RHYTHMIC EXPRESSION OF TIMELESS - A BASIS FOR PROMOTING CIRCADIAN CYCLES IN PERIOD GENE AUTOREGULATION

The clock gene timeless (tim) is required for circadian rhythmicity in Drosophila. The accumulation of tim RNA followed a circadian rhythm, and the phase and period of the tim RNA rhythm were indistinguishable from those that have been reported for per. The tim RNA oscillations w ere found to be dependent on the presence of PER and TIM proteins, whi ch demonstrates feedback control of tim by a mechanism previously show n to regulate per expression. The cyclic expression of tim appears to dictate the timing of PER protein accumulation and nuclear localizatio n, suggesting that tim promotes circadian rhythms of per and tim trans cription by restricting per RNA and PER protein accumulation to separa te times of day.