Physiological and transcriptomic analyses reveal temperature-dependent regulation of stress response, protein synthesis and metabolic reprogramming in juvenile mandarin fish (Siniperca chuatsi) under simulated transport.

With the rise of long-distance transport in aquaculture, temperature has become a key factor affecting juvenile fish survival and health. However, their molecular adaptation to transport temperature is not well understood. In this study, physiological and transcriptomic analyses were conducted to investigate the effects of transport temperatures on juvenile Siniperca chuatsi. With 25 °C non-transported fish as the control (C25), three transport temperature groups were established: transport at 15 °C (T15), transport at 25 °C (T25) and transport at 30 °C (T30). Comparative analyses were then performed between each transport group and the control (T15 vs. C25, T25 vs. C25 and T30 vs. C25). Liver damage became progressively more severe with increasing transport temperature, reaching its peak at T30 with pronounced edema and necrosis. Transcriptomic analysis identified over 5463 DEGs and three WGCNA modules significantly associated with temperature variation. Hub genes in the MEdarkseagreen4 module (T30) were enriched in lysosomal activity, calcium signaling and cytoskeletal regulation, indicating disrupted cellular homeostasis as a key driver of liver damage. At T15, the MEcyan module was enriched with upregulated hub genes for ribosome function and fatty acid metabolism, indicating boosted protein synthesis and energy use under low-temperature transport. In the T25, hub genes in the MEpalevioletred3 WGCNA module showed downregulation of oxidative phosphorylation and insulin signaling pathways, indicating a suppression of energy metabolism and growth signaling as part of a stress-adaptive strategy. These results deepen our understanding of the molecular mechanisms underlying temperature adaptation in eurythermal fish during simulated transport.