Abstract
BackgroundMammalian olfactory receptors (ORs) are encoded by the largest mammalian multigene family. Understanding the OR gene repertoire in the cattle genome could lead to link the effects of genetic differences in these genes to variations in olfaction in cattle.ResultsWe report here a whole genome analysis of the olfactory receptor genes of Bos taurus using conserved OR gene-specific motifs and known OR protein sequences from diverse species. Our analysis, using the current cattle genome assembly UMD 3.1 covering 99.9% of the cattle genome, shows that the cattle genome contains 1,071 OR-related sequences including 881 functional, 190 pseudo, and 352 partial OR sequences. The OR genes are located in 49 clusters on 26 cattle chromosomes. We classified them into 18 families consisting of 4 Class I and 14 Class II families and these were further grouped into 272 subfamilies. Comparative analyses of the OR genes of cattle, pigs, humans, mice, and dogs showed that 6.0% (n = 53) of functional OR cattle genes were species-specific. We also showed that significant copy number variations are present in the OR repertoire of the cattle from the analysis of 10 selected OR genes.ConclusionOur analysis revealed the almost complete OR gene repertoire from an individual cattle genome. Though the number of OR genes were lower than in pigs, the analysis of the genetic system of cattle ORs showed close similarities to that of the pig.
Highlights
Mammalian olfactory receptors (ORs) are encoded by the largest mammalian multigene family
We identified 1,423 OR generelated sequences with lengths of 900–1,000 base pairs
The locations of the OR genes were analyzed as per their relative positions in the cattle genome by grouping them into gene clusters according to their positional proximity
Summary
Mammalian olfactory receptors (ORs) are encoded by the largest mammalian multigene family. Understanding the OR gene repertoire in the cattle genome could lead to link the effects of genetic differences in these genes to variations in olfaction in cattle. Odorant molecules are detected by olfactory receptors (ORs), which belong to the G-protein-coupled receptor superfamily and contain 7 transmembrane domains [1]. The genes encoding OR proteins comprise the largest superfamily in the mammalian genome. Understanding OR repertoires and individual variations among the same species may be important for determining the potential of individual animals associated with economic traits in livestock animals such studies have not been reported. Characterization and classification of the bovine OR gene repertoire with high accuracy could help to better understand the relationship between animal behavior and olfaction in domestic animals and the characteristics of OR systems in artiodactyl mammals. We analyzed the cattle genome assembly UMD 3.1, identified the nearly complete olfactory subgenome of cattle, and compared it with other species
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