Summary
This study reveals that the per2 clock gene plays tissue-specific roles in setting circadian phase, with internal organs showing a 6-hour phase delay in clock gene expression in per2 knockout zebrafish under light-dark cycles, while light-exposed superficial tissues are unaffected. These findings have implications for understanding how light intensity gradients within the body differentially regulate peripheral circadian clocks, informing the design of lighting interventions targeting specific physiological systems.
Key Findings
- per2 knockout zebrafish showed a 6-hour phase delay in clock1 and cry1a core clock gene expression specifically in internal organs (heart, liver, gut, muscle) but not in superficial tissues (brain, eyes, fin) under light-dark conditions.
- Explanted fin and heart tissue cultures from per2 KO fish maintained rhythmic clock gene expression equivalent to wild-type under LD conditions, demonstrating per2 is not essential for direct light entrainment of peripheral clocks.
- per2 KO larvae showed altered robustness and precision of rhythmic locomotor output in free-running conditions, but normal food anticipatory activity under time-restricted feeding, linking per2 function specifically to the light-entrainable clock.
- Pharmacological inhibition of TGF-β signaling generated a phase delay in per1b mRNA rhythms and reversibly disrupted clock-controlled rhythmic locomotor activity, revealing a functional interaction between TGF-β signaling and the circadian clock.
Categories
Sleep & Circadian Health: Investigates circadian clock input/output pathways, entrainment mechanisms, and phase regulation under light-dark cycles using zebrafish as a genetic model.
The Science of Light: Demonstrates tissue-specific, light-intensity-dependent roles of the per2 clock gene in peripheral clock entrainment, with direct implications for understanding photoentrainment mechanisms.
Author(s)
G Ruggiero
Publication Year
2019
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The Science of Light
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