Xenopus Meiotic Microtubule-Associated Interactome

In metazoan oocytes the assembly of a microtubule-based spindle depends on the activity of a large number of accessory non-tubulin proteins, many of which remain unknown. In this work we isolated the microtubule-bound proteins from Xenopus eggs. Using mass spectrometry we identified 318 proteins, only 43 of which are known to bind microtubules. To integrate our results, we compiled for the first time a network of the meiotic microtubule-related interactome. The map reveals numerous interactions between spindle microtubules and the newly identified non-tubulin spindle components and highlights proteins absent from the mitotic spindle proteome. To validate newly identified spindle components, we expressed as GFP-fusions nine proteins identified by us and for first time demonstrated that Mgc68500, Loc398535, Nif3l1bp1/THOC7, LSM14A/RAP55A, TSGA14/CEP41, Mgc80361 and Mgc81475 are associated with spindles in egg extracts or in somatic cells. Furthermore, we showed that transfection of HeLa cells with siRNAs, corresponding to the human orthologue of Mgc81475 dramatically perturbs spindle formation in HeLa cells. These results show that our approach to the identification of the Xenopus microtubule-associated proteome yielded bona fide factors with a role in spindle assembly

Itinéraire Méthodologique de Diagnostic Partagé des enjeux environnementaux. Comment accompagner le changement dans l'ingénierie territoriale d'Etat.

International audienc

Itinéraire Méthodologique de Diagnostic Partagé des enjeux environnementaux. Comment accompagner le changement dans l'ingénierie territoriale d'Etat.

International audienc

AN ALTERNATIVE SIMPLE APPROACH FOR THE MODELLING OF FUEL ASSEMBLIES WITH MISSING FUEL RODS

International audienceThis paper presents a discussion about an alternative calculation scheme that can be used to model nuclear fuel assemblies under water. In criticality Monte-Carlo multigroup calculations performed by French industrials, heterogeneous media (such as fuel assemblies or more generally any type of arrays of fissile material in water) are mostly modelled as a homogeneous medium whose nuclear cross sections are adjusted to match those of the original heterogeneous system. These cross sections are obtained using a preliminary flux calculation based on deterministic methods. For a fuel assembly, the simplest deterministic method is to consider a simple cell (fuel oxide cylinder surrounded by clad and water) with a moderation ratio determined by considering that the water around fuel rods and inside empty slots is homogeneously distributed all over the assembly section. This simplified calculation scheme, very useful for parametric studies and for modelling missing fuel rods which position is not known, allows fast multigroup calculations and only requires knowing the number of fuel rods in the section. However, in some cases, this simplified approach can lead to underestimate the assembly reactivity. Indeed, the moderation ratio is generally heterogeneous within the assembly section, particularly for boiling water reactor types assemblies for which empty slots are unequally dispatched within their section. Moreover, the modelling of the water located outside of the assembly section can lead to mis-estimate the moderation of the external fuel rods. The purpose of this paper is to present an alternative simple approach to use preliminary deterministic calculations to generate homogeneous cross sections for multigroup Monte Carlo codes, in order to avoid two dimensional deterministic calculations which limit the parametric studies possibilities and are computer-time consuming. This paper will firstly remind generalities about the problematics regarding missing fuel rods in fuel assembly modelling. Then, results obtained with the alternative calculation scheme will be presented, with an explanation of the discrepancies compared to other calculation schemes. At last, a discussion about the bounding trait of this alternative scheme and the parameters that can have an influence on its behaviour will be presented

La méthode de diagnostic partagé : comprendre et analyser un territoire avec les représentations spatiales schématiques pour produire le « Dire de l’État »

4 page de la mallette pédagogique d’analyse territoriale, DREAL Poitou-Charente

La méthode de diagnostic partagé : comprendre et analyser un territoire avec les représentations spatiales schématiques pour produire le « Dire de l’État »

4 page de la mallette pédagogique d’analyse territoriale, DREAL Poitou-Charente

Antibiotic and efflux: Combined spectrofluorimetry and mass spectrometry

International audienceBackgroundIn Gram-negative bacteria, passing through the double membrane barrier to reach the inhibitory concentration inside the bacterium is a pivotal step for antibiotic activity. Spectrofluorimetry has been developed to follow fluoroquinolone accumulation inside bacteria using intrinsic bacterial fluorescence as an internal standard. However, adaptation for non-fluorescent antibiotics is needed; quantitative methods based on MS offer the possibility of expanding the detection range obtained by spectrofluorimetry.ObjectivesTo validate, with spectrofluorimetry, the use of MS to measure antibiotic accumulation in cells and to determine the relationship between antibiotic concentrations and the amount of intrabacterial accumulation in different efflux backgrounds on the same batch of molecules.MethodsSpectrofluorimetry was performed in parallel with MS on the same samples to measure the ciprofloxacin and fleroxacin accumulation in cells expressing various efflux pump levels. A microplate protocol was set up to determine the antibiotic accumulation as a function of external antibiotic concentrations.ResultsA correlation existed between the data obtained with spectrofluorimetry and MS, whatever the efflux pump or tested antibiotic. The results highlighted different dynamics of uptake between ciprofloxacin and fleroxacin as well as the relationship between the level of efflux activity and antibiotic accumulation.ConclusionsWe have developed a microplate protocol and cross-validated two complementary methods: spectrofluorimetry, which contains a reliable internal standard; and MS, which allows detection of low antibiotic amounts. These assays allow study of the dose effect and the efflux impact on the intrabacterial accumulation of antibiotics

Case Report: Persistency Pneumococcal Polysaccharide in Cerebrospinal Fluid During a Post Pneumococcal Chronic Aseptic Meningitis: Coincidental or (Auto-)Inflammatory Embers

International audienceWe report the case of a 9-months-old boy that has presented a steroid-dependent post-pneumococcal chronic aseptic meningitis was associated with persistence of pneumococcal cell wall components in cerebrospinal fluid during more than 20 months. Suggesting that this antigenic persistence could be involved in post-infectious manifestations through innate immunity response