柯乐猪XDH基因多态性鉴定及其对繁殖性状的影响

Identification of XDH gene polymorphism and its effects on reproductive traits in Kele pigs

【目的】明确黄嘌呤脱氢酶基因(XDH)单核苷酸多态性(SNP)位点与柯乐猪繁殖性状的关联性,为加速柯乐猪的育种进程提供理论依据。【方法】选取87头健康经产柯乐母猪为研究对象,采用Sanger测序法筛查出XDH基因SNP位点,利用SPSS 22.0中的一般线性模型(GLM)分析SNP位点与柯乐猪繁殖性状指标(产活仔数、初生窝重、平均初生重、断奶仔猪数、断奶窝重及平均断奶重)的关联性,并通过RNAfold web server、ExPASy-ProtParam、NovoPro和SWISS-MODEL等在线软件进行生物信息学分析。【结果】在柯乐猪XDH基因上共筛选获得12个SNPs位点,分别是第33内含子上的g.108047658C>G和g.108047680C>A位点,第34内含子上的g.108048009C>T、g.108048044T>C、g.108048046T>C、g.108048047C>T、g.108048054C>T、g.108048153A>T、g.108048208A>G、g.108048212T>C和g.108048242C>T位点,第34外显子上的g.108047915G>A位点。12个SNPs位点均存在3种基因型,属于中度多态位点(0.25<PIC<0.50);g.108048047C>T、g.108048208A>G、g.108048242C>T、g.108048044T>C、g.108048046T>C和g.108048212T>C位点的基因型分布符合Hardy-Weinberg平衡状态(PHWE>0.05),其余6个SNPs位点的基因型分布则显著偏离Hardy-Weinberg平衡状态(PHWE<0.05)。除g.108047658C>G位点与g.108047680C>A位点、g.108048044T>C位点与g.108048046T>C位点、g.108048046T>C位点与g.108048047C>T位点间存在强连锁不平衡关系外,其余各SNP位点间均不存在强连锁不平衡关系。g.108047658C>G和g.108047915G>A位点对柯乐猪产活仔数的影响达显著水平(P<0.05,下同),g.108047658C>G位点表现为CG基因型个体的产活仔数显著高于GG基因型个体,g.108047915G>A位点表现为AG基因型个体的产活仔数显著高于AA基因型个体。g.108047915G>A位点突变导致柯乐猪XDH基因mRNA二级结构发生改变,最小自由能由-1508.90 kcal/mol上升到-1507.80 kcal/mol;且XDH基因等位基因G的突变还导致其编码蛋白分子式、相对分子量、理论等电点(pI)、不稳定系数及蛋白高级结构发生改变。【结论】柯乐猪XDH基因第33内含子g.108047658C>G位点和第34外显子g.108047915G>A位点对其产活仔数的影响达显著水平,可作为柯乐猪繁殖性状改良的潜在分子辅助标记。

【Objective】To clarify the association between xanthine dehydrogenase gene(XDH)single-nucleotide poly morphism(SNP)and reproductive traits of Kele pigs,and provide theoretical basis for accelerating the breeding process of Kele pigs.【Method】Eighty-seven healthy multiparous Kele sows were selected as the study subjects.The SNP loci of XDH gene were screened by Sanger sequencing method.The association between SNP loci and reproductive shape in dexes(number of live piglets,litter weight at birth,average birth weight,number of weaned piglets,weaning litter weight and average weaning weight)of Kele sows was analyzed by general linear model(GLM)in SPSS 22.0.Bioinfor matics analysis was carried out by RNAfold web server,ExPASy-ProtParam,NovoPro and SWISS-MODEL online soft wares.【Result】Twelve SNPs loci were screened in the XDH gene of Kele pigs,which were g.108047658C>G and g.108047680C>A loci in intron 33,g.108048009C>T,g.108048044T>C,g.108048046T>C,g.108048047C>T,g.108048054C>T g.108048153A>T,g.108048208A>G,g.108048212T>C and g.108048242C>T loci in intron 34,and g.108047915G>A site in exon 34.There are 3 genotypes in all 12 SNPs loci,which were moderately polymorphic loci(0.25<PIC<0.50).The genotype distributions of the loci g.108048047C>T,g.108048208A>G,g.108048242C>T,g.108048044T>C,g.108048046T>C and g.108048212T>C were consistent with Hardy-Weinberg equilibrium(PHWE>0.05),the genotype dis tributions of the remaining 6 SNPs loci deviated significantly from Hardy-Weinberg equilibrium(PHWE<0.05).There was no strong linkage disequilibrium among the other SNPs loci except for the strong linkage disequilibrium between loci g.108047658C>G and g.108047680C>A,between loci g.108048044T>C and g.108048046T>C,between loci g.108048046T>C and g.108048047C>T.g.108047658C>G and g.108047915G>A loci had significant effects on the number of live piglets produced by Kele pigs(P<0.05,the same below),the number of live offspring of individuals with genotype CG at locus g.108047658C>G was significantly higher than that of individuals with genotype GG,and the number of live offspring of individuals with genotype AG at locus g.108047915G>A was significantly higher than that of individuals with genotype AA.Mutation at locus g.108047915G>A changed the mRNA secondary structure of XDH gene,and the minimum free energy increased from-1508.90 kcal/mol to-1507.80 kcal/mol.Mutation of allele G of XDH gene also changed the molecular formula,relative molecular weight,theoretical isoelectric point(pI),instability coefficient and protein higher structure of XDH gene.【Conclusion】g.108047658C>G locus in intron 33 and g.108047915G>A locus in exon 34 of XDH gene in Kele pigs has significant effects on the number of live piglets,which can be used as potential molecular auxiliary markers for improving reproductive traits of Kele pigs.