How feeding schedules affect activity and daily gene patterns in the brain and liver of zebrafish under different light and feeding setups

Zebrafish exhibit food-anticipatory activity when fed at scheduled times, indicating that feeding can synchronize their biological clocks.

• Feeding at fixed times resulted in food-anticipatory activity across all tested groups.
• Zebrafish under constant bright-light conditions displayed a free-running circadian rhythm with a period close to 24 hours after fasting.
• The brain's expression of the clock gene per1 maintained a daily rhythm under a light-dark cycle, peaking at the end of the dark phase irrespective of the feeding schedule.
• In constant bright-light conditions, the daily rhythm of per1 expression in the brain was lost regardless of the feeding schedule.
• Scheduled feeding during the mid-dark phase advanced the liver's per1 expression phase by 7 hours compared to feeding during the mid-light phase.
• Scheduled feeding also synchronized per1 expression rhythms in the liver under constant bright-light conditions.

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