A New Highly Conserved Antibiotic Sensing/Resistance Pathway in Firmicutes Involves an ABC Transporter Interplaying with a Signal Transduction System

Signal transduction systems and ABC transporters often contribute jointly to adaptive bacterial responses to environmental changes. In Bacillus subtilis, three such pairs are involved in responses to antibiotics: BceRSAB, YvcPQRS and YxdJKLM. They are characterized by a histidine kinase belonging to the intramembrane sensing kinase family and by a translocator possessing an unusually large extracytoplasmic loop. It was established here using a phylogenomic approach that systems of this kind are specific but widespread in Firmicutes, where they originated. The present phylogenetic analyses brought to light a highly dynamic evolutionary history involving numerous horizontal gene transfers, duplications and lost events, leading to a great variety of Bce-like repertories in members of this bacterial phylum. Based on these phylogenetic analyses, it was proposed to subdivide the Bce-like modules into six well-defined subfamilies. Functional studies were performed on members of subfamily IV comprising BceRSAB from B. subtilis, the expression of which was found to require the signal transduction system as well as the ABC transporter itself. The present results suggest, for the members of this subfamily, the occurrence of interactions between one component of each partner, the kinase and the corresponding translocator. At functional and/or structural levels, bacitracin dependent expression of bceAB and bacitracin resistance processes require the presence of the BceB translocator loop. Some other members of subfamily IV were also found to participate in bacitracin resistance processes. Taken together our study suggests that this regulatory mechanism might constitute an important common antibiotic resistance mechanism in Firmicutes. [Supplemental material is available online at http://www.genome.org.

Design and development of immunomodulatory antigen delivery systems based on peptide/PEG-PLA conjugate for tuning immunity

[[abstract]]Cancer vaccines are considered to be a promising tool for cancer immunotherapy. However, a well-designed cancer vaccine should combine a tumor-associated antigen (TAA) with the most effective immunomodulatory agents and/or delivery system to provoke intense immune responses against the TAA. In the present study, we introduced a new approach by conjugating the immunomodulatory molecule LD-indolicidin to the hydrophilic chain end of the polymeric emulsifier poly(ethylene glycol)-polylactide (PEG-PLA), allowing the molecule to be located close to the surface of the resulting emulsion. A peptide/polymer conjugate, named LD-indolicidin-PEG-PLA, was synthesized by conjugation of the amine end-group of LD-indolicidin to the N-hydroxysuccinimide-activated carboxyl end-group of PEG. As an adjuvant for cancer immunotherapeutic use, TAA vaccine candidate formulated with the LD-indolicidin-PEG-PLA-stabilized squalene-in-water emulsion could effectively help to elicit a T helper (Th)1-dominant antigen-specific immune response as well as antitumor ability, using ovalbumin (OVA) protein/EG7 cells as a TAA/tumor cell model. Taken together, these results open up a new approach to the development of immunomodulatory antigen delivery systems for vaccine adjuvants and cancer immunotherapy technologies

Cementation of ILW ion exchange resins : Impact of sulfate ions released by radiolysis on hydrated matrix.

International audienceSome of the ion exchange resins used during treatment of spent nuclear fuels are intermediate level radioactive wastes which may be damaged by radiolysis process, releasing sulfate ions directly into the cement-based encapsulating material. This work consists in an experimental study of the resulting sulfate attack on the properties of the hydrated matrix dimensional stability, mineralogy and microstructure of the samples as well as variations in the chemical composition of the curing solution were studied during six months. Three sites of delayed ettringite formation were detected into the cement matrix near the surface exposed to solution, localized in the interfacial transition zone between cement matrix and resins, or progressively replacing the portlandite that initially fulfilled the cracks of anionic resins. During the experiment period, the ettringite precipitation and the expansion detected were moderate, and did not lead to cracking. The material involved was considered as having a good resistance to sulfate attack

La géochimie organique des sédiments marins profonds. Mission orgon 3, 1976 (Mauritanie, Sénégal, Iles du Cap-Vert). Généralités et résultats obtenus à la mer. Organic Geochemistry of Deep Marine Sediments. Orgon 3 Mission, 1976 (Mauritania,Senegal,Cape Verde Islands). General and Results Obtained At Sea

Sept articles distincts traitent, le premier des généralités sur la mission ORLON 3, le second du cadre géologique général, les cinq autres des résultats obtenus à la mer dans les domaines de l'interprétation des profils d'échosondeur, de la descrip-tion des carottes, de l'examen de la matière organique figurée, de l'étude des gaz occlus et enfin de la microbiologie. Les profils d'échosondeur permettent de préciser la topographie des fonds, qui apparaissent comme entaillés de canyons. Ils permettent aussi de déceler les glissements sédimentaires qui apparaissent comme un processus normal de mise en place des sédiments dans la région étudiée. La description immédiate des carottes a permis, en particulier, de mettre en évidence des niveaux turbiditiques à éléments bioclastiques subsistant sous la lysocline, ce qui, entre autres, confirme les considérations précédentes. L'examen de la matière organique figurée fait soupçonner l'importance de l'apport détritique éolien, ce qui est une nouveauté. L'étude des gaz occlus oppose nettement la région Nord (radiale de Nouadhibou), au Sud (région des fleuves côtiers et du canyon de Kayar). Dans cette dernière, les gaz ne contiennent pratiquement que du méthane comme hydrocarbure ; les teneurs sontirrégulièrement réparties et ne montrent aucune corrélation, ni avec la teneur en carbone organique, ni avec la richesse microbienne des niveaux. Au Nord, le méthane est un peu moins prédominant (l'éthane représente quelques centièmes du méthane, les homologues supérieurs sont à l'état de traces). S'il n'y a pas corrélation avec la richesse microbienne, il y en a par contre avec la teneur en carbone organique et les teneurs s'accroîssent régulièrement en profondeur pour atteindre le double des teneurs mesurées au Sud. L'interprétation de ces données n'est pas évidente. La microbiologie a mis en évidence un phénomène déjà entrevu aux précédentes missions ORLON. A la pauvreté générale en bactéries des sédiments étudiés, jointe à la disparition totale de ces bactéries très rapidement dans la profondeur des carottes, se superpose ici, dans des niveaux profonds différents suivant les carottes, une microflore très abondante et active (non sporulée). L'importance géologique de cette découverte ne saurait être sous-estimée. <br> Seven separate articles will be published on the ORLON 3 mission.The first will deal with general aspects, the second with the general geological setting and the other five with the results obtained at sea in the fields of interpreting echosounder profiles, describing tore samples, observing parriculote organic motter, examining entrapped gas and investigating microbiology. Echosounder profiles describe the topography of the sea bed which appears to be slashed by canyons. They also detect sedimentary sliding which appears as a normal process of sediment deposition in the region being investigated. The im.nediate description of core samples in particular revealed turbidite levels with bioclastic elements subsisting under the lysocline, thus confirming the preceding considerations among others. An examination of the figured elements in the organic matter suggests the importance of eolian detrital influx, which is something new. An analysis of the entrappeci gas gives rise ta clearcut opposition between the northern region (radial of Nouadhibou) and the southern region (a region of coastal rivers and the Kayar canyon). In the latter region, the gas contains almost nothing other thon methane as a hydrocarbon. The amounts of methane in the gas are irregularly distributed and show no correlation either with the organic carbon contents or with the microbial richness of the levels. In the north the methane is slightly less predominant (ethane represents a few hundredths of methane, and the upper homo-logous series have merely traces). Although there is no correlation witb the microbial richness, there is nonetheless one with the organic carbon content which increases regularly at depth to attain double the amounts measured in the south. The interpretation of such data is not obvious.Microbiology revealed a phenomenon thot had already been glimpsed during preceding ORLON missions. In addition ta the general bacterial poverty of the sediments analyzed, combined with the total disappearance of such bacteria very quickly as depth increases in the cores, is here superimposed the presence of some discrete levels, at depths depending on the cores, where thrives a very abundant and active (unsporulated) microflora

Kinetics of the Reaction of Methyl Iodide with Hydroxylamine in an Aqueous Solution within the Framework of Nuclear Spent Fuel Reprocessing

International audienc

Incorporation of aluminum into C-S-H structures: From synthesis to nanostructural characterization

International audienceC-A-S-H (C=CaO, A=Al$_2$O$_3$, S=SiO$_2$, H=H 2O in cement nomenclature) phases have been synthesized from CaO, SiO$_2$, and AlNaO$_2$. The initial CaO/SiO$_2$ (C/S$_{initial}$) ratios varied from 0.8 to 1.5 and the initial Al$_2$O$_3$/SiO$_2$ (A/S$_{initial}$) ratio was set to 0.1. Samples were characterized by X-ray diffraction and chemical analyses of their equilibrium solutions. This paper describes experiments using a low-voltage scanning transmission electron microscopy (STEM-in-SEM) imaging system that allows transmission observations in an environmental scanning electron microscope. Observations of the nanostructure were also performed by transmission electron microscopy (TEM). Two types of morphologies were clearly observed: fine fibrillar aggregates and small plates, the latter being particularly sensitive to beam damage. Despite their different appearance, both of these phases were amorphous, and the small plates were richer in aluminum. The fraction of the small plate phase increased with the C/S$_{initial}$ ratio. TEM interpretations showed that C-A-S-H phases were not stable under the electron beam and high-magnification observations could significantly modify their structure. Images and chemical analyses acquired with STEM-in-SEM appeared as valuable sources of information because they offered a large observation field comparable to a transmission electron microscope and better magnification resolution than a classical scanning electron microscope

Relevance of the choice of spark plasma sintering parameters in obtaining a suitable microstructure for iodine-bearing apatite designed for the conditioning of I-129

The high chemical durability of iodine-bearing apatite phases makes them potentially attractive for immobilizing radioactive iodine. Reactive spark plasma sintering provides a dense ceramic as a wasteform. A design-of-experiments (DOE) approach was adopted to identify the main process/material parameters and their first order interactions in order to specify experimental conditions guaranteeing complete reaction, relative density of the wasteform exceeding 92% and the largest possible grain size. For a disposal of the wasteform in a deep geological repository, these characteristics allow minimization of the iodine release by contact with groundwater. It was found that sintering at a temperature of 450 degrees C with an initial specific surface area of 3.3 m(2) g(-1) for the powder reactants is sufficient in itself to achieve the targeted characteristics of the wasteform. However, this relies on a liquid sintering regime the efficiency of which can be limited by the lead iodide initial content in the mix as well as by its particle size. (C) 2014 Elsevier B. V. All rights reserved