绵羊生物钟基因Cry多态性与产羔数的关联分析

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(0.25T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。

Polymorphisms of Sheep Cry Genes and Their Association with Litter Size

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.175355119 T>C, g.175357583 C>T loci of Cry1 gene and g.74126865 C>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.175355119 T>C and g.74126865 C>T loci. Population genetic analysis showed that g.175355119 T>C and g.175357583 C>T loci were at moderate polymorphism(0.25T locus was at low polymorphism(PIC<0.25) in all sheep breeds. The χ~2 test indicated that g.175355119 T>C locus of all sheep breeds was under Hardy-Weinberg equilibrium(P>0.05), g.175357583 C>T locus of Sunite sheep was under Hardy-Weinberg disequilibrium(P<0.05), g.74126865 C>T locus of Tan sheep and Prairie Tibetan sheep was under HardyWeinberg disequilibrium(P<0.05). Polymorphisms of the 3 SNPs had no significant effect on litter size of Small Tail Han sheep. In conclusion, g.175355119 T>C, g.175357583 C>T loci of Cry1 gene and g.74126865 C>T locus of Cry2 gene are not suitable for litter size selection of Small Tail Han sheep.