Oxidative and nitrosative metabolism in digestive glands of the bivalve Mytilus edulis platensis

GONZÁLEZ PAULA M.; PUNTARULO S.

La Paz

Conferencia; Second International Conference on Oxidative Stress in Aquatic Ecosystems; 2015

Centro de Investigaciones Biológicas del Noroeste

The hypothesis of the work was that oxidative and nitrosative cellularcondition in Mytilus edulis platensisis modified by specific factors linked to seasonal stress. Digestive gland (DG)were isolated from specimens collected in the Argentinean Sea during the 2012 (summerand winter) and 2013 (spring, red tide season) time. The labile Fe pool (LIP, determinedby fluorescence) was different in DG from summer and winter (30±2 and 41±5 pmolmg/FW, respectively); however, the LIP always represented a low percentage ofthe total Fe content (5%). Enzymatic antioxidants, spectrophotometricallyassayed, were either decreased (i.e catalase activity) or increased (i.esuperoxide dismutase and glutathione transferase) in DG sampled in summer ascompared to samples collected in winter time. The oxidation of the 2′,7′dichlorofluorescein diacetate (DCF-DA), the ascorbyl radical/ascorbate content,and the lipid radical/a-tocopherolcontent ratios are indicators of the general, hydrophilic and lipophilicoxidative condition, respectively. Dye oxidation was measuredspectrophotometrically, radical content by Electron Spin Resonance (ESR) and non-enzymaticantioxidant content by HPLC: These indexes showed no significant differencesbetween samples collected in winter and summer. Nitrosative metabolism wasestimated by nitrate plus nitrite content (spectrophotometrically evaluated),and nitric oxide content (measured by ESR). Both parameters were significantlyhigher in samples collected in winter as compared to values in samplescollected in summer time (2.3- and 9-fold higher, respectively). Upon the redtide, collected samples showed that the LIP represented 20% of the total Fecontent, with higher oxidation rate of DCF-DA, and oxidative ratios, as compared to samples collected insummer, and a nitric oxide contentintermediate between summer and winter. These results suggested that cellular Fe-dependentdamage is tightly controlled, as shown by the lack of effect of seasonality onthe oxidative indexes. However, under more stressful conditions, such asexposure to toxins during red tide, both oxidative and nitrosative metabolismare affected.