Laboratoire de Chimie Bactérienne UMR 7283

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Accueil > Research > LATIFI > Theme

Cellular Differentiation and Signalling

Equipe Latifi

We are interested in cell signaling with an emphasis on the cellular differentiation in bacteria. Our model is the filamentous cyanobacterium Anabaena PCC 7120. When combined nitrogen becomes limiting, nitrogen-fixing cells called heterocysts differentiate from vegetative cells at semi-regular intervals along the filaments (every 10 to 15 vegetative cells). In the heterocysts, the photosynthesis turns off allowing the oxygen-sensitive nitrogenase to functionAnabaena is thus a prokaryotic model to study both cell differentiation and developmental pattern formation. These developmental processes are spatio-temporally regulated.

Using genetics, cellular biology, and more recently single-cell based approaches, we aim to address major developmental questions of differentiation in Anabaena : What governs the establishment and the persistence on the differentiation pattern ? What discriminates a future-heterocyst cell from its neighbors ? What dictates the “differentiation timing” ?

Besides this developmental project, we are also interested in engineering Anabaena in order to conciliate the oxygen-sensitive hydrogen production with photosynthesis. Since, Sunlight, CO2 and water are the only prerequisite to cyanobacteria growth, these organisms are candidate of choice for the production of biofuels.


Figure 1 : Vegetative growth

Anabaena grows in multicellular filaments. Here, the FtsZ-ring that assembles during vegetative cell division is visualized

Figure 2 : Cell differentiation follows a pattern

When fixed nitrogen becomes limiting, differentiate cells referred as heterocysts (green) are formed every 10 to 15 vegetative cells (red).

Figure 3 : Cell differentiation is temporally regulated

 The development of a vegetative cell into a pro-heterocyst and into a mature heterocyst is shown.