Effects of Mercury on Dictyostelium discoideum: Proteomics Reveals the Molecular Mechanisms of Physiological Adaptation and Toxicity

Dictyostelium discoideum amoebae were exposed to Hg 2 mu M corresponding to a sublethal concentration and Hg 10 mu M with the first effects on mortality and replication rate. A total of 900 spots were visualized by 2-DE electrophoresis. Two-hundred fifty single proteins were identified by mass spectrometry. Low Hg concentration (2 mu M) treatment induced up-regulation of 13 spots, mainly involved in oxidative stress response/detoxification, oxidoreductase activity, and metabolic processes. High Hg concentration (10 mu M) treatment showed a different PES with 12 proteins downregulated and only two up-regulated, mainly involved in cellular metabolic processes, metal ion binding, and transferase activity. The analyses for the carbonylation show no changes after 2 mu M Hg2+ treatment and 13 differentially carbonylated proteins after 10 mu M Hg2+ involved in a broad range of cellular processes. Our findings provide insight into the mechanisms of physiological adaptation and toxicity to a low and an high mercury concentration, respectively, of Dictyostelium amoebae.