贵州地方猪品种对氧磷脂酶1基因的多态性研究

本试验以欧洲猪种为参照,研究贵州地方猪对氧磷脂酶1(paraoxonase,PON1)基因的多态性,探讨基因多态性与地方猪的脂肪沉积之间是否存在相关性。研究采用锚定聚合酶链反应技术对香猪、糯谷猪、萝卜猪和可乐猪共138个贵州地方猪品种PON1基因的单核苷酸多态性(single nucleotide polymorphisms,SNP)进行研究。结果表明,猪群PON1基因的163/165位点出现A/T、G/A变异,515位点检测到C/T突变,均以3种基因型存在。经卡方(χ²)检验,贵州地方猪群PON1基因515位点的基因型频率和基因频率与欧洲猪品种间的差异不显著(P>0.05);163/165位点中,贵州地方猪种A等位基因的频率为83.7%,明显高于欧洲猪品种(25.2%)。贵州地方猪品种PON1基因的163/165位点A等位基因占优势,编码的第55位氨基酸为甲硫氨酸(Met55),与脂代谢异常人群的基因型相同;欧洲猪种以B等位基因为主(P<0.01),编码的第55位是亮氨酸(Leu55),与正常人群的基因型一致。以人PON1蛋白的晶体结构为模板,推导出香猪PON1蛋白的三维结构。地方猪PON1基因变异导致的Met55突变可能影响PON1水解酶活性中心的疏水环境,可能使蛋白的水解酶活性下降,使得地方猪品种的脂肪沉积量和肉质不同于欧洲猪种。由此推测,贵州地方猪品种PON1基因163/165位点存在多态性,可能与地方猪种的脂肪沉积和肉质有一定的相关性。

Study on Polymorphism of Paraoxonase 1 Gene in Guizhou Indigenous Pig Breeds

Taking European pig breeds as control, the single nucleotide polymorphisms of paraoxonase (PON1) gene were investigated in Guizhou indigenous pig breeds, including Xiang, Nuogu, Luobo and Kele pig breeds, using allele-specific polymerase chain reaction (AS-PCR) method. The results showed that two nucleotide mutations, A/T and G/A were found out from site 163/165, and one with C/T variation from site 515 of PON1 gene of porcine population. Three genotypes, wild, mutant, and heterozygous, of site 163/165 and 515 were detected from Guizhou indigenous pig breeds and European ones. Frequencies of genotypes and alleles at site 515 in Guizhou pig breeds were not different from that of European pig breeds (P>0.05). But it was significant at site 163/165 of PON1 gene. Allele A was dominant in Guizhou pig breeds with frequency of 83.7%, and were higher than European pig breeds (25.2%). The mutated nucleotides at site 163/165 encoded methionine (Met 55), which was consistent with that of human patients with metabolic syndrome. The wild genotype of PON1 at site 163/165 (allele B), dominated in Europe pig breeds, contained residue leucine (Leu 55) which was corresponding to population without metabolism disorder. Taking the crystal structure of human PON1 protein as template, three-dimensional structure of PON1 from Xiang pig was deduced. The location of Met 55 Leu was next to the calcium binding site in PON1 structure. It had been demonstrated that the hydrolase activity of PON1-M55 decreased and related to the metabolism disorder in human patients, and the polymorphism of PON1 gene was correlated with the meat quality in pig. It suggested that the polymorphism at site 163/165 in PON1 gene might contribute to the improvement of meat quality in Guizhou indigenous pig breeds.