Figure 2.

Wheel-running activity affects the phase of the liver clock. Male heterozygous PER2::LUC mice were single-housed in cages with either locked (open squares) or freely rotating (filled circles) running wheels. Mice were fed chow (gray symbols) or HFD (black symbols) for 1 week. The mean (±SD) phases were determined from the peaks of PER2::LUC expression during the interval between 12 and 36 h in culture and were plotted relative to the time of last lights on where 24 h is lights on and 36 h is lights off (white and black bar at top). The sample size is shown (number of rhythmic tissues/number of tissues tested). Locked wheel data is taken from Pendergast et al. (2013). There were main effects of wheel on the phases of the lung [F_{(1, 22)} = 9.22, p = 0.006], liver [F_{(1, 20)} = 30.72, p < 0.001], and spleen [F_{(1, 21)} = 15.29, p < 0.001] and main effects of diet on the phases of the liver (F = 71.25, p < 0.001) and spleen (F = 13.14, p = 0.002). There was no effect of an interaction between wheel and diet on the phase of any tissues.