Physiological changes and transcriptional modulation of HIF-αs in Siberian sturgeon in response to hypoxia

Abstract

To clarify the effects of acute hypoxia on physiological response and mRNA expression of Hypoxia-inducible factors (HIFs) in Siberian sturgeon, a chondrostean fish, severe hypoxia treatment was implemented by transfer of sturgeons from normoxia (DO =7 mg/mL) to hypoxia (DO = 2 mg/mL). We found that the levels of serum cortisol, GLU, SOD, LDH, CK and CREA increased significantly at the early time-points post hypoxia exposure. Whereas the activity of immune related enzyme — AKP showed a sudden drop, followed by a recovery. Further, we identified and characterized three hif-αs cDNA sequences, namely Abhif-1α, Abhif-2α, and Abhif-3α. The mRNA abundance of three hif-αs was all rich in brain, heart and liver. During acute hypoxia exposure, Abhif-1α and Abhif-3α mRNA expression levels increased significantly in the heart, gill and brain at early time-points, and gradually declined later on. Abhif-2α only showed a slight increase in the gill upon hypoxia stress. In conclusion, we observed that, acute hypoxia affected the muscle function and immune related enzyme activity of Acipenser baeri; in response to hypoxia stress, sturgeons enhanced antioxidant capacity, anaerobic metabolism and up regulated the transcriptional expression of Abhif-1α and Abhif-3α. Our results might be helpful for further understanding of the potential effect of hypoxia on chondrostean fish and their molecular anti-hypoxia mechanisms.