Flies expressing per^Scer\UAS.cKa under the control of Scer\GAL4^tim.PE in a Scer\GAL80^Pdf.PS background show rhythmic locomotor activity under constant light conditions, in contrast to wild-type flies, which are uniformly arrhythmic under these conditions.

The majority of flies expressing per^Scer\UAS.cKa under the control of Scer\GAL4^per.PK or Scer\GAL4^tim.PE synchronise to light:dark (LD) cycles in a locomotor-activity rhythm assay, although the proportion of entrained flies is slightly lower than that of control flies. The pattern of locomotor activity in LD conditions of flies expressing per^Scer\UAS.cKa under the control of Scer\GAL4^tim.PE at 29^oC is qualitatively abnormal; these flies do not show the activity increase that normally occurs before lights-off, instead there are high levels of locomotion just after lights-off. In addition, the flies stay relatively active throughout the night and do not show activity increases a few hours before lights-on. The increase in locomotion that normally occurs before lights-off under LD conditions is less prominent in flies expressing per^Scer\UAS.cKa under the control of Scer\GAL4^per.PK at 29^oC than in control flies. Under constant darkness conditions at 29^oC, a large proportion of flies expressing per^Scer\UAS.cKa under the control of Scer\GAL4^tim.PE become arrhythmic in a locomotor activity assay, in contrast to control flies, which are rhythmic. A slight reduction in rhythmicity under constant darkness conditions at 29^oC compared to control flies is seen in flies expressing per^Scer\UAS.cKa under the control of Scer\GAL4^per.PK. The circadian periodicity of these flies is indistinguishable from that of controls.