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Leucism
Leucism () is a wide variety of conditions that result in the partial loss of pigmentation in an animal—causing white, pale, or patchy coloration of the skin, hair, feathers, scales, or cuticles, but not the eyes. It is occasionally spelled ''leukism''. Some genetic conditions that result in a "leucistic" appearance include piebaldism, Waardenburg syndrome, vitiligo, Chédiak–Higashi syndrome, flavism, isabellinism, xanthochromism, axanthism, amelanism, and Melanophilin mutations. Pale patches of skin, feathers, or fur (often referred to as "depigmentation") can also result from injury. Details ''Leucism'' is often used to describe the phenotype that results from defects in pigment cell differentiation and/or migration from the neural crest to skin, hair, or feathers during development. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells that can make pigment. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucistic Rock Pigeon
Leucism () is a wide variety of conditions that result in the partial loss of pigmentation in an animal—causing white, pale, or patchy coloration of the skin, hair, feathers, scales, or cuticles, but not the eyes. It is occasionally spelled ''leukism''. Some genetic conditions that result in a "leucistic" appearance include piebaldism, Waardenburg syndrome, vitiligo, Chédiak–Higashi syndrome, flavism, isabellinism, xanthochromism, axanthism, amelanism, and Melanophilin mutations. Pale patches of skin, feathers, or fur (often referred to as "depigmentation") can also result from injury. Details ''Leucism'' is often used to describe the phenotype that results from defects in pigment cell differentiation and/or migration from the neural crest to skin, hair, or feathers during development. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells that can make pigment. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Lion
The white lion is a rare color mutation of the lion, specifically the Southern African lion. White lions in the area of Timbavati are thought to have been indigenous to the Timbavati region of South Africa for centuries, although the earliest recorded sighting in this region was in 1938. White lions first became known to the English-speaking world in 1977 through the book ''The White Lions of Timbavati''. Description White lions are not albinos. Their white color is caused by a recessive trait, called leucism, derived from a less-severe mutation in the same gene that causes albinism, similar to the gene responsible for white tigers. They vary from blonde to near-white. This coloration does not appear to pose a disadvantage to their survival. White lions were considered to have been technically extinct in the wild between 1992 and 2004, when the Global White Lion Protection Trust achieved the first successful reintroduction of white lions to their natural habitat. These prides ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albinism
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 hours due to the lack of protection from UV radiation and their lack of camouflage to avoid predators. It is a common misconception that all albino animals have characteristic pink or red eyes (resulting from the lack of pigment in the iris allowing the blood vessels of the retina to be visible), however this is not the case for some forms of albinism. Familiar albino animals include in-bred strains of laboratory animals (rats, mice and rabbits), but populations of naturally occurring albino animals exist in the wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isabelline (colour)
Isabelline (; also known as isabella) is a pale grey-yellow, pale fawn, pale cream-brown or parchment colour. It is primarily found in animal coat colouring, particularly plumage colour in birds and, in Europe, in horses. It also has historically been applied to fashion. The first known record of the word was in 1600 as "isabella colour"; this use later became interchangeable in literature with "isabelline" after the latter was introduced into print in 1859. The origin of the word is unclear; the uncertainty prompted by this has generated several attempts to provide an etymology and led to one prominent legend. Usage and origins The first recorded use of ''isabella'' as the name of a colour in English was in the year 1600, to describe an item in Elizabeth I of England's wardrobe inventory: "one rounde gowne of Isabella-colour satten ... set with silver spangles". ''Isabelline'' as a derivative term was first used in the journal ''Ibis'' in 1859 by Henry Baker Tristram to describ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waardenburg Syndrome
Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or Heterochromia iridum, one blue eye and one brown eye), a white forelock or patches of light skin. These basic features constitute type 2 of the condition; in type 1, there is also a wider gap between the inner corners of the eyes called telecanthus, telecanthus, or dystopia canthorum. In type 3, which is rare, the arms and hands are also malformed, with Camptodactyly, permanent finger contractures or fused fingers, while in type 4, the person also has Hirschsprung's disease. There also exist at least two types (2E and PCWH) that can result in central nervous system (CNS) symptoms such as developmental delay and muscle tone abnormalities. The syndrome is caused by mutations in any of several genes that affect the Cell division, division and Cell migration, migration of neural crest cells d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piebald
A piebald or pied animal is one that has a pattern of unpigmented spots (white) on a pigmented background of hair, feathers or scales. Thus a piebald black and white dog is a black dog with white spots. The animal's skin under the white background is not pigmented. Location of the unpigmented spots is dependent on the migration of melanoblasts (primordial pigment cells) from the neural crest to paired bilateral locations in the skin of the early embryo. The resulting pattern appears symmetrical only if melanoblasts migrate to both locations of a pair and proliferate to the same degree in both locations. The appearance of symmetry can be obliterated if the proliferation of the melanocytes (pigment cells) within the developing spots is so great that the sizes of the spots increase to the point that some of the spots merge, leaving only small areas of the white background among the spots and at the tips of the extremities. Animals with this pattern may include birds, cats, cattl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypopigmentation
Hypopigmentation is characterized specifically as an area of skin becoming lighter than the baseline skin color, but not completely devoid of pigment. This is not to be confused with depigmentation, which is characterized as the absence of all pigment. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin. Some common genetic causes include mutations in the tyrosinase gene or OCA2 gene. As melanin pigments tend to be in the skin, eye, and hair, these are the commonly affected areas in those with hypopigmentation. Hypopigmentation is common and approximately one in twenty have at least one hypopigmented macule. Hypopigmentation can be upsetting to some, especially those with darker skin whose hypopigmentation marks are seen more visibly. Most causes of hypopigmentation are not serious and can be easily treated. Presentation Associated conditions It is seen in: * Albinism * Idiopathic guttate hypom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatophore
Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for animal coloration, coloration. Chromatophores are largely responsible for generating skin and eye color, eye colour in ectothermic animals and are generated in the neural crest during embryonic development. Mature chromatophores are grouped into subclasses based on their colour (more properly "hue") under white light: xanthophores (yellow), erythrophores (red), iridophores (reflective / iridescence, iridescent), leucophores (white), melanophores (black/brown), and cyanophores (blue). While most chromatophores contain pigments that absorb specific wavelengths of light, the color of leucophores and iridophores is produced by their respective scattering and optical interference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanocyte
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation. Melanocytes also have a role in the immune system. Function Through a process called melanogenesis, melanocytes produce melanin, which is a pigment found in the skin, eyes, hair, nasal cavity, and inner ear. This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from oxidation of already-existing melanin. There are both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book ''The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanin
Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against Ultraviolet, UV radiation. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, ''Eohippus'', into the large, single-toed animal of today. Humans began domesticating horses around 4000 BCE, and their domestication is believed to have been widespread by 3000 BCE. Horses in the subspecies ''caballus'' are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior. Horses are adapted to run, allowing them to quickly escape predators, and po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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