In our work, we have employed the chemotaxis network responsible for the motion of E. coli bacteria as a model system for the general study of signal transduction networks. We asked whether there were specific molecular events that could cause behavioral variability in an individual cell. By developing a single-cell approach we were able to characterize the design principles of the signal transduction network in bacteria (chemotaxis). We found that the inherent randomness (noise) in the chemical reactions taking place in the intracellular signal processing was a "tuneable" source of behavioral variability.
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The purpose of this project is to develop a software framework to study the design principles of simple intracellular computations in living organisms. A multi-level software, named AgentCell, has been developed to study important properties of the E. Coli chemotaxis network and the coordinated motion of bacterial cells in direct response to environmental stimuli, Emonet et al., bioinformatics (2005). The chemotaxis network for E. coli serves as a model system because it is well characterized and experimentally accessible. The multi-level simulation models the dynamics of the signal transduction networks within cells at one (micro-) level, and simulates the movement of the cells through a medium at the other (macro-) level.
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Using fluorescence correlation spectroscopy (FCS), we monitored in real-time and within a single bacterium of E. coli the dynamics of synthesis and the degradation of a specific RNA transcript. The goal of this study is to characterize the relationship between the dynamics and the design of simple transcriptional networks at the single cell level.Nearly half a century ago the discovery of messenger RNA as an "unstable intermediate" established RNA instability as a key dynamical property in the molecular organisation of life. The balance between the kinetics of synthesis and the degradation of RNA transcripts exhibits a primitive example of molecular adaptation of gene expression. read more...
As modern biology unveils the architecture of a growing number of large intracellular networks, their intricate topology raises a general question: Is there a specific network topology that confers some kind of evolutionary advantage?In this project, we ask how networks with distinct topologies can evolve towards a pre-established target... read more...
