Ca2+ homeostasis and redox balance in Antarctic sea organisms: effects of temperature and of environmental contaminants

In this research, three lines of investigation were pursued. (1) In vivo ef fects of temperature and H2O2 were evaluated in the limpet Nacella concinna . Population of reactive oxygen species was assessed with the dihydrorhodam ine 123 fluorescent probe, lysosome alterations with histochemical techniqu es, and antioxidant responses through superoxide dismutase and catalase ass ays. Data suggest that Nacella spring migrations to intertidal levels, wher e rises in temperature occur, induce oxidative stress and antioxidant respo nse. (2) In the scallop Adamussium colbecki, the sarcoplasmic reticulum Ca2 + ATPase was characterized and heavy metal effects were assessed. An IC50 o f 0.9 mu M was found for Hg2+ and of 3 mu M for Cd2+. (3) Effects of Cu2+, Cd2+, and Hg2+ (2.5 mu M), and of temperature on Ca2+ homoeostasis and cell viability were assessed in the ciliate Euplotes focardii. Ca2+ homeostasis and cell viability were altered by Hg2+ at a temperature of 0 degrees C an d above, and by Cu2+ and Cd2+ at 10 degrees C and above. Temperature alone was effective at 20 degrees and 30 degrees C, suggesting that rises in temp erature cause an increased cell sensitivity to environmental contaminants.