats
Rakali, Hydromys chrysogaster E. Geoffroy, 1804
Western water rat, Hydromys hussoni Musser and Piik, 1982
New Britain water rat, Hydromys neobrittanicus Tate and Archbold, 1935
Ziegler's water rat, Hydromys ziegleri Helgen, 2005
Note: Hydromys habbema Tate and Archbold, 1941 and Hydromys shawmayeri (Hinton, 1943) are placed within Baiyankamys after Helgen, 2005.
FOUR SPECIES
https://en.wikipedia.org/wiki/Thallomys
Thallomys is a genus (biology) of rodent in the family Muridae endemic to Africa.[1] It contains four species:
Thallomys loringi
Thallomys nigricauda
Thallomys paedulcus
Thallomys shortridgei
FOUR SPECIES
https://en.wikipedia.org/wiki/Crateromys
Crateromys is a genus of rodent, native to the Philippines, in the family Muridae. It contains four species:
Dinagat bushy-tailed cloud rat (Crateromys australis)
Giant bushy-tailed cloud rat (Crateromys schadenbergi)
Panay cloudrunner (Crateromys heaneyi)
Ilin Island cloudrunner (Crateromys paulus)
FOUR SPECIES
https://en.wikipedia.org/wiki/Musseromys
Musseromys is a genus of rodent in the family Muridae. Four species are known, all from Luzon, Philippines:[1][2]
Musseromys anacuao
Musseromys beneficus
Musseromys gulantang
Musseromys inopitatus
http://www.worldatlas.com/articles/the-sixteen-species-of-old-world-vultures-living-today.html
The Sixteen Species Of Old World Vultures Living Today
https://en.wikipedia.org/wiki/Oryzomyini
Weksler's analyses suggested that oryzomyines fall into four major clades, which were largely congruent across his analyses of morphology and IRBP, but support for all of those was limited and the placement of some genera remained unclear. He dubbed these clades "clade A" through "clade D". Some analyses supported a relationship between clades C and D, which in turn were related to clade B, with clade A at a basal position, but other analyses could not resolve the relationships among the major clades.[18] The four clades are as follows:
Clade A includes only Scolomys and Zygodontomys, but support for a relationship between those morphologically and ecologically dissimilar genera was not strong.[20]
Clade B includes at least Oecomys, Handleyomys, Euryoryzomys, Transandinomys, Hylaeamys, and Nephelomys, the latter four of which were included in Oryzomys until 2006.[21] Amphinectomys and Mindomys were also recovered in the clade in some analyses,[22] but the former, for which most morphological characters are unknown, is more likely related to Nectomys within clade D[23] and the relations of the latter, a poorly known yet unique animal, are obscure as some analyses suggest it is a basal member of Oryzomyini.[24] There is little support for all intergeneric relationships within the clade.[18]
Clade C includes Oligoryzomys, Neacomys, Microryzomys, and Oreoryzomys, which was placed in Oryzomys until 2006.[21] No intergeneric relationships within this clade received substantial support.[18]
Clade D includes Drymoreomys,[25] Eremoryzomys, Cerradomys, Sooretamys, Oryzomys, Lundomys, Pseudoryzomys, Holochilus, Aegialomys, Nesoryzomys, Melanomys, Sigmodontomys, Nectomys,[21] most likely Amphinectomys,[23] and the extinct Megalomys,[26] Agathaeromys,[27] and Pennatomys.[28] Eremoryzomys, Cerradomys, Sooretamys, and Aegialomys were included in Oryzomys before 2006.[21] There is some support for a basal placement of Eremoryzomys within this clade and for two major groups of related genera, one including Holochilus, Lundomys, and Pseudoryzomys and the other Nectomys, Amphinectomys, Sigmodontomys, Melanomys, Aegialomys, and Nesoryzomys,[29] with the extinct Megalomys and Pennatomys.[30] The Holochilus–Lundomys–Pseudoryzomys group also includes the extinct Noronhomys and Carletonomys.[31] Oryzomys may be its closest relative, but it is possible that this arrangement is the result of a convergent development of adaptations to a life in the water in the two groups.[32] Within the group of Nectomys and related genera, there is some support for a core group that excludes Aegialomys and Nesoryzomys and for two subclades within the core group, one including Nectomys and Amphinectomys and the other Melanomys and Sigmodontomys.[29]
FOUR SUBFAMILIES
https://en.wikipedia.org/wiki/Halictidae
The Halictidae belong to the hymenopteran superfamily Apoidea, series Anthophila. The oldest fossil record of Halictidae dates back to Early Eocene[13] with a number of species, such as Neocorynura electra[14] and Augochlora leptoloba[15] known from amber deposits. Currently, the family is divided into four subfamilies
https://en.wikipedia.org/wiki/Oryzomys_couesi
Using the genetic species concept, the authors suggested that the four groups they found within O. couesi should be recognized as distinct species. If this suggestion is followed, the eastern subclade would retain the name Oryzomys couesi, the western group would be named Oryzomys mexicanus, and the appropriate names for the Panamanian and Costa Rican species remain unclear
Goldman grouped four subspecies of couesi from the interior plateaus of central Mexico together—albiventer, crinitus, aztecus, and regillus.[52] Three of those (albiventer from Jalisco,[53] crinitus from the Distrito Federal,[50] and aztecus from Morelos)[49] were described by Merriam in 1901, and Goldman had himself described regillus from Michoacán in 1915.[51] According to Goldman, aztecus is pale and large-toothed,[54] crinitus is large, dark and large-toothed,[55] regillus is large and dark,[52] and albiventer is large and relatively pale.[56]
https://en.wikipedia.org/wiki/Oryzomys_nelsoni
Clinton Hart Merriam identified the mammals they obtained, including four specimens of Oryzomys nelsoni, which were deposited in the United States National Museum and remain there
Total length in the four known specimens is 282 to 344 mm (11.1 to 13.5 in), averaging 322 mm (12.7 in); head and body length is 122 to 153 mm (4.8 to 6.0 in), averaging 140.5 mm (5.53 in); tail length is 160 to 191 mm (6.3 to 7.5 in), averaging 181.5 mm (7.15 in); and hindfoot length is 35 to 39 mm (1.4 to 1.5 in), averaging 37.3 mm (1.47 in).[23]
https://en.wikipedia.org/wiki/Oryzomys_antillarum
In his History of Jamaica (1774), Edward Long recognized four Jamaican rats: Browne's "Water-Rat", termed the "Charles-price rat", which Long regarded as identical with the European water vole (Arvicola);[38] the "black house-rat", said to have been brought from England; and two he said were indigenous. The larger of those was a grayish "cane-rat"[39] and the smaller was a reddish "field-rat" as large as the English mole (the European mole, Talpa europaea).[40] Ray considered that the last may simply have been the house mouse, since the size of an English mole would be too small for Oryzomys.[41
https://en.wikipedia.org/wiki/Elk
Recent DNA studies suggest that there are no more than three or four subspecies of elk.
THE FOUR SUBSPECIES OF THE WILD TURKEY
http://www.turkeyhunting247.com/Article/the-four-subspecies-of-the-wild-turkey-Page1.htm
[Introduction]
0:36 Announcer: Primos Hunting Calls presents Mastering the Art of Spring Turkey Hunting.
0:45 In the United States, there are four subspecies of the American wild turkey. There's the Eastern, the Merriam's, Rio Grande and the Osceola.
https://en.wikipedia.org/wiki/Marsh_rice_rat
In his 1918 revision of North American Oryzomys, Edward Alphonso Goldman again recognized all these as a single species, Oryzomys palustris. He distinguished four subspecies, which he said formed a "closely intergrading series"—O. p. palustris from New Jersey to southeastern Mississippi and eastern Missouri; O. p. natator in central Florida; O. p. coloratus (including O. natator floridanus Merriam) in southern Florida; and O. p. texensis from western Mississippi and southeastern Kansas to eastern Texas.
https://en.wikipedia.org/wiki/Central_Asian_red_deer
The Central Asian Red Deer comprises four subspecies, Tibetan red deer, MacNeill's deer, Kansu red deer and Kashmir stag.[2]
https://en.wikipedia.org/wiki/Osprey
Four subspecies are usually recognized, one of which has recently been given full species status (see below). Despite its propensity to nest near water, the osprey is not classed as a sea eagle.
There are four generally recognised subspecies, although differences are small, and ITIS lists only the first two.[3]
P. h. haliaetus – (Linnaeus, 1758): Palearctic.[7]
P. h. carolinensis – (Gmelin, 1788): North America. This form is larger, darker bodied and has a paler breast than nominate haliaetus.[7]
P. h. ridgwayi – Maynard, 1887: Caribbean islands. This form has a very pale head and breast compared with nominate haliaetus, with only a weak eye mask.[7] It is non-migratory. Its scientific name commemorates American ornithologist Robert Ridgway.[8]
P. h. cristatus – (Vieillot, 1816): coastline and some large rivers of Australia and Tasmania. The smallest and most distinctive subspecies, also non-migratory.[7]
FOUR TYPES OF BENAL TIGER
The four faces of the Bengal tiger
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15 April 2009: Displayed for the first time in a specially constructed studio in South Carolina, these images show the four varieties of Bengal tiger.
"There are only four distinct types of Bengal tiger in the world and they are all in this amazing photo shoot," says Dr Bhagavan Antle of The Institute of Greatly Endangered and Rare Species (T.I.G.E.R.S), who brought these majestic animals to the studio. Dr Antle believes the images give away the characteristics of behaviour, age and personality of each tiger. "Like human photographs, you can see the difference in their age as some of them look a little more grizzled and haggard than others"
FOUR SPECIES
https://en.wikipedia.org/wiki/Arripis_trutta
Arripis trutta, known as kahawai in New Zealand and as the Eastern Australian salmon in Australia, is one of four species of marine fish within the Arripis genus, found in cooler waters around the south eastern coast of Australia and New Zealand. Although it is referred to as a salmon in Australia and its species epithet trutta is the Latin for trout, it is not related to salmons or trouts of the family Salmonidae.
FOUR SPECIES
https://en.wikipedia.org/wiki/Arripis
Arripis is a genus of marine fishes from Australia and New Zealand, known as Australian salmon, kahawai and Australian herring
There are currently four recognised species in this genus.[1] The ranges of the species may overlap to some extent, but can be described as:
Arripis georgianus (Valenciennes, 1831) (ruff, tommy ruff, Australian ruff, Australian herring): Gippsland Lakes, Victoria to Shark Bay, Western Australia
Arripis trutta (J. R. Forster, 1801) (Australian salmon, eastern Australian salmon, kahawai): From western Victoria to New Zealand, including the islands of Tasmania, Lord Howe, and Norfolk
Arripis truttaceus (G. Cuvier, 1829) (western Australian salmon): Western Australia to Victoria and Tasmania
Arripis xylabion Paulin, 1993 (northern kahawai, kermadec kahawai): New Zealand, west to Lord Howe, Norfolk and Kermadec Islands
FOUR SPECIES
https://en.wikipedia.org/wiki/Cissa_(genus)
Cissa is a genus of relatively short-tailed magpies, though sometimes known as hunting cissas, that reside in the forests of tropical and subtropical southeast Asia and adjacent regions. The four species are quite similar with bright red bills, a mainly green plumage, black mask, and rufous wings. Due to excess exposure to sunlight (and, possibly, a low-carotenoid diet), they often appear rather turquoise (instead of green) in captivity. They are carnivorous, and mainly feed on arthropods and small vertebrates.
Species[edit]
The genus Cissa contains four species:
Species of Cissa
Common and binomial names Image Description Range
Common green magpie
(Cissa chinensis) Cissa chinensis -Chiang Mai Zoo, Thailand-8a.jpg Lower Himalayas to mainland southeast Asia, as well as Borneo and Sumatra
Indochinese green magpie
(Cissa hypoleuca) Cissa hypoleucor concolor qtl1.jpg Mainland southeast Asia and adjacent parts of China
Javan green magpie
(Cissa thalassina) Java
Bornean green magpie
(Cissa jefferyi) CissaJefferyiKeulemans.jpg Borneo
FOUR SPECIES
https://en.wikipedia.org/wiki/Pica_(genus)
Pica is the genus of four species of birds in the family Corvidae in both the New World and the Old. The genus name Pica is derived from the Latin name for the Eurasian magpie.[1]
They have long tails and have predominantly black and white markings. One species ranges widely from Europe through Asia, one occurs in western North America and the third is restricted to California. They are usually considered closely related to the blue and green magpies of Asia, but recent research suggests their closest relatives are instead the Eurasian crows.[2]
Two or three species were generally recognized, the Yellow-billed and one or two black-billed ones. Recent research has cast doubt on the taxonomy of the Pica magpies.[3] P. hudsonia and P. nuttalli are each other's closest relatives, but may not be different species. If they are, however, at least the Korean race of P. pica would have to be considered a separate species, too.
Eurasian magpie, Pica pica – Europe and Asia
Korean magpie, Pica (pica) sericea – eastern Asia
Yellow-billed magpie, Pica nuttalli – California
Black-billed magpie, Pica hudsonia – western half of North America
THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Cuban_crow
The Cuban crow (Corvus nasicus) is one of four species of crow that occur on a few key islands in the Caribbean. It is closely related to the white-necked crow (C. leucognaphalis) and Jamaican crow (C. jamaicensis), with which it shares similar features. The fourth Caribbean crow, the palm crow (C. palmarum), is a later arrival in evolutionary terms and shows characteristics more akin to North American species such as the fish crow (C. ossifragus), which it is probably closely related to.
https://en.wikipedia.org/wiki/Bos
Bos can be divided into four subgenera: Bos, Bibos, Novibos, and Poephagus
FOUR CHAMBERED STOMACHS
https://en.wikipedia.org/wiki/Cattle
Cattle have one stomach with four compartments, the rumen, reticulum, omasum, and abomasum
A cow's udder contains two pairs of mammary glands, (commonly referred to as teats) creating four "quarters".[38] The front ones are referred to as fore quarters and the rear ones rear quarters.[39]
Cattle have a well-developed sense of taste and can distinguish the four primary tastes (sweet, salty, bitter and sour).
Shigella species are classified by four serogroups:
https://en.wikipedia.org/wiki/Shigella
Serogroup A: S. dysenteriae (15 serotypes)[9]
Serogroup B: S. flexneri (six serotypes)
Serogroup C: S. boydii (19 serotypes)[10]
Serogroup D: S. sonnei (one serotype)
https://en.wikipedia.org/wiki/Cavalier_King_Charles_Spaniel
FOUR COLOURS
The Cavalier King Charles Spaniel is a small spaniel classed as a toy dog by The Kennel Club and the American Kennel Club.[2] It originated in the United Kingdom and is one of the more popular breeds in many countries. Since 2000, it has grown in popularity in the United States and ranks as the 18th most popular pure-breed in the United States (2013 Registration Statistics).[2] It has a silky, smooth coat and commonly a smooth undocked tail. The breed standard recognizes four colours: Blenheim (chestnut and white), Tricolor (black/white/tan), Black and Tan, and Ruby.[2] The breed is generally friendly, affectionate and good with both children and other animals; however, they require a lot of human interaction. The expected average lifespan of a Cavalier King Charles Spaniel is under ten years.[3]
FOUR BREEDS
https://en.wikipedia.org/wiki/Swiss_mountain_dog
Sennenhund, called Swiss mountain dogs or Swiss cattle dogs in English, are a type of dog originating in the Swiss Alps. The Sennenhund are farm dogs of the general molosser type. There are four breeds of Sennenhund, all sporting a unique tricolor coat. While the two larger ones share a heavy build and a calm temperament, the two smaller ones are more agile. The breeds range from medium in size to very large. The name Sennenhund refers to people called Senn or Senner, Swiss alpine herdsmen and dairymen, and does not translate as "mountain" or "cattle".
Contents [hide]
1 Breeds
2 History
3 Similar breeds
4 Tri-color
5 Breed examples
6 See also
7 References
8 External links
Breeds[edit]
A Grosser Schweizer Sennenhund (left) and an Entlebucher Sennenhund (right)
This table shows the relative sizes of the breeds, with the original breed name followed by the most popular English version of the breed name.
Breed Height at withers Weight
Grosser Schweizer Sennenhund (Greater Swiss Mountain Dog) 23.5–28.5 in (60–72 cm) 110–140 lb (50–70 kg)
Berner Sennenhund (Bernese Mountain Dog) 23–27½ in (58–70 cm) 65–120 lb (29½–54½ kg)
Appenzeller Sennenhund (Appenzeller) 18½–23 in (47–58 cm) 49–70 lb (22–32 kg)
Entlebucher Sennenhund (Entlebucher Mountain Dog) 19–20 in (48–50 cm) 45–65 lb (20½–30 kg)
The four Sennenhund breeds are well known in Switzerland and the rest of Europe. In the United States, the Bernese Mountain Dog has become somewhat popular, while the other breeds are promoted as rare to those seeking unique pets.
https://en.wikipedia.org/wiki/Pointer_(dog_breed)
Through both history and anatomical evaluation, at least four breeds appear to have been instrumental in Pointer crosses: Greyhounds, Foxhounds, Bloodhounds, and Bull Terriers.[5] Each of these were established breeds with unique qualities the Pointer could use to do its job.[5]
FOUR CANNALS INSTEAD OF THREE- FOURTH ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Endodontic_therapy
Root canal treated teeth may fail to heal, for example if the dentist does not find, clean and fill all of the root canals within a tooth. On a maxillary molar, there is a more than 50% chance that the tooth has four canals instead of just three. But the fourth canal, often called a "mesio-buccal 2", tends to be very difficult to see and often requires special instruments and magnification in order to see it (most commonly found in first maxillary molars; studies have shown an average of 76% up to 96% of such teeth with the presence of an MB2 canal). This infected canal may cause a continued infection or "flare up" of the tooth. Any tooth may have more canals than expected, and these canals may be missed when the root canal is performed. Sometimes canals may be unusually shaped, making them impossible to clean and fill completely; some infected material may remain in the canal. Sometimes the canal filling does not fully extend to the apex of the tooth, or it does not fill the canal as densely as it should. Sometimes a tooth root may be perforated while the root canal is being treated, making it difficult to fill the tooth. The perforation may be filled with a root repair material, such as one derived from natural cement called mineral trioxide aggregate (MTA). A specialist can often re-treat failing root canals, and these teeth will then heal, often years after the initial root canal procedure.[citation needed]
FOUR SUBFAMILIES CACTUS
https://en.wikipedia.org/wiki/Cactus
The ICSG classification of the cactus family recognizes four subfamilies, the largest of which is divided into nine tribes. The subfamilies are:[29]
The four cactus subfamilies
Pereskioideae: Pereskia aculeata
Opuntioideae: Opuntia chlorotica
Maihuenioideae: Maihuenia poeppigii
Cactoideae: Mammillaria elongata
Subfamily Pereskioideae K. Schumann
The only genus is Pereskia. It has features considered closest to the ancestors of the Cactaceae. Plants are trees or shrubs with leaves; their stems are smoothly round in cross section, rather than being ribbed or having tubercles.[29] Two systems may be used in photosynthesis, both the "normal" C3 mechanism and crassulean acid metabolism (CAM)—an "advanced" feature of cacti and other succulents that conserves water.[9]
Subfamily Opuntioideae K. Schumann
Some 15 genera are included in this subfamily. They may have leaves when they are young, but these are lost later. Their stems are usually divided into distinct "joints" or "pads" (cladodes).[29] Plants vary in size from the small cushions of Maihueniopsis[32] to treelike species of Opuntia, rising to 10 m (33 ft) or more.[33]
Subfamily Maihuenioideae P. Fearn
The only genus is Maihuenia, with two species, both of which form low-growing mats.[12] It has some features that are primitive within the cacti. Plants have leaves, and crassulean acid metabolism is wholly absent.[29]
Subfamily Cactoideae
Divided into nine tribes, this is the largest subfamily, including all the "typical" cacti. Members are highly variable in habit, varying from tree-like to epiphytic. Leaves are normally absent, although sometimes very reduced leaves are produced by young plants. Stems are usually not divided into segments, and are ribbed or tuberculate. Two of the tribes, Hylocereeae and Rhipsalideae, contain climbing or epiphytic forms with a rather different appearance; their stems are flattened and may be divided into segments.[
https://en.wikipedia.org/wiki/Bichon_Frise
FOUR GROUPS
The Bichons were divided into four categories: the Bichon Maltese, the Bichon Bolognaise, the Bichon Havanese and the Bichon Tenerife (this breed). All originated in the Mediterranean area
FOURTH ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Fourth_Estate
The Fourth Estate (or fourth power) is a societal or political force or institution whose influence is not consistently or officially recognized. "Fourth Estate" most commonly refers to the news media, especially print journalism or "the press". The term makes implicit reference to the earlier division of the three estates of the realm: the clergy, the nobility, and the commoners. The equivalent term fourth power, used in many European languages, (see: fr:Quatrième pouvoir) refers to the separation of powers into a legislature, an executive, and a judiciary.
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FOUR GENERA
https://en.wikipedia.org/wiki/Polystachyinae
Polystachyinae is a subtribe within the tribe Vandeae in family Orchidaceae. It consists of 4 genera and about 228 known species. The type genus of this subtribe is Polystachya. The group is pantropical, being native to tropical Africa primarily, but also to tropical America.[1] Members of this group are epiphytic and are distinguished from the other subtribes in the tribe Vandeae by their sympodial growth habit and the presence of four pollinia. Pollination is mostly by small species of bees, however some species (e.g. Polystachya concrete) exhibit auto-pollination.[2]
Genera[edit]
Genera in this subtribe are listed below:
Hederorkis Thouars, 1809 (2 sp.)
Imerinaea Schltr., 1924 (1 sp.)
Neobenthamia Rolfe, 1891 (1 sp.)
Polystachya Hook., 1824 (224 spp.)
FOUR SUBFAMILIES
https://en.wikipedia.org/wiki/Stag_beetle
Stag beetles are a group of about 1,200 species of beetles in the family Lucanidae, presently classified in four subfamilies.[1] Some species grow up to over 12 cm (4.7 in), but most are about 5 cm (2.0 in).
Protein tertiary structure can be divided into four main classes based on the secondary structural content of the domain.[23]
https://en.wikipedia.org/wiki/Protein_domain
All-α domains have a domain core built exclusively from α-helices. This class is dominated by small folds, many of which form a simple bundle with helices running up and down.
All-β domains have a core composed of antiparallel β-sheets, usually two sheets packed against each other. Various patterns can be identified in the arrangement of the strands, often giving rise to the identification of recurring motifs, for example the Greek key motif.[24]
α+β domains are a mixture of all-α and all-β motifs. Classification of proteins into this class is difficult because of overlaps to the other three classes and therefore is not used in the CATH domain database.[13]
α/β domains are made from a combination of β-α-β motifs that predominantly form a parallel β-sheet surrounded by amphipathic α-helices. The secondary structures are arranged in layers or barrels.
TRANSMEMBRANE PROTEINS FOUR TYPES- NOTICE HOW THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Transmembrane_protein
Classification by topology[edit]
This classification refers to the position of the N- and C-terminal domains. Types I, II, and III are single-pass molecules, while type IV are multiple-pass molecules. Type I transmembrane proteins are anchored to the lipid membrane with a stop-transfer anchor sequence and have their N-terminal domains targeted to the ER lumen during synthesis (and the extracellular space, if mature forms are located on plasmalemma). Type II and III are anchored with a signal-anchor sequence, with type II being targeted to the ER lumen with its C-terminal domain, while type III have their N-terminal domains targeted to the ER lumen. Type IV is subdivided into IV-A, with their N-terminal domains targeted to the cytosol and IV-B, with an N-terminal domain targeted to the lumen.[5] The implications for the division in the four types are especially manifest at the time of translocation and ER-bound translation, when the protein has to be passed through the ER membrane in a direction dependent on the type.
Classification by topology[edit]
This classification refers to the position of the N- and C-terminal domains. Types I, II, and III are single-pass molecules, while type IV are multiple-pass molecules. Type I transmembrane proteins are anchored to the lipid membrane with a stop-transfer anchor sequence and have their N-terminal domains targeted to the ER lumen during synthesis (and the extracellular space, if mature forms are located on plasmalemma). Type II and III are anchored with a signal-anchor sequence, with type II being targeted to the ER lumen with its C-terminal domain, while type III have their N-terminal domains targeted to the ER lumen. Type IV is subdivided into IV-A, with their N-terminal domains targeted to the cytosol and IV-B, with an N-terminal domain targeted to the lumen.[5] The implications for the division in the four types are especially manifest at the time of translocation and ER-bound translation, when the protein has to be passed through the ER membrane in a direction dependent on the type.
FOUR TRANSMEMBRANE DOMAINS
https://en.wikipedia.org/wiki/Claudin
Claudins are a family of proteins that are the most important components of the tight junctions, where they establish the paracellular barrier that controls the flow of molecules in the intercellular space between the cells of an epithelium. They have four transmembrane domains, with the N-terminus and the C-terminus in the cytoplasm.
FOUR ALPHA HELIX VERY COMMON IN PROTEINS
https://en.wikipedia.org/wiki/Alpha_helix
Coiled-coil α helices are highly stable forms in which two or more helices wrap around each other in a "supercoil" structure. Coiled coils contain a highly characteristic sequence motif known as a heptad repeat, in which the motif repeats itself every seven residues along the sequence (amino acid residues, not DNA base-pairs). The first and especially the fourth residues (known as the a and d positions) are almost always hydrophobic; the fourth residue is typically leucine - this gives rise to the name of the structural motif called a leucine zipper, which is a type of coiled-coil. These hydrophobic residues and pack together in the interior of the helix bundle. In general, the fifth and seventh residues (the e and g positions) have opposing charges and form a salt bridge stabilized by electrostatic interactions. Fibrous proteins such as keratin or the "stalks" of myosin or kinesin often adopt coiled-coil structures, as do several dimerizing proteins. A pair of coiled-coils - a four-helix bundle - is a very common structural motif in proteins. For example, it occurs in human growth hormone and several varieties of cytochrome. The Rop protein, which promotes plasmid replication in bacteria, is an interesting case in which a single polypeptide forms a coiled-coil and two monomers assemble to form a four-helix bundle.
Tetrapeptide
From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Tetrapeptide
A tetrapeptide (example Val-Gly-Ser-Ala) with
green marked amino end (L-Valine) and
blue marked carboxyl end (L-Alanine).
A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors in protein-protein signaling. Present in nature are both linear and cyclic tetrapeptides, tetrapeptides may be cyclized by a fourth peptide bond or other covalent bonds.
Examples of tetrapeptides are:
Tuftsin (L-threonyl-L-lysyl-L-prolyl-L-arginine) is a peptide related primarily to the immune system function.
Rigin (glycyl-L-glutaminyl-L-prolyl-L-arginine) is a tetrapeptide with functions similar to those of tuftsin.
Postin (Lys-Pro-Pro-Arg) is the N-terminal tetrapeptide of cystatin C and an antagonist of tuftsin.
Endomorphin-1 (H-Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH2) are peptide amides with the highest known affinity and specificity for the μ opioid receptor.
Morphiceptin (H-Tyr-Pro-Phe-Pro-NH2) is a casomorphin peptide isolated from β-casein.
Gluten exorphines A4 (H-Gly-Tyr-Tyr-Pro-OH) and B4 (H-Tyr-Gly-Gly-Trp-OH) are peptides isolated from gluten.
Tyrosine-MIF-1 (H-Tyr-Pro-Leu-Gly-NH2) is an endogenous opioid modulator.
Tetragastrin (N-((phenylmethoxy)carbonyl)-L-tryptophyl-L-methionyl-L-aspartyl-L-phenylalaninamide) is the C-terminal tetrapeptide of gastrin. It is the smallest peptide fragment of gastrin which has the same physiological and pharmacological activity as gastrin.
Kentsin (H-Thr-Pro-Arg-Lys-OH) is a contraceptive peptide first isolated from female hamsters.
Achatin-I (glycyl-phenylalanyl-alanyl-aspartic acid) is a neuroexcitatory tetrapeptide from giant African snail (Achatina fulica).
Tentoxin (cyclo(N-methyl-L-alanyl-L-leucyl-N-methyl-trans-dehydrophenyl-alanyl-glycyl)) is a natural cyclic tetrapeptide produced by phytopathogenic fungi from genus Alternaria.
Rapastinel (H-Thr-Pro-Pro-Thr-NH2) is a partial agonist of the NMDA receptor.
HC-toxin, cyclo(D-Pro-L-Ala-D-Ala-L-Aeo), where Aeo is 2-amino-8-oxo-9,10-epoxy decanoic acid, is a virulence factor for the fungus Cochliobolus carbonum on its host, maize.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Endomorphin
The endomorphins are a group of endogenous opioid peptides consisting of endomorphin-1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (Tyr-Pro-Phe-Phe-NH2). They are tetrapeptides with the highest known affinity and selectivity for the μ-opioid receptor
THERE ARE FOUR KNOWN GLUTEN EXPORPHINS AND THEY ARE TETRAPEPTIDES
https://en.wikipedia.org/wiki/Gluten_exorphin
Gluten exorphins are a group of opioid peptides formed during digestion of the gluten protein. It has been hypothesized that people with autism and schizophrenia have abnormal leakage from the gut of these compounds, which then pass into the brain and disrupt brain function[1] known as the opioid excess theory or a part of leaky gut syndrome. This is partly the basis for the gluten-free, casein-free diet. Two clinical studies of autism patients who followed this diet have found no evidence of benefit.[2][3] Another found evidence of benefit.[4] Another study suggested the diet may present a greater risk to brain development.[5]
There are four known gluten exorphins with known structure:
Contents [hide]
1 Gluten exorphin A5
2 Gluten exorphin B4
3 Gluten exorphin B5
4 Gluten exorphin C
5 References
Gluten exorphin A5[edit]
Structure: H-Gly-Tyr-Tyr-Pro-Thr-OH
Chemical formula: C24H37N5O9
Molecular weight: 599.64 g/mol
Gluten exorphin B4[edit]
Structure: H-Tyr-Gly-Gly-Trp-OH
Chemical formula: C24H27N5O6
Molecular weight: 481.50 g/mol
Gluten exorphin B5[edit]
Structure: H-Tyr-Gly-Gly-Trp-Leu-OH
Chemical formula: C30H38N6O7
Molecular weight: 594.66 g/mol
Gluten exorphin C[edit]
Structure: H-Tyr-Pro-Ile-Ser-Leu-OH
Chemical formula: C29H45N5O8
Molecular weight: 591.70 g/mol
Cuvier, 1817[edit]
https://en.wikipedia.org/wiki/Body_plan
FOUR BODY PLANS
Haeckel's 'Monophyletischer Stambaum der Organismen' from Generelle Morphologie der Organismen (1866) with the three branches Plantae, Protista, Animalia
In his 1817 work, Le Règne Animal, the French zoologist Georges Cuvier combined evidence from comparative anatomy and palaeontology[3] to divide the animal kingdom into four body plans. Taking the central nervous system as the main organ system which controlled all the others, such as the circulatory and digestive systems, Cuvier distinguished four body plans:[4]
I. with a brain and a spinal cord (surrounded by skeletal elements)[4]
II. with organs linked by nerve fibres[4]
III. with two longitudinal, ventral nerve cords linked by a band with two ganglia below the oesophagus[4]
IV. with a diffuse nervous system, not clearly discernible[4]
Grouping animals with these body plans resulted in four branches: vertebrates, molluscs, articulata (including insects and annelids) and zoophytes or radiata.
FOURTH ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Demosponge
However, molecular and morphological evidence show that the Homoscleromorpha do not belong in this class. The Homoscleromorpha was therefore officially taken out of the Demospongiae in 2012, and became the fourth class of phylum Porifera.[6]
FOUR CLASSES OF SPONGE- THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Sponge
Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, is actually phylogenetically well separated. Therefore, they have recently been recognized as the fourth class of sponges.[59][60]
Sponges are divided into classes mainly according to the composition of their skeletons:[17]
Type of cells[17] Spicules[17] Spongin fibers[17] Massive exoskeleton[26] Body form[17]
Calcarea Single nucleus, single external membrane Calcite
May be individual or large masses Never Common.
Made of calcite if present. Asconoid, syconoid, leuconoid or solenoid[61]
Hexactinellida Mostly syncytia in all species Silica
May be individual or fused Never Never Leuconoid
Demospongiae Single nucleus, single external membrane Silica In many species In some species.
Made of aragonite if present.[15][26] Leuconoid
Homoscleromorpha Single nucleus, single external membrane Silica In many species Never Sylleibid or leuconoid
TETRA IS FOUR- SPONGE SYMMETRY
https://en.wikipedia.org/wiki/Sponge_spicule
Tetraxons have four axes, and polyaxons more (description of types to be incorporated from [1]). Sigma-C spicules have the shape of a C.[1]
FOUR QUADRANT SCHEME ABDOMEN
https://en.wikipedia.org/wiki/Quadrant_(abdomen)
The human abdomen is divided into regions by anatomists and physicians for purposes of study, diagnosis, and therapy.[1][2] In the four-region scheme, four quadrants allow localisation of pain and tenderness, scars, lumps, and other items of interest, narrowing in on which organs and tissues may be involved. The quadrants are referred to as the left lower quadrant, left upper quadrant, right upper quadrant and right lower quadrant, as follows below. These terms are not used in comparative anatomy, since most other animals do not stand erect.
The left lower quadrant (LLQ) of the human abdomen is the area left of the midline and below the umbilicus. The LLQ includes the left iliac fossa and half of the left flank region. The equivalent term for animals is left posterior quadrant.
The left upper quadrant (LUQ) extends from the median plane to the left of the patient, and from the umbilical plane to the left ribcage. The equivalent term for animals is left anterior quadrant.
The right upper quadrant (RUQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right ribcage. The equivalent term for animals is right anterior quadrant.
The right lower quadrant (RLQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right inguinal ligament. The equivalent term for animals is right posterior quadrant.
THERE ARE C4 PLANTS AND C3 PLANTS- THE FOURTH IS ALWAYS DIFFERENT AND THERE IS ALWAYS THE DYNAMIC BETWEEN FOUR AND 3
http://w3.marietta.edu/~spilatrs/biol103/photolab/c4photo.html
A brief overview of C4 photosynthesis
The fundamentals of C4 photosynthesis are shown in a simplified form in the figure below. As you will recall, the photosynthesis processes of C4 plants are divided between mesophyll and bundle sheath cells. Two steps of C4 photosynthesis that occur in the mesophyll cells are the light-dependent reactions and a preliminary fixation of CO2 into a molecule called malate.
CO2 is released from malate in the bundle sheath cells, where it is fixed again by Rubisco and the Calvin-Benson cycle. The PEP is then recycled back to the mesophyll cells, and the carbohydrate products of photosynthesis are distributed through the plant.
How does this process help to explain the lower light compensation point and higher light saturation point of C4 plants? Decarboxylation of malate (release of the CO2) creates a higher concentration of CO2 in the bundle sheath cells than that found in photosynthetic cells of C3 plants. CO2 enrichment allows C4 plants to sustain higher rates of photosynthesis. Furthermore, because the concentration of CO2 relative to O2 in bundle sheath cells is higher, rates of photorespiration in C4 plants is lower than in C3 plants. In other words, the rate of "dark respiration" is lower, and the plant has a lower light compensation point.
FOUR CYTOCHROME C- FOUR PROTONS
https://en.wikipedia.org/wiki/Cytochrome_c_oxidase
The enzyme cytochrome c oxidase or Complex IV, EC 1.9.3.1 is a large transmembrane protein complex found in bacteria and the mitochondrion of eukaryotes.
It is the last enzyme in the respiratory electron transport chain of mitochondria (or bacteria) located in the mitochondrial (or bacterial) membrane. It receives an electron from each of four cytochrome c molecules, and transfers them to one oxygen molecule, converting molecular oxygen to two molecules of water. In the process, it binds four protons from the inner aqueous phase to make water, and in addition translocates four protons across the membrane, helping to establish a transmembrane difference of proton electrochemical potential that the ATP synthase then uses to synthesize ATP.
TETRASPORIC FOUR SPORES
https://en.wikipedia.org/wiki/Megaspore
In gymnosperms and flowering plants, the megaspore is produced inside the nucleus of the ovule. During megasporogenesis, a diploid precursor cell, the megasporocyte or megaspore mother cell, undergoes meiosis to produce initially four haploid cells (the megaspores).[1] Angiosperms exhibit three patterns of megasporogenesis: monosporic, bisporic, and tetrasporic, also known as the Polygonum type, the Alisma type, and the Drusa type, respectively. The monosporic pattern occurs most frequently (>70% of angiosperms) and is found in many economically and biologically important groups such as Brassicaceae (e.g., Arabidopsis, Capsella, Brassica), Gramineae (e.g., maize, rice, wheat), Malvaceae (e.g., cotton), Leguminoseae (e.g., beans, soybean), and Solanaceae (e.g., pepper, tobacco, tomato, potato, petunia).[2]
This pattern is characterized by cell plate formation after meiosis 1 & 2, which results in four one-nucleate megaspores, of which three degenerate. The bisporic pattern is characterized by cell plate formation only after meiosis 1, and results in two two-nucleate megaspores, of which one degenerates. The tetrasporic pattern is characterized by cell plates failing to form after either meiosis 1 or 2, and results in one four-nucleate megaspore. Therefore, each pattern gives rise to a single functional megaspore which contains one, two, or four meiotic nuclei, respectively.[2] The megaspore then undergoes megagametogenesis to give rise to the female gametophyte.
TWO GROUPS OF FOUR- TETRASPORIC
https://en.wikipedia.org/wiki/Megaspore
If the monosporic pattern occurred, the single nucleus undergoes mitosis three times, producing an eight-nucleate cell. These eight nuclei are arranged into two groups of four. These groups both send a nucleus to the center of the cell; these become the polar nuclei.
The bisporic and tetrasporic patterns undergo varying processes and result in varying embryo sacs as well. In Lilium which has a tetrasporic pattern, the central cell of the embryo sac is 4N. Therefore, upon fertilization the endosperm will be 5N rather than the typical 3N.[4]
https://en.wikipedia.org/wiki/Apis_dorsata_laboriosa
The term "Himalayan honey bee" is sometimes used more informally, for any of the four varieties of honey bees that are found in the Himalayan region; Apis cerana, Apis florea, Apis dorsata and Apis dorsata laboriosa.
FOUR PARTS
https://en.wikipedia.org/wiki/Vertebral_artery
The vertebral artery may be divided into four parts:
The first part runs upward and backward between the Longus colli and the Scalenus anterior. In front of it are the internal jugular and vertebral veins, and it is crossed by the inferior thyroid artery; the left vertebral is crossed by the thoracic duct also. Behind it are the transverse process of the seventh cervical vertebra, the sympathetic trunk and its inferior cervical ganglion
The second part runs upward through the foramina in the transverse processes of the C6 to C2 vertebræ, and is surrounded by branches from the inferior cervical sympathetic ganglion and by a plexus of veins which unite to form the vertebral vein at the lower part of the neck. It is situated in front of the trunks of the cervical nerves, and pursues an almost vertical course as far as the transverse process of the axis.
The third part issues from the C2 foramen transversarium on the medial side of the Rectus capitis lateralis. It is further subdivided into the vertical part V3v passing vertically upwards, crossing the C2 root and entering the foramen transversarium of C1, and the horizontal part V3h, curving medially and posteriorly behind the superior articular process of the atlas, the anterior ramus of the first cervical nerve being on its medial side; it then lies in the groove on the upper surface of the posterior arch of the atlas, and enters the vertebral canal by passing beneath the posterior atlantoöccipital membrane. This part of the artery is covered by the Semispinalis capitis and is contained in the suboccipital triangle—a triangular space bounded by the Rectus capitis posterior major, the Obliquus superior, and the Obliquus inferior. The first cervical or suboccipital nerve lies between the artery and the posterior arch of the atlas.
The fourth part pierces the dura mater and inclines medialward to the front of the medulla oblongata; it is placed between the hypoglossal nerve and the anterior root of the first cervical nerve and beneath the first digitation of the ligamentum denticulatum. At the lower border of the pons it unites with the vessel of the opposite side to form the basilar artery.
https://en.wikipedia.org/wiki/Low-affinity_nerve_growth_factor_receptor
The neurotrophins are composed of four proteins, all of which bind to the LNGFR: nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4).
THERE ARE FOUR SUBUNITS EACH WITH SIX SEGMENTs
https://en.wikipedia.org/wiki/Cyclic_nucleotide–gated_ion_channel
A CNG channel consists of four subunits around a central pore. Each protein subunit consists 6 transmembrane segments (S1-S6), a P-loop, intracellular amino terminal region, and carboxy terminal region. The P-loop and S6 segments around the pore, which plays a role in ion conduction. There is a cyclic nucleotide binding domain (CNBD) and connection region to the S6 segment in the carboxy terminal. There is a post-CNDB region in the amino terminal.[5]
TETRA IS FOUR
https://en.wikipedia.org/wiki/Asimina_tetramera
Asimina tetramera, commonly known as the four-petal pawpaw, is a species of flowering plant endemic to the state of Florida. It is a small tree or large perennial shrub with one or more main stems. There is a total population count of about 950 plants, all of which are limited to areas in Martin and Palm Beach Counties in Florida.[1] This is a federally listed endangered species of the United States.[2]
FOUR CLASSES
https://en.wikipedia.org/wiki/Beta_hairpin
Beta hairpins are broken into four distinct classes as depicted in the publication's Figure 1. Each class begins with the smallest possible number of loop residues and progressively increases the loop size by removing hydrogen bonds in the beta sheet. The primary hairpin of class 1 is a one-residue loop where the bound residues share two hydrogen bonds. One hydrogen bond is then removed to create a three-residue loop, which is the secondary hairpin of class 1. Singly bound residues are counted in the loop sequence but also signal the end of the loop, thus defining this hairpin as a three-residue loop. This single hydrogen bond is then removed to create the tertiary hairpin; a five-residue loop with doubly bound residues. This pattern continues indefinitely and defines all beta hairpins within the class. Class 2 follows the same pattern beginning with a two-residue loop with terminating residues that share two hydrogen bonds. Class 3 begins with a three-residue, and class 4 with a four-residue. Class 5 does not exist as that primary hairpin is already defined in class 1.
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FOUR ORBITAL GYRI
https://en.wikipedia.org/wiki/Orbital_gyri
The inferior or orbital surface of the frontal lobe is concave, and rests on the orbital plate of the frontal bone. It is divided into four orbital gyri by a well-marked H-shaped orbital sulcus. These are named, from their position, the medial, anterior, lateral, and posterior orbital gyri. The medial orbital gyrus presents a well-marked antero-posterior sulcus, the olfactory sulcus, for the olfactory tract; the portion medial to this is named the straight gyrus, and is continuous with the superior frontal gyrus on the medial surface.
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FOUR NUCLEI
https://en.wikipedia.org/wiki/Vagus_nerve
Nuclei[edit]
The vagus nerve includes axons which emerge from or converge onto four nuclei of the medulla:
The dorsal nucleus of vagus nerve — which sends parasympathetic output to the viscera, especially the intestines
The nucleus ambiguus — which gives rise to the branchial efferent motor fibers of the vagus nerve and preganglionic parasympathetic neurons that innervate the heart
The solitary nucleus — which receives afferent taste information and primary afferents from visceral organs
The spinal trigeminal nucleus — which receives information about deep/crude touch, pain, and temperature of the outer ear, the dura of the posterior cranial fossa and the mucosa of the larynx
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4-region scheme[edit]
https://en.wikipedia.org/wiki/Abdomen#Muscles
FOUR QUADRANT SCHEME ABDOMEN
Main article: Quadrant (abdomen)
Quadrants of the abdomen.
Another way of dividing the abdomen is by using 4 quadrants:
right upper quadrant (RUQ)
left upper quadrant (LUQ)
right lower quadrant (RLQ)
left lower quadrant (LLQ)
THERE ARE FOUR MITOCHONDRIAL COMPLEXES AND LOOK AT THE REPETITIONS OF FOUR WITHIN THE COMPLEXES- FOR INSTANCE COMPLEX 2 CONSISTS OF FOUR PROTEIN SUBUNITS
https://en.wikipedia.org/wiki/Electron_transport_chain
Four membrane-bound complexes have been identified in mitochondria. Each is an extremely complex transmembrane structure that is embedded in the inner membrane. Three of them are proton pumps. The structures are electrically connected by lipid-soluble electron carriers and water-soluble electron carriers. The overall electron transport chain:
NADH+H+ → Complex I → Q → Complex III → cytochrome c → Complex IV → H2O
↑
Complex II
↑
Succinate
Complex I[edit]
In Complex I (NADH:ubiquinone oxidoreductase, NADH-CoQ reductase, or NADH dehydrogenase; EC 1.6.5.3), two electrons are removed from NADH and ultimately transferred to a lipid-soluble carrier, ubiquinone (Q). The reduced product, ubiquinol (QH2), freely diffuses within the membrane, and Complex I translocates four protons (H+) across the membrane, thus producing a proton gradient. Complex I is one of the main sites at which premature electron leakage to oxygen occurs, thus being one of the main sites of production of superoxide.[3]
The pathway of electrons is as follows:
NADH is oxidized to NAD+, by reducing Flavin mononucleotide to FMNH2 in one two-electron step. FMNH2 is then oxidized in two one-electron steps, through a semiquinone intermediate. Each electron thus transfers from the FMNH2 to an Fe-S cluster, from the Fe-S cluster to ubiquinone (Q). Transfer of the first electron results in the free-radical (semiquinone) form of Q, and transfer of the second electron reduces the semiquinone form to the ubiquinol form, QH2. During this process, four protons are translocated from the mitochondrial matrix to the intermembrane space. [4] As the electrons become continuously oxidized and reduced throughout the complex an electron current is produced along the 180 Angstrom width of the complex within the membrane. This current powers the active transport of four protons to the intermembrane space per two electrons from NADH.[5]
Complex II[edit]
In Complex II (succinate dehydrogenase or succinate-CoQ reductase; EC 1.3.5.1) additional electrons are delivered into the quinone pool (Q) originating from succinate and transferred (via flavin adenine dinucleotide (FAD)) to Q. Complex II consists of four protein subunits: succinate dehydrogenase, (SDHA); succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial, (SDHB); succinate dehydrogenase complex subunit C, (SDHC) and succinate dehydrogenase complex, subunit D, (SDHD). Other electron donors (e.g., fatty acids and glycerol 3-phosphate) also direct electrons into Q (via FAD). Complex 2 is a parallel electron transport pathway to complex 1, but unlike complex 1, no protons are transported to the intermembrane space in this pathway. Therefore, the pathway through complex 2 contributes less energy to the overall electron transport chain process.
Complex III[edit]
In Complex III (cytochrome bc1 complex or CoQH2-cytochrome c reductase; EC 1.10.2.2), the Q-cycle contributes to the proton gradient by an asymmetric absorption/release of protons. Two electrons are removed from QH2 at the QO site and sequentially transferred to two molecules of cytochrome c, a water-soluble electron carrier located within the intermembrane space. The two other electrons sequentially pass across the protein to the Qi site where the quinone part of ubiquinone is reduced to quinol. A proton gradient is formed by one quinol (2H+2e-) oxidations at the Qo site to form one quinone (2H+2e-) at the Qi site. (in total four protons are translocated: two protons reduce quinone to quinol and two protons are released from two ubiquinol molecules).
QH2 + 2 cytochrome c (FeIII) + 2 H+in → Q + 2 cytochrome c (FeII) + 4 H+out
When electron transfer is reduced (by a high membrane potential or respiratory inhibitors such as antimycin A), Complex III may leak electrons to molecular oxygen, resulting in superoxide formation.
Complex IV[edit]
In Complex IV (cytochrome c oxidase; EC 1.9.3.1), sometimes called cytochrome AA3, four electrons are removed from four molecules of cytochrome c and transferred to molecular oxygen (O2), producing two molecules of water. At the same time, eight protons are removed from the mitochondrial matrix (although only four are translocated across the membrane), contributing to the proton gradient. The activity of cytochrome c oxidase is inhibited by cyanide.
https://en.wikipedia.org/wiki/Electron_transport_chain
quad
https://en.wikipedia.org/wiki/Marsilea
Marsilea is a genus of approximately 65 species of aquatic ferns of the family Marsileaceae. The name honours Italian naturalist Luigi Ferdinando Marsigli (1656–1730).[3]
These small plants are of unusual appearance and do not resemble common ferns. Common names include water clover and four-leaf clover because the long-stalked leaves have four clover-like lobes and are either held above water or submerged.
FOUR HAIR CELLS
https://en.wikipedia.org/wiki/Salvinia_effect
S. minima and S. natans have four free standing hairs connected at a single base. The Giant Salvinia (S. molesta), as well as S. auriculata, and other closely related species, display the most complex hairs: four hairs grow on a shared shaft; they are connected at their tips
The egg-beater hairs of Salvinia molesta and closely related species (e. g. Salvinia auriculata) show an additional remarkable property. The four cells at the tip of each hair (the anchor cells),[2] as opposed to the rest of the hair, are free of wax and therefore hydrophilic; in effect, wettable islands surrounded by a super-hydrophobic surface. This chemical heterogeneity,[4] the Salvinia paradox, enables a pinning of the air water interface to the plant and increases the pressure and longtime stability of the air layer.[4][6]
When submerged under water, no water can penetrate the room between the hairs due to the hydrophobic character of the surfaces. However, the water is pinned to the tip of each hair by the four wax free (hydrophilic) end cells. This fixation results in a stabilization of the air layer under water. The principle is shown in the figure.
Giant Salvinia (S. molesta) at different magnifications; in the SEM picture d) the water repelling wax crystals and the four hydrophilic wax free anchor cells at the hair tips are visible.
FOUR GROUPS FOUR MICROSPERES- TETRAD IS FOUR
https://en.wikipedia.org/wiki/Pollen
In angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of sporogenous cells form within the anther. The fertile sporogenous cells are surrounded by layers of sterile cells that grow into the wall of the pollen sac. Some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells.
In a process called microsporogenesis, four haploid microspores are produced from each diploid sporogenous cell (microsporocyte, pollen mother cell or meiocyte), after meiotic division. After the formation of the four microspores, which are contained by callose walls, the development of the pollen grain walls begins.
The orientation of furrows (relative to the original tetrad of microspores) classifies the pollen as sulcate or colpate. Sulcate pollen has a furrow across the middle of what was the outer face when the pollen grain was in its tetrad.[
ONLY ONE OF FOUR MEGASPORES IS FUNCITONAL IT IS LIKE OOGENESIS IN HUMANS WHERE ONLY ONE OF FOUR OVUMS ARE FUNCTIONAL- AND IN SPERMATOGENESSIS IN MEN FOUR SPERM ARE MADE
https://en.wikipedia.org/wiki/Megaspore_mother_cell
A megaspore mother cell, or megasporocyte, is a diploid cell in plants in which meiosis will occur, resulting in the production of four haploid megaspores. At least one of the spores develop into haploid female gametophytes (megagametophytes).[1] The megaspore mother cell arises within the megasporangium tissue.
In gymnosperms and most flowering plants, only one of the four megaspores is functional at maturity, and the other three soon degenerate
https://en.wikipedia.org/wiki/Tetraloop
Tetraloops are a type of four-base hairpin loop motifs in RNA secondary structure that cap many double helices.[2] There are many variants of the tetraloop, the published ones include ANYA,[3][4] CUYG,[5] GNRA,[6] UMAC[7] and UNCG.[8]
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FRONTAL GYRUS FOUR REGIONS FOUR GYRI
https://en.wikipedia.org/wiki/Frontal_gyrus
The frontal gyrus is the gyrus of the frontal lobe in the brain. It is described as having four regions that are also termed gyri. These regions are the inferior frontal gyrus, the medial frontal gyrus, the middle frontal gyrus, and the superior frontal gyrus. The inferior frontal gyrus includes Broca's area.
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HORSES FOUR NATURAL GAITS I TALKED ABOUT THE FOUR TYPES OF HORSES ALL OF THAT
https://en.wikipedia.org/wiki/Terrestrial_locomotion
Animals will use different gaits for different speeds, terrain, and situations. For example, horses show four natural gaits, the slowest horse gait is the walk, then there are three faster gaits which, from slowest to fastest, are the trot, the canter, and the gallop. Animals may also have unusual gaits that are used occasionally, such as for moving sideways or backwards. For example, the main human gaits are bipedal walking and running, but they employ many other gaits occasionally, including a four-legged crawl in tight spaces.
THE FOUR LOCULES MAKE A QUADRANT- FOUR MICROSPORANGIA
https://en.wikipedia.org/wiki/Stamen
https://en.wikipedia.org/wiki/File:Antera_Lilium.jpg
A typical anther contains four microsporangia. The microsporangia form sacs or pockets (locules) in the anther (anther sacs or pollen sacs). The two separate locules on each side of an anther may fuse into a single locule.
Cross section of a Lilium stamen, with four locules surrounded by the tapetum
https://en.wikipedia.org/wiki/Apomixis
Eragrostis–Panicum types: Two mitotic division give a 4-nucleate megagametophyte, with cell walls to form either three or four cells.
FOUR STAGES OF SEED DEVELOPMENT
https://en.wikipedia.org/wiki/Germination
Precocious germination[edit]
When a seed germinates without undergoing all four stages of seed development, i.e., globular, heart shape, torpedo shape, and cotyledonary stage, it is known as precocious germination.
FOUR PAIRS OF SPORES
https://en.wikipedia.org/wiki/Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes (Ascomycota).
Typically, a single ascus will contain eight ascospores. The eight spores are produced by meiosis followed by a mitotic division. Two meiotic divisions turn the original diploid zygote nucleus into four haploid ones. That is, the single original diploid cell from which the whole process begins contains two complete sets of chromosomes. In preparation for meiosis, all the DNA of both sets is duplicated, to make a total of four sets. The nucleus that contains the four sets divides twice, separating into four new nuclei – each of which has one complete set of chromosomes. Following this process, each of the four new nuclei duplicates its DNA and undergoes a division by mitosis. As a result, the ascus will contain four pairs of spores.
The Fungi Saccharomyces produces ascospores when grown on V-8 medium, acetate ascospore agar, or Gorodkowa medium. These ascospores are globose and located in asci. Each ascus contains one to four ascospores. The asci do not rupture at maturity. Ascospores are stained with Kinyoun stain and ascospore stain. When stained with Gram stain, ascospores are gram-negative while vegetative cells are gram-positive.
The fission yeast Schizosaccharomyces pombe is a single-celled haploid organism that reproduces asexually by mitosis and fission. However, exposure to the DNA damaging agent hydrogen peroxide induces pair-wise mating of haploid cells of opposite mating type to form transient diploid cells that then undergo meiosis to form asci, each with four ascospores.[1] The production of viable ascospores depends on successful recombinational repair during meiosis.[2] When this repair is defective a quality control mechanism prevents germination of damaged ascospores. These findings suggest that mating followed by meiosis is an adaptation for repairing DNA damage in the parental haploid cells in order to allow production of viable progeny ascospores.
LOOK LIKE QUADRANTS
https://en.wikipedia.org/wiki/Marsileaceae
The group is commonly known as the "pepperwort family" or as the "water-clover family" because the leaves of the genus Marsilea superficially resemble the leaves of a four-leaf clover (a flowering plant).
Marsilea can be distinguished from the other two genera by the presence of four leaflets on each leaf.
The leaves are the most easily observed characteristic for the Marsileaceae; they have a long slender leaf stalk ending in zero, two, or four (occasionally six) leaflets. The number of leaflets differs among the three genera and can therefore be used for identification.[4] In Pilularia, the leaves are narrowly cylindrical and taper to a point. Leaves of Regnellidium bear two broad leaflets, while leaves of Marsilea bear four leaflets at the tip. The four leaflets on the leaf of Marsilea are not borne equally. Instead, they are borne in pairs with one pair of leaflets attached slightly higher than the other.[11] Thus in the developing leaf, the leaflets are folded more like the wings of a butterfly than like the leaflets of a clover.
TWO SUBFAMILIES EACH WITH FOUR GENERA
https://en.wikipedia.org/wiki/Notonectidae
Notonectidae are similar in appearance to Corixidae (common names 'Water boatman' in the US, 'Lesser water boatman' in the UK), but can be distinguished by their larger size (up to 20 mm), dorsal-ventral coloration, front legs, and predatory behavior. Their dorsum is convex, lightly colored without cross striations. Their front tarsi are not scoop-shaped and their hind legs are fringed for swimming. There are two subfamilies, Notonectinae and Anisopinae, each containing four genera.
Fourth different
FOUR HAPLOID CELLS
https://en.wikipedia.org/wiki/Flowering_plant
A diploid cell (megaspore mother cell) in the ovule undergoes meiosis (involving two successive cell divisions) to produce four cells (megaspores or female gametes) with haploid nuclei.[48] One of these four cells (megaspore) then undergoes three successive mitotic divisions to produce an immature embryo sac (megagametocyte) with eight haploid nuclei
Pollen is also produced by meiosis in the male anther (microsporangium). During meiosis, a diploid microspore mother cell undergoes two successive meiotic divisions to produce 4 haploid cells (microspores or male gametes).
HUSK SPLITS INTO FOUR SECTIONS
https://en.wikipedia.org/wiki/Pecan
The outer husk is 3–4 mm (0.12–0.16 in) thick, starts out green and turns brown at maturity, at which time it splits off in four sections to release the thin-shelled nut
CATS HAVE FOUR SETS OF WHISKERS
https://en.wikipedia.org/wiki/Cat_senses
A cat has about twenty-four movable vibrissae ("whiskers"), in four sets on each upper lip on either side of its nose (some cats may have more). There are also a few on each cheek, tufts over the eyes, bristles on the chin, the cat's inner "wrists", and at the back of the legs.[14] The Sphynx (a nearly hairless breed) may have full length, short, or no whiskers at all.
FOUR MICROSPERES FOUR POLLEN SACS FOUR WALL LAYERS
A microsporangium (plural microsporangia) is a sporangium that produces spores that give rise to male gametophytes. Microsporangia are notable in spikemosses, and a minority of ferns. In gymnosperms and angiosperms (flowering plants), the microsporangia produce the microsporocyte, also known as the microspore mother cell, which then creates four microspores through meiosis. The microspores divide through mitosis to create pollen grains. The term is only applicable to plants that exhibit heterospory and is not used for bryophytes.
https://en.wikipedia.org/wiki/Microsporangia
Development of pollen sacs[edit]
A very young anther consists of actively dividing meristematic cells surrounded by a layer of epidermis. It then becomes two-lobed. Each anther lobe develops two pollen sacs. Thus, a two-lobed anther develops four pollen sacs situated at four corners of the anther. Development of pollen sacs begins with the differentiation of archesporial cells in the hypodermal region below epidermis at four corners of the young anther. The archesporial cells divide by periclinal division to give a subepidermal primary parietal layer and a primary sporogenous layer. The cells of the primary parietal layer divide by successive periclinal and anticlinal divisions to form concentric layers of pollen sac wall. The wall layers from periphery to centre consist of:
1. A single layer of epidermis between, which becomes stretched and shrivels off at maturity
2. A single layer of endothecium. The cells of endothecium possess fibrous thickenings. They remain thin-walled and constitute stomium (line of dehiscence) in the shallow groove in between the two microsporangia of the anther lobe
3. One to three middle layers. Cells of these layers generally disintegrate in the mature anther
4. A single layer of tapetum. The tapetal cells may be uni-, bi- or multinucleate and possess dense cytoplasm. The cells of the primary sporogenous layer divide further and give rise to diploid sporogenous tissue.
https://en.wikipedia.org/wiki/File:Gray5.svg
DIAGRAM OOGENESIS IN HUMANS- FOUR OVUM ARE MADE- ONLY ONE USED- THE FOURTH IS DIFFERENT
SPERMATOGENESIS CREATES FOUR SPERM
Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa.[1]
https://en.wikipedia.org/wiki/Spermatogenesis
https://en.wikipedia.org/wiki/File:Figure_28_01_04.jpg
QUADRANT
NUCLEAR FUSION HAPPENS THROUGH FOUR PARTICLES- AND THERE ARE FOUR IMPORTANT REACTIONS
https://en.wikipedia.org/wiki/Nuclear_fusion
The net result is the fusion of four protons into one alpha particle, with the release of two positrons, two neutrinos (which changes two of the protons into neutrons), and energy.
FOUR ALPHA GLOBIN GENES- TETRAMERS
https://en.wikipedia.org/wiki/Alpha-thalassemia
Alpha-thalassemia (α-thalassemia, α-thalassaemia) is a form of thalassemia involving the genes HBA1[1] and HBA2.[2] Alpha-thalassemia is due to impaired production of alpha chains from 1,2,3, or all 4 of the alpha globin genes, leading to a relative excess of beta globin chains. The degree of impairment is based on which clinical phenotype is present (how many genes are affected).[3][4]
The mechanism sees that α thalassemias results in decreased alpha-globin production, therefore fewer alpha-globin chains are produced, resulting in an excess of β chains in adults and excess γ chains in newborns. The excess β chains form unstable tetramers called hemoglobin H or HbH of four beta chains. The excess γ chains form tetramers which are poor carriers of O2 since their affinity for O2 is too high, so it is not dissociated in the periphery. Homozygote α0 thalassaemias, where numerous γ4 but no α-globins occur at all (referred to as Hb Barts), often result in death soon after birth.[3][5][8]
Two genetic loci exist for α globin, thus four genes are in diploid cells. Two genes are maternal and two genes are paternal in origin. The severity of the α-thalassemias is correlated with the number of affected α-globin; genes: the greater, the more severe will be the manifestations of the disease. When noting the genotype, an "α" indicates a functional alpha chain.[4][5][8]
Four This is known as alpha thalassemia major; these fetuses are edematous, have little circulating hemoglobin, and the hemoglobin that is present is all tetrameric γ chains. When all four alleles are affected, the fetus likely will not survive gestation without in utero intervention; most infants with alpha-thalassemia major are stillborn with hydrops fetalis. Fetuses treated with intrauterine transfusions throughout pregnancy starting at an early gestational age can survive to birth with acceptable morbidity. After birth, the treatment options include bone marrow transplantation or continued chronic transfusions.[10]
IT SAYS THAT "IT IS NOT YET EXPLAINED WHY ONLY FOUR HIV GROUPS SPREAD CONSIDERABLY IN HUMAN POPULATIONS"--- SCIENTISTS THINK THERE SHOULD BE MORE THEY DO NOT HAVE AN EXPLANATION- I HAVE AN EXPLANATIN- THE QUADRANT MODEL
https://en.wikipedia.org/wiki/History_of_HIV/AIDS
It is not yet explained why only four HIV groups (HIV-1 groups M and O, and HIV-2 groups A and B) spread considerably in human populations, despite bushmeat practices being widespread in Central and West Africa,[11] and the resulting human SIV infections being common.[24]
ALL SCIENTISTS AGREE THAT THERE WAS A SIMULTANEOUS EMERGENCE OF FOUR HIV GROUPS IN THE LATE 19TH CENTURY AND THIS WAS THE BEGINNING OF HIV- THEY DO NOT KNOW WHY IT WAS FOUR- IT'S BECAUSE OF THE QUADRANT MODEL
https://en.wikipedia.org/wiki/History_of_HIV/AIDS
Origin and epidemic emergence[edit]
Several of the theories of HIV origin accept the established knowledge of the HIV/SIV phylogenetic relationships, and also accept that bushmeat practice was the most likely cause of the initial transfer to humans. All of them propose that the simultaneous epidemic emergences of four HIV groups in the late 19th-early 20th century, and the lack of previous known emergences, are explained by new factor(s) that appeared in the relevant African regions in that timeframe.
The Chinese government's "Four Free and One Care" policy for AIDS control entails:
https://en.wikipedia.org/wiki/HIV/AIDS_in_China
Free antiretroviral drugs to AIDS patients who are rural residents or people without insurance living in urban areas.
Free voluntary counselling and testing.
Free drugs to HIV-infected pregnant women to prevent mother-to-child transmission, and HIV testing of newborn babies.
Free schooling for AIDS orphans.
Care and economic assistance to the households of people living with HIV/AIDS.
FOUR STAGES
https://en.wikipedia.org/wiki/Cancer_staging
Colon cancer: originally consisted of four stages: A, B, C, and D (the Dukes staging system). More recently, colon cancer staging is indicated either by the original A-D stages or by TNM.[5]
SYPHILIS FOUR STAGES
https://en.wikipedia.org/wiki/Syphilis
Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary,[5] and may also occur congenitally.[13] It was referred to as "the great imitator" by Sir William Osler due to its varied presentations.[5][14]
THERE ARE FOUR CORE HISTONES- TETRAMER ----
THE FOUR DIMERS CREATE AN OCTAMER
https://en.wikipedia.org/wiki/Histone
The resulting four distinct dimers then come together to form one octameric nucleosome core, approximately 63 Angstroms in diameter (a solenoid (DNA)-like particle)
The nucleosome core is formed of two H2A-H2B dimers and a H3-H4 tetramer, forming two nearly symmetrical halves by tertiary structure (C2 symmetry; one macromolecule is the mirror image of the other).[8] The H2A-H2B dimers and H3-H4 tetramer also show pseudodyad symmetry.
The 4 'core' histones (H2A, H2B, H3 and H4) are relatively similar in structure and are highly conserved through evolution, all featuring a 'helix turn helix turn helix' motif (which allows the easy dimerisation). They also share the feature of long 'tails' on one end of the amino acid structure - this being the location of post-translational modification (see below).
https://en.wikipedia.org/wiki/List_of_fictional_diseases
MacGregor's Syndrome Batman & Robin A four-stage disease that Mr. Freeze's wife, Nora, was suffering from and was placed in cryogenic stasis for. The film also revealed that Batman's butler, Alfred Pennyworth, was also suffering from Stage-1 MacGregor's. Mr. Freeze successfully created the antidote for Stage-1 of the disease, and gave some of it to Batman as an apology for thinking that Batman killed Nora (which was actually a lie fabricated by Poison Ivy).
EXISTENCE OF FOURTH GROUP DIFFERENT
https://en.wikipedia.org/wiki/HIV
Three groups of HIV-1 have been identified on the basis of differences in the envelope (env) region: M, N, and O.[91] Group M is the most prevalent and is subdivided into eight subtypes (or clades), based on the whole genome, which are geographically distinct.[92] The most prevalent are subtypes B (found mainly in North America and Europe), A and D (found mainly in Africa), and C (found mainly in Africa and Asia); these subtypes form branches in the phylogenetic tree representing the lineage of the M group of HIV-1. Coinfection with distinct subtypes gives rise to circulating recombinant forms (CRFs). In 2000, the last year in which an analysis of global subtype prevalence was made, 47.2% of infections worldwide were of subtype C, 26.7% were of subtype A/CRF02_AG, 12.3% were of subtype B, 5.3% were of subtype D, 3.2% were of CRF_AE, and the remaining 5.3% were composed of other subtypes and CRFs.[93] Most HIV-1 research is focused on subtype B; few laboratories focus on the other subtypes.[94] The existence of a fourth group, "P", has been hypothesised based on a virus isolated in 2009.[95] The strain is apparently derived from gorilla SIV (SIVgor), first isolated from western lowland gorillas in 2006.[95]
FOUR GROUPS OF HIV THE FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Subtypes_of_HIV
HIV-1 is the most common and pathogenic strain of the virus. Scientists divide HIV-1 into a major group (Group M) and two or more minor groups, namely Group N, O and possibly a group P. Each group is believed to represent an independent transmission of SIV into humans (but subtypes within a group are not).[2] A total of 39 ORFs are found in all six possible reading frames (RFs) of HIV-1 complete genome sequence,[3] but only a few of them are functional.
Group M[edit]
With 'M' for "major", this is by far the most common type of HIV, with more than 90% of HIV/AIDS cases deriving from infection with HIV-1 group M. The M group is subdivided further into clades, called subtypes, that are also given a letter. There are also "circulating recombinant forms" or CRFs derived from recombination between viruses of different subtypes which are each given a number. CRF12_BF, for example, is a recombination between subtypes B and F.
Subtype A is common in West Africa.[4]
Subtype B is the dominant form in Europe, the Americas, Japan, and Australia.[5]
Subtype C is the dominant form in Southern Africa, Eastern Africa, India, Nepal, and parts of China.[5]
Subtype D is generally only seen in Eastern and central Africa.[5]
Subtype E is found in Southeast Asia which is the dominant form for heterosexuals as transmission rate is much higher than most other subtypes.
Subtype F has been found in central Africa, South America and Eastern Europe.[6]
Subtype G (and the CRF02_AG) have been found in Africa and central Europe.[6]
Subtype H is limited to central Africa.[6]
(Subtype I) was originally used to describe a strain that is now accounted for as CRF04_cpx, with the cpx for a "complex" recombination of several subtypes.[citation needed]
Subtype J is primarily found in North, Central and West Africa, and the Caribbean[7]
Subtype K is limited to the Democratic Republic of Congo and Cameroon.[6]
These subtypes are sometimes further split into sub-subtypes such as A1 and A2 or F1 and F2.[citation needed] In 2015, the strain CRF19, a recombinant of subtype A, subtype D and subtype G, with a subtype D protease, was found to be strongly associated with rapid progression to AIDS in Cuba.[8] This is not thought to be a complete or final list, and further types are likely to be found.[9]
HIV-1 subtype prevalence in 2002
Group N[edit]
The 'N' stands for "non-M, non-O". This group was discovered by a Franco-Cameroonia team in 1998, when they identified and isolated the HIV-1 variant strain, YBF380, from a Cameroonian woman who died of AIDS in 1995. When tested, the YBF380 variant reacted with an envelope antigen from SIVcpz rather than with those of Group M or Group O, indicating it was indeed a novel strain of HIV-1.[10] As of 2015, less than 20 Group N infections have been recorded.[11]
Group O[edit]
The O ("Outlier") group is not usually seen outside of West-central Africa. It is reportedly most common in Cameroon, where a 1997 survey found that about 2% of HIV-positive samples were from Group O.[12] The group caused some concern because it could not be detected by early versions of the HIV-1 test kits. More advanced HIV tests have now been developed to detect both Group O and Group N.[13]
Group P[edit]
In 2009, a newly analyzed HIV sequence was reported to have greater similarity to a simian immunodeficiency virus recently discovered in wild gorillas (SIVgor) than to SIVs from chimpanzees (SIVcpz). The virus had been isolated from a Cameroonian woman residing in France who was diagnosed with HIV-1 infection in 2004. The scientists reporting this sequence placed it in a proposed Group P "pending the identification of further human cases".[14][15][16]
TYPHOID FEVER HAS FOUR STAGES
https://en.wikipedia.org/wiki/Typhoid_fever
Classically, the course of untreated typhoid fever is divided into four distinct stages, each lasting about a week. Over the course of these stages, the patient becomes exhausted and emaciated.[15]
Yellow Death 1213 A deadly virus which contaminated the entire planet Earth and certain parts of the Tessa Life Orbital. Humans are killed in short time upon infection, but cloned humans are transformed into killer zombies. When 0916 got a large dosage of the virus he mutated into a yellow, four-armed monster with two retractable spines and tentacles. 1213 however was unaffected by the virus due to a successful Immunization to the virus.
Bhutanitis is a genus of swallowtail butterflies that contains four species.
https://en.wikipedia.org/wiki/Bhutanitis
Species[edit]
Bhutanitis lidderdalii, Bhutan glory
Bhutanitis thaidina, Chinese three tailed swallowtail
Bhutanitis mansfieldi, Mansfield's three-tailed swallowtail
Bhutanitis ludlowi, Ludlow's Bhutan swallowtail
"Four Nights Drunk"[edit]
https://en.wikipedia.org/wiki/Seven_Drunken_Nights
Another, more up-tempo, version of the song, "Four Nights Drunk" relates the same overall story, albeit abbreviated. The four nights follow the same pattern as the first nights of "Seven Drunken Nights", with a horse and boots appearing, followed by a hat, and then skipping to the strange man, again dismissed as a baby. This song was recorded by Steeleye Span on their album Ten Man Mop, or Mr. Reservoir Butler Rides Again. They use a different air for the song, more precisely a reel named "The Primrose Lasses".
FOUR CLASSES OF DRUG AGAINST HIV
https://en.wikipedia.org/wiki/Management_of_HIV/AIDS
Schematic description of the mechanism of the four classes of currently available antiretroviral drugs against HIV
FOUR STAGES
https://en.wikipedia.org/wiki/WHO_Disease_Staging_System_for_HIV_Infection_and_Disease_in_Children
The current staging system for HIV infection in children was developed in 2005 and builds upon the staging system in place since 1987. A child is defined as someone under the age of 15. This staging system also requires the presence of HIV infection: HIV antibody for children aged 18 months or more; virological or p24 antigen positive test if aged under 18 months.
Contents [hide]
1 Clinical Stage 1
2 Clinical Stage 2
3 Clinical Stage 3
4 Clinical Stage 4
FOUR EBOLAVIRUS EFFECT HUMANS
https://en.wikipedia.org/wiki/Ebola_virus_disease
EVD in humans is caused by four viruses of the genus Ebolavirus. The four are Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV) and one simply called Ebola virus (EBOV, formerly Zaire Ebola virus
FOUR EBOLA CASES IN AMERICA
https://en.wikipedia.org/wiki/Ebola_virus_cases_in_the_United_States
In December 2014, Ebola virus cases in the United States occurred due to four laboratory-confirmed cases of Ebola virus disease (commonly known as "Ebola") in the United States.[3] Eleven cases have been reported, including these four cases and seven cases medically evacuated from other countries; the first was reported in September 2014.[4] Nine of the people contracted the disease outside the US and traveled into the country, either as regular airline passengers or as medical evacuees; of those nine, two died. Two people have contracted Ebola in the United States. Both were nurses who treated an Ebola patient; both have recovered.
Fourth case: Craig Spencer[edit]
On October 23, Craig Spencer,[14] a physician who treated Ebola patients in West Africa, tested positive for Ebola at Bellevue Hospital Center after having a 100.3 °F (37.9 °C) fever. Officials said he was hospitalized with fever, nausea, pain, and fatigue.[88] He had flown to New York City from Guinea within the previous ten days,[89] and contacted the city's Department of Health and Doctors without Borders after showing symptoms.[90][91] Spencer traveled to Guinea to treat Ebola victims on September 16 and returned on October 16.[92] Spencer had been self-monitoring for symptoms of the disease, and began to feel sluggish on October 21, but did not show any symptoms for two days.[93] His case was the first to be diagnosed in New York.[94] The city was trying to find people who may have been in contact with Spencer between October 21–23.[14]
FOUR STAGES FOUR GRADES
https://en.wikipedia.org/wiki/Peripheral_artery_disease
Classification[edit]
Peripheral artery occlusive disease is commonly divided in the Fontaine stages, introduced by René Fontaine in 1954 for chronic limb ischemia:[36][40]
Stage I: Asymptomatic, incomplete blood vessel obstruction
Stage II: Mild claudication pain in limb
Stage IIA: Claudication when walking a distance of greater than 200 meters
Stage IIB: Claudication when walking a distance of less than 200 meters
Stage III: Rest pain, mostly in the feet
Stage IV: Necrosis and/or gangrene of the limb
A classification introduced by Robert B. Rutherford in 1986 and revised in 1997 consists of four grades and seven categories:[36][41]
Grade 0, Category 0: Asymptomatic
Grade I, Category 1: Mild claudication
Grade I, Category 2: Moderate claudication
Grade I, Category 3: Severe claudication
Grade II, Category 4: Rest pain
Grade III, Category 5: Minor tissue loss; Ischemic ulceration not exceeding ulcer of the digits of the foot
Grade IV, Category 6: Major tissue loss; Severe ischemic ulcers or frank gangrene
FOUR STAGES
https://en.wikipedia.org/wiki/Colon_cancer_staging#Dukes_classification
Dukes classification[edit]
Micrograph of a colorectal adenocarcinoma metastasis to a lymph node. The cancerous cells are at the top center-left of the image, in glands (circular/ovoid structures) and eosinophilic (bright pink). H&E stain.
In 1932 the British pathologist Cuthbert Dukes (1890-1977) devised a classification system for colorectal cancer.[3] Several different forms of the Dukes classification were developed.[4][5] However, this system has largely been replaced by the more detailed TNM staging system and is no longer recommended for use in clinical practice.[6]
Dukes A: Invasion into but not through the bowel wall
Dukes B: Invasion through the bowel wall penetrating the muscle layer but not involving lymph nodes
Dukes C: Involvement of lymph nodes
Dukes D: Widespread metastases[7]
Astler-Coller classification[edit]
An adaptation by the Americans Astler and Coller in 1954 further divided stages B and C[8]
Stage A: Limited to mucosa
Stage B1: Extending into muscularis propria but not penetrating through it; nodes not involved
Stage B2: Penetrating through muscularis propria; nodes not involved
Stage C1: Extending into muscularis propria but not penetrating through it. Nodes involved
Stage C2: Penetrating through muscularis propria. Nodes involved
Stage D: Distant metastatic spread
The stage gives valuable information for the prognosis and management of the particular cancer.[citation needed]
Full Dukes classification[edit]
Another modification of the original Dukes classification was made in 1935 by Gabriel, Dukes and Bussey.[9] This subdivided stage C. This staging system was noted to be prognostically relevant to rectal and colonic adenocarcinoma.[10] Stage D was added by Turnbull to denote the presence of liver and other distant metastases[11]
Stage A: Limited to muscularis propria; nodes not involved
Stage B: Extending beyond muscularis propria; nodes not involved
Stage C: Nodes involved but highest (apical) node spared
Stage D: Distant metastatic spread
https://en.wikipedia.org/wiki/List_of_fictional_diseases
Monkeynucleosis Hey Arnold! A disease that is caused if a person is touched by a monkey. Helga thinks she had this disease when a monkey trainer's monkey kissed her on the arm. It seems that the disease leads to death (Or, as said, "expiration") There are four symptoms: 1) puffy rash where infected, 2) sweaty palms, 3) loss of appetite, and 4) irritability. On the show, monkeynucleosis is said to have been long debunked by modern science.
FOUR SUBTYPES- FOUR STANDARDS
https://en.wikipedia.org/wiki/Hodgkin%27s_lymphoma
Classical Hodgkin lymphoma (excluding nodular lymphocyte predominant Hodgkin's lymphoma) can be subclassified into four pathologic subtypes based upon Reed–Sternberg cell morphology and the composition of the reactive cell infiltrate seen in the lymph node biopsy specimen (the cell composition around the Reed–Sternberg cell(s)).
The original treatment for Hodgkin's was MOPP. The abbreviation stands for the four drugs Mustargen, Oncovin (also known as Vincristine), Prednisone and Procarbazine (also known as Matulane). The treatment is usually administered in four week cycles, often for six cycles. MSD and VCR are administered intravenously, while procarbazine and prednisone are pills taken orally. MOPP was the first combination chemotherapy brought in that achieved a high success rate. It was developed at the National Cancer Institute in the 1960s by a team that included Vincent DeVita, Jr..
Although no longer the most effective combination, MOPP is still used after relapse or where the patient has certain allergies or lung or heart problems which prevents the use of another regimen.
Currently, the ABVD chemotherapy regimen is the standard treatment of Hodgkin's disease in the US. The abbreviation stands for the four drugs Adriamycin, bleomycin, vinblastine, and dacarbazine. Developed in Italy in the 1970s, the ABVD treatment typically takes between six and eight months, although longer treatments may be required.
FOUR STAGES
https://en.wikipedia.org/wiki/Paget%27s_disease_of_bone
The pathogenesis of Paget's disease is described in 4 stages[17]
Osteoclastic activity
Mixed osteoclastic - osteoblastic activity
Osteoblastic activity
Malignant degeneration
FOUR STAGES
https://en.wikipedia.org/wiki/Ann_Arbor_staging
Ann Arbor staging is the staging system for lymphomas, both in Hodgkin's lymphoma (previously called Hodgkin's disease) and non-Hodgkin lymphoma (abbreviated NHL). It was initially developed for Hodgkin's, but has some use in NHL. It has roughly the same function as TNM staging in solid tumors.
The stage depends on both the place where the malignant tissue is located (as located with biopsy, CT scanning and increasingly positron emission tomography) and on systemic symptoms due to the lymphoma ("B symptoms": night sweats, weight loss of >10% or fevers).
The principal stage is determined by location of the tumor:
Stage I indicates that the cancer is located in a single region, usually one lymph node and the surrounding area. Stage I often will not have outward symptoms.
Stage II indicates that the cancer is located in two separate regions, an affected lymph node or organ and a second affected area, and that both affected areas are confined to one side of the diaphragm—that is, both are above the diaphragm, or both are below the diaphragm.
Stage III indicates that the cancer has spread to both sides of the diaphragm, including one organ or area near the lymph nodes or the spleen.
Stage IV indicates diffuse or disseminated involvement of one or more extralymphatic organs, including any involvement of the liver, bone marrow, or nodular involvement of the lungs.
THERE ARE FOUR PHASES TO A MIGRAINE
https://en.wikipedia.org/wiki/Migraine
There are four possible phases to a migraine, although not all the phases are necessarily experienced:[8]
The prodrome, which occurs hours or days before the headache
The aura, which immediately precedes the headache
The pain phase, also known as headache phase
The postdrome, the effects experienced following the end of a migraine attack
FOUR SUBTYPES- FOUR CARDINAL SYMPTOMS
https://en.wikipedia.org/wiki/Parkinson%27s_disease
The term parkinsonism is used for a motor syndrome whose main symptoms are tremor at rest, stiffness, slowing of movement and postural instability. Parkinsonian syndromes can be divided into four subtypes, according to their origin:
primary or idiopathic
secondary or acquired
hereditary parkinsonism, and
Parkinson plus syndromes or multiple system degeneration.[18]
Four motor symptoms are considered cardinal in PD: tremor, rigidity, slowness of movement, and postural instability.[18]
FOUR STAGES
https://en.wikipedia.org/wiki/Periodontal_pathology
This new classification divided plaque-induced periodontal lesions into four stages, namely, initial lesion, early lesion, established lesion and advanced lesion.
FOUR SUBTYPES AND FOUR STAGES
https://en.wikipedia.org/wiki/Lung_cancer
Four main histological subtypes are recognised, although some cancers may contain a combination of different subtypes,[65] such as adenosquamous carcinoma.[12] Rare subtypes include carcinoid tumors, bronchial gland carcinomas and sarcomatoid carcinomas.[12]
Using the TNM descriptors, a group is assigned, ranging from occult cancer, through stages 0, IA (one-A), IB, IIA, IIB, IIIA, IIIB and IV (four). This stage group assists with the choice of treatment and estimation of prognosis.[73]
FOUR STAGES
https://en.wikipedia.org/wiki/Phases_of_clinical_research
Clinical trials involving new drugs are commonly classified into four phases. Individual trials may encompass more than one phase. A common example of this is combined phase I/II or phase II/III trials. Therefore, it may be easier to think of early phase studies and late phase studies.[1] The drug-development process will normally proceed through all four phases over many years. If the drug successfully passes through Phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population. Phase IV are 'post-approval' studies.
Course: fibres pass obliquely forwards and medially cross dorsum of foot and end in four tendons. The medial part of muscle ends in tendon which crosses the dorsalis pedis artery, inserts into dorsal surface base of PPX of great toe and is termed extensor hallucis brevis. The other three tendons insert into lateral sides of tendon of extensor digitorum longus which insert into the 2nd, 3rd and 4th toes.
FOUR TRANSITION ZONEs
https://en.wikipedia.org/wiki/Enthesis
In a fibrous enthesis, the collagenous tendon or ligament directly attaches to the bone, whereas the fibrocartilaginous interface encompasses four transition zones:
Tendinous area displaying longitudinally oriented fibroblasts and a parallel arrangement of collagen fibres
Fibrocartilaginous region of variable thickness where the structure of the cells changes to chondrocytes
Abrupt transition from cartilaginous to calcified fibrocartilage—often called 'tidemark' or 'blue line'
THERE ARE FOUR CLASSES OF GLUTAMATE RECEPTORS THE FOURTH IS DIFFERENT- THREE MAJOR ONES AND A FOURTH DIFFERENT ONE
https://en.wikipedia.org/wiki/Glutamate_(neurotransmitter)
Chemical receptors for glutamate fall into three major classes, known as AMPA receptors, NMDA receptors, and metabotropic glutamate receptors. Many synapses use multiple types of glutamate receptors. AMPA receptors are ionotropic receptors specialized for fast excitation: in many synapses they produce excitatory electrical responses in their targets a fraction of a millisecond after being stimulated. NMDA receptors are also ionotropic, but they differ from AMPA receptors in being permeable, when activated, to calcium. Their properties make them particularly important for learning and memory. Metabotropic receptors act through second messenger systems to create slow, sustained effects on their targets. A FOURTH class, known as kainate receptors, are similar in many respects to AMPA receptors, but much less abundant.
Glutamate exerts its effects by binding to and activating cell surface receptors. In mammals, four families of glutamate receptors have been identified, known as AMPA receptors, kainate receptors, NMDA receptors, and metabotropic glutamate receptors. The first three families are ionotropic, meaning that when activated they open membrane channels that allow ions to pass through. The metabotropic family are G protein-coupled receptors, meaning that they exert their effects via a complex second messenger system.
FOUR CATEGORIES
https://en.wikipedia.org/wiki/Receptor_(biochemistry)
The structures of receptors are very diverse and can broadly be classified into the following categories:
Type 1: L (ionotropic receptors)– These receptors are typically the targets of fast neurotransmitters such as acetylcholine (nicotinic) and GABA; and, activation of these receptors results in changes in ion movement across a membrane. They have a heteromeric structure in that each subunit consists of the extracellular ligand-binding domain and a transmembrane domain where the transmembrane domain in turn includes four transmembrane alpha helices. The ligand-binding cavities are located at the interface between the subunits.
Type 2: G protein-coupled receptors (metabotropic) – This is the largest family of receptors and includes the receptors for several hormones and slow transmitters e.g. dopamine, metabotropic glutamate. They are composed of seven transmembrane alpha helices. The loops connecting the alpha helices form extracellular and intracellular domains. The binding-site for larger peptide ligands is usually located in the extracellular domain whereas the binding site for smaller non-peptide ligands is often located between the seven alpha helices and one extracellular loop.[2] The aforementioned receptors are coupled to different intracellular effector systems via G proteins.[3]
Type 3: Kinase-linked and related receptors (see "Receptor tyrosine kinase", and "Enzyme-linked receptor") - They are composed of an extracellular domain containing the ligand binding site and an intracellular domain, often with enzymatic-function, linked by a single transmembrane alpha helix. The insulin receptor is an example.
Type 4: Nuclear receptors – While they are called nuclear receptors, they are actually located in the cytoplasm and migrate to the nucleus after binding with their ligands. They are composed of a C-terminal ligand-binding region, a core DNA-binding domain (DBD) and an N-terminal domain that contains the AF1(activation function 1) region. The core region has two zinc fingers that are responsible for recognizing the DNA sequences specific to this receptor. The N terminus interacts with other cellular transcription factors in a ligand-independent manner; and, depending on these interactions, it can modify the binding/activity of the receptor. Steroid and thyroid-hormone receptors are examples of such receptors.[4]
FOUR TRANSMEMBRANE DOMAINS
https://en.wikipedia.org/wiki/GABAA_receptor
https://en.wikipedia.org/wiki/File:GABAA_receptor_schematic.png
Each subunit comprises four transmembrane domains with both the N- and C-terminus located extracellularly.
Schematic structure of the GABAA receptor. Left: GABAA monomeric subunit imbedded in a lipid bilayer (yellow lines connected to blue spheres). The four transmembrane α-helices (1–4) are depicted as cylinders. The disulfide bond in the N-terminal extracellular domain which is characteristic of the family of cys-loop receptors (which includes the GABAA receptor) is depicted as a yellow line. Right: Five subunits symmetrically arranged about the central chloride anion conduction pore. The extracellular loops are not depicted for the sake of clarity.
FOUR SUBCLASSES
https://en.wikipedia.org/wiki/G_protein–coupled_receptor
Four sub-classes of G-proteins distinguished from each other by sequence homology (Gαs, Gαi/o, Gαq/11, and Gα12/13). Each sub-class of G-protein consists of multiple proteins, each the product of multiple genes and/or splice variations that may imbue them with differences ranging from subtle to distinct with regard to signaling properties, but in general they appear reasonably grouped into four classes. Because the signal transducing properties of the various possible βγ combinations do not appear to radically differ from one another, these classes are defined according to the isoform of their α-subunit.[7]:1163
FOUR FAMILIES
https://en.wikipedia.org/wiki/GTPase
The heterotrimeric G proteins can be classified by sequence homology of the α unit into four families:
Gs family. These G proteins are used in the signal transduction of taste and smell. They always use the activation of adenylate cyclase as the next step in the signal chain. The s stands for stimulation. Their function is permanently activated by the cholera toxin, which is the cause of the fatal effects of infection with Vibrio cholerae.
Gi family. The i stands for inhibition of the adenylate cyclase; another effector molecule for this protein family is phospholipase C. Also, Gt and Gg proteins are summarized under this label due to sequence homologies. Gt proteins, a.k.a. transducin, is used in the light recognition pathway in retina cells. Gg protein occurs in the taste recognition for bitter. Most Gi protein family members can be inhibited by the pertussis toxin of Bordetella pertussis.
Gq family. These proteins usually have phospholipase C as effector protein.
G12 family. These G proteins can be activated by thromboxan receptors and thrombin receptors. Their effector proteins are unknown.
https://en.wikipedia.org/wiki/Opioid_receptor
There are four major subtypes of opioid receptors.[12] OGFr was originally discovered and named as a new opioid receptor zeta (ζ). However it was subsequently found that it shares little sequence similarity with the other opioid receptors, and has quite different function.
THERE ARE FOUR COMPLEMENT RECEPTORS
https://en.wikipedia.org/wiki/Complement_receptor
A complement receptor is a receptor of the complement system, a part of the mediated innate immune system.
All four complement receptors bind to complement component 3 or complement component 4 fragments on pathogen surface, but they are different in functions. Complement receptor (CR) 1, 3, and 4 work as opsonin. On the other hand, CR2 is a kind of B cell co-receptor.
FOUR TYPES
https://en.wikipedia.org/wiki/Protease-activated_receptor
There are 4 known protease-activated receptors or PARs, numbered from one to four.
Protease-activated receptors are a subfamily of related G protein-coupled receptors that are activated by cleavage of part of their extracellular domain. They are highly expressed in platelets, and also on endothelial cells, myocytes and neurons.[1]
FOUR FAMILIES
https://en.wikipedia.org/wiki/Chemokine_receptor
Chemokine receptors are divided into different families, CXC chemokine receptors, CC chemokine receptors, CX3C chemokine receptors and XC chemokine receptors that correspond to the 4 distinct subfamilies of chemokines they bind. Four families of chemokine receptors differ in spacing of cysteine residues near N-terminal of the receptor.[4]
FOUR GROUPS OF CHEMOKINES AND FOUR CYSTEINE RESIDUES
https://en.wikipedia.org/wiki/Chemokine#CC_chemokines
Chemokines have been classified into four main subfamilies: CXC, CC, CX3C and XC. All of these proteins exert their biological effects by interacting with G protein-linked transmembrane receptors called chemokine receptors, that are selectively found on the surfaces of their target cells.[1]
T-lymphocytes: the four key chemokines that are involved in the recruitment of T lymphocytes to the site of inflammation are: CCL2, CCL1, CCL22 and CCL17. CXCR3 expression is induced by T-cell activation and activated T-cells are attracted to inflammation sites where the IFN-y inducible chemokines CXCL9, CXCL10 and CXCL11 are secreted [5].
Proteins are classified into the chemokine family based on their structural characteristics, not just their ability to attract cells. All chemokines are small, with a molecular mass of between 8 and 10 kDa. They are approximately 20-50% identical to each other; that is, they share gene sequence and amino acid sequence homology. They all also possess conserved amino acids that are important for creating their 3-dimensional or tertiary structure, such as (in most cases) four cysteines that interact with each other in pairs to create a Greek key shape that is a characteristic of chemokines. Intramolecular disulfide bonds typically join the first to third, and the second to fourth cysteine residues, numbered as they appear in the protein sequence of the chemokine. Typical chemokine proteins are produced as pro-peptides, beginning with a signal peptide of approximately 20 amino acids that gets cleaved from the active (mature) portion of the molecule during the process of its secretion from the cell. The first two cysteines, in a chemokine, are situated close together near the N-terminal end of the mature protein, with the third cysteine residing in the centre of the molecule and the fourth close to the C-terminal end. A loop of approximately ten amino acids follows the first two cysteines and is known as the N-loop. This is followed by a single-turn helix, called a 310-helix, three β-strands and a C-terminal α-helix. These helices and strands are connected by turns called 30s, 40s and 50s loops; the third and fourth cysteines are located in the 30s and 50s loops.[7]
Members of the chemokine family are divided into four groups depending on the spacing of their first two cysteine residues. Thus the nomenclature for chemokines is, e.g.: CCL1 for the ligand 1 of the CC-family of chemokines, and CCR1 for its respective receptor.
FOUR TYPES AND TETRAPYRROLES
https://en.wikipedia.org/wiki/Phycobilin
There are four types of phycobilins:
Phycoerythrobilin, which is red
Phycourobilin, which is orange
Phycoviolobilin (also known as phycobiliviolin) found in phycoerythrocyanin
Phycocyanobilin (also known as phycobiliverdin), which is blue.
They can be found in different combinations attached to phycobiliproteins to confer specific spectroscopic properties.
Structural relation to other molecules[edit]
In chemical terms, phycobilins consist of an open chain of four pyrrole rings (tetrapyrrole) and are structurally similar to the bile pigment bilirubin, which explains the name. (Bilirubin's conformation is also affected by light, a fact used for the phototherapy of jaundiced newborns.) Phycobilins are also closely related to the chromophores of the light-detecting plant pigment phytochrome, which also consist of an open chain of four pyrroles. Chlorophylls are composed of four pyrroles as well, but there the pyrroles are arranged in a ring and contain a metal atom in the center.
FOUR PYRROLE
https://en.wikipedia.org/wiki/Porphin
Porphin, sometimes spelled porphine, is the parent chemical compound for types of biochemically significant compounds called porphyrins. The chemical formula of porphin is C20H14N4. Porphin is an organic compound that is aromatic and heterocyclic since its chemical structure, shown at right, essentially consists of four pyrrole rings joined together by four methine (=CH—) groups to form a larger macrocycle ring. The compound itself is a solid.
https://en.wikipedia.org/wiki/Bilirubin
Bilirubin consists of an open chain of four pyrrole-like rings (tetrapyrrole). In heme, these four rings are connected into a larger ring, called a porphyrin ring.
Bilirubin can be "conjugated" with a molecule of glucuronic acid which makes it soluble in water (see below). This is an example of glucuronidation.
Bilirubin is very similar to the pigment phycobilin used by certain algae to capture light energy, and to the pigment phytochrome used by plants to sense light. All of these contain an open chain of four pyrrolic rings.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Stercobilin
Stercobilin is a tetrapyrrolic bile pigment and is one end-product of heme catabolism.[1][2] It is the chemical responsible for the brown color of human feces and was originally isolated from feces in 1932. Stercobilin (and related urobilin) can be used as a marker for biochemical identification of fecal pollution levels in rivers.[3]
TETRA IS FOUR
https://en.wikipedia.org/wiki/Urobilin
Urobilin or urochrome is the chemical primarily responsible for the yellow color of urine. It is a linear tetrapyrrole compound that, along with the related compound urobilinogen, are degradation products of the cyclic tetrapyrrole heme.
TETRA IS FOUR
https://en.wikipedia.org/wiki/Biliverdin
Biliverdin is a green tetrapyrrolic bile pigment, and is a product of heme catabolism.[1][2] It is the pigment responsible for a greenish color sometimes seen in bruises.[2]
TETRA IS FOUR
https://en.wikipedia.org/wiki/Phycoerythrobilin
Phycoerythrobilin is a red phycobilin, i.e. an open tetrapyrrole chromophore found in cyanobacteria and in the chloroplasts of red algae, glaucophytes and some cryptomonads. Phycoerythrobilin is present in the phycobiliprotein phycoerythrin, of which it is the terminal acceptor of energy. The amount of phycoerythrobilin in phycoerythrins varies a lot, depending on the considered organism. In some Rhodophytes and oceanic cyanobacteria, phycoerythrobilin is also present in the phycocyanin, then termed R-Phycocyanin. Like all phycobilins, phycoerythrobilin is covalently linked to these phycobiliproteins by a thioether bond.
THE CALVIN CYCLE BEGINS WITH A FOUR CARBON ACCEPTRO COMPOUND AND ENDS WITH A FOUR CARBON ACCEPTOR COMPOUND
https://en.wikipedia.org/wiki/Citric_acid_cycle
The citric acid cycle begins with the transfer of a two-carbon acetyl group from acetyl-CoA to the four-carbon acceptor compound (oxaloacetate) to form a six-carbon compound (citrate).
At the end of each cycle, the four-carbon oxaloacetate has been regenerated, and the cycle continues.
TETRAMERIC- TETRA IS FOUR
https://en.wikipedia.org/wiki/Avidin
Avidin is a tetrameric biotin-binding protein produced in the oviducts of birds, reptiles and amphibians and deposited in the whites of their eggs. There are also dimeric members of the avidin family found in some bacteria.[1] In chicken egg white, avidin makes up approximately 0.05% of total protein (approximately 180 ug per egg). The tetrameric protein contains four identical subunits (homotetramer), each of which can bind to biotin (Vitamin B7, vitamin H) with a high degree of affinity and specificity. The dissociation constant of avidin is measured to be KD ≈ 10−15 M, making it one of the strongest known non-covalent bonds.[2]
ALSO A TETRAMER
https://en.wikipedia.org/wiki/NeutrAvidin
NeutrAvidin protein is a deglycosylated version of avidin, with a mass of approximately 60,000 daltons. As a result of carbohydrate removal, lectin binding is reduced to undetectable levels, yet biotin binding affinity is retained because the carbohydrate is not necessary for this activity. Avidin has a high pI but NeutrAvidin has a near-neutral pI (pH 6.3), minimizing non-specific interactions with the negatively charged cell surface or with DNA/RNA. Neutravidin still has lysine residues that remain available for derivatization or conjugation.
Like avidin itself, NeutrAvidin is a tetramer with a strong affinity for biotin (Kd = 10−15 M). In biochemical applications, streptavidin, which also binds very tightly to biotin, may be used interchangeably with NeutrAvidin.
Avidin immobilized onto solid supports is also used as purification media to capture biotin-labelled protein or nucleic acid molecules. For example, cell surface proteins can be specifically labelled with membrane-impermeable biotin reagent, then specifically captured using a NeutrAvidin support.
16 POSSIBLE ALDOHEXOSES
https://en.wikipedia.org/wiki/Glucose
Each of the four carbons C-2 through C-5 is a stereocenter, meaning that its four bonds connect to four different substituents. (Carbon C-2, for example, connects to -(C=O)H, -OH, -H, and -(CHOH)4H.) In D-glucose, these four parts must be in a specific three-dimensional arrangement. Namely, when the molecule is drawn in the Fischer projection, the hydroxyls on C-2, C-4, and C-5 must be on the right side, while that on C-3 must be on the left side.
The positions of those four hydroxyls are exactly reversed in the Fischer diagram of L-glucose. D- and L-glucose are two of the 16 possible aldohexoses; the other 14 are allose, altrose, mannose, gulose, idose, galactose, and talose, each with two enantiomers, "D-" and "L-".
FOUR TYPES OF CELLS
https://en.wikipedia.org/wiki/Pancreas
Approximately 3 million cell clusters called pancreatic islets are present in the pancreas.[10] Within these islets are four types of cells which are involved in the regulation of blood glucose levels. Each type of cell secretes a different type of hormone: α alpha cells secrete glucagon (increase glucose in blood), β beta cells secrete insulin (decrease glucose in blood), δ delta cells secrete somatostatin (regulates/stops α and β cells) and PP cells, or γ (gamma) cells, secrete pancreatic polypeptide.[11] These act to control blood glucose through secreting glucagon to increase the levels of glucose, and insulin to decrease it.
https://en.wikipedia.org/wiki/Parathyroid_chief_cell
The four parathyroid glands are embedded in the thyroid gland.
https://en.wikipedia.org/wiki/Gastric_acid
The production of gastric acid in the stomach is tightly regulated by positive regulators and negative feedback mechanisms. Four types of cells are involved in this process: parietal cells, G cells, D cells and enterochromaffine-like cells. Besides this, the endings of the vagus nerve (CN X) and the intramural nervous plexus in the digestive tract influence the secretion significantly.
FOUR SECTIONS STOMACH
https://en.wikipedia.org/wiki/Stomach
In classical anatomy, the human stomach is divided into four sections, beginning at the Gastric cardia,[6] each of which has different cells and functions.
The cardia is where the contents of the oesophagus empty into the stomach. The cardia is defined as the region following the "z-line" of the gastroesophageal junction, the point at which the epithelium changes from stratified squamous to columnar. Near the cardia is the lower oesophageal sphincter.[7]
The fundus (from Latin, "bottom") is formed by the upper curvature of the organ.
The body is the main, central region.
The pylorus (from Greek, "gatekeeper") is the lower section of the organ that facilitates emptying the contents into the small intestine.
LIVER HAS FOUR LOBES
https://en.wikipedia.org/wiki/Liver
he liver is a reddish-brown wedge-shaped organ with four lobes of unequal size and shape
DUODENUM FOUR SECTIONS
https://en.wikipedia.org/wiki/Duodenum
The duodenum is a 25–38 cm C-shaped structure lying adjacent to the stomach. It is divided anatomically into four sections.
THERE IS T3 and T4- T4 IS DIFFERENT- THERE IS ALWAYS THE DYNAMIC BETWEEN THREE AND FOUR- FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Thyroid
The primary function of the thyroid is the production of the iodine-containing thyroid hormones, triiodothyronine (T3) and thyroxine (T4) and the peptide hormone calcitonin.[23] T3 is so named because it contains three atoms of iodine per molecule and T4 contains four atoms of iodine per molecule.[24] The thyroid hormones have a wide range of effects on the human body. These include:
FOUR LAYERS- NOTICE THE THIRD IS MUSCLE AND MOVEMENT THE SECOND IS HOMEOSTASIS AND STRUCTURE- THE FOURTH IS DIFFERENT
Histology[edit]
Main article: Gastrointestinal wall
The four layers that make up the wall of the ileum are consistent with those of the gastrointestinal tract. From the inner to the outer surface, these are:[4]:589
https://en.wikipedia.org/wiki/Ileum
1. A mucous membrane, itself formed by three different layers:
A single layer of tall cells that line the lumen of the organ. The epithelium that forms the innermost part of the mucosa has five distinct types of cells that serve different purposes, these are: enterocytes with microvilli, which digest and absorb nutrients; goblet cells, which secrete mucin, a substance that lubricates the wall of the organ; Paneth cells, most common in the terminal part of the ileum, are only found at the bottom of the intestinal glands and release antimicrobial substances such as alpha defensins and lysozyme;[5] microfold cells, which take up and transport antigens from the lumen to lymphatic cells of the lamina propria; and enteroendocrine cells, which secrete hormones.
An underlying lamina propria composed of loose connective tissue and containing germinal centers and large aggregates of lymphoid tissue called Peyer's patches, which are a distinctive feature of the ileum.[4]:589
A thin layer of smooth muscle called muscularis mucosae.
2. A submucosa formed by dense irregular connective tissue that carries the larger blood vessels and a nervous component called submucosal plexus, which is part of the enteric nervous system.
3. An external muscular layer formed by two layers of smooth muscle arranged in circular bundles in the inner layer and in longitudinal bundles in the outer layer. Between the two layers is the myenteric plexus, formed by nervous tissue and also a part of the enteric nervous system.
4. A serosa composed of mesothelium, a single layer of flat cells with varying quantities of underlying connective and adipose tissue. This layer represents the visceral peritoneum and is continuous with the mesentery.[4]:571
FOUR CORE HISTONES
https://en.wikipedia.org/wiki/Histone_octamer
A histone octamer is the eight protein complex found at the center of a nucleosome core particle. It consists of two copies of each of the four core histone proteins (H2A, H2B, H3 and H4)
Core histones are four proteins called H2A, H2B, H3 and H4 and they are all found in equal parts in the cell. All four of the core histone amino acid sequences contain between 20 to 24% of lysine and arginine and the size or the protein ranges between 11400 and 15400 Daltons, making them relatively small, yet highly positively charged proteins.[6] High content of positively charged amino acids allow them to closely associate with negatively charged DNA. Heterodimers, or histone-only intermediates are formed from histone-fold domains. The formation of histone only-intermediates proceeds when core histones are paired into the interlocked crescent shape quasi-symmetric heterodimer. Each histone fold domain is composed of 3 α-helix regions that are separated by disordered loops. The histone fold domain is responsible for formation of head-to-tail heterodimers of two histones: H2A-H2B and H3-H4. However, H3 and H4 histones first form a heterodimer and then in turn the heterodimer dimerizes to form a tetramer H32-H42.[7] The heterodimer formation is based on the interaction of hydrophobic amino acid residue interactions between the two proteins.[7]
https://en.wikipedia.org/wiki/Tetrode_(biology)
A tetrode is a type of electrode used in neuroscience for electrophysiological recordings. They are generally used to record the extracellular field potentials from nervous tissue, e.g. the brain. Tetrodes are constructed by bundling together four very small electrodes; each wire is generally less than 30 μm in diameter. Tetrodes are used to classify extra-cellular action potentials into sets generated by the individual neurons, as each channel of the tetrode is usually close enough to a cell such that action potentials emitted by that cell are detected on each of the four channels, but because of the spatial distribution of the individual channels, the amplitude of the signal varies across the four channels.
There are a total of four subspecies of B. lidderdalii. These subspecies (with type localities) are:[6]
https://en.wikipedia.org/wiki/Bhutanitis_lidderdalii
B. lidderdalii lidderdalii Atkinson 1873 - (nominate) Buxa, Bhutan
B. lidderdalii spinosa Stichel, 1907 - Sichuan, China
B. lidderdalii ocellatomaculata Igarashi, 1979 - Chiang Mai, northern Thailand
B. lidderdalii nobucoae Morita, 1997 - north Kachin, Myanmar
https://en.wikipedia.org/wiki/Quadrupedalism
Quadrupedalism or pronograde posture is a form of terrestrial locomotion in animals using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet" (from the Latin quattuor for "four" and pes for "foot"). The majority of quadrupeds are vertebrate animals, including mammals such as cattle, dogs and cats, and reptiles such as lizards.
https://en.wikipedia.org/wiki/Large_intestine
The ascending colon is the first of four sections of the large intestine
FOUR PARTS OF COLON
http://www.livescience.com/52026-colon-large-intestine.html
The colon is much wider than the small intestine, but is also much shorter. According to the Cleveland Clinic, the small intestine is 22 feet (6.7 meters) long. The colon is only 6 feet (1.8 m) long.
This 6 feet of dense muscle is divided into four parts: the ascending colon, the transverse colon, the descending colon and the sigmoid colon. Each part represents a location in the broken rectangle shape that the colon makes in the body. The ascending colon is the right arm of the broken rectangle. The beginning of the ascending colon is called the cecum. The cecum is connected to the small intestine and the appendix.
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FOUR COCENTRIC LAYERS- FIRST IS WEIRD- SECOND IS STRUCTURE AND ORDER- THIRD IS MOVEMENT MUSCLE THIRD IS ALWAYS ACTION- FOURTH IS DIFFERENT
https://en.wikipedia.org/wiki/Gastrointestinal_tract
The gastrointestinal tract has a form of general histology with some differences that reflect the specialization in functional anatomy.[18] The GI tract can be divided into four concentric layers in the following order:
Mucosa
Submucosa
Muscular layer
Adventitia or serosa
IN MY BIOLOGY CLASS AT UCSD THE PROFESSOR TAUGHT US THAT THERE WAS FOUR TYPES OF CELL IN THE STOMACH- WIKIPEDIA SAYS THE SAME THING
https://en.wikipedia.org/wiki/Digestive_enzyme
There are four types of cells in the stomach:
Parietal cells: Produce hydrochloric acid and intrinsic factor.
Gastric chief cells: Produce pepsinogen. Chief cells are mainly found in the body of stomach, which is the middle or superior anatomic portion of the stomach.
Mucous neck and pit cells: Produce mucin and bicarbonate to create a "neutral zone" to protect the stomach lining from the acid or irritants in the stomach chyme.
G cells: Produce the hormone gastrin in response to distention of the stomach mucosa or protein, and stimulate parietal cells production of their secretion. G cells are located in the antrum of the stomach, which is the most inferior region of the stomach.
FOUR TYPES OF CELL IN THE STOMACH
http://www.laparoscopic.md/digestion/stomach
Cell types in the stomach that help with digestion
There are four main types of cells for stomach secretions spread all over the inner surface of the stomach:
Mucous cells secrete the alkaline mucous for shielding the epithelium from hydrochloric acid. These are found in the fundic, cardiac, and pyloric region.
Parietal cells, located in the fundic, cardiac, and pyloric region, secrete hydrochloric acid; the acid activates release of pepsin for protein digestion. The acid also kills micro-organisms swallowed with the food.
Chief cells secrete pepsin. These cells are located in the fundic region.
G cells are found in the fundic, pyloric, and gastric region. These secrete gastrin which stimulates the secretion of hydrochloric acid.
TWO TETRAMERS FORM OCTAMER- FOUR CORE HISTONES
https://en.wikipedia.org/wiki/Histone_H4
Histone H4 is a 102 to 135 amino acid protein which shares a structural motif, known as the histone fold, formed from three a-helices connected by two loops. Histone proteins H3 and H4 bind to form a H3-H4 dimer, two of these H3-H4 dimers combine to form a tetramer. This tetramer further combines with two H2a-H2b dimers to form the compact Histone octamer core.[3]
THE FOUR CORE HISTONES- LOOKS LIKE QUADRANT- THE NUCLEOSOME IS THE FOUR CORE HISTONES TIMES TWO
https://en.wikipedia.org/wiki/Nucleosome
https://en.wikipedia.org/wiki/File:Nucleosome_organization.png
The core histone proteins contains a characteristic structural motif termed the "histone fold," which consists of three alpha-helices (α1-3) separated by two loops (L1-2). In solution, the histones form H2A-H2B heterodimers and H3-H4 heterotetramers. Histones dimerise about their long α2 helices in an anti-parallel orientation, and, in the case of H3 and H4, two such dimers form a 4-helix bundle stabilised by extensive H3-H3’ interaction. The H2A/H2B dimer binds onto the H3/H4 tetramer due to interactions between H4 and H2B, which include the formation of a hydrophobic cluster.[13] The histone octamer is formed by a central H3/H4 tetramer sandwiched between two H2A/H2B dimers. Due to the highly basic charge of all four core histones, the histone octamer is stable only in the presence of DNA or very high salt concentrations.
FOUR CLASSES
https://en.wikipedia.org/wiki/Histone_acetylation_and_deacetylation
There are a total of four classes that categorize Histone Deacetylases (HDACs). Class I includes HDACs 1, 2, 3, and 8. Class II is divided into two subgroups, Class IIA and Class IIB. Class IIA includes HDACs 4, 5, 7, and 9 while Class IIB includes HDACs 6 and 10. Class III contains the Sirtuins and Class IV contains only HDAC11.[5][6] Classes of HDAC proteins are divided and grouped together based on the comparison to the sequence homologies of Rpd3, Hos1 and Hos2 for Class I HDACs, HDA1 and Hos3 for the Class II HDACs and the sirtuins for Class III HDACs.[6]
NUCLEOSOMES ARE MADE OF THE FOUR CORE HISTONES
https://en.wikipedia.org/wiki/Histone_methylation
The fundamental unit of chromatin, called a nucleosome, contains DNA wound around a protein octamer. This octamer consists of two copies each of four histone proteins: H2A, H2B, H3, and H4.
FOUR CLASSES
https://en.wikipedia.org/wiki/Histone_deacetylase
HDACs, are classified in four classes depending on sequence homology to the yeast original enzymes and domain organization:[4]
FOUR PHASES CELL CYCLE
https://en.wikipedia.org/wiki/Cell_cycle
https://en.wikipedia.org/wiki/File:Cell_Cycle_2-2.svg
The cell cycle consists of four distinct phases: G1 phase, S phase (synthesis), G2 phase (collectively known as interphase) and M phase (mitosis)
THERE ARE FOUR MAJOR TYPES OF BONE CELLS
Differentiated Bone[edit]
https://en.wikipedia.org/wiki/G0_phase
Of the four major types of bone cells, osteocytes are the most common and also exist in a terminal G0 phase. Osteocytes arise from osteoblasts that are trapped within a self-secreted matrix. While osteocytes also have reduced synthetic activity, they still serve bone functions besides generating structure. Osteocytes work through various mechanosensory mechanisms to assist in the routine turnover over bony matrix.
FOUR SUB STAGES MITOSIS
https://en.wikipedia.org/wiki/G1/S_transition
Following interphase, the cell transitions into mitosis, containing four sub stages: prophase, anaphase, metaphase, and telophase
THERE ARE FOUR DNA DAMAGE CHECKPOINTS
https://en.wikipedia.org/wiki/G1/S_transition
To ensure proper cell division, the cell cycle utilizes numerous checkpoints to monitor cell progression and halt the cycle when processes go awry. These checkpoints include four DNA damage checkpoints, one unreplicated DNA checkpoint at the end of G2, one spindle assembly checkpoint in mitosis, and a chromosome segregation checkpoint during mitosis.[9]
Of the four DNA damage checkpoints, two have an additional process for monitoring DNA damage other than activating p53. Before entry into S phase and during S phase, ATM/R also activates Chk1/2 that inhibits Cdc25A, a protein responsible for activating cyclin-Cdk dimers. Without cyclin dimer activation, the cell cannot transition through the cycle. These two checkpoints have additional processes for regulation because replicating damaged DNA in S phase can be deleterious to the cell and more importantly, the organism.[7]
FOUR GROUPS OF CHECKPOINT PROTEINS
https://en.wikipedia.org/wiki/DNA_repair#DNA_damage_checkpoints
Checkpoint Proteins can be separated into four groups: phosphatidylinositol 3-kinase (PI3K)-like protein kinase, proliferating cell nuclear antigen (PCNA)-like group, two serine/threonine(S/T) kinases and their adaptors. Central to all DNA damage induced checkpoints responses is a pair of large protein kinases belonging to the first group of PI3K-like protein kinases-the ATM (Ataxia telangiectasia mutated) and ATR (Ataxia- and Rad-related) kinases, whose sequence and functions have been well conserved in evolution. All DNA damage response requires either ATM or ATR because they have the ability to bind to the chromosomes at the site of DNA damage, together with accessory proteins that are platforms on which DNA damage response components and DNA repair complexes can be assembled.
https://en.wikipedia.org/wiki/Phosphoinositide_3-kinase
The phosphoinositol-3-kinase family is divided into four different classes: Class I, Class II, Class III, and Class IV. The classifications are based on primary structure, regulation, and in vitro lipid substrate specificity.[9]
THERE ARE FOUR CLASSES OF POTASSIUM CHANNEL- AND THEY ARE TETRAMERIC- TETRA IS FOUR
https://en.wikipedia.org/wiki/Potassium_channel
There are four major classes of potassium channels:
Calcium-activated potassium channel - open in response to the presence of calcium ions or other signalling molecules.
Inwardly rectifying potassium channel - passes current (positive charge) more easily in the inward direction (into the cell).
Tandem pore domain potassium channel - are constitutively open or possess high basal activation, such as the "resting potassium channels" or "leak channels" that set the negative membrane potential of neurons.
Voltage-gated potassium channel - are voltage-gated ion channels that open or close in response to changes in the transmembrane voltage.
Potassium channels have a tetrameric structure in which four identical protein subunits associate to form a fourfold symmetric (C4) complex arranged around a central ion conducting pore (i.e., a homotetramer). Alternatively four related but not identical protein subunits may associate to form heterotetrameric complexes with pseudo C4 symmetry. All potassium channel subunits have a distinctive pore-loop structure that lines the top of the pore and is responsible for potassium selective permeability.
FOUR TRANSMEMBRNE SEGMENTS
https://en.wikipedia.org/wiki/Tandem_pore_domain_potassium_channel
Their name is derived from the fact that the α subunits consist of four transmembrane segments, each containing two pore loops
TETRAMERS
https://en.wikipedia.org/wiki/Voltage-gated_potassium_channel
Typically, vertebrate voltage-gated K+ channels are tetramers of four identical subunits arranged as a ring, each contributing to the wall of the trans-membrane K+ pore. Each subunit is composed of six membrane spanning hydrophobic α-helical sequences. The high resolution crystallographic structure of the rat Kvα1.2/β2 channel has recently been solved (Protein Databank Accession Number 2A79),[7] and then refined in a lipid membrane-like environment (PDB: 2r9r).
TETRAMER
https://en.wikipedia.org/wiki/KcsA_potassium_channel
The structure of KcsA is that of an inverted cone, with a central pore running down the center made up of two transmembrane helices(the outer-helix M1 and the inner-helix M2), which span the lipid bilayer. The channel itself is a tetramer composed of four identical subunits of two arranged so that one M2 helix faces the central pore, while the other M1 helix faces the lipid membrane. The inner helices are tilted by about 25° in relation to the lipid membrane and are slightly kinked, opening up to face the outside of the cell like a flower.[5] These two TM helices are linked by a reentrant loop, dispersed symmetrically around a common axis corresponding to the central pore. The pore region spans approximately 30 amino acid residues and can be divided into three parts: a selectivity filter near the extracellular side, a dilated water-filled cavity at the center, and a closed gate near the cytoplasmic side formed by four packed M2 helices.[5] This architecture is found to be highly conserved in the potassium channel family[9][10] in both eukaryotes and prokaryotes.
https://en.wikipedia.org/wiki/KCNA4
I DESCRIBED DROSOPHILIA ARE SIGNIFICANT BECAUSE THEY ARE MODEL ORGANISMS BECAUSE THEY HAVE ONLY FOUR CHROMOSOMES
Four sequence-related potassium channel genes - shaker, shaw, shab, and shal - have been identified in Drosophila, and each has been shown to have human homolog(s).
FOUR SUBFAMILIES
https://en.wikipedia.org/wiki/KCNC4
The Shaker gene family of Drosophila encodes components of voltage-gated potassium channels and comprises four subfamilies
https://en.wikipedia.org/wiki/Tetrode
A tetrode is a vacuum tube (called valve in British English) having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids and a plate (called anode in British English). There are several varieties of tetrodes, the most common being the screen-grid tube and the beam tetrode. In screen-grid tubes and beam tetrodes, the first grid is the control grid and the second grid is the screen grid.[1] In other tetrodes one of the grids is a control grid, while the other may have a variety of functions.
THERE ARE FOUR FAMILIES- ALSO THERE ARE THREE MAIN SUBUNITS AND THE ARTICLE TALKS ABOUT THE THREE BUT IT LATER MENTIONS THE FOURTH- THE FOURTH IS ALWAYS DIFFERENT
https://en.wikipedia.org/wiki/Epithelial_sodium_channel
The epithelial sodium channel (short: ENaC, also: amiloride-sensitive sodium channel) is a membrane-bound ion-channel that is selectively permeable to Na+ ions and that is assembled as a heterotrimer composed of three homologous subunits α or δ, β, and γ, [2] These subunits are encoded by four genes: SCNN1A, SCNN1B, SCNN1G, and SCNN1D. It is involved primarily in the reabsorption of sodium ions in the collecting ducts of the kidney's nephrons.
δ-subunit[edit]
In addition there is a fourth, so-called δ-subunit, that shares considerable sequence similarity with the α-subunit and can form a functional ion-channel together with the β- and γ-subunits. Such δ-, β-, γ-ENaC appear in pancreas, testes, and ovaries. Their function is yet unknown.
Members of the epithelial Na+ channel (ENaC) family fall into four subfamilies, termed alpha, beta, gamma and delta.[4] The proteins exhibit the same apparent topology, each with two transmembrane (TM)-spanning segments (TMS), separated by a large extracellular loop. In most ENaC proteins studied to date, the extracellular domains are highly conserved and contain numerous cysteine residues, with flanking C-terminal amphipathic TM regions, postulated to contribute to the formation of the hydrophilic pores of the oligomeric channel protein complexes. It is thought that the well-conserved extracellular domains serve as receptors to control the activities of the channels.
FOUR FAMILIES
https://en.wikipedia.org/wiki/Cell_adhesion_molecule
Most of the CAMs belong to four protein families: Ig (immunoglobulin) superfamily (IgSF CAMs), the integrins, the cadherins, and the selectins.
FOUR GROUPS ADHERINS
https://en.wikipedia.org/wiki/Cadherin
There are said to be over 100 different types of cadherins found in vertebrates, which can be classified into four groups: classical, desmosomal, protocadherins, and unconventional.[14][15] This large amount of diversity is accomplished by having multiple cadherin encoding genes combined with alternative RNA splicing mechanisms. Invertebrates contain fewer than 20 types of cadherins.[15]
FOUR TRANSMEMBRANE DOMAINS
https://en.wikipedia.org/wiki/Tetraspanin
Tetraspanins, also referred to as the transmembrane 4 superfamily (TM4SF) proteins, have four transmembrane domains, intracellular N- and C-termini and two extracellular domains, one short (called the small extracellular domain or loop, SED/SEL or EC1) and one longer, typically 100 amino acid residues (the large extracellular domain/loop, LED/LEL or EC2). Although several protein families have four transmembrane domains, tetraspanins are defined by conserved domains listed in the Protein Families database under pfam00335.12.[1] The key features are four or more cysteine residues in the EC2 domain, with two in a highly conserved 'CCG' motif.
PHOSPHATES ARE TETRAHEDRAL AND EXTREMELY IMPORTANT- THERE ARE FOUR FORMS OF AQUEOUS PHOSPHATE
https://en.wikipedia.org/wiki/Phosphate
In biology, adding phosphates to—and removing them from—proteins in cells are both pivotal in the regulation of metabolic processes. Referred to as phosphorylation and dephosphorylation, respectively, they are important ways that energy is stored and released in living systems.
The phosphate ion is a polyatomic ion with the empirical formula PO3−
4 and a molar mass of 94.97 g/mol. It consists of one central phosphorus atom surrounded by four oxygen atoms in a tetrahedral arrangement
Aqueous phosphate exists in four forms. In strongly basic conditions, the phosphate ion (PO3−
4) predominates, whereas in weakly basic conditions, the hydrogen phosphate ion (HPO2−
4) is prevalent. In weakly acidic conditions, the dihydrogen phosphate ion (H
2PO−
4) is most common. In strongly acidic conditions, trihydrogen phosphate (H
3PO
4) is the main form.
https://en.wikipedia.org/wiki/Co-receptor
The CD4 receptor is composed of four concatamerized Ig-like domains and is anchored to the cell membrane by a single transmembrane domain.
https://en.wikipedia.org/wiki/Japanese_striped_snake
Elaphe quadrivirgata, commonly known as the Japanese four-lined ratsnake or the Japanese striped snake (Japanese: shimahebi = striped snake), is a species of non-venomous colubrid snake native to Japan.
FOUR DOMAINS
https://en.wikipedia.org/wiki/ATP-binding_domain_of_ABC_transporters
Most ABC transporters function as a dimer and therefore are constituted of four domains, two ABC modules and two TMDs.
ABC transporters are involved in the export or import of a wide variety of substrates ranging from small ions to macromolecules. The major function of ABC import systems is to provide essential nutrients to bacteria. They are found only in prokaryotes and their four constitutive domains are usually encoded by independent polypeptides (two ABC proteins and two TMD proteins). Prokaryotic importers require additional extracytoplasmic binding proteins (one or more per systems) for function. In contrast, export systems are involved in the extrusion of noxious substances, the export of extracellular toxins and the targeting of membrane components. They are found in all living organisms and in general the TMD is fused to the ABC module in a variety of combinations. Some eukaryotic exporters encode the four domains on the same polypeptide chain.
HERE IS ANOTHER DIAGRAM OF THE FOUR DOMAINS IN THE SODIUM CHANNELS--- WHAT IS INTERESTING IS THE FOURTH DOMAIN IS DIFFERENT- THERE IS a positively charged region between the III and IV domains of sodium channels --- YES THERE ARE OTHER NUMBERS THERE IS SIX SEGMENTS WITHIN EACH OF THE FOUR DOMAINS- BUT THE FOUR IS DOMINANT BECAUSE THE QUADRANT IS THE FORM OF BEING
https://en.wikipedia.org/wiki/Sodium_channel#Alpha_subunits
https://en.wikipedia.org/wiki/File:Sodium-channel.svg
Sodium channels consist of large α subunits that associate with proteins, such as β subunits. An α subunit forms the core of the channel and is functional on its own. When the α subunit protein is expressed by a cell, it is able to form channels that conduct Na+ in a voltage-gated way, even if β subunits or other known modulating proteins are not expressed. When accessory proteins assemble with α subunits, the resulting complex can display altered voltage dependence and cellular localization.
The α-subunit has four repeat domains, labeled I through IV, each containing six membrane-spanning segments, labeled S1 through S6. The highly conserved S4 segment acts as the channel's voltage sensor. The voltage sensitivity of this channel is due to positive amino acids located at every third position.[5] When stimulated by a change in transmembrane voltage, this segment moves toward the extracellular side of the cell membrane, allowing the channel to become permeable to ions. The ions are conducted through a pore, which can be broken into two regions. The more external (i.e., more extracellular) portion of the pore is formed by the "P-loops" (the region between S5 and S6) of the four domains. This region is the most narrow part of the pore and is responsible for its ion selectivity. The inner portion (i.e., more cytoplasmic) of the pore is formed by the combined S5 and S6 segments of the four domains. The region linking domains III and IV is also important for channel function. This region plugs the channel after prolonged activation, inactivating it.
VOLTAGE GATED ION CHANNELS HAVE FOUR DOMAINS- AGAIN EACH OF THE FOUR DOMAINS HAS SIX SEGMENTS BUT THERE ARE FOUR DOMAINS
https://en.wikipedia.org/wiki/Voltage-gated_ion_channel
https://en.wikipedia.org/wiki/File:Ion_channel_in_conformation.png
Conformation of the four homologous domains showing the formation of a central pore
Voltage-gated ion channels are generally composed of several subunits arranged in such a way that there is a central pore through which ions can travel down their electrochemical gradients. The channels tend to be ion-specific, although similarly sized and charged ions may sometimes travel through them. The functionality of voltage-gated ion channels is attributed to its three main discrete units: the voltage sensor, the pore or conducting pathway, and the gate.[3] Na+, K+, and Ca2+ channels are composed of four transmembrane α-subunits arranged around a central pore.[4] The membrane-spanning segments, designated S1-S6, all take the form of alpha helices with specialized functions. The fifth and sixth transmembrane segments (S5 and S6) and pore loop serve the principal role of ion conduction, comprising the gate and pore of the channel, while S1-S4 serve as the voltage-sensing region.[3] The four subunits may be identical, or different from one another. In addition to the four central α-subunits, there are also regulatory β-subunits, with oxidoreductase activity, which are located on the inner surface of the cell membrane and do not cross the membrane, and which are coassembled with the α-subunits in the endoplasmic reticulum.[5]
FOUR GATING PROCESSES
https://en.wikipedia.org/wiki/Gating_(electrophysiology)
The voltage-gated ion channels of the action potential are often described as having four gating processes: activation, deactivation, inactivation, and reactivation (also called 'recovery from inactivation').
FOUR TRANSMEMBRANE DOMAINS
https://en.wikipedia.org/wiki/Nav1.4
In hypokalemic periodic paralysis, arginine residues making up the voltage sensor of Nav1.4 are mutated. The voltage sensor comprises the S4 alpha helix of each of the four transmembrane domains (I-IV) of the protein, and contains basic residues that only allow entry of the positive sodium ions at appropriate membrane voltages by blocking or opening the channel pore.
HERE YOU CAN SEE A DIAGRAM OF A VOLTAGE GATED SODIUM CHANNEL- THERE ARE FOUR DOMAINS- EACH DOMAIN HAS 6 UNITS BUT THERE ARE FOUR- THE FOUR IS DOMINANT- IN A CASE IN ANOTHER PART OF BODY THERE IS SIX DOMAINS- BUT EACH DOMAIN HAS FOUR UNITS- THAT IS BECAUSE THE FOUR ALWAYS REMAINED DOMINANT BECAUSE THE QUADRANT IS THE FORM OF BEING
https://en.wikipedia.org/wiki/Ball_and_chain_inactivation
https://en.wikipedia.org/wiki/File:Sodium_inactivation_mechanims.jpg
Diagram of a voltage-gated sodium channel, showing the important residues for inactivation in red. The domain structure (I – IV) is further subdivided into segments (S1 – 6). The S4 segment is the voltage sensor, which moves out during depolarisation of the cell membrane. This frees up the alanine and asparagine residues with which the IFMT residues in the ball domain bind to. Adapted from Goldin, 2003.[13]
https://en.wikipedia.org/wiki/Ball_and_chain_inactivation
The essential region for inactivation in sodium channels is four amino acid sequence made up of isoleucine, phenylalanine, methionine and threonine (IFMT).[
Hodgkin–Huxley model IS A FAMOUS MODEL AND IT USES FOUR EQUATIONS- AND FOUR STATE VARIABLES LIKE MAXWELL USES FOUR EQUATIONS LIKE THERE ARE THE FOUR KINEMATIC EQUATIONS
https://en.wikipedia.org/wiki/Hodgkin–Huxley_model
Hodgkin–Huxley model
Using a series of voltage clamp experiments and by varying extracellular sodium and potassium concentrations, Hodgkin and Huxley developed a model in which the properties of an excitable cell are described by a set of four ordinary differential equations.[1] Together with the equation for the total current mentioned above, these are:
The Hodgkin–Huxley model can be thought of as a differential equation with four state variables, v(t), m(t), n(t), and h(t), that change with respect to time t. The system is difficult to study because it is a nonlinear system and cannot be solved analytically. However, there are many numeric methods available to analyze the system. Certain properties and general behaviors, such as limit cycles, can be proven to exist.
A simulation of the Hodgkin–Huxley model in phase space, in terms of voltage v(t) and potassium gating variable n(t). The closed curve is known as a limit cycle.
Center manifold[edit]
Because there are four state variables, visualizing the path in phase space can be difficult. Usually two variables are chosen, voltage v(t) and the potassium gating variable n(t), allowing one to visualize the limit cycle. However, one must be careful because this is an ad-hoc method of visualizing the 4-dimensional system. This does not prove the existence of the limit cycle.
SIXTEEN IDENTIFIED GENES- 16 SQUARES QMR
https://en.wikipedia.org/wiki/Voltage-gated_ion_channel
Calcium (Ca2+) channels[edit]
With sixteen different identified genes for human calcium channels, this type of channel differs in function between cell types. Ca2+ channels give rise to action potentials similarly to Na+ channels in some neurons. They also play a role in neurotransmitter release in pre-synaptic nerve endings. In most cells, Ca2+ channels regulate a wide variety of biochemical processes due to their role in controlling intracellular Ca2+ concentrations.[13]
Big Four (Indian snakes)
https://en.wikipedia.org/wiki/Big_Four_(Indian_snakes)
From Wikipedia, the free encyclopedia
For other uses, see Big Four.
These are the four venomous snake species responsible for causing the most human snake bite cases in the Indian Subcontinent (mostly in India). They are referred to as the big four.
Snakes[edit]
The Big Four:[1]
Indian cobra, Naja naja
Common krait, Bungarus caeruleus
Russell's viper, Daboia russelii
Saw-scaled viper, Echis carinatus
https://en.wikipedia.org/wiki/Lipinia_quadrivittata
The Four-striped Lipinia (Lipinia quadrivittata) is a species of skink.
A LONG BLACK CREST OF FOUR FEATHERS
http://www.oiseaux-birds.com/card-changeable-hawk-eagle.html
Nominate race has rufous head and neck, finely streaked with black.
A long black crest of four feathers is often erected on the crown. White chin and throat are streaked with black.
FOUR SERIES OF SPOTS FOUR PARALLEL STRIPES
https://en.wikipedia.org/wiki/Coronella_austriaca
The colour pattern consists of a brown, grey or reddish ground colour[3] with two rows of small, rather indistinct dark spots running down the back towards the tail. In some cases, each pair of spots may be united toward the neck area, forming a series of cross-bars over the back. There is also a very indistinct series of dark spots running along each of the flanks. These four series of spots along the body overlay four parallel, rather shadowy stripes that also run down the back and flanks.[2]
There are four general ways in which birds drink: using gravity itself, sucking, use of the tongue, and deriving water entirely from food.
https://en.wikipedia.org/wiki/Four-striped_ground_squirrel
The four-striped ground squirrel (Lariscus hosei) is a species of rodent in the family Sciuridae. It is endemic to Borneo. Its natural habitat is subtropical or tropical dry forests. It is threatened by habitat loss.
16 SQUARES QMR
https://en.wikipedia.org/wiki/Coral_snake
Coral snakes are a large group of elapid snakes that can be subdivided into two distinct groups, Old World coral snakes and New World coral snakes. There are 16 species of Old World coral snake
FOUR STRIPES
https://en.wikipedia.org/wiki/File:Canadian_warmth.jpg
Wool cloth of one kind or another was traded as far back as the French regime in North America (1534–1765), but HBC point blankets were introduced in 1780 to compete with similar blankets offered by the Montreal-based private traders.[1] The blankets were often produced with a green stripe, red stripe, yellow stripe and indigo stripe on a white background; the four stripe colours were popular and easily produced using good colourfast dyes at that time.[2]
The classic design featuring green stripe, red stripe, yellow stripe and indigo stripe on a white background
FOUR SPECIES
https://en.wikipedia.org/wiki/Phyllostomus
Phyllostomus is a genus of leaf-nosed bat. It contains four described species.
Species[edit]
Genus Phyllostomus - Spear-nosed Bats
Pale Spear-nosed Bat, Phyllostomus discolor
Lesser Spear-nosed Bat, Phyllostomus elongatus
Greater Spear-nosed Bat, Phyllostomus hastatus
Guianan Spear-nosed Bat, Phyllostomus latifolius
Tetradactyly[edit]
https://en.wikipedia.org/wiki/Dactyly
Tetradactyly (from Greek tetra-="four" plus δακτυλος = "finger") is the condition of having four digits on a limb, as in many amphibians, birds, and theropod dinosaurs. Some mammals also exhibit tetradactyly (for example pigs and the hind limbs of dogs and cats). Cartoon characters are commonly drawn with four digits on each hand/foot as it's clearer to see than five.
Syndactyly, as it occurs in birds, is like anisodactyly, except that the third and fourth toes (the outer and middle forward-pointing toes), or three toes, are fused together, as in the belted kingfisher (Megaceryle alcyon). This is characteristic of Coraciiformes (kingfishers, bee-eaters, rollers, and relatives).
Heterodactyly[edit]
Heterodactyly is like zygodactyly, except that digits 3 and 4 point forward and digits 1 and 2 point back. This is found only in trogons.[4]
Pamprodactyly[edit]
Pamprodactyly is an arrangement in which all four toes point forward, outer toes (toe 1 and sometimes 4) often if not regularly reversible. It is a characteristic of swifts (Apodidae) and mousebirds (Coliiformes).
FOUR SUBORDERS
https://en.wikipedia.org/wiki/Chordeumatida#Classification
The Chordeumatida contains approximately 1200 species,[4][5] classified in four suborders and approximately 50 families, although several families contain only one to five genera.[6]
FOUR SUBORDERS
https://en.wikipedia.org/wiki/Polydesmida
The c. 3500 species of Polydesmida are variously classified into four suborders (names ending in "-idea"), and 28 families, the largest (numerically) including Paradoxosomatidae, Xystodesmidae, and Chelodesmidae.[2]
FOUR SUBORDERS IN THE LARGEST ORDER OF MILIPEDE THE POLYSDESMIDAdit me. It's easy.
FOUR FAMILIES
https://en.wikipedia.org/wiki/Polyxenida
Polyxenida is an order of millipedes readily distinguished by a unique body plan consisting of a soft, non-calcified body ornamented with tufts of bristles – traits that have inspired the common names "bristly millipedes" or "pincushion millipedes". There are at least 86 species in four families worldwide, and are the only living members of the subclass Penicillata.
FOUR FAMILIES
https://en.wikipedia.org/wiki/Sphaerotheriida
Sphaerotheriida is divided into four families whose distributions do not overlap: Procyliosomatidae, Zephroniidae, Sphaerotheriidae and Arthrosphaeridae. The most basal family, Procyliosomatidae, lives in Australia and New Zealand.[3][14] The Zephroniidae (synonym Sphaeropoeidae) occurs in southeast Asia from the Himalayas and China south and east to Sulawesi and inhabits some Philippines islands.[3] The family Sphaerotheriidae only occurs in South Africa with isolated populations in Zimbabwe and Malawi (probably introduced).[5] The Arthrosphaeridae are distributed in southern India and Madagascar.[3]