牦牛IGF2内含子8的遗传多态性及其遗传效应分析

Genetic polymorphisms and genetic effects of IGF2 gene intron8 in yak

【目的】研究牦牛胰岛素样生长因子2(IGF2)基因内含子8的多态性与生长发育性状的相关性,探索其对开展牦牛分子育种的影响。【方法】以天祝白牦牛、甘南牦牛、大通牦牛、青海高原牦牛和新疆牦牛为供试动物,采集牦牛血样,提取其DNA,采用PCR-SSCP方法检测牦牛IGF2基因内含子8的多态性,并分析其对体质量、体高、胸围和体长的遗传效应。【结果】扩增到牦牛IGF2基因内含子8的部分序列,其长度为438bp,存在AA、AB、BB3种基因型,其中AA型是由BB型330位G→C和358位A→G转换造成的。除新疆牦牛以外,以上3种基因型在其他牦牛群体中均处于Hardy-Weinberg平衡状态。AA和AB基因型个体体质量极显著高于BB基因型个体(P<0.01),AA与BB基因型个体在体高、体长和胸围性状上差异不显著。【结论】IGF2基因有可能作为体质量性状的候选基因用于标记辅助选择,且其有不依赖于骨骼增长而增加体质量的作用机制。

[Objective] The research studied the polymorphism of IGF2 gene and the association of polymorphism with growth and development traits to improve performance and breeding of yak. [Method] Single nucleotide polymorphisms of the intron8 of the Yak IGF2 gene were tested using PCR-SSCP. Genetic effects of the IGF2 gene on weight, stature,chest circumference and stem oblique length were analyzed. [Result] On the mainstay of the published DNA sequence（NW 001494548） of the bovine IGF2 gene,pairs of primers were designed,and two polymorphisms,three genotypes were found in the PCR products amplified with intron8 primers. Transition of G→C at 330 site and A→G at 358 site of intron8 was detected for wild type by sequencing the homozygotes. The results showed that it didn＇t meet the equilibrium of Hardy- Weinberg only in Xinjiang Yaks. Using least square analysis,it showed that individuals of AA and BB genotypes had significantly higher（P〈0. 01） weight than BB genotype, but had no difference on the other growth traits. [Conclusion] IGF2 has a mechanism of action which increases the weight without dependence on the growth of the bones.