Fig. 1

Fig. 1

Effect of light exposure in the expression of per2, cry1a, per3, and per1b on Z3 cells. (a) Z3 cells were entrained for three LD cycles of 12:12 h. After the third day of entrainment, cells were exposed to constant darkness (DDDD) and mRNA expression of the genes per2, cry1a, per3, and per1b were analyzed every 4 h for 48 h. The eJTK test detected circadian rhythmicity on per3 and per1b, with a p-value of 0.01. No rhythmicity was detected in per2 and cry1a in DDDD. (b) mRNA expression of the genes per2, cry1a, per3 and per1b after a 12-hour exposure of low-intensity light (~ 4.12 × 10¹⁸ photons/s/m²) with subsequent darkness (LDDD). Samples were taken every 4 h for 48 h. Transcript levels were measured against time zero. Yellow bar: light exposure. Grey bar: constant darkness. Means ± SD are shown. Three replicates per group, one experiment.