FIG. 3.

Circadian regulation of dClock mRNA cycling. (A) Levels of dClock mRNA in wild-type flies during the last 12-h LD cycle and the first 2 days in constant dark conditions. Peak levels of dClock mRNA at ZT3 were set to 100. Time refers to hours since last dark-to-light transition at ZT0. (B) PER and TIM are required for high-level expression of dClock. Levels of dClock mRNA in wild-type CS, per⁰¹, and tim⁰ flies during 12-h LD. Peak levels of dClock mRNA in wild-type flies was set to 100. Relative RNA levels refers to ratios of dClock to RP49 RNA. Closed bar, darkness; open bar, light; striped bar, subjective day. Each experiment was done at least three times with similar results, and representative examples are shown.