Three types of genes affected by light entrainment.

<p>(A) The circadian expression of fast light-induced genes, slow light-induced genes, and dark-induced genes and representatives of each group (<i>per2</i>, <i>cry2a</i>, and <i>aanat1</i>) on the microarrays are shown. (B) The distinct kinetics of <i>per2</i>, <i>cry2a</i>, <i>aanat1</i>, and <i>clock</i> genes upon light or dark exposure in larval zebrafish fertilized and raised under either DD or LL conditions respectively for 20 hours starting at 5 dpf (5DD to LL and 5LL to DD). The larval zebrafish remained in the constant conditions (5DD to DD and 5LL to LL) were used as controls. The lowest log2-transformed expression level for each gene was normalized to zero. Two independent time-series experiments were conducted with error bars shown in the figure.