Figure 4.

Daily expression levels of clock genes in zebrafish larvae. Quantitative polymerase chain reaction (qPCR) analysis of clock and light-regulated clock gene expression at 5–6 dpf (A,C,E,G,I) and 12 dpf (B,D,F,H,J) in zebrafish larvae exposed to LD cycles. For all panels, each point represents the mean ± SEM (n = 4). On the y-axes are plotted relative expression levels (100% is the maximum level detected for each gene in all dpf), while on the x-axes time is expressed as zeitgeber time (ZT, where ZT0 represents lights on). White and black bars represent light and dark periods, respectively. gr^+/+ = solid line; gr^−/− = dotted line.