Rat retina shows strong daily rhythms of clock and related genes in lab culture

Rhythmic expression was found for all studied clock genes and clock downstream targets in retinal explants maintained in darkness.

• All examined clock genes exhibited a cyclical expression pattern.
• Clock output genes such as c-fos and Aanat also showed rhythmic expression.
• The expression cycles of clock and output genes occurred with similar timing and peaked during subjective night.
• Bioluminescence monitoring confirmed the rhythm of Per1 expression in the retinal explants.
• The findings suggest that the retina operates as a self-sustained biological clock.

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