Effects of constant light on circadian rhythmicity in mice lacking functional cry genes: dissimilar from per mutants

Spoelstra, Kamiel; Daan, Serge

doi:10.1007/s00359-007-0301-3

Cited by 20 publications

(28 citation statements)

References 29 publications

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“…4C, E). These data are consistent with previous studies that examined different lines of Per1 −/− and Per2 −/− mice in LL (Steinlechner et al, 2002; Spoelstra and Daan, 2008). The amplitude (Q p ; F (3,27) = 0.88, p = 0.47) (Fig.…”

Section: Resultssupporting

confidence: 93%

Photic Entrainment ofPeriodMutant Mice is Predicted from Their Phase Response Curves

Pendergast¹,

Friday²,

Yamazaki³

2010

J. Neurosci.

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A fundamental property of circadian clocks is that they entrain to environmental cues. The circadian genes, Period1 and Period2, are involved in entrainment of the mammalian circadian system. To investigate the roles of the Period genes in photic entrainment, we constructed phase response curves (PRC) to light pulses for C57BL/6J wild-type, Per1 Ϫ/Ϫ , Per2, and Per3 Ϫ/Ϫ mice and tested whether the PRCs accurately predict entrainment to non-24 light-dark cycles (T-cycles) and constant light (LL). The PRCs of wild-type and Per3 Ϫ/Ϫ mice are similar in shape and amplitude and have relatively large delay zones and small advance zones, resulting in successful entrainment to 26 h T-cycles (T26), but not T21, with similar phase angles. Per1 Ϫ/Ϫ mice have a high-amplitude PRC, resulting in entrainment to a broad range of T-cycles. Per2 Ϫ/Ϫ mice also entrain to a wide range of T-cycles because the advance portion of their PRC is larger than wild types. Period aftereffects following entrainment to T-cycles were similar among all genotypes. We found that the ratio of the advance portion to the delay portion of the PRC accurately predicts the lengthening of the period of the activity rhythm in LL. Wild-type, Per1Ϫ/Ϫ , and Per3 Ϫ/Ϫ mice had larger delay zones than advance zones and lengthened (Ͼ24 h) periods in LL, whereas Per2 Ϫ/Ϫ mice had delay and advance zones that were equal in size and no period lengthening in LL. Together, these results demonstrate that PRCs are powerful tools for predicting and understanding photic entrainment of circadian mutant mice.

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Section: Resultssupporting

confidence: 93%

Photic Entrainment ofPeriodMutant Mice is Predicted from Their Phase Response Curves

Pendergast¹,

Friday²,

Yamazaki³

2010

J. Neurosci.

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“…Consistent with these observations is the finding that light-dependent phase advances or delays are impaired in mice mutant in the Per1 or Per2 genes, respectively (49). However, it appears that behavioral responses to light are strongly dependent on the light history that an organism experienced (50,51).…”

Section: The Suprachiasmatic Nuclei: a Relay To Synchronize Physiologmentioning

confidence: 69%

The Mammalian Circadian Timing System: Organization and Coordination of Central and Peripheral Clocks

Dibner¹,

Schibler

Albrecht

2010

Annu. Rev. Physiol.

2,055

1,771

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Most physiology and behavior of mammalian organisms follow daily oscillations. These rhythmic processes are governed by environmental cues (e.g., fluctuations in light intensity and temperature), an internal circadian timing system, and the interaction between this timekeeping system and environmental signals. In mammals, the circadian timekeeping system has a complex architecture, composed of a central pacemaker in the brain's suprachiasmatic nuclei (SCN) and subsidiary clocks in nearly every body cell. The central clock is synchronized to geophysical time mainly via photic cues perceived by the retina and transmitted by electrical signals to SCN neurons. In turn, the SCN influences circadian physiology and behavior via neuronal and humoral cues and via the synchronization of local oscillators that are operative in the cells of most organs and tissues. Thus, some of the SCN output pathways serve as input pathways for peripheral tissues. Here we discuss knowledge acquired during the past few years on the complex structure and function of the mammalian circadian timing system.

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“…It has been proposed that M and E oscillators might represent transcription-translation loops of clock genes, with Per1 a part of M and Per2 a part of E (33). Evidence both for and against this proposition has been gathered using animals genetically deficient in Per and Cry genes (6,(34)(35)(36)(37), although Per1-and Per2-deficient mice can show intact phase-shifting responses. Though our results do link Per1 with dawn and Per2 with dusk, they intimate that M and E oscillator components are not only affected by different genes but also may be entrained by distinct molecular mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Distinct patterns of Period gene expression in the suprachiasmatic nucleus underlie circadian clock photoentrainment by advances or delays

Schwartz¹,

Tavakoli-Nezhad²,

Lambert

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The circadian clock in the mammalian hypothalamic suprachiasmatic nucleus (SCN) is entrained by the ambient light/dark cycle, which differentially acts to cause the clock to advance or delay. Light-induced changes in the rhythmic expression of SCN clock genes are believed to be a critical step in this process, but how the two entrainment modalities-advances vs. delays-engage the molecular clockwork remains incompletely understood. We investigated molecular substrates of photic entrainment of the clock in the SCN by stably entraining hamsters to T cycles (non-24-h light/ dark cycles) consisting of a single 1-h light pulse repeated as either a short (23.33-h) or a long (24.67-h) cycle; under these conditions, the light pulse of the short cycle acts as "dawn," whereas that of the long cycle acts as "dusk." Analyses of the expression of the photoinducible and rhythmic clock genes Period 1 and 2 (Per1 and Per2) in the SCN revealed fundamental differences under these two entrainment modes. Light at dawn advanced the clock, advancing the onset of the Per1 mRNA rhythm and acutely increasing mRNA transcription, whereas light at dusk delayed the clock, delaying the offset of the Per2 mRNA rhythm and tonically increasing mRNA stability. The results suggest that the underlying molecular mechanisms of circadian entrainment differ with morning (advancing) or evening (delaying) light exposure, and such differences may reflect how entrainment takes place in nocturnal animals under natural conditions. circadian synchronization | circadian clock resetting | light entrainment A fundamental feature of the circadian clock that regulates daily behavioral and physiological rhythmicity is its entrainment to the environmental cycle of light and darkness. By matching the clock's endogenous ("free-running") period to that of the ambient day/night cycle, entrainment ensures that the phase relationship between clock and external day remains stable over time, thereby synchronizing body rhythms to local time. Light is the clock's preeminent entraining cue (Zeitgeber), and the clock responds to light by changing its angular velocity and shifting its phase. To match its oscillation to that of the Zeitgeber, the clock can increase its velocity and advance its phase if the clock's freerunning period is too long, or it can decrease its velocity and delay its phase if its free-running period is too short (1, 2).In mammals, the master circadian clock is located in the suprachiasmatic nucleus (SCN) in the anterior hypothalamus (3). The SCN is composed of multiple, coupled single-cell circadian oscillators (4), and analyses of induced and spontaneous mutations, gene sequence homologies, and protein-protein interactions have identified candidate regulatory molecules and biochemical processes that are likely to constitute the basic intracellular oscillatory mechanism (5). Genes at the core of the clock function within autoregulatory feedback loops, with proteins rhythmically suppressing the transcription of their own mRNAs. When the basic helix-loop-hel...

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Effects of constant light on circadian rhythmicity in mice lacking functional cry genes: dissimilar from per mutants

Cited by 20 publications

References 29 publications

Photic Entrainment ofPeriodMutant Mice is Predicted from Their Phase Response Curves

Photic Entrainment ofPeriodMutant Mice is Predicted from Their Phase Response Curves

The Mammalian Circadian Timing System: Organization and Coordination of Central and Peripheral Clocks

Distinct patterns of Period gene expression in the suprachiasmatic nucleus underlie circadian clock photoentrainment by advances or delays

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