Molecular insights into hydrogen sulfide defense: A tissue-resolved transcriptomic study in the crab Eriocheir sinensis.

The increasing prevalence of multiple abiotic stressors in aquatic ecosystems has raised significant ecological concerns. While molecular responses to hydrogen sulfide (H₂S) have been investigated in some aquatic species, the tissue-specific regulatory mechanisms in the Chinese mitten crab (Eriocheir sinensis) remain poorly understood. Following a 48-h exposure to varying concentrations of H₂S (0, 0.1, and 5 mg/L), four key tissues-hepatopancreas, gill, muscle, and intestine-were collected for an integrated analysis of transcriptomic sequencing and physiological/biochemical assays. Our results demonstrated significant enrichment of pathways related to serine endopeptidase activity and tyrosine metabolism in affected tissues, highlighting their potential role in mitigating H₂S-induced damage. Furthermore, high-concentration H₂S exposure substantially elevated the activities of antioxidant enzymes (SOD, CAT, GSH-PX) and up-regulated the expression of associated genes (SOD1, GPX1, HO-1), while simultaneously suppressing cytochrome c oxidase expression. These coordinated changes indicate that H₂S toxicity triggers pronounced oxidative stress alongside disrupted energy metabolism. The present study provides novel experimental insights into the molecular mechanisms of H₂S toxicity in crustaceans and offers a scientific foundation for ecological risk assessment and sustainable aquaculture management.