Figure 2

Chronological lifespan extension in yeast by metabolic introduction of heavy hydrogen isotopes deuterium through heavy water (D₂O). See also Supplementary Figure S2. (a) Chronological survival curves for yeast (S. cerevisiae) strains DBY746, BY4741 and BY4743, respectively (n=3). Chronological aging assays were performed in fortified SDC medium as described previously (see Materials and Methods) for several common laboratory strains. Fresh culture was used to inoculate SDC medium containing different amounts of D₂O (v/v). Colony formation was determined from day 3 and every 2 days thereafter until the survival rate dropped below 10% (representative images in Supplementary Figure S2A). At least three independent experiments were performed, and one is shown here. Top right panel shows mean lifespans (estimated by Kaplan–Meier survival analysis, shown inside each bar) of DBY746 strain in media containing D₂O. P values (log-rank test after Bonferroni correction) of pair-wise comparisons are indicated above the bars (*, <0.05; ****, <1E-4). Error bars=s.e.m. (b) CLS assays of three yeast mutants (BY4741 background) treated with 50% D₂O, each with a deletion of a known aging regulator gene in yeast (n=3). Two independent experiments were performed, and one is shown here. The mean lifespans and P values are estimated by log-rank test and indicated on each panel. The experiments were from the same culture presented in a. Error bars=s.e.m. (c) Deuterium introduced through carbon sources (glucose) failed to extend CLS in yeast to a significant extent. The total glucose concentration is 2% (w/v) in all conditions. D₇-glucose contains deuterium at all seven of nonexchangeable hydrogen positions (structure shown on right). The mean lifespans and P values (log-rank test, versus 0% D₇-glucose) are indicated with the same color of survival curves. NS, not significant. Error bars=s.e.m.