284 research outputs found

    Dynamics of Wolbachia pipientis gene expression across the Drosophila melanogaster life cycle

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    Symbiotic interactions between microbes and their multicellular hosts have manifold impacts on molecular, cellular and organismal biology. To identify candidate bacterial genes involved in maintaining endosymbiotic associations with insect hosts, we analyzed genome-wide patterns of gene expression in the alpha-proteobacteria Wolbachia pipientis across the life cycle of Drosophila melanogaster using public data from the modENCODE project that was generated in a Wolbachia-infected version of the ISO1 reference strain. We find that the majority of Wolbachia genes are expressed at detectable levels in D. melanogaster across the entire life cycle, but that only 7.8% of 1195 Wolbachia genes exhibit robust stage- or sex-specific expression differences when studied in the "holo-organism" context. Wolbachia genes that are differentially expressed during development are typically up-regulated after D. melanogaster embryogenesis, and include many bacterial membrane, secretion system and ankyrin-repeat containing proteins. Sex-biased genes are often organised as small operons of uncharacterised genes and are mainly up-regulated in adult males D. melanogaster in an age-dependent manner suggesting a potential role in cytoplasmic incompatibility. Our results indicate that large changes in Wolbachia gene expression across the Drosophila life-cycle are relatively rare when assayed across all host tissues, but that candidate genes to understand host-microbe interaction in facultative endosymbionts can be successfully identified using holo-organism expression profiling. Our work also shows that mining public gene expression data in D. melanogaster provides a rich set of resources to probe the functional basis of the Wolbachia-Drosophila symbiosis and annotate the transcriptional outputs of the Wolbachia genome.Comment: 58 pages, 6 figures, 6 supplemental figures, 4 supplemental files (available at https://github.com/bergmanlab/wolbachia/tree/master/gutzwiller_et_al/arxiv

    Effect of 17 Days of Bed Rest on Peak Isometric Force and Unloaded Shortening Velocity of Human Soleus Fibers

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    The purpose of this study was to examine the effect of prolonged bed rest (BR) on the peak isometric force (Po) and unloaded shortening velocity (Vo) of single Ca2+-activated muscle fibers. Soleus muscle biopsies were obtained from eight adult males before and after 17 days of 6° head-down BR. Chemically permeabilized single fiber segments were mounted between a force transducer and position motor, activated with saturating levels of Ca2+, and subjected to slack length steps. Vo was determined by plotting the time for force redevelopment vs. the slack step distance. Gel electrophoresis revealed that 96% of the pre- and 87% of the post-BR fibers studied expressed only the slow type I myosin heavy chain isoform. Fibers with diameter \u3e100 μm made up only 14% of this post-BR type I population compared with 33% of the pre-BR type I population. Consequently, the post-BR type I fibers (n = 147) were, on average, 5% smaller in diameter than the pre-BR type I fibers (n = 218) and produced 13% less absolute Po. BR had no overall effect on Po per fiber cross-sectional area (Po/CSA), even though half of the subjects displayed a decline of 9–12% in Po/CSA after BR. Type I fiber Vo increased by an average of 34% with BR. Although the ratio of myosin light chain 3 to myosin light chain 2 also rose with BR, there was no correlation between this ratio and Vo for either the pre- or post-BR fibers. In separate fibers obtained from the original biopsies, quantitative electron microscopy revealed a 20–24% decrease in thin filament density, with no change in thick filament density. These results raise the possibility that alterations in the geometric relationships between thin and thick filaments may be at least partially responsible for the elevated Vo of the post-BR type I fibers

    Measurement of the Λ(0)(b) lifetime in pp collisions at s√=7 TeV

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    This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2FJHEP07%282013%29163.A measurement of the Λ(0)(b) lifetime using the decay Λ(0)(b)→J/ψΛ in protonproton collisions at s√=7 TeV is presented. The data set, corresponding to an integrated luminosity of about 5 fb(−1), was recorded with the CMS experiment at the Large Hadron Collider using triggers that selected dimuon events in the J/ψ mass region. The Λ(0)(b) lifetime is measured to be 1.503 ± 0.052 (stat.) ± 0.031 (syst.) ps

    Fiber Reinforced Composite Cores and Panels

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    A fiber reinforced core panel is formed from strips of plastics foam helically wound with layers of rovings to form webs which may extend in a wave pattern or may intersect transverse webs. Hollow tubes may replace foam strips. Axial rovings cooperate with overlying helically wound rovings to form a beam or a column. Wound roving patterns may vary along strips for structural efficiency. Wound strips may alternate with spaced strips, and spacers between the strips enhance web buckling strength. Continuously wound rovings between spaced strips permit folding to form panels with reinforced edges. Continuously wound strips are helically wrapped to form annular structures, and composite panels may combine both thermoset and thermoplastic resins. Continuously wound strips or strip sections may be continuously fed either longitudinally or laterally into molding apparatus which may receive skin materials to form reinforced composite panels

    Search for new physics in events with same-sign dileptons and b jets in pp collisions at s√=8 TeV

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    This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2FJHEP03%282013%29037.A search for new physics is performed using events with isolated same-sign leptons and at least two bottom-quark jets in the final state. Results are based on a sample of proton-proton collisions collected at a center-of-mass energy of 8 TeV with the CMS detector and corresponding to an integrated luminosity of 10.5 fb(−1). No excess above the standard model background is observed. Upper limits are set on the number of events from non-standard-model sources and are used to constrain a number of new physics models. Information on acceptance and efficiencies is also provided so that the results can be used to confront an even broader class of new physics models

    Measurement of the production cross section for Zγ→ν(ν-bar)γ in pp collisions at s√=7 TeV and limits on ZZγ and Zγγ triple gauge boson couplings

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    This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2FJHEP10%282013%29164.A measurement of the Zγ→ν(ν-bar)γ cross section in pp collisions at s√=7 TeV is presented, using data corresponding to an integrated luminosity of 5.0 fb(−1) collected with the CMS detector. This measurement is based on the observation of events with an imbalance of transverse energy in excess of 130 GeV and a single photon in the absolute pseudorapidity range |η| < 1.4 with transverse energy above 145 GeV. The Zγ→ν(ν-bar)γ production cross section is measured to be 21.1 ± 4.2 (stat.) ± 4.3 (syst.) ± 0.5 (lum.) fb, which agrees with the standard model prediction of 21.9 ± 1.1 fb. The results are combined with the CMS measurement of Zγ production in the ℓ (+) ℓ (−) γ final state (where ℓ is an electron or a muon) to yield the most stringent limits to date on triple gauge boson couplings: ∣∣h(Z)(3)∣∣<2.7×10(−3) , ∣∣h(Z)(4)∣∣<1.3×10(−5) for ZZγ and ∣∣h(γ)(3)∣∣<2.9×10(−3) , ∣∣h(γ)(4)∣∣<1.5×10(−5) for Zγγ couplings

    Measurement of the W-boson helicity in top-quark decays from tt-bar production in lepton+jets events in pp collisions at s√=7 TeV

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    This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2FJHEP10%282013%29167.The W-boson helicity fractions in top-quark decays are measured with tt-bar events in the lepton+jets final state, using proton-proton collisions at a centre-of-mass energy of 7 TeV, collected in 2011 with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5.0 fb(−1). The measured fractions of longitudinal, left-, and right-handed helicity are F 0 = 0.682 ± 0.030 (stat.) ± 0.033 (syst.), F L = 0.310 ± 0.022 (stat.) ± 0.022 (syst.), and F R = 0.008 ± 0.012 (stat.) ± 0.014 (syst.), consistent with the standard model predictions. The measured fractions are used to probe the existence of anomalous Wtb couplings. Exclusion limits on the real components of the anomalous couplings g L , g R are also derived

    Search for supersymmetry in final states with a single lepton, b-quark jets, and missing transverse energy in proton-proton collisions at s√=7  TeV

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    This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.87.052006.A search motivated by supersymmetric models with light top squarks is presented using proton-proton collision data recorded with the CMS detector at a center-of-mass energy of s√=7  TeV during 2011, corresponding to an integrated luminosity of 4.98  fb(−1). The analysis is based on final states with a single lepton, b-quark jets, and missing transverse energy. Standard model yields are predicted from data using two different approaches. The observed event numbers are found to be compatible with these predictions. Results are interpreted in the context of the constrained minimal supersymmetric standard model and of a simplified model with four top quarks in the final state

    Search for pair-produced dijet resonances in four-jet final states in pp collisions at s√=7  TeV

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    This is the publisher's version, also available electronically from http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.110.141802.A search for the pair production of a heavy, narrow resonance decaying into two jets has been performed using events collected in s√=7  TeV pp collisions with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5.0  fb(−1). Events are selected with at least four jets and two dijet combinations with similar dijet mass. No resonances are found in the dijet mass spectrum. The upper limit at 95% confidence level on the product of the resonance pair production cross section, the branching fractions into dijets, and the acceptance varies from 0.22 to 0.005 pb, for resonance masses between 250 and 1200 GeV. Pair-produced colorons decaying into qq-bar are excluded for coloron masses between 250 and 740 GeV
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