Figure 6.

Interference with cyclin D function on Night 1 inhibits S- and G₂/M-phase progression over the following day and Night 2. A, Administration of PD 0332991, a CDK4/6 inhibitor, at ZT22 of Night 1 leads to a reduction in the expression of cyclins A2 and B2 on Night 2 (ZT19′ and ZT23′, combined). B, Reduction in the number of BrdU+ cells during the day (ZT11′) and Night 2 (ZT15′), after a 4 h exposure to BrdU (immersion). n = 5–6 fish per time point; mean ± SEM; *p < 0.05 relative to control. ZT0 is lights-on time.