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FOUR LAYERS BLOOD

https://en.wikipedia.org/wiki/Blood

Fåhræus (a Swedish physician who devised the erythrocyte sedimentation rate) suggested that the Ancient Greek system of humorism, wherein the body was thought to contain four distinct bodily fluids (associated with different temperaments), were based upon the observation of blood clotting in a transparent container. When blood is drawn in a glass container and left undisturbed for about an hour, four different layers can be seen. A dark clot forms at the bottom (the "black bile"). Above the clot is a layer of red blood cells (the "blood"). Above this is a whitish layer of white blood cells (the "phlegm"). The top layer is clear yellow serum (the "yellow bile").[33]

 

Human blood[edit]

The ABO blood group system was discovered in the year 1900 by Karl Landsteiner. Jan Janský is credited with the first classification of blood into the four types (A, B, AB, and O) in 1907, which remains in use today. In 1907 the first blood transfusion was performed that used the ABO system to predict compatibility.[34] The first non-direct transfusion was performed on March 27, 1914. The Rhesus factor was discovered in 1937.

FOUR

https://en.wikipedia.org/wiki/Blood_transfusion

Jan Janský also discovered the human blood groups in 1907 which he classified blood into four groups I, II, III, IV. Titled in Czech "Hematologická studie u psychotiků". His nomenclature is still used in Russia and states of the former USSR, in which blood types O, A, B, and AB are respectively designated I, II, III, and IV.

IT IS WAS ARGUED HE DIED AT 256 YEARS OLD------- 256 IS FOUR TO THE FOURTH POWER

https://en.wikipedia.org/wiki/Li_Ching-Yuen

Li Ching-Yuen or Li Ching-Yun (simplified Chinese: 李清云; traditional Chinese: 李清雲; pinyin: Lǐ Qīngyún) (claimed to be born 1677 or 1736 - died 6 May 1933) was a Chinese herbalist, martial artist and tactical advisor, known for his supposed extreme longevity.[4][5] He claimed to be born in 1736, while disputed records suggest 1677. Both claimed lifespans of 197 and 256 years, far exceeding the longest confirmed lifespan of 122 years and 164 days of the French woman Jeanne Calment. His true date of birth was never determined and his claims have been dismissed by gerontologists as a myth.[6]

THE FRUIT IS CROSS SHAPED
https://en.wikipedia.org/wiki/Plagiobothrys_shastensis
The fruit is a cross-shaped nutlet 2 or 3 millimeters wide divided in half by a rough scar.

Tetralogy of Fallot (TOF) is a congenital heart defect that is present at birth.[2] Symptoms include episodes of bluish color to the skin. When affected babies cry or have a bowel movement, they may develop a "tet spell" where they turn very blue, have difficulty breathing, become limp, and occasionally lose consciousness. Other symptoms may include a heart murmur, finger clubbing, and easy tiring upon breastfeeding.[3]

https://en.wikipedia.org/wiki/Tetralogy_of_Fallot

The cause is typically not known. Risk factors include a mother who uses alcohol, has diabetes, is over the age of 40, or gets rubella during pregnancy. It may also be associated with Down syndrome.[4] Classically there are four defects:[2]

 

a ventricular septal defect, a hole between the two ventricles

pulmonary stenosis, narrowing of the exit from the right ventricle

right ventricular hypertrophy, enlargement of the right ventricle

an overriding aorta, which allows blood from both ventricles to enter the aorta

FOUR TYPES

https://en.wikipedia.org/wiki/Canaan_Dog

Rudolphina Menzel, an immigrant to Mandate Palestine from Austria, having studied the desert free living dogs and the variations in appearances, classified these canines into four types: 1) heavy, sheepdog appearance, 2) dingo-like appearance, 3) Border Collie appearance, 4) Greyhound appearance. Menzel concluded that the Canaan dog is a derivative of the Type III pariah — the collie type (referring to the type of farm collie found in the 1930s which was a medium dog of moderate head type more similar to today's Border Collie, not the modern Rough Collie).

PAVLOVS FOUR TYPES

https://en.wikipedia.org/wiki/Ivan_Pavlov

Pavlov extended the definitions of the four temperament types under study at the time: phlegmatic, choleric, sanguine, and melancholic, updating the names to "the strong and impetuous type, the strong equilibrated and quiet type, the strong equilibrated and lively type, and the weak type."

THE MOST SUCCESS IS WITH FOUR BREEDS OF DOGS- FOUR MAINLY GRADUATED

https://en.wikipedia.org/wiki/Service_dog

In a recent study that was done, there was a noticeable amount of successes with mostly 4 breeds of dogs. The four that were mainly graduated and able to become service dogs were Labrador retrievers, golden retrievers, German shepherds, and Labrador/Golden Retriever crosses. In the study, they found that the Labrador/golden retriever crosses and the Labrador retrievers were the most successful to train in a shorter period of time. Whereas German shepherds and Golden retrievers were more successful if they were trained for a longer period of time instead of a 4-month period.[24]

THE FOUR QUADRANTS OF OPERANT CONDITIONING

 

https://ru.pinterest.com/pin/511017888943002720/

quadrant

FOUR LEARNING QUADRANTS PAVLOV

https://nisiandlisi.files.wordpress.com/2015/05/learningquadrant.jpg

https://nisiandlisi.wordpress.com/category/animal-learning-theory/

Now there are actually four learning quadrants that can be used as “consequences” for behaviour so let’s take a look at them. learningquadrantWhen the aim is to change behaviour we can try to decrease the frequency of the behaviour or increase the frequency of the behaviour. To accomplish the goal we can either add a stimulus or remove a stimulus. Here are some common dog training examples of each.

 

Positive Reinforcement to increase the frequency of a behaviour by adding a stimulus a common example is giving a treat to your dog when she sits, which increases the likelihood that she will sit again by adding the food treat.

 

Negative Reinforcement to increase the frequency of a behaviour by removing a stimulus a common example is removing something the dog doesn’t like to get compliance like holding the collar tight on the dog’s throat until the dog sits.

 

Positive Punishment to decrease the frequency of a behaviour by adding a stimulus a common example is if the dog is pulling on leash, the owner pops the leash causing the dog discomfort. Some training tools that are based on positive punishment learning theory are Spray Bottles, Slip Collars (choke chains), Pinch Collars, and Electronic Shock Collars.

 

Negative Punishment to decrease the frequency of a behaviour by removing a stimulus a common example is removing attention or freedom from a dog who is behaving in an unruly manner (like a time out).

 

In force free learning theory, like the training that Lisi and I teach, we rely heavily on Positive Reinforcement and Negative Punishment to motivate dogs to learn and repeat behaviours that we want to see in real life. We have found through experiences with many different dogs that we get the best results, and feel the best about our training methods when we don’t need to use intimidation and force heavy methods to get the behaviours that we want

ROSE HAS FOUR SUBGENERA

https://en.wikipedia.org/wiki/Rose

The genus Rosa is subdivided into four subgenera:

 

Hulthemia (formerly Simplicifoliae, meaning "with single leaves") containing one or two species from southwest Asia, R. persica and Rosa berberifolia which are the only roses without compound leaves or stipules.

Hesperrhodos (from the Greek for "western rose") contains Rosa minutifolia and Rosa stellata, from North America.

Platyrhodon (from the Greek for "flaky rose", referring to flaky bark) with one species from east Asia, Rosa roxburghii (also known as the chestnut rose).

Rosa (the type subgenus, sometimes incorrectly called Eurosa) containing all the other roses. This subgenus is subdivided into 11 sections.

THE FOUR PETAL ROSE

https://en.wikipedia.org/wiki/Rose

The flowers of most species have five petals, with the exception of Rosa sericea, which usually has only four. Each petal is divided into two distinct lobes and is usually white or pink, though in a few species yellow or red. Beneath the petals are five sepals (or in the case of some Rosa sericea, four). These may be long enough to be visible when viewed from above and appear as green points alternating with the rounded petals. There are multiple superior ovaries that develop into achenes.[4] Roses are insect-pollinated in nature.

THERE ARE FOUR FORMAE OF THE FOUR LEAF ROSE

https://en.wikipedia.org/wiki/Rosa_sericea

Rosa sericea, the silky rose,[1] is a species of Rosa native to southwestern China (Guizhou, Sichuan, Xizang, Yunnan), Bhutan, northern India (Sikkim), Nepal and Myanmar; it grows in mountains at altitudes of 2,000-4,400 m.

 

It is a shrub growing to 2 m tall, often very spiny. The leaves are deciduous, 4–8 cm long, with 7–11 leaflets with a serrated margin. The flowers are 2.5–5 cm diameter, white, with (unusually for a rose) only four petals. The hips are red, 8–15 mm diameter, with persistent sepals, and often bristly.

 

There are four formae:

 

Rosa sericea f. sericea.

Rosa sericea f. glandulosa T.T.Yü & T.C.Ku.

Rosa sericea f. glabrescens Franchet.

Rosa sericea f. pteracantha Franchet.

FOUR FORMAE AND FOUR PETALS ROSE

https://en.wikipedia.org/wiki/Rosa_omeiensis

Rosa omeiensis is a species of Rosa native to central and southwestern China in the provinces of Gansu, Guizhou, Hubei, Ningxia, Qinghai, Shaanxi, Sichuan, Xizang, and Yunnan; it grows in mountains at altitudes of 700 to 4,400 m.

 

It is a shrub growing to 4 m tall, often very spiny. The leaves are deciduous, 3–6 cm long, with 5-13 leaflets with a serrated margin. The flowers are 2.5-3.5 cm diameter, white, with (unusually for a rose) only four petals. The hips are red to orange-yellow, 8–15 mm diameter, with persistent sepals, and often bristly.

 

There are four formae:

 

Rosa omeiensis f. omeiensis.

Rosa omeiensis f. glandulosa T.T.Yü & T.C.Ku.

Rosa omeiensis f. paucijuga T.T.Yü & T.C.Ku.

Rosa omeiensis f. pteracantha Rehder & E.H.Wilson.

It is sometimes treated as a subspecies of the closely related species Rosa sericea.

 

Cultivation and uses[edit]

Four basic parts[change | change source]

Flowers have four basic parts, from the outside in they are:

https://simple.wikipedia.org/wiki/Flower

The perianth, the vegetative parts

The calyx: the outermost whorl consisting of units called sepals. These are often green and enclose the rest of the flower in the bud. They may be absent, or they may be petal-like in some species.

The corolla: the petals, usually thin, soft and often colored to attract animals that help pollination.

The reproductive parts

The androecium, the male part, is the stamens

The gynoecium, the female parts,

four petals

https://en.wikipedia.org/wiki/Hesperis_matronalis

The plentiful, fragrant flowers are produced in large, showy, terminal racemes that can be 30+ cm tall and elongate as the flowers of the inflorescence bloom. When stems have both flowers and fruits, the weight sometimes causes the stems to bend. Each flower is large (2 cm across), with four petals. Flower coloration varies, with different shades of lavender and purple most common, but white, pink, and even some flowers with mixed colors exist in cultivated forms. A few different double-flowered varieties also exist.[3] The four petals are clawed and hairless. The flowers have six stamens in two groups, the four closest to the ovary are longer than the two oppositely positioned. Stigmas are two-lobed. The four sepals are erect and form a mock tube around the claws of the petals and are also colored similarly to the petals.[4]

 

Some plants may bloom until August, but warm weather greatly shortens the duration on each flower's blooming. Seeds are produced in thin fruits 5–14 cm long pods, containing two rows of seeds separated by a dimple. The fruit are terete and open by way of glabrous valves, constricted between the seeds like a pea pod. Seeds are oblong, 3–4 mm long and 1–1.5 mm wide.[5]

 

In North America, Hesperis matronalis is often confused with native Phlox species that also have similar large showy flower clusters. They can be distinguished from each other by foliage and flower differences: dame's rocket has alternately arranged leaves and four petals per flower, while phloxes have opposite leaves and five petals.

FOUR PARTS 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 FOURTH IS ALWAYS DIFFERENT

https://simple.wikipedia.org/wiki/Sunflower

Traditionally, several Native American groups planted sunflowers on the north edges of their gardens as a "fourth sister" to the better known three sisters combination of corn, beans, and squash.[9]

https://en.wikipedia.org/wiki/Asteraceae

It is noteworthy that the four subfamilies Asteroideae, Cichorioideae, Carduoideae and Mutisioideae contain 99% of the species diversity of the whole family (approximately 70%, 14%, 11% and 3% respectively).

LOOK AT THE REPETITION OF QUADRANT AND QUARTET- THIS I SALL ALREADY POSTED IN MY OVER 60 QMR BOOKS
https://en.wikipedia.org/wiki/Cleavage_(embryo)
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/…/File:Equal_vs_unequal_cleavage.j…
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).

QUADRANTS QUARTETS

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).

FOUR CELL TYPES

https://en.wikipedia.org/wiki/Cleavage_(embryo)

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]

CHROMOSOMES HAVE A "FOUR ARM STRUCTURE"- THEY ARE QUADRANTS

https://en.wikipedia.org/wiki/File:Chromosome.svg

Compaction of the duplicated chromosomes during cell division (mitosis or meiosis) results either in a four-arm structure (pictured to the right) if the centromere is located in the middle of the chromosome or a two-arm structure if the centromere is located near one of the ends. Chromosomal recombination during meiosis and subsequent sexual reproduction play a significant role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may unexpectedly evade apoptosis, leading to the progression of cancer.

FOUR CELL DIVISIONS OCCUR RESULTING IN A DENSE BALL 16 CELLS- 16 SQUARES QMR

https://en.wikipedia.org/wiki/Embryogenesis

Cell division with no significant growth, producing a cluster of cells that is the same size as the original zygote, is called cleavage. At least four initial cell divisions occur, resulting in a dense ball of at least sixteen cells called the morula. The different cells derived from cleavage, up to the blastula stage, are called blastomeres. Depending mostly on the amount of yolk in the egg, the cleavage can be holoblastic (total) or meroblastic (partial)[1].

https://en.wikipedia.org/wiki/Volvocaceae

16 CELL- 32 CELL- 64 CELL- 128 CELL- ALL QUADRANT NUMBERS

 

The simplest of the Volvocaeans are ordered assemblies of cells, each similar to the related unicellar protist Chlamydomonas and embedded in a gelatinous matrix. In the genus Gonium, for example, each individual organism is a flat plate consisting of 4 to 16 separate cells, each with two flagella. Similarly, the genera Eudorina and Pandorina form hollow spheres, the former consisting of 16 cells, the latter of 32 to 64 cells. In these genera each cell can reproduce a new organism by mitosis.[1]

 

 

Volvox sp.

Other genera of Volvocaceans represent another principle of biological development as each organism develops differented cell types. In Pleodorina and Volvox, most cells are somatic and only a few are reproductive. In Pleodorina californica a colony normally has either 128 or 64 cells, of which those in the anterior region have only a somatic function, while those in the posterior region can reproduce; the ratio being 3:5. In Volvox only very few cells are able to reproduce new individuals, and in some species of Volvox the reproductive cells are derived from cells looking and behaving like somatic cells. In V. carteri, on the other hand, the division of labor is complete with reproductive cells being set aside during cell division, and they never assume somatic functions or develop functional flagella.[1]

FOUR GENERA

https://en.wikipedia.org/wiki/Baculoviridae

Baculoviridae is a family of viruses. Arthropods, lepidoptera, hymenoptera, diptera, and decapoda serve as natural hosts. There are currently 49 species in this family, divided among 4 genera.[1][2]

CONSISTS OF 16, 32, OR 64 CELLS- ALL QUADRANT NUMBERS

https://en.wikipedia.org/wiki/Eudorina

Eudorina is a paraphyletic genus in the volovocine green algae clade.[1] Eudorina colonies consist of 16, 32 or 64 individual cells grouped together. Each individual cell contains flagella which allow the colony to move as a whole when the individual cells beat their flagella together. Description by GM Smith (1920, p 95):[2]

16 32 CELLS QUADRANT NUMBERS- FOR MAMMALS IT IS 16 CELLS IT IS A MORULA- 16 CELLS IS SQUARES OF QUADRANT MODEL- FOR AMPHIBIANS IT IS 128 CELLS WHICH IS A QUADRANT NUMBER

https://en.wikipedia.org/wiki/Blastocoel

A blastocoel (alt. spelling blastocoele, blastocele) is also termed the blastocyst cavity[6] (or cleavage or segmentation cavity) is the name given to the fluid-filled cavity of the blastula (blastocyst) that results from cleavage of the oocyte (ovum) after fertilization.[7][8] It forms during embryogenesis,[8] as what has been termed a "Third Stage" after the single-celled fertilized oocyte (zygote, ovum[9]) has divided into 16-32 cells,[7] via the process of mitosis.[10] It can be described as the first cell cavity formed as the embryo enlarges,[10] the essential precursor for the differentiated, topologically distinct, gastrula[11]

AFTER FOUR DIVISIONS CONSISTS OF 16 BLASTOMERES CALLED MORULA---- 16 SQUARES QUADRANT MODEL

https://en.wikipedia.org/wiki/Zygote

After fertilization, the conceptus travels down the oviduct towards the uterus while continuing to divide[6] mitotically without actually increasing in size, in a process called cleavage.[7] After four divisions, the conceptus consists of 16 blastomeres, and it is known as the morula.[8] Through the processes of compaction, cell division, and blastulation, the conceptus takes the form of the blastocyst by the fifth day of development, just as it approaches the site of implantation.[9] When the blastocyst hatches from the zona pellucida, it can implant in the endometrial lining of the uterus and begin the embryonic stage of development.

eggs are shed from host at 16 cell stage- 16 squares qmr

https://en.wikipedia.org/wiki/Heligmosomoides_polygyrus

This parasite has a direct life cycle with no intermediate hosts. The life cycle takes about 13–15 days to complete.[1][4] Infected mice will pass faeces containing eggs and egg sizes vary between 70–84 micrometres (µm) in length and 37–53 µm in width.[5] Eggs are shed from the host at the 8–16 cell stage and will hatch in the environment, roughly 24 hours after passing through the host.[6] L1 larvae will emerge from the egg and measure between 300–600 µm in length. Three lip-like structures can be seen around a rudimentary mouth. L1 larvae moult to L2 larvae after 2–3 days, entering bacterial-feeding larval stages present in the environment. The L1 stage cuticle will loosen from either end of the larvae but will remain loosely associated with the L2 larvae, becoming an outer sheath up until infection. After 3 days, the L2 partially moults into ensheathed L3, the infective non-feeding stage. Infective larval stages measure between 480–563 µm long.

FOUR GENERA OF HOMINIDAE

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 BONES OF FOOT

https://en.wikipedia.org/wiki/Little_Foot

"Little Foot" (Stw 573) is the nickname given to a nearly complete Australopithecus fossil skeleton found in 1994–1998 in the cave system of Sterkfontein, South Africa. [1] The fossils were found in a limestone formation in Sterkfontein. The nickname "little foot" was given to the fossil in 1995. From the structure of the four ankle bones they were able to ascertain that the owner was able to walk upright. The recovery of the bones proved extremely difficult and tedious, because they are completely embedded in concrete-like rock. It is due to this that the recovery and excavation of the site took around 15 years to complete.[1]

 

The four bones of the ankle had been collected already in 1980 but were undetected between numerous other mammal bones. Only after 1992, on initiative by Phillip Tobias, a large rock was blown up in the cave that contained an unusual accumulation of fossils. The fossils recovered were taken from the cave and scrutinized thoroughly by paleoanthropologist Ronald J. Clarke.[2]

 

In 1994 while searching through museum boxes labelled 'Cercopithecoids' containing fossil fragments, Ronald J. Clarke identified several that were unmistakably hominin. He spotted four left foot bones (the talus, navicular, medial cuneiform and first metatarsal) that were most likely from the same individual.[3] These fragments came from the Silberberg Grotto, a large cavern within the Sterkfontein cave system. They were described as belonging to the genus Australopithecus, and catalogued as Stw 573.[4]

 

In 1995, the first description of the four first discovered foot bones was published. The authors explained that this Australopithecus specimen walked upright but was also able to live in trees with the help of grasping movements. This would be possible due to the still opposable big toe.

AVICENNAS BOOK ON MEDICINE WAS CENTERED AROUND THE QUADRANT MODEL- THESIS ONE WAS CENTERED AROUND THE FOUR CAUSES OF ARISTOTLE THESIS TWO WAS THE FOUR ELEMENTS- THESIS THREE WAS THE FOUR TEMPERAMENTS- HE THEN DIVIDES LIFE INTO FOUR STAGES AND RELATES THEM TO THE FOUR TEMPERAMENTS- THEN HE DISCUSSES THE FOUR HUMOURS

https://en.wikipedia.org/wiki/The_Canon_of_Medicine

Thesis I Definition and Scope of Medicine[edit]

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

 

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

 

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

 

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.”

 

Definition of body fluid[edit]

The Canon defines a humour as "that fluid, moist 'body' into which our aliment is transformed",[8]:77[12] and lists the four primary types of fluids as sanguineous, serous, bilious, and atrabilious. The secondary fluids are separated into "non-excrementitious" and "excrementitious".

THE FOUR HUMOURS DOMINATED MEDICINE FOR MOST OF HISTORY- IT IS BASED ON QUADRANT DICHOTOMIES

https://en.wikipedia.org/wiki/File:Humorism.svg

https://en.wikipedia.org/wiki/Humorism

Origins[edit]

The concept of four humors may have origins in Ancient Egyptian medicine[19] or Mesopotamia,[20] though it was not systemized until ancient Greek thinkers[21] around 400 BC directly linked it with the popular theory of the four elements: earth, fire, water and air (Empedocles).

 

Fåhræus (1921), a Swedish physician who devised the erythrocyte sedimentation rate, suggested that the four humours were based upon the observation of blood clotting in a transparent container. When blood is drawn in a glass container and left undisturbed for about an hour, four different layers can be seen. A dark clot forms at the bottom (the "black bile"). Above the clot is a layer of red blood cells (the "blood"). Above this is a whitish layer of white blood cells (the "phlegm"). The top layer is clear yellow serum (the "yellow bile").[22]

 

Islamic medicine[edit]

See also: Medicine in medieval Islam and Unani

Medieval medical tradition in the "Golden Age of Islam" adopted the theory of humorism from Greco-Roman medicine, notably via the Persian polymath Avicenna's The Canon of Medicine (1025). Avicenna summarized the four humors and temperaments as follows:[25]

 

Avicenna's four humors and temperaments

Evidence Hot Cold Moist Dry

Morbid states Inflammations become febrile Fevers related to serious humor, rheumatism Lassitude Loss of vigour

Functional power Deficient energy Deficient digestive power Difficult digestion

Subjective sensations Bitter taste, excessive thirst, burning at cardia Lack of desire for fluids Mucoid salivation, sleepiness Insomnia, wakefulness

Physical signs High pulse rate, lassitude Flaccid joints Diarrhea, swollen eyelids, rough skin, acquired habit rough skin, acquired habit

Foods and medicines Calefacients harmful, infrigidants[26] beneficial Infrigidants harmful, calefacients beneficial Moist articles harmful Dry regimen harmful, humectants beneficial

Relation to weather Worse in summer Worse in winter Bad in autumn

FOUR HUMOURS

https://en.wikipedia.org/wiki/File:Lavater1792.jpg

The four 'humours' or temperaments (Clockwise from top right; choleric; melancholic; sanguine; phlegmatic).

 

The comedy of humours is a genre of dramatic comedy that focuses on a character or range of characters, each of whom exhibits two or more overriding traits or 'humours' that dominates their personality, desires and conduct. This comic technique may be found in Aristophanes, but the English playwrights Ben Jonson and George Chapman popularized the genre in the closing years of the sixteenth century. In the later half of the seventeenth century, it was combined with the comedy of manners in Restoration comedy.

FOUR TEMPERAMENTS

https://simple.wikipedia.org/wiki/Four_temperaments

Four temperaments is a theory of psychology about personality. It suggests that four bodily fluids affect human personality traits and behaviour. The temperaments are sanguine, choleric, melancholy, and phlegmatic.

 

Contents [hide]

1 Humours

2 Personalities

2.1 Sanguine

2.2 Choleric

2.3 Melancholy

2.4 Phlegmatic

Humours[change | change source]

 

The four humours

Galen, a doctor from the Roman empire added characteristics to bodily fluids:

 

Mucus - Cold and damp

Black bile - Cold and dry

Yellow bile - Warm and Dry

Blood - Warm and damp

Galen thought that to cure illness you need to rebalance the fluids. If you, for example, have too much blood, you will need a remedy which is the opposite of warm and damp; something cold and dry.

 

Humour Season Element Organ Qualities Ancient name Modern MBTI Ancient characteristics

Blood spring air liver warm & moist sanguine artisan SP courageous, hopeful, amorous

Yellow bile summer fire spleen warm & dry choleric idealist NF easily angered, bad tempered

Black bile autumn earth gall bladder cold & dry melancholic guardian SJ despondent, sleepless, irritable

Phlegm winter water brain/lungs cold & moist phlegmatic rational NT calm, unemotional

CHLOROPHYL AND HEMOGLOBIN BOTH MERKABA STAR TETRAHEDRON- TETRA IS FOUR----
https://metatranspiration.com/…/peace-and-tetrahedron-the-…/
One of the things that has fascinated me over the years is that the fingerprint of the Creator is everywhere. Back in the early ‘90s when I was struggling with an overgrowth of systemic yeast, I tried blue-green algae. Algae is a superfood. Unless it is harvested from a clean source and processed properly, I do not recommend its use. One of the things that struck me at the time was that the nucleus of chlorophyll and the nucleus of hemoglobin are almost identical! The only difference is the center atom – in chlorophyll it is magnesium, in hemoglobin it is iron. But the most remarkable thing is that both are Star Tetrahedron. I call the Star Tetrahedron the fingerprint of God.

FOUR TYPES HAIR

https://en.wikipedia.org/wiki/Hair

Andre Walker system

This hair typing system is the most widely used system to classify hair. The system was created by the hairstylist of Oprah Winfrey, Andre Walker. According to this system there are four types of hair: straight, wavy, curly, kinky.

 

Type 1 is straight hair, which reflects the most sheen and also the most resilient hair of all of the hair types. It is hard to damage and immensely difficult to curl this hair texture. Because the sebum easily spreads from the scalp to the ends without curls or kinks to interrupt its path, it is the most oily hair texture of all.

Type 2 is wavy hair, whose texture and sheen ranges somewhere between straight and curly hair. Wavy hair is also more likely to become frizzy than straight hair. While type A waves can easily alternate between straight and curly styles, type B and C Wavy hair is resistant to styling.

Type 3 is curly hair known to have an S-shape. The curl pattern may resemble a lowercase "s", uppercase "S", or sometimes an uppercase "Z".[citation needed] This hair type is usually voluminous, "climate dependent (humidity = frizz), and damage prone." Lack of proper care causes less defined curls.

Type 4 is kinky hair, which features a tightly coiled curl pattern (or no discernible curl pattern at all) that is often fragile with a very high density. This type of hair shrinks when wet and because it has fewer cuticle layers than other hair types it is more susceptible to damage.

FOUR TYPES OF HAIR CONDITIONING

https://en.wikipedia.org/wiki/Greasy_hair

 

Greasy hair is a hair condition which is common in humans, one of four main four types of hair conditioning— normal, greasy, dry and greasy dry

16 SKIN PERSONALITIES- 16 SQUARES QMR

https://en.wikipedia.org/wiki/Baumann_Skin_Types

The Baumann Skin Types system is a skin-type classification system defining 16 skin personalities. This classification system was developed in 2004 by University of Miami dermatology professor Leslie Baumann, to subdivide research participants into specific phenotypes. She assigns binary values to four characteristics, so defining sixteen "skin personalities", or "skin types". These have been used in genetic research aimed at identifying the genes that contribute to skin characteristics such as dryness, oiliness, aging, pigmentation and sensitivity. The a survey-based typing system combines these individual skin attributes into 16 personalities that allow researchers to improve their ability to identify various skin phenotypes and use that knowledge for patient selection for clinical research trials and to recommend proper skincare ingredients and products. The classification system has been adopted by estheticians, dermatologists, consumers and retailers to match cosmeceutical ingredients and skin care products to specific skin types.[1] The type assigned is determined by a self-completed questionnaire, marketed as the "Baumann Skin Type Indicator" (BSTI).[2]

 

The typing system identifies four key skin attributes (dry/oily, sensitive/resistant, pigmented/non-pigmented and wrinkle-prone/tight), represented as D/O, S/R, P/N, and W/T. Combining these results in 16 possible types. For example, one type is ORPW (oily, resistant, pigmented, wrinkle-prone) while another is DSPT (dry, sensitive, pigmented, tight). More than just combinations of skin attributes, each type experiences different dermatologic problems, which indicate preventative measures and treatment options.[3]

 

There are 4 unique subtypes of sensitive skin, and they are all different, all sensitive subtypes have inflammation in common.

 

Acne subtype: Develops acne, whiteheads or blackheads

Rosacea subtype: Experiences recurring flushing, redness and a hot sensation

Stinging subtype: Develops stinging or burning of the skin

Allergic subtype: Develops redness, itching and flaking of the skin

MOST COME FROM FOUR FAMILIES- SAME THING IN THE STOMACH MOST BACTERIA FROM FOUR FAMILIES AND FOUR TYPES OF CELLS

https://en.wikipedia.org/wiki/Human_skin

The human skin is a rich environment for microbes.[5][6] Around 1000 species of bacteria from 19 bacterial phyla have been found. Most come from only four phyla: Actinobacteria (51.8%), Firmicutes (24.4%), Proteobacteria (16.5%), and Bacteroidetes (6.3%).

THE EPIDERMIS (SKIN) CONTAINS FOUR CELL TYPES

https://en.wikipedia.org/wiki/List_of_cutaneous_conditions

The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells.

FOUR TYPES OF CELLS IN THE EPIDERMIS (outer layer of skin)

https://en.wikipedia.org/wiki/Integumentary_system

This is the top layer of skin made up of epithelial cells. It does not contain blood vessels. Its main functions are protection, absorption of nutrients, and homeostasis. In structure, it consists of a keratinized stratified squamous epithelium comprising four types of cells: keratinocytes, melanocytes, Merkel cells, and Langerhans' cells.

TRANSCENDENT FOURTH DEGREE BURN

https://en.wikipedia.org/wiki/Burn

Burns that affect only the superficial skin layers are known as superficial or first-degree burns. They appear red without blisters and pain typically lasts around three days.[3][4] When the injury extends into some of the underlying skin layer, it is a partial-thickness or second-degree burn. Blisters are frequently present and they are often very painful. Healing can require up to eight weeks and scarring may occur. In a full-thickness or third-degree burn, the injury extends to all layers of the skin. Often there is no pain and the burn area is stiff. Healing typically does not occur on its own. A fourth-degree burn additionally involves injury to deeper tissues, such as muscle, tendons, or bone.[3] The burn is often black and frequently leads to loss of the burned part.[3][5]

 

Type[3] Layers involved Appearance Texture Sensation Healing Time Prognosis Example

Superficial (1st-degree) Epidermis[4] Red without blisters[3] Dry Painful[3] 5–10 days[3][16] Heals well;[3] Repeated sunburns increase the risk of skin cancer later in life[17] A sunburn is a typical first-degree burn.

Superficial partial thickness (2nd-degree) Extends into superficial (papillary) dermis[3] Redness with clear blister. Blanches with pressure.[3] Moist[3] Very painful[3] less than 2–3 weeks[3][11] Local infection/cellulitis but no scarring typically[11]

Second-degree burn of the thumb

 

Deep partial thickness (2nd-degree) Extends into deep (reticular) dermis[3] Yellow or white. Less blanching. May be blistering.[3] Fairly dry[11] Pressure and discomfort[11] 3–8 weeks[3] Scarring, contractures (may require excision and skin grafting)[11] Second-degree burn caused by contact with boiling water

Full thickness (3rd-degree) Extends through entire dermis[3] Stiff and white/brown[3] No blanching[11] Leathery[3] Painless[3] Prolonged (months) and incomplete[3] Scarring, contractures, amputation (early excision recommended)[11] Eight day old third-degree burn caused by motorcycle muffler.

4th-degree Extends through entire skin, and into underlying fat, muscle and bone[3] Black; charred with eschar Dry Painless Requires excision[3] Amputation, significant functional impairment, and, in some cases, death.[3]

FACE SKIN HAS UP TO 16 LAYERS- 16 SQUARES QMR

https://en.wikipedia.org/wiki/Lip

The skin of the lip, with three to five cellular layers, is very thin compared to typical face skin, which has up to 16 layers. With light skin color, the lip skin contains fewer melanocytes (cells which produce melanin pigment, which give skin its color). Because of this, the blood vessels appear through the skin of the lips, which leads to their notable red coloring. With darker skin color this effect is less prominent, as in this case the skin of the lips contains more melanin and thus is visually darker. The skin of the lip forms the border between the exterior skin of the face, and the interior mucous membrane of the inside of the mouth.

FOUR TYPES HIGHLIGHTS

https://en.wikipedia.org/wiki/Hair_highlighting

Hair highlighting/lowlighting is changing a person's hair color, using lightener or haircolor to color hair strands. There are four basic types of highlights: foil highlights, hair painting, frosting, and chunking. Highlights can be done in natural or unnatural colors. Color highlights come in four categories: temporary, semi-permanent, demi-permanent and permanent. Hair lightened with bleach or permanent color will be permanent until new growth begins to growth. Highlighted hair will make the hair appear fuller. Therefore, it is recommended on people with thin and fine hair. It also recommended for people with at least 50 % gray for easy blending and to diminish the line of demarcation once the new growth is showing.

https://en.wikipedia.org/wiki/Four_Eleven_Forty_Four

"Four Eleven Forty-Four", or "4-11-44" is a phrase that has been used repeatedly in popular music and as a reference to numbers allegedly chosen by poor African Americans for the purpose of gambling on lotteries.

FOUR UNIQUE HUES

https://en.wikipedia.org/wiki/Unique_hues

A concept of four unique hues of psychologist Charles Hubbard Judd (1917)

 

Unique hue is a term used in certain theories of color vision, which implies that human perception distinguishes between "unique" (psychologically primary) and composite (mixed) hues.[1] A unique hue is defined as a color which an observer perceives as a pure, without any admixture of the other colors.[2] There is a great deal of variability when defining unique hues experimentally.[3] Often the results show a great deal of interobserver and intraobserver variability leading to much debate on the number of unique hues.[4] Another source of variability is environmental factors in color naming. Despite the inconsistencies, often four color perceptions are associated as unique; “red”, “green”, “blue”, and “yellow”.

A concept of four unique hues of psychologist Charles Hubbard Judd (1917)

four species

https://en.wikipedia.org/wiki/Chestnut

Chestnuts belong to the family Fagaceae, which also includes oaks and beeches. The four main species are commonly known as European, Chinese, Japanese, and American chestnuts, some species called chinkapin or chinquapin:[4]

FOUR POOLS

https://en.wikipedia.org/wiki/Mana_Pools_National_Park

Mana means ‘four’ in Shona, in reference to the four large permanent pools formed by the meanderings of the middle Zambezi. These 2,500 square kilometres of river frontage, islands, sandbanks and pools, flanked by forests of mahogany, wild figs, ebonies and baobabs, is one of the least developed national parks in Southern Africa. It has the country’s biggest concentration of hippopotami and crocodiles and large dry season mammal populations of the zebra, elephant and Cape buffalo. The area is also home to other threatened species including the lion, cheetah, Cape wild dog, and near-threatened species including leopard and the brown hyena.

FOUR STAGE HOMOSEXUAL IDENTITY

https://en.wikipedia.org/wiki/Adolescence

In 1989, Troiden proposed a four-stage model for the development of homosexual sexual identity.[120] The first stage, known as sensitization, usually starts in childhood, and is marked by the child's becoming aware of same-sex attractions. The second stage, identity confusion, tends to occur a few years later. In this stage, the youth is overwhelmed by feelings of inner turmoil regarding their sexual orientation, and begins to engage sexual experiences with same-sex partners. In the third stage of identity assumption, which usually takes place a few years after the adolescent has left home, adolescents begin to come out to their family and close friends, and assumes a self-definition as gay, lesbian, or bisexual.[121] In the final stage, known as commitment, the young adult adopts their sexual identity as a lifestyle. Therefore, this model estimates that the process of coming out begins in childhood, and continues through the early to mid 20s. This model has been contested, and alternate ideas have been explored in recent years.

https://en.wikipedia.org/wiki/Sixteen_Military_Wives

"Sixteen Military Wives", sometimes referred to as "16 by 32", is a single released by The Decemberists from their third album, Picaresque.

FOUR GROUPS

https://en.wikipedia.org/wiki/Whippet

Eventually, the sport evolved and dogs were divided into four groups: those who hunted rabbits, which was not governed by rules; those who coursed hare, for which a set of rules was established; those trained to the rag; and those trained to chase a mechanical lure in a fashion similar to greyhound races.[9] Few of the Whippets of any of the four types were purebred, as maintaining a purebred bloodline was not considered as important as breeding dogs that could win races.[9] Many racing dogs were part terrier, part Greyhound, or part Lurcher.[9

https://en.wikipedia.org/wiki/Tapirus_merriami

During the Pleistocene era, four species of tapirs are known to have inhabited the North American continent. Along with T. merriami, Tapirus californicus also lived in California, Tapirus veroensis was found in Florida, Georgia, Kansas, Missouri and Tennessee, and Tapirus copei was found from Pennsylvania to Florida.[4]

 

First discovered and described in 1921 by American vertebrate paleontologist Childs Frick, T. merriami lived at the same time, and perhaps many of the same locations, as T. californicus,[5] but is believed to have preferred more inland habitats of southern California and Arizona. Like T. californicus and all living tapirs, it is believed to have been a relatively solitary species. Of the four known Pleistocene-era tapirs found on the North American continent, T. merriami was the largest.[4] T. merriami was a stout-bodied herbivore with short legs, a large, tapering head, and a short, muscular proboscis adept at stripping leaves from shrubs.[6]

THERE ARE FOUR LEVELS OF NUCLEIC ACID STRUCTURE- THE FOURTH IS TRANSCENDENT- ALSO IT DISCUSSES TETRALOOPS- TETRA IS FOUR

 

https://en.wikipedia.org/wiki/Nucleic_acid_structure

Nucleic acid structure refers to the structure of nucleic acids such as DNA and RNA. Chemically speaking, DNA and RNA are very similar. Nucleic acid structure is often divided into four different levels: primary, secondary, tertiary and quaternary.

 

The secondary structure of RNA consists of a single polynucleotide. Base pairing in RNA occurs when RNA folds between complementarity regions. Both single- and double-stranded regions are often found in RNA molecules. The antiparallel strands form a helical shape.[3] The four basic elements in the secondary structure of RNA are helices, loops, bulges, and junctions. Stem-loop or hairpin loop is the most common element of RNA secondary structure.[8] Stem-loop is formed when the RNA chains fold back on themselves to form a double helical tract called the stem, the unpaired nucleotides forms single stranded region called the loop.[9] Secondary structure of RNA can be predicted by experimental data on the secondary structure elements, helices, loops and bulges. Bulges and internal loops are formed by separation of the double helical tract on either one strand (bulge) or on both strands (internal loops) by unpaired nucleotides. A tetraloop is a four-base pairs hairpin RNA structure. There are three common families of tetraloop in ribosomal RNA: UNCG, GNRA, and CUUG (N is one of the four nucleotides and R is a purine).UNCG is the most stable tetraloop.[10] Pseudoknot is a RNA secondary structure first identified in turnip yellow mosaic virus.[11] Pseudoknots are formed when nucleotides from the hairpin loop pairs with a single stranded region outside of the hairpin to form a helical segment. H-type fold pseudoknots are best characterized. In H-type fold, nucleotides in the hairpin loop pairs with the bases outside the hairpin stem forming second stem and loop. This causes formation of pseudoknots with two stems and two loops.[12] Pseudoknots are functional elements in RNA structure having diverse function and found in most classes of RNA. DotKnot-PW method is used for comparative pseudoknots prediction. The main points in the DotKnot-PW method is scoring the similarities found in stems, secondary elements and H-type pseudoknots.[13]

FOUR STRAND QUADRANT SHAPE NUCLEIC ACID DESIGN

https://en.wikipedia.org/wiki/File:Неподвижная_структура_Холлидея_(англ.).svg

https://en.wikipedia.org/wiki/Nucleic_acid_structure

Nucleic acid design can be used to create nucleic acid complexes with complicated secondary structures such as this four-arm junction. These four strands associate into this structure because it maximizes the number of correct base pairs, with A's matched to T's and C's matched to G's. Image from Mao, 2004.[5]

FOUR TETRAMERS

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

Condon DE, Kennedy SD, Mort BC, Kierzek R, Yildirim I, Turner DH (June 2015). "Stacking in RNA: NMR of Four Tetramers Benchmark Molecular Dynamics". Journal of Chemical Theory and Computation. 11 (6): 2729–2742. doi:10.1021/ct501025q. PMC 4463549Freely accessible. PMID 26082675.

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QUADRUPLEXES IS TRANSCENDENT- IT IS THE HIGHEST IT GOES- QUAD IS FOUR

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

Quadruplexes[edit]

Besides double helices and the above-mentioned triplexes, RNA and DNA can both also form quadruple helices. There are diverse structures of RNA base quadruplexes. Four consecutive guanine residues can form a quadruplex in RNA by Hoogsteen hydrogen bonds to form a “Hoogsteen ring” (See Figure).[11] G-C and A-U pairs can also form base quadruplex with a combination of Watson-Crick pairing and noncanonical pairing in the minor groove.[14]

 

The core of malachite green aptamer is also a kind of base quadruplex with a different hydrogen bonding pattern (See Figure).[12] The quadruplex can repeat several times consecutively, producing an immensely stable structure.

 

The unique structure of quadruplex regions in RNA may serve different functions in a biological system. Two important functions are the binding potential with ligands or proteins, and its ability to stabilize the whole tertiary structure of DNA or RNA. The strong structure can inhibit or modulate transcription and replication, such as in the telomeres of chromosomes and the UTR of mRNA.[15] The base identity is important towards ligand binding. The G-quartet typically binds monovalent cations such as potassium, while other bases can bind numerous other ligands such as hypoxanthine in a U-U-C-U quadruplex.[14]

 

Along with these functions, the G-quadruplex in the mRNA around the ribosome binding regions could serve as a regulator of gene expression in bacteria.[16] There may be more interesting structures and functions yet to be discovered in vivo.

QUADRUPLEX HIGHEST LEVEL- FOURTH TRANSCENDENT

https://en.wikipedia.org/wiki/Hoogsteen_base_pair

Quadruplex structures[edit]

It also allows formation of secondary structures of single stranded DNA and RNA G-rich called G-quadruplexes (G4-DNA and G4-RNA) at least in vitro. It needs four triplets of G, separated by short spacers. This permits assembly of planar quartets which are composed of stacked associations of hoogsteen bonded guanine molecules.[5]

THE TETRALOOP

https://en.wikipedia.org/wiki/Stem-loop

The stability of the loop also influences the formation of the stem-loop structure. "Loops" that are less than three bases long are sterically impossible and do not form. Large loops with no secondary structure of their own (such as pseudoknot pairing) are also unstable. Optimal loop length tends to be about 4-8 bases long. One common loop with the sequence UNCG is known as the "tetraloop" and is particularly stable due to the base-stacking interactions of its component nucleotides.

TETRALOOP INTERACTION TETRA IS FOUR

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

Tetraloop-receptor interactions[edit]

 

Stick representation of a GAAA tetraloop - an example from the GNRA tetraloop family.[29]

Tetraloop-receptor interactions combine base-pairing and stacking interactions between the loop nucleotides of a tetraloop motif and a receptor motif located within an RNA duplex, creating a tertiary contact that stabilizes the global tertiary fold of an RNA molecule. Tetraloops are also possible structures in DNA duplexes.[30]

 

Stem-loops can vary greatly in size and sequence, but tetraloops of four nucleotides are very common and they usually belong to one of three categories, based on sequence.[31] These three families are the CUYG, UNCG and GNRA (see figure on the right) tetraloops.[32] In each of these tetraloop families, the second and third nucleotides form a turn in the RNA strand and a base-pair between the first and fourth nucleotides stabilizes the stemloop structure. It has been determined, in general, that the stability of the tetraloop depends on the composition of bases within the loop and on the composition of this "closing base pair".[33] The GNRA family of tetraloops is the most commonly observed within Tetraloop-receptor interactions.

 

 

GAAA Tetraloop and Receptor: Stick representation of tetraloop (yellow) and its receptor, showing both Watson-Crick and Hoogsteen base-pairing.[29]

“Tetraloop receptor motifs” are long-range tertiary interactions[34] consisting of hydrogen bonding between the bases in the tetraloop to stemloop sequences in distal sections of the secondary RNA structure.[35] In addition to hydrogen bonding, stacking interactions are an important component of these tertiary interactions. For example, in GNRA-tetraloop interactions, the second nucleotide of the tetraloop stacks directly on an A-platform motif (see above) within the receptor.[24] The sequence of the tetraloop and its receptor often covary so that the same type of tertiary contact can be made with different isoforms of the tetraloop and its cognate receptor.[36]

 

For example, the self-splicing group I intron relies on tetraloop receptor motifs for its structure and function.[24][35] Specifically, the three adenine residues of the canonical GAAA motif stack on top of the receptor helix and form multiple stabilizing hydrogen bonds with the receptor. The first adenine of the GAAA sequence forms a triple base-pair with the receptor AU bases. The second adenine is stabilized by hydrogen bonds with the same uridine, as well as via its 2'-OH with the receptor and via interactions with the guanine of the GAAA tetraloop. The third adenine forms a triple base pair.

TETRALOOP- TETRA IS THE HIGHEST TETRA IS FOUR

https://en.wikipedia.org/wiki/File:Tetraloop_Receptor_GAAA.png

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

GAAA Tetraloop and Receptor: Stick representation of tetraloop (yellow) and its receptor, showing both Watson-Crick and Hoogsteen base-pairing.[29]

TETRA IS FOUR

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

For instance, in the P4-P6 domain of the Tetrahymena thermophila group I intron, several ion-binding sites consist of tandem G-U wobble pairs and tandem G-A mismatches, in which divalent cations interact with the Hoogsteen edge of guanosine via O6 and N7.[48][49][50] Another ion-binding motif in the Tetrahymena group I intron is the A-A platform motif, in which consecutive adenosines in the same strand of RNA form a non-canonical pseudobase pair.[51] Unlike the tandem G-U motif, the A-A platform motif binds preferentially to monovalent cations. In many of these motifs, absence of the monovalent or divalent cations results in either greater flexibility or loss of tertiary structure.

TETRA IS FOUR

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

This unfortunate lack of scope would eventually be overcome largely because of two major advancements in nucleic acid research: the identification of ribozymes, and the ability to produce them via in vitro transcription. Subsequent to Tom Cech's publication implicating the Tetrahymena group I intron as an autocatalytic ribozyme,[58] and Sidney Altman's report of catalysis by ribonuclease P RNA,[59] several other catalytic RNAs were identified in the late 1980s,[60] including the hammerhead ribozyme. In 1994, McKay et al. published the structure of a 'hammerhead RNA-DNA ribozyme-inhibitor complex' at 2.6 Ångström resolution, in which the autocatalytic activity of the ribozyme was disrupted via binding to a DNA substrate.[61] In addition to the advances being made in global structure determination via crystallography, the early 1990s also saw the implementation of NMR as a powerful technique in RNA structural biology. Investigations such as this enabled a more precise characterization of the base pairing and base stacking interactions which stabilized the global folds of large RNA molecules.

A MINOR MOTIFS FOUR CLASSES

https://en.wikipedia.org/wiki/Nucleic_acid_tertiary_structure

A-minor motifs have been separated into four classes,[8] types 0 to III, based upon the position of the inserting base relative to the two 2’-OH’s of the Watson-Crick base pair. In type I and II A-minor motifs, N3 of adenine is inserted deeply within the minor groove of the duplex (see figure: A minor interactions - type II interaction), and there is good shape complementarity with the base pair. Unlike types 0 and III, type I and II interactions are specific for adenine due to hydrogen bonding interactions. In the type III interaction, both the O2' and N3 of the inserting base are associated less closely with the minor groove of the duplex. Type 0 and III motifs are weaker and non-specific because they are mediated by interactions with a single 2’-OH (see figure: A-minor Interactions - type 0 and type III interactions).

QUADRUPLEX FOUR IS THE HIGHEST- FOUR IS TRANSCENDENT- FIFTH IS QUESTIONABLE

https://en.wikipedia.org/wiki/G-quadruplex

In molecular biology, G-quadruplexes (also known as G4 DNA) are secondary structures[1] formed in nucleic acids by sequences that are rich in guanine. These structures are four stranded helical structures and occur naturally in nature. They are normally located near the ends of the chromosomes or the better known as the telomeric regions and in transcriptional regulatory regions of multiple oncogenes.[2] Four guanine bases can associate through Hoogsteen hydrogen bonding to form a square planar structure called a guanine tetrad, and two or more guanine tetrads can stack on top of each other to form a G-quadruplex. The placement and bonding to form G-quadruplexes are not random and serve very unusual functional purposes. The quadruplex structure is further stabilized by the presence of a cation, especially potassium, which sits in a central channel between each pair of tetrads.[3] They can be formed of DNA, RNA, LNA, and PNA, and may be intramolecular, bimolecular, or tetramolecular.[4] Depending on the direction of the strands or parts of a strand that form the tetrads, structures may be described as parallel or antiparallel. G-quadruplex structures can be computationally predicted from DNA or RNA sequence motifs, but their actual structures can be quite varied within and between the motifs, which can number over 100,000 per genome. Their activities in basic genetic processes are an active area of research in telomere, gene regulation, and functional genomics research (Rhodes et al., NAR 2015).[5]

 

 

 

(replacement figure 1)

Structure of a G-quadruplex. Left: a G-tetrad. Right: an intramolecular G-quadruplex

 

3D Structure of the intramolecular human telomeric G-quadruplex in potassium solution (PDB ID 2HY9). The backbone is represented by a tube. The center of this structure contains three layers of G-tetrads. The hydrogen bonds in these layers are represented by blue dashed lines.

Contents [hide]

1 Quadruplex topology

2 Telomeric quadruplexes

3 Non-telomeric quadruplexes

4 Quadruplex function

5 Ligands which bind quadruplexes

6 Quadruplex prediction techniques

7 Notes

8 References

9 External links

9.1 Quadruplex websites

9.2 Tools to predict G-quadruplex motifs

Quadruplex topology[edit]

The length of the nucleic acid sequences involved in tetrad formation determines how the quadruplex folds. Short sequences, consisting of only a single contiguous run of three or more guanine bases, require four individual strands to form a quadruplex. Such a quadruplex is described as tetramolecular, reflecting the requirement of four separate strands. Longer sequences, which contain two contiguous runs of three or more guanine bases, where the guanine regions are separated by one or more bases, only require two such sequences to provide enough guanine bases to form a quadruplex. These structures, formed from two separate G-rich strands, are termed bimolecular quadruplexes. Finally, sequences which contain four distinct runs of guanine bases can form stable quadruplex structures by themselves, and a quadruplex formed entirely from a single strand is called an intramolecular quadruplex.[6]

NEW GROUP III INTRON COMPOSED OF FOUR GROUPS- THE FOURTH IS THE HIGHEST

https://en.wikipedia.org/wiki/Twintron

Since the original discovery, there have been other reports of Group III twintrons and GroupII/III twintrons in Euglena gracilis chloroplast. In 1993 a new type of complex twintron composed of four individual group III introns has been characterized.[2] The external intron was interrupted by an internal intron containing two additional introns. In 1995 scientists discovered the first non-Euglena twintron in cryptomonad alga Pyrenomonas salina.[3] In 2004, several twintrons were discovered in Drosophila.[4]

QUADRANT BASED ON MATERIAL EATEN AND FEEDING STRATEGY - THE TWO DIMENSIONS MAKES FOUR QUADRANTS

 

Wayne Getz's consumer categories are based on material eaten (plant: green live, brown dead; animal: red live, purple dead; or particulate: grey) and feeding strategy (gatherer: lighter shades; miner: darker shades).[4]

 

 

https://en.wikipedia.org/wiki/File:ConsumerWikiPDiag.jpg

QUADRANT

CROSS SHAPED TREE

http://www.cbn.com/cbnnews/us/2009/June/Cross-Shaped-Tree-Impacts-Ind-Hospital/?Print=true

Cross-Shaped Tree Impacts Ind. Hospital

 

Some are calling it a natural occuring marvel of inspiration.

 

A tree in the shape of a cross outside of a hospital in Evansville, Ind. is having a big impact.

One employee at Deaconess Hospital recently discovered the cross while peering out a window.

She said seeing the tree cross changed her bad mood immediately.

Now the tree is getting a lot of attention from employees and patients.

The tree was not sculptured, but just grew that way naturally.

CRUCIFORM LIGAMENT KNEE

https://en.wikipedia.org/wiki/Anterior_cruciate_ligament

The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. They are also called cruciform ligaments as they are arranged in a crossed formation. In the quadruped stifle joint (analogous to the knee), based on its anatomical position, it is also referred to as the cranial cruciate ligament.[1] The anterior cruciate ligament is one of the four main ligaments of the knee, and the ACL provides 85% of the restraining force to anterior tibial displacement at 30 degrees and 90 degrees of knee flexion.[2]

THERE ARE FOUR LIGAMENTS IN THE KNEE AND THE C MEANS CRUCIATE WHICH MEANS CRUCIFORM THE CROSS

https://en.wikipedia.org/wiki/Anterior_cruciate_ligament

The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. They are also called cruciform ligaments as they are arranged in a crossed formation. In the quadruped stifle joint (analogous to the knee), based on its anatomical position, it is also referred to as the cranial cruciate ligament.[1] The anterior cruciate ligament is one of the four main ligaments of the knee, and the ACL provides 85% of the restraining force to anterior tibial displacement at 30 degrees and 90 degrees of knee flexion.[2]

CRUCIATE MEANS CRUCIFORM CROSS

https://en.wikipedia.org/wiki/Anterior_cruciate_ligament_injury

Anterior cruciate ligament injury occurs when the biomechanical limits of the ligament are exceeded (over-stretched). The anterior cruciate ligament (ACL) is an important internal stabilizer of the knee joint. The primary function of the ACL is to prevent hyperextension; its secondary function is to restrain tibial rotation and varus/valgus stress.[3]

IT IS CALLED CRUCIATE BECAUSE IT HAS FOUR COMPONENTS RESEMBLING A CROSS

https://en.wikipedia.org/wiki/Cruciate_anastomosis

The cruciate anastomosis is a circulatory anastomosis in the upper thigh of the inferior gluteal artery, the lateral and medial circumflex femoral arteries, and the first perforating artery of the profunda femoris artery. Also, the anastomotic branch of the posterior branch of the obturator artery.[1] The cruciate anastomosis is clinically relevant because if there is a blockage between the femoral artery and external iliac artery, blood can reach the popliteal artery by means of the anastomosis. The route of blood is through the internal iliac, to the inferior gluteal artery, to a perforating branch of the deep femoral artery, to the lateral circumflex femoral artery, then to its descending branch into the superior lateral genicular artery and thus into the popliteal artery.

 

Structure[edit]

The cruciate anastomosis is so-called because it resembles a cross. Its four components are:

 

inferior gluteal artery

lateral circumflex femoral artery (transverse branch of)

medial circumflex femoral artery (transverse branch of)

first perforating artery from profunda femoris (ascending branch of)

CRUCIATE MEANS CROSS

https://en.wikipedia.org/wiki/Stifle_joint

The joint is stabilized by paired collateral ligaments which act to prevent abduction/adduction at the joint, as well as paired cruciate ligaments. The cranial cruciate ligament and the caudal cruciate ligament restrict cranial and caudal translation (respectively) of the tibia on the femur. The cranial cruciate also resists over-extension and inward rotation, and is the most commonly damaged stifle ligament in dogs.

CRUCIFORM CARD
https://en.wikipedia.org/wiki/File:Cruciform_Triage_card.jpg
https://en.wikipedia.org/wiki/Triage_tag#Examples
The Cruciform triage card, used in the UK including the North Sea oil industry, by the Royal London Hospital during the 7 July 2005 London bombings and by medical and paramedical organisations worldwide. The International Cruciform has been produced for the Canada/North America (with appropriate terminology adjustments), and translated versions of the card are available for European and Asian markets. The Cruciform Evacuation System is a variation of the system applying Triage to mass planned and unplanned evacuation scenarios (e.g. hospital evacuations).
The Smart Tag from TSG Associates. Adopted by the State of New York in 2004, the British Military in 2002, used by London Ambulance Service in the 7 July 2005 London bombings and by the combined forces Afghanistan in 2006. The tag is also used in New York, Philadelphia, Boston and Nevada, and is mandated for use across the States of Connecticut and Massachusetts.

FOUR SETS OF INVERTED REPEATS

https://en.wikipedia.org/wiki/File:Pseudoknot-Inverted-Repeats.gif

https://en.wikipedia.org/wiki/Inverted_repeat

Inverted repeats are a key component of pseudoknots as can be seen in the illustration of a naturally occurring pseudoknot found in the human telomerase RNA component.[17] Four different sets of inverted repeats are involved in this structure. Sets 1 and 2 are the stem of stem-loop A and are part of the loop for stem-loop B. Similarly, sets 3 and 4 are the stem for stem-loop B and are part of the loop for stem-loop A.

 

Pseudoknot with four sets of inverted repeats. Inverted repeats 1 and 2 create the stem for stem-loop A and are part of the loop for stem-loop B. Similarly, inverted repeats 3 and 4 form the stem for stem-loop B and are part of the loop for stem-loop A.

CRUCIFORM STRUCTURE- TETRAPLEX- TETRAPLEX IS THE HIGHEST TETRA FOUR IS TRANSCENDENT
https://en.wikipedia.org/wiki/File:DNA_palindrome.svg
https://en.wikipedia.org/wiki/Inverted_repeat
The illustration shows an inverted repeat undergoing cruciform extrusion. DNA in the region of the inverted repeat unwinds and then recombines, forming a four-way junction with two stem-loop structures. The cruciform structure occurs because the inverted repeat sequences self-pair to each other on their own strand.[20]

The instability results from the tendency of inverted repeats to fold into hairpin- or cruciform-like DNA structures. These special structures can hinder or confuse DNA replication and other genomic activities.[6] Thus, inverted repeats lead to special configurations in both RNA and DNA that can ultimately cause mutations and disease.[8]

To a large extent, portions of nucleotide repeats are quite often observed as part of rare DNA combinations.[13] The three main repeats which are largely found in particular DNA constructs include the closely precise homopurine-homopyrimidine inverted repeats, which is otherwise referred to as H palindromes, a common occurrence in triple helical H conformations that may comprise either the TAT or CGC nucleotide triads. The others could be described as long inverted repeats having the tendency to produce hairpins and cruciform, and finally direct tandem repeats, which commonly exist in structures described as slipped-loop, cruciform and left-handed Z-DNA.[13]

Extruded cruciforms can lead to frameshift mutations when a DNA sequence has inverted repeats in the form of a palindrome combined with regions of direct repeats on either side. During transcription, slippage and partial dissociation of the polymerase from the template strand can lead to both deletion and insertion mutations.[8

non-B DB A Database for Integrated Annotations and Analysis of non-B DNA Forming Motifs.[21] This database is provided by The Advanced Biomedical Computing Center (ABCC) at then Frederick National Laboratory for Cancer Research (FNLCR). It covers the A-DNA and Z-DNA conformations otherwise known as "non-B DNAs" because they are not the more common B-DNA form of a right-handed Watson-Crick double-helix. These "non-B DNAs" include left-handed Z-DNA, cruciform, triplex, tetraplex and hairpin structures.[21] Searches can be performed on a variety of "repeat types" (including inverted repeats) and on several species.

Pearson, CE; Zorbas, H; Price, GB; Zannis-Hadjopoulos, M (October 1996). "Inverted repeats, stem-loops, and cruciforms: significance for initiation of DNA replication". Journal of cellular biochemistry. 63 (1): 1–22. doi:10.1002/(SICI)1097-4644(199610)63:1<1::AID-JCB1>3.0.CO;2-3. PMID 8891900.
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