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Updated: Jul 31, 2026

In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters
Published on: July 4, 2018
A cholinergic receptor 12-hour interval-timer displaying "circa" periodicities
Abstract:
The finding of brief pulses of receptor escape from atropine blocking of acetylcholine paralleling moonset and moonset-plus-12-hr led to a search for similar pulses paralleling sunset. Pulses occurring in the hour before sunset as well as in the hour before sunset-plus-12-hr were found. The pulses of receptor escape associated with sunset and sunset-plus-12-hr were in the opposite direction from those associated with moonset and moonset-plus-12-hr. The direction of receptor escape in all cases reversed with the winter solstice. These findings appear to provide evidence for an endogenous 12-hr interval-timer responding to external 24- and 24.8-hr oscillating systems which interact to yield a family of frequencies including those designated "circa".
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