Fig. 3

Circadian rhythm of clock gene expression monitored using luciferase reporters. a Bioluminescence rhythms of cultured explants (300-μm-thick slices of the SCN, lung, and liver) and an eye from transgenic mice carrying a Bmal1 promoter-driven luciferase reporter (Bmal1-luc) (see Ref. [115]). Data was monitored by a PMT and expressed in relative light units (RLU). Horizontal gray and black bars on the abscissa indicate the light–dark (LD) cycles to which animals were entrained. b Bmal1-luc rhythm of a single Rat-1 fibroblast cell before and during dexamethasone treatment. c In vivo recording of bioluminescence using fiber optics situated above the SCN (gray line). Behavioral activity (black histogram) was monitored simultaneously from a freely moving mouse carrying a Per1-luc reporter. Horizontal gray and black bars on the abscissa indicate subjective light and dark phases, respectively. Bioluminescence data was smoothed using the 4-h moving average method [72]