El-Komy Shymaa M, Saleh Ayman A, Abdel-Hamid Tamer M, El-Magd Mohammed A
Department of Animal Production, Faculty of Agriculture, Tanta University, Tanta 31527, Egypt.
Department of Animal Wealth Development, Veterinary Genetics & Genetic Engineering, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44519, Egypt.
Animals (Basel). 2020 Jul 15;10(7):1203. doi: 10.3390/ani10071203.
For its role in the mediation of growth hormone (GH) galactopoietic effect, growth hormone receptor () was considered a functional candidate gene for milk performance in cattle. However, its genetic variation and potential effect have not been investigated in Egyptian buffaloes. This study aimed to screen for polymorphisms and study their associations with milk traits in Egyptian buffaloes. Polymerase chain reaction, single-strand conformation polymorphism, and sequencing were used to identify mutations in 4 exons (E4-E6 and E8) of the gene in 400 Egyptian buffaloes. No polymorphisms were found in E4, while 2 SNPs (c.380G>A/p.Arg127Lys and c.387C>T/p.Gly129) in E5, one silent mutation (c.435A>G/p.Pro145) in E6, and another missense mutation (c.836T>A/p.Phe279Tyr) in E8 were detected. The c.380G>A SNP in the extracellular domain was associated with milk yield, fat %, protein %, and 305-day milk, fat and protein yield, with higher levels in animals carrying the mutant A allele. The c.836T>A SNP in the transmembrane domain was associated with milk yield, fat %, protein %, and 305-day milk, fat and protein yield, with higher milk yield and lower fat %, protein %, fat and protein yield in the mutant A allele-animals. Interestingly, animals with the two mutant AA alleles produced higher milk yield, fat %, protein %, fat and protein yield, accompanied with upregulated expressions of GHR, GH, insulin-like growth factor 1 (IGF1), prolactin (PRL), prolactin receptor (PRLR), β-casein (encoded by CSN2 gene), and diacylglycerol acyltransferase-1 (DGAT1) genes and proteins in milk somatic cells. Therefore, selection of Egyptian buffaloes with mutant AA haplotypes for the novel c.380G>A SNP and the well-known c.836T>A SNP could improve milk yield and quality in buffaloes.
由于生长激素受体（GHR）在介导生长激素（GH）的促乳作用中发挥作用，因此它被认为是牛产奶性能的一个功能性候选基因。然而，其基因变异及其潜在影响在埃及水牛中尚未得到研究。本研究旨在筛选GHR基因的多态性，并研究它们与埃及水牛产奶性状的关联。采用聚合酶链反应、单链构象多态性分析和测序技术，对400头埃及水牛GHR基因的4个外显子（E4-E6和E8）进行突变鉴定。在E4中未发现多态性，而在E5中检测到2个单核苷酸多态性（c.380G>A/p.Arg127Lys和c.387C>T/p.Gly129），在E6中检测到1个沉默突变（c.435A>G/p.Pro145），在E8中检测到另一个错义突变（c.836T>A/p.Phe279Tyr）。细胞外结构域中的c.380G>A单核苷酸多态性与产奶量、乳脂率、乳蛋白率以及305天产奶量、乳脂产量和乳蛋白产量相关，携带突变A等位基因的动物中这些指标水平更高。跨膜结构域中的c.836T>A单核苷酸多态性与产奶量、乳脂率、乳蛋白率以及305天产奶量、乳脂产量和乳蛋白产量相关，突变A等位基因的动物产奶量更高，而乳脂率、乳蛋白率、乳脂产量和乳蛋白产量更低。有趣的是，具有两个突变AA等位基因的动物产奶量、乳脂率、乳蛋白率、乳脂产量和乳蛋白产量更高，同时乳腺体细胞中GHR、GH、胰岛素样生长因子1（IGF1）、催乳素（PRL）、催乳素受体（PRLR）、β-酪蛋白（由CSN2基因编码）和二酰甘油酰基转移酶-1（DGAT1）基因及蛋白的表达上调。因此，选择具有新型c.380G>A单核苷酸多态性和著名的c.836T>A单核苷酸多态性的突变AA单倍型埃及水牛，可提高水牛的产奶量和奶品质。
