Calorie restriction and heat stress extend lifespan in a PNC1-dependent manner. a, Pnc1 converts nicotinamide to nicotinic acid. b, In S. cerevisiae, NAD+ is synthesized de novo from tryptophan via Bna1–6 or recycled from nicotinamide. c, Average lifespan on 2.0% (w/v) glucose: wild type, 21.6 generations; pnc1Δ, 19.1; sir2Δ, 14.2. Average lifespan on 0.5% glucose: wild type, 32.7 generations; pnc1D, 18.1; sir2Δ, 14.7. d, At 30 °C, average lifespans: wild type, 19.4 generations; pnc1Δ, 18.5; sir2Δ, 12.0. At 37 °C, average lifespans: wild type, 23.4 generations; pnc1Δ, 17.5; sir2Δ, 10.6. e, Average lifespans on 2.0% glucose at 30 °C: wild type, 19.7 generations; 5×PNC1, 36.1; sir2Δ, 14.2; 5×PNC1
sir2Δ, 15.1; pnc1Δ
sir2Δ, 14.4.