Cloning and characterization of an odorant receptor in five Pacific salmon

Abstract

The olfactory system of fish is extremely important as it is able to recognize and distinguish a vast of odorous molecules that are involved in wide ranges of behaviors including reproduction, homing, kin recognition, feeding and predator avoidance; all of which are paramount for their survival. We cloned and characterized one type olfactory receptors (ORs) from five salmonids:keta), masu salmon (O. masou) and rainbow trout (O. mykiss). Lacustrine sockeye salmon olfactory receptor 1 (LSSOR1) showed high sequence homology to the OR subfamily, and was expressed only in the olfactory epithelium (as indicated by PCR amplified genomic DNA and cDNA). OR genes from the five salmonids examined all showed strong homology (96-99%) to each other. Hypervariable regions, believed to be ligand-binding pockets, showed homologous completely matched amino acid sequences except for one amino acid in pink salmon olfactory receptor 1 (PSOR1), revealing that these ORs may be well conserved among salmon species.These results suggest that the isolated 5 salmonid ORs might play an important role in salmon life cycles.

Sequence conservation among orthologous vomeronasal type 1 receptor-like (ora) genes does not support the differential tuning hypothesis in Salmonidae

“…We found that high levels of sequence conservation among salmOR300-1 orthologs, as previously described by Morinishi et al (2007), are not unique to this salmonid OR gene. Instead sequences for other genes from this mOR subfamily are conserved at similar or even higher levels among salmonid species (Table 2).…”

“…For example, the first mOR that we isolated from the O. kisutch genome is nearly identical to a gene described from five other Pacific salmon by Morinishi et al (2007), with high synteny in 5′ and 3′ flanking sequences. We found this gene also to be present in S. salar, O. clarkii and O. tschawycha.…”

“…Percent amino acid sequence identities greater than 60% and 40% were used to verify subfamily and family gene clades, respectively (sensuAlioto and Ngai, 2005). This objective nomenclature system facilitated organization and analyses of our data, which included distinctly novel gene sequences, as well as sequences similar or identical to salmonid OR genes previously described with various nomenclatures (Dukes et al, 2006;Morinishi et al, 2007;Wickens et al, 2001).…”

“…We found this gene also to be present in S. salar, O. clarkii and O. tschawycha. We included the sequences of Morinishi et al (2007) AB232550, AB255033-AB255036) and treated these genes as orthologs of salmOR300-1. In addition to salmOR300-1, we identified three novel genes from this mOR subfamily: salmOR300-2, salmOR300-3 and salmOR300-4 ( Table 2).…”

Molecular characterization and histochemical demonstration of salmon olfactory marker protein in the olfactory epithelium of lacustrine sockeye salmon (Oncorhynchus nerka)

“…Several ORN-related proteins except for OMP and GST have been identified and applied as molecular markers to study olfactory function, including olfactory receptors (ORs: Morinishi et al, 2007), and calretinin (calcium-binding protein: Castro et al, 2008) in the olfactory system of several other salmonid fish. However, a single ORN expresses only one allele of a given OR gene (Chess et al, 1994) although the regulation of OR gene expression is unclear in the salmon ORN at present.…”