. The biology of marine animals. Marine animals; Physiology, Comparative. PIGMENTS AND COLOURS OH O —C2H5 481 —OH. CHOH—CH3 -OH OH O ECHINOCHROME A OH O SPINOCHROME A Indoles. These include indigoid pigments and melanins, basically sub- stances containing a phenopyrrol nucleus. Indigoid pigments are produced by certain gastropods, and include indigo and the purple dye dibromindigo, secreted by Murex, Mitra and Nucella. This substance is the dyestuff Tyrian purple which was used so extensively by the ancients. It is produced by a special hypobranchial gland, and stored as the colourless leuco c
. The biology of marine animals. Marine animals; Physiology, Comparative. PIGMENTS AND COLOURS OH O —C2H5 481 —OH. CHOH—CH3 -OH OH O ECHINOCHROME A OH O SPINOCHROME A Indoles. These include indigoid pigments and melanins, basically sub- stances containing a phenopyrrol nucleus. Indigoid pigments are produced by certain gastropods, and include indigo and the purple dye dibromindigo, secreted by Murex, Mitra and Nucella. This substance is the dyestuff Tyrian purple which was used so extensively by the ancients. It is produced by a special hypobranchial gland, and stored as the colourless leuco com- pound. When secreted and exposed to sunlight, it becomes transformed into the purple pigment dibromindigo (purpurin). No physiological role has been established for indigoid pigments in animals, and they may well be excretory products (6, 58, 80). In general the dark or black pigments of animals belong to the group of melanins, which have a colour range from yellow to jet black. They tend to be resistant substances, insoluble in water and the usual solvents, but dissolved by strong alkalis. Chemically they are indole derivatives of relatively high molecular weight, originating usually from tyrosine through the agency of tyrosinase. The melanins which occur in different animals in reality comprise a group of diverse substances, differing in degree of oxidation and complexity. The reactions may be summarized— Tyrosinase Tyrosinase Tyrosine ^DOPA —— ->Hallachrome - +o Intermediates +o + 0 Melanins +o The intermediate compound DOPA. is 3,4-dihydroxyphenylalanine which has been found in certain animals. Hallachrome, a red intermediate stage in the oxidation of tyrosine, occurs naturally in the polychaete Halla parthenopeia, where it may be involved in cellular respiration. Brown and black melanin pigments are found in sponges (Chondrosid), coelenter- ates (dark varieties of Metridium senile, coloured areas of the jellyfish Pelagia noctiluca), annelids (photorecept
Size: 1986px × 1258px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectmarineanimals, booksubjectphysiology
