牦牛脂肪型脂肪酸结合蛋白基因(A-FABP)多态性分析

摘要

脂肪型脂肪酸结合蛋白(A-FABP)属脂肪酸结合蛋白家族(FABPs)成员,参与调节哺乳动物细胞内脂肪浓度,进而影响肌肉内脂肪含量(IMF),因此A-FABP可作为影响IMF的候选基因.本研究采用PCR-SSCP技术检测甘南牦牛、青海牦牛、天祝白牦牛(Bos grunniens)A-FABP基因部分第3内含子、第4外显子及部分3'-UTR区单核苷酸多态性( SNPs),分析检测区域分子遗传特征.结果表明,3类群牦牛引物扩增区域发现5种等位基因A-E；同普通牛A-FABP基因序列比对发现6处SNPs,其中第4外显子区存在c.4222A＞G的同义突变；3'-UTR区c.* 94T＞A只存在于牦牛群体,是其区别于普通牛的遗传特征之一.各等位基因在群体间分布差异较大,其中天祝白牦牛只发现3种等位基因,而青海牦牛发现4种等位基因,这可能与牦牛类群的地域分布及选育程度有关.3类群牦牛A-FABP基因检测位点表现为中度多态(PIC为0.29 ～0.36),有效等位基因数较高,可作为潜在的牦牛肉质性状分子标记位点.%Adipocyte fatty acid-binding protein( A-FABP) ,as a member of the fatty acid binding protein(FAB-Ps) family,play a pivotal role in regulating intracellular fat concentration and then affect intramuscular fat(IMF) in mammalian. So A-FABP was suggested as a candidate gene of IMF in some species of livestock and poultry. In this study, single nucleotide polymorphisms (SNPs) was investigated at A-FABP intron 3,exon4 and 3'-UTR in Gannan yak,Qinghai yak and Tianzhu white yak (Bos grunniens) by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) so as to analyse their molecular genetic characteristics. Five novel SSCP patterns,representing five different alleles A-E were identified in three yak populations. With alignment of the bovine (Bos tauras) and yak A-FABP allelic sequences, six SNPs including a synonymous mutation ( c. 4222A > G) at exon 4 were checked in yak. SNP c. * 94T > A in 3'-UTR of A-FABP which was only detected in yak population represented one of genetic characteristics of yak that differ from the bovine. Alleles distributed disproportionably among three yak populations, such as only alleles A-C were observed in Tianzhu white yak and alleles A-D in Qinghai yak. This may be related to geographical distribution and breeding methods of different yak populations. The mutations in amplified region of yak A-FABP would become a potential locus for genetic markers of meat quality traits of yak as it showed moderate polymorphism with PIC in the range of 0.29 -0.36 and higher effective number of alleles( Ne).