Figure 5. Sir2p and rapamycin extend replicative lifespan.
(A) Replicative lifespans and (B) hazard rates of strains normalized to the mean RLS and hazard rate of wild-type (h- 972) strain. Error bars: 95% C.I. on an exponential decay fit to the experimental survival curve. (C) Distribution of normalized doubling time in the five generations preceding death for Sir2p overexpression cells and (D) wild-type cells treated with 100 nM rapamycin. (E) Distribution of normalized length at division in the five generations preceding death for Sir2p overexpression cells and (F) wild-type cells treated with 100 nM rapamycin. Black bars show the median value. Sequential generations were compared using the Kolmogorov-Smirnov test (* for p<0.05, ** for p<0.01; n > 144 cells for all conditions).
Figure 5—figure supplement 1. Sir2p expression levels.
(A) sir2 mRNA transcript levels as measured by qPCR. The sir2Δ strain was included as a negative control. Error bars: normalized SEM of at least three replicates. (B) Sir2p protein levels as detected by an anti-Sir2p antibody. Actin is included as loading control. Sir2p-eGFP migrates slower than endogenous Sir2p. (C) Single cell fluorescence imaging confirms that Sir2p-eGFP is expressed and localizes to the nucleus. Scale bar: 20 µm.
Figure 5—figure supplement 2. The effect of Sir2p and rapamycin on the RLS of fission yeast.
(A) The replicative half-life is indicated in parenthesis. A lower bound is reported for the long-lived Sir2p overexpression strain. Red lines represent an exponential decay fit to the curve. (B) Hazard functions of strains shown in (A). The constant hazard rates illustrate that none of the WT strains are aging.