小尾寒羊AA-NAT基因克隆及其与繁殖性能的关系

根据牛AA-NAT基因DNA序列和绵羊该基因mRNA序列,设计5对引物(P1～P5),每对引物分别扩增随机选取的8只小尾寒羊,PCR产物克隆测序,序列拼接获得小尾寒羊AA-NAT的DNA序列,总长为2 138 bp。序列比对发现P3的扩增产物中存在C617T的沉默突变。根据获得的小尾寒羊AA-NAT基因的DNA序列设计引物P6,利用PCR-RFLP技术分别在常年发情绵羊品种(小尾寒羊、白杜泊)和季节性发情绵羊品种(滩羊、萨福克和特克塞尔)中检测该位点的多态性。结果发现引物P6扩增片段在滩羊、萨福克和特克塞尔中均检测到CC、CT和TT 3种基因型,在小尾寒羊和白杜泊中只检测到CC和CT 2种基因型;该突变位点不同基因型分布在常年发情绵羊品种和季节性发情绵羊品种间存在显著差异(P<0.05);小尾寒羊CC和CT基因型频率分别为0.24和0.76,CC型母羊平均产羔数比CT型多0.48只(P<0.01)。本研究结果初步表明,AA-NAT基因617位点与绵羊的常年发情可能存在一定关联,C等位基因可能是提高绵羊产羔数的一个潜在有效的标记。

Cloning of AA-NAT gene and its association with reproductive performance in Small Tail Han Sheep

According to Bos taurus AA-NAT DNA sequence and sheep AA-NAT mRNA sequence,five pairs of primers(P1 to P5) were designed to amplify the whole DNA sequence of the AA-NAT gene in eight randomly selected individuals from Small Tail Han sheep.Through DNA sequencing and sequence assembly,a 2 138 bp DNA sequence was obtained.Meanwhile,one nucleotide transition(C617T) was identified in AA-NAT gene of Small Tail Han sheep.According to the obtained DNA sequence of the AA-NAT gene in Small Tail Han sheep,primer P6 was designed to detect C617T mutation of AA-NAT gene in year-round estrous sheep breeds(Small Tail Han and White Dorper sheep) and seasonal estrous sheep breeds(Tan,Suffolk and Texel sheep) by PCR-RFLP.The results showed that three genotypes(CC,CT and TT) were detected in Tan,Suffolk and Texel sheep and only two genotypes(CC and CT) were detected in Small Tail Han and White Dorper sheep.There were significant dif-ferences(P<0.05) in genotype distribution between year-round estrus and seasonal estrus sheep breeds.In Small Tail Han sheep,genotype frequency of CC and CT was 0.24 and 0.76,respectively.And the Small Tail Han ewes with genotype CC had 0.48(P<0.01) lambs more than those with genotype CT.The present study preliminarily indicated that there may be some association between the 617 locus of AA-NAT gene and year-round estrus in sheep,and allele C of AA-NAT gene is a potential marker for improving litter size in sheep.