Figure 2 of
Chaurasia, Mol Vis 2006;
Figure 2. Temporal expression of negative modulators of the circadian clockwork system
Circadian profiles of Cry1 (A) and Per2 (B) transcripts in the photoreceptor-enriched retinal cell cultures collected at the indicated zeitgeber time (ZT) in light-dark (LD) and dark-dark (DD). Each data point represents clock gene transcripts normalized to Hprt mRNA, expressed relative to the lowest values in LD. ANOVA indicated significant differences (p<0.001) with high levels of both transcripts in the first half of the day in LD and DD; There were 6 cultures for each time. Acute light exposure at night induces Cry1 (C) and Per2 (D) mRNA expression. On day in vitro 9, cells were kept in constant darkness until ZT 18, when one group of cells was collected. Another group of cells remained in darkness for an additional 2 h (solid symbol), while a third group of cells was exposed to light for 2 h prior to cell harvesting (open symbol). Exposure to light significantly increased Cry1 and Per2 transcript levels (p<0.001; n=5-6 culture dishes per group).