Dynamic description of the circadian clock entrainment in cyanobacteria by a phase oscillator model

Abstract : Cyanobacteria are the simplest known organism with a circadian clock. This clock produces stable rhythms with a period close to 24h and can be entrained to exactly 24h by external time cues like illumination or temperature cycles. In this work we show that this biological clock behaves like a phase oscillator. Furthermore its behaviour under the influence of an external entrainment can be discribed by the simple Adler model. For this we performed experiments on populations and used either illumination or temperature cycles to entrain the circadian clock to different phases. We detail the experiment set-up that allows to monitor the circadian clock of the bacteria continuously over 2 weeks, show how to unmask additional perturbation of the bioluminescence reporter and quantify the coupling strength between the clock and the external extrainment. Fitting the model to the experimental data we show that it indeed reproduces very well the observed behaviour. Via simulations we infer into the effects of a distribution of initial phases inside the populations, as well as the effect of possible noise on the phase or a distribution of proper frequencies. We also propose a new concept for single cell devices to infer further the effect of noise on this biological clock. These devices are designed for long term (>20 generations) observation of individual bacteria inside a population.
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Contributor : Christoph Weiss-Schaber <>
Submitted on : Wednesday, July 7, 2010 - 3:46:38 PM
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  • HAL Id : tel-00498487, version 1




Christoph Weiss-Schaber. Dynamic description of the circadian clock entrainment in cyanobacteria by a phase oscillator model. Biological Physics [physics.bio-ph]. Université Joseph-Fourier - Grenoble I, 2010. English. ⟨tel-00498487⟩



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