349 research outputs found

    Genomic, Proteomic and Physiological Characterization of a T5-like Bacteriophage for Control of Shiga Toxin-Producing Escherichia coli O157:H7

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    Despite multiple control measures, Escherichia coli O157:H7 (STEC O157:H7) continues to be responsible for many food borne outbreaks in North America and elsewhere. Bacteriophage therapy may prove useful for controlling this pathogen in the host, their environment and food. Bacteriophage vB_EcoS_AKFV33 (AKFV33), a T5-like phage of Siphoviridae lysed common phage types of STEC O157:H7 and not non-O157 E. coli. Moreover, STEC O157:H7 isolated from the same feedlot pen from which the phage was obtained, were highly susceptible to AKFV33. Adsorption rate constant and burst size were estimated to be 9.31×10−9 ml/min and 350 PFU/infected cell, respectively. The genome of AKVF33 was 108,853 bp (38.95% G+C), containing 160 open reading frames (ORFs), 22 tRNA genes and 32 strong promoters recognized by host RNA polymerase. Of 12 ORFs without homologues to T5-like phages, 7 predicted novel proteins while others exhibited low identity (<60%) to proteins in the National Centre for Biotechnology Information database. AKVF33 also lacked the L-shaped tail fiber protein typical of T5, but was predicted to have tail fibers comprised of 2 novel proteins with low identity (37–41%) to tail fibers of E. coli phage phiEco32 of Podoviridae, a putative side tail fiber protein of a prophage from E. coli IAI39 and a conserved domain protein of E. coli MS196-1. The receptor-binding tail protein (pb5) shared an overall identify of 29–72% to that of other T5-like phages, with no region coding for more than 6 amino acids in common. Proteomic analysis identified 4 structural proteins corresponding to the capsid, major tail, tail fiber and pore-forming tail tip (pb2). The genome of AKFV33 lacked regions coding for known virulence factors, integration-related proteins or antibiotic resistance determinants. Phage AKFV33 is a unique, highly lytic STEC O157:H7-specific T5-like phage that may have considerable potential as a pre- and post-harvest biocontrol agent

    Predicting Transcriptional Activity of Multiple Site p53 Mutants Based on Hybrid Properties

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    As an important tumor suppressor protein, reactivate mutated p53 was found in many kinds of human cancers and that restoring active p53 would lead to tumor regression. In this work, we developed a new computational method to predict the transcriptional activity for one-, two-, three- and four-site p53 mutants, respectively. With the approach from the general form of pseudo amino acid composition, we used eight types of features to represent the mutation and then selected the optimal prediction features based on the maximum relevance, minimum redundancy, and incremental feature selection methods. The Mathew's correlation coefficients (MCC) obtained by using nearest neighbor algorithm and jackknife cross validation for one-, two-, three- and four-site p53 mutants were 0.678, 0.314, 0.705, and 0.907, respectively. It was revealed by the further optimal feature set analysis that the 2D (two-dimensional) structure features composed the largest part of the optimal feature set and maybe played the most important roles in all four types of p53 mutant active status prediction. It was also demonstrated by the optimal feature sets, especially those at the top level, that the 3D structure features, conservation, physicochemical and biochemical properties of amino acid near the mutation site, also played quite important roles for p53 mutant active status prediction. Our study has provided a new and promising approach for finding functionally important sites and the relevant features for in-depth study of p53 protein and its action mechanism

    Search for Kaluza-Klein Graviton Emission in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy Signature

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    We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb1{pb}^{-1} of \ppb collisions at s\sqrt{s} = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a 3+1+n3+1+n-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for nn=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure

    Measurement of the average time-integrated mixing probability of b-flavored hadrons produced at the Tevatron

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    We have measured the number of like-sign (LS) and opposite-sign (OS) lepton pairs arising from double semileptonic decays of bb and bˉ\bar{b}-hadrons, pair-produced at the Fermilab Tevatron collider. The data samples were collected with the Collider Detector at Fermilab (CDF) during the 1992-1995 collider run by triggering on the existence of μμ\mu \mu and eμe \mu candidates in an event. The observed ratio of LS to OS dileptons leads to a measurement of the average time-integrated mixing probability of all produced bb-flavored hadrons which decay weakly, χˉ=0.152±0.007\bar{\chi} = 0.152 \pm 0.007 (stat.) ±0.011\pm 0.011 (syst.), that is significantly larger than the world average χˉ=0.118±0.005\bar{\chi} = 0.118 \pm 0.005.Comment: 47 pages, 10 figures, 15 tables Submitted to Phys. Rev.

    Double Diffraction Dissociation at the Fermilab Tevatron Collider

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    We present results from a measurement of double diffraction dissociation in pˉp\bar pp collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width Δη0>3\Delta\eta^0>3 (overlapping η=0\eta=0) is found to be 4.43±0.02(stat)±1.18(syst)mb4.43\pm 0.02{(stat)}{\pm 1.18}{(syst) mb} [3.42±0.01(stat)±1.09(syst)mb3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}] at s=1800\sqrt{s}=1800 [630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.Comment: 10 pages, 4 figures, using RevTeX. Submitted to Physical Review Letter

    Search for Gluinos and Scalar Quarks in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy plus Multijets Signature

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    We have performed a search for gluinos (\gls) and squarks (\sq) in a data sample of 84 pb1^{-1} of \ppb collisions at s\sqrt{s} = 1.8 TeV, recorded by the Collider Detector at Fermilab, by investigating the final state of large missing transverse energy and 3 or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed `blind', in that the inspection of the signal region is made only after the predictions from Standard Model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 \gev (95% C.L.), independent of the squark mass. For the case \msq \approx \mgls, gluino masses below 300 \gev are excluded.Comment: 7 pages, 3 figure

    Diffractive Dijet Production at sqrt(s)=630 and 1800 GeV at the Fermilab Tevatron

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    We report a measurement of the diffractive structure function FjjDF_{jj}^D of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in pˉp\bar pp collisions at s=630\sqrt s=630 GeV at the Fermilab Tevatron. The ratio of FjjDF_{jj}^D at s=630\sqrt s=630 GeV to FjjDF_{jj}^D obtained from a similar measurement at s=1800\sqrt s=1800 GeV is compared with expectations from QCD factorization and with theoretical predictions. We also report a measurement of the ξ\xi (xx-Pomeron) and β\beta (xx of parton in Pomeron) dependence of FjjDF_{jj}^D at s=1800\sqrt s=1800 GeV. In the region 0.035<ξ<0.0950.035<\xi<0.095, t<1|t|<1 GeV2^2 and β<0.5\beta<0.5, FjjD(β,ξ)F_{jj}^D(\beta,\xi) is found to be of the form β1.0±0.1ξ0.9±0.1\beta^{-1.0\pm 0.1} \xi^{-0.9\pm 0.1}, which obeys β\beta-ξ\xi factorization.Comment: LaTeX, 9 pages, Submitted to Phys. Rev. Letter

    A Study of B0 -> J/psi K(*)0 pi+ pi- Decays with the Collider Detector at Fermilab

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    We report a study of the decays B0 -> J/psi K(*)0 pi+ pi-, which involve the creation of a u u-bar or d d-bar quark pair in addition to a b-bar -> c-bar(c s-bar) decay. The data sample consists of 110 1/pb of p p-bar collisions at sqrt{s} = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching ratios to be BR(B0 -> J/psi K*0 pi+ pi-) = (8.0 +- 2.2 +- 1.5) * 10^{-4} and BR(B0 -> J/psi K0 pi+ pi-) = (1.1 +- 0.4 +- 0.2) * 10^{-3}. Contributions to these decays are seen from psi(2S) K(*)0, J/psi K0 rho0, J/psi K*+ pi-, and J/psi K1(1270)

    Search for lepton flavor violating decays of a heavy neutral particle in p-pbar collisions at root(s)=1.8 TeV

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    We report on a search for a high mass, narrow width particle that decays directly to e+mu, e+tau, or mu+tau. We use approximately 110 pb^-1 of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions.Comment: Figure 2 fixed. Reference 4 fixed. Minor changes to tex
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