Fig. 3.

Nkx2.1iCre/+;Ngn3^flox/flox mutant mice exhibit decreased energy expenditure at 17 weeks of age compared with controls. (A,B) Oxygen consumption in male and female mice. There is a trend for decreased oxygen consumption in mutant male mice compared with control mice particularly in the night-time dark phase (A), whereas, in female mutant mice, oxygen consumption if significantly reduced compared with controls (B). (C,D) CO₂ production is significantly reduced in both male (C) and female (D) mutant mice compared with control littermates. (E,F) Respiratory exchange ration (RER) is significantly lower in male mutant mice compared with controls (E); no difference is observed in females (F). (G,H) Movement, measured by total movement (G) and ambulatory activity (H), is significantly reduced in mutant mice during the dark phase but not during the light phase. (I,J) There is a reduction in heat production in mutant mice. Male mice show a trend of reduced heat production compared with controls, particularly in the dark phase (I), whereas heat production is consistently reduced in female mutant mice (J). *P<0.05, **P<0.01, ***P<0.005.