Energetics of cold adaptation.
A and B, average oxygen consumption over 24-h periods at each temperature indicated during the cold adaptation. A, not normalized to body weight; B, normalized to body weight. C and D, oxygen consumption over a 24-h period at 4 °C. C, not normalized to body weight; D, normalized to body weight. * = p < 0.05, ** = p < 0.01, *** = p < 0.001. E, daily caloric intake per mouse at 4 °C. *** = WT versus DKO, p < 0.001; SLN-KO versus DKO, p < 0.05; UCP1-KO versus DKO, p < 0.01. F, change in body weight (in grams) from the start of the cold adaptation period to the end. * = WT versus DKO, SLN-KO versus DKO, UCP1-KO versus DKO, p < 0.05. Data are expressed as means ± S.E.