Correlation analysis of milk-derived key unsaturated fatty acid synthesis genes and fatty acid composition in fresh milk of goats(山羊乳源不饱和脂肪酸合成关键基因与鲜奶脂肪酸组成的关联分析)

Beneficial fatty acids, especially unsaturated fatty acids, are critical nutritional components of ruminant fresh milk, exerting multiple physiological effects. However, the regulatory mechanisms underlying unsaturated fatty acid synthesis in the mammary gland remain unwell understood. Here, this study investigated the correlation between functional gene expression in mammary epithelial cells and milk fat metabolism in mid-lactation dairy goats. Through milk fat composition analysis combined with real time fluorescent quantitative polymerase chain reaction (PCR), we detected the fatty acid contents and relative expression levels of seven core factors in milk-derived RNA, such as liver X receptor (LXR), elongation of very long chain fatty acids like 5 (ELOVL5), and stearoyl-CoA desaturase 1 (SCD1). The results showed that liver X receptor β gene (LXRB) exhibited significant co-expression patterns with ELOVL5 and SCD1. All three factors (LXRB, ELOVL5, and SCD1) were strongly positively correlated with C22:6 content and daily production (P＜0.01). No significant correlations were observed between liver X receptor α gene (LXRA) expression and ELOVL5/SCD1 expression. Additionally, other genes showed irregular correlations with unsaturated fatty acid content and daily production in milk. This research provides evidence for the targeted regulation of milk-derived LXRB on fatty acid elongases and desaturases, offering theoretical data to further clarify the molecular regulatory network underlying beneficial fatty acid synthesis in fresh milk.(有益脂肪酸成分尤其是不饱和脂肪酸，是反刍动物鲜奶营养价值的重要组成部分，具有多重生理效应，但乳腺内不饱和脂肪酸合成调节机制尚不十分清晰。为此，本研究以泌乳中期奶山羊为研究对象，系统开展乳腺上皮细胞功能基因表达与乳脂代谢的关联性研究。通过乳脂成分分析结合实时荧光定量聚合酶链反应技术，对乳中脂肪酸含量和乳源RNA中肝X受体（liver X receptor, LXR）、极长链脂肪酸延伸酶5（elongation of very long chain fatty acids like 5, ELOVL5）、硬脂酸辅酶A去饱和酶1（stearoyl-CoA desaturase 1, SCD1）等7个核心调控因子进行检测。结果表明，肝X受体β基因（liver X receptor β gene, LXRB）与ELOVL5、SCD1存在显著协同表达特征，且三者均与C22：6的含量和日产量呈极显著正相关（P＜0.01）。肝X受体α基因（liver X receptor α gene, LXRA）与ELOVL5、SCD1表达量无显著相关性，而其他基因表达量与乳中不饱和脂肪酸的含量和日产量之间存在不规律性的相关性。本研究为明确乳源LXRB与脂肪酸延伸酶和去饱和酶的靶向调控机制提供了证据，为进一步解析鲜奶中有益脂肪酸合成的分子调控网络提供了理论数据。)