Impact on nitrosative/oxidative stress of the exposure of the bivalve Mytilus edulis platensis to biotoxins

GONZÁLEZ P.M.; PUNTARULO S.

Mar del Plata

Congreso; VIII Congreso Argentino de la Sociedad de Toxicología y Química Ambiental, SETAC Capítulo Argentino; 2022

      Actual changes in environmental conditions, mainly byanthropogenic causes, are leading to larger toxic events increasing globaloccurrence of harmful algae blooms (HAB). Even more, increasing seawater temperatures,because of the global climate change, contribute to modifications in the trophicstructure, species composition, metabolic stress and function of aquaticecosystems. The objective of this work was to analyze the nitrosative/oxidativemetabolism during spring in the presence of biotoxins generated by HAB, ascompared to other seasons (summer and winter) in the bivalve Mytilus edulisplatensis. This animal is one of the most important economic sources in theregion, in spite of being a common vector of toxic microorganisms. Digestive glands (DG, as a primary target tissue) andhemocytes (as the main effectors of the immune system) were isolated frommussels of the Argentinean Sea. The nitrosative metabolism in the DG, evaluatedas nitric oxide (NO, measured by EPR) content, was 8.5- and 2.7-fold higher insamples isolated from winter and spring than in summer molluscs, respectively.However, in hemocytes, NO, nitro-tyrosine content (measured by western blot) andsuperoxide anion generation rate (measured spectrophotometrically) were 3-foldhigher in spring as compared to winter and summer samples. On the other hand, inDG, 2′,7′dichlorofluorescein diacetate (DCFH-DA) oxidation rate (a reactivespecies generation rate technique measured fluorometrically), and the ratios ascorbylradical (A●, measured by EPR)/ascorbate content (measured by HPLC) andlipid radical (LR●, measured by EPR)/α-tocopherol content (measuredby HPLC) were significantly higher between samples collected during spring withthose of summer and winter. In the hemocytes DCFH-DA oxidation rate wasincreased by 2.5- and 8.3-fold during spring and summer, respectively, ascompared to winter samples. The LR● content in spring was 140 and50% higher as compared to winter and summer cells, respectively. Even though these results showed the lack of vital effectsunder natural seasonality conditions, the nitrosative stress was clearlytrigger by biotoxins in the hemocytes as compared to the DG. In the DG, theoxidative stress was more significantly induced, as compared to the hemocytes.Then, biotoxins seem as a contributing factor to affect not only reactiveoxygen species generation, but also nitrogen metabolism in bivalves.