神经肽Y基因多态性及其与小尾寒羊产羔数的关系

本研究旨在阐明神经肽Y(neuropeptide Y,NPY)基因的多态性及其与小尾寒羊产羔数的关系,为绵羊多羔性的标记辅助选择提供科学依据.采用PCR-SSCP技术检测NPY基因全部3个外显子在小尾寒羊、湖羊、特克塞尔和多赛特羊中的单核苷酸多态性,分析该基因对小尾寒羊多羔性的影响.仅引物P1扩增片段存在多态性,在小尾寒羊中检测到5种基因型,在湖羊和多赛特羊中检测到3种基因型,而在特克塞尔羊中仅枪测到1种基因型;测序分析显示,在小尾寒羊中存在CR、TR和TW3种等位基因,在湖羊和多赛特羊中存在CR和TR 2种等位基因,而在特克塞尔中仅存在CR 1种等位基因.TR与CR相比在绵羊NPY基因编码区第93 bp处发生了1个C→T的单碱基突变;TW与CR相比除发生C93T的单碱基突变外,还在130和131 bp发生了GA塞AT的双碱基突变,该突变引起绵羊NPY成熟肽第16位氨基酸由天冬氨酸变为异亮氨酸.对于多态位点C/T,小尾寒羊3种基因型之间产羔数差异均不显著(P＞0.05).对于多态位点GA/AT,RW型小尾寒羊产羔数平均比RR型的多0.56只(P＜0.05).在小尾寒羊5种复合基因型中,TTRW和CTRW型小尾寒羊产羔数差异不显著(P＞0.05);TTRR、CTRR和CCRR型小尾寒羊产羔数差异也不显著(P＞0.05);TTRW和CTRW型小尾寒羊产羔数均显著高于其余3种基因型(P＜0.05).本研究结果初步表明NPY基因GA/AT突变位点的W等位基因是提高绵羊产羔数的1个潜在有效的DNA标记.

Polymorphism of Neuropeptide Y Gene and Its Relationship with Litter Size of Small Tail Han Sheep

The objectives of the present study were to elucidate the polymorphism of ovine neuropeptide Y (NPY) gene and its relationship with litter size of Small Tail Han sheep, and to provide a scientific basis for marker-assisted selection for prolificacy in sheep. The NPY gene was studied as a candidate gene for prolificacy in some sheep breeds. Single nucleotide polymorphisms (SNPs) of all three exons (exon 1, 2 and 3) of NPY gene were detected in Small Tail Han, Hu, Texel and Dorset sheep by polymerase chain reaction-single strand conformation polymorphism.Only the product amplified by primer P1 displayed polymorphism. Five genotypes were detected in Small Tail Hart sheep, three genotypes in Hu and Dorset sheep, but only one genotype in Texel sheep. Sequencing results revealed that there were three alleles (CR, TR and TW) in Small Tail Han sheep, two alleles (CR and TR) in Hu and Dorset sheep, only one allele (CR) in Texel sheep. Compared with CR allele, there was one single nucleotide mutation (C→T) at 93 bp position of coding region of NPY gene in the TR allele. Compared with CR allele, besides C93T mutation, there was one double nucleotide mutation (GA→AT) at 130 and 131 bp position of coding region of NPY gene in the TW allele. This mutation caused an Asp→Ile replacement at position 16 of amino acid sequence of sheep NPY mature peptide. For C/T polymorphic site, the differences of the litter size between three genotypes were non-significant in Small Tail Hart sheep (P＞0.05). For GA/AT polymorphic site, the ewes with genotype RW had 0. 56 (P＜0.05)lambs more than those with genotype RR in Small Tail Han sheep. In the five combined genotypes of Small Tail Han sheep, the difference of the litter size between TTRW and CTRW genotypes was non-significant (P＞0.05), the differences of the litter size between TTRR, CTRR and CCRR genotypes were non-significant (P＞0. 05), least squares means of litter size for TTRW and CTRW genotypes were significantly higher than those for the other genotypes (P＜0.05).These results preliminarily indicated that allele W of GA/AT polymorphic site of NPY gene is a potential DNA marker for improving litter size in sheep.