A Fly's Eye View of Circadian Entrainment

Light directly influences the circadian clock in Drosophila through the blue-light photoreceptor cryptochrome (CRY).

• The circadian clock in Drosophila is driven by a feedback loop of the genes period (per) and timeless (tim).
• CRY activation leads to the rapid degradation of TIM, contributing to daily resetting of the clock at dawn.
• Light serves as the primary external cue for synchronizing the circadian rhythm with the day-night cycle.
• In the absence of cryptochrome, the clock can still respond to light through the visual system, though the mechanisms are not fully understood.
• Temperature is another factor that can influence the circadian clock, with unclear underlying mechanisms.

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