Concentration of osmoregulated periplasmic glucans (OPGs) modulates the activation level of the RcsCD RcsB phosphorelay in the phytopathogen bacteria Dickeya dadantii

International audienceOsmoregulated periplasmic glucans (OPGs) are general constituents of many Proteobacteria. Synthesis of these oligosaccharides is repressed by increased osmolarity of the medium. OPGs are important factors required for full virulence in many zoo-or phytopathogens including Dickeya dadantii. The phytopathogen enterobacterium D. dadantii causes soft-rot disease on a wide range of plant species. The total loss of virulence of opg-negative strains of D. dadantii is linked to the constitutive activation of the RcsCD RcsB phosphorelay highlighting relationship between this phosphorelay and OPGs. Here we show that OPGs control the RcsCD RcsB activation in a concentration-dependent manner, are required for proper activation of this phosphorelay by medium osmolarity, and a high concentration of OPGs in planta is maintained to achieve the low level of activation of the RcsCD RcsB phosphorelay required for full virulence in D. dadantii

Perspectives économiques 2019-2021 Présentation générale

 Après un pic de croissance en 2017, l'activité économique mondiale donne des signes d'essoufflement. Nous anticipons que l'activité progresserait de 1,7 % dans les pays industrialisés et de 3,7 % dans les pays émergents contre 2,2 % et 4,2 % respectivement en 2018. La croissance mondiale se stabiliserait à 2,8 % puis 2,9 % en 2020 et 2021.  Dans le cas d'un Brexit sans accord, nous anticipons une récession de -1,1 % dès 2020 au Royaume-Uni. L'effet sur la croissance française serait modéré, avec une croissance annuelle amputée de 0,2 point la première année.  Pour la France, après une année de forte croissance (2,4 % en 2017), l'année 2018 a été marquée par un franc ralentissement (1,7 %). La croissance française, en glissement annuel, est ainsi passée en l'espace d'un an de 3 % à la fin 2017 à 1,2 % fin 2018.  Cependant, malgré le ralentissement de nos principaux partenaires commerciaux, Allemagne en tête, l'activité française résisterait en 2019 à 1,3 %, poussée par les mesures fiscales à destination des ménages, affichant pour la première fois depuis six ans une croissance supérieure à la moyenne de la zone euro hors France.  En 2020, tirée par une demande interne relativement dynamique grâce à une politique budgétaire encore en soutien, l'économie française maintiendrait un rythme de croissance de 1,3 %. En 2021, l'effort de consolidation budgétaire attendu conduirait la croissance française à revenir à son rythme potentiel de 1,2 %.  En 2019, soutenue par les mesures socio-fiscales (12 milliards, soit 0,9 point de RDB), le pouvoir d'achat des ménages augmenterait fortement (+2,4 %), sa plus forte hausse depuis 2007.  Cette nette amélioration du pouvoir d'achat n'a pas eu pour le moment les effets escomptés sur la consommation des ménages du fait d'une hausse du taux d'épargne qui s'apparente à une épargne de précaution, autre que celle liée au chômage.  Le taux de chômage passerait de 8,5 % actuellement à 8,3 % fin 2019, 8,2 % fin 2020 et 8,0 % fin 2021.  La trajectoire économique française se ferait au détriment du respect des règles budgétaires du Pacte de stabilité et de croissance, avec une réduction du déficit public structurel rapporté au PIB inférieure aux préconisations des traités européens. La dette publique, quant à elle, serait de 98,9 % du PIB en 2019 et 2020 (après 98,4 % en 2018), avant d'amorcer un début de réduction en 2021, année où elle atteindrait 98,5 % du PIB

Impact of CD4 and CD8 dynamics and viral rebounds on loss of virological control in HIV controllers

Objective: HIV controllers (HICs) spontaneously maintain HIV viral replication at low level without antiretroviral therapy (ART), a small number of whom will eventually lose this ability to control HIV viremia. The objective was to identify factors associated with loss of virological control. Methods: HICs were identified in COHERE on the basis of \ue2\u89\ua55 consecutive viral loads (VL) \ue2\u89\ua4500 copies/mL over \ue2\u89\ua51 year whilst ART-naive, with the last VL \ue2\u89\ua4500 copies/mL measured \ue2\u89\ua55 years after HIV diagnosis. Loss of virological control was defined as 2 consecutive VL >2000 copies/mL. Duration of HIV control was described using cumulative incidence method, considering loss of virological control, ART initiation and death during virological control as competing outcomes. Factors associated with loss of virological control were identified using Cox models. CD4 and CD8 dynamics were described using mixed-effect linear models. Results: We identified 1067 HICs; 86 lost virological control, 293 initiated ART, and 13 died during virological control. Six years after confirmation of HIC status, the probability of losing virological control, initiating ART and dying were 13%, 37%, and 2%. Current lower CD4/CD8 ratio and a history of transient viral rebounds were associated with an increased risk of losing virological control. CD4 declined and CD8 increased before loss of virological control, and before viral rebounds. Discussion: Expansion of CD8 and decline of CD4 during HIV control may result from repeated low-level viremia. Our findings suggest that in addition to superinfection, other mechanisms, such as low grade viral replication, can lead to loss of virological control in HICs

Challenges in Superconducting Accelerating Module Design and Construction for High Power Proton Accelerators

International audienceCEA is engaged in the construction of the IFMIF, SARAF and ESS superconducting linacs and in particular in the design and production of a their accelerating cryomodules: 1 low-beta half-wave 176 MHz resonators for IFMIF, 4 low-beta half-wave 176 MHz resonators for SARAF and 30 medium and high-beta elliptical cavity resonators for ESS. The developments of these RF cryomodules, although at various stages, are led in parallel by the cryomodule team at CEA-Saclay, including all RF, mechanical, thermal, cryogenic, integration and QA-QC aspects in a global approach which attempts to optimise synergies and lessons learnt between these projects. A status report will be presented describing the common approaches and methods, and the systemic particularities of each project

Determination of chlorine dioxide, chlorite and chlorate by indigo carmine methods in natural waters: Study of interferences [Determination en milieu naturel du dioxyde de chlore, des ions chlorite et chlorate basee sur l'utilisation du carmin indigo: Etude des interferences]

National audienceOver the last decade, chlorine dioxide has been increasingly used for disinfecting drinking water in many countries. A guarantee for the protection of the consumer is the presence of a sufficient residual concentration of the bactericidal reagent in drinking water. Thus it is important to determine exactly and accurately the levels of chlorine dioxide at the tap. During water treatment and subsequent distribution, chlorine dioxide can undergo a variety of reduction and disproportionation reactions producing primarily chloride but also chlorite and chlorate, which have been shown to cause haemolytic anemia. Reliable analytical methods are needed to identify and determine levels of chlorine dioxide, chlorite and chlorate in drinking water. A procedure based on the use of indigo carmine for the determination of each species in natural waters is suggested in this paper. In phosphate buffer (pH 6.8), two moles of chlorine dioxide oxidize one mole of indigo carmine. The concentration of the bactericidal reagent can be determined by measuring the difference in absorbance of the dye at 610 nm before and after reaction with chlorine dioxide. This method is selective as chlorite and chlorate do not react with indigo carmine in phosphate buffer at pH 6.8. Although the spectrophotometric method can be used successfully used at levels of chlorine dioxide down to 30 μg/l, the determination of lower levels in tap water requires a more sensitive method such as an electrochemical stripping procedure. This analysis is based on the measurement of the decrease in the indigo carmine signal after addition of chlorine dioxide. The detection limit is around 1 μg/l. At pH = 2, one mole of indigo carmine reduces one mole of chlorite. Thus the chlorite concentration can be determined by measuring the indigo carmine absorbance at pH = 2. At pH = 0, indigo carmine reacts with both chlorite and chlorate. A measurement at pH = 0 allows chlorate concentrations to be determined since the decrease in absorbance due to the presence of chlorite can be calculated. The stability of indigo carmine absorbance has been studied. An indigo carmine solution prepared in phosphate buffer is stable over several days if kept in light-proof bottles. It is not surprising that the presence of chlorite and chlorate does not lead to a change in absorbance as they do not react with the dye at pH = 6.8. A slight decrease in absorbance of an indigo carmine solution containing chlorine dioxide is observed after about twenty hours. This means that the chlorine dioxide concentration has to be determined in the first hours, which follow the addition of the dye to the sample in order to avoid errors. Interferences can arise from other residual oxidants, which may also be used in water treatment, or from substances present in the sample, which may react with indigo carmine, chlorite and chlorate. Accordingly, we have considered the influence of humic substances, ozone and hypochlorite. The absorbance of indigo carmine at pH = 2 and at pH = 0 does not change in presence of natural organic matter (1 mg/l). Chlorite and chlorate react with humic substances but the kinetics are much slower than those of the reactions with indigo carmine. Errors arising from humic substances in chlorite and chlorate measurements are thus very weak. Ozone may interfere in analyses as it reacts with indigo carmine. However its existence in the distribution network is unlikely as it also reacts with chlorine dioxide, which is in excess, and chlorite to give chlorate. Hypochlorite causes errors in chlorine dioxide, chlorite and chlorate determinations as a result of a reaction with indigo carmine. In the case of chlorine dioxide determinations, errors can be eliminated by adding ammonia to the sample before indigo carmine. Once the validity of the procedures had been proven in synthetic media, the methods were applied to a natural water, that of the water distribution network of the city of Brest, France. The results have been compared with those of other analytical techniques.A procedure based on the use of indigo carmine for the determination of each species in natural waters is presented. The method is selective as chlorite and chlorate do not react with indigo carmine in phosphate buffer at pH 6.8. Results obtained with this procedure are compared with those of other analytical techniques

Determination of the trace of aluminium (III) in natural fresh water by cathodic redissolution following the adsorption of an aluminium-lumogallion complex [Determination de traces d'aluminium (III) dans les eaux douces naturelles par redissolution cathodique apres adsorption d'un complexe aluminium-lumogallion]

National audienceThis paper describes an electrochemical procedure for the determination of aluminium traces in which pre-concentration is achieved by the adsorption of an aluminium-lumogallion complex onto a hanging mercury drop electrode. The effects of various operational parameters (pH, ligand concentration, potential and accumulation time) on the reduction current of the adsorbed chelate are discussed. Possible interferences by trace metals and organic matter are investigated. A linear current concentration relationship was observed up to 1.5 10-7 mol.L-1. The detection limit is 1.5 10-9 mol.L-1

Determination of chlorine dioxide, chlorite and chlorate by indigo carmine methods in natural waters: Study of interferences [Determination en milieu naturel du dioxyde de chlore, des ions chlorite et chlorate basee sur l'utilisation du carmin indigo: Etude des interferences]

National audienceOver the last decade, chlorine dioxide has been increasingly used for disinfecting drinking water in many countries. A guarantee for the protection of the consumer is the presence of a sufficient residual concentration of the bactericidal reagent in drinking water. Thus it is important to determine exactly and accurately the levels of chlorine dioxide at the tap. During water treatment and subsequent distribution, chlorine dioxide can undergo a variety of reduction and disproportionation reactions producing primarily chloride but also chlorite and chlorate, which have been shown to cause haemolytic anemia. Reliable analytical methods are needed to identify and determine levels of chlorine dioxide, chlorite and chlorate in drinking water. A procedure based on the use of indigo carmine for the determination of each species in natural waters is suggested in this paper. In phosphate buffer (pH 6.8), two moles of chlorine dioxide oxidize one mole of indigo carmine. The concentration of the bactericidal reagent can be determined by measuring the difference in absorbance of the dye at 610 nm before and after reaction with chlorine dioxide. This method is selective as chlorite and chlorate do not react with indigo carmine in phosphate buffer at pH 6.8. Although the spectrophotometric method can be used successfully used at levels of chlorine dioxide down to 30 μg/l, the determination of lower levels in tap water requires a more sensitive method such as an electrochemical stripping procedure. This analysis is based on the measurement of the decrease in the indigo carmine signal after addition of chlorine dioxide. The detection limit is around 1 μg/l. At pH = 2, one mole of indigo carmine reduces one mole of chlorite. Thus the chlorite concentration can be determined by measuring the indigo carmine absorbance at pH = 2. At pH = 0, indigo carmine reacts with both chlorite and chlorate. A measurement at pH = 0 allows chlorate concentrations to be determined since the decrease in absorbance due to the presence of chlorite can be calculated. The stability of indigo carmine absorbance has been studied. An indigo carmine solution prepared in phosphate buffer is stable over several days if kept in light-proof bottles. It is not surprising that the presence of chlorite and chlorate does not lead to a change in absorbance as they do not react with the dye at pH = 6.8. A slight decrease in absorbance of an indigo carmine solution containing chlorine dioxide is observed after about twenty hours. This means that the chlorine dioxide concentration has to be determined in the first hours, which follow the addition of the dye to the sample in order to avoid errors. Interferences can arise from other residual oxidants, which may also be used in water treatment, or from substances present in the sample, which may react with indigo carmine, chlorite and chlorate. Accordingly, we have considered the influence of humic substances, ozone and hypochlorite. The absorbance of indigo carmine at pH = 2 and at pH = 0 does not change in presence of natural organic matter (1 mg/l). Chlorite and chlorate react with humic substances but the kinetics are much slower than those of the reactions with indigo carmine. Errors arising from humic substances in chlorite and chlorate measurements are thus very weak. Ozone may interfere in analyses as it reacts with indigo carmine. However its existence in the distribution network is unlikely as it also reacts with chlorine dioxide, which is in excess, and chlorite to give chlorate. Hypochlorite causes errors in chlorine dioxide, chlorite and chlorate determinations as a result of a reaction with indigo carmine. In the case of chlorine dioxide determinations, errors can be eliminated by adding ammonia to the sample before indigo carmine. Once the validity of the procedures had been proven in synthetic media, the methods were applied to a natural water, that of the water distribution network of the city of Brest, France. The results have been compared with those of other analytical techniques.A procedure based on the use of indigo carmine for the determination of each species in natural waters is presented. The method is selective as chlorite and chlorate do not react with indigo carmine in phosphate buffer at pH 6.8. Results obtained with this procedure are compared with those of other analytical techniques

Determination of the trace of aluminium (III) in natural fresh water by cathodic redissolution following the adsorption of an aluminium-lumogallion complex [Determination de traces d'aluminium (III) dans les eaux douces naturelles par redissolution cathodique apres adsorption d'un complexe aluminium-lumogallion]

National audienceThis paper describes an electrochemical procedure for the determination of aluminium traces in which pre-concentration is achieved by the adsorption of an aluminium-lumogallion complex onto a hanging mercury drop electrode. The effects of various operational parameters (pH, ligand concentration, potential and accumulation time) on the reduction current of the adsorbed chelate are discussed. Possible interferences by trace metals and organic matter are investigated. A linear current concentration relationship was observed up to 1.5 10-7 mol.L-1. The detection limit is 1.5 10-9 mol.L-1

Sb(III) oxidation by iodate in seawater : a cautionary tale

International audienceKnowledge of antimony redox kinetics is crucial in understanding the impact and fate of antimony in the environment. The oxidation of Sb(III) with iodate was measured in 0.5 mol L1 NaCl solutions as a function of pH at environmentally significant concentrations of antimony and iodate. The oxidation of Sb(III) with iodate is pH dependent: no measurable oxidation is observed below pH 9. The undissociated Sb(OH)3 does not react with iodate and the formation of significant amounts of Sb(OH)4 is needed for the reaction to take place. It is thus unlikely that iodate oxidizes Sb(III) in seawater. Our results support that the observed presence of the thermodynamically unstable Sb(III) in oxic waters can be due to the kinetic stabilization of the trivalent state vis-a`-vis some common abiotic oxidants at natural pH values. However, caution must be exercised because the presence of iodate in seawater favours fast oxidation of Sb(III) if water samples are acidified, as is the case in many analytical procedures