Cadmium accumulation and its effects on intracellular ion pools in a brewing strain of Saccharomyces cerevisiae |
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Authors: | K J Blackwell J M Tobin |
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Institution: | (1) School of Biotechnology, Dublin City University, Dublin 9, Ireland, IE |
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Abstract: | The presence of glucose resulted in a two- to three-fold increase in levels of Cd2+accumulated by Saccharomyces cerevisiae after 5 h compared with those observed in the absence of glucose. However, time-dependent Cd2+ uptake continued in the absence of glucose over 5 h, resulting in an appreciable increase in cellular Cd2+levels. Substantial K+ efflux but little Mg2+ and negligible Ca2+release was observed. Cell fractionation revealed that the bulk of intracellular Cd2+ was located in the vacuolar (25%) and bound (60%) fractions. Accumulation of Cd2+ ions impacted most noticeably on K+ rather than Mg2+ levels in intracellular compartments. Cytoplasmic and particularly vacuolar K+ levels decreased as Cd2+ sequestration continued resulting in increased extracellular levels. In contrast, corresponding intracellular Mg2+ pools were only modestly affected with a slight increase and decrease observed in the cytoplasmic and vacuolar fractions
respectively. However, levels of bound Mg2+ decreased in response to continued Cd2+ accumulation.
Received 07 March 1999/ Accepted in revised form 26 June 1999 |
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Keywords: | : cadmium magnesium potassium intracellular localisation Saccharomyces cerevisiae |
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