天祝白牦牛OXGR1基因多态性与体尺性状的关联性分析

为了研究牦牛α-酮戊二酸（盐）受体1（Oxoglutarate receptor1, OXGR1）基因多态性与其体尺性状的相关性，本文以4-8岁天祝雄性（阉）白牦牛的血液DNA（n=192）为实验材料并构建DNA混合池。通过DNA直接测序法检测OXGR1的核苷酸序列潜在的多态位点；利用高分辨率熔解曲线分析技术 (High Resolution Melting，HRM ) 进行分型。采用SHESIS软件对OXGR1基因多态位点进行连锁不平衡分析；运用 PIC-Calc 0.6软件分析多态信息含量；采用卡方检验检测 Hardy- Weinberg平衡；运用SPSS20.0软件对多态位点与体尺性状进行关联分析；运用RNAFOLD、ExPASy和Swiss-model软件对OXGR1基因突变前后的蛋白结构进行预测分析。结果表明：天祝白牦牛OXGR1基因发现有两个多态位点，分别为347(A/G)和678(G/A)，每个位点均有3种基因型（AA、AG、和GG），其优势基因型分别为GG和AA。两个SNPs均达到Hardy-Weinberg 平衡（P＞0.05），存在强连锁不平衡（D’＞0.75, R²＞0.33），且均表现为中度多态（0.25< PIC< 0.5）。上述位点不同基因型在体斜长、体高、胸围和管围存在显著差异（P＜0.05）。分子结构预测显示：347 位点处突变为错义突变，其编码的氨基酸由天冬酰胺变为丝氨酸。突变后OXGR1 mRNA二级结构、蛋白质二级结构及三级结构均发生改变。上述结果表明: OXGR1基因可作为牦牛分子育种的候选分子标记，为今后牦牛遗传资源的保护、开发以及新品种的选育提供依据。

Association of polymorphisms of the OXGR1 with body measurement traits in Tianzhu white yak (Bos grunniens)

The aim of this study was to examine the correlation between polymorphism of the Oxoglutarate receptor1 (OXGR1) and body measurement traits in yak (Bos grunniens). A total of 192 blood genomic DNA samples (age 4-8 years, male/castration) were randomly selected to construct the DNA pool. Direct DNA sequencing was used to detect potential polymorphic sites of the OXGR1. The results showed two SNPs (347(A/G) and 678 (G/A)) in Tianzhu White yak OXGR1， each with three kinds of genotype (AA, AG and GG) in high resolution melting curves (HRM), and the superior genotypes were GG and AA, respectively. The result of a χ²- test suggested that two SNPs met Hardy-Weinberg balance (P＞0.05) and have strong linkage disequilibrium between two loci (D’ > 0.75, R2 > 0.33) by SHESIS software. There was a moderate diversity located in two SNPs (0.25 < PIC < 0.5). The different genotypes of the two SNPs had significant differences in body length, body height, chest girth and tube girth (P＜0.05). The results of bioinformatics analysis revealed that the mutation of the 347 locus was a missense mutation, and the coded amino acid was translated from Asn to Ser, also the mRNA secondary structure, and secondary and tertiary structures of the protein were changed. Above all, the OXGR1 can be used in marker-assisted selection of yak, which could provide the basis for protection and development of yak genetic resources and breeding of new varieties in the future.