The SLOOP project: Simulations, Parallel Object-Oriented Languages, Interconnection Networks

International audienc

Very-Long-Chain Fatty Acids Are Involved in Polar Auxin Transport and Developmental Patterning in \u3ci\u3eArabidopsis\u3c/i\u3e

Very-long-chain fatty acids (VLCFAs) are essential for many aspects of plant development and necessary for the synthesis of seed storage triacylglycerols, epicuticular waxes, and sphingolipids. Identification of the acetyl-CoA carboxylase PASTICCINO3 and the 3-hydroxy acyl-CoA dehydratase PASTICCINO2 revealed that VLCFAs are important for cell proliferation and tissue patterning. Here, we show that the immunophilin PASTICCINO1 (PAS1) is also required for VLCFA synthesis. Impairment of PAS1 function results in reduction of VLCFA levels that particularly affects the composition of sphingolipids, known to be important for cell polarity in animals. Moreover, PAS1 associates with several enzymes of the VLCFA elongase complex in the endoplasmic reticulum. The pas1 mutants are deficient in lateral root formation and are characterized by an abnormal patterning of the embryo apex, which leads to defective cotyledon organogenesis. Our data indicate that in both tissues, defective organogenesis is associated with the mistargeting of the auxin efflux carrier PIN FORMED1 in specific cells, resulting in local alteration of polar auxin distribution. Furthermore, we show that exogenous VLCFAs rescue lateral root organogenesis and polar auxin distribution, indicating their direct involvement in these processes. Based on these data, we propose that PAS1 acts as a molecular scaffold for the fatty acid elongase complex in the endoplasmic reticulum and that the resulting VLCFAs are required for polar auxin transport and tissue patterning during plant development

Les sociétés rurales face aux changements climatiques et environnementaux en Afrique de l’Ouest

L’avenir de l'Afrique de l'Ouest dépend de la capacité de son agriculture à assurer la sécurité alimentaire de sa population, qui devrait doubler en vingt ans, tout en faisant face aux risques nouveaux engendrés par le réchauffement climatique. En effet, les modifications de température et de précipitations déjà à l’oeuvre, et qui devraient s’amplifier, auront dans un futur proche des répercussions importantes sur la production agricole et sur les ressources en eau de cette partie du continent africain. L’adaptation des sociétés rurales aux risques climatiques est une des clés pour relever ce nouveau défi. Pour mieux en connaître le potentiel, les processus et les barrières, cet ouvrage analyse les évolutions récentes et en cours du climat et de l’environnement, et étudie comment les sociétés rurales les perçoivent et les intègrent : quels sont les impacts de ces changements, quelles vulnérabilités mais aussi quelles nouvelles opportunités entraînent-ils ? Comment les populations s’y adaptent-elles, et quelles innovations mettent-elles en oeuvre, alors que les effets induits par le climat interagissent avec les changements sociaux, politiques, économiques et techniques en cours sur le continent ? En associant des chercheurs français et africains (climatologues, agronomes, hydrologues, écologues, démographes, géographes, anthropologues, sociologues…) dans une approche interdisciplinaire, cet ouvrage apporte une contribution précieuse pour mieux anticiper les risques climatiques et évaluer les capacités des sociétés africaines à y faire face

Rural societies in the face of climatic and environmental changes in West Africa

The future of West Africa depends on the capacity of its agriculture to ensure the food security of the population, which should double in the next 20 years, while facing up to the new risks resulting from climate warming. Indeed, the changes in temperature and precipitations already operating and that should become more marked will have serious effects on agricultural production and water resources in this part of Africa in the near future. One of the keys to meeting this new challenge is the adaptation of rural societies to climate risks. To gain better knowledge of the potential, processes and barriers, this book analyses recent and ongoing trends in the climate and the environment and examines how rural societies perceive and integrate them: what are the impacts of these changes, what vulnerabilities are there but also what new opportunities do they bring? How do the populations adapt and what innovations do they implement—while the climate-induced effects interact with the social, political, economic and technical changes that are in motion in Africa? By associating French and African scientists (climatologists, agronomists, hydrologists, ecologists, demographers, geographers, anthropologists, sociologists and others) in a multidisciplinary approach, the book makes a valuable contribution to better anticipation of climatic risks and the evaluation of African societies to stand up to them