On the origin of the olfactory receptor family: receptor genes of the jawless fish (Lampetra fluviatilis)

Characterization of novel GPCR gene coding locus in amphioxus genome: Gene structure, expression, and phylogenetic analysis with implications for its involvement in chemoreception

“…4), namely, the lamprey OR family may be a paraphyletic group. Nevertheless, all the ORs of lamprey show spatially restricted expression patterns within the nasal epithelium similar to gnathostome ORs (Berghard and Dryer, 1998;Freitag et al, 1999), whereas Amphi-GPCR1 is ubiquitously expressed in the rostral epithelium. Until now, the genomic organization of the lamprey ORs has been completely unknown, and I could not obtain any evidence that shows the existence of other GPCR genes located in close register with the Amphi-GPCR1 locus.…”

“…4). The vertebrate ORs have subdivided structurally and functionally into three major groups: the class I receptors for the detection of water-soluble substances in an aquatic environment, class II receptors for volatile substances in a terrestrial environment (Freitag et al, 1998), and recently identified novel ORs from lamprey (Berghard and Dryer, 1998;Freitag et al, 1999). The present phylogenetic analysis corroborates the class I [Zebrafish OR2.5 ϩ Zebrafish OR 13.2 ϩ Xenopus class I OR] and class II [mouse OR 245 ϩ chick OR6 ϩ chick OR7 ϩ Xenopus class II OR ϩ mouse B2 OR ϩ dog CfOlf 14 ϩ CfOlf 3] assignments, whereas the lamprey clade is not supported.…”

“…The present phylogenetic analysis corroborates the class I [Zebrafish OR2.5 ϩ Zebrafish OR 13.2 ϩ Xenopus class I OR] and class II [mouse OR 245 ϩ chick OR6 ϩ chick OR7 ϩ Xenopus class II OR ϩ mouse B2 OR ϩ dog CfOlf 14 ϩ CfOlf 3] assignments, whereas the lamprey clade is not supported. As seen in Table 1, lamprey ORs can be further subdivided into two groups; one group (LOR1 and LOR2) possesses all of the conserved motifs diagnostic for the ORs of gnathostomes, whereas the other group (LOR3, LOR4, and LOR14) lacks several motifs in the C-terminal half region whose amino acid sequences are similar to the vertebrate amine receptors instead of ORs (Berghard and Dryer, 1998;Freitag et al, 1999).…”

“…In the first class, all motifs characteristic of higher vertebrate OR family members are conserved. The other class does not possess all of these motifs; instead, the deduced amino acid sequence downstream of IC II shows similarity to amine receptors (Berghard and Dryer, 1998;Freitag et al, 1999). It has been suggested that the latter class of the lamprey ORs is Table 1 Sequence Identity Matrix an evolutionarily novel group that might have been adapted for the detection of lamprey-specific odorants like bile acids released by ammocoete larvae.…”

Immunolocalization of G‐Protein Alpha Subunits in the Olfactory System of the Cartilaginous Fish Scyliorhinus Canicula

“…Studies about the organization of the olfactory system and the modality of signal transduction have been carried out in different species of bony fishes and also in jawless fishes (Freitag et al, 1999;Speca et al, 1999;Belanger et al, 2003;Hansen et al, 2003Hansen et al, , 2004Korsching, 2009), but these topics have yet to be explored in Chondrichthyes. The olfactory system of Chondrichthyes has been studied mainly from a morphological point of view (Ebbesson and Heimer, 1970;Theisen et al, 1986;Franceschini and Ciani, 1993;Takami et al, 1994;Ferrando et al, 2006aFerrando et al, ,b, 2007a; its development has been only partially described (Fishelson and Baranes, 1997;Ferrando et al, 2007b;Ferrando, 2008).…”