Mécanismes physiologiques impliqués dans la contamination et la lente dépuration de la toxine amnésiante, l'acide domoïque, chez la coquille Saint-Jacques Pecten maximus

Abstract

Domoic acid (DA) is a neurotoxin produced by diatoms of the genus Pseudo- nitzschia and is responsible for Amnesic Shellfish Poisoning (ASP) in humans. The king scallop Pecten maximus is a high valuable resource frequently exposed to Pseudo- nitzschia blooms, and capable of accumulating high amounts of DA, retaining it for months or even a few years, compared to other fast- depurator bivalves. This work aimed to decipher what are the main physiological mechanisms involved in the kinetics of accumulation and slow depuration of DA in the scallop P. maximus in comparison to fast-depurator species. The development of an anti-DA immunohistochemical technique allowed to visualize that part of the DA-signal was trapped within autophagosomes distributed within the cytoplasm of the scallops digestive cells.The subcellular time-tracking of DA revealed a strong implication of autophagy in slow DA- depuration, which did not seem to occur as much in other fast depurating species. Furthermore, an in vitro exposure of digestive gland slices of scallops P. maximus and mussels Mytilus edulis to dissolved DA revealed a strong upregulation of autophagy-related transcripts in the scallops, and an overexpression of glutamate receptors (GR) and membrane solute-carriers (SLC) genes in mussels, which could support differences in recognition and assimilation/excretion of DA between slow and fast depurators. This work provides new evidence about physiological mechanisms involved in the long retention of DA in P. maximus and represents the baseline to explore procedures to accelerate decontamination in this species.

Part of CIRS Nexus · Curated by Lauren Lowenstein, The Biotoxin Lady