5个猪种HSD17B12基因结构变异SV225的多态性研究

Polymorphism of structural variation SV225 in the HSD17B12 gene of five pig breeds

基于香猪基因组重测序结果,发现HSD17B12基因内含子3中存在一个254 bp的结构变异位点,命名为SV225。为探索SV225在不同猪群体间多态性分布以及基因型与香猪产仔数的关系,选取4个贵州地方猪种（香猪、柯乐猪、江口萝卜猪、黔北黑猪）和1个欧洲猪种（大白猪）为动物样本,利用PCR检测5个猪种中结构变异SV225的分布频率。结果显示,4个贵州地方猪种中均检测到3种基因型：插入型Ⅱ,杂合型DI与缺失型DD,SV225多态性丰富,大白猪仅检测到Ⅱ型。4个贵州地方猪群相比,香猪和柯乐猪的D等位基因占优势,江口萝卜猪和黔北黑猪中Ⅰ等位基因比例更高。经卡方检验,香猪、柯乐猪的D等位基因频率显著高于江口萝卜猪和黔北黑猪（P〈0.01）,且4个贵州地方猪种的D等位基因均显著高于大白猪（P〈0.01）。分析3种基因型与香猪产仔数的关系,发现Ⅱ型个体的第三胎平均产仔数比DI型多2.25头（P〈0.01）。本研究结果提示HSD17B12基因中的结构变异SV225与地方猪的产仔数可能存在一定的联系。

A structural variation（ SV） site,named SV225 here,of 254 bp in length was identified from the intron 3 of the HSD17 B12 gene based on the re-sequencing data of the Xiang pig. To investigate the polymorphism of SV225 and the relationship between genotypes and litter size of the Xiang pig,the genotype distribution of SV225 was detected by PCR among five pig breeds,which were four Guizhou local pig breeds of the Xiang pig,the Kele pig,the Jiangkouluobo pig and the Qianbeihei pig,and one European breed,the Yorkshire pig. The results demonstrated that three genotypes,genotypes II,DI and DD,were detected in the local breeds,implying a high polymorphism of SV225. However,only one genotype,II,was found in the Yorkshire pig. In the four Guizhou local pig populations,the allele D was predominant in the Xiang pig and the Kele pig,and allele I was dominant in the Jiangkou Luobo and Qianbeihei pigs. The chi-square test showed that the frequencies of allele D in the Xiang and Kele pigs were higher than that in the Jiangkouluobo and Qianbeihei pigs（ P〈0. 01）,and it was much higher in the four local breeds than that in Yorkshire pig（ P〈0. 01）. Analysis of the relationship between the three genotypes and litter size of the Xiang pig revealed that the third litter size of the type II sow was 2. 25 piglets more than that of the type DI one（ P〈0. 01）.The present study suggested that the structural variation of SV225 in the HSD17 B12 gene might be related to the litter size of local pigs.