中文摘要：

为了解牦牛乳腺中乳脂代谢和转运的分子机理。本实验以AC馏、，他曰钳P和MRPL39作为内参基因．通过荧光定量检测技术，对牦牛哺乳期（-15、1、15、30、60、120d和240d）内与牦牛乳脂合成（AGPAT6、DGATl和DGAT2）、乳脂转运（FABP3、ABCG2和ABCAl）和转录调控（PPARGClA）相关的7个基因的表达进行检测．结果表明：ABCAl、DGATl和PPARGClA在1d达到峰值，随后逐渐下降，在240d恢复到较低的表达水平：ABCG2和DGAT2的表达水平分别在30d和60d达到峰值，随后逐渐下降；AGPAT6和FABP3的表达在30d达到峰值．随后缓慢下降，在240d恢复低表达水平；通过统计分析发现，这7个基因在哺乳期内不同时间点的表达呈现极显著性差异（P〈0．01），并且其中的6个基因（除ABCAl外）在牦牛乳腺中的表达峰值出现时间与荷斯坦奶牛相比均有所提前，同时也早于牦牛自身产奶量峰值出现时间；皮尔森相关性分析发现，7个目的基因的平均表达量与产奶量呈弱正相关（r=0．278，P=0．651），而与总RNA浓度呈强正相关（r=0．849，P=0．016）。其中ABCAl和DGATI与总RNA浓度和产奶量均呈负相关，ABCG2、AGPAT6、DGAT2、FABP3、PPARGClA与产奶量均呈正相关。本研究结果表明，牦牛的乳脂代谢和转运基因在哺乳期的表达谱与荷斯坦奶牛不同，具有牦牛自身特异性。

英文摘要：

To understand the molecular mechanism of milk fat synthesis and transporting genes of Yak. The expression level of fatty acid synthesis （AGPAT6,DGAT1 and DGAT2）, fatty acid trafficking（FABP3,ABCG2 and ABCAI） and transcription regulation gene （PPARGC1A） during lactation cycle （-15 d, 1 d, 15d, 30 d, 60 d, 120 d, and 240 d） were detected by qPCR method with ACTB, ITGB4BP and MRPL39 as reference genes. The results showed that the expression peaks of ABCA1, DGAT1 and PPARGC1A genes appeared at 1 d post parturation. Then, they greatly decreased at 240 d. The highest expressions level of ABCG2 and DGA T2 were observed at 30 d and 60 d. Then, they were declined until 240 d. The expression peak of A GPA T6 and FABP3 appeared at 30 d. From 30 d to 240 d, they went down slowly and lower expression level can also be observed at 240d. Statistical analysis results indicated that the mRNA level of all 7 genes had a significant time effect （P〈0.01）. The results suggested that the expression peaks of these genes （except for ABCAI） in mammary gland of yak were earlier than the expression peaks in mammary gland of Holstein dairy cow, and also earlier than the peak of milk yield of yak. Pearson correlations analysis results demonstrated that the average expression level of all 7 genes was significant positive correlated with total RNA concentration （r=0.849, P=0.O16）and were positive correlated with yak milk yield （r=0.278, P=0.651）. Among them, ABCA1 and DGAT1 were negative correlation with RNA concentration and yak milk yield. On the contrary, ABCG2, AGPAT6, DGAT2, FABP3 and PPARGC1A genes were positive correlation with yak milk yield. It indicated that the expression pattern of milk fat synthesis and transportation in yak mammary gland was different from Holstein dairy cow and has its own expression specificity.