Transcriptome Analysis Provides New Insight into Apoptosis and Immunosuppression in Procambarus clarkii After...

Acute heat stress frequently causes mass mortality in farmed red swamp crayfish (Procambarus clarkii), yet the mechanisms underlying immune collapse remain poorly understood. We established an acute heat stress model (37 °C, 6 h) and performed an integrative analysis combining hemocyte profiling, redox and immune assays, RNA-seq, and qRT-PCR. Heat stress significantly increased mortality and disrupted the hemocyte system, with a ~25% reduction in total hemocyte count and a selective decline in granular cells. This was associated with severe redox imbalance, evidenced by ROS/H₂O₂ accumulation, suppressed SOD and CAT activities, and lipid peroxidation damage. Transcriptomic analysis revealed 1446 differentially expressed genes, indicating concurrent activation of ER stress and autophagy alongside suppression of energy metabolism. Key gene validation confirmed upregulation of pro-apoptotic factors (CASP3, P53) and ER stress markers (GRP78, XBP1), consistent with hemocyte depletion. These findings provide multi-level evidence that acute heat stress triggers a redox crisis ("oxidative burst-defense suppression"), which in turn activates ER stress and apoptosis, leading to selective loss of granular cells and systemic immune compromise. This study establishes a mechanistic framework for understanding heat-induced mortality in crustaceans and offers a theoretical basis for developing targeted interventions to enhance thermal resilience in crayfish aquaculture.