中国荷斯坦牛Toll样受体4基因的遗传多态性与体细胞评分的关联分析

试验旨在研究中国荷斯坦牛Toll样受体4(toll-like receptor 4,TLR4)基因的遗传多态性及其与体细胞评分(somatic cell score,SCS)的关联性,寻找与乳房炎相关的分子标记,加快中国荷斯坦牛的抗病育种。利用PCR-RFLP和PCR-SSCP技术对30个公牛家系的610头中国荷斯坦牛TLR4基因进行多态性检测,用最小二乘均数法对TLR4基因的多态位点与SCS进行相关分析。结果发现,试验共检测到2个单核苷酸多态(single nucleotide polymorphisms,SNPs),TLR4基因5'侧翼区存在SNP -226 G>C突变,经PCR-RFLP检测发现3种基因型:GG、GC和CC,基因型频率分别为0.208、0.482和0.310;外显子3存在SNP 1760 C>T突变,经PCR-SSCP检测发现3种基因型:CC、TC和TT,基因型频率分别为0.738、0.225和0.007,以上2位点均偏离Hardy-Weinberg 平衡。对于SNP -226 G>C位点,基因型个体的SCS差异不显著;对于SNP 1760 C>T位点,CC基因型个体的SCS最小二乘均值极显著低于TT和TC基因型个体(P<0.01)。SNP 1760 C>T的CC基因型对于中国荷斯坦牛的SCS有较大的遗传效应,可作为分子标记应用于奶牛乳房炎抗性筛选。

Genetic Polymorphism of TLR4 Gene and its Associations with Somatic Cell Score in Chinese Holstein Cattle

The polymorphism of toll-like receptor 4(TLR4) gene and its correlation with somatic cell score (SCS) in Chinese Holstein cattle were analyzed for the purpose of providing molecular markers in the marker-assisted selections (MAS) to accelerate the disease-resistant breeding progress in Chinese Holstein cattle. The polymorphism of TLR4 gene was detected by PCR-RFLP and PCR-SSCP technique in 610 Chinese Holstein cattle cattle from 30 bull families. The associations between polymorphic sites of TLR4 gene and SCS were analyzed by the least square mean analysis. Two SNPs were found, SNP -226 G>C was found in the 5' flanking region of TLR4 gene, three genotypes (GG, GC and CC) were found in 610 Chinese Holstein cattle by PCR-RFLP, and the frequencies of GG, GC and CC genotypes were 0.208, 0.482 and 0.310, respectively. SNP 1760 C>T was found in the exon 3 of TLR4 gene, three genotypes (GG, GC and CC) were found in 610 Chinese Holstein cattle by PCR-SSCP, and the frequencies of CC, TC and TT genotypes was 0.738, 0.225 and 0.007, respectively. Chi-square tested showed Chinese Holstein cattle was not in Hardy-Weinberg equilibrium at the two sites. There were no significant differences in SCS among genotypes for SNP -226 G>C, least square mean of SCS for CC genotype was very significantly lower than that for TT and TC genotypes(P<0.01). CC genotype for SNP 1760 C>T site had a great genetic effect on SCS in Chinese Holstein cattle, which could be used as a candidate marker for mastitis resistance selection in dairy cattle.