旨在研究秦川牛脂肪酸转位酶基因(Cluster of differentiation 36,CD36)的多态性及其对秦川牛肉用性状的影响,以探索改善秦川牛肉用性状的分子育种方法。本研究选取288头同等饲养条件下的24月龄健康秦川牛母牛,采用DNA测序技术检测了CD36基因的多态性,并结合PCR-RFLP技术对所发现的多态位点进行基因型分型,然后将不同基因型与秦川牛肉用性状(背膘厚、眼肌面积、眼肌深度和肌内脂肪含量)进行关联性分析。结果表明,在CD36基因上发现4个多态位点,分别命名为SV1、SV2、SV3和SV4。连锁不平衡和单倍型分析表明,SV1-SV2为连锁位点,与SV3为强连锁,SV4与其他3个位点均为弱连锁,单倍型ITA属于优势单倍型(频率为60.4%)。关联分析结果表明,除SV4在眼肌深度指标中存在显著性差异外,单个多态位点的基因型之间和不同多态位点的组合基因型之间均在肌内脂肪含量指标中存在显著性或极显著性差异。其中,IITTAG型个体在肌内脂肪含量指标中显著低于IWTCAA型个体(P<0.05),极显著低于WWCCAA型个体(P<0.01)。结果提示,CD36基因对秦川牛肉用性状有显著的影响,可通过人工选择降低群体中IITTAG型个体的比例以改善肉用性状。
Silent information regulator 2 （Sir2） proteins, or sirtuins, are nicotine adenine dinucleotide （NAD）-dependent deacetylases that connect metabolism with longevity in lower organisms. In mammals, there are seven Sir2 homologs, namely, silent information regulators （SIRT1-7）. SIRT4 and SIRT7 genes play a crucial role in regulating lipid metabolism, cellular growth and metabolism. This suggests that they are potential candidate genes for affecting body size and meat quality traits in animals. Hence, this study aimed to detect genetic variations of both SIRT4 and SIRT7 bovine genes in Qinchuan cattle, and to evaluate the effect of these variations on economically important body size and meat quality traits. Expression analysis using quantitative real-time PCR （qPCR） indicated that SIRT4 and SIRT7 were broadly expressed in all thirteen studied tissues. The expression of SIRT4 was higher in liver, muscle, and in subcutaneous fat tissue. In the case of SIRT7, the expression was higher in lung, abomasum, and subcutaneous fat. Using DNAsequencing, a total of three single nucleotide polymorphisms （SNPs） were identified within SIRT4 and SIRT7 genes in 468 Qinchuan cattle. These included one novel SNP within 3＇ untranslated regions （UTR） of SIRT4 （SNP1： g. 13915A〉G） and two novel synonymous substitutions in SIRT7 （SNP2： g.3587C〉T and SNP3： g.3793T〉C）. Statistical analyses indicated that all three SNPs could significantly influence some body size and meat quality traits in Qinchuan cattle. These novel findings will provide a background for application of bovine SIRT4 and SIRT7 genes in the selection program of Chinese cattle.
