Color vision of the coelacanth (Latimeria chalumnae) and adaptive evolution of rhodopsin (RH1) and rhodopsin-like (RH2) pigments.
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 (lambda max) at 478 nm and 485 nm, respectively. These blue-shifted lambda max 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 lambda max values of visual pigments more than 5 nm. Among these, D83N, E1220, M207L, and A292S are associated strongly with the adaptive blue shifts in the lambda max values of RH1 and RH2 pigments in vertebrates.
Yokoyama
S
S
Department of Biology, Syracuse University, NY 13244-1220, USA. syokoyam@mailbox.syr.edu
D000222:Adaptation, Physiological; D019943:Amino Acid Substitution; D000818:Animals; D003118:Color Perception / Q000235:genetics*; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics*; D006801:Humans; D008958:Models, Molecular; D010802:Phylogeny; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry / Q000235:genetics*
D012243:Rhodopsin