Figure 4. Increase in exogenous H2S does not affect cellular lifespan. Lifespan after addition of 50 μM sodium hydrosulfide (NaHS) at culture starting points (orange line) in wild-type, met3Δ, and met5Δ strains under regular (a to c) and MR (d to f) conditions. The graph indicates mean ± SEM. The gray dotted line indicates CLS without NaHS for each strain shown in Fig. 3. Statistical p-value between median CLS before and after NaHS addition was calculated using two-tailed Student’s t-test. The hydrogen sulfide levels measured using lead acetate paper is shown in the corner of the graph (original images are provided in Fig. S7).