Yeast cultures in early logarithmic phase (OD 600 $ 0.2) were stressed with H 2 O 2 (0.12-180 mM), menadione (0.05-0.6 mM), cumene hydroperoxide (CHP, 0.1-0.2 mM), tert-butyl hydroperoxide (t-BHP, 1-3 mM), paraquat (0.1-10 mM), diamide (0.2-2 mM) and linoleic acid hydroperoxide (LoaOOH, 0.05-0.2 mM) for 200 min (all reagents from Sigma). Treatment with acetic acid stress was performed as described (29, 30) . Cells were grown in SC media to early exponential stage, shifted to SC media, pH = 3, and treated with 175 mM acetic acid (Sigma) for 200 min. Hyperosmotic shock was achieved by growth of exponential cells in SC complete media containing 60% (wt/wt) glucose (Fluka) or 30% (wt/wt) sorbitol and 2% glucose (Sigma) for 2-8 h (31). Chronological ageing was performed by constant growth of yeast cultures in SC complete medium for 2-16 days (32) . For expression of murine Bax or Bcl-x L proteins, cells were grown to early exponential phase in SC-Leu or SC-Trp, respectively. Expression of murine Bax was induced by shifting the cells grown to early exponential phase in SC-Leu medium containing glucose to SC-Leu medium containing galactose for 6 h. Pre-treatment with ascorbic acid (20 mM, Fluka) and respiratory chain inhibitors oligomycin A (7.5 mg/ml, Sigma) and sodium azide (1.5 mM, Sigma) was performed for 30 or 60 min prior to treatment with H 2 O 2 . For inhibition of protein synthesis, cells were treated with 50 mg/ml or 200 mg/ml of cycloheximide (Sigma) for 30 min. Cell fixation was achieved by addition of formaldehyde (final concentration 1%) or EtOH (final concentration 70%) to exponentially growing yeasts and incubation in room temperature for 10 min or 60 min, respectively. Formaldehyde was quenched by addition of glycine to the final concentration of 0.4 M for 5 min. Following the removal of fixation agents, cells were exposed to H 2 O 2 for 200 min as described earlier.