Die Tagesperiodik licht- und dunkelaktiver Tiere

Aschoff, Jürgen

doi:10.5962/bhl.part.75618

Cited by 86 publications

(29 citation statements)

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“…It further tends to lengthen circadian rhythms in mammals. The lengthening of circadian period with increasing levels of constant illumination was originally considered to be speciWc for night-active animals (AschoV 1960;1964). On the basis of accumulating mammalian data AschoV (1979) later changed this rule into the generalization that all mammals, diurnal as well as nocturnal, lengthen the circadian period ( ) with increasing intensity of illumination.…”

Section: Introductionmentioning

confidence: 99%

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

Spoelstra

Daan

2007

J Comp Physiol A

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Citation for published version (APA): Spoelstra, K., & Daan, S. (2008). Effects of constant light on circadian rhythmicity in mice lacking functional cry genes: dissimilar from per mutants. Journal of comparative physiology a-Neuroethology sensory neural and behavioral physiology, 194(3), 235-242. DOI: 10.1007/s00359-007-0301-3 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract Mutations in each of the genes mPer1, mPer2, mCry1 and mCry2 separately cause deviations from the wild type circadian system. DiVerences between these mutant strains have inspired the hypothesis that the duality of circadian genes (two mPer and two mCry genes involved) is related to the existence of two components in the circadian oscillator (Daan et al., J Biol Rhythms 16:105-116, 2001). We tested the predictions from this theory that the circadian period ( ) lengthens under constant illumination (LL) in mCry1 and mPer1 mutant mice, while it shortens in mCry2 and mPer2 mutants. mCry1 ¡/¡ and mCry2 ¡/¡ knockout mice both consistently increased with increasing light intensity, as did wild type mice. With increasing illumination, rhythmicity is reduced in mCry1, mCry2 and mPer1, but not in mPer2 deWcient mice. Results for mPer mutant mice are in agreement with data reported on these strains earlier by Steinlechner et al. (J Biol Rhythms 17:202-209, 2002), and also with the predictions from the model. The increase in cycle length of the circadian system by light in the mCry2 deWcient mice violates the predictions. The model is thereby rejected: the mCry genes do not play a diVerential role, although the opposite responses of mPer mutants to light remain consistent with a functional Evening-Morning diVerentiation.

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Section: Introductionmentioning

confidence: 99%

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

Spoelstra

Daan

2007

J Comp Physiol A

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“…Possibly as a consequence, the bulk of later research has focused on the action of brief light pulses (e.g., DeCoursey, 1960;Pittendrigh and Daan, 1976b;Johnson, 1991). Aschoff and Wever (Aschoff, 1964;Wever, 1966) established the parametric model of entrainment emphasizing continuous changes in the angular velocity of oscillators under the influence of light. They assumed that part of the endogenous cycle is accelerated and another part is decelerated by light.…”

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confidence: 99%

Phase and Period Responses of the Circadian System of Mice (Mus musculus) to Light Stimuli of Different Duration

Comas

Beersma²,

Spoelstra³

et al. 2006

J Biol Rhythms

147

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Phase and period responses of the circadian system of mice (Mus musculus) to light stimuli of different duration Comas, M.; Beersma, D. G. M.; Spoelstra, K.; Daan, S. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. In nature, virtually all circadian rhythms assume the 24.0-h period of the solar day-night cycle. This is due to the entrainment of the endogenous oscillators to the external light-dark cycle, the dominant zeitgeber for the majority of organisms. The process of entrainment is based on differential phase and period responses of the circadian systems to light depending on the phase at which the stimulus is applied. The (1, 3, 4, 6, 9, 12, and 18 h) given once per 11 days in otherwise constant darkness. Light-pulse duration affected both amplitude and shape of the phase response curve. Nine-hour light pulses yielded the maximal amplitude PRC. As in other systems, the circadian period slightly lengthened following delays and shortened following advances. The authors aimed to understand how different parts of the light signal contribute to the eventual phase shift. When PRCs were plotted using the onset, midpoint, and end of the pulse as a phase reference, they corresponded best with each other when using the mid-pulse. Using a simple phase-only model, the authors explored the possibility that light affects oscillator velocity strongly in the 1st hour and at reduced strength in later hours of the pulse due to photoreceptor adaptation. They fitted models based on the 1-h PRC to the data for all light pulses. The best overall correspondence between PRCs was obtained when the effect of light during all hours after the first was reduced by a factor of 0.22 relative to the 1st hour. For the predicted PRCs, the light action centered on average at 38% of the light pulse. This is close to the reference phase yielding best correspondence at 36% of the pulses. The result is thus compatible with an initial major contribution of the onset of the light pulse followed by a reduced effect of light responsible for the differences between PRCs for different duration pulses. The authors suggest that the mid-pulse is a better phase reference than lights-on to plot and compare PRCs of different light-pulse durations.

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“…4) Aschoff's rule: For diurnal animals, the free-running period usually shortens with increasing light intensity; for nocturnal animals, the opposite is commonly observed (Aschoff, 1960). 5) Brighter constant light prolongs activity in diurnal animals, while the opposite applies to nocturnal ani-mals (see, e.g., Aschoff, 1964). All of these phenomena can be simulated with Enright's model (Enright, 1980a(Enright, , 1980b.…”

Section: Pacers In a Networkmentioning

confidence: 99%

Why and How Do We Model Circadian Rhythms?

Beersma

2005

J Biol Rhythms

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In our attempts to understand the circadian system, we unavoidably rely on abstractions. Instead of describing the behavior of the circadian system in all its complexity, we try to derive basic features from which we form a global concept on how the system works. Such a basic concept is a model of reality. The author discusses why it is advantageous or even necessary to transform conceptual models into mathematical formulations. As examples to demonstrate those advantages, the author reviews 4 types of mathematical models: negative feedback models thought to operate within pacemaker cells, models on coupling between pacemaker cells to generate pacemaker output, oscillator models describing the behavior of the composite circadian pacemaker, and models describing how the circadian pacemaker influences behavior.

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Die Tagesperiodik licht- und dunkelaktiver Tiere

Cited by 86 publications

References 0 publications

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

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

Phase and Period Responses of the Circadian System of Mice (Mus musculus) to Light Stimuli of Different Duration

Why and How Do We Model Circadian Rhythms?

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