The fate of mitochondria during platelet activation

International audiencePlatelet mitochondria undergo a fission step during platelet activation. • The fission of platelet mitochondria correlates with a switch from a predominant mitochondrial to a more glycolytic energy production. Blood platelets undergo several successive motor-driven reorganizations of the cytoskeleton when they are recruited to an injured part of a vessel. These reorganizations take place during the platelet activation phase, the spreading process on the injured vessel or between fibrin fibers of the forming clot, and during clot retraction. All these steps require a lot of energy, especially the retraction of the clot when platelets develop strong forces similar to those of muscle cells. Platelets can produce energy through glycolysis and mitochondrial respiration. However, although resting platelets have only 5 to 8 individual mitochondria, they produce adenosine triphosphate predominantly via oxidative phosphorylation. Activated, spread platelets show an increase in size compared with resting platelets, and the question arises as to where the few mitochondria are located in these larger platelets. Using expansion microscopy, we show that the number of mitochondria per platelet is increased in spread platelets. Live imaging and focused ion beam-scanning electron microscopy suggest that a mitochondrial fission event takes place during platelet activation. Fission is Drp1 dependent because Drp1-deficient platelets have fused mitochondria. In nucleated cells, mitochondrial fission is associated with a shift to a glycolytic phenotype, and using clot retraction assays, we show that platelets have a more glycolytic energy production during clot retraction and that Drp1-deficient platelets show a defect in clot retraction

Draft convention on the international status of environmentally- displaced persons

Prieur Michel, Marguénaud Jean-Pierre, Monediaire Gérard, Betaille Julien, Drobenko Bernard, Gouguet Jean-Jacques, Lavieille Jean-Marc, Nadaud Séverine, Roets Damien, Bouin Frédéric, Burgat Florence, Cournil Christel, Dinh Van, Juste Ballesta José, Lador Yves, Mazzega Pierre, Michelot Agnès, Shelton Dinah. Draft convention on the international status of environmentally- displaced persons. In: Revue Européenne de Droit de l'Environnement, n°4, 2008. projet de convention relative au statut international des déplacés environnementaux. pp. 395-406

Projet de convention relative au statut international des déplacés environnementaux

Prieur Michel, Marguénaud Jean-Pierre, Monediaire Gérard, Betaille Julien, Drobenko Bernard, Gouguet Jean-Jacques, Lavieille Jean-Marc, Nadaud Séverine, Roets Damien, Bouin Frédéric, Burgat Florence, Cournil Christel, Dinh Van, Juste Ballesta José, Lador Yves, Mazzega Pierre, Michelot Agnès, Shelton Dinah. Projet de convention relative au statut international des déplacés environnementaux. In: Revue Européenne de Droit de l'Environnement, n°4, 2008. projet de convention relative au statut international des déplacés environnementaux. pp. 381-393

Approche multi-échelle du fonctionnement des éco-agrosystèmes d'Afrique de l'Ouest dans le cadre du projet AMMA

6 pages, octobre 2005Rapport de restitution comité ECCO

On the Use of Hydrological Models and Satellite Data to Study the Water Budget of River Basins Affected by Human Activities: Examples from the Garonne Basin of France

Natural and anthropogenic forcing factors and their changes significantly impact water resources in many river basins around the world. Information on such changes can be derived from fine scale in situ and satellite observations, used in combination with hydrological models. The latter need to account for hydrological changes caused by human activities to correctly estimate the actual water resource. In this study, we consider the catchment area of the Garonne river (in France) to investigate the capabilities of space-based observations and up-to-date hydrological modeling in estimating water resources of a river basin modified by human activities and a changing climate. Using the ISBA-MODCOU and SWAT hydrological models, we find that the water resources of the Garonne basin display a negative climate trend since 1960. The snow component of the two models is validated using the moderate-resolution imaging spectroradiometer snow cover extent climatology. Crop sowing dates based on remote sensing studies are also considered in the validation procedure. Use of this dataset improves the simulated evapotranspiration and river discharge amounts when compared to conventional data. Finally, we investigate the benefit of using the MAELIA multi-agent model that accounts for a realistic agricultural and management scenario. Among other results, we find that changes in crop systems have significant impacts on water uptake for agriculture. This work constitutes a basis for the construction of a future modeling framework of the sociological and hydrological system of the Garonne river region