秦川牛PYGM基因的表达及其遗传变异对胴体和体尺性状的影响

Expression of PYGM gene and relationship between polymorphism of PYGM gene and carcass

【目的】以秦川牛糖原磷酸化酶基因PYGM为候选基因，研究其在秦川牛生长和胴体性状形成中的作用。【方法】以300头（24±2）月龄纯种秦川牛为试验材料，通过DNA测序和PCR—RFLP技术，研究PYGM基因的多态性对秦川牛个体宰前活体质量、胴体质量、体高、体斜长和屠宰率共5个性状的影响；运用RT—PCR技术分析PyGM基因在秦川牛成体和4～5月龄胎牛2个阶段的肺脏、心脏、肝脏、舌、背最长肌及脾脏6种组织中的表达情况。【结果】半定量RT—PCR检测结果显示，PYGM基因在秦川牛胎儿和成年时期的心脏、舌及背最长肌组织中的表达量均显著高于其他组织。并在该基因中筛查到了2个新的单核苷酸变异（sNP）位点，分别为PYGM内含子1上的c—T突变和内含子6中的c—G突变。群体多态性分析结果表明，秦川牛群体在这2个位点处于Hardy-Weinberg平衡状态，并且处于中度多态。2个SNP位点中A和c等位基因为优势等位基因，SNP1位点上AA和AB基因型个体的宰前活体质量和胴体质量显著高于纯合的BB基因型个体；SNP2位点上CC基因型个体的体高显著高于DD基因型个体。【结论1PYGM基因可以作为秦川牛品种改良中与肌肉生长相关的候选基因。

[Objective] This study studied the role of PYGM gene in growth and carcass traits of Qin- chuan cattle. [Method] DNA sequencing and PCR-RFLP technology were used to detect the polymorphism and analyze the relationship between SNPs and slaughter weight, carcass weight, height, slaughter length, and dressing percentage. The expression pattern of PYGM in lung, heart, liver, tongue, back muscle, and spleen of adults and 4--5 months embryos of Qinchuan cattle was investigated using semi-quantitative RT- PCR technology. [Result] Semi-quantitative RT-PCR showed that the expression of PYGM gene in heart, tongue and back muscle tissues was higher than other tissues during both embryo stage and adult phase. Two new SNPs loci were detected：SNP 1 in intron 1 C→T mutation and SNP 2 in intron 6 C→G mutation of PYGM. Group polymorphism analysis showed that the two SNP loci in the group were under Hardy- Weinberg equilibrium and medium polymorphism. Alleles A and C were protogenes on the two SNPs respectively. The slaughter weights and carcass weights of individuals with genotype AA and AB were signif- icantly higher than the individuals with genotype BB on SNP 1. The heights of individuals with CC geno- type were significantly higher than the individuals with DD genotype on SNP 2. [Conclusion] PYGM gene can be used as a candidate gene relating to muscle development in breeding improvement of Qinchuan cattle.