Transcriptomic and Ultrastructural Analyses Reveal the Mechanisms of Accelerated Depuration Induced by Phyllodium pulchellum Extract in the Freshwater Snail Bellamya purificata

The commercial viability of B. purificata relies on efficient depuration. While P. pulchellum extract dramatically accelerates this process, its physiological and molecular mechanisms remain unknown. To address this, we integrated behavioural, histological, ultrastructural, and transcriptomic (RNA-seq) analyses to characterize the acute stress and subsequent recovery phases of B. purificata exposed to the botanical extract. Extract exposure induced severe neuromuscular hyperextension response, with histological analysis revealing acute interstitial oedema and neuronal chromatolysis. This structural damage caused sustained cephalopodium extension and muscle fibre uncoupling. Transcriptomic profiling linked this neuromuscular dysfunction to conserved calcium-dependent adrenergic signalling modules and profound endogenous neuroendocrine disruption. The extract also induced cellular stress, downregulating the apoptosis inhibitor BIRC7 and eliciting transcriptomic signatures consistent with a DNA damage response. Crucially, during the short-term recovery phase, surviving tissues mounted a robust transcriptomic repair response. The snails systemically suppressed the cell cycle via MCM2-6 downregulation while upregulating GADD45 and RAD54B, suggesting a prioritization of genomic repair alongside partial morphological reorganization. Ultimately, P. pulchellum accelerates depuration via acute phytochemical stress and neuromuscular dysfunction. Importantly, this stress is accompanied by a highly coordinated transcriptomic repair response and partial short-term restoration, providing foundational molecular insights essential for evaluating and optimizing botanical depuration protocols.