Abstract
BackgroundInsects and animals can recognize surrounding environments by detecting thousands of chemical odorants. Olfaction is a complicated process that begins in the olfactory epithelium with the specific binding of volatile odorant molecules to dedicated olfactory receptors (ORs). OR proteins are encoded by the largest gene superfamily in the mammalian genome.ResultsWe report here the whole genome analysis of the olfactory receptor genes of S. scrofa using conserved OR gene specific motifs and known OR protein sequences from diverse species. We identified 1,301 OR related sequences from the S. scrofa genome assembly, Sscrofa10.2, including 1,113 functional OR genes and 188 pseudogenes. OR genes were located in 46 different regions on 16 pig chromosomes. We classified the ORs into 17 families, three Class I and 14 Class II families, and further grouped them into 349 subfamilies. We also identified inter- and intra-chromosomal duplications of OR genes residing on 11 chromosomes. A significant number of pig OR genes (n = 212) showed less than 60% amino acid sequence similarity to known OR genes of other species.ConclusionAs the genome assembly Sscrofa10.2 covers 99.9% of the pig genome, our analysis represents an almost complete OR gene repertoire from an individual pig genome. We show that S. scrofa has one of the largest OR repertoires, suggesting an expansion of OR genes in the swine genome. A significant number of unique OR genes in the pig genome may suggest the presence of swine specific olfactory stimulation.
Highlights
Insects and animals can recognize surrounding environments by detecting thousands of chemical odorants
Olfaction is a complicated process; it begins in the olfactory epithelium with the specific binding of volatile odorant molecules to dedicated olfactory receptors (ORs) expressed by olfactory sensory neurons (OSNs) [2,3,4,5]
Composition of the pig OR gene repertoire The four motif sequences, GN, MAYDRYVAIC, KAFSTCASH and PMLNPFIY, which are common to mammalian OR genes were used to search the full repertoire of ORs in the pig genome (Figure 1A)
Summary
Insects and animals can recognize surrounding environments by detecting thousands of chemical odorants. Olfaction is a complicated process that begins in the olfactory epithelium with the specific binding of volatile odorant molecules to dedicated olfactory receptors (ORs). Odorant molecules are detected by olfactory receptors (ORs), which are part of the G-proteincoupled receptor superfamily of proteins having seven transmembrane domains. This superfamily was first discovered in rodents about two decades ago [1]. Olfaction is a complicated process; it begins in the olfactory epithelium with the specific binding of volatile odorant molecules to dedicated ORs expressed by olfactory sensory neurons (OSNs) [2,3,4,5]. In spite of the large number of genes that make up the OR subgenome, most OR neurons express a single gene and even just a single allele [1,21]
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