Uncoupling protein-1 gene (UCP1) plays an important role in the regulation of thermogenesis, energy expenditure, and protection against oxidative stress. In this study, six separate UCP1 regions: region-1 and region-2 (two parts of the promoter), region-3 and region-4 (two parts of intron 1), region-5 (spanning part of intron 5 and part of exon 6), and region-6 (spanning part of exon 6 and part of the 3'-UTR) from a variety of sheep breeds, were analysed using polymerase chain reaction-single-stranded conformational polymorphism (PCR-SSCP) analyses. In total, 30 single nucleotide polymorphisms (SNPs) were detected. Of these, 14 were located in the promoter, eight were found in intron 1, six were found in intron 5, and one was found in the 3'-UTR. One substitution in exon 6 (c.910A/G) would putatively result in an amino acid change (p.Thr304Ala). Twenty-eight novel SNPs and nine new haplotypes spanning region-2 to region-5 were identified. Of these nine haplotypes, five were common (B₂-A₅, C₂-A₅, C₂-C₅, A₂-A₅, and A₂-B₅) and four were rare (C₂-B₅, A₂-C₅, B₂-C₅, and B₂-B₅) in the sheep investigated. Of the five common haplotypes found in 314 New Zealand Romney sheep for which growth and carcass trait data were available, the presence of A₂-B₅ was associated with decreased hot carcass weight (HCW) and loin lean-meat yield (p = 0.006, p = 0.032, respectively), and the presence of C₂-C₅ was associated with a decreased proportion of leg lean-meat yield (p = 0.047) in the carcasses. No associations were found with growth traits. These results confirm that ovine UCP1 is a variable gene and may have value as a genetic marker for sheep breeding.
Keywords: carcass traits; haplotype; sheep; uncoupling protein-1 gene (UCP1); variation.