Аннотация:The coelacanth, a 'living fossil', lives at a depth of about 200 m near the coast of the Comoros archipelago in the Indian Ocean and receives only a narrow range of light at about 480 nm. To see the entire range of 'color' the Comoran coelacanth appears to use only rod-specific RH1 and cone-specific RH2 visual pigments, with the optimum light sensitivities (λmax) at 478 nm and 485 nm, respectively. These blue-shifted λmax values of RH1 and RH2 pigments are fully explained by independent double amino acid replacements E122Q/A292S and E122Q/M207L, respectively. More generally, currently available mutagenesis experiments identify only 10 amino acid changes that shift the λmax values of visual pigments more than nm. Among these, D83N, E122Q, M207L, and A292S are associated strongly with the adaptive blue shifts in the λmax values of RH1 and RH2 pigments in vertebrates.
