绵羊B4GALNT2和ESR1基因多态性及其与产羔数的关联分析

为探究影响宁夏地区优质肉羊培育中多羔性状的候选位点，试验以杜泊羊、滩寒杂交羊、杂一代、杂二代和横交一代5个绵羊群体为研究对象，采用飞行质谱技术对5个绵羊群体β-1，4-N-乙酰半乳糖胺转移酶2（beta-1，4-N-acetyl-galactosaminyl transferase 2，B4GALNT2）基因g.36933082 G>A和g.36946470 G>A位点以及雌激素受体1（estrogen receptor 1，ESR1）基因g.75378892 A>T位点进行多态性检测，并与绵羊产羔数进行关联分析；应用生物信息学在线软件分析B4GALNT2和ESR1基因突变前后蛋白质的二级结构和三级结构。结果显示，B4GALNT2基因的g.36933082 G>A和g.36946470 G>A位点均存在3种基因型：AA、AG和GG，且GG基因型均为优势基因型；ESR1基因的g.75378892 A>T位点存在3种基因型：AA、TA和TT，且AA基因型为优势基因型。g.36933082 G>A和g.36946470 G>A位点在5个绵羊群体中均表现为低度多态（PIC<0.25），g.75378892 A>T位点在5个绵羊群体中均表现为中度多态（0.25<PIC<0.5）；3个位点在5个绵羊群体中均处于哈代-温伯格平衡状态（P>0.05）。关联分析结果表明，g.36933082 G>A和g.36946470 G>A位点不同基因型在5个绵羊群体中的产羔数均无显著差异（P>0.05）；g.75378892 A>T位点在杂一代绵羊群体中TA基因型个体产羔数显著高于TT基因型（P<0.05）。生物信息学结果表明，3个位点均导致对应蛋白质的二级结构和三级结构发生变化。综上所述，B4GALNT2基因g.36933082 G>A和g.36946470 G>A位点不适用于5个绵羊群体多羔性状的选育，ESR1基因g.75378892 A>T位点可作为杂一代绵羊群体多羔性状的分子辅助标记。

Polymorphism of B4GALNT2 and ESR1 Genes and Its Association with Litter Size in Sheep

In order to explore the candidate loci affecting the lambing traits in the breeding of high-quality meat sheep in Ningxia, 5 sheep populations of Dorper sheep, Tan×Han hybrid sheep, hybrid generation 1, hybrid generation 2 and cross generation 1 were studied. Flight mass spectrometry technology was used to detect the polymorphism of beta-1, 4-N-acetyl-galactosaminyl transferase 2 (B4GALNT2) gene g. 36933082 G>A and g. 36946470 G>A and estrogen receptor 1 (ESR1) gene g. 75378892 A>T in 5 sheep populations and analyze their association with litter size in sheep. The secondary and tertiary structures of proteins before and after B4GALNT2 and ESR1 genes mutation were analyzed by bioinformatics online software. The results showed that there were three genotypes (AA, AG and GG) in g. 36933082 G>A and g. 36946470 G>A of B4GALNT2 gene, and GG genotype was the dominant genotype. There were three genotypes (AA, TA and TT) in g. 75378892 A>T of ESR1 gene, and AA genotype was the dominant genotype. g. 36933082 G>A and g. 36946470 G>A showed low polymorphism in 5 sheep populations (PIC<0.25), g. 75378892 A>T showed moderate polymorphism in 5 sheep populations (0.25<PIC<0.5), and the three loci were in Hardy-Weinberg equilibrium in 5 sheep populations. The correlation analysis of litter size results showed that g. 36933082 G>A and g. 36946470 G>A of different genotypes were not significantly different from those in 5 sheep populations (P>0.05), but g. 75378892 A>T in hybrid generation 1 sheep population, the litter size of individuals with TA genotype was significantly higher than that of TT genotype (P<0.05). Bioinformatics results showed that all three sites caused changes in the secondary and tertiary structures of the corresponding protein. In conclusion, g. 36933082 G>A and g. 36946470 G>A of B4GALNT2 gene were not suitable for the breeding of multiple lambing traits in 5 sheep populations, while g. 75378892 A>T of ESR1 gene could be considered as a molecular assistant marker for multiple lamb traits in hybrid generation 1 sheep population.