Figure 7. Hormetic effect of H2O2 on replicative longevity.
(A) Sketch of the microfluidic device used for replicative aging experiments. (B) Sequence of overlaid phase-contrast and fluorescence images (Htb2-sfGFP, used as a nuclear marker to score cell division) of mother cells growing in individual cavities. Numbers indicate the timing (white) and number of cell divisions (yellow) for the mother cell at the tip of the cavity. (C) Survival curves for wild-type cells growing in media containing H2O2 at the indicated concentrations. (D) RLS as a function of H2O2 concentration. Box represents median and 95% CI. U test. Red line shows the median RLS for 0 mM H2O2. (E) Survival curves of Δyap1 and Δtsa1 mutants in the presence or absence of 10 μM H2O2. (F) Frequency of specific fluorescence foci (Ddc2-GFP, Hsp104-GFP) as a function of H2O2 concentration. Error bars are 95% CI. (G) (Top to bottom) Recapitulation of measurements of RLS (blue), Tsa1-GFP steady-state upregulation (green), and frequency of damage (DDC2 foci in brown, Hsp104 foci in purple). Bottom: Conceptual sketch showing the contributions of protective (black) and deleterious (red) effects of H2O2 on RLS.