http://hdl.handle.net/2268/134 Chercher dans ce canal chercher http://orbi.ulg.ac.be/simple-search http://hdl.handle.net/2268/149136 Titre: Structural Determinants of Specificity and Catalytic Mechanism in mammalian 25-kDa Thiamine Triphosphatase <br/> <br/>Auteur, co-auteur: Delvaux, David; Kerff, Frédéric; Murty, Mamidanna R.V.S.; Lakaye, Bernard; Czerniecki, Jan; Kohn, Grégory; Wins, Pierre; Herman, Raphaël; Gabelica, Valérie; Heuze, Fabien; Tordoir, Xavier; Marée, Raphaël; Matagne, André; Charlier, Paulette; De Pauw, Edwin; Bettendorff, Lucien <br/> <br/>Résumé: Background: Thiamine triphosphate (ThTP) is present in most organisms and might be involved in intracellular signaling. In mammalian cells, the cytosolic ThTP level is controlled by a specific thiamine triphosphatase (ThTPase), belonging to the CYTH superfamily of proteins. CYTH proteins are present in all superkingdoms of life and act on various triphosphorylated substrates. Methods: Using crystallography, mass spectrometry and mutational analysis, we identified the key structural determinants of the high specificity and catalytic efficiency of mammalian ThTPase. Results: Triphosphate binding requires three conserved arginines while the catalytic mechanism relies on an unusual lysine-tyrosine dyad. By docking of the ThTP molecule in the active site, we found that Trp-53 should interact with the thiazole part of the substrate molecule, thus playing a key role in substrate recognition and specificity. Sea anemone and zebrafish CYTH proteins, which retain the corresponding Trp residue, are also specific ThTPases. Surprisingly, the whole chromosome region containing the ThTPase gene is lost in birds. Conclusion: The specificity for ThTP is linked to a stacking interaction between the thiazole heterocycle of thiamine and a tryptophan residue. The latter likely plays a key role in the secondary acquisition of ThTPase activity in early metazoan CYTH enzymes, in the lineage leading from cnidarians to mammals. General significance: We show that ThTPase activity is not restricted to mammals as previously thought but is an acquisition of early metazoans. This, and the identification of critically important residues, allows us to draw an evolutionary perspective of the CYTH family of proteins. http://hdl.handle.net/2268/149117 Titre: Characterization of new bacterial glycoside hydrolases isolated from agricultural soils using a functional metagenomic approach <br/> <br/>Auteur, co-auteur: Biver, Sophie; Dubois, Benjamin; Stroobants, Aurore; Portetelle, Daniel; Vandenbol, Micheline <br/> <br/>Résumé: Microorganisms play key roles in soil ecosystem functioning, notably through their ability to degrade plant cell wall polymers. For this, bacteria and fungi produce various enzymes such as cellulases, xylanases, glucosidases, esterases or laccases. Finding new enzymes hydrolyzing cellulose, hemicellulose or lignin is not only interesting for a better understanding of the roles of the soil microflora still largely unknown but these enzymes are also useful for various biotechnological applications such as the production of renewable energy from lignocellulosic material. So here, we used a functional metagenomic approach to isolate new bacterial β-glucosidases, which were then biochemically characterized. The new enzymes were identified by functional analysis of agricultural-soil metagenomic libraries hosted in Escherichia coli and screened on medium containing esculin. After sequence analysis and preliminary estimation of the activity of the new β-glucosidases using p-nitrophenol derivatives on intact bacterial cells, the coding sequences of three of them were cloned into a bacterial expression vector so as to overproduce and purify them by affinity chromatography. The chosen enzymes show only 52-64% sequence identity to known family 3 (GH3) or 1 (GH1) glycoside hydrolases of different phyla (Actinobacteria, Acidobacteria and Proteobacteria). Analysis of the E. coli cells expressing each of them revealed that both GH1 proteins (ASEsc9 and ASEsc10) are thermophilic enzymes more active at mildly acidic to neutral pH while the GH3 enzyme (ASEsc6) is an alkaline, mesophilic, β-glucosidase also displaying xylosidase activity. Their coding sequences have been cloned in fusion with a carboxy-terminal His-tag and placed under the control of the IPTG-inducible promoter of the pET-30b vector. The proteins will be overproduced and purified for further characterization. http://hdl.handle.net/2268/149112 Titre: Identification of lectins as virus competitors in aphid vectors : from fundamental to applied approaches <br/> <br/>Auteur, co-auteur: Bosquée, Emilie; Vandermoten, Sophie; Yu, Wen-Juan; Ronling, Yin; Liu, Yong; Ju-Lian, Chen; Francis, Frédéric http://hdl.handle.net/2268/149109 Titre: Appropriation progressive de l'arganeraie: exploration de l'histoire depuis la genèse des droits jusqu'à leur refonte <br/> <br/>Auteur, co-auteur: Bejbouji, Jihane; Mougenot, Catherine; Mormont, Marc; Qarro, Mohamed; Aziz, Larbi <br/> <br/>Résumé: L’arganeraie, spécificité du Sud-Ouest marocain, est l’ensemble des écosystèmes dont l’espèce caractéristique est l’arganier ou Argania spinosa. Outre leurs multiples fonctions écologiques, ces écosystèmes procurent de nombreux biens pour une population pauvre vivant dans des conditions précaires. Toutefois, cet espace intrigue. En effet, à la différence des autres forêts marocaines dont les riverains ne disposent que de deux droits (la récolte de bois mort gisant et le parcours), la population de l’arganeraie a bénéficié d’une législation spéciale depuis 1925, jouissant ainsi d’une large gamme d’utilisation et d’exploitation des ressources forestières. L’image classique véhiculée de cet espace est celle d’une population autochtone, connue pour son élevage caprin, poursuivant des pratiques ancestrales, notamment l’agdal, et gérant des terrains d’arganiers dont elle tire depuis toujours une huile, aujourd’hui très prisée à l’échelle internationale, et devenue emblématique du Maroc. Les historiens nous livrent pourtant une image contrastée entre recherche de la sécurité et de terrains fertiles et fuite de l’insécurité. Parmi les différentes étapes qui ont jalonné son histoire, nous distinguons pour notre propos deux étapes principales : une première période se situe avant la délimitation des forêts et est marquée par des vagues d’immigration successives venant du sud ; la seconde, à la suite de la colonisation, a remodelé et déstabilisé la situation foncière traditionnelle dans la zone en délimitant un espace domanial. Dans cet article, nous dressons le portrait actuel de l’espace et l’ensemble des droits qui le régissent. Cette construction sociale résulte d’une histoire riche et tourmentée, ayant affecté les modes de gestion des territoires. Pour ce faire, nous avons mobilisé des données d’historiens et d’enquêtes qualitatives et quantitatives réalisées dans le cadre de ce travail ; ces dernières se sont déroulées auprès de 100 ménages, principalement au niveau de trois communes rurales autour du massif du Jbel Amsitten. Il constitue l’une des dix-huit zones centrales de la Réserve de Biosphère de l’arganier, dans le Sud-Ouest marocain. Etant donné que les enquêtes s’intéressent aux usages et pratiques des ménages enquêtés, mais aussi de leurs aïeuls et ascendants, ce travail de recherche pourrait contribuer à reconstruire l’histoire de la zone à partir de celle des personnes interviewées via la compréhension de leur implantation spatiale ou temporelle. Nos enquêtes nous montrent que la population est issue d’un brassage récent d’émigrants du sud. Il s’en suit une trame de droits récemment forgée ; le domanial étant bien distinct du privé avec un rétrécissement des droits concédés par les Français. Renouer avec le corpus de règles qu’entretenait la population avec cet espace-ressources, pourrait être à notre avis, une des principales portes d’entrées à leur conservation. http://hdl.handle.net/2268/149103 Titre: Alternative methods for virus control: the role of symbionts and lectins in viral transmission <br/> <br/>Auteur, co-auteur: Bosquée, Emilie; Chen, Ju Lian; Yong, Lui; Francis, Frédéric http://hdl.handle.net/2268/149073 Titre: Study of bacterial diversity in the topsoil and below the hardpan in an agricultural soil by metagenomics following by two analysis pipelines <br/> <br/>Auteur, co-auteur: Stroobants, Aurore; Lambert, Christrophe; Degrune, Florine; Portetelle, Daniel; Vandenbol, Micheline <br/> <br/>Résumé: On earth, Bacteria are ubiquitous and even present in extreme environments (pH, temperature,…). In soils in particular, bacteria are very abundant (up to 109 cells per gram of soil) but still poorly characterized. Thus, it is of paramount importance to use relevant study and analysis procedures to ensure that the results obtained closely reflect the real-life conditions. In the present work, we analyze the bacterial diversity in the topsoil and below the hardpan in an agricultural soil using the metagenomics approach, with the Ion Torrent PGM sequencer. The soil samples was collected at three depths : 10 cm (topsoil), 25 cm (topsoil above the hardpan) and 45 cm (below the hardpan), in a tilled and a no tilled plot. The taxonomic analysis of the reads obtained are carried out according to two different procedures with the RDP classifier program and with a confidence score threshold of 0 and 0.99. The 0 threshold is used to assign a species to all reads, each read being therefore assigned to its most closest known species. The threshold of 0.99 enables us to focus on reads being assigned to a species with a high degree of confidence. In this case, each read is assigned to the most specific rank having a confidence score higher than 0.99. The bacterial diversity was then compared between the different conditions. Results obtained demonstrate that the bacterial communities were not the same in the two horizons. For example, some classes of Acidobacteria were up to 11 fold more numerous in topsoil while others was until 12 fold more represented below the hardpan. The biomass and the bacterial diversity (Shannon index) were also greatly different between the two depths. http://hdl.handle.net/2268/149046 Titre: Neurogenesis and neural stem cells as therapeutic strategies for Parkinson's disease <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149044 Titre: Neuronal replacement in the ischemic brain <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149043 Titre: Protéines de stress dans le système nerveux <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149041 Titre: HSP25 expression in the nervous system of the adult rat <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149040 Titre: Protection against ischemic injury and cell death by heat shock proteins <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149037 Titre: Role of Heat Shock Proteins (HSP27 and HSP70) in ischemic protection and neuronal plasticity <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149034 Titre: Constitutive expression and induction of the 27kDa heat shock protein in the adult rat nervous system <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe http://hdl.handle.net/2268/149031 Titre: Expression of the 27-kDa heat shock protein following kainic acid-induced status epilepticus in the rat <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe; Armstrong, John N.; Landry, Jacques; Robertson, Harold A.; Currie, R. William http://hdl.handle.net/2268/149027 Titre: Expression of the 27-kDa heat shock protein in adult rat motor neurons <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe; Armstrong, John N.; Robertson, Harold A.; Currie, R. William http://hdl.handle.net/2268/149024 Titre: Hsp2è expression following cortical depolarization in the aduklt rat <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe; Robertson, Harold A.; Currie, R. William http://hdl.handle.net/2268/149022 Titre: Spreading depression induced the expression of the 27-kDa heat shock protein (Hsp27) in astrocytes of the rat cortex <br/> <br/>Auteur, co-auteur: Plumier, Jean-Christophe; Robertson, Harold A.; Currie, R. William http://hdl.handle.net/2268/149020 Titre: expression of HSP70 mRNA and protein in rat hippocampus following heat shock <br/> <br/>Auteur, co-auteur: Krueger, Anne-Marie; Plumier, Jean-Christophe; Armstrong, John A.; Robertson, Harold A.; Currie, R. William http://hdl.handle.net/2268/149019 Titre: Induction of the 27-kDa heat shock protein (Hsp27) and nitric oxide synthase (NOS) in the rat medulla oblongata after vagotomy <br/> <br/>Auteur, co-auteur: Hopkins, David A.; Plumier, Jean-Christophe; Currie, R. William http://hdl.handle.net/2268/149016 Titre: Enhanced susceptibility of focal ischemic in jury in mice lacking prostacyclin receptors <br/> <br/>Auteur, co-auteur: Huang, Zihong; Austin, S.; Salomone, Salvatore; Plumier, Jean-Christophe; Bonventre, J.; Moskowitz, Michael A.