Evolution and expression patterns of olfactory receptors β subtype in Megalobrama amblycephala
To explore the potential role of olfactory receptors β subtype(OR-β)in the evolution of feeding adaptation in fish,we analyzed the OR-β genes from 12 fish species with different feeding habits in-cluding Megalobrama amblycephala,Ctenopharyngodon idellus,Cynoglossus semilaevis,Gadus morhua,Gasterosteus aculeatus,Larimichthys crocea,Paralichthys olivaceus,Danio rerio,Oreochromis niloticus,Oryzias latipes,Sinocyclocheilus graham and Xiphophorus maculatus.We also detected the expression pat-terns of the OR-β in the muscle,olfactory epithelium,olfactory bulb and brain of M.amblycephala.The results of evolutionary analysis showed that the number of OR-β varied greatly among fish species with dif-ferent feeding habits.Herbivorous M.amblycephala and C.idellus had 20 copies and 14 copies,respective-ly,while carnivorous and omnivorous fish had an average of 1 and 4 copies,respectively.The results of se-lection pressure analysis showed that a total of 19 branches undergo positive selection,including 9 OR-β genes and 10 branch sites.Among them,the OR-β-4 and OR-β-14 gene of M.amblycephala(P<0.01)experienced strong positive selection.In addition,the OR-β of several Cyprinidae species,such as M.am-blycephala,C.idellus,D.rerio and S.grahami,were clustered into one brand,which was positively se-lected and included 9 OR-β genes of M.amblycephala.The results of qPCR showed that 10 OR-β genes were highly expressed in the olfactory epithelium of M.amblycephala at 12-months of age and 24-months of age.OR-β-9 and OR-β-10 were also expressed in the olfactory bulb and brain tissue,while other OR-β genes were not expressed.Taken together,these results showed that the OR-β genes of the two herbivo-rous fish were specifically expanded and highly expressed in the olfactory epithelium,suggesting that OR-β might play potential crucial role in adapting the diets of herbivores.
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万方数据
维普
