THE ROD AND GREEN CONE OPSINS OF 2 AVIAN SPECIES, THE BUDGERIGAR, MELOPSITTACUS-UNDULATUS, AND THE MALLARD DUCK, ANAS-PLATYRHYNCHUS

The genes for the rod and rod-like green cone opsins in two avian spec ies, the budgerigar, Melopsittacus undulatus, and the mallard duck, An as platyrhynchus, are identified on the basis of amino acid identity w ith the equivalent chicken sequences and their placement into a single phylogenetic clade with the rod and rod-like green cone opsin genes f rom other vertebrate species. Since the two bird species studied are t axonomically quite distinct, this would indicate that this rod-like gr een cone opsin gene, although absent in mammals, is common in the Aves . The two avian pigments differ consistently at site 122, consistent w ith the reported role of this site in determining the rate of metarhod opsin II formation and decay in rod and cone pigments. Candidate sites are identified to compensate for the known spectral effects of substi tution at this site. (C) 1997 Elsevier Science B.V.