Dynamics of cyanobacterial clocks and yeast memory reveal the effects of global noise

11 May 2007

Juan Pedraza
Paulsson Lab, Department of Systems Biology
Harvard Medical School


Single-cell fluorescent measurements have become commonplace, allowing the study of the dynamics of cell populations. Studies of genetic noise have progressed to the point where steady-state distributions can be predicted and the dynamics of the noise can be measured. At the same time, single-molecule measurements are starting to reveal additional complexity in the underlying processes. What information on biological systems can we extract from looking at the dynamics of noise, and conversely, how much predictive power do we have on it when even the steady state noise can be dependent on very complex processes?

I will present new experimental results on the noise of a gene controlled by a circadian oscillator in cyanobacteria. I will also show some curious effects of not being in steady state and show an example of how analytical predictions of the noise dynamics can be used to reveal new underlying mechanisms. I will discuss the successful prediction of noise dynamics in the E. coli lactose uptake system and present ongoing work on the dynamics of the galactose uptake system in S. cerevisiae. This system will be used to illustrate the effects of external and global noise on the stability of cellular memory.

If time permits, I will present new theoretical results on the effects of molecular dynamics on the steady-state noise, which explain how previous studies based on simple models have had such success.

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