: A Regulator of Multiple Tissue-Specific Circadian Functions.

The zebrafish represents a powerful model for exploring how light regulates the circadian clock due to the direct light sensitivity of its peripheral clocks, a property that is retained even in organ cultures as well as zebrafish-derived cell lines. Light-inducible expression of the clock gene has been predicted to play a vital function in relaying light information to the core circadian clock mechanism in many organisms, including zebrafish. To directly test the contribution of to circadian clock function in zebrafish, we have generated a loss-of-function gene mutation. Our results reveal a tissue-specific role for the gene in maintaining rhythmic expression of circadian clock genes, as well as clock-controlled genes, and an impact on the rhythmic behavior of intact zebrafish larvae. Furthermore, we demonstrate that disruption of the gene impacts on the circadian regulation of the cell cycle . Based on these results, we hypothesize that in addition to serving as a central element of the light input pathway to the circadian clock, acts as circadian regulator of tissue-specific physiological functions in zebrafish.