摘要： DRA 基因属BoLA家族Ⅱ类基因,编码Ⅱ类抗原分子的α链,其第2外显子编码的抗原结合区在抗原呈递中发挥重要作用。以天祝白牦牛、大通牦牛、甘南牦牛和普通牛为研究对象,利用PCR-SSCP的方法对BoLA-DRA基因第2外显子及第2内含子多态性进行了检测。结果表明,DRA基因第2外显子区检测到197位T >C和116位G >A突变,对应A、B和C 3种等位基因,PIC值为0.249 ～0.424,为中度多态。第2内含子区发现1个A >G、1个T >C突变和1个C >T突变,对应a、b、c和d 4种等位基因,PIC值为0.389 ～0.515,为中度及高度多态。聚类分析表明,牦牛DRA基因第2外显子区碱基序列与普通牛以及山羊的同源性最高,系统进化情况与它们亲缘关系远近一致。

关键词: 牦牛, 普通牛, DRA基因, PCR-SSCP, 多态性

Abstract: DRA gene,coding α chain of Ⅱ antigen molecules,belongs to the family of BoLA Ⅱ genes.The antigen-binding region coded by exon2 of DRA gene plays an important role in antigen presentation.This study detected the genetic polymorphisms in exon2 and intron2 of BoLA-DRA gene in Tianzhu White yak,Datong yak,Gannan yak and cattle by PCR single-strand conformational polymorphism (SSCP).The results showed that two SNPs,T >C at 197th and G >A at 116th,corresponding to alleles A,B and C were detected,and the polymorphism was moderate level with PIC in the range of 0.249-0.424 in the exon2 of BoLA-DRA.Four mutations,including one T >C,one C >T and one A >G,corresponding to alleles a-d were identified,and moderate or high polymorphism with PIC in the range of 0.389-0.515 was observed in the intron2 of BoLA-DRA in yak and cattle.Deduced nucleotide sequences of BoLA-DRA^* exon2 between yak,bovine and goat were the highest on homology and the phylogenetic distance consistent with their genetic relationship.

Key words: Yak, Bovine, DRA gene, PCR-SSCP, Polymorphism

中图分类号: 

• S823