324,534 research outputs found
A eukaryotic-like 3′ untranslated region in Salmonella enterica hilD mRNA
No full textLong 3' untranslated regions (3'UTRs) are common in eukaryotic mRNAs. In contrast, long 3'UTRs are rare in bacteria, and have not been characterized in detail. We describe a 3'UTR of 310 nucleotides in hilD mRNA, a transcript that encodes a transcriptional activator of Salmonella enterica pathogenicity island 1 (SPI-1). Deletion of the hilD 3'UTR increases the hilD mRNA level, suggesting that the hilD 3'UTR may play a role in hilD mRNA turnover. Cloning of the hilD 3'UTR downstream of the green fluorescent protein (gfp) gene decreases green fluorescent protein (GFP) activity in both Escherichia coli and S. enterica, indicating that the hilD 3'UTR can act as an independent module. S. enterica mutants lacking either ribonuclease E or polynucleotide phosphorylase contain similar amounts of hilD and hilD Δ3'UTR mRNAs, suggesting that the hilD 3'UTR is a target for hilD mRNA degradation by the degradosome. The hilD 3'UTR is also necessary for modulation of hilD and SPI-1 expression by the RNA chaperone Hfq. Overexpression of SPI-1 in the absence of the hilD 3'UTR retards Salmonella growth and causes uncontrolled invasion of epithelial cells. Based on these observations, we propose that the S. enterica hilD 3'UTR is a cis-acting element that contributes to cellular homeostasis by promoting hilD mRNA turnover.Ministerio de Economía y Competitividad BIO2010- 15023 y CSD2008-00013Junta de Andalucía P10-CVI-587
A eukaryotic-like 3′ untranslated region in Salmonella enterica hilD mRNA
No full textLong 3′ untranslated regions (3′UTRs) are common in eukaryotic mRNAs. In contrast, long 3′UTRs are rare in bacteria, and have not been characterized in detail. We describe a 3′UTR of 310 nucleotides in hilD mRNA, a transcript that encodes a transcriptional activator of Salmonella enterica pathogenicity island 1 (SPI-1). Deletion of the hilD 3′UTR increases the hilD mRNA level, suggesting that the hilD 3′UTR may play a role in hilD mRNA turnover. Cloning of the hilD 3′UTR downstream of the green fluorescent protein (gfp) gene decreases green fluorescent protein (GFP) activity in both Escherichia coli and S. enterica, indicating that the hilD 3′UTR can act as an independent module. S. enterica mutants lacking either ribonuclease E or polynucleotide phosphorylase contain similar amounts of hilD and hilD Δ3′UTR mRNAs, suggesting that the hilD 3′UTR is a target for hilD mRNA degradation by the degradosome. The hilD 3′UTR is also necessary for modulation of hilD and SPI-1 expression by the RNA chaperone Hfq. Overexpression of SPI-1 in the absence of the hilD 3′UTR retards Salmonella growth and causes uncontrolled invasion of epithelial cells. Based on these observations, we propose that the S. enterica hilD 3′UTR is a cis-acting element that contributes to cellular homeostasis by promoting hilD mRNA turnover
Signals, benefits, and costs of the HilD-regulon expression.
No full text(A) The HilD regulon (center) has a complex architecture (for details, see [34,35]) and computes responses to a variety of environmental signals. Many of these signals are derived or controlled by the microbiota and the host. They provide environmental cues for controlled expression of S. Typhimurium virulence factors and physiological adaptations ensuring growth and survival such that the associated costs occur only at those moments of the infection cycle when the respective virulence factors are needed. The HilD regulon limits their costly expression to the gut lumen and shuts them off after mucosa invasion [36]. Moreover, the HilD regulon limits these costs of virulence expression to a subpopulation of the gut-luminal S. Typhimurium cells by ensuring that only a subset of the pathogen population is expressing hilD (bistable expression) [28,29]. Thus, in hosts with severely disrupted microbiota, the main function of the HilD regulon seems to reside in minimizing the costs associated with the triggering of gut inflammation by TTSS-1-, flagella-, and/or Sii-adhesin-dependent mucosa invasion. This host response promotes pathogen blooms in the gut lumen and thereby enhances transmission. The exact molecular nature of these costs is still being explored. In antibiotic pretreated mice, these costs entail reduced growth rates as observed ex vivo [37], death from innate host defenses encountered after tissue invasion [28,93], an altered sensitivity towards SCFA-mediated growth restriction [62,94], or a reduced energy level and an increased sensitivity of the regulon-expressing cells towards outer membrane disruption [95]. The sheer number of genes and phenotypes controlled by the HilD regulon [96] has been an obstacle in deciphering the cause of its expression costs. Our work presented here suggests that the gut microbiota are playing a critical role, by conditioning the gut milieu and thereby affect the relative costs and benefits of the HilD-regulon outputs. This explains why mice with intermediate CR tend to select for S. Typhimurium clones retaining an intact HilD-regulon. (B) HilD-regulon expression phenotypes of the key Salmonella strains used in this study. It should be noted that colonies derived from strains featuring an intact HilD regulon will express low levels of virulence factors when growing as colonies on plates. Therefore, these colonies will yield a positive western blot signal in the colony protein blot assay, as they secrete the TTSS-1 translocon and effector protein SipC [29,50]. (TIF)</p
Competitive infection of <i>S</i>.Tm* and <i>S</i>.Tm*<sup><i>hilD</i></sup> in LCM mice.
No full text(A) Experimental scheme. (B–E) LCM mice were infected with a 100:1 mixture of S.Tm* and the isogenic hilD mutant S.Tm* hilD (5 × 107 CFU, by gavage; n = 7 mice) for 40 days. (B) Total fecal Salmonella loads, as determined using MacConkey plates with selective antibiotics. (C) Fecal S.Tm* and S.Tm* hilD loads, as determined using MacConkey plates with selective antibiotics. (D) Competitive index (C.I.) of S.Tm* hilD vs. S.Tm*, as determined using MacConkey plates with selective antibiotics. The C.I. is normalized to the inoculum. The dotted line indicates a C.I. of 1. (E) Lipocalin-2 ELISA as performed on the feces. We analyzed a minimum n = 3 fecal pellets per time point. Dotted lines indicate the detection limit. Lines connect the median values at the days of analysis. Source data can be found in S1 Data file. Interpretation: In the LCM mice, we observed a selection for the hilD-deficient strain during the first 10 days of the infection. This is likely attributable to the inflamed gut-luminal milieu, which selected for the hilD mutant. Also, the inflammation has likely disturbed the LCM microbiota such that it cannot establish conditions selecting against the hilD mutant during these 10 days. The gut inflammation was apparently resolved by days 20–40, as indicated by the lipocalin-e ELISA data. In this period of the experiment, the selective advantage of the hilD-deficient strain was reversed. We hypothesize that this is attributable to the re-establishment of the LCM microbiota and that this accounts for the 10,000-fold selection of the hilD-proficient over the hilD-deficient strain (C.I. = 102 at day 10; versus C.I. = 10−2 at day 30). (TIF)</p
Assessment of Uncertainties in Treatment Planning for Scanned Ion Beam Therapy of Moving Tumors
No full textPURPOSE: To provide methods for quantification of uncertainties in 4-dimensional (4D) treatment during treatment planning. METHODS AND MATERIALS: Uncertainty information was generated by multiple 4D treatment simulations with varying parameters. Sampled data were analyzed using uncertainty visualization methods that have been added to common treatment plan evaluation methods (eg, dose-volume histogram and dose distribution analysis). To illustrate the potential of the introduced methods, uncertainty analysis was completed for a single lung cancer case using 3 motion mitigation techniques: gating, slice-by-slice rescanning, and breath-controlled rescanning. RESULTS: By repeating 4D dose calculations with varying parameters, we were able to show local uncertainties in dose distributions and to evaluate the stability of treatment setups. The new methods were found suitable for uncertainty evaluation in 4D treatment planning of moving tumors. Calculation time of the uncertainty base data was time consuming but contrivable overnight. CONCLUSIONS: Uncertainty analysis and visualization for 4D treatment planning provide an important tool in the decision process for an optimal treatment approach
Das Wärmedämmverbundsystem unter bauphysikalischen Aspekten
No full textS.24-37Aufzeichnung des Gesprächs von Andreas Hild mit Gerd Hauser und Andreas Holm
Identification of adhesive properties in GLARE laminates by Digital Image Correlation
No full textOne page abstrac
Assessment of interface properties and boundary conditionsby Digital Image Correlation and Kalman filter
No full textAbstract 2 pag
Una metodologia basata sulla Correlazione di Immaginiper l’identificazione del comportamento a fratturadi giunti ed interfacce
No full textIn questa comunicazione si propone una metodologia inversa per la caratterizzazione meccanica di
giunti/interfacce alla microscala, basata su misure senza contatto, a tutto campo, mediante correlazione di
immagini digitali. Seguendo un approccio locale, le misure cinematiche raccolte durante una prova di frattura
non-convenzionale vengono impiegate, da una parte, per guidare le simulazioni ad elementi finiti che riguardano
esclusivamente il sotto-dominio monitorato, quali condizioni di Dirichlet imposte sul bordo, e dall’altra parte
come termini di confronto a fini identificativi, da includere nella funzione obiettivo
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