  The microscopic green alga Ostreococcus tauri is rapidly emerging as a
promising model organism in the green lineage. In particular, recent results by
Corellou et al. [Plant Cell, 21, 3436 (2009)] and Thommen et al. [PLoS Comput.
Biol. 6, e1000990 (2010)] strongly suggest that its circadian clock is a
simplified version of Arabidopsis thaliana clock, and that it is architectured
so as to be robust to natural daylight fluctuations. In this work, we analyze
time series data from luminescent reporters for the two central clock genes
TOC1 and CCA1 and correlate them with microarray data previously analyzed. Our
mathematical analysis strongly supports both the existence of a simple two-gene
oscillator at the core of Ostreococcus tauri clock and the fact that its
dynamics is not affected by light in normal entrainment conditions, a signature
of its robustness.
