Two body clocks control movement rhythms and respond differently to light in fruit flies with the cryb mutation

Cryb mutant flies exhibit free-running rhythms with two distinct components in constant light conditions.

• Wild-type Drosophila melanogaster became arrhythmic when exposed to constant light.
• Cryb mutant flies displayed two separate circadian oscillators with varying light responsiveness.
• The dissociation of rhythms in cryb mutants was influenced by light intensity, with more flies showing both oscillations at higher intensities.
• External photoreceptors, including compound eyes and ocelli, likely mediate the rhythm dissociation.
• Different populations of neurons exhibited distinct patterns of PERIOD expression, suggesting two separate mechanisms driving locomotor rhythms.

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