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The Importance of Stochastic Effects for Explaining Entrainment in the Zebrafish Circadian Clock.

Heussen R, Whitmore D - Comput Math Methods Med (2015)

Bottom Line: Here we investigate how the circadian clock is entrained by external cues such as light.Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal.Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.

View Article: PubMed Central - PubMed

Affiliation: CoMPLEX, UCL, Physics Building, Gower Place, London WC1E 6BT, UK.

ABSTRACT
The circadian clock plays a pivotal role in modulating physiological processes and has been implicated, either directly or indirectly, in a range of pathological states including cancer. Here we investigate how the circadian clock is entrained by external cues such as light. Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal. Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.

No MeSH data available.


Related in: MedlinePlus

15-minute light pulse experiments at varying intensity. Bioluminescence trace of Per1 reporter cell line. Cells were kept in the dark for 5 days before data recording. A 15-minute light pulse of varying strength as indicated was administered at about 24 hours (control, no light pulse). At the end of the experiment, cells were kept in LD for two days. This was done to confirm that cells were still healthy and responded to light as expected. (a) Raw data; (b) detrended data. The black and white boxes at the bottom of the graph indicate lights on (white) and lights off (black).
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fig2: 15-minute light pulse experiments at varying intensity. Bioluminescence trace of Per1 reporter cell line. Cells were kept in the dark for 5 days before data recording. A 15-minute light pulse of varying strength as indicated was administered at about 24 hours (control, no light pulse). At the end of the experiment, cells were kept in LD for two days. This was done to confirm that cells were still healthy and responded to light as expected. (a) Raw data; (b) detrended data. The black and white boxes at the bottom of the graph indicate lights on (white) and lights off (black).

Mentions: The experiment was carried out as described above with light pulse durations of 15 minutes and 1 hour and light intensities ranging from 0.1 to 1000 μW cm−2, where a short duration and low intensities were chosen to determine what amount of light may be sufficient to cause an effect. The wavelength spectrum was 400–700 nm, and assuming a wavelength of 520 nm this range of irradiance corresponds to a photon flux of 0.0043 to 43 μmol m−2 s−1. The bioluminescence traces for the 15-minute and 1-hour experiments can be seen in Figures 2 and 3, respectively.


The Importance of Stochastic Effects for Explaining Entrainment in the Zebrafish Circadian Clock.

Heussen R, Whitmore D - Comput Math Methods Med (2015)

15-minute light pulse experiments at varying intensity. Bioluminescence trace of Per1 reporter cell line. Cells were kept in the dark for 5 days before data recording. A 15-minute light pulse of varying strength as indicated was administered at about 24 hours (control, no light pulse). At the end of the experiment, cells were kept in LD for two days. This was done to confirm that cells were still healthy and responded to light as expected. (a) Raw data; (b) detrended data. The black and white boxes at the bottom of the graph indicate lights on (white) and lights off (black).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663325&req=5

fig2: 15-minute light pulse experiments at varying intensity. Bioluminescence trace of Per1 reporter cell line. Cells were kept in the dark for 5 days before data recording. A 15-minute light pulse of varying strength as indicated was administered at about 24 hours (control, no light pulse). At the end of the experiment, cells were kept in LD for two days. This was done to confirm that cells were still healthy and responded to light as expected. (a) Raw data; (b) detrended data. The black and white boxes at the bottom of the graph indicate lights on (white) and lights off (black).
Mentions: The experiment was carried out as described above with light pulse durations of 15 minutes and 1 hour and light intensities ranging from 0.1 to 1000 μW cm−2, where a short duration and low intensities were chosen to determine what amount of light may be sufficient to cause an effect. The wavelength spectrum was 400–700 nm, and assuming a wavelength of 520 nm this range of irradiance corresponds to a photon flux of 0.0043 to 43 μmol m−2 s−1. The bioluminescence traces for the 15-minute and 1-hour experiments can be seen in Figures 2 and 3, respectively.

Bottom Line: Here we investigate how the circadian clock is entrained by external cues such as light.Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal.Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.

View Article: PubMed Central - PubMed

Affiliation: CoMPLEX, UCL, Physics Building, Gower Place, London WC1E 6BT, UK.

ABSTRACT
The circadian clock plays a pivotal role in modulating physiological processes and has been implicated, either directly or indirectly, in a range of pathological states including cancer. Here we investigate how the circadian clock is entrained by external cues such as light. Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal. Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.

No MeSH data available.


Related in: MedlinePlus