绵羊生物钟基因Cry多态性与产羔数的关联分析

Polymorphisms of Sheep Cry Genes and Their Association with Litter Size

为探究绵羊Cry1基因g.175355119T>C、g.175357583C>T位点与Cry2基因g.74126865C>T位点多态性与绵羊产羔数之间的关系,本实验利用全基因组重测序结合Sequenom MassARRAY?SNP技术对常年发情绵羊品种(小尾寒羊、湖羊和策勒黑羊)和季节性发情绵羊品种(滩羊、苏尼特羊和草原型藏羊)Cry1基因与Cry2基因共3个多态位点多态性进行检测,并与小尾寒羊产羔数进行关联分析。结果表明:Cry1基因g.175355119T>C位点存在CC、CT和TT 3种基因型,g.175357583C>T位点存在TT、TC和CC 3种基因型;Cry2基因g.74126865C>T位点存在CC、CT和TT 3种基因型。群体遗传学分析表明,Cry1基因g.175355119T>C位点与Cry2基因g.74126865C>T位点的基因型频率和等位基因频率在2种发情模式绵羊品种间的差异均达到极显著水平。在6个绵羊品种中,Cry1基因g.175355119T>C位点与g.175357583C>T位点均表现为中度多态(0.25<PIC<0.5),Cry2基因g.74126865C>T位点均表现为低度多态(PIC<0.25)。卡方适合性检验表明,Cry1基因g.175355119T>C位点在6个绵羊品种中均处于哈代温伯格平衡状态(P>0.05),g.175357583C>T位点在苏尼特羊中处于哈代温伯格不平衡状态(P<0.05),Cry2基因g.74126865C>T位点在滩羊和草原型藏羊中处于哈代温伯格不平衡状态(P<0.05)。关联分析表明,3个多态位点与小尾寒羊第1、第2以及第3胎产羔数均无显著关联(P>0.05)。综上,Cry1基因g.175355119T>C、g.175357583C>T位点与Cry2基因g.74126865C>T位点均不适用于小尾寒羊产羔数选育。

To elucidate the association between Cry genes polymorphism and litter size in sheep.Year-round estrous sheep breeds(Small Tail Han,Cele Black and Hu sheep)and seasonal estrous sheep breeds(Tan,Sunite and Prairie Tibetan sheep)were selected and Sequenom MassARRAY■SNP assay was applied to genotype g.175355119T>C,g.175357583C>T loci of Cry1 gene and g.74126865C>T locus of Cry2 gene.Then the association was analyzed between Cry1/2 and litter size in Small Tail Han sheep.The result of genotyping showed that three genotypes were found at 3 loci in both year-round estrous and seasonal estrous sheep,both genotype frequency and allele frequency were high significantly different between yearround estrous and seasonal estrous sheep(P<0.01)in g.175355119T>C and g.74126865C>T loci.Population genetic analysis showed that g.175355119T>C and g.175357583C>T loci were at moderate polymorphism(0.25<PIC<0.5)in all sheep breeds,g.74126865C>T locus was at low polymorphism(PIC<0.25)in all sheep breeds.Theχ2 test indicated that g.175355119T>C locus of all sheep breeds was under Hardy-Weinberg equilibrium(P>0.05),g.175357583C>T locus of Sunite sheep was under Hardy-Weinberg disequilibrium(P<0.05),g.74126865C>T locus of Tan sheep and Prairie Tibetan sheep was under Hardy-Weinberg disequilibrium(P<0.05).Polymorphisms of the 3 SNPs had no significant effect on litter size of Small Tail Han sheep.In conclusion,g.175355119T>C,g.175357583C>T loci of Cry1 gene and g.74126865C>T locus of Cry2 gene are not suitable for litter size selection of Small Tail Han sheep.