Cd and Ni modulate fatty acid composition and oxidative status in the freshwater mussel Anodonta cygnea

To determine the different effects of metal ions with various chemical properties on freshwater bivalve molluscs, the effect of Cd and Ni on Anodonta cygnea was examined. Aside from highlighting some indicators of oxidative damage (i.e. lipid peroxidation product content) and antioxidant defence (i.e. the content of reduced glutathione and the activity of catalase and glutathione-S-transferase), we also analysed the composition of the phospholipid fatty acids in the gills of the mussels. The mussels were exposed to 10, 50 and 100 μg/L of Cd and Ni (the control was no metal exposure) for 1 and 3 days, respectively. Then, the biochemical parameters of the mussel gills, such as the fatty acid composition, the conjugated dienes, thiobarbituric acid reactive species products and reduced glutathione contents and the glutathione-S-transferase and catalase activities were analysed. The one-day effect of Cd induced a decrease in the linoleic acid content and an increase in the lipid peroxidation products and glutathione-S-transferase activity. The one-day Ni exposure caused an increase in the arachidonic acid content without any elevation of the activity of the studied antioxidant enzymes. On day 3, the presence of Cd caused an increase in the linoleic and arachidonic acid content and catalase activity, whereas no changes in the fatty acid composition and antioxidant enzyme activity were noted in the presence of Ni. Different metabolic changes occur with the studied metals (Cd and Ni) in freshwater A. cygnea. Therefore, various mechanisms are involved in their defensive metabolic responses.