Mouse Period1 helps adjust the body clock to light and dark cycles by controlling Period2 protein

Prolongation of the lighting period by 4-16 hours induces a larger behavioral phase shift in mPer1-deficient (mPer1-/-) mice.

• mPer1-deficient mice demonstrate a slower decay of mPER2 protein (approximately 4 hours) compared to wild-type mice.
• This slower decay is associated with a larger delay in behavioral rhythm phase shifts in mPer1-/- mice.
• mPer1-/- mice are unable to adapt to long light/dark cycles under conditions with dim light or extended skeleton photoperiods.
• These findings suggest a role for mPer1 in helping nocturnal mice adjust their circadian clock to significant seasonal variations in light.

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