Antioxidant responses and lipid peroxidation in gills and hepatopancreas of the mussel Perna viridis upon exposure to the red-tide organism Chattonella marina and hydrogen peroxide

In this study, we investigated the production of hydrogen peroxide (H₂O₂) by the red-tide organism Chattonella marina. Subsequently, we examined the antioxidant responses as well as lipid peroxidation in gills and hepatopancreas of the mussel Perna viridis upon exposure to C. marina at environmentally realistic concentrations (10³ and 10⁴ cells ml⁻¹). Despite the extracellular levels of H₂O₂ generated were up to ∼0.5 (at 10³ cells ml⁻¹) and 20 μM (at 10⁴ cells ml⁻¹), no significant differences could be observed in any of the examined biochemical parameters (i.e. catalase (CAT), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GR) and lipid peroxidation (LPO)) in mussels between treatment and control groups. In another experiment, where mussels were exposed to H₂O₂, no responses were induced at the concentration up to 0.5 mM. These data collectively indicate that the production of H₂O₂ by C. marina is not high enough to elicit antioxidant responses in mussels. As such, reactive oxygen species (ROS) is unlikely to be an important toxicological mechanism of C. marina.