Effects of mercury on Dictyostelium discoideum: proteomics reveals the molecular mechanisms of physiological adaptation and toxicity

Dictyostelium discoideum amoebae were exposed to Hg 2 μM corresponding to a sublethal concentration and Hg 10 μM 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 μM) treatment induced up-regulation of 13 spots, mainly involved in oxidative stress response/detoxification, oxidoreductase activity, and metabolic processes. High Hg concentration (10 μM) 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 μM Hg²⁺ treatment and 13 differentially carbonylated proteins after 10 μM 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.