Yaks (Bos grunniens) live primarily in the Qinghai-Tibetan plateau (altitude: 2000–5000 m). Their milk presents unusual characteristics, containing large amounts of solids including fat and protein, and it is, therefore, important to understand the genetic makeup of the yak. To identify potentially critical genes playing a role in yak mammary tissue from colostrum to mature milk phase of lactogenesis, the early lactation (colostrum) stage (ELS; day 1 after parturition) and mature lactation (milk) stage (MLS; day 15) were chosen for comparison. An ELS-specific cDNA library was established by suppression subtractive hybridization and 25 expressed sequence tags at ELS were identified by sequencing and alignment. To further confirm our results the expression levels of 21 genes during the lactation cycle were measured using quantitative real-time RT-PCR (qRT-PCR). The qRT-PCR results confirmed 9 significantly up-regulated genes at ELS vs. MLS in yak mammary tissue, in which thel-amino acid oxidase 1 (LAO1) and collagen, type I, alpha I (COL1A1) were the most significantly up-regulated. During the lactation cycle, the highest expression of some milk fat genes (i.e.,XDHandFABP3) in yak mammary tissue appears earlier than that in dairy cow. Our data also indicateMYCpotentially playing a central role through putative regulation ofCOL1A1,CD44,SPARC,FASNandGPAM.

中文翻译：

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牦牛哺乳期乳腺组织差异表达基因的鉴定与验证

牦牛（野牛）主要生活在青藏高原（海拔：2000-5000米）。他们的牛奶呈现出不寻常的特征，含有大量的固体，包括脂肪和蛋白质，因此了解牦牛的基因组成很重要。为了确定在牦牛乳腺组织中发挥作用的潜在关键基因，从初乳到泌乳期的成熟乳期，早期泌乳（初乳）阶段（ELS；分娩后第 1 天）和成熟泌乳（乳）阶段（MLS；第 15 天）是选择进行比较。通过抑制消减杂交建立了ELS特异性cDNA文库，并通过测序和比对鉴定了ELS处表达的25个序列标签。为了进一步证实我们的结果，使用定量实时 RT-PCR (qRT-PCR) 测量了泌乳周期期间 21 个基因的表达水平。l-氨基酸氧化酶 1 (LAO1) 和胶原蛋白，I 型，α I (COL1A1) 是最显着的上调。在泌乳周期中，一些乳脂基因（即，XDH和FABP3) 在牦牛乳腺组织中的出现早于奶牛。我们的数据还表明我的C通过推定的监管可能发挥核心作用COL1A1,CD44,SPARC,FASN和GPAM.