【作者】 王丽娟；

【导师】 王志玉；

【作者基本信息】 山东大学 ， 流行病与卫生统计学， 2008， 硕士

【摘要】 研究背景催乳素是垂体前叶分泌的多肽类激素,具有多种生物学功能。基因阻断实验证明它在腺体形成、泌乳及乳蛋白基因的表达方面发挥重要的作用。生长激素受体是催乳素和生长激素受体超家族的成员,它通过与生长激素结合,在动物的生长和发育等生长代谢过程发挥作用。因此催乳素和生长激素受体基因可能是与影响奶牛产奶性状的数量性状位点关系最为密切的候选基因。催乳素与生长激素受体基因编码区与调控区等位基因的变异有可能对奶牛产奶性状有直接或间接的效应。目的本研究的目的在于证实催乳素基因与生长激素受体基因的多态性与中国荷斯坦奶牛的产奶性状是否有关联性。方法本研究的研究对象为300头中国荷斯坦奶牛的DNA样品。通过PCR-RFLP方法或CRS-RFLP方法对所有样本进行基因分型。使用Primer Premier5.0和Oligo 5.0软件进行引物设计。基因变异与产奶性状之间的关联性应用SAS 9.0统计软件,利用最小二乘法拟合线性模型进行分析。结果在催乳素基因8398位点,300头荷斯坦奶牛中A、G等位基因的频率分别为0.257和0.743,基因型AA、AG和GG的频率分别为0.010、0.497和0.493,在第Ⅱ泌乳期,GG基因型群体的乳蛋白率高于AG型群体(P＜0.05),AG基因型群体的产奶量高于GG型群体(P＜0.01)。在8377位点,275头荷斯坦奶牛中C、G等位基因的频率分别为0.815和0.185,基因型CC、GC和GG的频率分别为0.655、0.320和0.025,GG基因型群体体产奶量显著高于CC及GC基因型(P＜0.05),GC基因型群体乳蛋白率显著高于CC型(P＜0.05)。在8510位点,280头荷斯坦奶牛中C、T等位基因的频率分别为0.204和0.796,基因型CC、TC和TT的频率分别为0.204、0.000和0.796,CC基因型群体产奶量显著高于TT基因型(P＜0.05)。在生长激素受体基因4962位点,290头荷斯坦奶牛中A、T等位基因的频率分别为0.628和0.272,基因型AA、TA和TT的频率分别为0.469、0.317和0.214,TT基因型群体乳脂率显著高于AA基因型(P＜0.05)。结论在催乳素基因8398位点,G为可提高乳蛋白率的有利等位基因,而A等位基因可提高乳产量。在8377位点,G为可提高乳蛋白率和乳产量的有利等位基因。在8510位点,C为可提高乳产量的有利等位基因。在生长激素受体基因4962位点,T为可提高乳脂率的有利等位基因。综上所述,本研究建立了快速有效的催乳素及生长激素受体基因位点多态性的分子检测方法,并在中国荷斯坦牛群体中验证了这些突变位点的不同基因型对产奶性状具有显著效应。因此这些位点可以作为一个候选的分子遗传标记,应用到我国荷斯坦牛分子育种中,通过对产奶性状进行标记辅助选择,提高选择准确性和效率,以期快速高效地改善牛群的生产性能。更多还原

【Abstract】 Background Prolactin is a polypeptide hormone with multiple functions,secreted mainly by the anterior pituitary gland. Gene disruption experiments proved their mandatory role for mammary gland development, lactogenesis, and expression of milk protein genes. The growth hormone receptor (GHR) is a member of the prolactin and growth hormone receptor super family. GHR through binding to GH plays an important role in animal metabolic process like growth and development .Therefore the bovine prolactin gene (PRL) and GHR gene seem to be excellent candidates for linkage analysis with quantitative trait loci (QTS) affecting milk production traits. Allelic variation in the structural or regulatory sequences of the PRL gene and GHR gene would be of interest because of the possible direct or indirect effect on milk production. SNPs occurring within the prolactin gene may influence the chemical composition of milk.Objectives To evaluate whether PRL and GHR gene polymorphisms might be associated with the milk production traits in Chinese Holstein cows.Methods The study included 300 DNA sanmples of Chinese Holstein cows. All genotyping were identified by the methods of PCR-RFLP and CRS-RFLP. Software Primer Premier 5.0 and Oligo 5.0 were used to design all the primers.The associations between variants of the genes and milk performance traits were analyzed by the GLM procedure (SAS 9.0).Results About PRL 8398 site, the frequency of allele A and G is 0.257 and 0.743 respectively. The frequency of genotype AA、AG and GG is 0.010, 0.497 and 0.493 respectively. In lactationⅡ,The least squares of protein percentage of this population was higher for genotype GG than for genotype AG (P<0.05) . The least squares of milk yield of this population was higher for genotype AG than for genotype GG (P<0.01). About PRL 8377 site, the frequency of allele C and G is 0.815 and 0.185 respectively. The frequency of genotype CC、GC and GG is 0.655, 0.320 and 0.025 respectively. The least squares of milk yield of this population was higher for genotype GG than for genotype CC and GC(P<0.05). The least squares of protein percentage of this population was higher for genotype GC than for genotype CC (P<0.05). About PRL 8510 site, the frequency of allele C and T is 0.204 and 0.796 respectively. The frequency of genotype CC、TC and TT is 0.204, 0.000 and 0.796 respectively. The least squares of milk yield of this population was higher for genotype CC than for genotype TT (P<0.05). About GHR 4962 site, the frequency of allele C and G is 0.628 and 0.272 respectively. The frequency of genotype AA、TA and TT is 0.469, 0.317 and 0.214 respectively. The least squares of fat percentage of this population was higher for genotype TT than for genotype AA (P<0.05).Conclusion About PRL 8398 site, allele G is a positive allele to inhance protein percentage, while allele A is a positive allele to inhance milk yield. About PRL 8377 site, allele G is a positive allele to inhance protein percentage and milk yield. About PRL 8510 site, allele C is a positive allele to inhance milk yield. About GHR 4962 site, allele T is a positive allele to inhance fat percentage. In conclusion, we established a quick and effective method to identify the 8398, 8377, 8510 locus of PRL and 4962 locus of GHR in Chinese Holstein cows. We further confirmed that these sites were significantly associated with dairy production traits. So we could take these genes as candidate molecular markers and apply them to dairy cattle breeding using maker assisted selection(MAS), which could increase the accuracy and efficiency of selection an improve the production of Chinese Holstein rapidly and effiectively.更多还原