The high mountain lakes in the Rila Mountains (Bulgaria) were studied in the years 2000 and 2001 considering the following groups of variables: geography, geology, morphology, hydrology, water chemistry of the pelagial, biomass and size structure of bacterio- phyto- and zooplankton, and occurrence of three fish species. Multivariate analysis (RDA) revealed that the nutrient concentrations in the lakes were significantly influenced by the soil percentage coverage of the catchment area. The explained variation in plankton components (bacterio-, phyto- and zooplankton) and plankton size structure was determined by biological as well as morphometrical and geographical variables. Changes in the Mg2+ and NO3-N concentrations were traced over the period 1993- 2001; the Ca2+ concentration, pH, nutrients, bacterio-, phyto- and zooplankton were monitored in the period 1995-2001. A nutrient decrease accompanied by an increase in size of zooplankton organisms in the period 1995-2001 led to a considerable increase of water transparency in the lakes

SummaryAim: Cytokinesis-block micronucleus (CBMN) assay and its comprehensive variant CBMN cytome assay are cytogenetic methods. CBMN is based on assessment of micronuclei in nucleated cells that have completed only one nuclear division. Besides micronuclei, CBMN cytome assay analyzes additional genotoxic (nucleoplasmic bridges and nuclear buds), cytostatic (nuclear division index), and cytotoxic (amount of necrotic and apoptotic cells) parameters. The aim of this study is to evaluate these parameters in human blood lymphocytes after in vitro irradiation and to assess its contribution to biodosimetry. Material and methods: Human blood from 6 donors was in vitro irradiated by 0, 1, 2, 3, 4, or 5 Gy and cultivated for 72 hours. Blood lymphocytes were stimulated with phytohemagglutinin and their cytokinesis was blocked by cytochalasin B. After cultivation, cultures were hypotonically treated, dropped onto glass slides and stained with Giemsa. Slides were evaluated by microscope. Results: We observed significantly increased amount of micronuclei, nucleoplasmic bridges, and nuclear buds measured in binucleated cells, significantly increased amount of micronuclei measured in mononucleated cells and significantly decreased nuclear division index after irradiation by 1, 2, 3, 4, and 5 Gy. Amount of death cells (apoptotic and necrotic) significantly increased after irradiation by 4 and 5 Gy. Conclusion: Although all parameters assessed by CBMN cytome assay have biodosimetric potential, practically feasible is only evaluation of micronuclei in binucleated cells. This parameter was used to construct in vitro linear-quadratic dose-response calibration curve which could be used as a biodosimetric tool for triage of radiation casualties.

Local values of natural radiation background in soils from unexplored regions in the Eastern Rhodopes were established. The impact of anthropogenic activity as a potential risk for increase in radiation background was assessed. Soil samples from areas near the liquidated lead-zinc mines – Madzharovo, gold mine – Ada Tepe, Krumovgrad, lead-zinc complex – Kardzhali, Neochim – Dimitrovgrad, deposits for extraction of gneiss, marble quarries, etc. were analyzed to study possible contamination. Specific activity of natural radionuclides 210Pb, 238U, 226Ra, 235U, 232Th, 40K and technogenic 137Cs in the studied samples was determined by gamma spectrometric analysis with Multichannel analyzer DSA 1000, production of CANBERRA and HPGe-detector.

Targeting sonic hedgehog pathway in combination with proton radiation or gamma irradiation decreases viability of glioma cell lines .

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