Septin filament organization in Saccharomyces cerevisiae.

Septins are a family of GTP-binding, membrane-interacting cytoskeletal proteins, highly conserved and essential in all eukaryotes (with the exception of plants). Septins play important roles in a number of cellular events that involve membrane remodeling and compartmentalization. One such event is cytokinesis, the last stage of cell division. While cytokinesis is ultimately achieved via the mechanical contraction of an actomyosin ring at the septum, determination of the location where cytokinesis will take place, and recruitment of factors involved in signaling events leading to septation requires the activity of septins. We are working towards dissecting the properties of septins from the budding yeast Saccharomyces cerevisiae, where they were first discovered as cell cycle mutants. In our studies we have employed several complementary electron microscopy techniques to describe the organization and structure of septins both in vitro and in situ

Problem solving methods as Lessons Learned System instrumentation into a PLM tool

Among the continuous improvement tools of the performance in enterprise, the experience feedback represents undoubtedly an effective lever of progress by offering important prospects for a progression in almost all the industrial sectors. However, several reserves to its use slow down the diffusion of its employment. We are interested in the installation of experience feedback system in a partner enterprise. In this paper, we propose an instrumentation of a Lessons Learned System (LLS) by problem solving methods (PSM) and its integration with a product lifecycle management (PLM). These proposals support an improvement of LLS performance and a facility of his application

Proposition d'amélioration d'un système de retour d'expérience

L’objet de cette communication est de présenter des travaux portant sur le déploiement d’un système de retour d’expérience dans un progiciel PLM (Product Lifecycle Management). Ces travaux sont réalisés en partenariat avec la société Saft Bordeaux, spécialisée dans la conception et la fabrication de systèmes de batteries complexes. Nous commençons par définir la notion de système de retour d’expérience avec ses trois phases clefs (capitalisation, traitement et exploitation) qui le composent. Puis, à l’aide d’un audit réalisé auprès d’une trentaine d’acteurs impliqués dans le développement des produits, nous analysons les pratiques et outils actuellement employés à la Saft. De cette analyse, nous identifions les freins et les attentes des acteurs pour pouvoir réaliser un retour d’expérience efficient. Enfin, face à ces résultats, nous présentons les principes de la solution mise en oeuvre et les intérêts d’avoir couplé un système REx (Retour d'Expérience) à un PLM. Nous concluons en présentant les perspectives importantes qu’offre un tel travail

Intégration d'un système de Retour d'Expériences à un PLM

Les travaux présentés dans cette thèse s’inscrivent dans une problématique d’amélioration continue appliquée aux produits et aux processus industriels, par la mise en place d’un système de Retour d’Expérience (REx) couplé au système PLM (Product Lifecycle Management) de gestion du cycle de vie du produit. Les développements, menés dans le cadre d’un partenarial industriel, ciblent l’établissement d’une solution de valorisation du patrimoine immatériel de l’entreprise, constitué des expériences et des connaissances détenues par les experts métier. L’objectif visé est d’assurer la pérennisation de cette expertise, la prévention et la limitation des erreurs et l’application de bonnes pratiques dans une démarche générale d’amélioration des produits et des processus. La solution est portée par la mise en place d’un système REx appliqué aux connaissances tacites et explicites impliquées dans les activités techniques de l'entreprise et visant à capitaliser au fur et à mesure les informations métier, porteuses de sens. L’intégration du REx au système PLM permet de lever une part des difficultés d’appropriation par les experts métier, utilisateurs du système REx. L’ancrage de ce REx aux méthodes de résolution de problèmes (PSM, Problem Solving Methods) induit une instrumentation tout à fait performante pour l’acquisition des connaissances tacites issues d’événements négatifs. L’extension aux processus d’évolution des Normes Techniques qui formalisent les règles métier de l’entreprise permet leur évolution vers des connaissances explicites. Le caractère non intrusif du système REx dans son utilisation est assuré par un couplage étroit au processus de Gestion des Modifications du PLM, la capitalisation des informations étant naturellement induite par la démarche mise en œuvre dans ce processus. Au final, le système REx proposé et instrumenté dans l’outil PLM permet, en différentes étapes, de capitaliser, de traiter puis d’exploiter dans des formes performantes le patrimoine immatériel mis en exergue au cours des expériences de résolution de problèmes produit ou processus. ABSTRACT : The work presented in this thesis considers continuous improvement issues which are applied to industrial products and processes through the implementation of a Lesson Learned System (LLS) coupled with the Company's Product Lifecycle Management (PLM) system. As an industrial partnership, these developments aim to increase the value of the intangible assets of the business including the business agent’s experiences and knowledge. In order to ensure the sustainability of expertise, to prevent errors and to encourage the application of good practices, all within a general approach of product improvement. The solution relies on the implementation of the LLS process which is applied to tacit and explicit knowledge related to the technical activities of the company. The integration of the LLS and PLM Systems removes some of the difficulties of ownership of business agents. The implementation of LLS and Problem Solving Methods (PSM) infers an efficient instrumentation for the acquisition of tacit knowledge. The extension of the evolution processes of technical documents that formalise the techincal business rules allows its evolution towards explicit knowledge. Using non-intrusive LLS is provided by close coupling with the process of Change Management (CM) where information capitalisation is naturally led by the approach implemented in this processes. Finally, the proposed and instrumented LLS in the PLM tool allows to efficiently capitalise, process, and exploit the intangible capital of the company (information and knowledge) highlighted during the modification experiments of product data

Septin‐based readout of PI(4,5)P2 incorporation into membranes of giant unilamellar vesicles

International audienceSeptins constitute a novel class of cytoskeletal proteins. Budding yeast septins self-assemble into non-polar filaments bound to the inner plasma membrane through specific interactions with L-α-phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). Biomimetic in vitro assays using Giant Unilamellar Vesicles (GUVs) are relevant tools to dissect and reveal insights in proteins-lipids interactions, membrane mechanics and curvature sensitivity. GUVs doped with PI(4,5)P2 are challenging to prepare. This report is dedicated to optimize the incorporation of PI(4,5)P2 lipids into GUVs by probing the proteins-PI(4,5)P2 GUVs interactions. We show that the interaction between budding yeast septins and PI(4,5)P2 is more specific than using usual reporters (phospholipase C1). Septins have thus been chosen as reporters to probe the proper incorporation of PI(4,5)P2 into giant vesicles. We have shown that electro-formation on platinum wires is the most appropriate method to achieve an optimal septin-lipid interaction resulting from an optimal PI(4,5)P2 incorporation for which, we have optimized the growth conditions. Finally, we have shown that PI(4,5)P2 GUVs have to be used within a few hours after their preparation. Indeed, over time, PI(4,5)P2 is expelled from the GUV membrane and the PI(4,5)P2 concentration in the bilayer decreases

Author Correction:Human ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation

An amendment to this paper has been published and can be accessed via a link at the top of the paper

A Tale of Two Oxidation States: Bacterial Colonization of Arsenic-Rich Environments

Microbial biotransformations have a major impact on contamination by toxic elements, which threatens public health in developing and industrial countries. Finding a means of preserving natural environments—including ground and surface waters—from arsenic constitutes a major challenge facing modern society. Although this metalloid is ubiquitous on Earth, thus far no bacterium thriving in arsenic-contaminated environments has been fully characterized. In-depth exploration of the genome of the β-proteobacterium Herminiimonas arsenicoxydans with regard to physiology, genetics, and proteomics, revealed that it possesses heretofore unsuspected mechanisms for coping with arsenic. Aside from multiple biochemical processes such as arsenic oxidation, reduction, and efflux, H. arsenicoxydans also exhibits positive chemotaxis and motility towards arsenic and metalloid scavenging by exopolysaccharides. These observations demonstrate the existence of a novel strategy to efficiently colonize arsenic-rich environments, which extends beyond oxidoreduction reactions. Such a microbial mechanism of detoxification, which is possibly exploitable for bioremediation applications of contaminated sites, may have played a crucial role in the occupation of ancient ecological niches on earth

Structure, Function, and Evolution of the Thiomonas spp. Genome

Bacteria of the Thiomonas genus are ubiquitous in extreme environments, such as arsenic-rich acid mine drainage (AMD). The genome of one of these strains, Thiomonas sp. 3As, was sequenced, annotated, and examined, revealing specific adaptations allowing this bacterium to survive and grow in its highly toxic environment. In order to explore genomic diversity as well as genetic evolution in Thiomonas spp., a comparative genomic hybridization (CGH) approach was used on eight different strains of the Thiomonas genus, including five strains of the same species. Our results suggest that the Thiomonas genome has evolved through the gain or loss of genomic islands and that this evolution is influenced by the specific environmental conditions in which the strains live