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BioEssays 7/2012
Publication year - 2012
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.201290029
Subject(s) - postsynaptic potential , postsynaptic density , substructure , blueprint , excitatory postsynaptic potential , citation , computer science , process (computing) , neuroscience , cognitive science , biology , psychology , world wide web , engineering , genetics , programming language , mechanical engineering , structural engineering , receptor , inhibitory postsynaptic potential
Pheomelanin ‐ a pigment that may have evolved as an excretory mechanism . Higher vertebrates synthesize two forms of melanin: eumelanin and pheomelanin. While eumelanin has well known adaptive benefits, the mechanisms by which pheomelanin has evolved remain a mystery because of several physiological costs and no clear benefits. In this issue (pages 565–568 ), Galván et al. suggest that pheomelanin has evolved because the incorporation of thiol groups to the structure of this pigment helps to remove cysteine, which can be toxic if in excess. Pheomelanogenesis may thus be favored when environmental conditions promote excess cysteine. This may explain why humans with a pheomelanic phenotype are more common at high latitudes, and raises the question whether these humans may have a greater ability to avoid diseases associated with excess cysteine. The photo shows a common kingfisher Alcedo atthis exhibiting orange belly by the presence of pheomelanin in feathers (Toral et al. 2008, Comp Biochem Physiol B).