Department of Animal Science, College of Animal Science, Xinjiang Agricultural University, Urumqi, 830052, China.
Institute of Biothermal Science and Technology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China; State Key Laboratory of Sheep Genetic Improvement and Healthy Breeding, Institute of Animal Husbandry and Veterinary Sciences, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihhotze, 832000, China; National Engineering Laboratory for Animal Breeding, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
Theriogenology. 2022 Feb;179:78-86. doi: 10.1016/j.theriogenology.2021.11.008. Epub 2021 Nov 16.
Heat stress not only affects the physical condition but also affects reproductive performance in sheep. A thorough understanding of the molecular and physiological mechanisms underlying heat stress would certainly improve livestock productivity and provide genetic evaluation ways for heat resistant breeds selection. In this study, 85 Turpan Black sheep, a breed exhibited excellent heat resistance from long-term artificial selection, and 85 heat sensitive Kazakh sheep in Turpan basin were tested for physiological and reproductive performance from July to August in summer. The results showed that the estrus rate was significantly higher in Turpan Black sheep (P < 0.05), while the heart rate and respiratory rate of Turpan Black sheep are significantly lower than that of Kazakh sheep (P < 0.05). Furthermore, to clarify genes participated in heat stress response, the pituitary, ovarian and hepatic tissues from three Turpan Black sheep and three Kazakh sheep were subjected to RNA-seq. The results indicated that 32, 49 and 69 genes were up-regulated, and 39, 60 and 145 genes were down-regulated in pituitary, ovarian and hepatic tissues in Turpan Black sheep compared with that of the Kazakh sheep, respectively. KEGG and gene set enrichment analysis showed that the differentially expressed genes were mainly involved in signal transduction pathways. In particular, the differentially expressed genes in hepar were enriched in the energy metabolism pathway, while the differentially expressed genes in ovarian tissue were enriched in the ovarium steroidogenesis pathway. In conclusion, our results implied that the pituitary-ovary axis might include hepar as downstream targeted organism in heat resistant regulation. Under heat stress, the signals released from pituitary would impact steroidogenesis in ovary, and further alter energy metabolism in hepar. As we know, this is the first comparative study to investigate the gene expression in multi-tissue in sheep under heat stress.
热应激不仅影响绵羊的身体状况，还影响其繁殖性能。深入了解热应激的分子和生理机制，必将提高畜牧业的生产力，并为耐热品种的选择提供遗传评估方法。本研究以长期人工选择表现出优异耐热性的吐鲁番黑羊 85 只和吐鲁番盆地热敏感哈萨克羊 85 只为研究对象，于 7-8 月夏季对其生理和繁殖性能进行了测试。结果表明，吐鲁番黑羊的发情率显著高于哈萨克羊（P<0.05），而吐鲁番黑羊的心率和呼吸率明显低于哈萨克羊（P<0.05）。此外，为了阐明参与热应激反应的基因，我们对 3 只吐鲁番黑羊和 3 只哈萨克羊的垂体、卵巢和肝脏组织进行了 RNA-seq 分析。结果表明，与哈萨克羊相比，吐鲁番黑羊的垂体、卵巢和肝脏组织中分别有 32、49 和 69 个基因上调，39、60 和 145 个基因下调。KEGG 和基因集富集分析表明，差异表达基因主要参与信号转导途径。特别是，在肝脏组织中，差异表达基因富集在能量代谢途径中，而在卵巢组织中，差异表达基因富集在卵巢甾体生成途径中。总之，我们的研究结果表明，垂体-卵巢轴可能包括肝脏作为耐热调节的下游靶器官。在热应激下，垂体释放的信号会影响卵巢的甾体生成，并进一步改变肝脏的能量代谢。据我们所知，这是首次在绵羊中进行多组织比较研究。
