chlorophyll-a and physcione

Comparisons were made between the content of Al, Cd, Cu, Fe, Mn, Pb, Sb and Zn in thalli of the lichen Xanthoria parietina and selected physiological processes. Assimilation pigments, activity of photosystem II, parietin, reactive substances produced using thiobarbituric acid (TBA) and CO(2) gas exchange were measured in order to assess tolerance to atmospheric sources of pollution. As expected, lichen thalli accumulated high amounts of the measured elements in relation to distance from pollution sources in Kosice, Slovak Republic (US Steel factory and vehicular traffic in the city center). However, except for TBA reactive substances production and to some extent CO(2) gas exchange at the most polluted station, none of the tested physiological parameters showed a clear correlation between accumulation of elements and physiological damage. This reflected a high degree of pollution tolerance in this lichen and corresponded with its high abundance in Kosice.

Topics: Carbon Dioxide; Carotenoids; Chlorophyll; Chlorophyll A; Emodin; Environmental Monitoring; Environmental Pollutants; Lichens; Metals; Photosystem II Protein Complex; Slovakia; Thiobarbituric Acid Reactive Substances

This study reports UV screening pigments in the upper cortices of two widespread lichens collected in three sun-exposed locations along a latitudinal gradient from the Arctic lowland to alpine sites of the Central European Alps. Populations from the Alps receive 3-5 times higher UV-B irradiance than their Arctic counterparts from Svalbard because of latitudinal and altitudinal gradients in UV-B irradiance. In Cetraria islandica, the screening capacity of melanin in the upper cortices was assessed by direct measurements of cortical transmittance (250-1,000 nm). A comparison of cortical transmittances in brown sun-exposed and pale shade-adapted forest C. islandica thalli showed that fungal melanins strongly absorb both UV-B and photosynthetically active radiation (PAR). For Xanthoria elegans cortical UV-B absorbing pigments, mainly the orange parietin, were extracted and quantified. Field experiments with extracted, parietin-deficient X. elegans thalli cultivated under various filters showed that UV-B was essential for the induction of parietin synthesis. The parietin resynthesis in these parietin-deficient samples increased with decreasing latitude of their location in which they had been sampled, which may imply that the synthesis of pigments is habitat specific. However, no latitudinal gradient in cortical screening capacity was detected for any of the two species investigated in the field. This implies that Arctic populations maintain a high level of screening pigments in spite of low ambient UV-B, and that the studied lichen species presumably may tolerate an increase in UV-B radiation due to the predicted thinning of the ozone layer over polar areas.

Topics: Analysis of Variance; Arctic Regions; Chlorophyll; Chlorophyll A; Emodin; Geography; Lichens; Melanins; Pigmentation; Species Specificity; Sunlight; Ultraviolet Rays