Key genes and pathways associated with molecular regulation under acute hypoxic stress in Megalobrama amblycephala

Megalobrama amblycephala is economically important for pisciculture in China. However, its intolerance to low oxygen makes it highly susceptible to hypoxia and death during the aquaculture process. In this study, a model of hypoxic stress was constructed in the Pujiang No. 2 strain of M. amblycephala. The key genes related to the hypoxia adaptation were screened via multi-omics coanalysis, thereby revealing the molecular regulatory mechanism of M. amblycephala under acute hypoxia conditions. Based on the LOE dissolved oxygen threshold, two groups of low oxygen sensitivity and tolerance were selected—namely, the sensitive group (HS) and tolerant group (HT), with the normoxic group (C0) as the control. The results indicated that the key genes nos2, hif1, epo, vegfa, hif1an, trib3, eno3, ldlr, fscn1, hmox1, and gapdh were susceptible to hypoxic stress. Transcriptomics and metabolomics analyses of gill and revealed that the parathyroid hormone pathway (ko04928) was activated in the gills of M. amblycephala under hypoxic stress. The expression of parathyroid-related genes was upregulated in the hypoxia-sensitive group. However, the expression of parathyroid-related genes in the hypoxia-tolerant group was maintained at a lower level, thus indicating that their ability to cope with the hypoxia environment was stronger. Collectively, the study demonstrated that parathyroid hormone-related genes are involved in the hypoxia response of M. amblycephala, thus providing novel insights on molecular breeding to resist hypoxia.