Golden pompano (Trachinotus blochii) adapts to acute hypoxic stress by altering the preferred mode of energy metabolism

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The golden pompano (Trachinotus blochii) is becoming increasingly popular among consumers for its delicate meat and high nutritional value. High farming density, eutrophication, and high-temperature conditions increase the probability of hypoxia and thus hypoxic stress, which poses a major challenge for the future development of golden pompano aquaculture. Here, we simulated severe hypoxic stress to distinguish hypoxia-tolerant and hypoxia-sensitive individuals from hundreds of fish. We then used next-generation sequencing to analyze the mRNA expression profiles of the brains and livers under hypoxia to identify the causes of differences in hypoxia tolerance among different groups. The pathways involved in highly expressed genes in the brain were mainly related to signal transduction, endocrine function, and environmental information processing, while the pathways involved in highly expressed genes in the liver were mainly related to metabolism. Under hypoxic conditions, the degradation of liver glycogen in the hypoxia-tolerant group was inhibited under hypoxia. However, in the hypoxia-intolerant group, glycogen decomposition is not inhibited, glucose consumption increases, and there is no tendency to convert to lipid metabolism, leading to metabolic disorders. In the process of adapting to hypoxia, fish first use anaerobic glycolysis to compensate for the lack of energy due to hypoxia. However, as the stress persists, glycolysis is inhibited, and lipid metabolism becomes the preferred mode of energy metabolism; specifically, acetyl-CoA may be produced through lipid metabolism in the hypoxia-tolerant group and then participate in the tricarboxylic acid cycle to provide energy. Death in the hypoxia-intolerant group may stem from the metabolic disorder of glucose and lipid homeostasis. Although additional research is needed to confirm these possibilities, our findings suggest that converting the preferred way of energy metabolism to lipid metabolism may be a way for fish to adapt to acute hypoxic stress.