Dissection of the regulatory function of HIF1α in hypoxic stress and identification of the favored haplotype for breeding applications in crayfish (Procambarus clarkii).

The red swamp crayfish (Procambarus clarkii) is an economically important freshwater crustacean in China. However, the harvest of farmed crayfish is often reduced because of high mortality caused by hypoxic stress. In this study, three single nucleotide polymorphisms in the hypoxia-inducible factor-1α gene (HIF1α) were identified in the investigated crayfish germplasm populations, and these variants were associated with the hypoxia tolerance of crayfish. Further association analysis based on three different crayfish populations identified the most favorable HIF1α haplotype (CC-CC-CC) for hypoxia tolerance. Furthermore, to verify the function of HIF1α, RNA interference, transcriptomic analysis, and biochemical assays were employed to investigate the mechanisms underlying the role of this gene in the hypoxic adaptation process of crayfish. The results showed that the inhibition of HIF1α significantly impaired hypoxic adaptation at the metabolic and physiological levels in crayfish, as evidenced by blocked anaerobic respiration, disrupted energy metabolism, and compensatory increase in antioxidant capacity. Collectively, these results provide new insights into the molecular mechanisms underlying hypoxic adaptation in crayfish and lay a theoretical foundation for the cultivation of hypoxia-tolerant crayfish varieties.