为揭示奶牛肝脏脂肪变性影响生产性能的代谢机制,以健康奶牛为对照,本研究比较分析了肝脏轻度脂肪变性奶牛的生理生化指标和转录组测序结果.肝脏组织学观察发现,当脂肪变性时,苏木精-伊红染色的肝脏组织切片中可观察到大小不等的近圆形空泡.与健康奶牛相比,肝脏轻度脂肪变性奶牛的脂肪矫正乳、能量矫正乳、乳脂含量均显著降低,而血浆生化指标无明显差异.对肝脏组织进行转录组测序,共发现241个差异表达基因(differentially expressed genes,DEGs),其中表达下调的DEGs有136个,表达上调的DEGs有105个.通过基因本体(gene ontology,GO)功能注释发现,DEGs主要富集于脂质代谢相关的生物学过程与分子功能中;通过京都基因和基因组数据库(Kyoto Encyclopedia of Genes and Genomes,KEGG)通路富集分析发现,DEGs显著富集于类固醇生物合成、胆固醇代谢、非酒精性脂肪性肝病等脂质代谢相关通路.另外,对全体基因进行基因集富集分析(gene set enrichment analysis,GSEA)发现,基因主要富集于脂肪酸延长通路、过氧化物酶体增殖物激活受体信号通路等影响脂质代谢的重要通路.上述结果表明,肝脏脂肪变性影响了奶牛肝脏的脂质代谢,进而影响了奶牛全身代谢,引起了奶牛乳脂含量等生产性能改变.
Metabolic mechanism of hepatic steatosis affecting production performance of dairy cows during peak lactation
In order to explore the metabolic mechanism of hepatic steatosis affecting production performance of dairy cows,the physiological and biochemical indexes and transcriptome sequencing results of dairy cows with mild hepatic steatosis were compared and analyzed,with healthy dairy cows used as controls.Histological examination of liver tissue revealed that when steatosis occurred,hematoxylin-eosin stained sections of liver tissue showed nearly round vacuoles of varying sizes.Compared with those of healthy dairy cows,the yields of fat-corrected milk,energy-corrected milk and the milk fat content of dairy cows with mild hepatic steatosis were significantly lower(p＜0.01),and there were no significant differences in plasma biochemical indexes.A total of 241 differentially expressed genes(DEGs)were found in liver by transcriptome sequencing,including 136 down-regulated DEGs and 105 up-regulated DEGs.Gene ontology(GO)functional annotation showed that DEGs were enriched mainly in biological processes and molecular functions related to lipid metabolism.The Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analysis showed that DEGs were enriched in steroid biosynthesis,cholesterol metabolism,non-alcoholic fatty liver disease and other lipid metabolism-related pathways.In addition,gene set enrichment analysis(GSEA)showed that genes were enriched in important pathways affecting lipid metabolism,such as fatty acid elongation and peroxisome proliferator-activated receptor signaling pathway.The results suggested that mild hepatic steatosis affected the lipid metabolic process of dairy cows,and then affected the metabolism of whole body of dairy cows,resulting in differences in production performance of dairy cows such as milk fat content.
万方数据
