西藏牦牛IGF2基因内含子8遗传多态性及其遗传效应分析

Genetic Polymorphisms and Genetic Effects of IGF2 Gene Intron 8 in Tibet Yak

以胰岛素样生长因子2(IGF2)基因内含子8作为影响西藏牦牛生长性状的候选基因,研究并分析其与生长性状的相关性,以期利用分子标记辅助选择等育种措施为我国西藏高山牦牛进行种质资源保种选育提供理论根据。本研究采用PCR产物直接测序法对帕里牦牛、申扎牦牛、斯布牦牛和类乌齐牦牛4个品种(类群)共151个样本的胰岛素生长因子2(IGF2)基因内含子8部分序列进行了单核苷酸多态性研究,并分析候选基因不同基因型与体重、体高、体斜长、胸围和管围等生长性状的相关性。结果表明:①西藏牦牛IGF2基因内含子8部分序列长度为412 bp,在帕里牦牛和申扎牦牛中发现AA、AB、BB 3种基因型,与AA型相比,BB型在307位发生G→C转换,335位发生A→G突变;②对标记基因型生长发育指标(体高、体斜长、胸围、管围、体重)进行差异显著性检验,帕里牦牛BB基因型个体的体重显著高于AB、AA基因型个体(P<0.05),申扎牦牛BB基因型个体的体重极显著高于AA基因型个体(P<0.01),显著高于AB基因型个体,而在斯布牦牛和类乌齐牦牛中未发现有BB基因型个体。③4个牦牛品种(类群)的BB与AB、AA基因型个体在体高、体斜长、胸围和管围性状上差异不显著;④适合性检验表明3种基因型在西藏牦牛群体中均处于Hardy-Weinberg平衡状态。由此可得,IGF2基因可能在不依靠骨骼增长的条件下而增加体重量,可作为辅助选择来标记体重量的候选基因。

The insulin-like growth factor 2 （IGF2） gene intron 8 as candidate genes influence Tibet yak growth traits used to study and ana- lyze its correlation with growth traits, in order to use the molecular marker assisted selection breeding measures for our country mountain in Tibet yak breeding germplasm resource storage were provided according to the theory. This experiment adopts the method of PCR product di- rect sequencing on yak in four varieties（Pali yak,Shenzha yak,Sibu yak and Leiwuqi yak） of a total of 151 samples of insulin growth factor 2 （ IGF2 ） gene intron 8 partial sequence on the single nucleotide polymorphisms research, and analysis on body weight, body height, body length, chest circumference and genetic effect of tube is surrounded. Results showed that ： （i） Tibet yak IGF2 gene intron 8 partial sequence length of 412 bp, and found in the Pali yak and Shenzha yak to AA, AB, and BB three genotypes, thereinto BB is composed 307 G--＋C and 335 A---~G mutual transformation. （ii）Type of marker gene growth index （body height, body length, chest cirreumference, pipe circumfer- ence, body weight） for difference significance test and Pali yak BB genotype individual weight significantly higher amount of AB, AA geno- type individuals （P 〈 0.05 ）, Shenzha yak BB genotype individual weight significantly higher than that of AA genotype individuals （P 〈 0. 01 ）, significantly higher than AB genotype individuals, and in Sibu yak and Leiwuqi yak groups, the BB genotype individual has not been found. Four varieties of yak （groups） BB and AB, AA genotype individuals in body height, body length, chest circumference and tube a- round the character difference was not significant. （iii） Fitness tests three genotypos in Tibet yak populations are in Hardy-Weinberg equilib- rium state. It can be concluded that IGF2 gene may not rely on bone growth and increase the weight of mechanism, the future can be as a marker assisted selection to the weight of candidate genes.