Figure 1. eIF2α phosphorylation is a key factor in the chronological lifespan of S. pombe. (A) eIF2α phosphorylation during the transition from exponential to stationary growth phase. Wild type (WT) and eIF2α.S52A (S52A) cells growing in exponential phase (OD550 = 0.5-1) were collected at different time points, as indicated. eIF2α phosphorylation (eIF2α-P) and total amount of eIF2α were detected by western blot. (B) Growth curve of WT and eIF2α.S52A cells during exponential growth phase and the onset of stationary phase. Measurement of culture density (OD550) is represented in logarithmic scale against time. (C, D) Serial dilutions (1/5) of different S. pombe strains growing in YES medium at the exponential phase (Control) or five (C) or six (D) days after reaching stationary phase, as indicated, were plated onto YES-Agar plates and were incubated at 30° C for 2-3 days. Data information: (A–D) Representative results from at least three independent experiments.