Sterols associated with small unilamellar vesicles (SUVs): intrinsic mobility role for 1H NMR detection.

International audienceSmall unilamellar vesicles (SUVs) of phospholipids are often used as a membrane model system for studying the interaction of molecules. When using NMR under the standard liquid-state conditions, SUV phospholipid proton spectra can be recorded, exhibiting sharp signals. This is not only because of the fast vesicular tumbling but also because of the combination of this tumbling with the individual motion of the lipids inside the bilayer. This appears evident because addition of cholesterol is responsible of broader resonances because of the slowing down of the lipid motion. On the other hand, no (1)H signal is detected for cholesterol in the bilayer. This lack of detection of the inserted molecules explains why generally SUVs are not considered as a good model for NMR studies under the standard liquid-state conditions. Here, we use two other sterols in order to demonstrate that an increase of the molecular mobility inside the bilayer could allow the detection of their proton resonances. For desmosterol and lanosterol, which show higher mobility inside the bilayer, with increasing lateral diffusion rates, (1)H sterol signals are detected in contrast to cholesterol. For the fast diffusing lanosterol, no significant improvement in detection is observed using deuterated lipids, demonstrating that homonuclear dipolar coupling is fully averaged out. Furthermore, in the case of low mobility such as for cholesterol, the use of a fast magic angle spinning probe is shown to be efficient to recover the full proton spectrum

A batch scheduler with high level components

In this article we present the design choices and the evaluation of a batch scheduler for large clusters, named OAR. This batch scheduler is based upon an original design that emphasizes on low software complexity by using high level tools. The global architecture is built upon the scripting language Perl and the relational database engine Mysql. The goal of the project OAR is to prove that it is possible today to build a complex system for ressource management using such tools without sacrificing efficiency and scalability. Currently, our system offers most of the important features implemented by other batch schedulers such as priority scheduling (by queues), reservations, backfilling and some global computing support. Despite the use of high level tools, our experiments show that our system has performances close to other systems. Furthermore, OAR is currently exploited for the management of 700 nodes (a metropolitan GRID) and has shown good efficiency and robustness

Expériences autour d'une nouvelle approche de conception d'un gestionnaire de travaux pour grappe

Dans cet article nous présentons les choix de conception et l'évaluation d'un gestionnaire de travaux pour grappe de grande taille, baptisé OAR. Ce gestionnaire repose sur une conception originale qui réduit la complexité logicielle, permet une extension aisée ainsi qu'une bonne réponse au problème du passage à l'échelle. %se distingue sur plusieurs points dont le passage à l'échelle, une faible complexité logicielle etc surtout une capacité d'extension aisée. L'architecture globale repose principalement sur deux composants de haut niveau~: un outil générique d'administration d'application (lancement, déploiement) passant à l'échelle et l'utilisation d'une base de données comme seul médium d'échange d'information entre les modules internes. Dans l'évaluation nous montrons à la fois le bon niveau de performance du système et sa capacité d'extension dans une utilisation de type Global Computing (utilisation des ressources inutilisées)

A batch scheduler with high level components

International audienceIn this article we present the design choices and the evaluation of a batch scheduler for large clusters, named OAR. This batch scheduler is based upon an original design that emphasizes on low software complexity by using high level tools. The global architecture is built upon the scripting language Perl and the relational database engine Mysql. The goal of the project OAR is to prove that it is possible today to build a complex system for ressource management using such tools without sacrificing efficiency and scalability. Currently, our system offers most of the important features implemented by other batch schedulers such as priority scheduling (by queues), reservations, backfilling and some global computing support. Despite the use of high level tools, our experiments show that our system has performances close to other systems. Furthermore, OAR is currently exploited for the management of 700 nodes (a metropolitan GRID) and has shown good efficiency and robustness

RMN des petites vésicules unilamellaires lipidiques (SUV) : une approche adaptée à l'étude des interactions périphériques membranaires

RENNES1-BU Santé (352382103) / SudocSudocFranceF

RMN 1H de stérols en association avec des petites vésicules lipidiques (SUV): rôle de la mobilité.

Poste

Interaction de porphyrines et dérivés porphyriniques avec des SUVs : détection et visibilité en RMN

Communication oral