Under dim (35-55 lux) constant light conditions, 88.9% of mutant flies show robust locomotor activity rhythmicity, with an average period length of 24.0 hours (depending on the lines used), whereas control animals are largely arrhythmic under these conditions.
cryOUT mutants subjected to light-dark (LD) (with twilight simulation) and temperature cycles, in phase, display tiny morning peaks and sharp evening peaks of activity. They are completely inactive in the dark phase. After a shift of the LD cycle, cryOUT flies seem to very slowly re-entrain to the LD cycle, with darkness exerting a strong negative masking effect on the activity so that the trajectory of the rhythm is disrupted during the dark phase. Mutant flies take longer to re-synchronize compared to wild-type flies and either seem to free-run (in LD) or to retrain to temperature cycles when in natural light-moonlight cycles (which reduces the negative masking effect of darkness). After a shift of daylight-moonlight (LM) cycles, the evening peak of cryOUT mutants remains at the same phase as before the shift (whereas wild-type follow the shift). cryOUT mutants are mainly entrained by temperature cycles and are neither free-running nor entrained by light-moonlight cycles.
Homozygous cryOUT mutants show short circadian free-running periods under blue light. After experimental exposure to a 300 microT magnetic field, the majority of the cryOUT mutants do not show any period changes, or if changes occur, the changes are significantly smaller than those in wild-type flies.
cryOUT mutant flies show anomalous rhythmic locomotor activity under constant light conditions (wild-type flies are arrhythmic under these conditions).