Oxidative and nitrosative metabolism modifications by seasonality and toxins exposition in the bivalve Mytilus edulis platensis

GONZÁLEZ PAULA M.; PUNTARULO, S.

Córdoba

Congreso; VI Congreso Argentino de la Sociedad de Toxicología y Química Ambiental de Argentina (SETAC, Capítulo Argentino); 2016

SETAC

The hypothesis of the work was that oxidative and nitrosative metabolism in the bivalve Mytilus edulis platensis is modified by the presence of planktonictoxins. Organisms were collected in San Matías Gulf, Argentinean Sea. Thelabile Fe pool (LIP), determined by fluorescence, was not significantly different in DG fromanimals collected in summer and winter, but was 2.3-fold increased in samplesfrom spring (in the presence of harmful planktonic toxins) compared to summercollected molluscs. The 2′,7′ dichlorofluorescein diacetate(DCFH-DA) oxidation rate (measured spectrophotometrically) and the ascorbylradical/ascorbate content ratio are indicators of the hydrophilic oxidativecondition. On the other hand, the lipid radical/α-tocopherol content ratiois an indicator of the oxidative condition in the lipophilic medium. Radical contentwas analyzed by electronic paramagnetic resonance (EPR) and non-enzymaticantioxidant content by HPLC. The three parameters showed no significant differences betweensamples collected in winter and summer. However, spring collected samplesshowed significantly higher DCFH-DAoxidation rate and oxidative ratios in comparison to DG from bivalves collectedin summer. Enzymatic antioxidants were spectrophotometrically assayed. Superoxide dismutase andglutathione S-transferase activities decreased by 75 and 89% in winter, and 93and 30% in spring, respectively, compared to samples collected in summer.Catalase activity was increased by 3.8-fold in winter compared to summervalues, and was not changed between spring and summer. Nitrosative metabolismwas estimated by nitrate plus nitrite content (spectrophotometricallyevaluated) and nitric oxide content (measured by EPR). Nitrite plus nitratecontent was not altered among samples collected in the three seasons, butnitric oxide content was increased by 8.5- and 2.7-fold in samples from winterand spring than in summer, respectively. The data presented herestrongly suggested that under seasonality conditions the overallnetwork of oxidants and antioxidants seems to be adequately controlled to keepsteady state concentrations of damaging reactive species far from dangerouslevels. However, in the presence of harmful planktonic toxins, the bivalveswere facing oxidative and nitrosative stress.