DNA microarray analysis of Salmonella serotype Typhimurium strains causing different symptoms of disease

<p>Abstract</p> <p>Background</p> <p><it>Salmonella enterica </it>subsp. <it>enterica </it>is one of the leading food-borne pathogens in the USA and European countries. Outcome of human <it>Salmonella </it>serotype Typhimurium infections ranges from mild self-limiting diarrhoea to severe diarrhoea that requires hospitalization. Increased knowledge of the mechanisms that are responsible for causing infection and especially the severity of infection is of high interest.</p> <p>Results</p> <p>Strains were selected from patients with mild infections (n = 9) and patients with severe infections (n = 9) and clinical data allowed us to correct for known underlying diseases. Additionally, outbreak isolates (n = 3) were selected. Strains were analyzed on a DNA-DNA microarray for presence or absence of 281 genes covering marker groups of genes related to pathogenicity, phages, antimicrobial resistance, fimbriae, mobility, serotype and metabolism. Strains showed highly similar profiles when comparing virulence associated genes, but differences between strains were detected in the prophage marker group. The <it>Salmonella </it>virulence plasmid was present in 72% of the strains, but presence or absence of the virulence plasmid did not correspond to disease symptoms. A dendrogram clustered strains into four groups. Clustering confirmed DT104 as being a clonal phagetype. Clustering of the remaining strains was mainly correlated to presence or absence of the virulence plasmid and mobile elements such as transposons. Each of the four clusters in the tree represented an almost equal amount of strains causing severe or mild symptoms of infection.</p> <p>Conclusions</p> <p>We investigated clinical significance of known virulence factors of <it>Salmonella </it>serotype Typhimurium strains causing different disease symptoms, and conclude that the few detected differences in <it>Salmonella </it>serotype Typhimurium do not affect outcome of human disease.</p

The guanine-nucleotide exchange factor CalDAG GEFI fine-tunes functional properties of regulatory T cells

Using quantitative phosphopeptide sequencing of unstimulated versus stimulated primary murine Foxp3(+) regulatory and Foxp3(-) conventional T cells (Tregs and Tconv, respectively), we detected a novel and differentially regulated tyrosine phosphorylation site within the C1 domain of the guanine-nucleotide exchange factor CalDAG GEFI. We hypothesized that the Treg-specific and activation-dependent reduced phosphorylation at Y523 allows binding of CalDAG GEFI to diacylglycerol, thereby impacting the formation of a Treg-specific immunological synapse. However, diacylglycerol binding assays of phosphomutant C1 domains of CalDAG GEFI could not confirm this hypothesis. Moreover, CalDAG GEFI(-/-) mice displayed normal Treg numbers in thymus and secondary lymphoid organs, and CalDAG GEFI(-/-) Tregs showed unaltered in vitro suppressive capacity when compared to CalDAG GEFI(+/+) Tregs. Interestingly, when tested in vivo, CalDAG GEFI(-/-) Tregs displayed a slightly reduced suppressive ability in the transfer colitis model when compared to CalDAG GEFI(+/+) Tregs. Additionally, CRISPR-Cas9-generated CalDAG GEFI(-/-) Jurkat T cell clones showed reduced adhesion to ICAM-1 and fibronectin when compared to CalDAG GEFI-competent Jurkat T cells. Therefore, we speculate that deficiency in CalDAG GEFI impairs adherence of Tregs to antigen-presenting cells, thereby impeding formation of a fully functional immunological synapse, which finally results in a reduced suppressive potential

Design and Performance of SiPM-Based Readout of PbF\u3csub\u3e2\u3c/sub\u3e Crystals for High-Rate, Precision Timing Applications

We have developed a custom amplifier board coupled to a large-format 16-channel Hamamatsu silicon photomultiplier device for use as the light sensor for the electromagnetic calorimeters in the Muon g - 2 experiment at Fermilab. The calorimeter absorber is an array of lead-fluoride crystals, which produces short-duration Cherenkov light. The detector sits in the high magnetic field of the muon storage ring. The SiPMs selected, and their accompanying custom electronics, must preserve the short pulse shape, have high quantum efficiency, be non-magnetic, exhibit gain stability under varying rate conditions, and cover a fairly large fraction of the crystal exit surface area. We describe an optimized design that employs the new-generation of thru-silicon via devices. The performance is documented in a series of bench and beam tests

Methylation matters: binding of Ets-1 to the demethylated Foxp3 gene contributes to the stabilization of Foxp3 expression in regulatory T cells

The forkhead-box protein P3 (Foxp3) is a key transcription factor for the development and suppressive activity of regulatory T cells (Tregs), a T cell subset critically involved in the maintenance of self-tolerance and prevention of over-shooting immune responses. However, the transcriptional regulation of Foxp3 expression remains incompletely understood. We have previously shown that epigenetic modifications in the CpG-rich Treg-specific demethylated region (TSDR) in the Foxp3 locus are associated with stable Foxp3 expression. We now demonstrate that the methylation state of the CpG motifs within the TSDR controls its transcriptional activity rather than a Treg-specific transcription factor network. By systematically mutating every CpG motif within the TSDR, we could identify four CpG motifs, which are critically determining the transcriptional activity of the TSDR and which serve as binding sites for essential transcription factors, such as CREB/ATF and NF-κB, which have previously been shown to bind to this element. The transcription factor Ets-1 was here identified as an additional molecular player that specifically binds to the TSDR in a demethylation-dependent manner in vitro. Disruption of the Ets-1 binding sites within the TSDR drastically reduced its transcriptional enhancer activity. In addition, we found Ets-1 bound to the demethylated TSDR in ex vivo isolated Tregs, but not to the methylated TSDR in conventional CD4+ T cells. We therefore propose that Ets-1 is part of a larger protein complex, which binds to the TSDR only in its demethylated state, thereby restricting stable Foxp3 expression to the Treg lineage

Search for Top Squark Pair Production in the Dielectron Channel

This report describes the first search for top squark pair production in the channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using 74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence level upper limit on sigma*B is presented. The limit is above the theoretical expectation for sigma*B for this process, but does show the sensitivity of the current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report

Search for a Fourth Generation Charge -1/3 Quark via Flavor Changing Neutral Current Decay

We report on a search for pair production of a fourth generation charge -1/3 quark (b') in pbar p collisions at sqrt(s) = 1.8 TeV at the Fermilab Tevatron using an integrated luminosity of 93 pb^-1. Both quarks are assumed to decay via flavor changing neutral currents (FCNC). The search uses the signatures gamma + 3 jets + mu-tag and 2 gamma + 2 jets. We see no significant excess of events over the expected background. We place an upper limit on the production cross section times branching fraction that is well below theoretical expectations for a b' quark decaying exclusively via FCNC for b' quark masses up to m(Z) + m(b).Comment: Eleven pages, two postscript figures, submitted to Physical Review Letter

Measurement of the Top Quark Mass Using Dilepton Events

The D0 collaboration has performed a measurement of the top quark mass based on six candidate events for the process t tbar -> b W+ bbar W-, where the W bosons decay to e nu or mu nu. This sample was collected during an exposure of the D0 detector to an integrated luminosity of 125 pb^-1 of sqrt(s)=1.8 TeV p-pbar collisions. We obtain mt = 168.4 +- 12.3 (stat) +- 3.7 (sys) GeV/c^2, consistent with the measurement obtained using single-lepton events. Combination of the single-lepton and dilepton results yields mt = 172.0 +- 7.5 GeV/c^2.Comment: 12 pages, 3 figure

Measurement of the WW Boson Mass

A measurement of the mass of the $W$ boson is presented based on a sample of 5982 $W \rightarrow e \nu$ decays observed in $p\overline{p}$ collisions at $\sqrt{s}$ = 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a fit to the transverse mass spectrum, combined with measurements of the $Z$ boson mass, the $W$ boson mass is measured to be $M_W = 80.350 \pm 0.140 (stat.) \pm 0.165 (syst.) \pm 0.160 (scale) GeV/c^2$.Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures (submitted to PRL