Divergent evolution among teleost V1r receptor genes.
The survival of vertebrate species is dependent on the ability of individuals to adequately interact with each other, a function often mediated by the olfactory system. Diverse olfactory receptor repertoires are used by this system to recognize chemicals. Among these receptors, the V1rs, encoded by a very large gene family in most mammals, are able to detect pheromones. Teleosts, which also express V1r receptors, possess a very limited V1r repertoire. Here, taking advantage of the possibility to unequivocally identify V1r orthologs in teleosts, we analyzed the olfactory expression and evolutionary constraints of a pair of clustered fish V1r receptor genes, V1r1 and V1r2. Orthologs of the two genes were found in zebrafish, medaka, and threespine stickleback, but a single representative was observed in tetraodontidae species. Analysis of V1r1 and V1r2 sequences from 12 different euteleost species indicate different evolutionary rates between the two paralogous genes, leading to a highly conserved V1r2 gene and a V1r1 gene under more relaxed selective constraint. Moreover, positively-selected sites were detected in specific branches of the V1r1 clade. Our results suggest a conserved agonist specificity of the V1R2 receptor between euteleost species, its loss in the tetraodontidae lineage, and the acquisition of different chemosensory characteristics for the V1R1 receptor.
Pfister
Patrick
P
Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland.
Randall
Jerome
J
Montoya-Burgos
Juan I
JI
Rodriguez
Ivan
I
D020121:5' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D005399:Fishes; D008969:Molecular Sequence Data; D018035:Receptors, Odorant / Q000737:chemistry / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D019147:Vomeronasal Organ / Q000378:metabolism*
D020121:5' Untranslated Regions; D018035:Receptors, Odorant