Activités enzymatiques: glycosidases et peptidase chez Leuconostoc oenos au cours de la croissance bactérienne. Influence des macromolécules de levures

Les macromolécules d'origine pariétale (polysaccharides et proteines) libérées après autolyse de Saccharomyces cerevisiae stimulent fortement le développement de L. oenos en milieu synthétique. Ceci se traduit par un raccourcissement de la phase de latence et par une augmentation de la biomasse formée. Différentes activités enzymatiques (α-D et β-D-glucosidases, N-acétyl-β-D-glucosaminidase, peptidase), mesurées sur cellules entières de L. oenos, augmentent significativement dès la phase de latence lorsque les bactéries sont cultivées en présence de ces macromolécules de levures. Les déterminations du pH optimum et de la température optimale des trois osidases, pariétales pour l'α-D-glucosidase et la β-D-glucosidase et endocellulaire ou périplasmique pour la N-acétyl-β-D-glucosaminidase, montrent que L. oenos possède un équipement enzymatique fonctionnel au pH du vin et aux températures de conservation du vin capable d'hydrolyser partiellement les macromolécules de levures, naturellement présentes en fin de fermentation alcoolique dans le milieu.Osidasic and peptidasic activities in Leuconostoc oenos during bacterial growth. Influence of macromolecules of yeastsCell-wall polyosides and proteins liberated by Saccharomyces cerevisiae after autolysis stimulated the growth of Leuconostoc oenos in a synthetic environment by a shortening of the latence period and a marked increase of bacterial biomass. Activities of alpha-D and beta-D-glucosidases, N-acetyl-beta-D-glucosaminidase and peptidase, in whole cells of L. oenos, increased from the latence period on lactic acid bacteria cultivated with these macromolecules. Temperature optima and pH optima of cell-wall bound alpha- and beta-glucosidases and of soluble N-acetyl-beta-glucosaminidase, indicated that L. oenos is able to hydrolise partially the yeast's macromolecules present in the wine at the end of alcoholic fermentation

SOFI: A 3D simulator for the generation of underwater optical images

International audienceWe present an original simulator-called SOFI-for the synthetic generation of underwater optical images. The simulator architecture is flexible and relies on flow diagrams in order to allow the integration of various models for image generation which are based on the underwater optical phenomena. The objective is also to ensure real time or quasi real time performance so it takes advantage of the latest technologies, such as GPGPU, and relies on GPU programming under CUDA. Two kinds of models for image generation are presented and should be integrated in SOFI: (1) the OSOA model based on the radiative transfer theory and (2) global image modeling which describes globally how an image is deteriorated under the effects of sea water

Facile one-spot synthesis of highly branched polycaprolactone

Reported is the first solvent-free (bulk) synthesis of degradable/bioresorbable, highly branched polymers via tin octanoate Sn(Oct2) catalysed controlled ring opening co-polymerisation (ROP) of mono and di-functional lactone monomers that proceed to near quantitative conversion. The successful isolation of solvent soluble, highly branched structures was shown to be dependent on both the concentration of the di-functional monomer and the overall reaction time. Comparison with analogous systems utilising controlled radical polymerisation (CRP) to form the highly/hyper branched polymers suggested significant experimental differences between the two chain growth methods. The maximum proportion of di-functional monomer without gelation ensuing was found to be 0.6 equivalents w.r.t. mono-functional monomer (c.f. 1 with CRP) and the onset of significant levels of branching occurred at approximately 90% conversion (c.f. ~70% with CRP). These differences and significant disparity in reaction times were attributed to (a) the coordination and insertion (C+I) propagation mechanism adopted by the Sn catalyst and (b) the presence of additional trans-esterification reactions at high conversion. Evidence is presented to support the conclusion that there are two mechanisms contributing to the overall branching process in the ROP system at high conversion. First, the C+I mechanism promotes growth of linear polymer until approximately 90% conversion, after which both the C+I and trans-esterification processes contribute to the interchain branching process. The branched nature of the molecular structures was supported by confirmation plots generated from static light scattering. This data demonstrated that the polymers synthesised exhibit varying degrees of branching, consistent with the di-functional monomer (4,4’-bioxepanyl-7,7’-dione - BOD) concentration in the feed. The degree of branching was calculated using 3 different methods and the results were shown to be independent of method. Finally, DSC analysis of the polymers demonstrated correlation between the degree of branching achieved and the observed Tm for the material where increased branching leads to a drop in the recorded Tm

Assembly-dependent translation of subunits 6 (Atp6) and 9 (Atp9) of ATP synthase in yeast mitochondria

The yeast mitochondrial ATP synthase is an assembly of 28 subunits of 17 types of which 3 (subunits 6, 8, and 9) are encoded by mitochondrial genes, while the 14 others have a nuclear genetic origin. Within the membrane domain (FO) of this enzyme, the subunit 6 and a ring of 10 identical subunits 9 transport protons across the mitochondrial inner membrane coupled to ATP synthesis in the extra-membrane structure (F1) of ATP synthase. As a result of their dual genetic origin, the ATP synthase subunits are synthesized in the cytosol and inside the mitochondrion. How they are produced in the proper stoichiometry from two different cellular compartments is still poorly understood. The experiments herein reported show that the rate of translation of the subunits 9 and 6 is enhanced in strains with mutations leading to specific defects in the assembly of these proteins. These translation modifications involve assembly intermediates interacting with subunits 6 and 9 within the final enzyme and cis-regulatory sequences that control gene expression in the organelle. In addition to enabling a balanced output of the ATP synthase subunits, these assembly-dependent feedback loops are presumably important to limit the accumulation of harmful assembly intermediates that have the potential to dissipate the mitochondrial membrane electrical potential and the main source of chemical energy of the cell

Comparaison de diverses chaines de detection en vue d'applications operationnelles

Afin de décider de la présence ou de l'absence d'un signal noyé dans un bruit parasite, de nombreux auteurs ont introduit divers types de chaînes de détection . Cet article essaie, dans la mesure du possible, d'effectuer une synthèse comparée de ces différents travaux. Le problème de l'ingénieur est de savoir , dans une situation donnée (c'est-à-dire pour des caractéristiques statistiques et spectrales particulières du signal et du bruit, et pour un rapport signal sur bruit donné) quel type de récepteur choisir pour atteindre les performances de détection fixées par le cahier des charges. Ce choix est d'autant plus difficile que la diversité des chaînes de traitement conduit à des grandeurs de sortie de nature physique différente . Pour comparer ces diverses chaînes nous utilisons la notion de rapport [S/B]introduite par A.BLANC-LAPIERRE et B.PICINBONO en 1961. Ce critère compare l'augmentation de composante continue apportée (en sortie du détecteur) par l'arrivée du signal à détecter, aux fluctuations crées par le bruit parasite en l'absence (ou en présence ) de ce signal. Ce dernier traduit le comportement d'un détecteur de seuil , placé en sortie des chaînes de réception et dont la fonction est de donner une information binaire sur la présence ou l'absence du signal

Synthese d'ouverture en acoustique sous-marine : Influence de l'effet doppler differentiel

Lors de la formation d'une antenne synthétique en acoustique sous-marine, la variation de vitesse relative sonar-fond entraîne des variations de phase des signaux en sortie de filtrage adapté. On se propose d'évaluer et de comparer la dégradation de la qualité de l'image due à cet effet dans le cas où l'on tient compte de la phase des signaux pour former l'antenne synthétique et celui où l'on ne tient compte que de l'intensité des signaux

Description of archeological corrosion layers thanks to multivariate analysis

International audiencePredict how corrosion evolves for centuries in iron materials is decisive as well in nuclear field in order to evaluate the nuclear waste containers thickness as in cultural heritage for conservation of metal items. Our goal is to describe the Corrosion Product Layers (CPLs) which grew up under natural conditions in order to understand the corrosion mechanisms and the role of the layer in those phenomena. The aim of this study is to correlate both elementary and structural data thanks to chemometrics. The development of a reliable methodology is based on the case of archeological artefacts corroded in atmosphere. CPLs contain goethite, lepidocrocite, akaganeite and ferrihydrite (Fe$_2$O$_3$, nH$_2$O). Ferrihydrite is an electrochemical reactive phase which can see its reactivity decrease by adsorption of chemical species coming from the environment like phosphate and sulfate [1]. Phases and chemical elements are heterogeneously distributed at micrometric scale and these phenomena have to be taken into account to describe the long term corrosion processes in atmosphere. In order to obtain a representative description on large areas, Raman and SEM-EDX hyperspectral images were acquired on the same zones. Hyperspectral images are about several tens of thousands spectra. Raman data have been analyzed by Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). This algorithm allows to detect every crystalline phases in the analyzed zone and to quantify phase proportion [2]. To evaluate the correlations between structural and chemical data, Raman and EDX hyperspectral images (micrometric resolution) have been examined together. A first approach consists in merging Raman and EDX spectra together after several preprocesses. Then a PCA is used on merged spectra. A second approach is based on the use of component images obtained from the analysis of both datasets separately. For Raman spectroscopy, the quantification images of component extracted by MCR-ALS are used. For EDX, intensity signals of each elements are extracted. Multiblock treatments are performed on the images obtained from these data [3, 4] to specify the possible correlation between elementary and structural information in CPLs. First results on merged spectra, thanks to PCA, seems to show a correlation between phosphorus and other minor elements as sulfur with ferrihydrite on one of the principal components

Genesis of the Loma Galena Deposit, Navidad District, Patagonia Argentina

Trabajo presentado en el XV IAGOD Meeting (International Associations Genesis Ore Deposits), celebrado en Salta (Argentina), del 28 al 31 de agosto de 2018Loma Galena (6410.8 t Ag, 997,130 t Pb) is one of the eight deposits of the world class Ag + Pb ± (Cu, Zn) Navidad district (19.670 t Ag and 1.32 Mt Pb) located in the west of the North Patagonian Massif of Argentina. The deposit was formed in an active continental rift basin during the Middle Jurassic, when subaerial volcanic activity was contemporaneous with lacustrine sedimentation. The normal faults that delimited the horsts and grabens in the deposit and the Sauzal fault, a detachment fault, acted as the main conduits for the upflow of hydrothermal fluids (Fig. 1). The deposit has a lithologic control and the the highest metal anomalies are found in highly permeable and reactive autobrecciated mafic volcanoclastic rocks interbedded in the volcano-sedimentary Cañadon-Asfalto Formation (Fig. 1). The volcanic rocks are high-K basaltic andesite to dacite in composition and they have yielded LA-ICPMS U-Pb zircon ages of 173.9 ± 1.9 Ma and 170.8 ± 3.0 Ma. Lava flows surrounded by autobrecciated carapace were dominantly extruded in subaerial conditions whereas hyaloclastite and peperite facies suggest contemporaneous subaqueous volcanism synchronous with sedimentation. Lacustrine sedimentation represented by calcareous mudstone with pisolithic and laminated limestone, sandstone, chert and coal overlies the volcanic rocks. A Sr-rich evaporite layer interbeded in the sedimentary succession indicates intermittent drying out of the lake and hypersaline conditions. The mineralization occurs in veins and hydrothermal breccias that lie on the structural hanging wall and footwall of the main faults, in mineralized autobreccia and chaotic breccia in the contact between volcanic and sedimentary rocks, and disseminated in the organic-rich sedimentary rocks. The earliest infill of veins and breccias consists of calcite I and siderite with crustiform, cockade and platy textures, followed by two main episodes of mineralization. During the first stage precipitated framboidal pyrite and colloform pyrite, marcasite, galena and sphalerite. During the second stage chalcopyrite, bornite and tennantite-tetrahedrite with minor amounts of covellite and digenite replaced the early sulfides. Colloform bands of pyrite and marcasite show the highest Ag contents, although all sulfides and sulfosalts carry Ag. They are rarely observed in situ, on the walls of veins; they are usually found as transported fragments cemented by several pulses of chalcedony with minor barite. NO ENTIENDO, QUIEN? Late infill consists of calcite II, barite II, quartz and strontianite. Hydrothermal breccias present voids with a geopetal infilling with detrital material of sand-silt size and variable composition (chalcedony, quartz, calcite, ankerite, barite, galena, pyrite, marcasite, altered volcanic and sedimentary rock fragments) with parallel lamination. Volcanic rocks next to veins and breccias are altered and replaced by adularia, calcite, celadonite, quartz, and chlorite, sulfides, chalcedony, abundant clay minerals (kaolinite and smectite with minor illite-smectite mixed layers and traces of tosudite), Fe-Mg-Mn carbonates and calcite II; there are relicts of early albite. In the sedimentary rocks, the clasts are partially to completely replace by chalcedony, kaolinite and carbonates. Calcite and chalcedony also fills micro-veinlets. The sulfur isotopic signatures of sulfides hosted in veins and hydrothermal breccias (34S -0.9 to +8.3) are more restricted than the 34S of sulfides hosted in the autobreccia, chaotic breccia and sedimentary rocks (34S -15.4 to +12.9). The sulfur isotopic signature of hydrothermal barite varies between +15.7 and +22.0. The isotopic composition of celestite from the evaporite layer in the sedimentary rocks is 35.3Peer reviewe

Analysis of the underwater image degradation using radiative transfer modeling. Application to submarine image visibility

International audienc

Detection of Echinococcus multilocularis in wild boars in France using PCR techniques against larval form

Recently, new data have been collected on the distribution and ecology of Echinococcus multilocularis in European countries. Different ungulates species such as pig, goat, sheep, cattle and horse are known to host incomplete development of larval E. multilocularis. We report a case of E. multilocularis portage in two wild boars from a high endemic area in France (Department of Jura). Histological examination was performed and the DNA was isolated from hepatic lesions then amplified by using three PCR methods in two distinct institutes. Molecular characterisation of PCR products revealed 99% nucleotide sequence homology with the specific sequence of the U1 sn RNA gene of E. multilocularis, 99 and 99.9% nucleotide sequence homology with the specific sequence of the cytochrome oxydase gene of Echinococcus genus and 99.9% nucleotide sequence homology with a genomic DNA sequence of Echinococcus genus for the first and the second wild boar, respectively. (c) 2004 Elsevier B.V. All rights reserved