猪IGF-Ⅰ基因的一个遗传多态性及其遗传效应分析

One Genetic Polymorphisms and Genetic Effects of IGF-Ⅰ Gene in Pigs

采用PCR-SSCP方法对长白猪(87头)、大白猪(79头)和马身猪(102头)的胰岛素样生长因子-Ⅰ(IGF-Ⅰ)基因外显子3和外显子4分别进行单核苷酸多态性分析.发现外显子3上有多态性,且存在3种基因型(AA、AB、BB).统计结果表明,3种基因型在各品种中的分布不一致,多重比较差异极显著(P<0.01).固定效应模型分析结果表明,背膘厚基因型间差异显著(P<0.05),而初生重、断奶重和6月龄重基因型间差异不显著(P>0.05).最小二乘分析结果表明,BB基因型与其它2种基因型比较有较大的初生重,同AA和AB型比较差异极显著(P<0.01),3种基因型在初生重的大小排列顺序为AA<AB<BB;BB基因型与AA基因型比较有较小的背膘厚,且差异极显著(P<0.01).因此,推测IGF-Ⅰ基因对个体的初生重和胴体瘦肉率存在一定的影响.选择带有B等位基因的个体,有望提高个体的初生重和胴体的瘦肉率.

Single nucleotide polymorphisms of 87 Landrace pigs, 78 large white pigs and 102 Mashen pigs at exon3 and exon4 of IGF-I gene were tested by PCR-SSCP. One polymorphism was found at exon3, three genotypes exist （ AA, AB, BB ）. Results of x^2 test showed that frequencies of genotypes in different breeds differ significantly from each other （P 〈 0.01 ）. Based on the fixed effect model, significant differences were found among IGF- I genotypes on backfat thickness, while no significant difference existed on birth weight, weaning weight and 6-month body weight; Using least square analysis, individuals of the BB genotype had significantly higher （P 〈 0.01） birth weight than those of AA and AB genotypes, with the order being AA 〈 AB 〈 BB. The pigs of BB genotype had significantly lower （ P 〈 0.01） backfat thickness than those of AA genotype. These results suggest that IGF-Ⅰ gene has significant effects on individual birth weight and backfat thickness, and selection of the B allele is favored in terms of birth weight and backfat thickness.