Gene network analysis reveals the responsive cascades of scallop (Patinopecten yessoensis) exposed to toxic Alexandrium catenella.

As filter-feeding bivalves, scallops exhibit remarkable tolerance to paralytic shellfish toxins (PSTs) produced by Alexandrium dinoflagellates, yet the molecular mechanisms enabling concurrent PST accumulation and physiological resilience remain poorly understood. Here, we integrated transcriptomics and weighted gene co-expression network analysis (WGCNA) to dissect dynamic gene networks in scallop digestive glands during a 15-day exposure to PST-producing algae. We identified eight responsive modules, with the hub module M4 coordinating all phases of xenobiotic metabolism: phase I oxidation (CYP enzymes), phase II conjugation (GST/GGT), and phase III efflux (MRP transporters). Module M19 uniquely modulated glutathione (GSH) homeostasis by suppressing tyrosinase (TYR) during peak detoxification (Days 5-10) to prioritize toxin conjugation, followed by TYR activation to reset GSH levels post-exposure (Day 15). Notably, neural-related modules (M3, M6) counteracted PST neurotoxicity by restoring ion homeostasis through epithelial sodium channels (SCNNG) and regulating neurotransmitter dynamics (SLC6, ACH). Crucially, the coordinated interactions between up- and down-regulated modules, as inferred from dynamic gene expression patterns in xenobiotic metabolism, neural homeostasis, and detoxification pathways, collectively suggest a potential role in mitigating PST-producing algae-induced cellular damage. This study reveals a dual-functional gene network in scallop digestive glands that balances PST hyperaccumulation with multi-layered detoxification, providing mechanistic insights into bivalve adaptation to harmful algal blooms.