Calcium has protective impact on cadmium-induced toxicity in lichens.

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.

Morphophysiological variation and metal concentration in the thallus of Parmotrema tinctorum (Despr. ex Nyl.) Hale between urban and forest areas in the subtropical region of Brazil.

Anthropic activities such as the emission of pollutants resulting from industrial and agropastoral activities promote several changes in urban and forest areas. Lichens are organisms that are used in air quality evaluations due to their sensitivity to these changes. The aim of this study is to analyze the presence of morphophysiological damages and the metal concentration in samples of the lichen Parmotrema tinctorum, in urban and forest areas, checking for possible parameter variations between these areas, in the different matrices and seasons in the Southern region of Brazil. Six areas were selected (urban and forest), assigned to the rural/urban and urban/industrial matrices belonging to the watershed of the Rio dos Sinos, Brazil. The following parameters were analyzed: Index of photobiont vitality (IPV), photosynthetic pigments (chlorophyll, carotene, and pheophytin) and metals (Cu, Cr, Zn, Pb, and Ni) in the thallus of the lichen. The data were analyzed by an ANOVA one way, Pearson correlation test, and principal component analysis (PCA). Variations in the morphophysiological parameters were recorded in all the areas revealing significant differences. The lowest IPV values and highest concentration of metals were recorded in the urban environment, while low chlorophyll levels were found in the forest areas. The PCA showed a distinction between the areas and the season. The level of urbanization, vehicle traffic, and the weather conditions might have influenced the results. The use of P. tinctorum, the index of photobiont vitality and chlorophyll and pheophytin content, has proved to be an efficient tool to diagnose the air quality in the areas analyzed, allowing its use as a model in air monitoring studies, both in urban and forest areas, as well as in distinct matrices in the subtropical region.

Ecophysiological and ultrastructural effects of dust pollution in lichens exposed around a cement plant (SW Slovakia).

The study investigated the ecophysiological and ultrastructural effects of dust pollution from a cement industry in the lichen species Evernia prunastri and Xanthoria parietina, which were exposed for 30, 90 and 180 days around a cement mill, two quarries, and inhabited and agricultural sites in SW Slovakia. The results showed that dust deposition from quarrying activities and cement works at the cement mill (mainly enriched in Ca, Fe and Ti) significantly affected the photosynthetic apparatus of E. prunastri (sensitive to dust and habitat eutrophication), while X. parietina (tolerant to dust and habitat eutrophication) adapted to the new environment. The length of the exposure strongly affected the vitality of the mycobiont (measured as dehydrogenase activity) in transplanted lichens. Dust deposition led to ultrastructural alterations, including lipid droplets increase, swelling of cellular components, thylakoid degeneration and sometimes plasmolysis, which, on the whole, gave the cells an aged appearance. Photosynthetic parameters deserve further attention as potential indicators for monitoring early biological symptoms of the air pollution caused during cement production.