The epigenetic mechanisms of adaption to the hot and humid climate in Hu sheep (Ovis aries).

Hu sheep is characterized by its excellent fecundity and high adaptability to various ecological environments. To reveal the molecular basis involved in Hu sheep, we first examined the 10 index of neuroendocrine and metabolism in blood in Hu sheep during non-stress period (April-May) and stress period (July-August) using ELISA, including CRH, adrenocorticotropic hormone (ACTH), cortisol, aldosterone, adrenaline, T3,T4, SOD, GSH-PX, and T-AOC. Then we conducted the Whole genome DNA methylation sequencing in blood and performed the comparative analysis of global DNA methylation between the non-stress period and the stress period. Our results demonstrated that among the 10 index tested in blood, only ACTH, T3, and T-AOC were significantly changed (p < 0.01) in Hu sheep between two periods. This indicates Hu sheep's special adaptability to the high hygrothermal environment takes the decrease of metabolic level and total antioxidant capacity as compensation, which differ obviously from other intolerant hygrothermal animals. At the epigenetic level, differential methylation of TPO, ADCY9, PRKACB, and CREB5 play important roles in excellent resistance to hygrothermel environment in Hu sheep by modulation of the secretion of in neuroendocrine hormones (T3, ACTH) and thermogenesis. These findings are valuable for breeding the novel animal breeds resistant to climate stress.