猪SLA-DQA基因外显子4多态性分析

Analyzing Polymorphism of SLA-DQAGene exon4

采用PCR-SSCP及克隆测序技术对大白、长白、杜洛克共210头仔猪SLA-DQA基因第4外显子进行多态性检测,以探讨猪SLA-DQA基因的遗传特性。结果显示:共获得4种等位基因(A、B、C、D),6种基因型(AA、AB、CC、CD、BB、BC)。6种基因型在杜洛克猪中都被检测到,而在大白猪中只检测到AA、AB、CC 3种基因型,在长白猪中未检测到BC基因型。A等位基因和AA基因型的频率在3个群体中最高,为优势基因和优势基因型。对不同SSCP带型的对应片段进行测序分析,共发现3个核苷酸突变位点(5 126 bp A→G,5 158 bp A→T,5 233 bp G→A),其中,5126 bp处A→G导致氨基酸由异亮氨酸变为缬氨酸。经χ2适合性检验,3个猪品种在此位点上都偏离了Hardy-Wein-berg平衡状态(P<0.05)。群体遗传学分析发现:长白猪、大白猪多态信息含量(PIC)分别为0.3233,0.4548,属于中度多态(0.25<PIC<0.5),杜洛克为0.610 1,属于高度多态(PIC>0.5);各基因型在三品种中的分布差异显著。研究结果证实,猪SLA-DQA基因第4外显子具有丰富的遗传多态性。

The polymorphisms of the fourth exon of SLA-DQA gene were detected by PCR-SSCP,aiming to get molecular genetics information about SLA-DQA gene.The results showed that there were 4 alleles and 6 genotypes in Landrace,Large white and Duroc breeds（210 individuals）.6 genotypes（A,AB,CC,CD,BB,BC）was detected in Duroc,AA,AB,CC in Large white,AA,AB,CC,CD,BB in Landrace.alleles A was the predominant allele,AA was the predominant genotype in three breeds.There are 3 mutations in exon 4,（A→G） at 5126bp,（A→T）at 5158bp and（G→A）at 5233bp respectively.（A→G）mutation leads to the changes of encoding amino acid,I→V on protein level.This polymorphic locus in three breeds is deviated from Hardy-Weinberg equilibrium by χ2 test（P 〈0.05）.The polymorphism information content of Landrace and Large white are 0.3233 and 0.4548.respectively indicates moderate polymorphism（0.25〈PIC〈0.5）,Duroc is0.6101 indicates highly polymorphism（PIC〉0.5）,the genotypes are significant among three breeds by χ2 test（P〈 0.01）.It showed that the exon4 of SLA-DQA gene in three breeds had a high level of polymorphism.