【作者】 宋跃芬；

【导师】 刘娣；

【作者基本信息】 东北农业大学 ， 动物遗传育种与繁殖， 2002， 硕士

【摘要】 肥胖基因(ob)由3个外显子和2个内含子组成，ob基因产物—leptin是调节体内脂肪含量和体重的重要信号因子，其有可能是影响猪生长和脂肪沉积的数量性状位点，所以对它的分析将在猪的育种中有重要理论意义和实际意义。 本研究利用PCR-SSCP(PCR-Single Stand Conformation Polymorphism)技术，以大白猪，双肌臀大白猪、长白猪、杜洛克、民猪、三江白猪、野家杂种猪、野猪8个不同的猪品种(系)为研究对象，根据Genebank上猪ob基因序列设计了3对引物，对猪ob基因的第1、2外显子进行PCR扩增，PAGE凝胶电泳，并对有多态性的纯合片段进行克隆测序。基因型检测结果为：民猪均为BB型，双肌臀大白猪均为AA型，其他6个品种均有AA、BB、AB 3种类型；A基因在ob基因第3469bp，即第2外显子的69碱基处发生一个点突变：T→C，该突变属于沉默突变。 经试验统计和计算各基因型频率和基因频率表明：民猪、三江白猪、杜洛克、大白猪、长白猪、双肌臀大白猪、野猪和野家杂种猪的A基因频率除野猪、野家杂种猪外呈现依次上升趋势，即0.000→0.577→0.738→0.798→0.809→1.000，而品种瘦肉率也完全按此顺序呈上升趋势；民猪是进行肥猪育种所形成的品种，其A基因频率下降，所检测40个个体中A基因频率达到0，三江白猪、杜洛克、大白猪、长白猪是以追求高瘦肉率为重要的育种目标之一，经长期选育而形成的品种，A基因频率呈现升高趋势，并随品种瘦肉率增加而升高，野猪和野家杂种猪的A基因频率基本在进行肥猪育种和瘦肉猪育种的品种中间，双肌臀大白猪A基因频率为1。本研究得出趋势性结论：A基因频率一方面与瘦肉率呈正相关、与双肌臀性状相关，一方面与育种选择方向有关。所以在猪育种中可以把ob基因的A基因作为高瘦肉率的选择标记。 利用PCR-SSCP技术检测ob基因的基因型，使试验操作简单，灵敏度提高，可以在标记辅助育种研究中广泛应用。更多还原

【Abstract】 The lean meat percentage is one of’the important traits in pig breeding. Obese gene,which contains three exons and two introns,is a newly cloned gene,whose product-leptin functions as factor regulating fat content and body weight. The ob gene may be the major gene that influences the fat deposition and lean meat percentage. The study on it will have theoretical and practical significance.In this study,we analyzed the polymorphism of porcine ob cDNA among different breeds including Landrace,Duroc,Min pig,Yorkshire,double-muscled Yorkshire,Sanjiang pig,Wild boar and Cross bred pig by PCR-SSCP. We designed three pairs of primers according to the ob cDNA sequence obtained from Genbank database to amplify the first two exons and analyze them by SSCP. We have found a T to C transversion in the second exon. So there were three genotypes in different porcine breeds Which were named AA,AB and BB respectively. In Min pig,there were only genotype of BB,while no allele B was detected in double-muscled Yorkshire;in other breeds three genotypes all existed. And the frequencies of these genotypes had difference among breeds.In breeds of Min pig,Sanjiang pig,Duroc,Yorkshire Landrace,double-muscled Yorkshire. The frequencies of A gene increased progressively,and the lean meat percentage in these breeds also rised in this order. Sanjiang pig,Duroc,Yorkshire pig,Landrace were all bred to improve lean meat percentage and the double-muscled Yorkshire had the highest percentage,while Min pig was bred for fat mass. A gene frequencies of wild boar and cross bred pig was between that of fat pigs and lean meat pigs. There was a trend that the distribution of A gene is highly relative to the lean meat percentage on the one hand,on the other hand it was linked to selected direction. So the allele A could be used as. selective marker of lean meat percentage in pig breeding.更多还原