Eventual protective action of calcium (Ca, 100 or 1000 μM) against cadmium (Cd, 10 or 100 μM) toxicity in common lichen Hypogymnia physodes after 24 h of exposure was studied. Total Cd reached 482 and 2801 μg/g DW in 10 and 100 μM Cd treatments while Ca content reached over 23 mg/g DW in 1000 μM Ca treatment. Ca suppressed Cd accumulation by 23 and 38% in total fraction and completely in absorbed fraction. Fluorescence microscopy of Cd and Ca ions revealed good correlation with quantitative data. Cd stimulated increase in ROS formation and lipid peroxidation as detected using fluorescent reagents and quantification of H2O2 while co-application of Ca suppressed these effects. Formation of nitric oxide was mainly affected by cadmium. Cd depleted amount of amino acids but proteins or phenols remained unaffected by Cd or Ca. On the contrary, sum of thiols, reduced glutathione and ascorbic acid were depleted by Cd but reversed mainly by higher Ca dose. Among organic acids, only Cd-induced depletion of citric acid content was reversed by Ca. Data indicate that ameliorative effect of Ca under Cd excess in lichens is comparable with effect in plants and metabolic responses in various life lineages are discussed.

Department of Analytical Chemistry Medical University of Lublin Chodźki 4a 20 093 Lublin Poland

Department of Biology University of Trnava Priemyselná 4 918 43 Trnava Slovak Republic

Department of Physiology Faculty of Medicine Masaryk University Kamenice 753 5 625 00 Brno Czech Republic

Department of Plant Physiology and Biophysics Institute of Biological Science Maria Curie Skłodowska University Akademicka 19 20 033 Lublin Poland

Faculty of Education University of Trnava Priemyselná 4 918 43 Trnava Slovak Republic

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Mercury Content and Amelioration of Its Toxicity by Nitric Oxide in Lichens