Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Despite many studies, our understanding of silica precipitation from natural waters remains limited, in particular for geothermal waters. Here we present a detailed study on the kinetics of silica polymerization as a function of fluid temperature and pH using high-temperature (250-260 °C) seawater-derived geothermal fluids as those discharged from the Bouillante geothermal site.We monitored the on-site decrease in monomeric silica concentration(initial SiO2 concentration of about 600 mg/l)with time using the molybdenum blue spectrophotometric method on samples of separated water collected from the high-pressure separator at 167 °C and cooled to 25, 50, 75, and 90 °C and for pH values ranging from 5 to 8. During all these experiments, only silica polymerization was observed, with the formation of colloidal particles in suspension in the solutions. No scaling of amorphous silica was formed. The collected data were after modeled in order to determine the useful kinetic parameters for predicting and preventing amorphous silica precipitation in the production wells during fluid exploitation in the specific context of Bouillante. Results under the investigated experimental conditions show that the kinetics of silica precipitation is affected more strongly by pH than by temperature change. The reaction in the acidic Bouillante solution begins with a transition period that significantly decreases the kinetics of silica polymerization. Modeling the experimental data indicates that the silica polymerization up to the state of equilibrium is characterized by a 2nd-order kinetic law relative to dissolved silica; this could indicate that the polymerization is controlled mainly by the formation of dimers. However, the first hour of the experiments is better characterized by a 4th-order kinetic law, suggesting more complex polymerization reactions in the initial stage with the formation of nanocolloidal particles containing 3 to 4 monomers. In both cases, the corresponding kinetics rate constant k is linearly dependent on pH for pH between 5 and 7. The activation energy Ea for the overall reaction, calculated using the Arrhenius equation under the considered pH and temperature conditions, ranges between 41±9.8 and 54±9.6 kJ/mol. To complete this work, the colloid particles formed at the end of the kinetics experiments were extracted and analyzed by SEM and TEM microscopy, X-ray Diffraction and the BET method. Results show that the size of the colloids increase and their specific surface decrease with increasing pH and are thus dependent on pH. Globally, our work provides a reliable database for understanding silica polymerization kinetics in natural geothermal brines or geologic waters characterized by a near neutral pH and moderate dissolved silica concentrations.
ISSN: 0009-2541

hal-01403092
https://hal-brgm.archives-ouvertes.fr/hal-01403092
DOI : 10.1016/j.chemgeo.2016.08.031

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
AIMS: Virus detection has often been difficult due to a low concentration in water. In this study, we developed a new procedure based on concentration of virus particles on an innovative support: poly-L-lysine dendrigrafts (DGL), coupled with directed nucleic acid extraction and real-time PCR quantification. METHODS AND RESULTS: This method was evaluated using the bacteriophage MS2 as a model virus. This virus exhibited the size and structural properties of human pathogenic enteric viruses and has often been used to assess new supports of concentration. Moreover, this bacteriophage is also a faecal contamination indicator. In this study, many water filtration conditions were tested (volume of water, concentration, etc.), and more than 80% of bacteriophage were recovered after filtration on polymer, in most conditions. We demonstrated that the method was linear (slope = 0*99 ± 0*04 and Y intercept when x = -0*02 ± 0*28), valid (as manipulators, tested concentrations, volumes of sample and batch of polymer did not have any influence on concentration) and sensitive (allowing to concentrate up to 16,600-fold 1 l of sample and to detect and quantify down to 750 GC l(-1) and 7500 GC l(-1), respectively). CONCLUSIONS: To conclude, this support exhibits high interest to retain viruses and to allow to detect low concentration of virus in water. SIGNIFICANCE AND IMPACT OF THE STUDY: This study gives valuable advance in the methods of concentration and diagnosis of virus in water.
Journal of Applied Microbiology

hal-00828987
https://hal.archives-ouvertes.fr/hal-00828987
DOI : 10.1111/jam.12209
PUBMED : 23551794

Résumé : Le fluide chaud produit par les forages de la centrale géothermique de Bouillante (Guadeloupe) est enrichi en espèces dissoutes telles que la silice qui peuvent précipiter sous forme de dépôts solides lors de son refroidissement et gêner fortement la production électrique. L’un des principaux objectifs de ce travail de thèse a donc été d’améliorer l’état des connaissances sur les conditions physiques, chimiques et cinétiques de la précipitation de la silice amorphe à Bouillante. Après une étude des caractéristiques physico-chimiques des fluides et des dépôts associés au champ de Bouillante, des expériences sur la cinétique de précipitation de la silice, sur site, pour une large gamme de température (25 - 90°C) et de pH (4 - 12) ont été menées et analysées en détail.Pour l’ensemble de ces expériences, seule la polymérisation (réversible) de la silice dissoute, sous forme de suspensions colloïdales très stables en solution, a été observée. La modélisation des données expérimentales de cinétique montre que la vitesse de polymérisation de la silice suit une loi d’ordre 2 vis-à-vis de la silice dissoute jusqu’à l’équilibre en accord avec une dimérisation de la silice. Par contre, durant l’étape initiale de la réaction, une loi d’ordre 4 semble mieux adaptée, suggérant des réactions de polymérisation plus complexes avec formation de tétramères. La température a un effet limité sur la cinétique de polymérisation de la silice comparé à l’effet du pH qui est beaucoup plus important. L’énergie d’activation de la réaction globale est de 41 - 54 kJ pour des pH compris entre 5 et 8.La caractérisation de la silice précipitée a mis en évidence des différences notables entre la structure poreuse de la silice solide prélevée sur les installations de surface et celle de la silice colloïdale obtenue par polymérisation lors des expériences de cinétique, ce qui semble indiquer que des mécanismes différents interviennent dans ces deux contextes de précipitation de la silice dissoute.Le deuxième objectif de cette thèse était d’évaluer la possibilité de valoriser la silice extraite de l’eau géothermale de Bouillante dans un procédé de traitement des eaux naturelles par adsorption. Pour cela, les propriétés d’adsorption de la silice géothermale brute et fonctionnalisée par le poly(ethylèneimine) (ou PEI) ont été étudiées pour deux polluants : un colorant, le bleu de méthylène et un métal lourd, le plomb. Les résultats obtenus montrent que la silice brute possède une grande capacité d’adsorption vis-à-vis du bleu de méthylène. En outre, la fonctionnalisation de la silice par le PEI permet d’améliorer sa capacité d’adsorption vis-à-vis du plomb en solution, en accord avec un modèle cinétique du pseudo-second ordre suggérant une chimisorption. Le modèle d’isotherme de Redlich-Peterson est également en très bon accord avec les données expérimentales.
The hot geothermal fluid produced by the geothermal power plant of Bouillante (Guadeloupe) contains various dissolved components such as silica that can precipitate as solid deposits during their cooling and cause serious problems on the electricity generation. One of the aim of this study is to improve the understanding on the physical, chemical and kinetics conditions of the amorphous silica precipitation in the Bouillante geothermal field. After a study on the physical and chemical characteristics of the Bouillante fluids and deposits which can form during their exploitation, experiments on the kinetics of silica precipitation, on site, under a large range of temperature (25 – 90°C) and pH (4 – 12) have been carried out and analyzed in detail.During on site kinetics experimentations only dissolved silica polymerization (reversible) as colloidal gel, very stable in solution, was observed. Modeling of the experimental data showed that the kinetics polymerization is characterized by a 2-order kinetic law relative to dissolved silica until the equilibrium that is consistent with silica dimerization. On the other side, the initial stage of the reaction is better characterized by a 4-order kinetic law that suggested more complex polymerization reactions with tetramers formation.Temperature has a little effect on the polymerization kinetics compared with the pH which has an effect more important. The activation energy of silica precipitation calculated between 25 and 90°C, is about 41 - 54 kJ for pH ranging to 5 - 8.The characterization of the silica precipitate reveals significant differences in the porous structure of the silica collected on the surface installations and the one obtained from kinetic experiments that suggests different precipitation mechanisms. The second objective of this thesis was to evaluate the possibility to promote geothermal silica for the treatment of natural waters containing contaminants by adsorption. Adsorption properties of the untreated and functionalized by poly(ethylèneimine) (ou PEI) geothermal silica have been investigated for two pollutants: a colorant, the methylene blue and a heavy metal, the lead.Results showed that untreated silica has a great adsorption capacity concerning the methylene blue. Besides, silica functionalization by the PEI allows improving the adsorption capacity for lead in solution. The adsorption kinetics curves followed a pseudo-second order model consistent with a chimisorption. The isotherm model of Redlich-Peterson fitted well the experimental data.

http://www.theses.fr/2014AGUY0698/document

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Virus detection has often been difficult due to a low concentration in water. In this study, we developed a new procedure based on concentration of virus particles on an innovative support: poly-L-lysine dendrigrafts (DGL), coupled with directed nucleic acid extraction and real-time PCR quantification. Methods and Results: This method was evaluated using the bacteriophage MS2 as a model virus. This virus exhibited the size and structural properties of human pathogenic enteric viruses and has often been used to assess new supports of concentration. Moreover, this bacteriophage is also a faecal contamination indicator. In this study, many water filtration conditions were tested (volume of water, concentration, etc.), and more than 80% of bacteriophage were recovered after filtration on polymer, in most conditions. We demonstrated that the method was linear (slope = 0 99 0 04 and Y intercept when x = 0 02 0 28), valid (as manipulators, tested concentrations, volumes of sample and batch of polymer did not have any influence on concentration) and sensitive (allowing to concentrate up to 16 600-fold 1 l of sample and to detect and quantify down to 750 GC l 1 and 7500 GC l 1, respectively). Conclusions: To conclude, this support exhibits high interest to retain viruses and to allow to detect low concentration of virus in water. Significance and Impact of the Study: This study gives valuable advance in the methods of concentration and diagnosis of virus in water.
Journal of Applied Microbiology

hal-00932328
https://hal.archives-ouvertes.fr/hal-00932328
DOI : 10.1111/jam.12209

Éditeur(s) : HAL CCSD
Résumé : EGU2012-6377- Geophysical Research Abstracts vol. 14
The hot geothermal fluid produced by the wells of the Bouillante power station, in Guadeloupe, contains various dissolved species such as silica or some metals (Zn, Pb, etc). During the exploitation, the geothermal fluid is flashing and cooling (from 260 to 160°C for the high-pressure steam-liquid separation and down to 110°C for the low-pressure phase separation of a part of the separated liquid at 160°C). Consequently, the dissolved species can form scale deposits such as amorphous silica or poly-metallic sulphides, according to the exploitation conditions, and cause serious scaling problems on the production and the surface installations. These minerals could also precipitate during the partial underground re-injection of the production fluids which is being set up in the Bouillante power station. In this study, in order to predict and prevent the possible silica precipitation at temperature lower than 160°C, during the partial underground reinjection of the production fluids of Bouillante or their thermal valorization down to 110°C temperatures, we propose to investigate on site the kinetics of silica precipitation as a function of temperature and pH. The experiments presented here were carried out on site on samples of separated waters collected after the steam-water separator at 160°C, containing about 600 ppm of SiO2, at four cooling temperatures: 22, 50, 75 and 90°C, and for pH ranging from 4 to 9. These experiments showed that the silica deposition was always initiated by a polymerization mechanism characterized by an order 2 kinetic law and the formation of a white colloidal gel, which slowed down the silica precipitation under solid form. This latter was observed much later, after the polymerization stage, and only in particular conditions (long time of atmospheric exposure, water stagnation,. . . ). The results also confirmed that the silica precipitation kinetics is strongly dependent on pH. In acidic solution, a transition period is observed before the beginning to the silica polymerization. At neutral-basic pH, there is no transition period and the rate of polymerization is maximal for pH close to 8. The undergoing modeling of these experimental data and specific surface area measurements on the colloidal gel will allow us to determinate the kinetics parameters useful for the prediction and prevention of silica precipitation under the specific exploitation conditions of Bouillante power station. This work is financially supported by ADEME (French Agency for Energy and Environment), BRGM and UAG.
EGU General Assembly 2012
Vienne, Austria

hal-00697627
https://hal-brgm.archives-ouvertes.fr/hal-00697627

Éditeur(s) : HAL CCSD
Résumé : contient des versions PDF d'articles scientifiques (versions éditeur)
Spectrins are actin binding proteins that constitute the main components of membrane skeletons, the protein network located under the plasma membrane. Erythroid or non erythroid (in this case, they are called fodrins), spectrins play an important structural function in the membrane as demonstrated in the red blood cell. Spectrins are composed of two long α and β chains, associated in tetramers (αβ)2, forming the long flexible filaments of the network. Both chains are composed of repeating units which are folded in a triple helical arrangement (A, B and C helices), except for segment α10 which corresponds to a Src Homology 3 domain (SH3). The head-to-head interaction between dimers implies the N-terminal end of α chain and the C-terminal end of β chain. A model was proposed for the tetramerization site of spectrin : the two A and B helices of the last repeat of α chain interact with the C helix of the β chain in order to constitute a triple-helical structure similar to the repeats along the remainder of spectrin molecule. This model was first inferred from the relationship between the severity of the spectrin self-association defect and the location of the underlying mutations found in hereditary elliptocytosis (HE). Using recombinant peptides we defined the region, on both chains, which was sufficient and necessary to generate a fully functional tetramerization site. Producing peptides carrying a βHE mutation, we reproduced the tetramerization defect as observed in red blood cells of patients.
Finally, the presence of an SH3 domain probably gives to spectrins new functions which are different from the stability of the membrane. After contesting the existence of interaction between the fodrin SH3 domain and the α subunit of epithelial sodium channel sensitive to amiloride, we searched for partners of this domain, by screening a rat kidney library with the yeast two-hybrid system. We identified severals proteins implicated in the actin polymerization asoociated with motility or cell differenciation, suggesting that SH3 domain could play a part in this process.
Les spectrines, protéines liant l'actine, sont des constituants majeurs du squelette membranaire, réseau multiprotéique localisé sous la membrane plasmique. Érythroïdes ou non érythroïdes (dans ce cas, on les appelle fodrines), les spectrines ont un rôle structural important dans la membrane comme cela a déjà été démontré, pour la spectrine, dans le globule rouge. Elles sont constituées de deux longues chaînes a et ß associées côte à côte en tétramères (aß)2 qui forment les longs filaments du réseau. Chacune des chaînes est composée par la répétition de segments homologues, 22 pour a et 17 pour ß. Ces segments sont constitués de trois hélices a (hélices A, B et C) repliées sur elles-mêmes. Cette succession de structures trihélicoïdales est parfois interrompue par un domaine particulier comme le domaine SH3 (Src Homology 3) présent au milieu de la chaîne a. Les tétramères (aß)2 de spectrine constituent les filaments du squelette membranaire. L'interaction tête-à-tête de deux dimères aß implique les extrémités NH2 de la chaîne a et COOH de la chaîne ß. D'une part la sévérité du défaut d'auto-association et la localisation des mutations associées à celui-ci et d'autre part, les séquences en acides aminés des extrémités impliquées dans le site d'auto-association ont permis de proposer un modèle : la première hélice C isolée de la chaîne a pourrait s'associer aux deux dernières hélices A et B de la chaîne ß pour reconstituer une unité conformationnelle trihélicoïdale semblable à celles observées le long de la molécule. Un défaut dans la formation du tétramère est le support moléculaire le plus fréquemment observé dans les elliptocytoses héréditaires (HE). À l'aide de peptides recombinants, nous avons défini, sur les deux chaînes, les régions nécessaires et suffisantes possédant les caractéristiques pleinement fonctionnelles du site de tétramérisation. Nous avons ensuite, par mutagenèse dirigée, reproduit le lien entre la présence de mutations HE localisées dans les hélices A ou B et le défaut d'auto-association observé dans les globules rouges de patients HE. La présence d'un domaine SH3 localisé au milieu de la chaîne a confère probablement aux spectrine des fonctions autres que le maintien et la stabilité de la membrane. Les SH3, petits domaines protéiques, participent aux interactions protéine/protéine. Le seul partenaire connu du domaine SH3 de la fodrine était la sous-unité a du canal sodium sensible à l'amiloride (ENaC) mais la fonction de ce complexe n'était pas encore caractérisée. À l'aide de différentes méthodes, nous avons remis en cause l'interaction directe entre ENaC et le SH3 de la fodrine. La fonction de ce domaine SH3 étant liée à la nature de son ligand, nous avons donc recherché les partenaires putatifs du domaine SH3 de la fodrine par la technique du double-hybride. 29 partenaires ont été identifiés, regroupés en 19 familles et 10 clones isolés. La spécificité des interactions a été étudiée à la fois par double-hybride, à l'aide de mutants du domaine SH3 de la fodrine produits par mutagenèse dirigée. Les interactions vis-à-vis d'autres domaines SH3 (spectrine ou une protéine de levure non relatée Scd2) ont été également analysées. Enfin, la spécificité de certains partenaires a été confirmée par des études d'interactions in vitro. Deux des protéines les plus spécifiques du domaine SH3 de la fodrine sont des protéines tyrosine-phosphatase PTP. La première est l'isoforme A de PTP de faible poids moléculaire (LMPTPA) mais l'interaction n'a pas été confirmée in vitro. La deuxième, TD14, est une nouvelle PTP dont la seule fonction connue est d'inhiber la formation des foyers tumoraux des cellules surexprimant l'oncogène Ha-ras. Ces PTP pourraient soit déphosphoryler la fodrine, soit être recrutées sous la membrane pour déphosphoryler une autre cible. Nous avons également identifié trois partenaires (N-WASP, Evl et une protéine de la famille des formines) suggérant que les domaines SH3 des spectrines pourraient être impliqués dans les processus de polymérisation de l'actine liés à la mobilité ou la différenciation cellulaire. Mot clés : spectrine, fodrine, tétramérisation, SH3, double-hybride, polymérisation de l'actine
https://tel.archives-ouvertes.fr/tel-00284819

Droits : info:eu-repo/semantics/OpenAccess
tel-00284819
https://tel.archives-ouvertes.fr/tel-00284819
https://tel.archives-ouvertes.fr/tel-00284819/document
https://tel.archives-ouvertes.fr/tel-00284819/file/Nicolas_1999_-_These.pdf

Éditeur(s) : HAL CCSD De Gruyter
Résumé : International audience
This study aims at better understanding the respective influences of specific gravity (γ), microfibril angle (MFA), and cell-wall matrix polymers on viscoelastic vibrational properties of wood in axial direction. The wide variations of properties between normal wood (NW) and compression wood (CW) are in focus. Three young bent trees (Picea abies, Pinus sylvestris and Pinus pinaster) that recovered verticality were sampled. Several observed differences between NW and CW were highly significant in terms of anatomical, physical (γ, shrinkage, CIELab colorimetry), mechanical (compressive strength), and vibrational properties. Specific dynamic modulus of elasticity (E'/γ) decreases with increasing MFA, and Young's modulus (E') can be satisfactorily explained by γ and MFA. Apparently, the type of the cell wall polymer matrix is not influential in this regard. The damping coefficient (tanδ) does not depend solely on MFA of NW and CW. The tanδ - E'/γ relationship evidences that, at equivalent E'/γ, the tanδ of CW is approx. 34% lower than that of NW. This observation is ascribed to the more condensed nature of CW lignins, and this is discussed in the context of previous findings in other hygrothermal and time/frequency domains. It is proposed that the lignin structure and the amount and type of extractives, which are both different in various species, are partly responsible for taxonomy-related damping characteristics.
ISSN: 0018-3830

hal-00808062
https://hal.archives-ouvertes.fr/hal-00808062
https://hal.archives-ouvertes.fr/hal-00808062/document
https://hal.archives-ouvertes.fr/hal-00808062/file/Changes_viscoelastic_vibrational_Bremaud_al.pdf
DOI : 10.1515/hf-2011-0186

Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
A full equilibrium treatment of molecular aggregation is presented for prototypes of 1D and 3D aggregates, with and without nucleation. By skipping complex kinetic parameters like aggregate size-dependent diffusion, the equilibrium treatment allows to predict directly time-independent quantities such as critical concentrations. The relationships between the macroscopic equilibrium constants for the different paths are first established by statistical corrections and so as to comply with the detailed balance constraints imposed by nucleation, and the composition of the mixture resulting from homogeneous aggregation is then analyzed using the polylogarithm function. Several critical concentrations are distinguished: the residual monomer concentation in equilibrium (RMC) and the critical nucleation concentration (CNC), that is the threshold concentration of total subunits necessary for initiating aggregation. When increasing the concentration of total subunits, the RMC converges more strongly to its asymptotic value, the equilibrium constant of depolymerization, for 3D aggregates and in case of nucleation. The CNC moderately depends on the number of subunits in the nucleus, but sharply increases with the difference between the equilibrium constants of polymerization and nucleation. As the RMC and CNC can be numerically but not analytically determined, ansatz equations connecting them to thermodynamic parameters are proposed
PCCP : Physical chemistry chemical physics

Droits : info:eu-repo/semantics/OpenAccess
hal-01565995
https://hal.archives-ouvertes.fr/hal-01565995
https://hal.archives-ouvertes.fr/hal-01565995/document
https://hal.archives-ouvertes.fr/hal-01565995/file/Aggregates_in_equilibrium.pdf
DOI : 10.1039/c6cp08369b

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Binding of ligand FasL to its receptor Fas triggers apoptosis via the caspase cascade. FasL itself is homotrimeric, and a productive apoptotic signal requires that FasL be oligomerized beyond the homotrimeric state. We generated a series of FasL chimeras by fusing FasL to domains of the Leukemia Inhibitory Factor receptor gp190 which confer homotypic oligomerization, and analyzed the capacity of these soluble chimeras to trigger cell death. We observed that the most efficient FasL chimera, called pFasL, was also the most polymeric, as it reached the size of a dodecamer. Using a cellular model, we investigated the structure-function relationships of the FasL/Fas interactions for our chimeras, and we demonstrated that the Fas-mediated apoptotic signal did not solely rely on ligand-mediated receptor aggregation, but also required a conformational adaptation of the Fas receptor. When injected into mice, pFasL did not trigger liver injury at a dose which displayed anti-tumor activity in a model of human tumor transplanted to immunodeficient animals, suggesting a potential therapeutic use. Therefore, the optimization of the FasL conformation has to be considered for the development of efficient FasL-derived anti-cancer drugs targeting Fas.
ISSN: 1932-6203

hal-00873684
https://hal.archives-ouvertes.fr/hal-00873684
https://hal.archives-ouvertes.fr/hal-00873684/document
https://hal.archives-ouvertes.fr/hal-00873684/file/Functional_Characterization-accepted.pdf
DOI : 10.1371/journal.pone.0054000

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Low Density Polyethylene (LDPE) films were treated by direct fluorination at different conditions, i.e. static and dynamic ones. Modification of the treated films chemical composition was studied by spectroscopic methods (solid state NMR, XPS and infrared spectroscopy). Surface morphology was investigated by SEM and AFM. Also surface energy measurements and electron paramagnetic resonance (EPR) were carried out. Direct fluorination resulted in printability, barrier properties towards O2 and tribological properties enhancement. On the contrary, the barrier properties towards water, initially good, were not improved but maintained.
ISSN: 0257-8972

hal-01324133
https://hal.archives-ouvertes.fr/hal-01324133
DOI : 10.1016/j.surfcoat.2016.03.021

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Vertebrate genomes contain around 20,000 protein-encoding genes, of which a large fraction is still not associated with specific functions. A major task in future genomics will thus be to assign physiological roles to all open reading frames revealed by genome sequencing. Here we show that C2orf62, a highly conserved protein with little homology to characterized proteins, is strongly expressed in testis in zebrafish and mammals, and in various types of ciliated cells during zebrafish development. By yeast two hybrid and GST pull-down, C2orf62 was shown to interact with TTC17, another uncharacterized protein. Depletion of either C2orf62 or TTC17 in human ciliated cells interferes with actin polymerization and reduces the number of primary cilia without changing their length. Zebrafish embryos injected with morpholinos against C2orf62 or TTC17, or with mRNA coding for the C2orf62 C-terminal part containing a RII dimerization/docking (R2D2) - like domain show morphological defects consistent with imperfect ciliogenesis. We provide here the first evidence for a C2orf62-TTC17 axis that would regulate actin polymerization and ciliogenesis.
ISSN: 1932-6203

hal-00955242
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00955242
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00955242/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00955242/file/C2orf62_and_TTC17-accepted.pdf
DOI : 10.1371/journal.pone.0086476

Éditeur(s) : Elsevier Sci Ltd
Résumé : We have studied the exopolysaccharide produced by Cobetia marina DSMZ 4741, a marine bacterium isolated from coastal seawater. This strain is able to produce a polysaccharide in presence of carbon sources as glucose, mannitol and alginate. The maximum production occurs in aerobic condition, during the end of the exponential phase. The polymer is a non-viscous, acidic heteropolysaccharide of 270 kDa constituted of a repeating unit of: →2)-β-D-Ribf-(1→4)-[7,8-O-(Pyr)]-α-D-KDOp-(2→ This kind of chemical structure is generally related to K-antigen polysaccharide of pathogenic Escherichia coli strains. This is the first time this type of EPS is described from a marine bacterium. Moreover the polysaccharide exhibits a pyruvate substitution on its 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) residue never encountered before. The discovery of such an unexpected EPS with high biotechnological potential is a new incentive for a better exploration of bioactive marine resources.
Carbohydrate Polymers (0144-8617) (Elsevier Sci Ltd), 2015-06 , Vol. 124 , P. 347-356

Droits : 2015 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00254/36494/35038.pdf
DOI:10.1016/j.carbpol.2015.02.038
http://archimer.ifremer.fr/doc/00254/36494/

Éditeur(s) : Wiley-blackwell
Résumé : Aims Exopolysaccharides (EPS) are industrially valuable molecules with numerous useful properties. This study describes the techniques used for the identification of a novel Vibrio bacterium and preliminary characterization of its EPS. Methods and Results Bioprospection in marine intertidal areas of New Caledonia followed by screening for EPS producing brought to selection of the isolate NC470. Phylogenetic analysis (biochemical tests, gene sequencing and DNADNA relatedness) permitted to identify NC470 as a new member of the Vibrio genus. The EPS was produced in batch fermentation, purified using the ultrafiltration process and analysed by colorimetry, Fourier Transform Infrared spectroscopy, gas chromatography, Nuclear Magnetic Resonance and HPLC-size exclusion chromatography. This EPS exhibits a high N-acetyl-hexosamines and uronic acid content with a low amount of neutral sugar. The molecular mass was 672x103Da. These data are relevant for possible technological exploitation. Conclusions We propose the name Vibrio neocaledonicus sp. nov for this isolate NC470, producing an EPS with an unusual sugar composition. Comparison with other known polymers permitted to select applications for this polymer. Significance and Impact of the Study This study contributes to evaluate the marine biodiversity of New Caledonia. It also highlights the biotechnological potential of New Caledonia marine bacteria.
Journal Of Applied Microbiology (1364-5072) (Wiley-blackwell), 2013-06 , Vol. 114 , N. 6 , P. 1702-1712

Droits : 2013 The Society for Applied Microbiology
http://archimer.ifremer.fr/doc/00144/25501/24036.pdf
DOI:10.1111/jam.12184
http://archimer.ifremer.fr/doc/00144/25501/

Résumé : La drépanocytose est une hémoglobinopathie aux formes et aux sévérités cliniques très hétérogènes qui affectent de nombreux organes chez les patients touchés. Pour cette raison le terme de syndrome drépanocytaire majeur est généralement employé. Tous les syndromes drépanocytaires majeurs ont en commun une mutation ponctuelle du gène β-globine appelée mutation βs . Cette mutation βs conduit à la synthèse de la protéine d'hémoglobine S (HbS) caractérisée par sa capacité à polymériser dans sa forme désoxygénée. La polymérisation de l'HbS est l'élément déclencheur de la falciformation du globule rouge et conduit à de nombreuses altérations hématologiques et hémorhéologiques. Ces dernières sont à l'origine de troubles de l'hémodynamique, de l'oxygénation sanguine et de la perfusion tissulaire en oxygène. Il en résulte de nombreuses complications aigues (crise vaso-occlusive, accident vasculaire cérébral, syndrome thoracique aigu etc.) et/ou chroniques (glomérulopathie, ostéonécrose de la tête fémorale etc.) causés par un défaut d'oxygénation des tissus.
Sickle cell anemia is a hemoglobinopathy forms and severities very heterogeneous clinical affecting many organs in affected patients. For this reason the term major sickle cell syndrome is generally used. All major sickle cell syndromes have a common point mutation in the gene called β-globin mutation βs. This βs mutation leads to the synthesis of the protein hemoglobin S (HbS) is characterized by its ability to polymerize in its deoxygenated form. The polymerization of HbS is the trigger for the sickling of red blood cells and leads to many Hematological and hemorheological. These are at the origin of disorders hemodynamics, blood oxygenation and tissue perfusion with oxygen. This results in many acute complications (vaso-occlusive crisis, stroke, acute chest syndrome, etc..) And / or chronic (glomerulopathy, osteonecrosis of the femoral head etc.). Caused by a defect of tissue oxygenation.

http://www.theses.fr/2012AGUY0563/document

Éditeur(s) : HAL CCSD
Résumé :  
The main aspects of wood mechanics are approached through the role played by wood as the building material of the tree. The main concepts used by nature: progressive setting up of tree weight and architecture, multifunctional role of wood and adaptability to hazard and long-term evolution, are clarified together with their consequence on the multilayered, anisotropic nature of wood. The technological choices of the plant world as the cellular structure, the use of composite with oriented fibres and hydro-carbonated polymers, as well as the systematic prestressing of every new layer, bear obvious consequences on the type of mechanical behaviour of wood. The local control of the level of prestressing through minor modifications of the cell-wall biosynthesis allows the tree to adapt to conditions of light exploration that will evolve according to time and risk occurrence. This analysis of wood genesis process permits in return to improve our understanding of the mechanical behaviour of the material in relation with the parameters of the microstructure.
Comptes Rendus de l'Académie des Sciences Série 2

hal-01032151
https://hal.archives-ouvertes.fr/hal-01032151
DOI : 10.1016/S1620-7742(01)01380-0

Éditeur(s) : HAL CCSD De Gruyter
Résumé : International audience
Wallaba (Eperua falcata) is a tropical wood which is known to have naturally low swelling characteristics. Samples of wallaba heartwood were subjected to differential solvent extraction. Wood pieces that were extracted with methanol experienced significantly higher swelling after rehydration from oven dry to 96% relative humidity in comparison to non-extracted samples and samples extracted with other solvents. Methanol soluble wallaba heartwood extract was purified by high pressure liquid chromatography and the compounds present were characterised by nuclear magnetic resonance spectroscopy. Methanol extract was found to contain a very high relative proportion of polar compounds which are proposed to bind to the polymeric cell wall by multiple hydrogen bonds restricting the association of water and therefore acting as natural anti-swelling agents.
ISSN: 0018-3830

hal-00856942
https://hal.archives-ouvertes.fr/hal-00856942
https://hal.archives-ouvertes.fr/hal-00856942/document
https://hal.archives-ouvertes.fr/hal-00856942/file/Chemical_extractives_tropical_wood_Royer_al.pdf

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Sickle cell anemia (SCA or SS homozygous sickle cell disease) is an inherited blood disorder caused by single 12 nucleotide substitution in the ␤-globin gene that renders their hemoglobin (HbS) much less soluble than normal hemoglobin 13 (HbA) when deoxygenated. The polymerization of HbS upon deoxygenation is the basic pathophysiologic event leading to 14 RBC sickling, hemolysis, vasoocclusion and ultimately to chronic organ damage. The metabolic changes imposed by exercise 15 may initiate sickling and vaso-occlusive episodes. Further, in patients with SCA, exercise limitation may be related to anemia 16 or chronic complications such as pulmonary vascular disease, congestive heart failure and chronic parenchymal lung disease. 17 Few studies have investigated the cardiorespiratory responses of patients with SCA during either symptom-limited maximal 18 exercise test on cyclo-ergometer or during a six minute walk test. Therefore, patients are advised to start exercise slowly and 19 progressively, to maintain adequate hydration during and after exercise, to avoid cold exposure or sudden change in temperature, 20 and to avoid sports associated with mechanical trauma. There are, however, lack of evidence to allow practitioners to prescribe 21 an exercise program for patients with SCA, and individuals are usually encouraged to exercise on a symptom-limited basis. 22 Finally, this review will also highlight the basic principles that are often used for exercise practice and could be used for exercise 23 prescription and rehabilitation in patients with sickle cell anemia.
ISSN: 1386-0291

hal-01163966
https://hal.univ-antilles.fr/hal-01163966
DOI : 10.3233/CH-2011-1465

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : 51 pages; 15figures; 3 tables, accepted for publication in PloS ONE
International audience
We present a study about AFM imaging of living, moving or self-immobilized, bacteria in their genuine physiological liquid medium. No external immobilization protocol, neither chemical nor mechanical, was needed. For the first time, the native gliding movements of Gram-negative Nostoc cyanobacteria upon the surface, at speeds up to 900microns/h, were studied by AFM. This was possible thanks to an improved combination of a gentle sample preparation process and an AFM procedure based on fast and complete force-distance curves made at every pixel, drastically reducing lateral forces. No limitation in spatial resolution or imaging rate was detected. Gram-positive and non-motile R. wratislaviensis bacteria were studied as well. From the approach curves, Young modulus and turgor pressure were measured for both strains at different gliding speeds and are ranging from 20±3 to 105±5MPa and 40±5 to 310±30kPa depending on the bacterium and the gliding speed. For Nostoc, spatially limited zones with higher values of stiffness were observed. The related spatial period is much higher than the mean length of Nostoc nodules. This was explained by an inhomogeneous mechanical activation of nodules in the Nostoc. We also observed the presence of a soft extra cellular matrix (ECM) around the Nostoc. Both strains left a track of polymeric slime with variable thicknesses. For R. wratislaviensis, it is equal to few hundreds of nanometers, likely to promote its adhesion to the sample. While gliding, the Nostoc secretes a slime layer the thickness of which is in the nanometer range and increases with the gliding speed.
ISSN: 1932-6203

hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765v3/document
https://hal.archives-ouvertes.fr/hal-00769765/file/REsubmission_In-situ_determination_Dhahri_Plos_One_R2_Hal.pdf

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Polarization dependence second harmonic generation (P-SHG) microscopy is gaining increase popularity for in situ quantification of fibrillar protein architectures. In this report, we combine P-SHG microscopy, new linear least square (LLS) fitting and modeling to determine and convert the complex second-order non-linear optical anisotropy parameter ρ of several collagen rich tissues into a simple geometric organization of collagen fibrils. Modeling integrates a priori knowledge of polyhelical organization of collagen molecule polymers forming fibrils and bundles of fibrils as well as Poisson photonic shot noise of the detection system. The results, which accurately predict the known sub-microscopic hierarchical organization of collagen fibrils in several tissues, suggest that they can be subdivided into three classes according to their microscopic and macroscopic hierarchical organization of collagen fibrils. They also show, for the first time to our knowledge, intrahepatic spatial discrimination between genuine fibrotic and non-fibrotic vessels. CCl 4-treated livers are characterized by an increase in the percentage of fibrotic vessels and their remodeling involves peri-portal compaction and alignment of collagen fibrils that should contribute to portal hypertension. This integrated P-SHG image analysis method is a powerful tool that should open new avenue for the determination of pathophysiological and chemo-mechanical cues impacting collagen fibrils organization.
ISSN: 2045-2322

hal-01592192
https://hal.archives-ouvertes.fr/hal-01592192
https://hal.archives-ouvertes.fr/hal-01592192/document
https://hal.archives-ouvertes.fr/hal-01592192/file/s41598-017-12398-0.pdf
DOI : 10.1038/s41598-017-12398-0

Éditeur(s) : HAL CCSD Springer-Verlag Berlin Heidelberg
Résumé : International audience
The main biological function of reaction wood is to act as " muscle " for trees, enabling them to control their posture. The key property to achieve this function is the development of high mechanical stress during the formation of reaction wood cells, called " maturation strains ". Actually, reaction wood formation is basically the asymmetric formation of wood around the tree circumference, with higher maturation strains on the side where reaction wood is formed than on the opposite side. This asymmetry enables stems to bend upward or to compensate for the downward bending induced by gravity. At the cross section level, the performance in this biological function is linked not only to the magnitude of this asymmetry but also to an effect of the cross-sectional size (diameter) of the stem. Eccentric growth and variations in wood mechanical stiffness are second order effects that can modify this performance. Differences in maturation strains between reaction and non-reaction woods are related to their specific cell wall structure and composition. The swelling of the cell wall matrix during maturation and the effect of microfibril angle explain the differences in maturation strains between normal and compression wood. However, this mechanism fails in explaining the high maturation shrinkage of tension wood, and several hypotheses at the molecular levels are still under debate. How trees perceive their gravitational disequilibrium is also an open question for physiologists. Integrative biomechanical modelling (from the polymer level to the cell wall, cross section and whole tree levels) enables defining key variables that explain the performance of reaction wood as a system that insures the stem motricity. Maturation strains can be precisely measured only in recently formed wood at the tree surface, but their changes during the whole tree life can also be estimated by retrospective dendrochronological analysis through structural markers of reaction wood. Lastly, wood in living trees ensures general storage, defence, vascular and skeletal functions, that ask general questions about synergies and trade-offs as the structural characteristics of reaction wood can affect all these functions.
The Biology of Reaction Wood

ISBN : 978-3-642-10813-6
hal-01452085
https://hal.archives-ouvertes.fr/hal-01452085
https://hal.archives-ouvertes.fr/hal-01452085/document
https://hal.archives-ouvertes.fr/hal-01452085/file/Chap_Gril_al_Biomechanical_action_biological_functions_2014.pdf