6个绵羊群体BMP15、GDF9基因多态性分析

本研究旨在检测新吉细毛羊、中国美利奴羊（无角型）、东北细毛羊、杜×寒杂交羊（F1）、杜×寒杂交羊（F3）、白头杜泊羊6个绵羊群体骨形态发生蛋白15（bone morphogenetic protein 15，BMP15）、生长分化因子9（growth differentiation factor 9，GDF9）基因的多态性，为绵羊繁殖力的标记辅助选择和育种提供理论依据。以6个绵羊群体共378只个体为研究对象，利用PCR-SSCP技术检测BMP15、GDF9基因多态性；用DNAStar软件与I-TASSER软件预测蛋白质二级结构和三级结构；计算基因频率、基因型频率、Hardy-Weinberg平衡、杂合度（He）、纯合度（Ho）、有效等位基因数（Ne）和多态信息含量（PIC）。运用GraphPad Prism 6软件对新吉细毛羊群体BMP15基因多态性与产羔数进行相关性分析。结果显示，BMP15基因P1引物扩增片段存在多态性，6个群体共呈现3种基因型：AA、AC、CC，该突变为BMP15基因外显子1上58-60 bp 3个碱基（CTT）缺失，新吉细毛羊、杜×寒杂交羊（F3）、白头杜泊羊的χ²值均达到显著水平，处于Hardy-Weinberg不平衡状态，不同基因型间新吉细毛羊平均产羔数差异均不显著（P>0.05）；GDF9基因P2引物扩增片段存在多态性，6个群体共呈现3种基因型：DD、DE、EE，其中新吉细毛羊仅有1种基因型：DD，该突变为GDF9基因外显子2上477 bp处T→C的转换，该突变未导致氨基酸的改变，除新吉细毛羊外其余5个群体χ²值均未达到显著水平，处于Hardy-Weinberg平衡状态，说明GDF9基因T477C突变不能作为新吉细毛羊多胎性状遗传标记位点。

Genetic Polymorphism Analysis of BMP15 and GDF9 Genes in Six Sheep Breeds

This study was aimed to detect the gene polymorphism of bone morphogenetic protein 15(BMP15) and growth differentiation factor 9 (GDF9) genes in Xinji Fine-wool sheep,Northeast Fine-wool sheep,Chinese Merino(Mulley type) sheep,Dorper×Han crossbred sheep (F1),Dorper×Han crossbred sheep (F3) and White Dorper sheep,which would provide a theoretical basis for marker-assisted selection and breeding for prolificacy in sheep.A total of 378 individuals from six sheep breeds were used to study the polymorphism of BMP15 and GDF9 genes by PCR-SSCP.Secondary structure and tertiary structure of proteins were predicted using DNAStar and I-TASSER.Gene frequency,genotype frequency,Hardy-Weinberg equilibrium,heterozygosity (He),homozygous (Ho),number of effective alleles (Ne) and polymorphic information content (PIC) were calculated.The correlation was analyzed between BMP15 gene polymorphism and litter size in Xinji Fine-wool sheep by GraphPad Prism 6 software.The results showed that the polymorphism was found in P1 primer amplification fragment of BMP15 gene,there were three genotypes of AA,AC and CC in six breeds.This mutation was a 58-60 bp (CTT) deletion in exon 1 of BMP15 gene.According to χ² test,Xinji Fine-wool sheep,Dorper×Han crossbred sheep (F3) and White Dorper sheep were not in Hardy-Weinberg equilibrium.There was no significant difference in the average litter size of different genotypes in Xinji Fine-wool sheep (P>0.05).The polymorphism was found in P2 primer amplification fragment of GDF9 gene.There were three genotypes of DD,DE and EE in six breeds,and there were only one genotype in Xinji Fine-wool sheep.This mutation was a T→C conversion at 477 bp on GDF9 gene exon 2 which didn't lead to amino acid change.According to χ² test,five breeds (except for Xinji Fine-wool sheep) were in Hardy-Weinberg equilibrium.The results indicated that the GDF9 gene T477C mutation couldn't be used as a genetic marker for multiple fetal traits in Xinji Fine-wool sheep.