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The genetic mechanism behind human skin color is mainly regulated by the enzyme tyrosinase, which creates the color of the skin, eyes, and hair shades. [14] [15] Differences in skin color are also attributed to differences in size and distribution of melanosomes in the skin. [9] Melanocytes produce two types of melanin.
Albinism is a congenital condition characterized in humans by the partial or complete absence of pigment in the skin, hair and eyes. Albinism is associated with a number of vision defects, such as photophobia, nystagmus, and amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers.
Alpine salamanders produce a toxin from their skin, and both fully melanistic, black salamanders and spotted individuals produce the compound. [ 32 ] Studies done that traced DNA histories have suggested that the original alpine salamander phenotype was black with some yellow spots, meaning that the fully black color evolved over time and was ...
The first modern humans had darker skin as the indigenous people of Africa today. Following migration and settlement in Asia and Europe, the selective pressure dark UV-radiation protecting skin decreased where radiation from the sun was less intense. This resulted in the current range of human skin color.
Vitiligo is a skin disease where people lack melanin in certain areas in the skin. People with oculocutaneous albinism typically have a very low level of melanin production. Albinism is often but not always related to the TYR gene coding the tyrosinase enzyme. Tyrosinase is required for melanocytes to produce melanin from the amino acid ...
In birds, albinism has been defined as "a total lack of both melanins in feathers, eyes and skin as a result of an inherited absence of tyrosinase", [18] however, this ignores the effects of other pigments and structural colours. Albino Rock dove. An albino bird has a white beak, white plumage, non-coloured skin, white talons and pink or red ...
For years, a man from Bangladesh lived with "tree man" syndrome.. Abul Bajandar's hands and feet grew foot-long "roots" that left him unable to feed himself, move around, work or wear normal clothing.
Leucism (/ ˈ l uː s ɪ z əm,-k ɪ z-/) [2] [3] [4] is a wide variety of conditions that result in 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. [4] It is occasionally spelled leukism.