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Light-induced phase shifts in mice lacking mPER1 or mPER2
1Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Journal of Biological Rhythms
|April 16, 2003
Summary
Mammalian Period (mPer) genes mPer1 and mPer2 are involved in circadian rhythms. Light-induced phase shifts were observed in mPer1 and mPer2 mutant mice, challenging their proposed nonoverlapping roles.
Area of Science:
- Chronobiology
- Molecular Biology
- Genetics
Background:
- Mammals possess three Period (mPer) gene homologs: mPer1, mPer2, and mPer3.
- mPer1 and mPer2 are crucial for circadian rhythm maintenance, while mPer3 is not.
- mPER1 and mPER2 are implicated in transmitting light signals to the circadian clock.
Purpose of the Study:
- To investigate the roles of mPer1 and mPer2 in mediating light's effects on the mammalian circadian clock.
- To examine the phase-shifting responses to light in mPer1-deficient and mPer2-deficient mice.
Main Methods:
- Utilized T cycle paradigms with daily 1-hour light pulses at varying intervals (T=24h for delays, T=22h for advances).
- Assessed light-induced phase delays and advances in mPer1- and mPer2-deficient mice.
- Compared responses between mutant mice and wild-type controls (implied).
Main Results:
- Despite some loss of rhythmicity in mutant mice, both phase delays and advances were observed in mPer1- and mPer2-deficient individuals.
- Light-induced phase shifts occurred in the absence of functional mPer1 or mPer2 genes.
Conclusions:
- The findings contradict the hypothesis that mPER1 and mPER2 have necessary and distinct roles in mediating light's effects on the circadian clock.
- mPer1 and mPer2 may have overlapping or redundant functions in photic entrainment of the circadian system.