Molecular Insights into Hydrogen Sulfide Defense: A Tissue-Resolved Transcriptomic Study in the Crab Eriocheir sinensis

The increasing threat of multiple abiotic stressors in aquatic ecosystems has raised significant ecological concerns. While molecular responses to hydrogen sulfide (H₂S) have been studied in some aquatic species, the tissue-specific regulatory mechanisms in the Chinese mitten crab (Eriocheir sinensis) remain largely unexplored. Here, we investigated the tissue-specific transcriptomic responses of E. sinensis to H₂S exposure (0, 0.1, and 5 mg/L) across four tissues: hepatopancreas, gill, muscle, and intestine. Our analysis revealed significant enrichment of serine endopeptidase activity and tyrosine metabolism pathways, highlighting their key role in mitigating H₂S-induced damage. Furthermore, high-concentration H₂S exposure markedly up-regulated antioxidant enzyme activities (SOD, CAT, GSH-PX) and related genes (SOD1, GPX1, HO-1), whereas cytochrome c oxidase (COX) expression was suppressed, indicating concurrent oxidative stress and disruption of energy metabolism. These findings provide novel molecular insights into H₂S toxicity in crustaceans and hold valuable implications for both ecological risk assessment and sustainable aquaculture practices.