Estimation of oxidative stress in Saccharomyces cerevisae with fluorescent probes

Oxidation of dichlorofluorescin and dihydrofluorescin and transport of their oxidation products were studied in Saccharomyces cerevisiae cells given diacetates of these compounds. It was found that addition of peroxidase significantly accelerates the formation of dichlorofluorescein and fluorescein, indicating that peroxidase activity may be a limiting factor in studies of cellular oxidation using these probes. A significant leakage of dichlorofluorescin and dihydrofluorescin, and of their oxidized forms from the yeast cells, was found, without any apparent lag period. This phenomenon complicates interpretation of data obtained with the fluorescent precursors used but, on the other hand, points to the possibility of using measurements of dichlorofluorescein or fluorescein in the extracellular medium for studies of cellular oxidation processes.