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  • The EMBO Journal (2003) 22, 3367 - 3375
  • doi:10.1093/emboj/cdg318

A recessive mutant of Drosophila Clock reveals a role in circadian rhythm amplitude

Ravi Allada1,2, Sebastian Kadener1, Namrata Nandakumar1 and Michael Rosbash1

  1. Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454 USA
  2. Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA

Correspondence to:

Michael Rosbash, E-mail: rosbash@brandeis.edu

Received 5 February 2003; Accepted 12 May 2003; Revised 8 April 2003

The transcription factor Clock (Clk) plays a critical role in animal circadian rhythms. Genetic studies defining its function have relied on two dominant negative alleles, one in Drosophila and one in mice. Here we describe a novel recessive allele of Drosophila Clock, Clkar. Homozygous Clkar flies are viable and behaviorally arrhythmic. The Clkar phenotype is caused by a splice site mutation that severely disrupts splicing and reduces Clk activity. Despite the behavioral arrhythmicity, molecular oscillations are still detectable in Clkar flies. Transcription analysis indicates potent effects of Clkar on levels and amplitude of transcriptional oscillations. Taken together with other data, we propose that Clk makes a major contribution to the strength and amplitude of circadian rhythms.

  • Keywords:

    • amplitude,
    • circadian rhythms,
    • Clock,
    • mutant allele,
    • transcription