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Multiple light inputs to a simple clock circuit allow complex biological rhythms

Troein, Carl LU orcid ; Corellou, Florence ; Dixon, Laura E. ; van Ooijen, Gerben ; O'Neill, John S. ; Bouget, François-Yves and Millar, Andrew J. (2011) In Plant Journal 66. p.375-385
Abstract
Circadian clocks are biological timekeepers that allow living cells to time their activity in anticipation of predictable environmental changes. Detailed understanding of the circadian network of higher plants, such as Arabidopsis thaliana, is hampered by the high number of partially redundant genes. However, the picoeukaryotic alga Ostreococcus tauri, which was recently shown to possess a small number of non‐redundant clock genes, presents an attractive alternative target for detailed modelling of circadian clocks in the green lineage. Based on extensive time‐series data from in vivo reporter gene assays, we developed a model of the Ostreococcus clock as a feedback loop between the genes TOC1 and CCA1. The model reproduces the dynamics of... (More)
Circadian clocks are biological timekeepers that allow living cells to time their activity in anticipation of predictable environmental changes. Detailed understanding of the circadian network of higher plants, such as Arabidopsis thaliana, is hampered by the high number of partially redundant genes. However, the picoeukaryotic alga Ostreococcus tauri, which was recently shown to possess a small number of non‐redundant clock genes, presents an attractive alternative target for detailed modelling of circadian clocks in the green lineage. Based on extensive time‐series data from in vivo reporter gene assays, we developed a model of the Ostreococcus clock as a feedback loop between the genes TOC1 and CCA1. The model reproduces the dynamics of the transcriptional and translational reporters over a range of photoperiods. Surprisingly, the model is also able to predict the transient behaviour of the clock when the light conditions are altered. Despite the apparent simplicity of the clock circuit, it displays considerable complexity in its response to changing light conditions. Systematic screening of the effects of altered day length revealed a complex relationship between phase and photoperiod, which is also captured by the model. The complex light response is shown to stem from circadian gating of light‐dependent mechanisms. This study provides insights into the contributions of light inputs to the Ostreococcus clock. The model suggests that a high number of light‐dependent reactions are important for flexible timing in a circadian clock with only one feedback loop. (Less)
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author
; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
in
Plant Journal
volume
66
pages
375 - 385
publisher
Wiley-Blackwell
external identifiers
  • scopus:79954991675
ISSN
1365-313X
DOI
10.1111/j.1365-313X.2011.04489.x
language
English
LU publication?
no
id
eeb3245d-be1a-4910-bd92-866272ddaa55
date added to LUP
2019-05-21 10:22:07
date last changed
2023-02-28 15:44:49
@article{eeb3245d-be1a-4910-bd92-866272ddaa55,
  abstract     = {{Circadian clocks are biological timekeepers that allow living cells to time their activity in anticipation of predictable environmental changes. Detailed understanding of the circadian network of higher plants, such as Arabidopsis thaliana, is hampered by the high number of partially redundant genes. However, the picoeukaryotic alga Ostreococcus tauri, which was recently shown to possess a small number of non‐redundant clock genes, presents an attractive alternative target for detailed modelling of circadian clocks in the green lineage. Based on extensive time‐series data from in vivo reporter gene assays, we developed a model of the Ostreococcus clock as a feedback loop between the genes TOC1 and CCA1. The model reproduces the dynamics of the transcriptional and translational reporters over a range of photoperiods. Surprisingly, the model is also able to predict the transient behaviour of the clock when the light conditions are altered. Despite the apparent simplicity of the clock circuit, it displays considerable complexity in its response to changing light conditions. Systematic screening of the effects of altered day length revealed a complex relationship between phase and photoperiod, which is also captured by the model. The complex light response is shown to stem from circadian gating of light‐dependent mechanisms. This study provides insights into the contributions of light inputs to the Ostreococcus clock. The model suggests that a high number of light‐dependent reactions are important for flexible timing in a circadian clock with only one feedback loop.}},
  author       = {{Troein, Carl and Corellou, Florence and Dixon, Laura E. and van Ooijen, Gerben and O'Neill, John S. and Bouget, François-Yves and Millar, Andrew J.}},
  issn         = {{1365-313X}},
  language     = {{eng}},
  pages        = {{375--385}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Plant Journal}},
  title        = {{Multiple light inputs to a simple clock circuit allow complex biological rhythms}},
  url          = {{http://dx.doi.org/10.1111/j.1365-313X.2011.04489.x}},
  doi          = {{10.1111/j.1365-313X.2011.04489.x}},
  volume       = {{66}},
  year         = {{2011}},
}