Reduced cell rhythms in after-hours mutant mice are linked to stronger resetting of their internal clocks

The Afh mutation in mice is associated with reduced amplitude and altered rhythms of the core clock protein Cryptochrome.

• The Afh mutation slows degradation of Cryptochrome, lengthening the circadian period in the brain's suprachiasmatic nuclei.
• Daily rhythms of metabolism and feeding behaviors are altered in Afh mutant mice.
• PERIOD2::LUCIFERASE rhythms in the mediobasal hypothalamic nuclei also show changes, with a trend toward longer periods and decreased amplitude.
• Imaging of single cells indicates that the reduction in tissue oscillator amplitude is due to decreased single-cell amplitude, not desynchrony.
• Afh mutant mice demonstrate increased susceptibility to phase-shifting stimuli, with light causing high-amplitude Type 0 resetting.

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