Fig. 4.

Skeletal muscle core molecular clock genes are not aligned to behavioral rhythm upon circadian misalignment. mRNA expression levels of the core molecular clock genes BMAL1 (A), CLOCK (B), PER2 (C), and CRY1 (D) in skeletal muscle measured by RT-QPCR. Data are normalized to the geometric mean of three housekeeping genes and presented as mean ± SEM. *P < 0.05 comparing 7 AM and 7 PM in control and misalignment condition. #P < 0.05 comparing behavioral mornings in control vs. circadian misalignment condition (overnight fasted state before the clamp). Because only two time points per arm were investigated, the lack of difference in mRNA expression levels between 7 AM and 7 PM does not provide evidence that the measured parameter lacks 24 h rhythmicity.