Pathogenitätsrelevante Signalkaskaden in Ustilago maydis: Identifikation von Zielgenen

In Ustilago maydis sind drei Signalwege bekannt, die für die pathogene Entwicklung dieses Brandpilzes essentiell sind. Während die Kpp4/Fuz7/Kpp2-MAPK-Kaskade und der cAMP-Weg für den Paarungsprozess und die Ausbildung von frühen Infektionsstrukturen benötigt werden, ist die Kpp6-MAPK-Kaskade entscheidend für die Penetration der Blattoberfläche. Bisher waren nur wenige Zielgene dieser Signalwege bekannt. In dieser Arbeit wurden isogene Stämme konstruiert, die eine regulierbare genetische Aktivierung der einzelnen Signalkaskaden ermöglichen. Durch genomweite Microarray-Analysen (Affymetrix)wurde das Transkriptom dieser Stämme untersucht und mit der Situation nach Pheromonstimulation verglichen. Unter den differentiell regulierten Genen konnten neben zahlreichen bekannten auch eine Vielzahl neuer Zielgene identifiziert werden. Vergleichende Analysen der Transkriptome zeigen, dass eine deutliche Überlappung der Signalwege vorliegt. An der Regulation dieses Netzwerks sind neben dem HMG-Domänen Transkriptionsfaktor Prf1 weitere Komponenten beteiligt, die vermutlich posttranskriptionell reguliert werden. Nach Aktivierung des cAMP-Wegs wurden drei koregulierte Gencluster identifiziert, die eine potentielle Funktion bei der Eisenaufnahme haben. Unter den koregulierten Genen befinden sich Vertreter des reduktiven und des nicht-reduktiven Eisenaufnahme-systems, u.a. die bereits bekannten Gene sid1 und sid2, die für eine Ornithin-5-Monooxigenase und eine Ferrichrom-Siderophoren-Peptidsynthetase kodieren. Für die Expression dieser Gene wird ein intakter cAMP-Weg benötigt, darüber hinaus werden die Gene durch Eisen reprimiert. Da bereits bekannt war, dass das nicht-reduktive Eisenaufnahmesystem keine Rolle bei der pathogenen Entwicklung von U. maydis spielt, konzentrierte sich die Arbeit auf die hochaffine Eisenpermease die Teil des reduktiven Eisenaufnahmesystems ist. Durch Komplementation einer Hefemutante konnte gezeigt werden, dass fer2 für eine funktionelle Eisenpermease kodiert. fer2-Deletionsmutanten zeigen einen Wachstumsdefekt auf Eisenmangelmedium. In der Pflanze ist die Proliferation solcher Mutanten stark reduziert und die Ausbildung von Pathogenitätssymptomen deutlich abgeschwächt. Dies zeigt, dass Komponenten des reduktiven Eisenaufnahmesystems Virulenzfaktoren in U. maydis sind

Pathogenitätsrelevante Signalkaskaden in Ustilago maydis: Identifikation von Zielgenen

In Ustilago maydis sind drei Signalwege bekannt, die für die pathogene Entwicklung dieses Brandpilzes essentiell sind. Während die Kpp4/Fuz7/Kpp2-MAPK-Kaskade und der cAMP-Weg für den Paarungsprozess und die Ausbildung von frühen Infektionsstrukturen benötigt werden, ist die Kpp6-MAPK-Kaskade entscheidend für die Penetration der Blattoberfläche. Bisher waren nur wenige Zielgene dieser Signalwege bekannt. In dieser Arbeit wurden isogene Stämme konstruiert, die eine regulierbare genetische Aktivierung der einzelnen Signalkaskaden ermöglichen. Durch genomweite Microarray-Analysen (Affymetrix)wurde das Transkriptom dieser Stämme untersucht und mit der Situation nach Pheromonstimulation verglichen. Unter den differentiell regulierten Genen konnten neben zahlreichen bekannten auch eine Vielzahl neuer Zielgene identifiziert werden. Vergleichende Analysen der Transkriptome zeigen, dass eine deutliche Überlappung der Signalwege vorliegt. An der Regulation dieses Netzwerks sind neben dem HMG-Domänen Transkriptionsfaktor Prf1 weitere Komponenten beteiligt, die vermutlich posttranskriptionell reguliert werden. Nach Aktivierung des cAMP-Wegs wurden drei koregulierte Gencluster identifiziert, die eine potentielle Funktion bei der Eisenaufnahme haben. Unter den koregulierten Genen befinden sich Vertreter des reduktiven und des nicht-reduktiven Eisenaufnahme-systems, u.a. die bereits bekannten Gene sid1 und sid2, die für eine Ornithin-5-Monooxigenase und eine Ferrichrom-Siderophoren-Peptidsynthetase kodieren. Für die Expression dieser Gene wird ein intakter cAMP-Weg benötigt, darüber hinaus werden die Gene durch Eisen reprimiert. Da bereits bekannt war, dass das nicht-reduktive Eisenaufnahmesystem keine Rolle bei der pathogenen Entwicklung von U. maydis spielt, konzentrierte sich die Arbeit auf die hochaffine Eisenpermease die Teil des reduktiven Eisenaufnahmesystems ist. Durch Komplementation einer Hefemutante konnte gezeigt werden, dass fer2 für eine funktionelle Eisenpermease kodiert. fer2-Deletionsmutanten zeigen einen Wachstumsdefekt auf Eisenmangelmedium. In der Pflanze ist die Proliferation solcher Mutanten stark reduziert und die Ausbildung von Pathogenitätssymptomen deutlich abgeschwächt. Dies zeigt, dass Komponenten des reduktiven Eisenaufnahmesystems Virulenzfaktoren in U. maydis sind

Automatic optimization of load angles for a linear hybrid stepper motor

The objective of this contribution is a linear direct drive based on the working principle of hybrid stepper technology. Herein, reluctant forces enable the thrust of this type of drive. In order to improve the dynamic performance a method adjusting the optimal load angle with respect to the driven velocity is presented. Commonly, the phases of the linear hybrid stepper motor (LHSM) are commutated sinusoidal with a constant load angle of 90 degrees. Due to delay times of sensors, actuators and hardware, the coils of the phases are not energized optimally in terms of maximum force application. Thus, variable load angles subject to velocity are introduced. This contribution comprises the optimization of the load angles. To solve this one-dimensional optimization task, bracketing methods can be used. These algorithms work without derivatives and find the minimum through iterative decreasing of the interval until a desired tolerance is achieved. Regarding the implementation, signal processing has to be done beside the optimization algorithm to ensure feasible solutions. The entire optimization process can be carried out automatically on the test rig. As a result, a characteristic curve is obtained describing the optimal load angle to velocity relation. Including the directionality, the characteristic curves are distinguished between forward and backward drive. Further properties of the optimization algorithm such as convergence and reproducibility are examined and discussed. The curves are implemented on a real-time system facilitating a comparison with constant load angle commutation. Velocity control measurements exhibit an improved performance, especially at high motion dynamics

QPCR: Application for real-time PCR data management and analysis

BACKGROUND: Since its introduction quantitative real-time polymerase chain reaction (qPCR) has become the standard method for quantification of gene expression. Its high sensitivity, large dynamic range, and accuracy led to the development of numerous applications with an increasing number of samples to be analyzed. Data analysis consists of a number of steps, which have to be carried out in several different applications. Currently, no single tool is available which incorporates storage, management, and multiple methods covering the complete analysis pipeline. RESULTS: QPCR is a versatile web-based Java application that allows to store, manage, and analyze data from relative quantification qPCR experiments. It comprises a parser to import generated data from qPCR instruments and includes a variety of analysis methods to calculate cycle-threshold and amplification efficiency values. The analysis pipeline includes technical and biological replicate handling, incorporation of sample or gene specific efficiency, normalization using single or multiple reference genes, inter-run calibration, and fold change calculation. Moreover, the application supports assessment of error propagation throughout all analysis steps and allows conducting statistical tests on biological replicates. Results can be visualized in customizable charts and exported for further investigation. CONCLUSION: We have developed a web-based system designed to enhance and facilitate the analysis of qPCR experiments. It covers the complete analysis workflow combining parsing, analysis, and generation of charts into one single application. The system is freely available a

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

Peer reviewe

Search for anomalous production of events with three or more leptons in pp collisions at √s = 8TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.A search for physics beyond the standard model in events with at least three leptons is presented. The data sample, corresponding to an integrated luminosity of 19.5fb-1 of proton-proton collisions with center-of-mass energy s=8TeV, was collected by the CMS experiment at the LHC during 2012. The data are divided into exclusive categories based on the number of leptons and their flavor, the presence or absence of an opposite-sign, same-flavor lepton pair (OSSF), the invariant mass of the OSSF pair, the presence or absence of a tagged bottom-quark jet, the number of identified hadronically decaying τ leptons, and the magnitude of the missing transverse energy and of the scalar sum of jet transverse momenta. The numbers of observed events are found to be consistent with the expected numbers from standard model processes, and limits are placed on new-physics scenarios that yield multilepton final states. In particular, scenarios that predict Higgs boson production in the context of supersymmetric decay chains are examined. We also place a 95% confidence level upper limit of 1.3% on the branching fraction for the decay of a top quark to a charm quark and a Higgs boson (t→cH), which translates to a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, λtcH and λctH, respectively, of |λtcH|2+|λctH|2<0.21