Genotoxic Chromatin Changes in Schizosaccharomyces Pombe Induced by Hexavalent chromium (CrVI) Ions
Based on their MIC50 values Cr(VI) turned out to 15-times more toxic than Cr(III) in S. pombe estimated to be 15 and 225 µM, respectively. Major focus of this chapter is placed on large-scale chromatin structures of fungal nuclei, isolated from protoplasts of the fission yeast Schizosaccharomyces pombe and visualized for the first time by fluorescence microscopy . Although, the pattern of chromosome condensation was similar to mammalian cells, but less compact and resembled more to that of Drosophila. S. pombe cells were treated with hexavalent chromate ions (CrVI) in a concentration-dependent manner and chromatin structures were analysed. Results show that subtoxic levels of Cr(VI) (<1 µM) did not cause significant chromatin changes. Early signs of apoptotic cytotoxicity were observed at 10 µM Cr(VI) concentration. Nuclear changes caused by Cr(VI) in the concentration range between 10 and 50 µM were characterized by apoptosis seen as broken nuclei and apoptotic bodies. High concentration of Cr(VI) ions (75–200 µM) initiated necrotic nuclear changes, with focal condensation of chromatin and the formation of extremely enlarged nuclei that were in a highly decondensed fibrillary state. The necrotic enlargement of fibrillary nuclei was dependent on the Cr(VI) concentration.
KeywordsChromatin Structure Fission Yeast Genotoxic Agent Indian Muntjac Chromatin Change
This work was supported by the OTKA grant T042762 (G.B.).
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