Brym Paweł, Kamiński Stanislaw, Ruść Anna
Department of Animal Genetics, University of Warmia and Mazury, M. Oczapowskiego 5, 10-957 Olsztyn, Poland.
J Appl Genet. 2004;45(4):445-52.
Milk protein genes expression in cows' mammary epithelial cells is regulated mostly by the action of prolactin mediated through the STAT5A transcription factor. The STAT5A gene is a potential quantitative trait locus (QTL) and genetic marker of production traits in dairy cattle. The sequence of the bovine STAT5A gene was analysed in this study to investigate if mutations in this sequence might be responsible for quantitative variations in milk yield and composition. Ten PCR fragments representing most important functional domains of STAT5A were screened for polymorphism. Using the SSCP method a new SNP (A/G) was found, located in intron 9 at position 9501 (GenBank AJ237937). The frequencies of alleles were estimated in 186 Black-and-White cows (0.52 and 0.48 for A and G, respectively) and in 138 Jersey cows (0.58 and 0.42 for A and G, respectively). For Black-and-White cows with different STAT5A genotypes no significant associations between STAT5A genotypes and milk performance traits were found. Statistically significant differences in the first and second lactations for milk yield, fat and protein content were found in Jersey cows. Cows with the GG genotype showed the highest milk yield, while cows with genotypes AA and AG showed higher protein contents when compared to cows with the GG genotype. Interestingly, cows with genotype AG showed significantly higher protein yields in comparison to cows with the AA genotype. For fat content, cows with genotype AA showed the highest level of this trait in the 1st and 2nd lactation. Further studies are necessary to evaluate an allele substitution effect in the population of sib-families of STAT5A heterozygous bulls.
奶牛乳腺上皮细胞中乳蛋白基因的表达主要受催乳素通过信号转导及转录激活因子5A（STAT5A）转录因子介导的作用调控。STAT5A基因是奶牛生产性状的潜在数量性状位点（QTL）和遗传标记。本研究分析了牛STAT5A基因的序列，以调查该序列中的突变是否可能导致产奶量和乳成分的数量变异。筛选了代表STAT5A最重要功能域的10个PCR片段的多态性。使用单链构象多态性（SSCP）方法发现了一个新的单核苷酸多态性（A/G），位于第9内含子的9501位（GenBank AJ237937）。在186头黑白花奶牛（A和G等位基因频率分别为0.52和0.48）和138头泽西奶牛（A和G等位基因频率分别为0.58和0.42）中估计了等位基因频率。对于具有不同STAT5A基因型的黑白花奶牛，未发现STAT5A基因型与产奶性能性状之间存在显著关联。在泽西奶牛的第一和第二泌乳期，产奶量、脂肪和蛋白质含量存在统计学显著差异。GG基因型的奶牛产奶量最高，而与GG基因型的奶牛相比，AA和AG基因型的奶牛蛋白质含量更高。有趣的是，与AA基因型的奶牛相比，AG基因型的奶牛蛋白质产量显著更高。对于脂肪含量，AA基因型的奶牛在第一和第二泌乳期该性状水平最高。有必要进一步研究评估STAT5A杂合公牛同胞家系群体中等位基因替代效应。
