Littérature scientifique sur le sujet « Glucose oxidase/glucose reaction »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Sommaire
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Glucose oxidase/glucose reaction ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Glucose oxidase/glucose reaction"
1
Nováková, A., L. Schreiberová et I. Schreiber. « Study of dynamics of glucose-glucose oxidase-ferricyanide reaction ». Russian Journal of Physical Chemistry A 85, no 13 (décembre 2011) : 2305–9. http://dx.doi.org/10.1134/s003602441113019x.
Texte intégral
2
Číp, M., L. Schreiberová et I. Schreiber. « Dynamics of the reaction glucose-catalase-glucose oxidase-hydrogen peroxide ». Russian Journal of Physical Chemistry A 85, no 13 (décembre 2011) : 2322–26. http://dx.doi.org/10.1134/s0036024411130061.
Texte intégral
3
Murthy, A. Surya N., et Anita. « Benzoquinone-mediated glucose/glucose oxidase reaction at pyrolytic graphite electrode ». Electroanalysis 5, no 3 (avril 1993) : 265–68. http://dx.doi.org/10.1002/elan.1140050313.
Texte intégral
4
Johnson, Kristin A., Beth A. Kroa et Tony Yourey. « Factors affecting reaction kinetics of glucose oxidase ». Journal of Chemical Education 79, no 1 (janvier 2002) : 74. http://dx.doi.org/10.1021/ed079p74.
Texte intégral
5
Zeng, Ke, Minghui Yang, You-Nian Liu et Avraham Rasooly. « Dual function hollow structured mesoporous Prussian blue mesocrystals for glucose biosensors ». Analytical Methods 10, no 32 (2018) : 3951–57. http://dx.doi.org/10.1039/c8ay01456f.
Texte intégralRésumé :
Dual function hollow structured mesoporous Prussian blue mesocrystals (HMPB) serve both as a scaffold carrier matrix to load the enzyme glucose oxidase and as a redox mediator of H2O2, the by-product of glucose oxidase catalyzed glucose reaction. The red and blue symbols represent glucose oxidase and HMPB, respectively.
6
Hiraishi, H., A. Terano, S. Ota, H. Mutoh, M. Razandi, T. Sugimoto et K. J. Ivey. « Role for iron in reactive oxygen species-mediated cytotoxicity to cultured rat gastric mucosal cells ». American Journal of Physiology-Gastrointestinal and Liver Physiology 260, no 4 (1 avril 1991) : G556—G563. http://dx.doi.org/10.1152/ajpgi.1991.260.4.g556.
Texte intégralRésumé :
The gastric epithelium is exposed to oxygen species that are generated within the lumen. Reactive oxygen species, enzymatically generated, cause injury to cultured rat gastric mucosal cells. Much interest has been focused on the role of iron in producing oxidant-mediated injury to the gastric mucosa, because iron is a catalyst that promotes the production of .OH possibly from O2-. and H2O2 (Haber-Weiss reaction) or from H2O2 alone (Fenton reaction). With the use of an iron chelator and an iron binding protein, we examined the role of iron in producing oxidant-mediated injury to cultured gastric mucosal cells. Reactive oxygen species and H2O2 were generated by hypoxanthine-xanthine oxidase and glucose-glucose oxidase, respectively, in buffer without iron. Pretreatment with deferoxamine diminished hypoxanthine-xanthine oxidase-induced 51Cr release from prelabeled cells, dose dependently. Furthermore, addition of deferoxamine to the reactive oxygen species-generating system also protected against the injury. However, apotransferrin (which binds extracellular iron) failed to protect cells. Pretreatment with .OH scavengers was partially protective. Depletion of glutathione with diethyl maleate enhanced reactive oxygen species-mediated cytolysis; such cytolysis was inhibited by deferoxamine. Deferoxamine also decreased 51Cr release induced by glucose-glucose oxidase. We conclude that intracellular iron plays a crucial role in mediating oxygen radical damage to gastric mucosal cells. The .OH, produced from H2O2 by the iron-catalyzed Fenton reaction, seems to be the main mediator of oxidant-induced cytotoxicity to gastric mucosal cells in vitro.
7
Michael, John R., Boaz A. Markewitz et Donald E. Kohan. « Oxidant stress regulates basal endothelin-1 production by cultured rat pulmonary endothelial cells ». American Journal of Physiology-Lung Cellular and Molecular Physiology 273, no 4 (1 octobre 1997) : L768—L774. http://dx.doi.org/10.1152/ajplung.1997.273.4.l768.
Texte intégralRésumé :
Endothelin-1 (ET-1) is a pluripotent mediator that modulates vascular tone and influences the inflammatory response. Patients with inflammatory lung disorders frequently have elevated circulating ET-1 levels. Because these pathophysiological conditions generate reactive oxygen species that can regulate gene expression, we investigated whether the level of oxidant stress influences ET-1 production in cultured rat pulmonary arterial endothelial cells (RPAEC). Treatment with the antioxidant 1,3-dimethyl-2-thiourea (10 mM) or the iron chelator deferoxamine (1.8 μM) doubles basal ET-1 release. Conversely, exposing cells to H2O2generated by glucose and glucose oxidase (0.1–10 mU/ml) for 4 h causes a concentration-dependent decrease in ET-1 release. This effect occurs at concentrations of glucose oxidase that do not affect [3H]leucine incorporation or specific 51Cr release from RPAEC. Catalase prevents the decrease in ET-1 synthesis caused by glucose and glucose oxidase. Glucose and glucose oxidase decrease not only ET-1 generation but also ET-1 mRNA as assessed by semiquantitative polymerase chain reaction. Our results indicate that changes in oxidative stress can either up- or downregulate basal ET-1 generation by cultured pulmonary endothelial cells.
8
Yee, Ying Chuin, Rokiah Hashim, Ahmad Ramli Mohd Yahya et Yazmin Bustami. « Colorimetric Analysis of Glucose Oxidase-Magnetic Cellulose Nanocrystals (CNCs) for Glucose Detection ». Sensors 19, no 11 (31 mai 2019) : 2511. http://dx.doi.org/10.3390/s19112511.
Texte intégralRésumé :
Glucose oxidase (EC 1.1.3.4) sensors that have been developed and widely used for glucose monitoring have generally relied on electrochemical principle. In this study, the potential use of colorimetric method for glucose detection utilizing glucose oxidase-magnetic cellulose nanocrystals (CNCs) is explored. Magnetic cellulose nanocrystals (magnetic CNCs) were fabricated using iron oxide nanoparticles (IONPs) and cellulose nanocrystals (CNCs) via electrostatic self-assembly technique. Glucose oxidase was successfully immobilized on magnetic CNCs using carbodiimide-coupling reaction. About 33% of GOx was successfully attached on magnetic CNCs, and the affinity of GOx-magnetic CNCs to glucose molecules was slightly higher than free enzymes. Furthermore, immobilization does not affect the specificity of GOx-magnetic CNCs towards glucose and can detect glucose from 0.25 mM to 2.5 mM. Apart from that, GOx-magnetic CNCs stored at 4 °C for 4 weeks retained 70% of its initial activity and can be recycled for at least ten consecutive cycles.
9
Wang, Hong, Yang Yang Liu, Xiao Jing Yao, Yan Li, Ji Yu Wu et Jian Guo Cui. « Research on Glucose Oxidase Biosensor Based on Reverse Iontophoresis ». Advanced Materials Research 641-642 (janvier 2013) : 785–88. http://dx.doi.org/10.4028/www.scientific.net/amr.641-642.785.
Texte intégralRésumé :
Objective: Making a glucose sensor to detect the glucose which is extracted from the tissue fluid on reverse iontophoresis. Method: In the role of the catalysis of glucose oxidase which was fixed in polyethylene oxide gel, the glucose and potassium ferricyanide were change into gluconic acid and potassium ferrocyanide. Then we could get the concentration of glucose by detecting the current which was created by the redox reaction. Results: The glucose sensors could detect the concentration of glucose in the range of 2.2~22mmol/l and have a good linear too. The conformance test results show that the deviation of multiple measurements of the same sensor is less than 2% and the reaction time is less than 1s. Conclusion: The sensors could detect the blood glucose.
10
Zou, Quan, Gong Cheng et Yu Zhang. « Study on electrochemical biosensor based on screen-printed electrode ». Modern Physics Letters B 32, no 34n36 (30 décembre 2018) : 1840061. http://dx.doi.org/10.1142/s0217984918400614.
Texte intégralRésumé :
It is known that redox reaction can take place among the solutions of potassium ferrocyanide (K4[Fe(CN)6]), glucose (C6H[Formula: see text]O6) and glucose oxidase (Glucose Oxidase, GOD). In this work, the method of electrochemical biosensor detection based on screen printed electrode was used to observe the redox reaction among these solutions. The relationship between redox reaction and parameters was studied by examining the effects of concentration and scanning speed of three solutions.
Thèses sur le sujet "Glucose oxidase/glucose reaction"
1
Hooper, Stephanie Elaine. « Development of an Ionically-Assembled On-Column Enzyme Reactor for Capillary Electrophoresis ». Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28190.
Texte intégralRésumé :
This work describes the integration of a separation capillary for capillary electrophoresis (CE) with an on-column enzyme reactor for selective determination of the enzyme substrate. The enzyme reaction occurs during a capillary separation, allowing selective determination of the substrate in complex samples without the need for pre- or post- separation chemical modification of the analyte. The overall goal of this work is to develop a system in which sample introduction, separation of the analyte/substrate from other biological species, enzymatic conversion of the analyte/substrate into a detectable product, and sensitive detection are all included within a single analysis scheme.
Immobilization of the enzyme is achieved by electrostatic assembly of poly(diallydimethylammonium chloride) (PDDA) followed by adsorption of a mixture of the negatively charged enzyme glucose oxidase (GOx) and anionic poly(styrenesulfonate) (PSS). The reaction of glucose with the immobilized glucose oxidase produces H2O2 which migrates the length of the capillary under the influence of electroosmotic flow and is detected amperometrically at the capillary outlet.
The optimal response, kinetics, and stability for the enzyme reactor are determined through characterization of several parameters including the concentration ratio of PSS:GOx, applied separation voltage, and the inner diameter of the separation capillary. Various analyte mixtures containing the substrate and other biological species were evaluated to illustrate selective separation and determination of the substrate from other biomolecules. Optimization of this electrostatically assembled capillary enzyme reactor lead to application of these parameters to similar enzymes such as glutamate oxidase. Future application to similar enzymes like L-amino acid oxidase and possible microfluidic systems is a long-term goal of the system.Ph. D.
2
Botero, Carrizosa Sara C. « Synthesis, Characterization, and Properties of Graphene-Based Hybrids with Cobalt Oxides for Electrochemical Energy Storage and Electrocatalytic Glucose Sensing ». TopSCHOLAR®, 2017. http://digitalcommons.wku.edu/theses/1941.
Texte intégralRésumé :
A library of graphene-based hybrid materials was synthesized as novel hybrid electrochemical electrodes for electrochemical energy conversion and storage devices and electrocatalytical sensing namely enzymeless glucose sensing. The materials used were supercapacitive graphene-family nanomaterials (multilayer graphene-MLG; graphene oxide-GO, chemically reduced GO-rGO and electrochemical reduced GOErGO) and pseudocapacitive nanostructured transition metal oxides including cobalt oxide polymorphs (CoO and Co3O4) and cobalt nanoparticles (CoNP). These were combined through physisorption, electrodeposition, and hydrothermal syntheses approaches. This project was carried out to enhance electrochemical performance and to develop electrocatalytic platforms by tailoring structural properties and desired interfaces. Particularly, electrodeposition and hydrothermal synthesis facilitate chemically-bridged (covalently- and electrostatically- anchored) interfaces and molecular anchoring of the constituents with tunable properties, allowing faster ion transport and increased accessible surface area for ion adsorption. The surface morphology, structure, crystallinity, and lattice vibrations of the hybrid materials were assessed using electron microscopy (scanning and transmission) combined with energy dispersive spectroscopy and selected-area electron diffraction, X-ray diffraction, and micro-Raman Spectroscopy. The electrochemical properties of these electrodes were evaluated in terms of supercapacitor cathodes and enzymeless glucose sensing platforms in various operating modes. They include cyclic voltammetry (CV), ac electrochemical impedance spectroscopy, charging-discharging, and scanning electrochemical microscopy (SECM).
These hybrid samples showed heterogeneous transport behavior determining diffusion coefficient (4⨯10-8 – 6⨯10-6 m2/s) following an increasing order of CoO/MLG < Co3O4/MLG < Co3O4/rGOHT < CoO/ErGO < CoNP/MLG and delivering the maximum specific capacitance 450 F/g for CoO/ErGO and Co3O4/ rGOHT. In agreement with CV properties, these electrodes showed the highest values of low-frequency capacitance and lowest charge-discharge response (0.38 s – 4 s), which were determined from impedance spectroscopy. Additionally, through circuit simulation of experimental impedance data, RC circuit elements were derived. SECM served to investigate electrode/electrolyte interfaces occurring at the solid/liquid interface operating in feedback probe approach and imaging modes while monitoring and mapping the redox probe (re)activity behavior. As expected, the hybrids showed an improved electroactivity as compared to the cobalt oxides by themselves, highlighting the importance of the graphene support. These improvements are facilitated through molecular/chemical bridges obtained by electrodeposition as compared with the physical deposition.
3
Junior, Fadi Antoine Taraboulsi. « Enzimas microbianas na conversão da sacarose em frutose e ácido glicônico usando reatores descontínuo-alimentado e contínuo com membrana ». Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/9/9134/tde-28072010-113005/.
Texte intégralRésumé :
A sacarose é uma matéria-prima em franca expansão de produção no Brasil, seu maior produtor e exportador. Essa molécula pode ser convertida, através de um processo multienzimático, em produtos de maior valor agregado: frutose e ácido glicônico, os quais são importados pelo país, e amplamente utilizados em indústrias químicas, de produção de fármacos e setores alimentícios. Neste estudo, avaliou-se a hidrólise da sacarose pela invertase assim como a conversão da glicose em ácido glicônico, pela ação da glicose oxidase, ambas em processo descontínuo-alimentado. A solução de substrato (64g/L-sacarose; 32g/L-glicose) foi adicionada segundo as seguintes leis: constante, linear crescente, linear decrescente, exponencial crescente e exponencial decrescente. No caso da glicose, foi necessária a utilização de enzima auxiliar, a catalase, para degradar a água oxigenada formada durante a conversão da glicose. Mediante os resultados dos testes com os dois substratos, realizou-se teste de conversão direta da sacarose em frutose e ácido glicônico, utilizando-se invertase, glicose oxidase e catalase em regime descontínuo-alimentado, com alimentação linear decrescente (melhor resultado para ambos os substratos). No procedimento contínuo, alvo principal do trabalho, utilizou-se reator com membrana, da marca MILLIPORE ®, integrando em uma única etapa a conversão catalítica, a separação/concentração do produto e a recuperação do biocatalisador. A temperatura foi controlada por circulação de água, tendo acoplado uma bomba peristáltica (para controlar a vazão de alimentação do substrato) e um sistema de pressurização. O reator operou com membrana de ultrafiltração (corte molecular = 100 kDa) e foi mantido sob agitação constante. Os parâmetros de partida foram, a princípio, fixados de acordo com os valores otimizados no reator descontínuo-alimentado com o emprego simultâneo das enzimas.Sucrose is a commodity largely produced in Brazil and one of the most used and commercialized product in food industry. It can be converted through a multienzyme process in fructose and gluconic acid, which have commercial values higher than sucrose. Both products are imported by Brazil, being largely employed in the chemical, food and pharmaceutical industry. This work dealt with the hydrolysis of sucrose by invertase into fructose and glucose, and the oxidation of glucose to gluconic acid by glucose oxidase and catalase. Catalase was added in order to decompose the hydrogen peroxide an inhibitor of glucose oxidase formed as by-product of the oxidation. Two processes were employed. Fed-batch in which the hydrolysis and oxidation reactions were carried out separately by adding invertase followed by glucose oxidase and catalase was conducted by adding the solution of substrate according to a constant, increasing linear, decreasing linear, increasing exponential or decreasing exponential mode. The best fed-batch performance was attained through the decreasing linear addition of sucrose (64g/L) and glucose (32g/L). Setting this kind of addition and using all enzymes simultaneously, the direct conversion of sucrose to fructose and gluconic acid occurred at a yield of 72%. The continuous process was carried out in a cell-type membrane reactor (membrane cut off = 100 kDa), in which the sucrose conversion was made by using all enzymes simultaneously, leading to a final yield of about 76%
4
Williams, Benedick John Lassetter. « ENDOR spectroscopy of glucose oxidase ». Thesis, Queen Mary, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404900.
Texte intégral
5
Chen, Ting. « The development and application of glucose electrodes based on "wired" glucose oxidase ». Access restricted to users with UT Austin EID UMI Company copy, 2001. http://www.lib.utexas.edu/etd/r/d/2001/c4207.
Texte intégral
6
Lefrançois, Pauline. « Développement d’un microréacteur biomimétique pour l'analyse in situ d'activités enzymatiques par couplage de l’électrochimie et de la microscopie de fluorescence ». Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0759/document.
Texte intégralRésumé :
De nombreuses réactions enzymatiques sont à l’origine de processus physiologiques au sein des organismes vivants. Ces réactions sont basées sur des transferts de protons et d’électrons et con-duisent souvent à la production d’espèces secondaires. Parmi elles, les espèces réactives de l’oxygène et de l’azote (ROS, RNS) présentent un intérêt particulier puisqu’elles jouent un double rôle : d’une part en permettant à l’organisme de réagir à un stress par l’activation de voie de signalisation redox, et d’autre part ces ROS et RNS peuvent causer des dommages tissulaires et être à l’origine de dys-fonctionnement (stress oxydant) au sein de l’organisme. La haute réactivité de ces espèces induit leurs faibles durées de vie (ns-min) et rend l’étude de certaines réactions enzymatiques difficiles en solu-tion. Ce projet de thèse a pour objectif de développer un microréacteur biomimétique pour l’étude d’activités enzymatiques produisant des ROS/RNS. En effet, en confinant une réaction au sein d’un compartiment de taille équivalente à celle d’une cellule (20-100 μm de diamètre), les espèces générées (H2O2, NO•, NO2-) doivent pouvoir être sondées in situ avec une résolution cinétique et quantitative. Des vésicules unilamellaires géantes sont formées en conditions physiologiques et servent de micro-réacteurs pour l’analyse des activités enzymatiques de la glucose oxydase et des NO-synthases. La microscopie de fluorescence permet l’observation des vésicules et le suivi du déclenchement de la réaction assuré par microinjection. Les espèces produites sont ensuite détectées en temps réel par électrochimie afin de déchiffrer à terme les différentes voies enzymatiques des NO-SynthasesEnzymatic reactions are involved in many physiological phenomena in living organisms. These reactions are based on protons and electrons transfers and can lead to the production of by-products. Among them, reactive oxygen and nitrogen species (ROS and RNS) are of great interest as they play a double role: on the one hand by allowing the organism to react to a stress by the activation of signaling redox pathways, and on the other hand, ROS and RNS can cause oxidative damages to tissues ensuing dysfunctions in the organism. The high reactivity of such species induce their short lifetimes (ns-min) and leads to uncertainties when it comes to the study of some enzymatic reactions in bulk. This PhD project aims to develop a biomimetic microreactor for the study of enzymatic ac-tivities producing ROS/RNS. Indeed, by confining a reaction within a cell-sized compartment (20-100 μm diameter), the generated species (H2O2, NO•, NO2-) could be analyzed in situ with a quantita-tive and kinetic resolution. Giant unilamellar vesicles are formed in physiological conditions and are used as microreactors for the monitoring of enzymatic activities of glucose oxidase and NO-synthases. Fluorescence microscopy allows individual vesicle observation and the monitoring of reactions trig-gered by microinjection. Then, released species are detected in real-time by electrochemistry in order to decipher the diverse enzymatic pathways of NO-Synthases
7
Pilkington, Sarah. « Incorporating glucose oxidase activity into amyloid fibrils ». Thesis, University of Canterbury. School of Biological Sciences, 2009. http://hdl.handle.net/10092/4435.
Texte intégralRésumé :
Amyloid fibrils are a misfolded state formed by many proteins when subjected to denaturing conditions. Their constituent amino acids make them an excellent target for enzyme immobilisation and their strength, stability and nanometre size are attractive features for exploitation in the creation of new bionanomaterials. The aim of this thesis was to functionalise amyloid fibrils by conjugation to glucose oxidase (GOD). GOD is a relatively stable glycoprotein that catalyses the oxidation of glucose and the release of hydrogen peroxide. The consumption of glucose can be measured to assess glucose levels, and the release of hydrogen peroxide is cytotoxic to cells and is thus an effective antibacterial agent. Three methods of attachment were used: cross-linking using glutaraldehyde, periodate oxidation of the glycoprotein shell, and cross-linking using glutaraldehyde following deglycosylation. GOD retained activity upon attachment by all three methods. These attachment methods were assessed using electrophoresis, centrifugation, sucrose gradient centrifugation and TEM. Gel electrophoresis indicated a high degree of cross-linking and TEM showed no significant change of fibril morphology upon cross-linking. Centrifugation experiments suggested a non-covalent interaction was occurring between amyloid fibrils and GOD, and a covalent attachment was occurring upon addition of glutaraldehyde. Sucrose gradient centrifugation provided increased separation of cross-linked material compared to other separation methods, and showed greater cross-linking to crystallin amyloid fibrils than insulin fibrils. Cross-linking native GOD using glutaraldehyde was chosen for further experiments, as it was found to be most effective for GOD attachment to amyloid fibrils. The resulting functionalised enzyme scaffold was then incorporated into a model poly(vinyl alcohol) (PVOH) film, to create a new bionanomaterial. The distribution of the functionalised fibrils through the film was characterised using SEM and confocal microscopy, where film components were found to be unevenly dispersed. The antibacterial effect of the functionalised film was then tested on E. coli and the antifungal effect of the film was tested on Fusarium, Rhizopus and Penicillium. Growth of E. coli was inhibited around functionalised film circles, demonstrating the incorporation of GOD antibacterial activity into the PVOH film. However, no growth inhibition of fungal species was observed. This work is of significance as it demonstrates the ability to convert a waste material, bovine lens crystallin, to high value protein nanofibres and incorporate functionality via GOD attachment. The incorporation of the GOD-functionalised amyloid fibrils into PVOH provides an excellent ‘proof of concept’ model for the creation of a new bionanomaterial using a functionalised amyloid fibril scaffold. Future development of this model system has the potential to lead to the production of a novel biomaterial for use in food packaging due to the antimicrobial properties of GOD.
8
Binyamin, Gary Neil. « Glucose electro-oxidizing biofuel cell anodes / ». Digital version:, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p9992752.
Texte intégral
9
Iqbal, Munir. « Studies of the structure and function of glucose oxidase ». Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46836.
Texte intégral
10
Hancock, James. « Organic Phase Entrapment of Glucose Oxidase In Polymeric Nanoparticles ». University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1207860116.
Texte intégralLivres sur le sujet "Glucose oxidase/glucose reaction"
1
Ramakrishnan, Venugopal. Oxidative inactivation of glucose oxidase. Ottawa : National Library of Canada = Bibliothèque nationale du Canada, 1993.
Trouver le texte intégral
2
Atrash, Satea Salem El. Characterisation in vitro of glucose oxidase-modified electrodes designed for neurochemical analysis. Dublin : University College Dublin, 1996.
Trouver le texte intégral
3
Rooney, Oliver Brendan. Glucose polymer dialysis fluid : Cytotoxicity and immune reaction. Manchester : University of Manchester, 1996.
Trouver le texte intégral
4
Nazari, Hamid. Enhancement of operational stability of glucose oxidase by immobilization on nylon. 1998.
Trouver le texte intégral
5
Kantt, Carlos Alberto. Effectiveness of glucose oxidase/catalase for on-board preservation of shrimp. 1991.
Trouver le texte intégral
6
Zilliox, Lindsay, et James W. Russell. Diabetic and Prediabetic Neuropathy. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0115.
Texte intégralRésumé :
Impaired glucose regulation (IGR) constitutes a spectrum of impaired glucose and metabolic regulation that can result in neuropathy. Several different pathways of injury in the diabetic peripheral nervous system that include metabolic dysregulation induced by metabolic syndrome induce oxidative stress, failure of nitric oxide regulation, and dysfunction of certain key signaling pathways. Oxidative stress can directly injure both dorsal route ganglion neurons and axons. Modulation of the nitric oxide system may have detrimental effects on endothelial function and neuronal survival. Reactive oxidative species can alter mitochondrial function, protein and DNA structure, interfere with signaling pathways, and deplete antioxidant defenses. Advanced glycelation end (AGE) products and formation of ROS are activated by and in turn regulate key signal transduction pathways.
7
Litell, John M., et Nathan I. Shapiro. Pathophysiology of septic shock. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0297.
Texte intégralRésumé :
The pathophysiology of sepsis is the result of a dysregulated host response to infection. Interactions between conserved pathogenic signals and host recognition systems initiate a systemic reaction to local infection. Pro- and anti-inflammatory intermediates and associated coagulatory abnormalities lead to altered macrovascular, microvascular, and mitochondrial function. Uncorrected, these processes yield similar patterns of failure in multiple organ systems. Mortality increases with successive organ failures. Although commonly thought to be a manifestation of impaired renal circulation, septic acute kidney injury may be due primarily to non-haemodynamic factors. Pulmonary parenchymal dysfunction in sepsis also contributes to failures in other organ systems. Sepsis involves complex alterations in myocardial function, vascular tone, and capillary integrity, which are mediated by elevated concentrations of inflammatory cytokines, inducible nitric oxide, and reactive oxygen species, among others. Gut hypomotility and translocation of enteric flora likely contribute to a persistent inflammatory response. This perpetuates the pathophysiological pattern of sepsis, and can lead to the delayed onset of these features in patients with other types of critical illness. The neurological manifestations of sepsis include acquired delirium, which is also probably due to circulatory and inflammatory abnormalities, as well as alterations in cerebral amino acid metabolism. Critical illness-related corticosteroid insufficiency and derangements in glucose metabolism are among the endocrine abnormalities commonly seen in septic patients. Restoration of homeostasis requires early haemodynamic resuscitation and aggressive infectious source control.
Chapitres de livres sur le sujet "Glucose oxidase/glucose reaction"
1
Laurell, T., L. Rosengren et J. Drott. « A Micromachined Glucose Oxidase Enzyme Reactor ». Dans Micro Total Analysis Systems, 227–31. Dordrecht : Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0161-5_26.
Texte intégral
2
das Neves, Luiz Carlos Martins, et Michele Vitolo. « Use of Glucose Oxidase in a Membrane Reactor for Gluconic Acid Production ». Dans Applied Biochemistry and Biotecnology, 161–70. Totowa, NJ : Humana Press, 2007. http://dx.doi.org/10.1007/978-1-60327-181-3_15.
Texte intégral
3
Wong, Dominic W. S. « Glucose Oxidase ». Dans Food Enzymes, 308–20. Boston, MA : Springer US, 1995. http://dx.doi.org/10.1007/978-1-4757-2349-6_10.
Texte intégral
4
Schomburg, Dietmar, et Dörte Stephan. « Glucose oxidase ». Dans Enzyme Handbook 10, 360–66. Berlin, Heidelberg : Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-57756-7_100.
Texte intégral
5
Stellmach, Bruno. « Glucose-Oxidase ». Dans Bestimmungsmethoden Enzyme, 127–34. Heidelberg : Steinkopff, 1988. http://dx.doi.org/10.1007/978-3-642-93668-5_17.
Texte intégral
6
Bährle-Rapp, Marina. « Glucose Oxidase ». Dans Springer Lexikon Kosmetik und Körperpflege, 225. Berlin, Heidelberg : Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_4291.
Texte intégral
7
Sharma, Atul, Swapnil Tiwari et Jean Louis Marty. « Glucose Oxidase-Mimicking Nanozymes ». Dans Nanozymes, 75–96. Boca Raton : CRC Press, 2021. http://dx.doi.org/10.1201/9781003109228-5.
Texte intégral
8
Kumar, Vijay, et Kiran Dip Gill. « Estimation of Blood Glucose Levels by Glucose Oxidase Method ». Dans Basic Concepts in Clinical Biochemistry : A Practical Guide, 57–60. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-8186-6_13.
Texte intégral
9
Sun, Zhisheng, et Hiroyasu Tachikawa. « Polypyrrole Film Electrode Incorporating Glucose Oxidase ». Dans ACS Symposium Series, 134–49. Washington, DC : American Chemical Society, 1992. http://dx.doi.org/10.1021/bk-1992-0487.ch011.
Texte intégral
10
Wang, Hongwei, Qiaolin Lang, Bo Liang et Aihua Liu. « Electrochemical Glucose Biosensor Based on Glucose Oxidase Displayed on Yeast Surface ». Dans Methods in Molecular Biology, 233–43. New York, NY : Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2748-7_13.
Texte intégralActes de conférences sur le sujet "Glucose oxidase/glucose reaction"
1
Číp, Martin, Lenka Schreiberová et Igor Schreiber. « Dynamics of the Catalase – Glucose Oxidase Oscillatory Reaction ». Dans 14th Asia Pacific Confederation of Chemical Engineering Congress. Singapore : Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-1445-1_736.
Texte intégral
2
Suthar, Kamlesh J., Muralidhar K. Ghantasala et Derrick C. Mancini. « Simulation of Hydrogel Responsiveness to Blood Glucose ». Dans ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3167.
Texte intégralRésumé :
This paper presents the results of our fully coupled, two-dimensional (2D) simulation of the swelling behavior of glucose-sensitive hydrogels at a constant glucose level with change in the surrounding pH. The model consists of a system of glucose-sensitive hydrogel and ionic fluid as a solvent. The hydrogel consists of two enzymes: glucose-oxidase and catalase, which are immobilized on the polymeric network. The surrounding solvent has certain level of glucose. The diffusion of glucose from a solvent and its reaction within the hydrogel are simulated using the Nernst-Planck equation. The local electrical charge is calculated by the Poisson’s equation, and deformation of the hydrogel is determined by the mechanical field equation. These equations are fully coupled and simulations are performed for varying pH and glucose concentrations. The glucose concentration was taken at 7.7mM (140mg/mL) and the pH is varied from 6.8 to 7.4. As glucose reacts with oxygen, gluconic acid is produced in the presence of glucose-oxidase. The formation of gluconic acid within the gel results in protonation and thereby causes the hydrogel expansion. The glucose level in the surrounding solution limits diffusion in the hydrogel. As the surrounding solution pH increases the available fixed charged for ionization increases, which results in an increase in maximum equilibrium swelling and gluconic acid as a product of the reaction. The gluconic acid production was found to be proportional to the change in pH. The gluconic acid decreases the internal pH of the hydrogel, which ultimately reduced the deformation of the gel.
3
Grebennikova, Olga, Aloeksandrina Sulman et Valentina Matveeva. « SYNTHESIS OF MAGNETICALLY SEPARATED BIOCATALYTIC SYSTEMS ». Dans 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022/6.1/s25.16.
Texte intégralRésumé :
The use of magnetic nanoparticles in biocatalysis, due to their unique properties, such as controlled particle size, large surface area, and ease of separating them and the reaction mixture by applying an external magnetic field, makes it possible to reuse enzymes immobilized on magnetic nanoparticles for catalytic processes. In this work, horseradish root peroxidase was immobilized on Fe3O4 magnetic nanoparticles. The carrier surface was modified and activated before enzyme immobilization using 3- aminopropyltriethoxysilane and glutaraldehyde. Testing of biocatalytic systems was carried out in the oxidation reaction of 2,2'-azino-bis-(3-ethylbenzthiozolin-6-sulfonic acid) diammonium salt with hydrogen peroxide. The immobilized enzyme showed high efficiency and stability compared to the native enzyme. Also, in the work, the joint immobilization of peroxidase and glucose oxidase on magnetically attached carriers was studied. Enzymes were immobilized on Fe3O4 magnetic nanoparticles and SiO2. Optimal conditions (temperature, pH) were selected for all biocatalytic systems.
4
Preethichandra, D. M. G., E. M. I. Mala Ekanayake et K. Kaneto. « Characteristics of glucose biosensors with glucose oxidase deposited under high electric field ». Dans 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC). IEEE, 2012. http://dx.doi.org/10.1109/i2mtc.2012.6229587.
Texte intégral
5
Xu, G. Q., J. Lv, Z. X. Zheng et Y. C. Wu. « Polypyrrole (PPy) nanowire arrays entrapped with glucose oxidase biosensor for glucose detection ». Dans 2012 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS). IEEE, 2012. http://dx.doi.org/10.1109/nems.2012.6196803.
Texte intégral
6
Ooe, Katsutoshi, Yasutaro Hamamoto et Yoshiaki Hirano. « Evaluation of MOSFET-type glucose sensor using platinum electrode with glucose oxidase ». Dans Smart Materials, Nano-, and Micro-Smart Systems, sous la direction de Dan V. Nicolau. SPIE, 2005. http://dx.doi.org/10.1117/12.582346.
Texte intégral
7
BLIN, J. L., R. BLETA, M. J. STEBE et C. CARTERET. « ENTRAPMENT OF GLUCOSE OXIDASE INTO MESOSTRUCTURED SILICA ». Dans Proceedings of the 5th International Symposium. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812779168_0072.
Texte intégral
8
Pepłowski, Andrzej, Daniel Janczak et Małgorzata Jakubowska. « Stabilization of glucose-oxidase in the graphene paste for screen-printed glucose biosensor ». Dans XXXVI Symposium on Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments (Wilga 2015), sous la direction de Ryszard S. Romaniuk. SPIE, 2015. http://dx.doi.org/10.1117/12.2205830.
Texte intégral
9
Kojima, K., H. Nasu, M. Shimomura et S. Miyauchi. « An interfering factor in the glucose sensing system with polypyrrole / glucose oxidase membrane ». Dans International Conference on Science and Technology of Synthetic Metals. IEEE, 1994. http://dx.doi.org/10.1109/stsm.1994.836026.
Texte intégral
10
Ekanayake, E. M. I. Mala, D. M. G. Preethichandra et K. Kaneto. « Enhanced Adsorption of Glucose Oxidase by Introducing Artificial Porosity into Polypyrrole Based Glucose Biosensors ». Dans 2007 IEEE Instrumentation and Measurement Technology Conference. IEEE, 2007. http://dx.doi.org/10.1109/imtc.2007.378998.
Texte intégralRapports d'organisations sur le sujet "Glucose oxidase/glucose reaction"
1
Borch, Thomas, Yitzhak Hadar et Tamara Polubesova. Environmental fate of antiepileptic drugs and their metabolites : Biodegradation, complexation, and photodegradation. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7597927.bard.
Texte intégralRésumé :
Many pharmaceutical compounds are active at very low doses, and a portion of them regularly enters municipal sewage systems and wastewater-treatment plants following use, where they often do not fully degrade. Two such compounds, CBZ and LTG, have been detected in wastewater effluents, surface waters, drinking water, and irrigation water, where they pose a risk to the environment and the food supply. These compounds are expected to interact with organic matter in the environment, but little is known about the effect of such interactions on their environmental fate and transport. The original objectives of our research, as defined in the approved proposal, were to: Determine the rates, mechanisms and products of photodegradation of LTG, CBZ and selected metabolites in waters exposed to near UV light, and the influence of DOM type and binding processes on photodegradation. Determine the potential and pathways for biodegradation of LTG, CBZ and selected metabolites using a white rot fungus (Pleurotusostreatus) and ADP, and reveal the effect of DOM complexation on these processes. Reveal the major mechanisms of binding of LTG, CBZ and selected metabolites to DOM and soil in the presence of DOM, and evaluate the effect of this binding on their photodegradation and/or biodegradation. We determined that LTG undergoes relatively slow photodegradation when exposed to UV light, and that pH affects each of LTG’s ability to absorb UV light, the efficiency of the resulting reaction, and the identities of LTG’sphotoproducts (t½ = 230 to 500 h during summer at latitude 40 °N). We observed that LTG’sphotodegradation is enhanced in the presence of DOM, and hypothesized that LTG undergoes direct reactions with DOM components through nucleophilic substitution reactions. In combination, these data suggest that LTG’s fate and transport in surface waters are controlled by environmental conditions that vary with time and location, potentially affecting the environment and irrigation waters. We determined that P. ostreatusgrows faster in a rich liquid medium (glucose peptone) than on a natural lignocellulosic substrate (cotton stalks) under SSF conditions, but that the overall CBZ removal rate was similar in both media. Different and more varied transformation products formed in the solid state culture, and we hypothesized that CBZ degradation would proceed further when P. ostreatusand the ᵉⁿᶻʸᵐᵃᵗⁱᶜ ᵖʳᵒᶠⁱˡᵉ ʷᵉʳᵉ ᵗᵘⁿᵉᵈ ᵗᵒ ˡⁱᵍⁿⁱⁿ ᵈᵉᵍʳᵃᵈᵃᵗⁱᵒⁿ. ᵂᵉ ᵒᵇˢᵉʳᵛᵉᵈ ¹⁴C⁻Cᴼ2 ʳᵉˡᵉᵃˢᵉ ʷʰᵉⁿ ¹⁴C⁻ᶜᵃʳᵇᵒⁿʸˡ⁻ labeled CBZ was used as the substrate in the solid state culture (17.4% of the initial radioactivity after 63 days of incubation), but could not conclude that mineralization had occurred. In comparison, we determined that LTG does not degrade in agricultural soils irrigated with treated wastewater, but that P. ostreatusremoves up to 70% of LTG in a glucose peptone medium. We detected various metabolites, including N-oxides and glycosides, but are still working to determine the degradation pathway. In combination, these data suggest that P. ostreatuscould be an innovative and effective tool for CBZ and LTG remediation in the environment and in wastewater used for irrigation. In batch experiments, we determined that the sorption of LTG, CBZ and selected metabolites to agricultural soils was governed mainly by SOM levels. In lysimeter experiments, we also observed LTG and CBZ accumulation in top soil layers enriched with organic matter. However, we detected CBZ and one of its metabolites in rain-fed wheat previously irrigated with treated wastewater, suggesting that their sorption was reversible, and indicating the potential for plant uptake and leaching. Finally, we used macroscale analyses (including adsorption/desorption trials and resin-based separations) with molecular- level characterization by FT-ICR MS to demonstrate the adsorptive fractionation of DOM from composted biosolids by mineral soil. This suggests that changes in soil and organic matter types will influence the extent of LTG and CBZ sorption to agricultural soils, as well as the potential for plant uptake and leaching.
2
Bennett, Alan B., Arthur Schaffer et David Granot. Genetic and Biochemical Characterization of Fructose Accumulation : A Strategy to Improve Fruit Quality. United States Department of Agriculture, juin 2000. http://dx.doi.org/10.32747/2000.7571353.bard.
Texte intégralRésumé :
The goal of the research project was to evaluate the potential to genetically modify or engineer carbohydrate metabolism in tomato fruit to enhance levels of fructose, a sugar with nearly twice the sweetness value of other sugars. The specific research objectives to achieve that goal were to: 1. Establish the inheritance of a fructose-accumulating trait identified in F1 hybrids of an inferspecific cross between L. hirsutum XL. esculentum and identify linked molecular markers to facilitate its introgression into tomato cultivars. This objective was completed with the genetic data indicating a single major gene, termed Fgr (Fructose glucose ratio), that controlled the partitioning of hexose in the mature fruit. Molecular markers for the gene, were developed to aid introgression of this gene into cultivated tomato. In addition, a second major gene encoding fructokinase 2 (FK2) was found to be a determinant of the fructose to glucose ratio in fruit. The relationship between FK2 and Fgr is epistatic with a combined synergistic effect of the two hirsutum-derived genes on fructose/glucose ratios. 2. Characterize the metabolic and transport properties responsible for high fructose/glucose ratios in fructose-accumulating genotypes. The effect of both the Fgr and FK2 genes on the developmental accumulation of hexoses was studied in a wide range of genetic backgrounds. In all backgrounds the trait is a developmental one and that the increase in fructose to glucose ratio occurs at the breaker stage of fruit development. The following enzymes were assayed, none of which showed differences between genotypes, at either the breaker or ripe stage: invertase, sucrose synthase, FK1, FK2, hexokinase, PGI and PGM. The lack of effect of the FK2 gene on fructokinase activity is surprising and at present we have no explanation for the phenomenon. However, the hirsutum derived Fgr allele was associated with significantly lower levels of phosphorylated glucose, G1c-1-P and G1c-6-P and concomitantly higher levels of the phosphorylated fructose, Fru-6-P, in both the breaker and ripe stage. This suggests a significant role for the isomerase reaction. 3. Develop and implement molecular genetic strategies for the production of transgenic plants with altered levels of enzymes that potentially control fructose/glucose ratios in fruit. This objective focused on manipulating hexokinase and fructokinase expression in transgenic plants. Two highly divergent cDNA clones (Frk1 and Frk2), encoding fructokinase (EC 2.7.1.4), were isolated from tomato (Lycopersicon esculentum) and a potato fructokinase cDNA clone was obtained from Dr. Howard Davies. Following expression in yeast, each fructokinase was identified to code for one of the tomato or potato fructokinase isoforms Transgenic tomato plants were generated with the fructokinase cDNA clone in both sense and antisense orientations and the effect of the gene on tomato plants is currently being studied.
3
Noga, Edward J., Ramy R. Avtalion et Michael Levy. Comparison of the Immune Response of Striped Bass and Hybrid Bass. United States Department of Agriculture, août 1993. http://dx.doi.org/10.32747/1993.7568749.bard.
Texte intégralRésumé :
We developed methods for examining the pathophysical response of striped bass and hybrid bass to various forms of stress. This involved development of techniques for the measurement of lysozyme, mitogen blastogenesis, mixed lymphocyte reaction, and oxidative burst, which are important general indicators of systemic immune function. We also examined local immune defenses (epithelial integrity), as well as homeostatic indicators in blood, including osmotic balance and glucose. Acute stress resulted in significant perturbations in a number of parameters, including glucose, electrolytes, osmolarity, lysozyme, and mixed lymphocyte reaction. Most significantly, acute confinement stress resulted in severe damage to the epidermal epithelium, as indicated by the rapid (within 2 hr) development of erosions and ulcerations on various fins. There were significant differences in the resting levels of some immune functions between striped bass and hybrid bass, including response to mitogens in the leukocyte blastogenesis test. Our studies also revealed that there were significant differences in how striped bass and hybrid bass respond to stress, with striped bass being much more severely affected by stress than the hybrid. This was reflected in more severe changes in glucose, cortisol dynamics, and plasma lysozyme. Most significantly, striped bass developed more severe idiopathic skin ulceration after stress, which may be a major reason why this fish is so prone to develop opportunistic bacterial and fungal infections after stress. Hybrid bass injected with equine serum albumin developed a typical humoral immune response, with peak antibody production 28 days after primary immunization. Fish that were exposed to a chronic stress after a primary immunization showed almost complete inhibition of antibody production.
4
Hochman, Ayala, Thomas Nash III et Pamela Padgett. Physiological and Biochemical Characterization of the Effects of Oxidant Air Pollutants, Ozone and Gas-phase Nitric Acid, on Plants and Lichens for their Use as Early Warning Biomonitors of these Air Pollutants. United States Department of Agriculture, janvier 2011. http://dx.doi.org/10.32747/2011.7697115.bard.
Texte intégralRésumé :
Introduction. Ozone and related oxidants are regarded as the most important phytotoxic air pollutant in many parts of the western world. A previously unrecognized component of smog, nitric acid, may have even greater deleterious effects on plants either by itself or by augmenting ozone injury. The effects of ozone on plants are well characterized with respect to structural and physiological changes, but very little is known about the biochemical changes in plants and lichens exposed to ozone and/or HNO3. Objectives.To compare and contrast the responses of crop plants and lichens to dry deposition of HNO3 and O3., separately, and combined in order to assess our working hypothesis that lichens respond to air pollution faster than plants. Lichens are most suitable for use as biomonitors because they offer a live-organism-based system that does not require maintenance and can be attached to any site, without the need for man-made technical support systems. Original Immediate aims To expose the tobacco (Nicotiana tabacum L.) cultivar Bel-W3 that is ozone supersensitive and the ozone sensitive red kidney bean (Phaseolusvulgaris) and the lichen Ramalinamenziesii to controlled HNO3 and O3 fumigations and combined and to follow the resulting structural, physiological and biochemical changes, with special reference to reactive oxygen species related parameters. Revised. Due to technical problems and time limitations we studied the lichen Ramalinamenziesii and two cultivar of tobacco: Bel-W3 that is ozone supersensitive and a resistant cultivar, which were exposed to HNO3 and O3 alone (not combined). Methodology. Plants and lichens were exposed in fumigation experiments to HNO3 and O3, in constantly stirred tank reactors and the resulting structural, physiological and biochemical changes were analyzed. Results. Lichens. Exposure of Ramalinamenziesiito HNO3 resulted in cell membrane damage that was evident by 14 days and continues to worsen by 28 days. Chlorophyll, photosynthesis and respiration all declined significantly in HNO3 treatments, with the toxic effects increasing with dosage. In contrast, O3 fumigations of R. menziesii showed no significant negative effects with no differences in the above response variables between high, moderate and low levels of fumigations. There was a gradual decrease in catalase activity with increased levels of HNO3. The activity of glutathione reductase dropped to 20% in thalli exposed to low HNO3 but increased with its increase. Glucose 6-phosphate dehydrogenase activity increase by 20% with low levels of the pollutants but decreased with its increase. Tobacco. After 3 weeks of exposure of the sensitive tobacco cultivar to ozone there were visible symptoms of toxicity, but no danmage was evident in the tolerant cultivar. Neither cultivar showed any visible symptoms after exposure to HNO3.In tobacco fumigated with O3, there was a significant decrease in maximum photosynthetic CO2 assimilation and stomatal conductance at high levels of the pollutant, while changes in mesophyll conductance were not significant. However, under HNO3 fumigation there was a significant increase in mesophyll conductance at low and high HNO3 levels while changes in maximum photosynthetic CO2 assimilation and stomatal conductance were not significant. We could not detect any activity of the antioxidant enzymes in the fumigated tobacco leaves. This is in spite of the fact that we were able to assay the enzymes in tobacco leaves grown in Israel. Conclusions. This project generated novel data, and potentially applicable to agriculture, on the differential response of lichens and tobacco to HNO3 and O3 pollutants. However, due to experimental problems and time limitation discussed in the body of the report, our data do not justify yet application for a full, 4-year grant. We hope that in the future we shall conduct more experiments related to our objectives, which will serve as a basis for a larger scale project to explore the possibility of using lichens and/or plants for biomonitoring of ozone and nitric acid air pollution.
5
Shenker, Moshe, Paul R. Bloom, Abraham Shaviv, Adina Paytan, Barbara J. Cade-Menun, Yona Chen et Jorge Tarchitzky. Fate of Phosphorus Originated from Treated Wastewater and Biosolids in Soils : Speciation, Transport, and Accumulation. United States Department of Agriculture, juin 2011. http://dx.doi.org/10.32747/2011.7697103.bard.
Texte intégralRésumé :
Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.
6
Sionov, Edward, Nancy Keller et Shiri Barad-Kotler. Mechanisms governing the global regulation of mycotoxin production and pathogenicity by Penicillium expansum in postharvest fruits. United States Department of Agriculture, janvier 2017. http://dx.doi.org/10.32747/2017.7604292.bard.
Texte intégralRésumé :
The original objectives of the study, as defined in the approved proposal, are: To characterize the relationship of CreA and LaeA in regulation of P T production To understand how PacC modulates P. expansumpathogenicity on apples To examine if other secondary metabolites are involved in virulence or P. expansumfitness To identify the signaling pathways leading to PAT synthesis Penicilliumexpansum, the causal agent of blue mould rot, is a critical health concern because of the production of the mycotoxinpatulin (PAT) in colonized apple fruit tissue. Although PAT is produced by many Penicilliumspecies, the factors activating its biosynthesis were not clear. This research focused on host and fungal mechanisms of activation of LaeA (the global regulator of secondary metabolism), PacC (the global pH modulator) and CreA (the global carbon catabolite regulator) on PAT synthesis with intention to establish P. expansumas the model system for understanding mycotoxin synthesis in fruits. The overall goal of this proposal is to identify critical host and pathogen factors that mechanistically modulate P. expansumgenes and pathways to control activation of PAT production and virulence in host. Several fungal factors have been correlated with disease development in apples, including the production of PAT, acidification of apple tissue by the fungus, sugar content and the global regulator of secondary metabolism and development, LaeA. An increase in sucrose molarity in the culture medium from 15 to 175 mM negatively regulated laeAexpression and PAT accumulation, but, conversely, increased creAexpression, leading to the hypothesis that CreA could be involved in P. expansumPAT biosynthesis and virulence, possibly through the negative regulation of LaeA. We found evidence for CreAtranscriptional regulation of laeA, but this was not correlated with PAT production either in vitro or in vivo, thus suggesting that CreA regulation of PAT is independent of LaeA. Our finding that sucrose, a key ingredient of apple fruit, regulates PAT synthesis, probably through suppression of laeAexpression, suggests a potential interaction between CreA and LaeA, which may offer control therapies for future study. We have also identified that in addition to PAT gene cluster, CreA regulates other secondary metabolite clusters, including citrinin, andrastin, roquefortine and communesins, during pathogenesis or during normal fungal growth. Following creation of P. expansumpacCknockout strain, we investigated the involvement of the global pH regulator PacC in fungal pathogenicity. We demonstrated that disruption of the pH signaling transcription factor PacC significantly decreased the virulence of P. expansumon deciduous fruits. This phenotype is associated with an impairment in fungal growth, decreased accumulation of gluconic acid and reduced synthesis of pectolytic enzymes. We showed that glucose oxidase- encoding gene, which is essential for gluconic acid production and acidification during fruit colonization, was significantly down regulated in the ΔPepacCmutant, suggesting that gox is PacC- responsive gene. We have provided evidence that deletion of goxgene in P. expansumled to a reduction in virulence toward apple fruits, further indicating that GOX is a virulence factor of P. expansum, and its expression is regulated by PacC. It is also clear from the present data that PacC in P. expansumis a key factor for the biosynthesis of secondary metabolites, such as PAT. On the basis of RNA-sequencing (RNA-seq) analysis and physiological experimentation, the P. expansumΔlaeA, ΔcreAand ΔpacCmutants were unable to successfully colonize apples for a multitude of potential mechanisms including, on the pathogen side, a decreased ability to produce proteolytic enzymes and to acidify the environment and impaired carbon/nitrogen metabolism and, on the host side, an increase in the oxidative defence pathways. Our study defines these global regulatory factors and their downstream signalling pathways as promising targets for the development of strategies to fight against this post-harvest pathogen.