Oxidative stress resistance and chronological lifespan

Oxidative stress resistance was determined in yeast cells grown to exponential phase (OD_600nm = 0.6) and treated with 0.5 mM H₂O₂ (Merck, Darmstadt, Germany) for 30 min. Chronological lifespan was assayed as previously described.³⁹ Briefly, overnight cultures were diluted to OD_600nm = 0.5 and grown for 48h (stationary phase; considered t0 in the lifespan assay) and kept in culture media at 26°C for the indicated times. Cell viability was determined by standard dilution plate counts on YPD medium containing 1.5 % agar. Colonies were counted after growth at 26°C for 3 d. Viability was expressed as the percentage of the colony-forming units.