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Equine Vision
The equine eye is one of the largest of any land mammal. Its visual abilities are directly related to the animal's behavior; for example, it is active during both day and night, and it is a prey animal. Both the strengths and weaknesses of the horse's visual abilities should be taken into consideration when training the animal, as an understanding of the horse's eye can help to discover why the animal behaves the way it does in various situations. The anatomy of the equine eye The equine eye includes the eyeball and the surrounding muscles and structures, termed the adnexa. The eyeball The eyeball of the horse is not perfectly spherical, but rather is flattened anterior to posterior. However, research has found the horse does not have a ramped retina, as was once thought. The wall of the eye is made up of three layers: the internal or nervous tunic, the vascular tunic, and the fibrous tunic. * The nervous tunic (or retina) is made up of cells which are extensions of the brain, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elastin
Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of vertebrates and used in places where mechanical energy is required to be stored. Function The ''ELN'' gene encodes a protein that is one of the two components of elastic fibers. The encoded protein is rich in hydrophobic amino acids such as glycine and proline, which form mobile hydrophobic regions bounded by crosslinks between lysine residues. Multiple transcript variants encoding different isoforms have been found for this gene. Elastin's soluble precursor is tropoelastin. The characterization of disorder is consistent with an ent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palomino
Palomino is a genetic color in horses, consisting of a gold coat and white mane and tail; the degree of whiteness can vary from bright white to yellow. Genetically, the palomino color is created by a single allele of a dilution gene called the cream gene working on a "red" (chestnut) base coat. Palomino is created by a genetic mechanism of incomplete dominance, hence it is not considered true-breeding. However, most color breed registries that record palomino horses were founded before equine coat color genetics were understood as well as they are today, therefore the standard definition of a palomino is based on the visible coat color, not heritability nor the underlying presence of the dilution gene. Due to their distinct color, palominos stand out in a show ring, and are much sought after as parade horses. They were particularly popular in movies and television during the 1940s and 1950s. One of the most famous palomino horses was Trigger, known as "the smartest horse i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dilution Gene
A dilution gene is any one of a number of genes that act to create a lighter coat color in living creatures. There are many examples of such genes: General Diluted coat colors have melanocytes, but vary from darker colors due to the concentration or type of these pigment-producing cells, not their absence. Pigment dilution, sometimes referred to as hypomelanism, has been called leucism, albinism (perfect, impartial, or dilute), ghosting, paling, and isabellinism. *Albinism describes a condition where pigment cells synthesize little or no pigment *Leucism describes a condition that creates loss of pigment cells Cats *Cat coat genetics discusses many dilution genes in cats Dogs In dogs, a mutation of the MLPH locus known as the dilute gene causes eumelanin to lighten while pheomelanin remains almost unchanged. Dogs of some breeds with the dilute gene often suffer from Colour dilution alopecia (CDA). Appearance Of the colour shades found in the coat of dogs, the light brown cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cream Gene
The cream gene is responsible for a number of horse coat colors. Horses that have the cream gene in addition to a base coat color that is chestnut will become palomino if they are heterozygous, having one copy of the cream gene, or cremello, if they are homozygous. Similarly, horses with a bay base coat and the cream gene will be buckskin or perlino. A black base coat with the cream gene becomes the not-always-recognized smoky black or a smoky cream. Cream horses, even those with blue eyes, are not white horses. Dilution coloring is also not related to any of the white spotting patterns. The cream gene (''CCr'') is an incomplete dominant allele with a distinct dosage effect. The DNA sequence responsible for the cream colors is the cream allele, which is at a specific locus on the solute carrier family 45 member 2 (''SLC45A2'') gene (previously known as ''MATP'' and ''OCA4'', among others). Its general effect is to lighten the coat, skin and eye colors. When one copy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterochromia
Heterochromia is a variation in coloration. The term is most often used to describe color differences of the iris, but can also be applied to color variation of hair or skin. Heterochromia is determined by the production, delivery, and concentration of melanin (a pigment). It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury. It occurs in humans and certain breeds of domesticated animals. Heterochromia of the eye is called heterochromia iridum or heterochromia iridis. It can be complete or sectoral. In complete heterochromia, one iris is a different color from the other. In sectoral heterochromia, part of one iris is a different color from its remainder. In central heterochromia, there is a ring around the pupil or possibly spikes of different colors radiating from the pupil. Though multiple causes have been posited, the scientific consensus is that a lack of genetic diversity is the primary reason behind heterochromia, at least in domestic anima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sabino Horse
A sabino horse with extensive roaning Sabino describes a distinct pattern of white spotting in horses. In general, Sabino patterning is visually recognized by roaning or irregular edges of white markings, belly spots, white extending past the eyes or onto the chin, white above the knees or hocks, and "splash" or "lacy" marks anywhere on the body. Some sabinos have patches of roan patterning on part of the body, especially the barrel and flanks. Some sabinos may have a dark leg or two, but many have four white legs. Sabino patterns may range from slightly bold face or leg white markings—as little as white on the chin or lower lip—to horses that are fully white. The known causes of the sabino patterns are the SB-1 allele and several other dominant white (W) alleles on the ''KIT'' gene. The genetics behind some types of sabino, such as that found in Clydesdales, have not yet been identified. Some genes, such as Sabino-1, are incomplete dominants, producing irregular spo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overo
Overo refers to several genetically unrelated pinto coloration patterns of white-over-dark body markings in horses, and is a term used by the American Paint Horse Association to classify a set of pinto patterns that are not tobiano. ''Overo'' is a Spanish word, originally meaning "like an egg".''American Paint Horse Association's Guide to Coat Color Genetics'' American Paint Horse Association, 2007. Accessed August 19, 2008 The most common usage refers to frame overo, but and [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Splashed White
Splashed white or splash is a horse coat color pattern in the "overo" group of spotting patterns that produces pink-skinned, white markings. Many splashed whites have very modest markings, while others have the distinctive "dipped in white paint" pattern. Blue eyes are a hallmark of the pattern, and splash may account for otherwise "solid" blue-eyed horses. Splashed white occurs in a variety of geographically divergent breeds, from Morgans in North America to Kathiawari horses in India. The splashed white pattern is also associated with congenital deafness, though most splashed whites have normal hearing. Splashed white can be caused by multiple variants across two different genes, for which genetic testing is available. Characteristics The splashed white pattern is characterized by the appearance of having been dipped, feet-first, into white paint. Blue eyes are common, but not universal. The margins of the white markings are crisp, smooth, blocky, and well-defined.Brooks, S. ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinto Horse
A pinto horse has a coat color that consists of large patches of white and any other color. The distinction between "pinto" and "solid" can be tenuous, as so-called "solid" horses frequently have areas of white hair. Various cultures throughout history appear to have selectively bred for pinto patterns. Many breeds of horses carry pinto patterns. Pinto coloring, known simply as "coloured" in nations using British English, is the most popular in the United States. While pinto-colored horses are not considered as a "breed", several competing color breed registries have formed to encourage the breeding of pinto-colored horses. The word "paint" was sometimes used to describe pinto horses. In current usage, "paint" is specifically used for the American Paint Horse (APHA), which is a pinto-colored horse with identifiable American Quarter Horse or Thoroughbred bloodlines. Pinto patterns are visually and genetically distinct from the leopard complex spotting patterns characteri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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