A NEW GENE ENCODING A PUTATIVE TRANSCRIPTION FACTOR REGULATED BY THE DROSOPHILA CIRCADIAN CLOCK

Circadian rhythms of locomotor activity and eclosion in Drosophila dep end upon the reciprocal autoregulation of the period (per) and timeles s (tim) genes. As part of this regulatory loop, per and tim mRNA level s oscillate in a circadian fashion. Other cycling transcripts may part icipate in this central pacemaker mechanism or represent outputs of th e clock. In this paper, we report the isolation of Crg-1, a new circad ianly regulated gene. Like per and tim transcript levels, Crg-1 transc ript levels oscillate with a 24 h period in light:dark (LD) conditions with a maximal abundance at the beginning of the night. These oscilla tions persist in complete darkness and depend upon per and tim protein s. The putative CRG-1 proteins show some sequence similarity with the DNA-binding domain of the HNF3/fork head family of transcription facto rs. In the adult head, in situ hybridization analysis reveals that per and Crg-1 have similar expression patterns in the eyes and optic lobe s.