Multi-omics integrative analysis reveals the molecular mechanisms of muscle adaptive changes in largemouth bass (Micropterus salmoides) under water flow stress in recirculating aquaculture

To elucidate the molecular mechanisms underlying changes in muscle quality of largemouth bass ( Micropterus salmoides) under water flow stress, a 90-day experiment was conducted. A total of 270 fish were randomly assigned to three groups, each comprising three replicates with 30 fish per tank: sustained exercise (SE), interval exercise (IE), and control (CG). Dorsal white muscle samples were collected for transcriptomic and metabolomic analyses. Transcriptomic sequencing identified 395 differentially expressed genes (DEGs) between IE and CG (207 upregulated, 188 downregulated) and 353 DEGs between SE and CG (152 upregulated, 201 down- regulated). Metabolomic analysis revealed 113 metabolites upregulated and 68 downregulated in IE, whereas 219 metabolites were upregulated and 172 downregulated in SE compared to CG. Integrated transcriptomic and metabolomic analyses suggest that water flow stress enhances muscle quality in largemouth bass through several key pathways, including the Apelin signaling pathway, the calcium signaling pathway, and the taurine and hypotaurine metabolism pathways. Notably, the upregulation of sphingosine 1-phosphate in the Apelin and calcium signaling pathways contributes to muscle function stability and overall health. Similarly, the upregulation of pyruvate and taurine in the taurine and hypotaurine metabolism pathway indicates enhanced energy metabolism and antioxidant responses during sustained exercise, enabling muscles to meet energy demands and mitigate oxidative stress caused by intense exercise. These findings provide valuable insights into the molecular mechanisms by which water flow stress improves muscle quality in largemouth bass. This research serves as a scientific reference for optimizing muscle quality in largemouth bass within recirculating aquaculture systems (RAS).