FIGURE 6.

Per2 knockout alters the rhythmic mRNA expression of regulators of key physiological hepatic processes in the adult zebrafish liver. qRT-PCR analysis of expression levels of four CCGs (A) impdh2, (B) hnf1a, (C) cyp1a, and (D) ppargc1b in WT and per2 KO liver. Sets of 4 WT and per2 KO fishes (each set containing two males and two females) were maintained under LD cycle (14 h light-10 h dark) conditions, livers were dissected and pooled for RNA extraction at 6-h intervals during a sampling window of 24 h. Mean mRNA relative expression (n = 2–3) ± SD is plotted on the y-axis; zeitgeber time (ZT) is plotted on the x-axis. Zeitgeber times are indicated for each sample. ZT0 corresponds to lights-on, ZT14 to lights-off. A change in rhythm was observed for impdh2, hnf1a, cyp1a and ppargc1b, as determined by a significant ANOVA Genotype × Time interaction effect for all genes (p < 0.01, see Table 1). Furthermore, hnf1a exhibited a 12 h phase delay, and ppargc1b exhibited a 6 h phase delay. Asterisks represent levels of significance in comparing the two genotypes at each time point individually, corrected by Sidak’s method (***p < 0.001, **p < 0.01, *p < 0.05).