Stress-sensitivity of Δphx1 mutant and the inducibility of phx1 + gene by various stresses. (A) Stress-sensitivity of Δphx1 mutant. To examine sensitivity of the wild-type (JH43) and Δphx1 mutant to various oxidants and heat, exponentially growing cells in liquid EMM at 30°C were treated with 10 mM of H2O2, 20 mM of paraquat, 20 mM of diamide, or 2 mM menadione for 40 min each, or transferred to 42°C incubator for 30 min. Following stress treatment, equal number of cells were serially diluted, spotted onto EMM plates, and incubated at 30°C for 4 to 5 days. (B) Inducibility of phx1+ gene by various stresses. The wild-type (JH43) cells were grown to mid-exponential phase (OD600 of 0.5-1) in liquid EMM at 30°C, and treated with 10 mM hydrogen peroxide, 20 mM paraquat (PQ), 20 mM diamide (DA), or 2 mM menadione (MD) for 40 min each, or heat-shocked at 50°C for 30 min. RNA samples were analyzed for the level of phx1+ transcript in comparison with act1+, an internal control, by qRT-PCR. The average induction folds with standard deviations (error bars) from three independent experiments were presented.