Skip to main content
Article thumbnail
Location of Repository

Quantitative analysis of regulatory flexibility under changing environmental conditions\ud

By Kieron D. Edwards, Ozgur E. Akman, Kirsten Knox, P. J. Lumsden, Adrian W. Thomson, Paul E. Brown, Alexandra Pokhilko, Laszlo Kozma-Bognar, Ferenc Nagy, D. A. Rand and A. J. Millar


The circadian clock controls 24-h rhythms in many biological processes, allowing appropriate timing of biological rhythms relative to dawn and dusk. Known clock circuits include multiple, interlocked feedback loops. Theory suggested that multiple loops contribute the flexibility for molecular rhythms to track multiple phases of the external cycle. Clear dawn- and dusk-tracking rhythms illustrate the flexibility of timing in Ipomoea nil. Molecular clock components in Arabidopsis thaliana showed complex, photoperiod-dependent regulation, which was analysed by comparison with three contrasting models. A simple, quantitative measure, Dusk Sensitivity, was introduced to compare the behaviour of clock models with varying loop complexity. Evening-expressed clock genes showed photoperiod-dependent dusk sensitivity, as predicted by the three-loop model, whereas the one- and two-loop models tracked dawn and dusk, respectively. Output genes for starch degradation achieved dusk-tracking expression through light regulation, rather than a dusk-tracking rhythm. Model analysis predicted which biochemical processes could be manipulated to extend dusk tracking. Our results reveal how an operating principle of biological regulators applies specifically to the plant circadian clock

Topics: QK
Publisher: Nature Publishing Group
Year: 2010
OAI identifier:

Suggested articles


  1. (2007). 16: 956–966 LumsdenPJ,YoungsJA,ThomasB,Vince-PrueD(1995)Evidencethat photoperiodic, dark time measurement in pharbitis-nil involves a circadian rather than a semidian rhythm. Plant Cell Environ 18: 1403–1410 doi
  2. (2000). Acad Sci USA 107: 9458–9463 H a r m e rS L ,H o g e n e s c hJ B ,S t r a u m eM ,C h a n gH S ,H a nB ,Z h uT
  3. (1998). Chem 281: 11815–11818 Ouyang
  4. (2002). Coordinated transcription of key pathways in the mouse by the circadian clock. doi
  5. (2005). LUX ARRHYTHMOencodes a Myb domainprotein essential for circadian rhythms. Proc Natl Acad Sci USA 102: 10387–10392 Hazlerigg D, Loudon A (2008) New insights into ancient seasonal life timers. Curr Biol 18: R795–R804 Heide OM, King RW,
  6. (2004). MS (2005a) Modelling genetic networks with noisy and varied experimental data: the circadian clock in Arabidopsis thaliana. doi
  7. (2000). Physiol 50: 290–303 Jagota A, de la Iglesia HO, Schwartz WJ
  8. (2010). Robustness from flexibility in the fungal circadian clock. doi
  9. (2008). The circadian clock in Arabidopsis roots is a simplifiedslaveversion of the clockin shoots.Science 322: 1832–1835 doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.