Low-level MMS treatment of S.cerevisiae

The cellular response to treatment with DNA-damaging substances at low concentrations which are genotoxic but do not have a strong cytotoxic effect are of special interest. In addition, environmental variations that influence growth conditions, e.g. different media, and individual fitness, e.g. different strains, are likely to influence and modulate the adverse effects of individual DNA damaging substances. At sub-cytotoxic levels, DNA damaging substances play an important role in the accumulation of genomic mutations. In longer living organisms, like humans and other mammals, exposure to DNA damaging substances over extended period of time is a critical factor that contributes to the development of various diseases and in particular of tumors. The aim of our work was to study how strain background and growth conditions influence respond to DNA damage caused by low doses of MMS and which part of these changes is responsible for their sensitivity to toxic conditions. We analyzed sensitivity of two yeast strains FF18984 and BY4742 to MMS in media with limited and full nutrient availability. Keywords: Yeast, S.cerevisiae, MMS, stress response, DNA damage YPD and F1 media were inoculated with overnight pre-cultures and grown at 30°C to mid log-phase (OD600 0.6 to 0.8). Cultures were split into three parts: the first aliquot was mock-treated and used as control; the second and third aliquots were treated with low concentration of MMS (0.00125% and 0.0125%). All cultures were incubated at 30° C. Samples were collected after 30 min and 1h incubation. The total of 14 samples were analysed. With the FF18984 strain experiments were done in minimal (F1) and full (YPD) medium with both MMS concentrations (0.00125% and 0.0125%) for 30 min and 1h. With the BY4742 strain experiments were done in full (YPD) medium with 0.0125% MMS for 1h. As a reference we used mock-treated samples from the same medium and the same time point.