Séminaire : On the mechanics of Drosophila thorax morphogenesis

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26 novembre 2010 10:00 » 11:00

Par Isabelle Bonnet , de l’Institut Curie

Résumé :

During the development of multi-cellular organisms, the mechanisms that lead to cell shape change and tissue movement remain poorly understood. In a team involving biologists and physicists, we investigate the mechanical

forces driving the multi-scale dynamics during the morphogenesis of the fruit-fly (Drosophila) dorsal thorax.

Through the ubiquitous expression of fluorescent adhesion molecules in living animals, it is possible to label all the cells membranes (ECad:GFP) and perform the time-lapse confocal microscopy imaging throughout the metamorphosis from larva to adult. The quantitative analysis of cell displacements and tissue movements allows the measurement of local deformation rates. We thus construct spatio-temporal maps of the dynamics within the Drosophila dorsal thorax. These maps reveal that the dorsal thorax undergoes two main morphogenetic movements. In the posterior part of the tissue (the scutellum) cells undergo an elongation along the dorsal-ventral axis. In the anterior part of the tissue (the notum), cells flow towards the head of the animal.

In parallel, we probe the mechanical forces driving these morphogenetic events. In the regions undergoing cell and tissue movements, we use two-photon microscopy to perform laser ablation of living animals. We determine the stress within the tissue before ablation by analyzing tissue relaxation. As a result, we show that stress increases and becomes anisotropic as tissue undergoes morphogenesis.

Finally, we are analyzing the cell and tissue movements in mutants affecting the tumor suppressor Fat pathways to understand the molecular basis at the origin of stress and tissue movement regulation.

Altogether our approach should allow the description of the mechanisms by which signaling pathways locally modulate cell or tissue mechanics in order to generate tissue shape.

Rendez-vous à l’ ESPCI ParisTech, en amphithéâtre Langevin à 11h.

Contact : ramiro[at]pmmh.espci.fr

10 Rue Vauquelin, 75005 Paris