Regulation of cellular morphogenesis and growth

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Regulation of cellular morphogenesis and growth

Bacteria are fascinating systems far from equilibrium that self-replicate robustly yet show large fluctuations in single-cell behavior. To understand the importance of fluctuations for cellular behavior and robust self-replication we study bacterial physiology at the single-cell level during steady-state growth and in fluctuation environments using microfluidic chambers and high-resolution microscopy.
We are particularly interested in the regulation of growth and of macroscopic cell size, which are not understood in any organism today. To monitor cellular behavior we use high-resolution fluorescence microscopy and image analysis. We compare our experimental data to theoretical models of regulation and of cellular morphogenesis.

1) Analysis of bacterial growth and gene expression

In this project we measure the growth and expression levels of genes and proteins in individual cells under the microscope. We subsequently extract temporal cross-correlations between protein levels and growth rate, following an approach recently published [1]. This allows us to determine temporal organization and constraints on single-cell fluctuations. The experiments inform stochastic models of growth-rate control that we are developing together with collaborators. We currently aim to improve the accuracy of our measurements and extend the range of physiological quantities tested, in particular with regards to possible physical determinants of cell size. The project has room for both state-of-theart experiments and computational/theoretical work.

2) Cell mechanics and its role for bacterial cell shape

Similarly to plant cells, bacterial cell shape is determined by a rigid cell wall. During growth the cell wall constantly needs to be plastically and enzymatically remodeled, in order to make space for the accumulation of intra-cellular proteins. In this project we study the effect of mechanical forces on bacterial cell-shape deformation. We already know that mechanics is involved in the adaptation of cell shape to confining geometries and or to externally applied forces [2]. However, it is yet unknown how
these cell-shape changes come about, i.e., how the cell wall is remodeled to assume a deformed morphology. In this project we study the effects of externally applied mechanical forces on cell shape and on the localization and behavior of important proteins involved in cell-wall remodeling.

[1] Kiviet et al. Nature 2015. [2] Amir et al. PNAS 2014

e-mail : sven@pasteur.fr Phone number : 01 45 68 80 16
Web page : https://research.pasteur.fr/en/team/microbial-morphogenesis-and-growth/

Accès rapides

Prochain Séminaire de la FIP :
Accéder au programme

Retrouvez toutes les informations pour vos stages :
Stages L3
Stages M1 ICFP
Stages M2 ICFP

Actualités : Séminaire de Recherche ICFP
du 6 au 10 novembre 2017 :

Retrouvez le programme complet

Emploi du temps 2017-2018 :
Emploi du temps L3
Emploi du temps M1 ICFP
Emploi du temps M2 ICFP

Contact - Secrétariat de l’enseignement :
Tél : 01 44 32 35 61
enseignement@phys.ens.fr