牦牛和普通牛 BoLA-DRA* Exon2-intron2多态性分析

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。%DRA gene,coding αchain of Ⅱ antigen molecules,belongs to the family of BoLA Ⅱ genes.The an-tigen-binding region coded by exon2 of DRA gene plays an important role in antigen presentation.This study detec-ted 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 1 97th and G >A at 1 1 6th,corresponding to alleles A,B and C were detected,and the polymorphism was moder-ate 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 -0.51 5 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.