engleski

Pigment Regression and Albinism in Astyanax Cavefish

The reduction of pigmentation is a hallmark of cave-adapted animals. Cavefish depigmentation involves i) a decrease in the number of melanophores, which is controlled by many different genes ; ii) a change in the coloration of melanophores from black to brown due to mutations in the mc1r gene ; and iii) in some populations, the complete shutdown of melanin synthesis (albinism), caused by a block in the first step of the pathway mediated by the oca2 gene. The likely evolutionary force responsible for the decrease in melanophore number is neutral mutation and genetic drift, whereas direct or indirect natural selection may be responsible for albinism. A potential benefit of albinism could be a shift of excess L- tyrosine substrate from the melanin synthesis pathway to enhance the catecholamine synthesis pathway. Further progress in understanding cavefish depigmentation should be helped by the identification of additional genes controlling this process.

pigment, Astyanax

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