Materia melanica: further dark thoughts.
The view is advanced that melanogenesis arose evolutionarily as a detoxification pathway for intrinsically-generated orthoquinones. The primary impetus for the production of orthoquinones may have been their general antibiotic properties and the utility of these chemical species in forming covalent cross-links between proteins, as illustrated by cuticular sclerotization in insects. It is argued that polymerization to give rise to visible pigments may have originated as a pathway for the inactivation of orthoquinones. The possible evolutionary advantages accruing from the generation of melanin are discussed with special reference to acuity of photoreceptors and the physico-chemical properties of melanin, as well as the contribution of melanin to protective colouration or display.
Riley
P A
PA
Division of Molecular Pathology, University College London, England.
D000900:Anti-Bacterial Agents; D005075:Biological Evolution; D006197:Hair / Q000502:physiology; D008543:Melanins / Q000096:biosynthesis / Q000378:metabolism*; D008670:Metals / Q000633:toxicity; D008958:Models, Molecular; D011809:Quinones / Q000737:chemistry / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D008543:Melanins; D008670:Metals; D011809:Quinones