bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheology-based approach for workability characterization of high-performance concrete
Authors: Laskar Aminul Islam , Talukdar Sudip
Published: September 2009

Monitoring of workability is a critical issue since high-performance concrete is susceptible to small changes in mixture proportions that have a direct impact on workability and hardened properties. Test results in fundamental units such as yield stress and plastic viscosity are needed to characterize workability of high-performance concrete. In the present study, rheological properties of concretes with different workability were evaluated with a rheometer fabricated in the laboratory. Yield stress and plastic viscosity measured for various mixes were combined together with shear strain rate to obtain a single parameter, the energy dissipation rate per unit volume, which was used to develop a workability scale.
A hydrodynamic approach to address Yamuna riverbed development in Delhi
Authors: Vijay Ritesh , Sargaonkar Aabha , Gupta Apurba
Published: September 2009

Most critical flood problems occur in urban areas where values at risk are higher and damages tend to be heavier. In the present study, a hydrodynamic simulation of the river Yamuna has been generated under different designated flood flows to delineate the land availability under existing and modified riverbed geometry including channel dredging and riverbed dressing. Flood flows for various return periods, namely once in 10, 25, 50, and 100 years are estimated based on the past 41 years of recorded data using flood frequency analysis. The model set up considered the river stretch of 23 km from the Wazirabad barrage upstream to the Okhla barrage downstream, which includes manmade structures like bridges and barrages. Model calibration is achieved by comparing the water surface elevations with observed data at various downstream gauge stations. The land availability based on submergence scenarios under existing riverbed condition is estimated to be 1147.6, 873.1, and 762.6 ha, respectively, for 10, 50, and 100 year return flood. Various simulations are generated including channel dredging and riverbed dressing to obtain safe height and safe width for dressing the riverbed. The modified river geometry considered channel dredging in 750 to 1350 m width, and riverbed dressing for safe height and width in three levels in various sections. The land availability under this scenario is estimated to be 2197, 1129, and 545 ha for 10, 50, and 100 year return flood, respectively. It is proposed to dress the riverbed by utilizing the material obtained from channel dredging in three levels to maintain the transverse and longitudinal slope, river morphology, and river system. Developmental planning in the riverbed may include utilization of land at three levels for various purposes such as playgrounds, nursery, etc. However, it is suggested that the feasibility study of the project requires detailed engineering including slope stability prior to implementation of the riverbed development.
Aide à la décision multicritère pour la hiérarchisation de tronçons d’assainissement dans le cadre d’une gestion patrimoniale
Authors: Nafi Amir , Werey Caty
Published: September 2009

Les réseaux d’assainissement constituent un patrimoine important qui nécessite une gestion à long terme dans le cadre d’une politique intégrée qui tient compte de l’état des tronçons, de leur environnement et de contraintes budgétaires fortes. Dans cette perspective, une connaissance du patrimoine est nécessaire, à travers la mise en place d’inventaires permettant de collecter des données liées au patrimoine et à son environnement. Dans le cadre de cet article, le patrimoine étudié sera constitué de tronçons d’assainissement non visitables (diamètre inférieur à 1200 mm) pour lesquels un inventaire a été effectué et des données sont disponibles. L’état des tronçons peut être évalué à partir de données d’inspections télévisuelles (ITV) réalisées par caméras robotisées. Ces inspections permettent de décrire l’état des tronçons d’assainissement, mais ne permettent pas de hiérarchiser les tronçons, ni de prendre des décisions de réhabilitation ou de renouvellement. À cet effet, nous proposons d’utiliser la méthodologie développée dans le cadre du projet Français Réhabilitation des réseaux d’assainissement urbains, RERAU (2000–2004), qui propose de mesurer à partir des défauts constatés par ITV des densités de dysfonctionnement. À partir de ces dysfonctionnements, nous utilisons la méthode multicritère Electre-tri pour la mise en place d’une procédure d’affectation des tronçons en catégories selon leur état de détérioration. L’étude a été réalisée sur un échantillon de tronçons d’assainissement en Alsace, France. L’article décrit la mise en place de la démarche et présente les principaux résultats.
Influence des rapports eau/ciment et fines/ciment sur le comportement à l’état durci du béton autoplaçant à base de matériaux locaux algériens
Authors: Bouhamou N. , Belas N. , Mesbah H. , Jauberthie R. , Ouali A. , Mebrouki A.
Published: September 2009

Le présent travail est une seconde étape faisant partie de notre travail de recherche sur l’influence des paramètres de composition sur le comportement des bétons autoplaçants (BAP) à l’état frais et durci. Il concerne l’étude de l’effet des rapports eau sur ciment et fines sur ciment sur le comportement du BAP à l’état durci. Plusieurs essais ont été réalisés tels que l’étalement, la boîte en L, la stabilité au tamis, le ressuage, les résistances mécaniques, le retrait libre (retrait de séchage et retrait endogène) et une étude microstructurale (caractérisation minéralogique, distributions porométriques) afin de comprendre les rôles joués par les différents constituants susceptibles d’entrer dans la formulation d’un BAP à base de matériaux locaux et chercher à mieux cerner les mécanismes qui régissaient les comportements vis-à-vis du retrait. Nous avons mis en évidence le rôle du réseau poreux et de la microstructure des hydrates. Les résultats obtenus offrent de belles perspectives pour optimiser les BAP en Algérie. Notre étude a permis de développer une variété de formulations de bétons autoplaçants répondant aux critères rhéologiques (bonne déformabilité, moins de ressuage, absence de ségrégation, meilleures performances mécaniques).
A simple method to predict flow diversion by louvers
Authors: Rajaratnam N. , Sadeque M. A.F. , Katopodis C.
Published: September 2009

A simple method has been developed to predict the flow division at the louver, based on the experimental finding of Shepherd et al. (2007) that the specific energy of the flow through a diversion structure housing a louver system is approximately constant. Flow through louver slot is expressed using a consolidated contraction coefficient to account for the lumped effect of flow contraction between the louver slats and the approximations of the proposed theoretical model (e.g., constant specific energy, flow direction through the louver slots). A relationship is developed for the consolidated coefficient from the simulation of experimental results obtained from Shepherd et al. (2007). It is observed from the simulation results that the consolidated contraction coefficient is best correlated with the relative width of the bypass. Finally, the use of this simple method is demonstrated using a set of numerical experiments within the range of experimental conditions of the louver system.
Cysteine engineering of actin self-assembly interfaces
Authors: Pengelly Kate , Loncar Ana , Perieteanu Alex A. , Dawson John F.
Published: September 2009

The Holmes model of filamentous actin (F-actin) and recent structural studies suggest specific atomic interactions between F-actin subunits. We tested these interactions through a cysteine-engineering approach with the goal of inhibiting filament formation by introducing chemical groups at sites important for polymerization. We substituted surface amino acids on the actin molecule with cysteine residues and tested the effect of producing these actin mutant proteins in a yeast expression system. The intrinsic folding and polymerization characteristics of the cysteine-engineered actin proteins were measured. The effect of chemical modification of the introduced cysteine residues on the polymerization of the actin mutant proteins was also examined. Modification of cysteine residues with large hydrophobic reagents resulted in polymerization inhibition. We examined the finding that the D288C actin protein does not polymerize under oxidizing conditions and forms protein aggregates when magnesium and EGTA are present. Chemical crosslinking experiments revealed the presence of a lower dimer when only D288C actin was present. When both D288C and A204C actin were present, crosslinking experiments support the proximity of Asp288 on the barbed end of one subunit to Ala204 on the pointed end of a neighboring subunit in the Holmes model of F-actin.
Absence of the major light-harvesting antenna proteins alters the redox properties of photosystem II reaction centres in thechlorina F2mutant of barley
Authors: Krol Marianna , Ivanov Alexander G. , Booij-James Isabelle , Mattoo Autar K. , Sane P. V. , Hüner Norman P.A.
Published: September 2009

Although the chlorina F2 mutant of barley specifically exhibits reduced levels of the major light-harvesting polypeptides associated with photosystem II (PSII), thermoluminescence measurements of photosystem reaction centre photochemistry revealed that S2/S3QB–charge recombinations were shifted to lower temperatures, while the characteristic peak of S2QA–charge recombinations was shifted to higher temperatures compared with wild-type (WT) barley. Thus, we show that the absence of the major light-harvesting polypeptides affects the redox properties of PSII reaction centres. Radiolabeling studies in vivo and in vitro with [32P]orthophosphate or [γ-32P]ATP, respectively, demonstrated that the D1 PSII reaction centre polypeptide is phosphorylated in both the WT and the F2 mutant. In contrast with the radiolabeling results, phosphorylation of D1 and other PSII proteins, although detected in WT barley, was ambiguous in the F2 mutant when the phosphothreonine antibody method of detection was used. Thus, caution must be exercised in the use of commercially available phosphothreonine antibodies to estimate thylakoid polypeptide phosphorylation. Furthermore, in membrano, the D1 polypeptide of the F2 mutant was less susceptible to trypsin treatment than that of WT barley. The role of the light-harvesting complex in modulating the structure and function of the D1 polypeptide of PSII reaction centers is discussed.
Involvement of a disintegrin and metalloproteinase 10 and 17 in shedding of tumor necrosis factor-α
Authors: Hikita Atsuhiko , Tanaka Nobuho , Yamane Shoji , Ikeda Yasuko , Furukawa Hiroshi , Tohma Shigeto , Suzuki Ryuji , Tanaka Sakae , Mitomi Hiroyuki , Fukui Naoshi
Published: September 2009

Tumor necrosis factor-α (TNF-α) is initially synthesized as a membrane-bound protein and converted into a soluble form by proteolytic cleavage. Although a disintegrin and metalloproteinase 17 (ADAM17) is considered to be the primary sheddase for TNF-α, it is not known whether ADAM17 is solely responsible for that process in any type of cells. To identify the TNF-α sheddase(s) in varieties of cells, we performed experiments using a unique screening system and observed that ADAM9, ADAM10, ADAM17, and ADAM19 were capable of cleaving TNF-α. We then performed RNA interference experiments and confirmed that ADAM10 and ADAM17 were in fact involved in TNF-α shedding in 293A cells. In mouse macrophages, ADAM17 was confirmed to be the primary sheddase, but the involvement of ADAM10 was also demonstrated. In NIH3T3 cells, ADAM10 could be more important in the shedding than ADAM17. In mouse vascular endothelial cell line UV♀2, ADAM10 and ADAM17 were equally involved in TNF-α shedding, whereas ADAM17 was a major sheddase in human osteoarthritic chondrocytes. From these observations and others, we concluded that both ADAM10 and ADAM17 can be a TNF-α sheddase and that their significance could be determined by their expression levels and the abundance of tissue inhibitor of metalloproteinases.
Interaction of tRNA with antitumor polyamine analogues
Authors: N’soukpoé-Kossi C. N. , Ahmed Ouameur A. , Thomas T. , Thomas T. J. , Tajmir-Riahi H. A.
Published: September 2009

We studied the interaction between tRNA and three polyamine analogues (1,11-diamino-4,8-diazaundecane·4HCl (333), 3,7,11,15-tetrazaheptadecane·4HCl (BE-333), and 3,7,11,15,19-pentazahenicosane·5HCl (BE-3333)) using FTIR, UV-visible, and CD spectroscopic methods. Spectroscopic evidence showed that polyamine analogues bound tRNA via guanine N7, adenine, uracil O2, and the backbone phosphate (PO2–) groups, while the most reactive sites for biogenic polyamines were guanine N7/O6, adenine N7, uracil O2, and sugar 2′-OH groups as well as the backbone phosphate group. The binding constants of polyamine analogue – tRNA recognition were lower than those of the biogenic polyamine – tRNA complexes, with K333= 2.8 (±0.5) × 104, KBE-333= 3.7 (±0.7) × 104, KBE-3333= 4.0 (±0.9) × 104, Kspm= 8.7 (±0.9) × 105, Kspd= 6.1 (±0.7) × 105, and Kput= 1.0 (±0.3) × 105mol/L. tRNA remained in the A-family conformation; however, it aggregated at high polyamine analogue concentrations.
Probing Alzheimer amyloid peptide aggregation using a cell-free fluorescent protein refolding method
Authors: Arslan Pharhad Eli , Chakrabartty Avijit
Published: September 2009

Fibrillation of the Alzheimer β-amyloid peptide (Aβ) and (or) formation of toxic oligomers are key pathological events in Alzheimer’s disease. Several strategies have been introduced to identify small molecule aggregation inhibitors, and based on these methods, a number of aggregation inhibitors have been identified. However, most of these methods use chemically synthesized Aβ42 peptides, which are difficult to maintain in a monomeric state at neutral pH where anti-aggregation screening is usually carried out. We have developed a cell-free Aβ42 aggregation assay based on fluorescence protein refolding. This assay utilizes nanomolar concentrations of protein. We genetically fused Aβ42 to the N-terminus of vYFP, a variant of of GFP, and expressed and purified the folded fusion protein. The refolding efficiency of Aβ42–vYFP fusion was inversely correlated with the solubility of Aβ42. Using fluorescence to monitor refolding of Aβ42–vYFP, we confirmed that Zn2+binds to Aβ42 and increases its aggregation. The IC50value estimated for Zn binding is 3.03 ± 0.65 µmol/L. We also show that this technique is capable of monitoring the aggregation of chemically synthesized Aβ42.
Labeling and imaging of GLUT4 in live L6 cells with quantum dots
Authors: Wang Xiaoxuan , Qu Feng , Chen Zubin , Liang Tao , Qu Anlian
Published: September 2009

GLUT4 is sequestered in intracellular storage compartments in a basal state and is rapidly translocated to the cell surface in response to insulin stimulation. Regulation of GLUT4 distribution is key for maintaining whole-body glucose homeostasis. To investigate the complicated intracellular movement of GLUT4 vesicles and their interactions with organelles in detail, new probes suitable for long-term tracking of cellular events are required. In this study, we introduce for the first time quantum dots (QDs) as a superior probe into the research of the mechanisms of GLUT4 translocation. QDs are light-emitting semiconductor nanoparticles with unique optical and spectroscopic properties, such as broad absorption, narrow and tunable emission, resistance to photobleaching, strong luminescence, and long luminescent lifetimes. Owing to their remarkable photophysical properties and relatively small size, QDs are emerging as an alternative to conventional dyes for fluorescence-based applications. We have developed a procedure for labeling and imaging GLUT4 in live cells with streptavidin-conjugated quantum dot (QD-SA) and demonstrated that QDs contained in cytoplasm have no obvious negative influence on L6 cells. This study provides a sensitive, nontoxic, long-term imaging platform for observing the dynamics and regulated characteristics of GLUT4 transport.
Novel role for theSaccharomyces cerevisiaeoligopeptide transporter Opt2 in drug detoxificationIn memory of Ghassan Belhadj.
Authors: Aouida Mustapha , Khodami-Pour Ali , Ramotar Dindial
Published: September 2009

Saccharomyces cerevisiae Opt2 is a member of the oligopeptide transporter family that was initially identified to transport tetra- and pentapeptides. Mutants deleted for the OPT2 gene exhibit no growth defects under normal culture conditions. We identified OPT2 from a high-throughput screen that when deleted results in mutants that displayed sensitivity to the anticancer agent bleomycin. The opt2Δ mutant was also reisolated in two additional genome-wide screens designed to identify mutants that are sensitive to the immunosuppressant rapamycin and the divalent metal ion zinc. However, the role of Opt2 in protecting cells against these agents was not investigated. Herein, we show that opt2Δ mutants are also sensitive to a wide variety of toxic agents that are typically detoxified by the vacuoles. Mutants lacking two other related oligopeptide transporters, Opt1 and Ygl114w, showed no significant sensitivities to these drugs, indicating a specific role for Opt2 in drug detoxification. The sensitivities of the opt2Δ mutants were not related to an increased drug uptake but rather to the presence of several small vesicles instead of a functional large vacuole. We propose that Opt2 has a novel function involving the fusion of vesicles to form a mature vacuole.
Exendin-4 exerts its effects through the NGF/p75NTRsystem in diabetic mouse pancreas
Authors: Gezginci-Oktayoglu Selda , Bolkent Sehnaz
Published: September 2009

Glucagon-like peptide-1 (GLP-1) ameliorates the symptoms of diabetes through stimulation of insulin secretion. We have investigated the possible components of cellular mechanism triggered by exendin-4, a potent GLP-1 receptor agonist, in streptozotocin (STZ) induced diabetic mice pancreas. BALB/c male mice were divided into four groups for this investigation. The first group was given citrate buffer only, the second group was administered exendin-4 alone, the third group received STZ, and the fourth group was given both STZ and exendin-4. Exendin-4 (3 µg/kg) was administered by daily subcutaneous injection for 30 days after the animals were rendered diabetic by administration of STZ (200 mg/kg). With exendin-4 treatment on diabetic mice, the following results were noted: (i) exendin-4 suppressed the increase in plasma glucose and inhibited somatostatin expression induced by STZ, (ii) reduction of insulin prevalence was inhibited, while expression of p75 neurotrophin receptor (p75NTR), pancreatic nerve growth factor (NGF), and NGF-positive islet cell prevalence increased, (iii) there were no alterations in the severity of proliferated cell nuclear antigen positive or apoptotic beta cells in pancreatic islets, and (iv) pancreatic catalase, glutathione peroxidase, and superoxide dismutase activities significantly increased. In conclusion, these data suggest that exendin-4 might exert its actions through the NGF/p75NTRsystem and decrease somatostatin expression.
Glycosaminoglycan chains from α5β1integrin are involved in fibronectin-dependent cell migrationDedicated to the memory of Professor Carl P. Dietrich.
Authors: Franco Célia R.C. , Trindade Edvaldo S. , Rocha Hugo A.O. , Bertoni da Silveira Rafael , Paludo Katia Sabrina , Chammas Roger , Veiga Silvio S. , Nader Helena B. , Dietrich Carl P.
Published: September 2009

α5β1integrin from both wild-type CHO cells (CHO-K1) and deficient in proteoglycan biosynthesis (CHO-745) is post-translationally modified by glycosaminoglycan chains. We demonstrated this using [35S]sulfate metabolic labeling of the cells, enzymatic degradation, immunoprecipitation reaction with monoclonal antibody, fluorescence microscopy, and flow cytometry. The α5β1integrin heterodimer is a hybrid proteoglycan containing both chondroitin and heparan sulfate chains. Xyloside inhibition of sulfate incorporation into α5β1integrin also supports that integrin is a proteoglycan. Also, cells grown with xyloside adhered on fibronectin with no alteration in α5β1integrin expression. However, haptotactic motility on fibronectin declined in cells grown with xyloside or chlorate as compared with controls. Thus, α5β1integrin is a proteoglycan and the glycosaminoglycan chains of the integrin influence cell motility on fibronectin. Similar glycosylation of α5β1integrin was observed in other normal and malignant cells, suggesting that this modification is conserved and important in the function of this integrin. Therefore, these glycosaminoglycan chains of α5β1integrin are involved in cellular migration on fibronectin.
A novel phylogenetic group withinThozetella(Chaetosphaeriaceae): a new taxon based on morphology and DNA sequence analyses
Authors: Jeewon R. , Yeung S. Y.Q. , Hyde K. D.
Published: September 2009

A new species, Thozetella pinicola , was isolated from leaf litter of Pinus elliottii Engelm. in Hong Kong. This taxon is described and compared with existing species in the genus. It occurs on the substrate as creamy white sporodochia and has short black conidiophores. Morphological characters are typical of Thozetella and it most closely resembles Thozetella falcata , Thozetella gigantea and Thozetella nivea , but may be distinguished by its distinct microawns and different conidial size. To gain further taxonomic insight into the phylogenetic relationships of our new taxon and its allies, we sequenced and analysed 6 different regions of 3 genes (ribosomal DNA and protein coding genes: RNA polymerase II largest subunit (RBP2) and β-tubulin). Resulting phylogenies are compared with existing morphological information. Molecular data support the relationship between Thozetella species and the Chaetosphaeriaceae (Chaetosphaeriales, Sordariomycetes). In addition, we recovered a new phylogenetic lineage (or group) within the existing phylogenetic framework of Thozetella as previously proposed. In particular, there is a close association between T. pinicola and T. nivea, which is strongly supported. The affinities of these 2 newly sequenced taxa are discussed in light of morphological and molecular characters.
Comparative quantification of Campylobacter jejuni from environmental samples using traditional and molecular biological techniques
Authors: Rothrock Michael J. , Cook Kimberly L. , Bolster Carl H.
Published: September 2009

Campylobacter jejuni is one of the most common causes of gastroenteritis in the world. Given the potential risks to human, animal, and environmental health, the development and optimization of methods to quantify this important pathogen in environmental samples is essential. Two of the most commonly used methods for quantifying C. jejuni are selective plate counting and quantitative real-time PCR (qPCR). Unfortunately, little comparative research has been performed to evaluate the accuracy of these methods for quantification of C. jejuni in aqueous and solid matricies. In this study, the limit of detection and the level of resolution obtained using these 2 methods was evaluated for C. jejuni and compared with that of the common indicator organism Escherichia coli . The use of selective plate count media for quantification of C. jejuni resulted in a 0.7–1.2 log underestimation of cell concentrations, compared with qPCR in both water and column leachate samples, whereas E. coli concentrations were found to be similar with either technique. For C. jejuni, only the qPCR assay accurately measured 2-fold changes in cell concentrations in water samples, whereas concentrations of E. coli were accurately measured regardless of method. Based on these data, qPCR assays were found to be more accurate than selective plate counts for quantification of C. jejuni from environmental samples.
Identification of oligopeptides mimicking the receptor-binding domain of Hantaan virus envelope glycoprotein from a phage-displayed peptide library
Authors: Lü Xin , Yin Wen , Yang Qiaoxin , Lei Yingfeng , Yang Jing , Sun Mengning , Yao Min , Xu Zhikai , Xue Xiaoping
Published: September 2009

Attachment of enveloped viruses to cells is triggered by the receptor-binding domain (RBD) on envelope glycoproteins (GP) binding to receptors located on the cell surface. To date, recognized receptors and RBD of hantaan virus (HTNV) have not been exactly defined. In this study, one monoclonal antibody (MAb) 3G1 possessing high neutralizing activity, which is directed against HTNV envelope glycoprotein G2, was used to determine the crucial motif of RBD. Peptide ligands binding to MAb 3G1 were selected from a 12 amino acid peptide library displayed on filamentous phages. After 3 rounds of selection, the binding capacity between phages and MAb 3G1 was examined byELISA. Afterwards the positive phage clones with high binding activity to MAb 3G1 were chosen and sequenced. The peptide sequences of positive phage clones were compared with that of HTNV 76–118 strain G2. A motif Y/F/WPW(X)HX1–2HY, aligned to the primary sequences of G2 96YPWHTAKCHY105, was identified from the peptide inserts in the 9 positive clones. Positive phages and synthesized peptide containing the motif were bound significantly to virus-susceptible cell (Vero-E6) membranes by ELISA and immunofluorescence assay, respectively. Therefore, the sequence on G2 between amino acid 96 and 105 may be a key motif of HTNV RBD recognized by viral receptors on target cell membranes. Further characterization of the motif would provide useful information in understanding of the cellular entry of HTNV.
Classical swine fever virus Ernsglycoprotein antagonizes induction of interferon-β by double-stranded RNA
Authors: Luo Xuelian , Ling Dawei , Li Ting , Wan Chao , Zhang Chuyu , Pan Zishu
Published: September 2009

Classical swine fever virus (CSFV) is capable of counteracting innate cellular antiviral responses by inhibiting type I interferon (IFN)-α/β induction. A function associated with CSFV Npro, with respect to the inhibition of IFN-β production, has been clearly elucidated. In this study, we explored the role of CSFV Ernsin IFN-β induction by exogenous double-stranded (ds) RNA. Synthetic dsRNA (poly (IC)) was used as an exogenous stimulus to trigger IFN-β induction. CSFV Ernsinhibited IFN-β promoter-driven luciferase activity induced by poly (IC) in different cell lines, and the inhibitory effect was dose-dependent. Moreover, Ernsreduced IFN-β mRNA synthesis and blocked IFN-α/β production induced by poly (IC), suggesting that this inhibition occurs at the transcriptional level. Furthermore, Ernscounteracted poly (IC)-mediated IFN-β induction independent of its ribonuclease activity. In conclusion, CSFV Ernsantagonizes extracellular dsRNA-mediated IFN-β expression. These findings contribute to our understanding of the pathogenesis of CSFV.
Molecular characterization of the pL40 protein inLeptospira interrogans
Authors: Zhao Wei , Chen Chun-Yan , Zhang Xiang-Yan , Lai Wei-Qiang , Hu Bao-Yu , Zhao Guo-Ping , Qin Jin-Hong , Guo Xiao-Kui
Published: September 2009

Leptospirosis is a widespread zoonotic disease caused by pathogenic leptospires. The identification of outer membrane proteins (OMPs) conserved among pathogenic leptospires, which are exposed on the leptospiral surface and expressed during mammalian infection, has become a major focus of leptospirosis research. pL40, a 40 kDa protein coded by the LA3744 gene in Leptospira interrogans , was found to be unique to Leptospira . Triton X-114 fractionation and flow cytometry analyses indicate that pL40 is a component of the leptospiral outer membrane. The conservation of pL40 among Leptospira strains prevalent in China was confirmed by both Western blotting and PCR screening. Furthermore, the pL40 antigen could be recognized by sera from guinea pigs and mice infected with low-passage L. interrogans. These findings indicate that pL40 may serve as a useful serodiagnostic antigen and vaccine candidate for L. interrogans.
Characterization of tetracycline- and ampicillin-resistant Escherichia coli isolated from the feces of feedlot cattle over the feeding period
Authors: Mirzaagha Parasto , Louie Marie , Read Ron R. , Sharma Ranjana , Yanke L. Jay , Topp Edward , McAllister Tim A.
Published: September 2009

The objective of this study was to investigate tetracycline and ampicillin resistance in Escherichia coli isolated from the feces of 50 crossbred steers housed in 5 feedlot pens. The steers were not administered antibiotics over a 246-day feeding period. A total of 216 isolates were selected for further characterization. The E. coli isolates were selected on MacConkey agar or on MacConkey agar amended with ampicillin (50 µg/mL) or tetracycline (4 µg/mL). Pulsed-field gel electrophoresis (PFGE) typing (XbaI digestion), screening against 11 antibiotics, and multiplex PCR for 14 tet and 3 β-lactamase genes were conducted. Prevalence of antimicrobial resistance in E. coli at each sampling day was related both temporally and by pen. Multiplex PCR revealed that tet(B) was most prevalent among tetracycline-resistant isolates, whereas β-lactamase tem1-like was detected mainly in ampicillin-resistant isolates. Our results suggest that antimicrobial resistance in E. coli populations persists over the duration of the feeding period, even in the absence of in-feed antibiotics. Many of the isolates with the same antibiograms had indistinguishable PFGE patterns. Characterization of the factors that influence the nature of this nonselective resistance could provide important information for consideration in the regulation of in-feed antimicrobials for feedlot cattle.
Disruption of the 2-methylcitric acid cycle and evaluation of poly-3-hydroxybutyrate-co-3-hydroxyvalerate biosynthesis suggest alternate catabolic pathways of propionate inBurkholderia sacchari
Authors: Pereira Erica Mendes , Silva-Queiroz Sonia Regina , Cabrera Gomez José Gregório , Silva Luiziana Ferreira
Published: September 2009

The objective of the present work was to evaluate the relevance of the 2-methylcitric acid cycle (2MCC) to the catabolism of propionate in Burkholderia sacchari . Two B. sacchari mutants unable to grow on propionate were obtained: one disrupted in acnM, and the other in acnM and prpC deleted. An operative 2MCC significantly reduces the bacterial ability to incorporate 3-hydroxyvalerate (3HV) into a biodegradable copolyester accumulated from carbohydrates plus propionate. The efficiency of the mutants in converting propionate to 3HV units (Y3HV/prp) increased from 0.09 g·g–1to 0.81–0.96 g·g–1, indicating that acnM and prpC are both essential for growth on propionate. None of the mutations resulted in achievement of the maximum theoretical Y3HV/prp(1.35 g·g–1). When increasing concentrations of propionate were supplied, decreasing values of Y3HV/prpwere observed. The results obtained corroborate the hypothesis of the presence of other propionate catabolic pathways in B. sacchari. The 2MCC would be the more operative pathway, but a second pathway, which remains to be elucidated, would assume more importance under propionate concentrations of 1 g·L–1or higher. The efficiency in converting propionate to 3HV units can be improved by decreasing the propionate concentrations, owing to the role of the 2MCC.
Clonal relationships determined by multilocus sequence typing among enteropathogenicEscherichia coliisolated in Brazil
Authors: Pitondo-Silva André , Minarini Luciene A.R. , Camargo Ilana L.B.C. , Darini Ana Lúcia C.
Published: September 2009

Enteropathogenic Escherichia coli (EPEC) infections are a leading cause of infantile diarrhea in developing nations. Multilocus sequence typing (MLST) characterizes bacterial strains based on the sequences of internal fragments in housekeeping genes. Little is known about strains of EPEC analyzed by MLST from Brazil. In this study, a diverse collection of 29 EPEC strains isolated from patients with diarrhea, admitted to the University Hospital of Ribeirao Preto, was characterized by MLST. Strain analysis demonstrated 22 different sequence types (STs), of which almost half (48%) were new, indicating a high genotype diversity. The 22 STs were divided by eBURST into 12 clonal complexes. It was not possible to correlate typical and atypical EPEC with other strains in the MLST database. This is the first study that analyzed EPEC strains from South America that are included in the E. coli MLST database. Nine (31%) out of 29 strains are part of the CC10 clonal complex, the major clonal complex in the database, which comprises 174 strains and 86 different STs, suggesting that these strains might be the most important intestinal pathogenic E. coli worldwide. Genetic relationships between typical and atypical EPEC, enterohemorrhagic E. coli, and enteroaggregative E. coli strains were not established by MLST.
Detection of a novel bacterium associated with spores of the arbuscular mycorrhizal fungusGigaspora margarita
Authors: Long Liangkun , Yao Qing , Ai Yuncan , Deng Mingrong , Zhu Honghui
Published: September 2009

With PCR-denaturing gradient gel electrophoresis analysis, two bacterial 16S rRNA gene V3 region sequences, 7A and 7B, were detected in association with the crushed spores of the arbuscular mycorrhizal fungus Gigaspora margarita W.N. Becker & I.R. Hall 1976 MAFF520054. DNA sequencing and phylogenetic analysis revealed that 7B was mostly related to the documented cytoplasm endosymbiotic bacterium Candidatus Glomeribacter gigasporarum of G. margarita, but 7A could not be confidently assigned to a known taxon. Further characterization of 7A was conducted by obtaining its almost complete 16S rRNA gene sequence via PCR amplification and sequencing. BLAST search indicates that the 16S rRNA gene sequence did not match any identified species sequences in the GenBank database. Further detection revealed that 7A was also associated with the clean G. margarita MAFF520054 spores that were obtained by the surface-sterilized method or dual culture with Ri T-DNA transformed carrot roots. Many ellipse-shaped or egg-shaped bacterium-like organisms were clustered in layer 3 of the fungal spore wall by transmission electron microscopy observation. Our results indicate that 7A represents a novel bacterial population associated with G. margarita MAFF520054 spores, and its doubtless location (wall or cytoplasm) remains unclear based on the present data.
DNA extraction procedure affects organic-aggregate-attached bacterial community profiles from a shallow eutrophic lake
Authors: Tang Xiangming , Gao Guang , Zhu Liping , Chao Jianying , Qin Boqiang
Published: September 2009

Organic aggregates (OA) in aquatic ecosystems harbour diverse microbial communities. The colonization and growth of OA-attached bacteria are important processes in the degradation and transformation of the particles. The development of efficient and comparative DNA extraction methods is one of the most critical steps in the study of the composition and diversity of OA-attached bacterial communities. To evaluate whether different DNA extraction procedures affect the measurement of bacterial community composition, we compared four in situ lysis procedures using OA from three locations in a shallow eutrophic lake (Lake Taihu, China). The extracted DNA was analyzed using denaturing gradient gel electrophoresis profiles. We found that the choice of DNA extraction protocol had a significant influence on the fingerprints of the OA-attached bacterial community. This was shown not only in the number of bands but also in their relative representation of certain DNA bands. Using the bead-beating DNA extraction method in the presence of hexadecyltrimethylammonium bromide, we found that crude microbial DNA could be extracted efficiently from different OA types. This protocol is reproducible and gives very pure DNA of relatively high molecular mass. More importantly, the protocol provided more representative and informative data on the diversity of OA-attached bacterial communities.
Involvement of RecG in H2O2-induced damage repair in Deinococcus radiodurans
Authors: Wu Yuanyuan , Chen Weiwei , Zhao Ye , Xu Hong , Hua Yuejin
Published: September 2009

Deinococcus radiodurans (ex Raj et al. 1960) Brooks and Murray 1981 is well known for its efficient repair of various types of physically or chemically induced DNA damage caused by ionizing and ultraviolet radiation or H2O2. RecG codes for a helicase that is known to be involved in repairing oxidative damage in other bacterium. In this work, we constructed a DRrecG deletion mutant and investigated its possible role in H2O2-induced damage. The results showed that the deletion of DRrecG resulted in an obvious growth defect and great decrease of radioresistance of D. radiodurans to gamma radiation and H2O2. We also defined the transcriptional profiles of the recG mutant and wild-type strain with and without treatment with H2O2. These results suggested that DRrecG is important for DNA repair during oxidative damage.
Altitudinal distribution of microfungi associated withBetula ermaniileaf litter on Mt. Rishiri, northern Japan
Authors: Osono Takashi , Hirose Dai
Published: September 2009

The altitudinal distribution of microfungi associated with Betula ermanii Cham. leaf litter was investigated on Mt. Rishiri (1719 m), northern Japan. Fallen leaves were collected at five sites of different altitudes (appoximately 300, 600, 900, 1200, and 1500 m above sea level) along a transect on the northern slope of Mt. Rishiri. A total of 35 species were isolated from Betula leaf litter of which 12 occurred frequently and were regarded as dominant microfungi. Species richness, diversity, and equitability of microfungal assemblages were lower at Site 1500 than at the other sites. Similarities in species composition were relatively high among Sites 300, 600, and 900, but similarities between these sites and sites at the higher altitudes (i.e., Sites 1200 and 1500) were relatively low. Similarity of species composition was relatively low between Sites 1200 and 1500. Cluster analysis showed that the 12 major microfungal species were classified into four groups according to their pattern of altitudinal distribution that peaked at Sites 600, 900, 1200, and 1500, respectively. These results suggest that the diversity and species composition of Betula microfungi are sensitive to environmental changes along the altitudinal transect on Mt. Rishiri, and this is especially so at the altitudes higher than approximately 1200 m. This implies that future environmental changes will have impacts on mountainous ecosystems through the changes in diversity and functional aspects of microfungal assemblages.
Influence of arbuscular mycorrhizae on the root system of maize plants under salt stress
Authors: Sheng Min , Tang Ming , Chen Hui , Yang Baowei , Zhang Fengfeng , Huang Yanhui
Published: September 2009

Salt stress has become a severe global problem, and salinity is one of the most important abiotic factors limiting plant growth and yield. It is known that arbuscular mycorrhizal (AM) fungi decrease plant yield losses under salinity. With the aim of determining whether AM inoculation would give an advantage to root development under salt stress, a greenhouse experiment was carried out with AM or without AM fungi. Maize plants were grown in a sand and soil mixture with 5 NaCl levels (0, 0.5, 1.0, 1.5, and 2.0 g/kg dry substrate) for 55 days, following 15 days of nonsaline pretreatment. At all salt levels, mycorrhizal plants had higher dry shoot and root mass, higher root activity, and lower root to shoot ratios than non-mycorrhizal plants. In salt-free soil, root length, root surface area, root volume, and number of root tips and forks were significantly larger in mycorrhizal plants than in non-mycorrhizal plants, whereas, under salt stress, average root diameter and root volume of mycorrhizal plants were larger than those of non-mycorrhizal plants. Regardless of the NaCl level, mycorrhizal plants had lower specific root length, lower percentage of root length in the 0–0.2 mm diameter class, and higher percentage of root length in both the 0.2–0.4 mm and 0.4–0.6 mm diameter classes, which suggests that the root system shows a significant shift towards a thicker root system when maize plants were inoculated with Glomus mosseae (Nicolson & Gerdemann). The results presented here indicate that the improvements in root activity and the coarse root system of mycorrhizal maize may help in alleviating salt stress on the plant.
Comparison of media used to evaluateRhizobium leguminosarumbivarviciaefor phosphate-solubilizing ability
Authors: Xie Jia , Knight J. Diane , Leggett Mary E.
Published: September 2009

Rhizobium leguminosarum is well known for its ability to fix nitrogen (N). In addition, its capacity to solubilize phosphate (Ph) has been receiving attention in recent years. Our ultimate objective was to select a R. leguminosarum bv. viciae isolate with superior Ph-solubilizing ability. The first step was to identify a culture medium that is sensitive and effective in identifying the ability of R. leguminosarum bv. viciae isolates to solubilize Ph. Thirty isolates were evaluated for Ph solubilization in broth and on solid formulations of three media: yeast mannitol extract (YEM), National Botanical Research Institute phosphate nutrient medium (MNBRI), and Pikovskaya phosphate medium (PVK). All media contained 5 g/L CaHPO4as the only phosphorus (P) source. All 30 isolates increased the Ph concentration in liquid cultures, but the amount of Ph released into solution by individual isolates varied from one medium to another. In contrast, only a subset of the 30 isolates solubilized Ph on the solid cultures. Furthermore, some of the isolates that were able to solubilize Ph were only able to do so on a single medium. Regression analysis revealed no relationship between the Ph concentration in the liquid media and the zones of clearing on the solid media (p > 0.05). Although the pH of all of the liquid media dropped after 12 days of growth of the isolates, a relationship between Ph concentration and pH existed only for the MNBRI medium (r2= 0.485, p < 0.001). Increasing the amount of N in the MNBRI medium from 0.1 g/L of (NH4)2SO4to 0.5 g/L of (NH4)2SO4did not affect the amount of Ph in solution, but it profoundly reduced the survival of the R. leguminosarum by approximately 50-fold. Consequently, the surviving bacteria were either more efficient at solubilizing Ph in the high N media or organic acids released from the lysis of the dead cells solubilized the CaHPO4source.
Enhanced enrichment and detection of thermotolerant Campylobacter species from water using the Portable Microbe Enrichment Unit and real-time PCR
Authors: Pitkänen Tarja , Bräcker Juliane , Miettinen Ilkka T. , Heitto Anneli , Pesola Jouni , Hakalehto Elias
Published: September 2009

An enhanced enrichment using the Portable Microbe Enrichment Unit (PMEU) with the microaerobic bubbling of broths was applied for the detection of thermotolerant Campylobacter species from water. This PMEU enrichment was compared with the conventional static enrichment of the international standard ISO 17995:2005. In addition, Campylobacter detection after enrichment using a real-time PCR detection was compared with colony counts. The tests with stressed Campylobacter jejuni cells in drinking water indicated that the PMEU enrichment yielded a significantly higher number of Campylobacter cells in the Bolton broth compared with the conventional static incubation. Application of the real-time PCR technique shortened the Campylobacter detection time. This combination of method modifications can be used for Campylobacter detection from water and adds methodological repertoire for the rapid survey and management of waterborne outbreaks.
In vitro maturation and migration of immature dendritic cells after chemokine receptor 7 transfection
Authors: Xin Hai-ming , Peng Yi-zhi , Yuan Zhi-qiang , Guo Hao
Published: September 2009

Dendritic cells are specialized antigen-presenting cells that regulate immunity and tolerance. Chemokine receptor 7 (CCR7), which is expressed by mature dendritic cells, mediates the migration of the cells to secondary lymphoid organs and thus regulates immune responses. It has been demonstrated that immature dendritic cells can induce immune tolerance, but they do not express CCR7 and cannot migrate to secondary lymphoid organs. We transfected immature dendritic cells with a recombinant adenovirus carrying the CCR7 gene to obtain immature dendritic cells with the ability to migrate. The maturity of the cells was monitored by scanning electron microscopy and flow cytometry. In addition, we assessed the ability of cells to migrate and the function of the cells using in vitro chemotactic and mixed leukocyte reaction assays. The results showed that immature dendritic cells became semi-mature, exhibiting a mild upregulation of co-stimulatory molecular expression and a few dendritic processes. Immunofluorescence assay and Western blotting indicated that CCR7 protein expression increased significantly in immature dendritic cells following CCR7 gene transfection. The in vitro chemotactic assay showed a significantly enhanced ability to migrate in response to CCL19 following CCR7 gene transfection. Moreover, transfected cells showed an enhanced ability to stimulate allogeneic T cell proliferation in vitro, but their ability was significantly weaker than that of mature dendritic cells. Interleukin-10 inhibited the differentiation and maturation of immature dendritic cells. It is concluded that, following CCR7 gene transfection, immature dendritic cells exhibit an enhanced ability to migrate and some of the characteristics of mature cells. Thus, these cells are of potential clinical significance in studies of immune tolerance induction during skin grafting after severe burns.
Epileptic seizure-induced hypertension and its prevention by calcium channel blockers: a real-time study in conscious telemetered rats
Authors: Beig Mirza Irfan , Chandra Ramesh , Talwar Anita , Fahim Mohammad , Katyal Anju
Published: September 2009

Epileptic seizures are accompanied by changes in autonomic function that in turn influence the cardiovascular system (hypertension and bradyarrhythmia). We have studied possible cardioprotective activity (during the ictal state in conscious animals) of valproic acid, nifedipine, and verapamil, alone and in combination, during pentylenetetrazole (PTZ)-induced seizures. Telemetry system was used for recording EEG, blood pressure, and heart rate in conscious, freely moving rats during seizures. We observed that PTZ-induced seizures were accompanied by hypertension and bradyarrhythmia. Pretreatment with valproic acid did not block seizure-induced hypertension and bradyarrhythmia. Nifedipine alone and in combination with valproic acid blocked seizure-induced hypertension and bradyarrhythmia significantly. We also observed that pretreatment with verapamil alone and in combination with valproic acid did not block seizure-induced hypertension and bradyarrhythmia significantly. Our results suggest that pretreatment with nifedipine alone or in combination with valproic acid provides protection against seizure-induced hypertension and bradyarrhythmia.