title: Conserved repertoire of orthologous vomeronasal type 1 receptor genes in ruminant species.
abstract: BACKGROUND
  In mammals, pheromones play an important role in social and innate reproductive behavior within species. In rodents, vomeronasal receptor type 1 (V1R), which is specifically expressed in the vomeronasal organ, is thought to detect pheromones. The V1R gene repertoire differs dramatically between mammalian species, and the presence of species-specific V1R subfamilies in mouse and rat suggests that V1R plays a profound role in species-specific recognition of pheromones. In ruminants, however, the molecular mechanism(s) for pheromone perception is not well understood. Interestingly, goat male pheromone, which can induce out-of-season ovulation in anestrous females, causes the same pheromone response in sheep, and vice versa, suggesting that there may be mechanisms for detecting "inter-species" pheromones among ruminant species.
  
  
  RESULTS
  We isolated 23 goat and 21 sheep intact V1R genes based on sequence similarity with 32 cow V1R genes in the cow genome database. We found that all of the goat and sheep V1R genes have orthologs in their cross-species counterparts among these three ruminant species and that the sequence identity of V1R orthologous pairs among these ruminants is much higher than that of mouse-rat V1R orthologous pairs. Furthermore, all goat V1Rs examined thus far are expressed not only in the vomeronasal organ but also in the main olfactory epithelium.
  
  
  CONCLUSIONS
  Our results suggest that, compared with rodents, the repertoire of orthologous V1R genes is remarkably conserved among the ruminants cow, sheep and goat. We predict that these orthologous V1Rs can detect the same or closely related chemical compound(s) within each orthologous set/pair. Furthermore, all identified goat V1Rs are expressed in the vomeronasal organ and the main olfactory epithelium, suggesting that V1R-mediated ligand information can be detected and processed by both the main and accessory olfactory systems. The fact that ruminant and rodent V1Rs have distinct features suggests that ruminant and rodent V1Rs have evolved distinct functions.
authors.affiliation: Laboratory of Frontier Science, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan. aa077135@mail.ecc.u-tokyo.ac.jp
authors.forename: Hiromi
authors.initials: H
authors.lastname: Ohara
authors.forename: Masato
authors.initials: M
authors.lastname: Nikaido
authors.forename: Atsuko
authors.initials: A
authors.lastname: Date-Ito
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Mogi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Okamura
authors.forename: Norihiro
authors.initials: N
authors.lastname: Okada
authors.forename: Yukari
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mori
authors.forename: Kimiko
authors.initials: K
authors.lastname: Hagino-Yamagishi
mesh_terms: D000818:Animals; D002417:Cattle / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics; D006041:Goats / Q000235:genetics*; D051379:Mice; D009831:Olfactory Mucosa / Q000378:metabolism; D010802:Phylogeny; D051381:Rats; D018035:Receptors, Odorant / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012756:Sheep / Q000235:genetics*; D013045:Species Specificity; D019147:Vomeronasal Organ / Q000378:metabolism
chemical_list: D018035:Receptors, Odorant