猪IGF2基因外显子4b的遗传多态性及其遗传效应

Genetic Polymorphisms and Genetic Effects of exon4b of IGF2 Gene in Pigs

采用PCR-SSCP方法检测猪胰岛素样生长因子2(insulin-like growth factor 2,IGF2)基因外显子4b的多态性,并分析其对初生重、断奶重、6月龄重和背膘厚的遗传效应。根据猪IGF2基因的DNA序列(AY044828)设计引物,在exon4b上发现了一个多态性位点,并对纯合子进行测序,发现13位C→A转换,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,长白猪与大白猪比较,莱芜猪与大薄莲猪比较,沂蒙黑猪和里岔黑猪比较差异不显著(P>0.05);其他猪种间基因型分布的差异均显著(P<0.05)。固定效应模型分析结果表明,初生重,断奶重和背膘厚基因型间差异显著(P<0.05),而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基因型个体同AA和AB、基因型个体比较初生重和断奶重的差异显著(P<0.05),3种基因型在初生重和断奶重的大小排列顺序为AA>AB>BB;AA基因型个体同AB和BB基因型个体比较背膘厚的差异显著(P<0.05),3种基因型在背膘厚的大小排列顺序为BB>AB>AA。因此,推测IGF2基因对个体的生长速度和胴体瘦肉率存在一定的影响,将IGF2基因应用于猪育种过程中的标记辅助选择可以加快猪的育种进程。

Single-nucleotide polymorphisms of the exon4b of the porcine IGF2 gene were tested using PCR-SSCP.Genetic effects of the IGF2 gene on the Birth Weight,the Weaning Weight,the Weight at the six-month and the backfat thickness were analyzed.On the basis of the published DNA sequence（AY044828）of the porcine IGF2 gene,primers were designed,and one polymorphism was found in the exon4b.C→A transition at 13 site of exon4b was detected by sequencing the homozygotes.Three genotypes existed.The results show that：firstly,the genotype distribution wasn＇t in consistent among the different pig breeds.No significant differences（P〉0.05）were found for the genotype distribution while the Landrace compared with the Large White,the Laiwu compared with the Dapuliang,the Yimeng compared with the Licha Black pig breeds,whereas significant differences（P〈0.05）were found among the other tested pig breeds for the genotype distribution.Secondly,on the basis of the fixed effect model,significant differences（P〈0.05）were found in the Birth weight,the Weaning Weight and the Backfat thickness,whereas no significant differences（P〉0.05）existed in the Weight at the six-month.Thirdly,using least square analysis,it was shown that individuals of the BB genotype have significantly lower（P〈0.05）birth weight and weaning weight than those of AA and AB genotypes,with the order being AA〉AB〉BB;Individuals of the AA genotype have significantly lower（P〈0.05）backfat thickness than those of AB and BB genotypes,with the order being BB〉AB〉AA.These results suggest that IGF2 gene has significant effects on individual birth weight and backfat thickness.The IGF2 gene can be used in marker-assisted selection to accelerate the breeding progress.