Multi-omics analysis provides insight into liver metabolism in yellow catfish (Pelteobagrus fulvidraco) under hypoxic stress

Dissolved oxygen is an environmental factor that affects fish survival. Aquatic environments suffer from an increasing oxygen deficiency resulting from global warming and environmental pollution. In this study, we combined high-throughput transcriptome analysis with non-targeted liquid chromatography-mass spectrometrybased metabolome sequencing to assess the metabolic response to hypoxia in the liver of Pelteobagrus fulvidraco. Healthy fish with body weight of 12.39 +/- 1.37 g were subjected to hypoxic conditions at a concentration of 1.02 +/- 0.09 mg/L for durations of 6, 24 and 48 h. Hypoxia exposure increased the content of MDA, lactate, glucose and the level of T -AOC, enhanced the activity of T -SOD, CAT, GPx and LDH, and decreased SDH activity. Histological examination revealed that liver tissue was damaged after exposure, and the degree of damage increased with the prolongation of hypoxia time. In the liver transcriptome, 1527 DEGs were identified, of which 240 were co-identified in the three comparison groups. These DEGs showed significant enrichment in pathways associated with oxidation-reduction and metabolic processes. RT- qPCR confirmed transcriptional induction of metabolismrelated genes in response to hypoxia. Metabolomic results showed that the SDMs were related to amino acid, carbohydrate, and lipid metabolism. Moreover, a conjoint analysis demonstrated an increase in the activity of several key enzymes, such as phosphoenolpyruvate carboxykinase, phospholipid phosphatase 1a, and betainehomocysteine methyltransferase. An integrated regulatory network was observed to be involved in glycine, serine, and threonine metabolism; glycolysis/gluconeogenesis; tricarboxylic acid cycle; protein digestion and absorption; and lipid metabolism in response to hypoxia exposure. Overall, the findings indicated that hypoxia can cause oxidative stress in yellow catfish and that their bodies can resist stress by activating the antioxidant defense system and mobilizing multiple metabolic pathways to meet the energy demand. These results will aid in the development of strategies aimed at mitigating the adverse effects of hypoxic exposure on fish.