Microarray Analysis and Organization of Circadian Gene Expression in Drosophila

A total of 134 cycling genes were identified in Drosophila melanogaster that are involved in various biological processes.

• Circadian gene expression in Drosophila is governed by the CLOCK (CLK) transcription factor.
• All oscillating gene expression is under the control of clk, indicating no clk-independent circadian systems exist in these flies.
• Many clock-regulated genes are located in clusters and appear to be regulated together.
• A larger number of genes are affected in Clk mutant flies, suggesting clk's influence extends to other genetic networks.
• Only a small number of direct target genes were identified, implying that most of the circadian gene network is regulated indirectly by clk.

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