Rotating disk electrodes to assess river biofilm thickness and elasticity

The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s−1 in inflow and constricted sections respectively) and containing 24 RDE was immersed in the river for 21 days. Biofilm thickness and elasticity were quantified using an electrochemical assay on 7 and 21 days old RDE-grown biofilms (t7 and t21, respectively). Biofilm thickness was affected by colonisation length and flow conditions and ranged from 36 ± 15 μm (mean ± standard deviation, n = 6) in the fast flow section at t7 to 340 ± 140 μm (n = 3) in the slow flow section at t21. Comparing the electrochemical signal to stereomicroscopic estimates of biofilms thickness indicated that the method consistently allowed (i) to detect early biofilm colonisation in the river and (ii) to measure biofilm thickness of up to a few hundred μm. Biofilm elasticity, i.e. biofilm squeeze by hydrodynamic constraint, was significantly higher in the slow (1300 ± 480 μm rpm1/2, n = 8) than in the fast flow sections (790 ± 350 μm rpm1/2, n = 11). Diatom and bacterial density, and biofilm-covered RDE surface analyses (i) confirmed that microbial accrual resulted in biofilm formation on the RDE surface, and (ii) indicated that thickness and elasticity represent useful integrative parameters of biofilm architecture that could be measured on natural river assemblages using the proposed electrochemical method

Ageing of reverse osmosis membranes under gamma irradiation

Reverse osmosis (RO) shows a real growth among the water and wastewater treatment processes available (evaporation, ions exchange, electrodialysis) since forty years. RO has become the most used processes for desalination of seawater or saline water. Following Fukushima-Daiichi accident, RO has been chosen as the final treatment of the seawater used to cool the damaged nuclear reactors. Only very few studies and data has been published about RO applied to radioactive wastewater. Currently RO membranes are made of polymers that are sensitive to irradiation and could be strongly damaged due to these ionizing radiations. Data about the ageing of the membranes under these operating conditions are very difficult to obtain even if RO seems to be efficient in the process used in Fukushima. Please click Additional Files below to see the full abstract

Molecular characterization of measles virus strains causing subactute sclerosing panencephalitis in France in 1977 and 2007: Molecular analysis of SSPE strains in France

International audienceMeasles virus strains from two subacute sclerosing panencephalitis (SSPE) cases diagnosed in 1977 (Laine strain) and in 2007 (Hoedts strain) were studied. Phylogenetic analysis based on C-terminal part of the nucleoprotein and the entire H gene showed that Hoedts strain, circulating in France presumably in the 1980s, belonged to genotype C2. However, Laine strain, suspected to have circulated between 1940s and 1960s, could not be assigned to any known measles virus genotypes. Sequences analysis of the Laine strain suggested that it originated from a measles virus that may have circulating at the same period as the Edmonston strain. The analysis of the whole genome of both SSPE strains revealed biased hypermutations in M, F and H gene. Some of these mutations like the L165P found in the M protein sequence of the Laine strain, the amino acid position 94, where a mutation M94V was found in the F protein sequence of the Hoedts strain are known to play an important role in the glycoprotein interaction and to impair the ability of measles virus strain to produce cell-free infectious viral particles.This is the first study on molecular characterization of the entire coding region of measles virus isolated from SSPE cases in France

Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof

Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water

The Tara Pacific expedition—A pan-ecosystemic approach of the “-omics” complexity of coral reef holobionts across the Pacific Ocean

Coral reefs are the most diverse habitats in the marine realm. Their productivity, structural complexity, and biodiversity critically depend on ecosystem services provided by corals that are threatened because of climate change effects—in particular, ocean warming and acidification. The coral holobiont is composed of the coral animal host, endosymbiotic dinoflagellates, associated viruses, bacteria, and other microeukaryotes. In particular, the mandatory photosymbiosis with microalgae of the family Symbiodiniaceae and its consequences on the evolution, physiology, and stress resilience of the coral holobiont have yet to be fully elucidated. The functioning of the holobiont as a whole is largely unknown, although bacteria and viruses are presumed to play roles in metabolic interactions, immunity, and stress tolerance. In the context of climate change and anthropogenic threats on coral reef ecosystems, the Tara Pacific project aims to provide a baseline of the “-omics” complexity of the coral holobiont and its ecosystem across the Pacific Ocean and for various oceanographically distinct defined areas. Inspired by the previous Tara Oceans expeditions, the Tara Pacific expedition (2016–2018) has applied a pan-ecosystemic approach on coral reefs throughout the Pacific Ocean, drawing an east–west transect from Panama to Papua New Guinea and a south–north transect from Australia to Japan, sampling corals throughout 32 island systems with local replicates. Tara Pacific has developed and applied state-of-the-art technologies in very-high-throughput genetic sequencing and molecular analysis to reveal the entire microbial and chemical diversity as well as functional traits associated with coral holobionts, together with various measures on environmental forcing. This ambitious project aims at revealing a massive amount of novel biodiversity, shedding light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs and providing a reference of the biological state of modern coral reefs in the Anthropocene

The BLLAST field experiment: Boundary-Layer late afternoon and sunset turbulence

Due to the major role of the sun in heating the earth's surface, the atmospheric planetary boundary layer over land is inherently marked by a diurnal cycle. The afternoon transition, the period of the day that connects the daytime dry convective boundary layer to the night-time stable boundary layer, still has a number of unanswered scientific questions. This phase of the diurnal cycle is challenging from both modelling and observational perspectives: it is transitory, most of the forcings are small or null and the turbulence regime changes from fully convective, close to homogeneous and isotropic, toward a more heterogeneous and intermittent state. These issues motivated the BLLAST (Boundary-Layer Late Afternoon and Sunset Turbulence) field campaign that was conducted from 14 June to 8 July 2011 in southern France, in an area of complex and heterogeneous terrain. A wide range of instrumented platforms including full-size aircraft, remotely piloted aircraft systems, remote-sensing instruments, radiosoundings, tethered balloons, surface flux stations and various meteorological towers were deployed over different surface types. The boundary layer, from the earth's surface to the free troposphere, was probed during the entire day, with a focus and intense observation periods that were conducted from midday until sunset. The BLLAST field campaign also provided an opportunity to test innovative measurement systems, such as new miniaturized sensors, and a new technique for frequent radiosoundings of the low troposphere. Twelve fair weather days displaying various meteorological conditions were extensively documented during the field experiment. The boundary-layer growth varied from one day to another depending on many contributions including stability, advection, subsidence, the state of the previous day's residual layer, as well as local, meso- or synoptic scale conditions. Ground-based measurements combined with tethered-balloon and airborne observations captured the turbulence decay from the surface throughout the whole boundary layer and documented the evolution of the turbulence characteristic length scales during the transition period. Closely integrated with the field experiment, numerical studies are now underway with a complete hierarchy of models to support the data interpretation and improve the model representations.publishedVersio

Diversity-oriented synthesis of pochonins: a privilege scaffold for ATPase and kinase inhibition

Les pochonines A-F sont six molécules récemment décrites appartenant à la famille des lactones résorcyliques à 14 chaînons et qui présentent une activité contre le virus de l’herpès. Notre intérêt initial pour ces dérivés était fondé sur l’observation que plusieurs autres lactones résorcyliques sont connues pour leur potentiel biologique comme inhibiteurs de kinases ou d’ATPases. Par ailleurs le radicicol, de structure proche, est un puissant inhibiteur de la protéine de choc thermique HSP90, cible privilégiée pour la chimiothérapie en raison de son rôle fondamental dans la maturation fonctionnelle de nombreux oncogènes. Une synthèse de la pochonine C et sa conversion en radicicol ont été réalisées en respectivement sept et huit étapes, à partir de trois fragments facilement accessibles. Des synthèses alternatives de ces composés ont également été réalisées en utilisant des réactifs supportés et des réactions sur phase solide. A partir d’une analyse théorique de la dynamique moléculaire du radicicol et de ses analogues connus, une corrélation entre l’inhibition de HSP90 et l’énergie libre du conformère bioactif a été établie, permettant ainsi l’identification de la pochonine D comme inhibiteur potentiel de cette protéine. La synthèse totale de la pochonine D en utilisant des réactifs supportés a permis de confirmer cette hypothèse et de montrer que celle-ci est quasiment aussi active contre HSP90 que le radicicol (IC50 (radicicol) = 20 nM, IC50 (pochonine D) = 80 nM). Considérant les similarités structurales entre les pochonines D et A, nous avons également synthétisé la pochonine A pour son évaluation en tant qu’inhibiteur de HSP90, celle-ci présentant effectivement une activité de l’ordre du nanomolaire. La chimie développée à l’aide de réactifs supportés pour la synthèse des pochonines naturelles (A et D en particulier) nous a ensuite permis de préparer une banque de molécules fondée sur le même squelette et présentant cinq points de diversité, de manière à étudier les relations structure-activité sur différentes cibles. L’évaluation biologique de cette bibliothèque de 100 molécules pour l’inhibition d’un panel de 24 kinases et de HSP90 a révélé plusieurs composés actifs et sélectifs, démontrant ainsi le potentiel de la famille des lactones résorcyliques pour l’inhibition de kinases et d’ATPases.Pochonins A − F are six new members of the 14-membered resorcylic acid lactones (RALs) family which were identified in a Herpes Simplex Virus replication assay. Our interest in the pochonins stems from the observation that several other RALs are known to inhibit ATPases or kinases. Among them, radicicol was shown to be a potent inhibitor of HSP90 (Heat Shock Protein 90) whose activity is required for the functional maturation of a number of oncogenes, thus making this protein an attractive target for chemotherapy. A modular synthesis of pochonin C and its conversion to radicicol is presented. Both natural products are prepared in seven and eight steps, respectively, from three readily available fragments. Alternative syntheses of these compounds were also achieved using a combination of polymer-bound reagents and reactions on solid phase. Based on a molecular dynamics/minimization of radicicol and several known analogs, a correlation between the HSP90-inhibitory activity and the free energy of the bioactive conformer was established, leading to the identification of pochonin D as a potential inhibitor of HSP90. Its synthesis using polymer-bound reagents allowed us to confirm this finding and pochonin D was shown to be nearly as potent an HSP90 inhibitor as radicicol. Considering their closely-related structure, pochonin A was also synthesized and tested for HSP90 inhibition. The polymer-assisted chemistry developed for the pochonins syntheses enabled us to prepare a library based on the pochonin scaffold bearing five points of diversity, allowing us to extend beyond the modifications of the natural resorcylic acid lactones. Testing the library for its inhibition against a panel of 24 kinases at 10 µM and against HSP90 reveals several hits, thereby demonstrating the potential of the resorcylides towards the inhibition of therapeutically relevant kinases and ATPases. These syntheses of the pochonins were also the first reported in the literature allowing us to confirm structural assignments and to provide optical rotations as well as to define the stereochemistry of pochonin C’s carbon bearing the chlorine atom

Les pochonines,une structure privilégie pour l'inhibition de kinases et d'ATPases

Les pochonines A-F sont six molécules récemment décrites appartenant à la famille des lactones résorcyliques à 14 chaînons et qui présentent une activité contre le virus de l'herpès. Notre intérêt initial pour ces dérivés était fondé sur l'observation que plusieurs autres lactones résorcyliques sont connues pour leur potentiel biologique comme inhibiteurs de kinases ou d'ATPases. Par ailleurs le radicicol, de structure proche, est un puissant inhibiteur de la protéine de choc thermique HSP90, cible privilégiée pour la chimiothérapie en raison de son rôle fondamental dans la maturation fonctionnelle de nombreux oncogènes. Une synthèse de la pochonine C et sa conversion en radicicol ont été réalisées en respectivement sept et huit étapes, à partir de trois fragments facilement accessibles. Des synthèses alternatives de ces composés ont également été réalisées en utilisant des réactifs supportés et des réactions sur phase solide. A partir d'une analyse théorique de la dynamique moléculaire du radicicol et de ses analogues connus, une corrélation entre l'inhibition de HSP90 et l'énergie libre du conformère bioactif a été établie, permettant ainsi l'identification de la pochonine D comme inhibiteur potentiel de cette protéine. La synthèse totale de la pochonine D en utilisant des réactifs supportés a permis de confirmer cette hypothèse et de montrer que celle-ci est quasiment aussi active contre HSP90 que le radicicol (IC50 (radicicol) = 20 nM, IC50 (pochonine D) = 80 nM). Considérant les similarités structurales entre les pochonines D et A, nous avons également synthétisé la pochonine A pour son évaluation en tant qu inhibiteur de HSP90, celle-ci présentant effectivement une activité de l'ordre du nanomolaire. La chimie développée à l'aide de réactifs supportés pour la synthèse des pochonines naturelles (A et D en particulier) nous a ensuite permis de préparer une banque de molécules fondée sur le même squelette et présentant cinq points de diversité, de manière à étudier les relations structure-activité sur différentes cibles. L'évaluation biologique de cette bibliothèque de 100 molécules pour l'inhibition d'un panel de 24 kinases et de HSP90 a révélé plusieurs composés actifs et sélectifs, démontrant ainsi le potentiel de la famille des lactones résorcyliques pour l'inhibition de kinases et d'ATPases.Pochonins A F are six new members of the 14-membered resorcylic acid lactones (RALs) family which were identified in a Herpes Simplex Virus replication assay. Our interest in the pochonins stems from the observation that several other RALs are known to inhibit ATPases or kinases. Among them, radicicol was shown to be a potent inhibitor of HSP90 (Heat Shock Protein 90) whose activity is required for the functional maturation of a number of oncogenes, thus making this protein an attractive target for chemotherapy. A modular synthesis of pochonin C and its conversion to radicicol is presented. Both natural products are prepared in seven and eight steps, respectively, from three readily available fragments. Alternative syntheses of these compounds were also achieved using a combination of polymer-bound reagents and reactions on solid phase. Based on a molecular dynamics/minimization of radicicol and several known analogs, a correlation between the HSP90-inhibitory activity and the fre energy of the bioactive conformer was established, leading to the identification of pochonin D as a potential inhibitor of HSP90. Its synthesis using polymer-bound reagents allowed us to confirm this finding and pochonin D was shown to be nearly as potent an HSP90 inhibitor as radicicol. Considering their closely-related structure, pochonin A was also synthesized and tested for HSP90 inhibition. The polymer-assisted chemistry developed for the pochonins syntheses enabled us to prepare a library based on the pochonin scaffold bearing five points of diversity, allowing us to extend beyond the modifications of the natural resorcylic acid lactones. Testing the library for its inhibition against a panel of 24 kinases at 10 M and against HSP90 reveals several hits, thereby demonstrating the potential of the resorcylides towards the inhibition of therapeutically relevant kinases and ATPases. These syntheses of the pochonins were also the first reported in the literature allowing us to confirm structural assignments and to provide optical rotations as well as to define the stereochemistry of pochonin C s carbon bearing the chlorine atom

Les pochonines,une structure privilégie pour l'inhibition de kinases et d'ATPases

Les pochonines A-F sont six molécules récemment décrites appartenant à la famille des lactones résorcyliques à 14 chaînons et qui présentent une activité contre le virus de l'herpès. Notre intérêt initial pour ces dérivés était fondé sur l'observation que plusieurs autres lactones résorcyliques sont connues pour leur potentiel biologique comme inhibiteurs de kinases ou d'ATPases. Par ailleurs le radicicol, de structure proche, est un puissant inhibiteur de la protéine de choc thermique HSP90, cible privilégiée pour la chimiothérapie en raison de son rôle fondamental dans la maturation fonctionnelle de nombreux oncogènes. Une synthèse de la pochonine C et sa conversion en radicicol ont été réalisées en respectivement sept et huit étapes, à partir de trois fragments facilement accessibles. Des synthèses alternatives de ces composés ont également été réalisées en utilisant des réactifs supportés et des réactions sur phase solide. A partir d'une analyse théorique de la dynamique moléculaire du radicicol et de ses analogues connus, une corrélation entre l'inhibition de HSP90 et l'énergie libre du conformère bioactif a été établie, permettant ainsi l'identification de la pochonine D comme inhibiteur potentiel de cette protéine. La synthèse totale de la pochonine D en utilisant des réactifs supportés a permis de confirmer cette hypothèse et de montrer que celle-ci est quasiment aussi active contre HSP90 que le radicicol (IC50 (radicicol) = 20 nM, IC50 (pochonine D) = 80 nM). Considérant les similarités structurales entre les pochonines D et A, nous avons également synthétisé la pochonine A pour son évaluation en tant qu inhibiteur de HSP90, celle-ci présentant effectivement une activité de l'ordre du nanomolaire. La chimie développée à l'aide de réactifs supportés pour la synthèse des pochonines naturelles (A et D en particulier) nous a ensuite permis de préparer une banque de molécules fondée sur le même squelette et présentant cinq points de diversité, de manière à étudier les relations structure-activité sur différentes cibles. L'évaluation biologique de cette bibliothèque de 100 molécules pour l'inhibition d'un panel de 24 kinases et de HSP90 a révélé plusieurs composés actifs et sélectifs, démontrant ainsi le potentiel de la famille des lactones résorcyliques pour l'inhibition de kinases et d'ATPases.Pochonins A F are six new members of the 14-membered resorcylic acid lactones (RALs) family which were identified in a Herpes Simplex Virus replication assay. Our interest in the pochonins stems from the observation that several other RALs are known to inhibit ATPases or kinases. Among them, radicicol was shown to be a potent inhibitor of HSP90 (Heat Shock Protein 90) whose activity is required for the functional maturation of a number of oncogenes, thus making this protein an attractive target for chemotherapy. A modular synthesis of pochonin C and its conversion to radicicol is presented. Both natural products are prepared in seven and eight steps, respectively, from three readily available fragments. Alternative syntheses of these compounds were also achieved using a combination of polymer-bound reagents and reactions on solid phase. Based on a molecular dynamics/minimization of radicicol and several known analogs, a correlation between the HSP90-inhibitory activity and the fre energy of the bioactive conformer was established, leading to the identification of pochonin D as a potential inhibitor of HSP90. Its synthesis using polymer-bound reagents allowed us to confirm this finding and pochonin D was shown to be nearly as potent an HSP90 inhibitor as radicicol. Considering their closely-related structure, pochonin A was also synthesized and tested for HSP90 inhibition. The polymer-assisted chemistry developed for the pochonins syntheses enabled us to prepare a library based on the pochonin scaffold bearing five points of diversity, allowing us to extend beyond the modifications of the natural resorcylic acid lactones. Testing the library for its inhibition against a panel of 24 kinases at 10 M and against HSP90 reveals several hits, thereby demonstrating the potential of the resorcylides towards the inhibition of therapeutically relevant kinases and ATPases. These syntheses of the pochonins were also the first reported in the literature allowing us to confirm structural assignments and to provide optical rotations as well as to define the stereochemistry of pochonin C s carbon bearing the chlorine atom