434 research outputs found
Identification and characterization of the TonB region and its role in transferrin-mediated iron acquisition in Haemophilus parasuis
12 p.Haemophilus parasuis is the causative agent of Glässer's disease, which is responsible for considerable economic losses in the pigrearing
industry. The aim of the study reported here was the identification, sequencing and molecular characterization of the TonB
region that includes tonB, exbBD, and tbpBA genes in H. parasuis. In addition, two fusion proteins were generated. One of them
(pGEX-6P-1-GST-TbpB) contained the first 501 amino acids of H. parasuis TbpB protein, while the second (pBAD-Thio-TbpBV5-
His) included the first 102 amino acids of H. parasuis TbpB N-terminus domain. A panel of 14 hybridomas secreting monoclonal
antibodies was raised against the two recombinant TbpB fusion proteins. Furthermore, to assess whether the expression of the
H. parasuis ExbB, TbpB, and TbpA proteins was upregulated under conditions of restricted availability of iron, a rabbit polyclonal
antibody against H. parasuis TbpB-His fusion protein was produced. A rabbit polyclonal antibody against serotype 7 of Actinobacillus
pleuropneumoniae ExbB and TbpA proteins was also used for the detection of the homologous proteins in H. parasuis. Overall,
the data indicate that H. parasuis, like other members of the Pasteurellaceae family, possesses the genetic elements of the TonB
region for iron acquisition and the transferrin-binding proteins encoded under this region are upregulated under restricted iron
availabilityS
Molecular characterization of Haemophilus parasuis ferric hydroxamate uptake (fhu) genes and constitutive expression of the FhuA receptor
P. 49-59Bacteria have evolved a set of highly specialized proteins to capture iron in irondepleted
environments. The acquisition and uptake of iron present in the extracellular milieu of
eukaryotic organisms is indispensable for the growth and survival of microbial pathogens in the
course of infection. Haemophilus parasuis is the causative agent of Glässer disease, which is
responsible for considerable financial losses in pig-rearing worldwide. To gain insight into the
mechanisms involved in siderophore-mediated iron uptake in H. parasuis, genes in the H. parasuis
ferric hydroxamate uptake (Fhu) region were amplified in the work being reported here. As has been
described in A. pleuropneumoniae, an Fhu genomic region was also present in H. parasuis, being
composed of four potential consecutive open reading frames (ORF) designated as fhuC, fhuD, fhuB,
and fhuA, respectively. By immunoblotting, using a cross-reactive polyclonal antibody raised
against Actinobacillus pleuropneumoniae FhuA protein, it was demonstrated that this protein was
constitutively expressed in H. parasuis and its level of expression was not modified under
conditions of restricted iron availability. This is the first report describing the presence of the fhu
genes in H. parasuis. Our results indicate that FhuA protein expression is not affected under ironrestricted
conditions, however, it is one of the targets of the humoral immune responseS
Remediación de aguas empleando catalizadores con vistas al desarrollo de un sistema integrado para la potabilización de aguas contaminadas con oxoaniones
Se estudió la eliminación de los oxoaniones NO3-, NO2- y BrO3- en muestras de agua sintética y real, empleando catalizadores en polvo y estructurados usando PdCu como fase activa soportados sobre materiales con características redox a base de CeO2 pura o modificada con 10%p/p ZrO2 (10ZrCe) y H2 como agente reductor. Se determinó por las técnicas de caracterización DRX, Raman, FTIR y TPR que los soportes CeO2 y 10ZrCe poseen vacancias de oxígeno siendo mayores en el soporte modificado con ZrO2 por la presencia de iones Zr4+ en la red de CeO2
Species-specific toxicity of copper nanoparticles among mammalian and piscine cell lines
Conservation Biolog
The exposure of the hybrid detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays.
It consists of a surface array to measure secondary particles at ground level
and a fluorescence detector to measure the development of air showers in the
atmosphere above the array. The "hybrid" detection mode combines the
information from the two subsystems. We describe the determination of the
hybrid exposure for events observed by the fluorescence telescopes in
coincidence with at least one water-Cherenkov detector of the surface array. A
detailed knowledge of the time dependence of the detection operations is
crucial for an accurate evaluation of the exposure. We discuss the relevance of
monitoring data collected during operations, such as the status of the
fluorescence detector, background light and atmospheric conditions, that are
used in both simulation and reconstruction.Comment: Paper accepted by Astroparticle Physic
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass . Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report
Numbe
Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP
Promptly decaying lightest neutralinos and long-lived staus are searched for
in the context of light gravitino scenarios. It is assumed that the stau is the
next to lightest supersymmetric particle (NLSP) and that the lightest
neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector
at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of
the production of these particles is found. Hence, lower mass limits for both
kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is
found to be greater than 71.5 GeV/c^2. In the search for long-lived stau,
masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10
to 150 \eVcc . Combining this search with the searches for stable heavy leptons
and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc
may be set for the stau mas
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
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