Animals Melanin

White or black animals can be explained by the concentration of melanin in the feathers or fur .<br /> The melanism is much rarer than the albinism in animals .<br /> <br /> <br /> The lack of melanin give a white or yellowish animal (presence of other pigments) red eyes ( albino ) as in the real white horse . On the contrary, excessive melanin concentration give an animal plumage or coat black ( melanistic ) as in the case of mutation nigripennis Blue Peafowl (Peacock nigripenne) or panther black.<br /> <br /> Non migration in feathers or hairs that give a white pigment in animal skin, eyes and legs normally colored as in the case of mutation alba of peacock blue (white peacock) and that of the gray horse . Non migration of melanocytes in the skin or apoptosis premature gives animals leucistic , all white, partially colored like the white tiger , or pie . Deficient tyrosinase, unable to operate at normal body temperature, gives the phenotype colourpoint .

White or black animals can be explained by the concentration of melanin in the feathers or fur . The melanism is much rarer than the albini...

Read More

Types of melanin

It has two main types of melanin each comprising two sub-groups, and a minor less known types:<br /> <br /> <br /> <ul> <li>the eumelanin pigment or dark, black or dark brown</li> <li>the pheomelanin pigment or light, tan, red or yellow</li> <li>the neuromelanin , present mainly in the substantia nigra (black substance) and the locus coeruleus (blue spot) of the brain</li> </ul>

It has two main types of melanin each comprising two sub-groups, and a minor less known types: the eumelanin pigment or dark, black or d...

Read More

Definition of Melanin

The melanins are major organic pigments responsible for the color of theintegument in the animal kingdom. In humans, the color of the skin , the hair andeyes are dependent primarily on its type and its concentration. Many animals also occur, including birds (coloring feathers ), many fungi, and some protozoans .<br /> <br /> <br /> Biological melanins are macromolecules produced mostly by the melanocytes , by addition or condensation of monomers formed from tyrosine ( eumelanin ) or tyrosine and cysteine ​​( pheomelanin ), with the help of the enzyme tyrosinase . A small proportion, as the neuromelanin of the substantia nigra of the human brain is not made ​​in melanocytes but is probably the metabolism of amine easy asdopamine .<br /> <br /> <br /> There are also artificial melanins: polyacetylenes , polyanilines , and polypyrroleblack or brown, and their copolymers , and they have an industrial or biotechnological application.<br /> <br /> <br /> The main role of melanin is the pigment protection against radiation UV . In some animals, the melanophores, chromatophores holders melanin contribute to camouflage or report their transformations emotion, stress or a change in the environment (temperature, etc..). Some invertebrates, pathogens are encapsulated in melanin, which thus help home defense against infections. It also appears that its carboxylate groups and phenol hydroxyl medium can isolate some harmful components when in excess, such as heavy metals

The melanins are major organic pigments responsible for the color of theintegument in the animal kingdom. In humans, the color of the skin ,...

Read More

Melanin in humans

Melanins ( Greek μέλας (MELAS) "black") are reddish, brown or black pigments formed by the enzymatic oxidation of tyrosine arise (enzymatic browning) and the coloring of the skin , hair , feathers and eyes cause, except for albinism . They come in vertebrates and insects, as a colorant in the ink of cuttlefish before and also in microorganisms and plants. Made in vertebrates is melanin in the melanocytes of the skin and in the retina and iris of the eye.<br /> <br /> <br /> Melanin occurs in humans, especially in two versions: a brown-blackish ( eumelanin ), which differ from the amino acids tyrosine and L-dopa derived and a lighter yellowish-red ( pheomelanin ) variant, which contains sulfur. There are also different color variants, so-called allomelanins from hydroxybenzenes arise. These are mainly found in plants, fungi and bacteria. Almost always contact the melanins as mixed types and are also linked to lipids or proteins.<br /> <br /> <br /> The melanin in human skin and the hair are mixed forms of eumelanins and the sulfur-containing phaeomelanins. The mixing ratio of these two types of melanin is co-determines the skin type of a person. The content of pheomelanin is particularly high in deep red hair and takes about brown and black hair from back. The melanin is stimulated by UVB radiation and it probably serves as a light protection from the harmful effects of UV radiation of the sun. One of the main arguments for the UV protection is the observation that heavily pigmented populations to a lesser extent to sonneninduziertem skin cancer (" melanoma ") cancer than less pigmented populations. Meanwhile, the photochemical processes which make melanin at an excellent UV filter, has been studied. It has been shown that melanin converts more than 99.9% of the radiation energy into harmless heat. This is done by the ultrafast internal conversion (s: internal conversion) from the electronically excited state to vibrational states of the molecule. With this ultra-fast conversion, the lifetime of the excited state shortened. This prevents the formation of free radicals. The excited state of the melanin is very short-lived, and therefore it offers an excellent photoprotection .<br /> <br /> <br /> Red-haired people have a higher probability of developing melanoma. Therefore, it is assumed that this type of melanin protects the skin less efficient.<br /> <br /> <br /> Due to genetic predisposition or by acquired over time damage to the genetic material may be disturbed, the synthesis of melanin. A reduced formation leads to hypopigmentation . If production is blocked, so missing the color in skin, hair and eyes, resulting in a very bright white skin, an unusually bright hair color and blue, blue-gray or green eyes found that depending on the angle of light red may appear. One speaks of albinism and referred the affected organisms as albinos. In case of overproduction ( hyperpigmentation ) occur more dark spots in the skin ( liver spots , freckles ), the malignant ( melanoma may be). The melanin production can by the drug Rucinol be specifically interrupted.<br /> <br />

Melanins ( Greek μέλας (MELAS) "black") are reddish, brown or black pigments formed by the enzymatic oxidation of tyrosine arise (...

Read More