Abstract
We report the identification, characterization, and cloning of a novel
Drosophila circadian rhythm gene,
dClock. The mutant, initially called
Jrk, manifests dominant effects: heterozygous flies have a period alteration and half are arrhythmic, while homozygous flies are uniformly arrhythmic. Furthermore, these flies express low levels of the two clock proteins, PERIOD (PER) and TIMELESS (TIM), due to low
per and
tim transcription. Mapping and cloning of the
Jrk gene indicates that it encodes the
Drosophila homolog of mouse
Clock. The mutant phenotype results from a premature stop codon that eliminates much of the putative activation domain of this bHLH-PAS transcription factor, thus explaining the dominant features of
Jrk. The remarkable sequence conservation strongly supports common clock components present in the common ancestor of
Drosophila and mammals.