Faculty of Veterinary Science, University of Sydney, 425 Werombi Road, Camden NSW 2570, Australia.
Funct Integr Genomics. 2013 Mar;13(1):115-31. doi: 10.1007/s10142-012-0307-y. Epub 2013 Jan 17.
A combined analysis of a bovine and ovine mammary gland transcriptome from two similarly designed microarray experiments suggested a strong positive association between the differentially expressed genes (DEGs) implying that major pathways regulating the lactation process were evolutionarily conserved within the two species. Some distinct pathways identified indicate the physiological differences underlying the species. Novel techniques were established for the combined analysis of the transcriptomes of different species or heterogeneous platforms for comparative gene expression analysis allowing for greater experimental power to detect conserved pathways. Conserved DEGs were mainly related to lipid metabolism, amino acid synthesis, cell proliferation, signaling and immune systems indicating functional processes involved in the regulation of lactation including milk synthesis and lactation persistency. There were no functionally annotated DEGs that show antagonistic expression between sheep and cattle suggesting that the lactation process is essentially the same in the two species. DEGs that were found exclusively in sheep were mostly associated with gland morphogenesis while DEGs exclusively expressed in cattle, indicated that certain immune response and milk composition mechanisms were different in the bovine as compared to sheep. The conserved processes across the two species suggest the use of the ovine as a suitable model for lactation studies, considering the challenges and expense of conducting lactation physiology and genomics studies within the cow.
对来自两个设计相似的微阵列实验的牛和羊乳腺转录组进行联合分析表明，差异表达基因（DEGs）之间存在很强的正相关性，这表明调节泌乳过程的主要途径在这两个物种中是进化保守的。一些独特的途径表明了物种之间的生理差异。为不同物种或不同平台的转录组的联合分析建立了新的技术，用于比较基因表达分析，从而可以提高检测保守途径的实验能力。保守的 DEGs 主要与脂质代谢、氨基酸合成、细胞增殖、信号和免疫系统有关，表明参与泌乳调节的功能过程，包括牛奶合成和泌乳持续时间。没有功能注释的 DEGs 显示绵羊和牛之间的表达拮抗，这表明这两个物种的泌乳过程本质上是相同的。仅在绵羊中发现的 DEGs 主要与腺形态发生有关，而仅在牛中表达的 DEGs 则表明牛的某些免疫反应和牛奶成分机制与绵羊不同。这两个物种之间的保守过程表明，考虑到在奶牛中进行泌乳生理学和基因组学研究的挑战和费用，可以将绵羊用作泌乳研究的合适模型。
