Pnc1 levels and activity are elevated in response to calorie restriction and low-intensity stress. a, Western analysis of Pnc1–GFP under conditions of glucose restriction. b, Pnc1–GFP in wild-type or cdc25-10 cells. c, Detection of Pnc1–GFP in cells subjected to mild stress as indicated (a.a., amino acid). d, Measurement of nicotinamide deamination by Pnc1. Activity (nmol ammonia min−1 per mg protein) from three experiments (means ± s.d): no treatment (2% glucose), 0.9 ± 0.26; calorie restriction (CR; 0.1% glucose), 4.38 ± 0.43; heat stress (37 °C), 3.28 ± 0.32; sorbitol (1 M), 3.75 ± 0.65.