bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction and characterization of a bacterial artificial chromosome (BAC) library of hexaploid wheat (Triticum aestivumL.) and validation of genome coverage using locus-specific primers
Authors: Nilmalgoda Sasanda D , Cloutier Sylvie , Walichnowski Andrzej Z
Published: October 2003

A BAC library of hexaploid wheat was constructed using the spring wheat cultivar Triticum aestivum L. 'Glenlea'. Fresh shoot tissue from 7- to 10-day-old seedlings was used to obtain HMW DNA. The library was constructed using the HindIII site of pIndigoBAC-5 and the BamHI site of pIndigoBAC-5 and pECBAC1. A total of 12 ligations were used to construct the entire library, which contains over 650 000 clones. Ninety-six percent of the clones had inserts. The insert size ranged from 5 to 189 kb with an average of 79 kb. The entire library was gridded onto 24 high-density filters using a 5 × 5 array. A subset of these membranes was hybridized with two intergenic chloroplast probes and the percentage of clones containing chloroplast DNA (cpDNA) was calculated to be 2.2%. The genome coverage was estimated to be 3.1 × haploid genome equivalents, giving a 95.3% probability of identifying a clone corresponding to any wheat DNA sequence. BAC pools were constructed and screened using markers targeting the Glu-B1 locus (1BL), the hardness loci (5AS, 5BS, 5DS), the leaf rust resistance locus Lr1 (5DL), and the major fusarium head blight QTL locus located on 3BS. These markers were either locus-specific amplicons or microsatellites. A total of 49 BAC clones were identified for 14 markers giving an average of 3.5 clones/marker, thereby corroborating the estimated 3.1× genome coverage. An example using the gene encoding the HMW glutenin Bx7 is illustrated.Key words: BAC library, BAC pools, hexaploid wheat, locus-specific primers, HMW glutenin.
Development and characterization of chloroplast microsatellite markers inMacaranga(Euphorbiaceae)
Authors: Vogel Miriam , Bänfer Gudrun , Moog Ute , Weising Kurt
Published: October 2003

As part of our study on the phylogeography of the ant-plant genus Macaranga, we have screened for polymorphic regions in the chloroplast genome. Initially, ten universal PCR primer pairs targeted at chloroplast microsatellite loci were applied to a small set of specimens, covering various taxonomic levels from intrafamilial to intraspecific. Eight primer pairs produced PCR fragments that behaved as single and discrete bands on agarose gels. The five most promising candidate pairs were further analysed with an extended set of DNA templates, and PCR products were separated on sequencing gels. The number of size variants per locus varied from two to eight, combining into 17 haplotypes among 29 Macaranga accessions from 10 species. Comparative sequencing demonstrated that microsatellites were responsible for the observed size variation at three of five loci, whereas variation at the other loci was caused by larger insertions and (or) deletions (indels). In addition to poly(A) and poly(T) repeats, which are typically found in chloroplast DNA, we also identified a variable (CT)nrepeat, with n = 4 to n = 8. Sequencing revealed three examples of size homoplasy, one of which was caused by a single base substitution that raised the actual number of haplotypes to 18. Relationships between haplotypes were assessed by phenetic analyses of size variants and by constructing a parsimony network based on sequence variation. For both types of analysis, the distribution of haplotypes correlated with geographically circumscribed regions rather than with taxonomic boundaries.Key words: chloroplast microsatellites, ccmp primers, Macaranga, haplotype network, interspecific gene flow.
Analytical modeling of masonry load-bearing walls
Authors: Liu Yi , Dawe J L
Published: October 2003

An analytical technique was developed and encoded for computer application to study the behaviour of concrete masonry load-bearing walls under various loading conditions. Both geometrical and material nonlinearities to account for the moment magnification effect and the degradation of material stiffness are included in the development. Effects of vertical reinforcing steel, masonry tensile cracking, and compressive crushing are included directly in the momentcurvature relationship, which is used in the determination of element stiffnesses at successive load increments. A parametric study was conducted following verification of the analytical model by comparing results with experimental test data. Effective flexural rigidity (EIeff) values at failure were obtained analytically and compared with values suggested in the Canadian masonry code CSA-S304.1-M94. It was concluded that CSA-S304.1-M94 tends to underestimate EIeff values for reinforced walls and thus leads to a conservative design over a range of parameters. Based on approximately 500 computer model tests, a lower bound bilinear limit for the effective rigidity of reinforced masonry walls was established. This limit is believed to provide an accurate and realistic estimate of EIeff.Key words: walls, load bearing, masonry, analytical, nonlinear, rigidity, stressstrain, momentcurvature.
Developing geographic information systems platforms for multijurisdictional transportation analyses: framework and techniques for spatial data sharing
Authors: Han Kai , Minty Scott , Clayton Alan
Published: October 2003

Geographic information systems (GISs) have been presented as a powerful analysing tool for civil engineers to help their decision-making processes. Building GIS platforms for transportation analysis involving multiple jurisdictions has been challenging, however, because of the complexity and difficulty associated with conducting data sharing and ensuring spatial data interoperability among GISs for transportation (GIS-T) data sets. In the context of western Canadian urban and rural areas, this paper investigates the issues related to GIS-T data sharing, establishes a conceptual framework, develops techniques supporting the framework by solving recurring data-sharing problems, and constructs a number of GIS-T platforms facilitating comprehensive multijurisdictional transportation analyses. In addition, based on the knowledge gained through solving real-world problems, the authors propose an open GIS-T platform consisting of a series of customized base maps, each being tailored to suit the needs of individual application and, as a whole, linked together by interoperability to better support transportation applications.Key words: transportation engineering analysis, GIS, GIS-T, spatial data, interoperability, integration, data sharing.
Cost optimization of concrete bridge infrastructure
Authors: Hassanain Mostafa A , Loov Robert E
Published: October 2003

Recent surveys have indicated that between 30% and 40% of all bridges in North America are in various states of deterioration. Funding is limited owing to the existence of other deficient components of the transportation infrastructure. It is clear, therefore, that the return on the available funding needs to be maximized. This paper presents a review of publications on cost optimization of concrete bridge components and systems and then continues with a review of the state-of-the-art in life-cycle cost (LCC) analysis and design of concrete bridges. The main objective of the paper is to encourage bridge engineers to move towards the increased use of advanced analysis and design optimization methods.Key words: bridge, concrete, cost, high-performance concrete, infrastructure, life-cycle cost, optimization, prestressed girders, reliability.
Influence of effective parameters of non-orthogonal smeared crack approach in seismic response of concrete arch dams
Authors: Espandar Radin , Lotfi Vahid , Razaqpur Ghani
Published: October 2003

A rigorous and relatively efficient algorithm based on the non-orthogonal smeared crack approach is coded in a special finite element program to study the seismic response of arch dams. The formulation is briefly presented. The 130 m high Shahid Rajaee arch dam in Iran subjected to the Friuli-Tolmezzo earthquake is selected to present a practical application of the technique. Under the same geometry and loading conditions, six nonlinear analyses with different parameters are performed, and the results are compared with each other and a linear case. The varied parameters include secant and elastic unloadingreloading options, threshold angle, and tensile strength of the material. It is concluded that the non-orthogonal smeared crack approach can redistribute the state of stresses and produces a more realistic profile of stresses in the dam. A drift in the crest displacements forms the prominent characteristics of the cracking behavior. The results also suggest that the dam can suffer significant cracking during a strong earthquake and still remain stable. Moreover, the influences of the mentioned parameters in the seismic response of the dam are comprehensively discussed.Key words: nonlinear dynamic analysis, concrete arch dam, smeared crack approach.
Une méthode prédictive non biaisée et géoréférencée d'estimation des dommages résidentiels d'inondation
Authors: Leclerc Michel , Secretan Yves , Heniche Mourad , Ouarda Taha B.M.J , Marion Joëlle
Published: October 2003

Flood risk management for residences requires an economical analysis involving the mean annual damage by floods, taking into account the whole range of probability of floods and the cost of projected fluvial enhancements and measures, taking also into account the residual level of risk. Efficient methods are therefore necessary to estimate these risk values. The proposed approach is of a "distributed" type; it involves numerical modeling for estimating "residential submersion depth", a variable, which explains most of the direct damages to residences. The method relies on an individualized georeferenced definition of each residence. Measured submersion data and the compensations obtained from the huge Saguenay flood in 1996 (Ville de Laterrière) were used to build empirical laws based on submersion. Four distinct relationships were established: residences with or without a basement and valued below or above $50,000 each were assigned a specific relationship. With these relationships, direct residential damages in Laterrière were assessed by using only simulation results at the georeferenced position of sector residences as input. It was then possible to evaluate the total amount of direct home damages in Laterrière.Key words: flood, risk, damage rating curves, Saguenay floods, numerical modeling, predictive model, georeference, geographic information system.
Évaluation de la résistance à la fatigue des enrobés bitumineux fondée sur l'évolution de l'endommagement du matériau en cours d'essai : aspects fondamentaux et application à l'enrobé à matrice de pierre
Authors: Perraton Daniel , Baaj Hassan , Benedetto Hervé Di , Paradis Michel
Published: October 2003

Fatigue of bituminous asphalts is one of the main types of pavement destruction. This phenomenon was studied extensively in Europe (RILEM) and in the United States (SHRP). There are no standardized tests in Quebec to assess asphalt fatigue resistance. In France, a new approach based on the determination of damage rates due to fatigue has been developed for a tensioncompression test on asphalt core samples to study their fatigue strength. This paper presents a summary of the knowledge on asphalt fatigue. Damage rate analyses, developed by the DGCB (Département de Génie Civil et du Bâtiment) of the ENTPE at Lyon, is detailed and applied to stone matrix asphalt (SMA). Results show the validity of the approach by damage and the good fatigue damage strength of the SMA.Key words: bituminous asphalts, fatigue, complex module, damage, stone matrix asphalts (SMA), viscoelasticity, mechanical properties of bituminous asphalts.[Journal Translation]
Translocation of transcription regulators into the nucleus during granulocyte commitment of HL-60 cells
Authors: Navakauskiene Ruta , Kulyte Agné , Treigyte Grazina , Gineitis Arunas , Magnusson Karl-Eric
Published: October 2003

Expression of transcription factors required for lineage commitment of differentiating cells (C/EBPβ and c-Myb) and for survival of differentiated cells (STATs and NFκB) was examined in the HL-60 cell line. Differentiation was induced by treating the cells with retinoic acid. c-Myb expression in the nucleus restored at the precommitment stage (18 h) what concurred with the highest nuclear level of C/EBPβ, which suggests a combinatorial interaction of these transcription factors in the granulocytic signalling pathway. Expression of STAT5a and STAT5b varied during differentiation, whereas no significant changes were seen in STAT3 levels. Increased cytosolic level of NFκB p65 during precommitment and commitment stages of granulocytic differentiation coincided with augmentation of the STAT5a protein level, which could be evidence of their possible cooperation during granulocytic-lineage commitment of HL-60 cells. Our results suggest that the studied transcription factors cooperatively promote signalling in the differentiating promyelocytic HL-60 cell line in response to retinoic acid.Key words: C/EBP, Myb, STAT, NFκB, phosphorylation.
Differential expression of Akt, PPARγ, and PGC-1 during hibernation in bats
Authors: Eddy Sean F , Storey Kenneth B
Published: October 2003

The effects of hibernation on the expression of Akt (protein kinase B), the peroxisome proliferator-activated receptor gamma isoform (PPARγ), and the PPARγ coactivator PGC-1 were assessed in seven tissues of the little brown bat, Myotis lucifugus. Western blotting revealed that the levels of active phosphorylated Akt were strongly reduced in brain, kidney, liver, and white adipose during torpor as compared with aroused animals and that total Akt protein was also reduced in white adipose during torpor. By contrast, both total and phospho-Akt were elevated in brown adipose tissue, the thermogenic organ. PPARγ and PGC-1 levels showed parallel changes in all organs. Both were strongly suppressed in brain, but levels increased significantly in all other organs during hibernation (except for PGC-1 in heart). Reduced Akt activity is consistent with a probable reduced insulin response during torpor that facilitates the mobilization of lipid reserves for fuel supply and is further supported by increased gene expression of enzymes and proteins involved in lipid catabolism under the stimulation of enhanced PPARγ and PGC-1 levels.Key words: Myotis lucifugus, mammalian hibernation, lipid metabolism in torpor, protein kinase B, peroxisome proliferator-activated receptor gamma, PPARγ coactivator.
Effect of fetal hemoglobin-stimulating medicines on the interaction of DNA and protein of important erythroid regulatory elements
Authors: Ji Xin-jun , Liu De-pei , Xu Dong-dong , Li Lei , Liang Chih-chuan
Published: October 2003

β-Thalassemia is the most common single gene disorder in the world, which is caused by the imbalance between α-globin chain and β-globin chain synthesis. Several medicines, such as 5-azacytidine, hydroxyurea, cytarabine, vinblatine, butyrate, and myleran, have been shown to be able to reactivate γ-globin chain synthesis during the adult stage, and some of them (5-azacytidine, hydroxyurea, myleran, and butyrate) have been used clinically to treat thalas semia and sickle cell disease. Much research efforts are focusing on the determination of the underlying mechanisms of medicine action. In this experiment, as an effort to probe the underlying mechanism of medicine action, we used ligation-mediated polymerase chain reaction and in vivo footprinting methods to study the DNA-protein interaction at critical erythroid regulatory elements after hydroxyurea or myleran administration to mice. Our results showed that the patterns of in vivo footprints at both the hypersensitive site 2 of the locus control region and the β-globin gene promoter were changed after medicine treatment. We proposed based on these results that the medicines' administration might result in a change in the interaction between trans-acting factors and cis-acting elements at these regions. These changes might influence the assembly of the transcription complex and, lastly, influence the expression of the β-globin gene.Key words: hydroxyurea, in vivo footprinting, ligation-mediated PCR, LCR, β-globin.
A simple formulation of the saturation current density in heavily doped emitters
Authors: Zouari A , Arab A Ben
Published: October 2003

In a non-uniformly and heavily doped emitter region of a bipolar transistor, the continuity equation and the minority-current equation cannot be solved exactly in closed form. This paper shows that the calculation of minority-carrier current density can be calculated by a simple approach. This approach is based on the average value of the equilibrium hole density p0, diffusion constant Dp, and lifetime τp of minority carriers and leads to two coupled differential equations of the first order. These equations can be solved easily and can give a simple expression for the current density. Three definitions of the average values of p0, Dp, and τp are used and lead to three expressions for the emitter current density. The latter is identical to the one established by Rinaldi using another mathematical analysis and gives very accurate results for a shallow emitter (W < 1 µm), irrespective of the range peak doping level N(W) and surface-recombination velocity S. On the other hand, the other two expressions lead also to accurate results for the current density depending on the value of the surface-recombination velocity, but cannot be used when N(W) is greater than 1020 cm3 and W is superior to 0.1 µm. PACS Nos.: 72.10.d, 72.20.i
A three-dimensional numerical simulation of sulfate transport and redistribution
Authors: Spiridonov V , Curic M
Published: October 2003

We have utilized a relatively sophisticated dynamic cloud model combined with standard bulk-parameterized microphysics and simple sulfur chemistry to explore the impact of deep convection on modification and transport of a suite of pollutants. Two base run simulation parameters are used to initialize the cloud-chemistry model. The simulation of the 6 July 1995 case, with continental polluted field initialization, has revealed that a convective storm generates strong vertical transport of gases and particulate compounds from the planetary boundary layer (PBL) to the upper troposphere (UT), perturbation of aerosol physical and chemical properties, modification of pollutant concentration, and change of the spatial distributions of chemical species. The early formation of precipitation and enhanced scavenging contributed to a registration of approximately 2.5 times the concentration of sulfate in the precipitation near the surface than in the air found at this level. The Spring case numerical experiment on 3 April 2000 with a chemical background taken from Macedonia, provided insight into the potential influence of the long-range transport of atmospheric pollutants and ascertained quantitativequalitative information about processes by which acidic species are incorporated into precipitation. The model-computed parameters are in good agreement with observation. The average equivalent cloud water pH and rainwater pH when the higher acid precipitation occurs are about 5.0 and 4.5, respectively. The results from a number of sensitivity tests of cloud chemistry of the physical processes for the continental nonpolluted and continental polluted environments, indicate that nucleation and impact scavenging of aerosols account for between 20%24% of the total sulfur mass removed by wet deposition. Liquid-phase oxidation contributes about 20%28% of the sulfur content in precipitation. It means that neglecting liquid-phase oxidation when considering the chemistry in these clouds may lead to underestimates of about 20%28% in sulfate wet deposition. Neglect of the ice phase when considering the chemistry in continental nonpolluted and continental polluted clouds may lead to overestimates of about 112%130% of the total sulfur mass removed by wet deposition. The assumption of Henry's law equilibrium for those types of clouds gives an overestimation of about 100%120%, respectively. PACS Nos.: 51.10.+y, 92.60.Sz
Composition d'équilibre des plasmas de H2, O2 et N2 hors équilibre thermique
Authors: Koalaga Z
Published: October 2003

We study the evolution of the chemical species in off-thermal equilibrium H2, O2, and N2 plasmas, using both methods of maximisation of entropy and minimisation of Gibbs free energy. These gases are simple and used in electric arc cutting techniques in oil, air, or compressed air and in the arc lamination cutting technique. The study of the plasmas from these gases is an important step in understanding the complex physical processes in the CxHyOzNt type of plasmas. Our numerical calculations cover cases from 5000 to 30 000 K at pressure from 0.1-1 MPa. Comparing the results from the two methods shows that the composition of the equilibrium plasma is strongly influenced by the choice of the hypotheses on the internal temperatures. In the light of experimental measures of internal temperatures reported in the literature, we carry out an analysis of the theoretical hypothesis used herein. [Journal translation]
Magnetohydrodynamic flow near the edge of a rotating disk
Authors: El-Mistikawy T MA , Attia H A
Published: October 2003

The flow of a viscous incompressible electrically conducting fluid due to the rotation of an insulated disk of finite radius is considered. The motion is steady; the disk having uniform angular speed about its axis, parallel to which a magnetic field is applied. In the hydrodynamic case, the flow near the edge of the disk is known to develop into a double-deck structure at the limit of an infinite Reynolds number Re. That the same structure is applicable to the magnetohydrodynamic problem, when the magnetic interaction number β is fixed or diminishing, is a simple extension. More interestingly, it is shown here that the double-deck structure is also applicable when β is growing indefinitely, provided that β3 << Re and the flow variables are properly scaled. PACS No.: 45.65.+a
Detecting resonant states in γd π0d
Authors: Ridener, Jr. F L , Dressler E T
Published: October 2003

The angular distribution function for γd [Formula: see text] π0d scattering is calculated. A method for recognizing the presence of intermediate resonances and their angular momentum is given. As discussed, a measurement of this angular distribution allows for the determination of both the parity of these resonances and their transition amplitudes. PACS No.: 25.20.Lj
Incorporation of epitope-tagged viral σ3 proteins to reovirus virions
Authors: Rouault Étienne , Lemay Guy
Published: October 2003

Tagging of viral capsid proteins is a powerful tool to study viral assembly; it also raises the possibility of using viral particles to present exogenous epitopes in vaccination or gene therapy strategies. The ability of reoviruses to induce strong mucosal immune response and their large host range and low pathogenicity in humans are some of the advantages of using reoviruses in such applications. In the present study, the feasibility of introducing foreign epitopes, "tags", to the σ3 protein, a major component of the reovirus outer capsid, was investigated. Among eight different positions, the amino-terminal end of the protein appeared as the best location to insert exogenous sequences. Additional amino acids at this position do not preclude interaction with the µ1 protein, the other major constituent of the viral outer capsid, but strongly interfere with µ1 to µ1C cleavage. Nevertheless, the tagged σ3 protein was still incorporated to virions upon recoating of infectious subviral particles to which authentic σ3 protein was removed by proteolysis, indicating that µ1 cleavage is not a prerequisite for outer capsid assembly. The recently published structure of the σ3-µ1 complex suggests that the amino-terminally inserted epitope could be exposed at the outer surface of viral particles.Key words: reovirus, recombinant viruses, epitope tagging, vaccination vectors, virus assembly.
Mechanisms of cadmium resistance in anaerobic bacterial enrichments degrading pentachlorophenol
Authors: Kamashwaran S R , Crawford Don L
Published: October 2003

The mechanisms of heavy-metal resistance used by adapted sulfidogenic and methanogenic enrichments degrading pentachlorophenol in the presence of cadmium (Cd) were studied. The enrichment cultures adapted to and readily tolerated bioavailable Cd concentrations up to 50 ppm while degrading an equal concentration of pentachlorophenol. Both cultures removed >95% of the Cd from solution. Transmission electron micrographs revealed (i) the presence of electron-dense particles surrounding the cells in the sulfidogenic enrichments and (ii) the unusual clumping of cells and the presence of an exopolymer in the methanogenic enrichments. Energy dispersive X-ray analysis showed that the sulfidogenic enrichments removed Cd by extracellular precipitation of cadmium sulfide, while the methanogenic enrichment culture removed Cd by extracellular sequestration of Cd into the exopolymer.Key words: cadmium, pentachlorophenol, sulfidogenic, methanogenic, resistance.
Shifts in community composition provide a mechanism for maintenance of activity of soil yeasts in the presence of elevated copper levels
Authors: Cornelissen S , Botha A , Conradie W J , Wolfaardt G M
Published: October 2003

Soil dilution plates were prepared from different soil samples using a solid synthetic selective medium containing (i) glucose as carbon source, (ii) thymine as nitrogen source, (iii) vitamins, (iv) minerals, and (v) chloramphenicol as antibacterial agent. Using the Diazonium Blue B colour reaction, it was found that both ascomycetous and basidiomycetous yeasts were able to grow on this medium. Subsequently, the medium was used to enumerate yeasts in soil microcosms prepared from four different soil samples, which were experimentally treated with the fungicide copper oxychloride, resulting in copper (Cu) concentrations of up to 1000 ppm. The selective medium supplemented with 32 ppm of Cu was used to enumerate Cu-resistant yeasts in the microcosms. The results showed that the addition of Cu at concentrations [Formula: see text]~1000 ppm did not have a significant effect on total number of yeasts in the soil. Furthermore, it was found that Cu-resistant yeasts were present in all the soil samples, regardless of the amount of Cu that the soil was challenged with. At the end of the incubation period, yeasts in the microcosms with zero and ~1000 ppm of additional Cu were enumerated, isolated, and identified with sequence analyses of the D1/D2 600650 bp region of the large subunit of ribosomal DNA. Hymenomycetous species dominated in the control soil, while higher numbers of the urediniomycetous species were found in the soil that received Cu. These observations suggest that urediniomycetous yeasts may play an important role in re-establishing overall microbial activity in soils, following perturbations, such as the addition of Cu-based fungicides.Key words: copper, heavy metals, soil, yeasts.
The infection process of Colletotrichum graminicola and relative aggressiveness on four turfgrass species
Authors: Khan A , Hsiang T
Published: October 2003

Detached 3-week-old leaves of Agrostis palustris, Lolium perenne, Poa annua, and Poa pratensis were inoculated with conidial suspensions of two isolates of Colletotrichum graminicola obtained from A. palustris. Inoculated leaves were incubated at 23 °C under high relative humidity (>95%). The infection process was investigated by light microscopy from 2 to 168 h after inoculation (AI). Spore germination was observed within 2 h AI, appressoria within 6 h AI, and penetration pores within 8 h AI on all four hosts. Infection hyphae were observed inside epidermal cells within 24 h AI on all four hosts, but significantly greater infection was observed in A. palustris and P. annua than in L. perenne or P. pratensis at both 96 and 120 h AI. Acervuli appeared on leaves of A. palustris at 72 h AI and on L. perenne at 96 h AI but were not found on either P. annua or P. pratensis during the first 168 h AI. The infection process was similar to that reported for C. graminicola from other hosts; however, disease development of the two isolates of C. graminicola from A. palustris was faster or fungal growth more extensive on detached leaf tissue of A. palustris than on other turfgrass species tested.Key words: annual bluegrass, anthracnose, creeping bentgrass.
Identification and use of actinomycetes for enhanced nodulation of soybean co-inoculated with Bradyrhizobium japonicum
Authors: Gregor A K , Klubek B , Varsa E C
Published: October 2003

The utilization of actinomycetes as potential soybean (Glycine max (L.)) co-inoculants was evaluated. Soil samples from Carbondale and Belleville, Ill., were used to inoculate pre-germinated soybean plants to determine antibiotic sensitivity in the native Bradyrhizobium japonicum population. Sensitivity was in the order kanamycin > tetracycline > oxytetracycline > rifampicin > neomycin. Antagonism by five actinomycete cultures toward seven test strains of B. japonicum was also assessed. The ranking average inhibition (across all seven B. japonicum strains) by these actino mycetes was Streptomyces kanamyceticus = Streptomyces coeruleoprunus > Streptomyces rimosus > Streptomyces sp. > Amy colatopsis mediterranei. Ten antibiotic combinations were used to isolate antibiotic-resistant mutants of B. japonicum I-110 and 3I1B-110 via successive cycles of mutation. Eighty-one antibiotic-resistant strains were isolated and tested for symbiotic competency; nine of which were selected for further characterization in a greenhouse pot study. Few differences in nodule number were caused by these treatments. Nodule occupancy varied from 0% to 18.3% when antibiotic-resistant strains of B. japonicum were used as the sole inoculants. However, when three mutant strains of B. japonicum were co-inoculated with S. kanamyceticus, significant increases in nodule occupancy (up to 55%) occurred. Increases in shoot nitrogen composition (27.1%40.9%) were also caused by co-inoculation with S. kanamyceticus. Key words: Bradyrhizobium japonicum, Streptomyces kanamyceticus, indigenous bradyrhizobia, co-inoculation, nodule occupancy.
Molecular variability of sunflower downy mildew,Plasmopara halstedii, from different continents
Authors: Roeckel-Drevet P , Tourvieille J , Gulya T J , Charmet G , Nicolas P , Labrouhe D Tourvieille de
Published: October 2003

Downy mildew of sunflower (Helianthus annuus L.), caused by the pathogen Plasmopara halstedii, is a potentially devastating disease. Seventy-seven isolates of P. halstedii collected in twelve countries from four continents were investigated for RAPD polymorphism with 21 primers. The study led to a binary matrix, which was subjected to various complementary analyses. This is the first report on the international genetic diversity of the pathogen. Similarity indices ranged from 89% to 100%. Neither a consensus unweighted pair group method with arithmetic means (UPGMA) tree constructed after bootstrap resampling of markers nor a principal component analysis based on distance matrix revealed very consistent clusterings of the isolates, and groups did not fit race or geographical origins. Phylogenies were probably obscured by limited diversity. Analysis of molecular variance (AMOVA) and Nei's genetic diversity statistics gave similar conclusions. Most of the genetic diversity was attributable to individual differences. The most differentiated races also had the lowest within-diversity indices, which suggest that they appeared recently with strong bottleneck effects. Our analyses suggest that this pathogen is probably homothallic or has an asexual mode of reproduction and that gene flow among countries can occur through commercial exchanges. Knowledge of the downy mildew populations' structure at the international level will help to devise strategies for controlling this potentially devastating disease.Key words: RAPD, Helianthus annuus, genetic diversity, plant pathogen.
Microbial ecology ofBacillusthuringiensis: fecal populations recovered from wildlife in Korea
Authors: Lee Dong-Hyun , Cha In Hwan , Woo Doo Sung , Ohba Michio
Published: October 2003

A total of 34 fecal samples, collected from 14 species of wild mammals in Korea, were examined for the occurrence of Bacillus thuringiensis. The organism was detected in 18 (53%) samples. Among the three food-habit groups, herbivorous animals yielded the highest frequency (69%) of samples positive for B. thuringiensis, followed by omnivorous animals (50%). Of the six fecal samples from carnivorous animals, only one sample contained B. thurin giensis. Among 527 isolates belonging to the Bacillus cereus  B. thuringiensis group, 43 (8%) were assigned to B. thurin giensis on the basis of the formation of parasporal inclusions. Of the 43 isolates, 13 were serologically allocated to the nine H-antigenic serotypes: H3ad (serovar sumiyoshiensis), H15 (dakota), H17/27 (tohokuensis/ mexicanensis), H19 (tochigiensis), H21 (colmeri), H29 (amagiensis), H31/49 (toguchini/muju), H42 (jinghongiensis), and H44 (higo). Other isolates were untestable or untypable by the 55 reference H antisera available. Insecticidal activity was associated with 23% of the fecal populations: three isolates killed larvae of the silkworm, Bombyx mori (Lepidoptera), and seven exhibited larvicidal activity against the mosquito, Aedes aegypti (Diptera). There was no larvicidal activity against the three lepidopterous insects: Plutella xylostella, Spodoptera exigua, and Spodoptera litura. The overall results suggest that wild animals in Korea are in contact with naturally occurring B. thuringiensis at high frequencies through the daily food intake of plants.Key words: Bacillus thuringiensis, fecal population, wild animal, herbivore, H serotyping, insecticidal activity.
Virulence ofCandida albicansmutants toward larvalGalleria mellonella(Insecta, Lepidoptera, Galleridae)
Authors: Dunphy Gary B , Oberholzer Ursula , Whiteway Malcolm , Zakarian Robert J , Boomer Iian
Published: October 2003

Culture medium affected the virulence of a strain of Candida albicans toward Galleria mellonella larvae, but the yeast growth rates in yeast extract  peptone  dextrose broth and synthetic Galleria serum were not correlated with yeast virulence. Virulent C. albicans grew rapidly in larval serum, whereas, it limited nodulation and continued development in vivo, producing toxins that damaged the hemocytes and fat body. Nonpathogenic yeast-phase cells grew slowly in larval serum but induced extensively melanized nodules in vivo and developed no further. There was no discernible relationship in 14 exo-enzymes between the virulent and avirulent yeast strains and virulence. The avirulent myosin-I-defective yeast cells were rapidly removed from the hemolymph in vivo because of lysozyme-mediated yeast agglutination and the possible binding of the yeast cells by lysozyme and apolipophorin-III. Both lysozyme and apolipophorin-III are proteins that bind β-1,3-glucan. Finally, insects with nonpathogenic C. albicans exhibited induced immunity and were more resistant to candidiasis from the wild-type yeast cells than were noninduced insects.Key words: Candida, virulence, insect, nodule, melanization, apolipophorin-III.
Isolation and characterization of a zinc-containing metalloprotease expressed by Vibrio tubiashii
Authors: Delston R B , Kothary M H , Shangraw K A , Tall B D
Published: October 2003

A Vibrio tubiashii hemagglutinin, a protease, was purified by ammonium sulfate precipitation, gel filtration, and hydrophobic interaction chromatography. It agglutinates sheep, chicken, bovine, rabbit, guinea pig, and human erythrocytes. It has a molecular mass of 35 kDa, isoelectric points of 3.5 and 3.7, and is inhibited by ortho-phenanthro line, phosphoramidon, and Zincov. The N-terminal amino acid sequence (Ala-Gln-Ala-Thr-Gly-Thr-Gly- Pro-Gly-Gly-Asn-Gln-Lys-Thr-Gly-Gln- Tyr-Asn-Phe-Gly) has strong homology to other Vibrio proteases.Key words: Vibrio tubiashii, metalloprotease, hemagglutinin.
EndophyticnifHgene diversity in African sweet potato
Authors: Reiter Birgit , Bürgmann Helmut , Burg Kornel , Sessitsch Angela
Published: October 2003

A cultivation-independent approach was used to identify potentially nitrogen-fixing endophytes in seven sweet potato varieties collected in Uganda and Kenya. Nitrogenase reductase genes (nifH) were amplified by PCR, and amplicons were cloned in Escherichia coli. Clones were grouped by restriction fragment length polymorphism analysis, and representative nifH genes were sequenced. The resulting sequences had high homologies to nitrogenase reductases from α-, β-, and γ-Proteobacteria and low G+C Gram positives, however, about 50% of the sequences derived from rhizobia. Several highly similar or even identical nitrogenase reductase sequences clustering with different bacterial genera and species, including Sinorhizobium meliloti, Rhizobium sp. NGR234, Rhizobium etli, Klebsiella pneumoniae, and Paenibacillus odorifer, could be detected in different plants grown in distinct geographic locations. This suggests that these bacterial species preferentially colonize African sweet potato as endophytes and that the diazotrophic, endophytic microflora is determined only to a low degree by the plant genotype or the soil microflora.Key words: endophytes, nitrogenase reductase, nifH, nitrogen fixation, sweet potato.
The concentrations of hexadecane and inorganic nutrients modulate the production of extracellular membrane-bound vesicles, soluble protein, and bioemulsifier by Acinetobacter venetianus RAG-1 and Acinetobacter sp. strain HO1-N
Authors: Leahy Joseph G , Khalid Zafar M , Quintero Ernesto J , Jones-Meehan Joanne M , Heidelberg John F , Batchelor Patricia J , Colwell Rita R
Published: October 2003

In the present study, we addressed the possibility that the production of both bioemulsifiers and membrane-bound vesicles may be a common feature of the growth of Acinetobacter spp. on alkanes, and we determined the extent to which the release of extracellular products by these organisms is regulated by the concentrations of the alkane substrate and inorganic nutrients. To accomplish this objective, we grew Acinetobacter venetianus RAG-1 and Acinetobacter sp. strain HO1-N with different concentrations of nutrients and assayed for extracellular products. The results indicated that the release of vesicles, soluble protein, and bioemulsifier was promoted in various degrees by higher concentrations of hexadecane and inorganic nutrients, while the specific activities of the bioemulsifiers were enhanced with lower nutrient concentrations. Based on our findings, we propose that under conditions of nutrient excess, these strains produce membrane-bound vesicles to function in "luxury uptake" of the alkane substrate for delivery and storage in the form of inclusions. Under the same conditions, soluble bioemulsifier and protein may perform auxiliary roles in cell desorption and (or) alkane uptake. With low concentrations of nutrients, the decreased production of vesicles, protein, and bioemulsifier and the increased activity of the emulsifier may represent a mechanism for reducing biosynthetic demands and conserving cellular material.Key words: Acinetobacter, alkane, bioemulsifier, emulsan, vesicle.
Fitness cost of the green fluorescent protein in gastrointestinal bacteria
Authors: Rang Camilla , Galen James E , Kaper James B , Chao Lin
Published: October 2003

There are surprisingly few studies that have successfully used the green fluorescent protein (GFP) as a quantitative reporter in selection experiments screening for inducible bacterial promoters. One explanation is that GFP expression may confer a fitness cost for bacteria. To test this possibility, we monitored the doubling time in enteric bacteria expressing GFP. Four bacterial species, Escherichia coli, enterohaemorrhagic E. coli, Shigella flexneri, Salmonella typhi, and Vibrio cholerae, were examined. The level of GFP expression was varied by using a salt-inducible promoter. After accounting for the increase in doubling time resulting from elevated osmolarity, the doubling time of all bacteria was found to increase proportionally with GFP expression, and some strains were more affected than others. Cultures of the bacteria most affected by GFP exhibited a proportion of elongated cells, which suggests that GFP production could interfere with cell division in these strains. The results in this study show that GFP is costly to bacteria and suggest that overly active promoters should be difficult to obtain from a genomic promoter library. They also suggest that the chances of succeeding in using GFP as a reporter in selection experiments are increased by growing the bacteria for the fewest number of generations and by subduing the expression of GFP whenever possible, such as by using a low copy vector to clone the library.Key words: green fluorescent protein, protein cost, promoter activity.
Role of the Na+H+exchanger (NHE1) in heart muscle function during transient acidosis. A study in papillary muscles from rat and guinea pig hearts
Authors: Sundset Rune , Bertelsen Geir , Ytrehus Kirsti
Published: October 2003

The sodiumhydrogen exchanger (NHE) helps the cell to recover from intracellular acidosis. In this study, we have investigated the effect of HOE 642 (a specific NHE1 blocker) on papillary muscles from rats and guinea pigs during transient acidosis and PKC activation by recording developed force (DF), action potential characteristics, and electrical conductance (stimulusresponse interval). Two protocols were used, with or without HOE 642 (105mol/L): papillary muscle was exposed (i) for 15 min to a glucose-free, nonoxygenated HEPES buffer containing lactate (20 mmol/L) (pH 6.8) followed by 15 min recovery or (ii) to a PKC activator (phorbolmyristate acetate (PMA) (109mol/L)) for 30 min. The DF after acidification remained significantly decreased in the NHE-blocked papillary muscles. During recovery from acidosis, papillary muscles exposed to HOE 642 remained at a higher electrical resistance. The present study shows that post-acidotic continued depression of DF and change in tissue electrophysiological properties might occur as a result of blocking the NHE. During infarct development, the tissue-protecting effect of NHE blockade has been well documented. When acidosis or reduced contractile function is present, however, blocking NHE by HOE 642 might not improve the situation.Key words: sodiumhydrogen exchange (NHE), HOE 642 (cariporide), gap junction, PKC, acidosis.
Streptozotocin-induced increase in cholesterol ester transfer protein (CETP) and its reversal by insulin in transgenic mice expressing human CETP
Authors: Cheema Sukhinder Kaur , Rashid-Kolvear Fariborz
Published: October 2003

High plasma triacylglycerol and low high-density lipoprotein levels are risk factors for cardiovascular disease in diabetes. Plasma high-density lipoprotein levels are regulated by cholesterol ester transfer protein (CETP). The regulation of CETP under diabetic conditions is not clear, and this is due to a lack of appropriate models. We used transgenic mice expressing human CETP to study the regulation of this protein under type-1 diabetic conditions and further investigated whether insulin reverses the effect of diabetes. Mice expressing human CETP under the control of its natural flanking region and age-matched littermates not expressing this protein were made diabetic by injecting streptozotocin, and the reversal of diabetes was assessed by injecting insulin. The plasma total cholesterol, low-density lipoprotein-cholesterol, and triacylglycerol concentrations were elevated, whereas high-density lipoprotein-cholesterol concentrations were reduced after the onset of diabetes. Insulin injection partially recovered this effect. The plasma cholesterol ester transfer activity, CETP mass, and hepatic CETP mRNA abundance were significantly higher in diabetic mice that were partially restored by insulin administration. There was a strong correlation between high-density lipoprotein-cholesterol concentrations and cholesterol ester transfer activity. These results suggest that an increase in CETP under diabetic conditions might be a major factor responsible for increased incidence of diabetes-induced atherosclerosis.Key words: transgenic mice, streptozotocin-induced diabetes, cholesterol ester transfer protein.
Hormone replacement therapy improves distal radius bone structure by endocortical mineral deposition
Authors: Muller Monique E , Webber Colin E , Adachi Jonathan D
Published: October 2003

Hormone replacement therapy (HRT) produces a small increase in bone mineral density (BMD) when measured by dual energy X-ray absorptiometry (DXA). The corresponding decrease in fracture risk is more impressive, implying that other factors that contribute to bone strength are favourably modified by HRT. We investigated, using peripheral quantitated computed tomography (pQCT), the changes produced by HRT in both the distribution of mineral between cortical and trabecular bone and the changes produced by HRT in the apparent structure of trabecular bone, expressed as average hole area and apparent connectivity. Twenty-one postmenopausal women starting HRT and 32 control women were followed for 2 years, with distal radius pQCT measurements every 6 months. HRT prevented the loss of total bone mass seen in controls (p < 0.02). HRT also produced an apparent rapid loss of trabecular bone mass within the first 6 months of the study (p < 0.02), with an associated rapid loss in the apparent connectivity (p = 0.034). Average hole area also increased but not to a statistically significant extent. Exogenous estrogen apparently fills small marrow pores close to the endocortical surface, such that the pQCT-defined boundary between trabecular and cortical bone is shifted in favour of cortical bone. Trabecular bone structure indices are adversely affected, as the central, poorly interconnected trabecular bone with greater than average marrow spaces constitutes a greater fraction of the remaining trabecular bone. This study suggests that the improvements in fracture risk resulting from HRT are explained by a reversal of net endocortical resorption of bone.Key words: average hole area, connectivity, distal radius, endocortical resorption, hormone replacement therapy, peripheral quantitated computed tomography, trabecular structure.
Effect of ambient temperatures ranging from cold to heat on thermoregulation in conscious MK801-treated rats
Authors: Canini F , Bourdon L , Bittel J
Published: October 2003

The glutamate NMDA receptor has been suggested to be involved in thermoregulation. To further analyse its role, the thermoregulatory responses of rats treated with 0.5 mg·kg1 of dizocilpine (MK801) were compared with those of control rats treated only with the same volume of saline during a 180-min exposure at one of the six different ambient temperatures, ranging from cold to heat. Colonic temperature (Tco) and tail skin temperature (Ttail) were measured throughout using CuCt thermocouples. In the cold (2.4 and 12.3 °C), Tco decreased either sharply (MK801) or progressively (saline), reaching the same final value (2.4 °C) or a lower value in the MK801-treated rats (12.3 °C). At the same time, Ttail decreased in both groups. In the cool environment (20.7 °C), Tco and Ttail decreased in both groups, with lower final values in MK801-treated rats. At thermoneutrality (28.8 °C), the MK801-induced hyperthermia remained steady, while Ttail increased in both groups. In the heat (34.6 and 36.2 °C), Tco and Ttail increased in both groups, with higher final values in MK801-treated rats. Moreover, at 36.2 °C, only MK801-treated rats exhibited heatstroke. It is thus suggested that MK801-induced inhibition of NMDA receptors impairs thermoregulation, especially in the heat.Key words: thermoregulation, NMDA receptor, MK801, poikilothermia, rat.