# Réseaux génétiques : conception, modélisation et dynamique

Abstract : This thesis presents a series of works all dealing with the structure and the dynamics of genetic networks. After a first part introducing various recent works in the field, we propose a method to design genetic networks by evolution in silico. This procedure aims at designing genetic motifs performing a given function without any constraints on their structure. With the help of the algorithm, we found both new and well-known motifs. We also compare the obtained modules to real ones and propose some possible applications of the algorithm. In a second part, we analyze the properties of one of the modules found with the help of the algorithm which happens to be overrepresented in real genetic networks. The so-called Mixed Feedback Loop'' consists of two proteins A and B. Protein A regulates transcription of gene b, and the two proteins can form an inactive dimer. A detailed mathematical analysis is proposed. We show that this module can act either as a genetic switch, either as an oscillator. A phase diagram and a precise description of the limit-cycle is also derived analytically. Finally, in the third part, we focus on circadian clocks, which are important examples of genetic oscillators. The general properties of these oscillators are recalled and a model for the Neurospora crassa circadian clock is proposed. We especially show the importance of a second feedback loop to explain the robustness of the period of the oscillations with the variation of parameters.
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Cited literature [138 references]

https://tel.archives-ouvertes.fr/tel-00010681
Contributor : Paul François <>
Submitted on : Tuesday, October 18, 2005 - 6:17:43 PM
Last modification on : Thursday, October 29, 2020 - 3:01:26 PM
Long-term archiving on: : Friday, April 2, 2010 - 10:47:58 PM

### Identifiers

• HAL Id : tel-00010681, version 1

### Citation

Paul François. Réseaux génétiques : conception, modélisation et dynamique. Physique [physics]. Université Paris-Diderot - Paris VII, 2005. Français. ⟨tel-00010681⟩

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