Study of structure and orientation of mesentericin Y105, a bacteriocin from Gram-positive Leuconostoc mesenteroides, and its Trp-substituted analogues in phospholipid environments

AbstractMesentericin Y105 (Mes-Y105) is a bacteriocin secreted by Leuconostoc mesenteroides which is particularly active on Listeria. It is constituted by 37 residues and reticulated by one disulfide bridge. It has two W residues, W18 and W37, which can be studied by fluorescence. Two single substituted W/F analogues were synthesized (Mes-Y105/W18 and Mes-Y105/W37) to differentiate the local environment around each W and to study their changes in the presence of lipid vesicles.Fluorescence experiments show that, for the pure Trp-analogues, W18 and W37 are fully exposed to solvent whatever pH and buffer conditions. In the presence of lipid vesicles, both became buried. Lipid affinities were estimated: they are weak for zwitterionic phospholipids but an order of magnitude higher for negatively charged phosphatidylserine (PS) and phosphatidylglycerol (PG) lipids. On negatively charged PG lipids, Mes-Y105 and Mes-Y105/W37 display comparable lipid affinities. A decrease in lipid affinity is observed for Mes-Y105/W18 compared to Mes-Y105, which means that W37 would seem to be required for increased lipid selectivity. In the lipid-bound state W18 is strongly dehydrated, probably embedded into the acyl chains, while W37 stands more at the interface.Mes-Y105 was also studied by polarization modulation infrared reflection absorption spectroscopy (PMIRRAS), alone and in various phospholipid environments, to obtain structural information and to assess lipid perturbations. At nanomolar concentrations close to those required for anti-Listeria activity, Mes-Y105 forms films at the air/water interface and inserts into negatively charged lipid monolayers. In situ infrared data show that Mes-Y105 binding only affects the polar head group vibrations while the lipid order of the acyl chains remains unaffected. The PMIRRAS show that Mes-Y105 folds into an N-terminal antiparallel β-sheet followed by an α-helix, both structures being tilted (40°) compared to the normal at the interface, which is in agreement with the thickness estimated by Brewster angle microscopy (BAM). All these data support the proposal of a new model for Mes-Y105 at the membrane interface

Targeting the dimerization initiation site of HIV-1 RNA with aminoglycosides: from crystal to cell

The kissing-loop complex that initiates dimerization of genomic RNA is crucial for Human Immunodeficiency Virus Type 1 (HIV-1) replication. We showed that owing to its strong similitude with the bacterial ribosomal A site it can be targeted by aminoglycosides. Here, we present its crystal structure in complex with neamine, ribostamycin, neomycin and lividomycin. These structures explain the specificity for 4,5-disubstituted 2-deoxystreptamine (DOS) derivatives and for subtype A and subtype F kissing-loop complexes, and provide a strong basis for rational drug design. As a consequence of the different topologies of the kissing-loop complex and the A site, these aminoglycosides establish more contacts with HIV-1 RNA than with 16S RNA. Together with biochemical experiments, they showed that while rings I, II and III confer binding specificity, rings IV and V are important for affinity. Binding of neomycin, paromomycin and lividomycin strongly stabilized the kissing-loop complex by bridging the two HIV-1 RNA molecules. Furthermore, in situ footprinting showed that the dimerization initiation site (DIS) of HIV-1 genomic RNA could be targeted by these aminoglycosides in infected cells and virions, demonstrating its accessibility

Le risque de feux de brousse sur la Grande Terre de Nouvelle-Calédonie : l’Homme responsable, mais pas coupable

Depuis des années en Nouvelle-Calédonie, les feux anthropiques croissent en nombre, fréquence et étendue, menaçant la conservation des écosystèmes et devenant un danger pour les populations. Les estimations montrent que les feux de forêt et de brousse dévastent en moyenne chaque année de 20 000 à 50 000 ha soit près de 3 % de la superficie totale de l’archipel. Au delà de la perte de biodiversité, il en résulte le cortège des risques d’impacts indirects des incendies : assèchement des cours d’eau en saison sèche, appauvrissement des sols, accélération du processus de désertification, aggravation du ruissellement, augmentation de l’érosion des sols, phénomènes d’hypersédimentation, étouffement des récifs coralliens, etc., autant de maux qui affectent directement les populations locales et leur milieu de vie dont une grande partie se nourrit des produits d’une agriculture vivrière traditionnelle et ou d’une pêche artisanale. Cependant malgré les enjeux liés à la gestion de ce risque majeur, l’une des constatations que nous pouvons faire, au-delà du manque de moyens humains et techniques de lutte, est une connaissance fragmentaire sur la répartition et les causes des incendies en Nouvelle-Calédonie. Cette communication, présentant quelques résultats du programme ANR INC (Incendies et biodiversité des écosystèmes en Nouvelle-Calédonie), aura comme objectifs d’analyser la distribution spatiale de l’occurrence des feux détectés par les satellites MODIS. Ces informations seront croisées au travers d’un SIG à des indicateurs spatialisés de type statuts fonciers (terrains coutumiers/privé) socio-économiques (taux de chômage, niveau scolaire, origine ethnique..) afin d’identifier des facteurs corrélés aux départs d'incendies. Dans un deuxième temps, l’étude de la perception de ce risque chez les populations Kanak nous permettra de mettre en évidence les causes principales des feux de brousse non maîtrisés.In New Caledonia, for many years, anthropogenic fires have been increasing in number, frequency and extent, posing a threat to the conservation of ecosystems and a danger to human populations. Estimates show that forest fires and bushfires devastate an average of 20,000 to 50,000 ha a year, which represents about 3% of the total surface area of the archipelago. Above and beyond biodiversity loss, fires can cause a range of indirect negative impacts (dried-up watercourses in the dry season, soil depletion, accelerated desertification, increased run-off and soil erosion, hypersedimentation phenomena, smothering of coral reefs etc.), which directly affect the environment and local populations, many of whom rely on subsistence farming and/or small-scale fishing. However, despite the challenges associated with managing this major risk, it is clear that, in addition to the shortage of human and technical fire-fighting resources, the knowledge about the distribution and causes of fires in New Caledonia is fragmentary. This paper describes some of the results of the research project (Fires and ecosystem biodiversity in New Caledonia) and aims to analyse the spatial distribution of fires detected by the MODIS satellites. This information will be cross-referenced in a GIS with spatial indicators highlighting both land tenure (customary/private land) and socio-economic status (unemployment rates, educational attainment, ethnicity etc.) in order to identify factors relating to outbreaks of fire. Second, studying the perception of risk among the Kanak populations will allow us to highlight the main causes of uncontrolled bushfires

Expression, purification, crystallization and preliminary X-ray analysis of the cathelicidin motif of the protegrin-3 precursor

International audienc

Aqueduc et structures hydrauliques de la <i>villa</i> de Richeaume I à Puyloubier (Bouches-du-Rhône)

International audienceEine von 1998 bis 2003 an der antiken Fundstelle von Richeaume I (Puyloubier, Dép. Bouches-du-Rhône) durchgeführte Plangrabung führte zur Entdeckung einer ausgedehnten Villenanlage. Sie nimmt eine Fläche von mehr als 5.000 m2 ein und war vom ersten Jahrhundert v. Chr. bis zu Beginn des sechsten Jahrhunderts n. Chr. belegt. Sie war durch eine Wasserleitung versorgt, die die Quellen im Norden des Geländes faβt, und von einer bestimmten Anzahl ländlicher Siedelplätze umgeben, die häufig schon in der jüngeren Eisenzeit bestanden. Die auf 2.000 m2 freigelegten archäologischen Überreste betreffen die Wohnbereiche und die landwirtschaftlichen Bereiche der frühkaiserzeitlichen und spätantiken Villa sowie verschiedene wasserbauliche Vorrichtungen (Zierbecken, Leitungskanäle, Abwasserleitungen, Staumauern, Entwässerungsgräben und Reste der Wasserleitung). Die hier vorgetragenen Überlegungen beziehen sich auf die wasserbaulichen Anlagen, die durch geophysikalische Prospektion und archäologische Grabungen auf dem Osthang des Platzes zwischen 315,94 m und 314,05 m ü. N. N. entdeckt wurden. Von diesen Anlagen (Staumauer, Altarm eines Gewässerlaufs, Abschnitte der Wasserleitung) fallen insbesondere Überreste einer Wasserleitung auf die man nur mit der Wasserversorgung der Wohn- und Stallbereiche der weiter bergauf gelegenen Villa in Verbindung bringen kann. Die beschriebene Vorrichtung, bei der die stark abschüssige Hanglage die Errichtung eines gewaltigen Unterbaus erzwang, dürfte mit der Versorgung eines der benachbarten Gebäude zusammenhängen, dessen genaue Funktion noch zu untersuchen wäre.A research excavation on the Richeaume I site (Puyloubier, Bouches-du-Rhône) took place between 1998 and 2003. This revealed the presence of a substantial villa, covering an area of 5 000 m2 that was occupied from the 1st century BC through to the 4th century AD. An aqueduct, which channelled water from a number of springs to the north of the site, supplied the site. A number of other sites that were initially settled during the late Iron Age surround Richeaume I. The archaeological remains excavated covered an area of 2 000 m2 and revealed elements of the agricultural and domestic areas of the villa, as well as hydrological structures (ornamental pond, water conduits, sewers, dykes, drains and aqueduct remains). This article presents an analysis of the hydrological structures discovered by geophysical survey, which were subsequently excavated, on the western side of the site between 315,94 m and 314,05 m above sea level. Within these structures (dyke, palaeochannel and sections of aqueduct) the most important element is an aqueduct that cannot be directly associated with the supply of water to the residential and agricultural parts of the villa upstream. The presence of this structure, which is characterised by a substantial slope, required the construction of a substantial foundation wall. Therefore, this structure could have been associated with the water supply to one of the adjacent buildings whose characteristics still need to be ascertained.Une fouille archéologique programmée, entreprise de 1998 à 2003 sur le site antique de Richeaume I (Puyloubier, Bouches-du-Rhône), a révélé la présence d'une vaste villa de plus de 5 000 m2 occupée du Ier s. av. J.-C. au début du VIe s. apr. J.-C., alimentée par un aqueduc captant les eaux de source au nord et entourée d'un certain nombre d'établissements ruraux souvent hérités du second âge du Fer. Les vestiges archéologiques mis au jour sur une superficie de 2 000 m2 correspondent aux parties résidentielle et agricole de la villa du Haut-Empire et de l'Antiquité tardive ainsi qu'à divers aménagements hydrauliques : bassins d'agrément, canalisations, égouts, murs de digue, drains et vestiges d'aqueducs. L'étude proposée ici porte sur les structures hydrauliques découvertes par la prospection géophysique et les fouilles archéologiques sur le versant oriental du site entre 315,94 et 314,05 m d'altitude. Parmi ces structures (mur de digue, paléochenal, tronçons d'aqueduc) se distinguent plus particulièrement les vestiges d'un aqueduc qui ne peut être mis en relation avec l'alimentation en eau des parties résidentielle et agricole de la villa situées plus en amont. Cet ouvrage, dont la pente à forte déclivité a nécessité la construction d'une imposante substruction, pourrait être associé à l'alimentation en eau d'un des bâtiments voisins dont la nature reste à définir

Higher Toxicity with 42 Gy in 10 Fractions as a Total Dose for 3D-Conformal Accelerated Partial Breast Irradiation: Results from a Dose Escalation Phase II Trial

Objective: Recent recommendations regarding indications of accelerated partial breast irradiation (APBI) have been put forward for selected breast cancer (BC) patients. However, some treatment planning parameters, such as total dose, are not yet well defined. The Institut Gustave Roussy has initiated a dose escalation trial at the 40 Gy/10 fractions/5 days and at a further step of total dose (TD) of 42 Gy/10 fractions/5 days. Here, we report early results of the latest step compared with the 40 Gy dose level. Methods and materials: From October 2007 to March 2010, a total of 48 pT1N0 BC patients were enrolled within this clinical trial: 17 patients at a TD of 42 Gy/10f/5d and 31 at a TD of 40 Gy/10f/5d. Median follow-up was 19 months (min-max, 12–26). All the patients were treated by APBI using a technique with 2 minitangents and an “enface” electrons delivering 20% of the total dose. Toxicities were systematically assessed at 1; 2; 6 months and then every 6 months. Results: Patients’ recruitment of 42 Gy step was ended owing to persistent grade 3 toxicity 6 months after APBI completion (n = 1). Early toxicities were statistically higher after a total dose of 42 Gy regarding grade ≥2 dry (p = 0.01) and moist (p = 0.05) skin desquamation. Breast pain was also statistically higher in the 42 Gy step compared to 40 Gy step (p = 0.02). Other late toxicities (grade ≥2 fibrosis and telangectasia) were not statistically different between 42 Gy and 40 Gy. Conclusions: Early toxicities were more severe and higher rates of late toxicities were observed after 42 Gy/10 fractions/5 days when compared to 40 Gy/10 fractions/5 days. This data suggest that 40 Gy/10 fractions/5 days could potentially be the maximum tolerance for PBI although longer follow-up is warranted to better assess late toxicities

The EPOC project: Energy Proportional and Opportunistic Computing system

15397International audienceWith the emergence of the Future Internet and the dawning of new IT models such as cloud computing, the usage of data centers (DC), and consequently their power consumption, increase dramatically. Besides the ecological impact, the energy consumption is a predominant criteria for DC providers since it determines the daily cost of their infrastructure. As a consequence, power management becomes one of the main challenges for DC infrastructures and more generally for large-scale distributed systems. In this paper, we present the EPOC project which focuses on optimizing the energy consumption of mono-site DCs connected to the regular electrical grid and to renewable energy sources

Security Architecture for Point-to-Point Splitting Protocols

International audienceThe security of industrial supervisory control and data acquisition systems (SCADA) has become a major concern since the Stuxnet worm in 2010. As these systems are connected to the physical world, this makes them possibly hazardous if a malicious attacker is able to take over their control. SCADA can live up to 40 years, are particularly hard to patch, and quite often have no security feature at all. Thus, rather than securing them, network segregation is often used to prevent attackers from entering the industrial system. In this paper, we propose a generic solution: embed a point-to-point splitting protocol within a physical device, thus able to physically isolate networks, perform deep packet inspection and also provide encryption if necessary. We obtain a kind of next generation firewall, encompassing at least both diode and firewall features, for which conformity to security policies can be ensured. Then we define a set of associated security properties for such devices and the requirements for such a device's security architecture and filtering rules. Finally, we propose a secure hardware implementation

Morning Plasma Melatonin Differences in Autism: Beyond the Impact of Pineal Gland Volume

While low plasma melatonin, a neuro-hormone synthesized in the pineal gland, has been frequently associated with autism, our understanding of the mechanisms behind it have remained unclear. In this exploratory study, we hypothesized that low melatonin levels in ASD could be linked to a decrease of the pineal gland volume (PGV). PGV estimates with magnetic resonance imaging (MRI) with a voxel-based volumetric measurement method and early morning plasma melatonin levels were evaluated for 215 participants, including 78 individuals with ASD, 90 unaffected relatives, and 47 controls. We first found that both early morning melatonin level and PGV were lower in patients compared to controls. We secondly built a linear model and observed that plasma melatonin was correlated to the group of the participant, but also to the PGV. To further understand the relationship between PGV and melatonin, we generated a normative model of the PGV relationship with melatonin level based on control participant data. We found an effect of PGV on normalized melatonin levels in ASD. Melatonin deficit appeared however more related to the group of the subject. Thus, melatonin variations in ASD could be mainly driven by melatonin pathway dysregulation

Immunological and Metabolomic Impacts of Administration of Cry1Ab Protein and MON 810 Maize in Mouse

We have investigated the immunological and metabolomic impacts of Cry1Ab administration to mice, either as a purified protein or as the Cry1Ab-expressing genetically modified (GM) MON810 maize. Humoral and cellular specific immune responses induced in BALB/cJ mice after intra-gastric (i.g.) or intra-peritoneal (i.p.) administration of purified Cry1Ab were analyzed and compared with those induced by proteins of various immunogenic and allergic potencies. Possible unintended effects of the genetic modification on the pattern of expression of maize natural allergens were studied using IgE-immunoblot and sera from maize-allergic patients. Mice were experimentally sensitized (i.g. or i.p. route) with protein extracts from GM or non-GM maize, and then anti-maize proteins and anti-Cry1Ab–induced immune responses were analyzed. In parallel, longitudinal metabolomic studies were performed on the urine of mice treated via the i.g. route. Weak immune responses were observed after i.g. administration of the different proteins. Using the i.p. route, a clear Th2 response was observed with the known allergenic proteins, whereas a mixed Th1/Th2 immune response was observed with immunogenic protein not known to be allergenic and with Cry1Ab. This then reflects protein immunogenicity in the BALB/c Th2-biased mouse strain rather than allergenicity. No difference in natural maize allergen profiles was evidenced between MON810 and its non-GM comparator. Immune responses against maize proteins were quantitatively equivalent in mice treated with MON810 vs the non-GM counterpart and no anti-Cry1Ab–specific immune response was detected in mice that received MON810. Metabolomic studies showed a slight “cultivar” effect, which represented less than 1% of the initial metabolic information. Our results confirm the immunogenicity of purified Cry1Ab without evidence of allergenic potential. Immunological and metabolomic studies revealed slight differences in mouse metabolic profiles after i.g. administration of MON810 vs its non-GM counterpart, but no significant unintended effect of the genetic modification on immune responses was seen