Flies show delayed activity rhythms at cold temperatures and short photoperiods. Flies lack anticipatory rises in evening activity under 6:18LD and display significant delays in peak of evening activity. Daily activity rhythms are preferentially delayed under the shorter photoperiod. In 12:12 LD at 18oC: peak activity is at 11.4+/-0.2hr, period = 24.2+/-0.2hr and rhythmicity = 40.5%. In 6:18 LD at 18oC: peak activity is at 6.0+/-0.1hr, period = 23.8+/-0.1hr and rhythmicity = 56.5%. In 12:12 LD at 29oC: peak activity is at 12.8+/-0.1hr, period = 23.7+/-0.1hr and rhythmicity = 66.7%. In 6:18 LD at 29oC: peak activity is at 7.1+/-0.2hr, period = 24.2+/-0.1hr and rhythmicity = 64.2%.
Rescues locomotor activity rhythms in per01 flies.