四个绵羊品种BMPR-IB基因CDS区864位点多态性及其产羔数相关性分析

Analysis of Polymorphism at 864 Locus of BMPR-IB Gene CDS Region and Its Relationship with Litter Size in Four Sheep Breeds

为了探索绵羊产羔性状与绵羊BMPR-IB基因多态性位点关系,找寻调控绵羊繁殖力的分子标记,以小尾寒羊(多胎母羊)、湖羊(多胎母羊)、蒙古羊(单,双胎母羊)、和甘肃高山细毛羊(单,双胎母羊)样本为试验材料,运用DNA直接测序及PCR-SSCP技术的方法,对BMPR-IB基因CDS区864位点进行分析。试验羊品种出现3种基因型AA、AB、BB,该基因编码区第846位点发生T>C的突变。湖羊母羊以及小尾寒羊母羊的优势基因型均为AA型,而蒙古羊母羊和甘肃高山细毛羊母羊AB型基因频率略高于AA型。4种绵羊的优势等位基因均为A。小尾寒羊、甘肃高山细毛羊、湖羊三种绵羊x2值和G2值均未达到显著水平(p>0.05),而蒙古羊的x2值和G2值达到显著水平(p<0.05),说明除了蒙古羊其他3种羊均达到Hardy-weinberg平衡状态。四种绵羊的观测值F在BMPR-IB基因中均处于95%置信区间内,且接近于上线。根据各品种间的PIC多态信息含量可知,属于低度多态的是小尾寒羊和湖羊(PIC<0.25),而在蒙古羊和甘肃高山细毛羊信息含量处于中度多态(0.25<PIC<0.5)。显著性检验分析表明:甘肃高山细毛羊与小尾寒羊、湖羊,蒙古羊与小尾寒羊、湖羊中差异呈现显著(p<0.05)。BMPR-IB基因编码区第846位点突变在不同繁殖力母羊群体中分布不同,该位点可以作为绵羊潜在分子标记位点。

To explore the relationship between litter size in sheep and sheep BMPR-IB gene polymorphism, and look for molecular markers to regulate the fecundity of sheep, we took Small Tail Han ewes（multiple births）, Hu ewes（multiple births）, Mongolia ewes（single birth and twins）, and Gansu alpine merino ewes（single birth and twins）samples as test materials to analyze polymorphism at 864 locus of BMPR-IB gene CDS region by DNA sequencing and PCR-SSCP. The results showed that there were three kinds of genotype AA, AB and BB in tested sheep breeds, and T〉C mutation occurred in coding region of 846. AA was the dominant genotype in Small Tail Han ewes and Hu ewes, while AB was the dominant genotype in Mongolia ewes and Gansu alpine merino ews. A was the dominant alleles in all four sheep samples. The x^2 and G2 values of Small Tail Han ewes, Gansu alpine merino ewes and Hu ewes did not reached the significant level（p〉0.05）, but the χ^2 and G2 values of Mongolia ewes reachedthesignificantlevel（p〈0.05）,whichindicatedthatthreeotherewesallfittedwith Hardy-Weinberg equilibrium except Mongolia ewes. The observed value F of four sheep breeds in BMPR-IB gene were in the 95% confidence interval, and closer to the on-line. According to the PIC among different breeds we could get that Small Tail Han sheep and Hu sheep belong to low polymorphism（PIC〉0.25）, while Mongolia sheep and Gansu alpine merino sheep belong to moderate polymorphism（0.25〉PIC〉0.5）. Significant test showed that Gansu alpine merino sheep had significant differences with Small Tail Han sheep and Hu sheep, and Mongolia sheep had significant differences with the other three sheep breeds（p〈0.05）. The mutation occurred in 846 site in BMPR-IB gene coding region distributed differently in ewe groups with different fecundity, which meant that this locus could be considered as a potential molecular marker in sheep.