Acute hypoxia and reoxygenation alters glucose and lipid metabolic patterns in Hulong hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

Abstract

Dissolved oxygen (DO) is crucial for fish's biological functions, affecting metabolism, growth, and survival. Intensive aquaculture and live fish transportation, prevalent in the growing live fish market, often expose Hulong hybrid groupers (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) to acute hypoxic stress. This study explores the impact of acute hypoxia and subsequent reoxygenation on these groupers, focusing on their metabolic response and the underlying mechanisms in different tissues. By inducing acute hypoxic stress until mobility loss and then allowing recovery to normal DO levels, we comprehensively assessed glycolipid metabolism using RNA-seq to map regulatory networks in stress and recovery phases. This revealed significant transcriptional regulation related to hypoxic stress and glycolipid metabolism, with pathways like Insulin, HIF-1, FoxO, and cAMP playing key roles. Gill and brain tissues showed rapid changes, with significant upregulation in genes like irs, pi3k, hif-1α, and hk, whereas the liver had a more subdued response, upregulating genes linked to glycolipid metabolism like gdpd5 and amy1. During reoxygenation, lipid metabolism genes were downregulated in gills and brain, while the liver showed enhanced lipid oxidation, upregulating genes like apoa1 and fabp3, suggesting a metabolic shift from anaerobic to aerobic processes. These findings illuminate the molecular mechanisms of grouper adaptation to DO fluctuations, offering insights to mitigate acute hypoxia damage in aquaculture.