Genetic Analysis of Ectopic Circadian Clock Induction in Drosophila

Ectopic expression of the gene Clk in Drosophila induces widespread molecular oscillations throughout the brain.

• Clk activates various clock components, many of which regulate Clk expression or activity.
• Ectopic Clk is the only clock component found to induce new circadian rhythms, while other components fail to do so.
• Oscillations induced by Clk can occur even in differentiated cells when expression is restricted to adults.
• Discontinuation of Clk transgene expression leads to the loss of molecular oscillations, indicating its continuous activity is necessary.
• Clk-mediated induction of the clock component PERIOD (PER) can occur without synchronized cycling, suggesting additional factors may be required for coherent rhythms.
• Ectopic clock induction is not observed in mutants lacking Clk's partner protein cyc, and noncycling PER occurs in a specific mutant background.

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