gene cream is responsible for a number of horsehair colors. Horses that have cream genes in addition to the base color of the chestnut mantle will become palomino if they are heterozygous, have one copy of the cream gene, or cremello, if they are homozygous. Similarly, a horse with a base coat of the bay and cream genes will be the skin of a deer or perlino. The black base layer with cream gene becomes the one that is not always recognized black smoky or smoky cream. The cream horse, even with blue eyes, is not a white horse. The dye dilution is also not associated with any of the white patches.
Cream gene ( C Cr ) is an incomplete dominant allele with different dosing effects. The sequence of DNA responsible for the cream color is the cream allele, located at the specific locus of the MATP gene. The effect is generally to brighten the color of fur, skin and eyes. When one copy of the allele is present, it dilutes the "red" pigment to yellow or gold, with a stronger effect on the mane and tail, but does not thin black to a significant degree. When two copies of the allele are present, both the red and black pigments are affected; red hair is still a cream, and black hair becomes reddish. One copy of the allele has minimal impact on eye color, but when two copies are present, the horse will be blue-eyed in addition to light coat color.
The cream gene is one of several hypomelanism genes or dilutions identified on the horse. Therefore, it is not always possible to say with color only whether the C Cr allele is present without DNA testing. Other possible dilution genes may mimic some of the effects of cream genes in either single or multiple copies including pearl genes, dapple silver genes, and champagne genes. Horses with genes can also mimic a copy of the cream genes. To complicate matters further, it is possible for a horse to carry more than one type of dilution gene, sometimes giving rise to the staining that researchers refer to as pseudo double encute.
The discovery of the cream gene has a significant effect on the reproduction, allowing homozygous blue-eyed creams to be recognized by many descendant registers who have previously registered palominos but forbid cremellos, under false assumptions that homozygous creams are the form of Albinism.
Video Cream gene
The resulting color
The color of the cream feather is explained by their relationship with the three "basic" coat colors: brown, bay, and black. All horses get two copies of the MATP gene; one from the Sire, and one from the dam. A horse may have a cream allele or a non-cream allele on each gene. Those who have two non-cream alleles will not show the true nature of the cream. Horses with one cream allele and one non-cream allele, popularly called "single dilution," show special features: all the red pigments in the mantle are gold, while the black pigment is unaffected or only subtly affected. These horses are usually palomino, deer skin, or smoky black. These horses often have light brown eyes. The horse with 2 copies of the cream allele also shows special features: a cream-colored coat, pale blue eyes, and reddish skin. These horses are usually called cremello, perlino, or smoky cream.
Heterozygous creams ("single dilute")
The horses that are heterozygous creams, that is, have only one copy of the cream genes, have a lighter hair coat. The exact color of the creamy cream feather produced depends on the base color of the underlying base. Unless also influenced by other unrelated genes, they nourish the dark skin and brown eyes, although some dilute heterozygous can be born with pink skin that darkens with age. Some have slightly lighter and yellow eyes. However, dilute heterozygous (CR) cream should not be confused with horses carrying champagne fluids. Champagne (CH) champagne is born with pink pumpkin skin and blue eyes, which are dark within days to yellow, green or light brown, and their skin gets darker dark skin around the eyes, snout, and genitals when the animal is ripe. It is also possible for heterozygous horse creams to carry more than one other dilution allele. ( see "Mimic cream," below ) In such cases, they may show some characteristics that are more typical of dilute homozygotes.
Palomino is the best known cream-based fur color, and is produced by the action of one cream allele on a chestnut mantle. It is characterized by cream or white mane and tail and yellow or gold coat. The classic gold color similar to newly minted gold coins is common, but there are other variations: the darkest shades called sooty palomino, unusual but most commonly seen in Morgans, can include mane and tail with dark hair and heavy dappling inside the mantle. The most pale varieties can be almost white, maintaining darker skin and eyes, sometimes mistaken with kremello, and are called isabellas in some places.
Buckskin is also a well-known color, produced by the action of one cream gene in the mantle bay. All red hair in the base coat is diluted to gold. Black areas, such as manes, tails and feet, are generally unaffected. Cream gene working on the "blood bay" coat, the most red color, pale gold with black dots. They are sometimes called buttermilk buckskins . The cream gene that acts in the darkest bay, (sometimes mistaken for brown seal) can melt into a dirty deer skin. Really brown deer skin can be very difficult to identify because almost all of its black coat. Only red marks around the eyes, snout, elbow and groin, turned into gold, which can give it.
Smoky black , a horse with a black base coat and one copy of a cream allele, less well known than two golden colors. Because one copy of the cream gene primarily affects the red pigment, with only a subtle effect on black, smoky black can be very difficult to identify. Smoky blacks may have reddish-haired hairs in their ears, and experienced horse people can detect something "off" about the smoky black layer, although the slightly glossy look is often associated with sun bleaching, which can also be seen in real blacks.. The most pale can be misinterpreted for bay or chestnut heart, especially if exposed to the elements. The smoky black coat tends to react strongly to the sun and sweat, and a lot of smoky black turns brown with a very reddish mane and tail. Bleaching because of the elements means that the foot retains its color better, and can take on the look of having dark spots like a bay horse. Smokeless blacks, however, will lack the rich red tones in the mantle, instead of supporting the brown and orange tones. Because smoky blacks are often not recognized as such, breeders sometimes think that cream genes are "passed" for generations.
Although there are "color breed" registries for palomino and buckskin horses, who generally record horses based on real phenotypes and do not require DNA color tests, it is unlikely that these colors will breed "true" because of the action of one copy of the cream allele. Crossing two contaminated heterozygotes will statistically produce 25% base color, 25% dilute homozygous, and 50% dilute heterozygotes.
Homozygous Cream ("double dilute")
When the horse is homozygous, which means it has two copies of the cream allele, the strongest color dilution occurs.
- Cremellos is homozygous chestnut cream, and has a creamy body â € <â €
- Perlinos is a homozygous cream place, which also has a cream-colored body but a slightly rosy mane and tail rather than a cremello.
- Smoky Creams is a creamy black skin â € <â €
These three colors are difficult to distinguish from each other, and are often only clearly identified after DNA testing. While the red and black pigments turn into creams, the black pigment retains a bit of color and tends to have a reddish or rusty color. Thus all the red coats turned ivory, the all-black coat turned into a rusty cream, and the mantle of the bay had an ivory body with slightly darker dots.
Horses with two copies of the cream allele can be collectively called double-dilute, homozygous cream, or blue eye cream, and they share a number of characteristics. Pale blue eyes, paler than unmigrated blue eyes associated with white or white, and reddish skin. Really pigmented pink skin, which is associated with white markings, is evident in reddish reddish skin, especially when their coats are moistened. The pale shades of the double-seer coat are not white, while the darkest ones are clearly rusty. Their coats can be described as almost white or ivory in addition to creams.
White coats, pale blue eyes, and bright pink skin distinguish a double-sealed mantle from a true white horse. True white horses have unpigmented skin and hair due to the incomplete migration of melanocytes from neural crystals during development.
There is no health damage associated with the cream genes. This also applies to normal variations of skin, hair and eye tones that are encoded in the human MATP gene. True white hair coloring can be produced by at least half a dozen known genes, and some are associated with health defects. Some genes that encode white or almost white when heterozygous, popularly called "dominant white", may be lethal to the homozygous embryo. Other specific mutations in type B endothelin genes (EDNRB) are associated with frame overo patterns resulting in Lethal white syndrome if homozygous, but carriers may be identified by DNA testing.
Maps Cream gene
Prevalence
Cream gene is found in many breeds. It is common in American descent including American Quarter Horse, Morgan, American Saddlebred, Tennessee Walking Horse, and Missouri Fox Trotter. It is also seen on Miniature horses, Akhal-Teke, Icelandic horses, Connemara horses, and Welsh ponies. It is even found in certain pathways of Thoroughbreds, Warmbloods, and Lusitano. The Andalusian horses have conflicting standards, with the cream genes recognized by some registries, but not explicitly mentioned by others. The cream genes are completely absent from the Arab horse genepool, and are also not found in strict color requirements, such as Friesian horses.
Cream imitates
Other feather colors can mimic the appearance of cream color. The presence or absence of cream genes can always be verified using DNA testing. Also, as described in "Mixed dilute," below, horses can simultaneously carry more than one dilution gene. The dilution genes which, by themselves, may be confused with the dilution of the cream including the following:
- Bay dun vs. Buckskin : the action of genes in the bay produces a coat like pig skin. Additional confusion occurs because in some countries, it is still common to refer to buckskins as "dun", especially on British pony breeds. Bay duns tend to have a coat color that is flatter, more brown or peanut butter compared to bronze, and also shows primitive signs.
- Amber champagne vs. Buckskin : the action of the Champagne gene in the bay can also produce a coat like pig skin. Champagne can be identified with freckled skin spots, brown eyes, and brown (not black).
- Flaxen chestnut vs. Palomino : Horses that have light chestnut coats with ramie mane and tail, as found in Haflinger breeds, can be likened to palominos. However, unlike chestnuts, palomino is inherently a heterozygous condition and thus can not breed properly. In addition, even the mildest chestnut will retain a "red" character in hair, rather than gold.
- Gold champagne vs. Palomino : the action of the Champagne genes on chestnut for years is called palombino squash that is skinned . However, hazeled and younger hazel skin and eyes identify golden champagne, which can otherwise look like a palomino.
- Pearls vs. Palomino : the action of pearl genes occurs only in the red coat when the pearl allele is homozygous. In such cases, red hair is lightened into apricot color.
- Pseudo double-dilute vs. Cremello : A horse that has one cream allele and one pearl allele can resemble a homozygous cream, including pink skin and blue eyes. The combination of one cream and one Champagne allele can also produce the same phenotype, although it can be distinguished by brighter yellow or blue eyes and pale skin, with few spots.
- White vs. Dilute Dark : White horses with blue or dark eyes and pink skin are born white and remain so for life. Kremello and isabelline-bearing horses can approach a nearly white color, but have a skin pigment, indicated by a little peach skin color and a blue eye cream having a less distinct blue color when compared to the unpigmented blue-eye color.
- Gray vs. Lightweight : The gray horse is born with a normal color and grows lighter in its mantle, while the double-glazed cream does not. The grays that are not affected by the dilution genes do not have blue eyes or pink skin except those due to white markings. However, there are records of palominos, buckskins, smoky blacks, and double-dilute creams that also carry the gray genes.
The attenuated mix
If a horse carries more than one type of dilution gene, additional mimic creams and other unique colors may occur. The combined effects of champagne and single cream gene can be difficult to distinguish from double-dilute creams. Spotted skin and greenish eyes, or genealogical knowledge can produce clues, although the mystery can also be solved by DNA testing.
Pearl gene or "barbink factor" is a recessive gene that only affects the red pigment. When one copy of each pearl and cream is present, the effect is very similar to cremello. Dissolve the pearl gene combining with one copy of the cream gene known as the "watery pseudo-double" and produces a dilute phenotype of cream that includes pale skin and blue/green eyes. DNA testing and patience are effective in determining the case.
Some of the terms used to describe this combination include:
- Dunalino, yellow dun or palomino dun : chestnut-based coat with one cream allele and at least one allele. The dots are reddish, but the layers are pale, the gold color is flatter and the primitive signs are visible.
- Dunskin, buckskin dun , or buttermilk dun : a bay-based mantle with one cream allele and at least one allele. It's quite difficult to distinguish it from a regular place. They are a slightly more pale color, and retain their dark dots and primitive marks.
- Cream dun, Cremello dun or linebacked cremello : blue-eyed cream horse that also carries the genes. Primitive signs associated with the color dun are usually quite visible, especially on horses with a base layer of the bay or black.
- Smoky grulla, silver grulla or black dun smoky : a black coat with one cream allele and at least one allele. The effect is extra-pale grulla.
- Double cream champagne : any blue eyed cream that also carries the champagne genes. The nature of the champagne, in some known individual, is not visible. Her skin is quite pink.
- Amber Cream or Buckskin champagne : a bay-based mantle with one cream allele and at least one champagne allele. The skin and eyes have the characteristics of champagne like skin spots, while the coat is a pale color. The point is a soft grayish pale brown.
- Classic cream or Smoky black champagne : a black coat with one cream allele and at least one champagne allele. is also an acceptable term. Like the amber cream, they retain the champagne features in the skin and eyes, and range from pale buffs to pale grayish browns. Although the coat is black, the mane and tail tend to be darker.
- Gold cream : a chestnut-based coat with one cream allele and at least one champagne allele. Previously referred to as "ivory champagne." The nature of champagne remains in the skin and eyes, and the coat is a thorough ivory color.
- Sable cream or Brown buckskin champagne : a chocolate-based mantle with one cream allele and at least one champagne allele. The color of the coat falls between the yellow cream and the classic.
- Silver deer's skin : a bay-based mantle with one cream allele and at least one dapple silver allele. The effect varies, because the silver dapple does not act on the red coat, but the deer skin gold tone is somewhat lost.
- Silver smoky black : a black coat with one cream allele and at least one silver allele. The effect varies from chestnut-like silver-like black. Lighter eyes can help identify.
Inheritance and expression
The cream spot is located in the exon 2 MATP genes; Single nucleotide polymorphisms produce aspartic acid-to-asparagine substitution (N153D). DNA tests offered by various laboratories detect these mutations. The MATP gene encodes an illustrated protein having a role in melanogenesis in humans, rats, and medaka. Mice are affected by homologous conditions to exhibit irregularly shaped melanosomes creams, which are organelles in melanocytes that directly produce pigment.
Genes in horses such as Frame and Sabino1 produce white patches by disturbing or limiting the migration of melanocytes from neural crystals, while the cream mutations affect the pigment properties generated by melanocytes. Therefore, the skin, eyes, and hair of the horse with the mutation of the cream are not short of melanocytes, melanosomes, or melanin, but rather show hypomelanism.
Before mapping the cream genes, the locus is titled C for "color". There are two alleles in the series: alleles, recessive wildtype C and incomplete dominant C Cr . The C Cr allele represents the MATP N153D mutation.
- C/C homozygous recessive is not affected by the cream and does not have the correct cream properties.
- C/C Cr heterozygot has one cream allele, and one non-cream wildtype allele. Only red pigments in diluted hair, as seen on the skin and palominos.
- C Cr /C Cr homozigot (homozygous cream) does not have a wildtype non-cream allele. The red and black pigments in the hair are diluted to cream, the eyes are light blue and the skin is reddish pink.
Cream was first formally studied by Adalsteinsson in 1974, which reported that the inheritance of palomino and deer skin color in Icelandic horses follow a dominant "semi-dominant" or incomplete model. Adalsteinsson also notes that on heterozygotes, only red pigments (pheomelanin) are diluted.
The discovery that the color of the palomino feather is closely related to the color of the cream feather is very significant. At one time, double dilution, especially cremellos, was barred from registration by many breed organizations. Cremello is considered by some to be a deadly white or albino dye and the potential for genetic damage. There are also known health implications of albinism in humans, and cultural prejudices; while heroic figures like Roy Rogers drove a golden palomino, "Albino" in Mary O'Hara Thunderhead depicts a horse with a strange defect. These feather colors bring very different cultural differences. Because the experience of palomino and horsehair breeders shows that the breeds of blue-eye cream from these animals are not genetically defective, some research that occurred almost thirty years after the Adalsteinsson study that identifies the nature of cream dilution is directly supported by the recorder breeds that historically prohibit blue-eyed cream.
Cryptic cream
The special effects of cream cream on the red pigment have not been explained. Champagne dilution affects both black and red pigments alike, silver dapple genes affect only the black pigment, and pearls show recessive recessive mode and only affect the red pigment. Unlike cream genes, pearls do not seem to affect the mane and tail to a greater extent than the body mantle, the most obvious cream feature illustrated in the colors of the palomino coat. The character of this cream gene is also unexplained. The differences in effects on red and black pigments are easy to identify in deer skin, with their black dots, but also seen in C Cr /C Cr homozygous: perlinos (homozygous cream on layer of bay) often retain darker dots of cream.
This unusual feature allows so-called cryptic creams . Certain percentages of dark bays, brown seals, and dark horses show subtle dilutions such as their coats for incorrectly registered. In a study mapping the cream genes, three horses were listed as brown seals, dark coves or completely black smoky bays and deer skins. This is one of the ways in which the cream genes are transmitted through generations without being identified. Horses born palomino, deer skin, and smoky black, but also carry the gray genes, have a hair coat that turns white as they age and are usually listed as "gray" rather than as the color of their birth. This is particularly a common occurrence in Connemara breeds. Horses that are sold after turning completely into gray can surprise the breeder by producing a golden offspring or cream.
This effect - a strong expression on the red pigment - is also seen in the mantle pattern gene on the horse. In general, white markers are more pervasive in chestnut than in non-chestnut, to the extent that homozygous non-chestnut (carrying the "Extension" (E) gene and possibly also carrying Agouti genes) is simpler than non-chestnutgous. chestnut heterozygotes for the E genes. This effect has also been identified and studied in complex patterns of Leopard.
Similar conditions in other animals
The MATP genes are highly sustainable, especially among mammals. It can also occur in the zebra but can only occur in captivity. The 82% human MATP gene is identical to the mouse MATP gene, 79% identical to the rat MATP gene, 35% in the zebrafish version, and 30% identical to the fruit MATP gene. This gene is best known in humans as the location of mutations that produce human IV-type oculocutaneous albinism (OCA4). Type IV oculocutaneous albinism, like other types of human albinism, results in hypopigmentation of the skin and eyes, with increased rates of skin cancer and reduced visual acuity. None of these effects are linked to the horse cream genes. Other human MATP polymorphisms produce normal pigment variations, particularly bright skin, light eyes, and mild hair in Caucasian populations.
A polymorphism in the mouse MATP gene is known to be the cause of the underwhite color mantle phenotype . The phenotype was first identified in the 1960s, and has since been mapped successfully. Affected individuals experience decreased eye and feather pigmentation, and irregularly shaped melanosomes.
See also
References
Source of the article : Wikipedia
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