Daily patterns of internal clock genes and feeding behavior during larval growth in gilthead seabream

Alterations in photoperiod significantly affect the expression of clock genes in gilthead seabream larvae.

• Under a regular light-dark cycle (12L:12D), larvae exhibited synchronized feeding and clock gene expression patterns.
• In continuous light (24L:0D), larvae maintained rhythmic patterns, but the timing of peaks varied with age.
• At 60 days post-hatch, clock gene expression and feeding rhythms in continuous light were similar to those in the light-dark cycle.
• The expression levels of the genes bmal1 and cry1 were considerably lower in continuous light compared to the light-dark cycle.
• The two-phases photoperiod (LL + LD) indicated age-dependent responses, with younger larvae resembling continuous light patterns and older ones resembling light-dark patterns.
• These findings suggest that internal mechanisms influence rhythmic physiological responses in developing fish larvae under varying light conditions.

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