Bacillus subtilis Tolerance of Moderate Concentrations of Rifampin Involves the ς(B)-Dependent General and Multiple Stress Response

Low concentrations of the RNA polymerase inhibitor rifampin added to an exponentially growing culture of Bacillus subtilis led to an instant inhibition of growth. Survival experiments revealed that during the growth arrest the cells became tolerant to the antibiotic and the culture was able to resume growth some time after rifampin treatment. l-[(35)S]methionine pulse-labeled protein extracts were separated by two-dimensional polyacrylamide gel electrophoresis to investigate the change in the protein synthesis pattern in response to rifampin. The ς(B)-dependent general stress proteins were found to be induced after treatment with the antibiotic. Part of the oxidative stress signature was induced as indicated by the catalase KatA and MrgA. The target protein of rifampin, the β subunit (RpoB) of the DNA-dependent RNA polymerase, and the flagellin protein Hag belonging to the ς(D) regulon were also induced. The rifampin-triggered growth arrest was extended in a sigB mutant in comparison to the wild-type strain, and the higher the concentration, the more pronounced this effect was. Activity of the RsbP energy-signaling phosphatase in the ς(B) signal transduction network was also important for this protection against rifampin, but the RsbU environmental signaling phosphatase was not required. The sigB mutant strain was less capable of growing on rifampin-containing agar plates. When plated from a culture that had already reached stationary phase without previous exposure to the antibiotic during growth, the survival rate of the wild type exceeded that of the sigB mutant by a factor of 100. We conclude that the general stress response of B. subtilis is induced by rifampin depending on RsbP activity and that loss of SigB function causes increased sensitivity to the antibiotic

Arbeitsplatz Universität : [die Ausstellung findet vom 16.04.2002 bis 16.06.2002 in der Universitätsbibliothek statt] ; ein Projekt der Philipps-Universität Marburg ...

Layoutgetreues Digitalisat der Ausg.: Marburg : Univ.-Bibl., 2002 Standort: Universität Marburg, Zentralbibliothek (4) Signatur: 4 A 73/505, 112 Bemerkungen: Schriften der Universitätsbibliothek Marburg ; 11

Proteomic Approach to Understanding Antibiotic Action

We have used proteomic technology to elucidate the complex cellular responses of Bacillus subtilis to antimicrobial compounds belonging to classical and emerging antibiotic classes. We established on two-dimensional gels a comprehensive database of cytoplasmic proteins with pIs covering a range of 4 to 7 that were synthesized during treatment with antibiotics or agents known to cause generalized cell damage. Although each antibiotic showed an individual protein expression profile, overlaps in the expression of marker proteins reflected similarities in molecular drug mechanisms, suggesting that novel compounds with unknown mechanisms of action may be classified. Indeed, one such substance, a structurally novel protein synthesis inhibitor (BAY 50-2369), could be classified as a peptidyltransferase inhibitor. These results suggest that this technique gives new insights into the bacterial response toward classical antibiotics and hints at modes of action of novel compounds. Such a method should prove useful in the process of antibiotic drug discovery

Influence of fiber diameter and surface roughness of electrospun vascular grafts on blood activation

Electrospun grafts are widely investigated for vascular graft replacement due to their ease and compatibility with many natural and synthetic polymers. Here, the effect of the processing parameters on the scaffold's architecture and subsequent reactions of partially heparinized blood triggered by contacting these topographies were studied. Degrapol(®) (DP) and poly(lactic-co-glycolic acid (PLGA) electrospun fibrous scaffolds were characterized with regard to fiber diameter, pore area and scaffold roughness. The study showed that electrospinning parameters greatly affect fiber diameter together with pore dimension and overall scaffold roughness. Coagulation cascade activation, early platelet adhesion and activation were analyzed after two hours exposure of blood to the biomaterials. While no differences were found between DP and PLGA with similar topographies, the blood reactions were observed to be dependent on the fiber diameter and scaffold roughness. Scaffolds composed of thin fibers (diameter < 1μm) triggered very low coagulation and almost no platelet adhered. On the other hand, scaffold with bigger fiber diameter (2-3 μm) triggered higher thrombin formation and more platelets adhered. The highest platelet adhesion and activations rates as well as coagulation cascade activation were found in blood incubated in contact to the scaffolds produced with the biggest fiber diameter (5μm). These findings might indicate that electrospun grafts with small fiber diameter (<1μm) could perform better with a reduced early thrombogenicity by lower platelets adhesion and lower activation of platelets and coagulation cascade

The protocadherin 17 gene affects cognition, personality, amygdala structure and function, synapse development and risk of major mood disorders

Major mood disorders, which primarily include bipolar disorder and major depressive disorder, are the leading cause of disability worldwide and pose a major challenge in identifying robust risk genes. Here, we present data from independent large-scale clinical data sets (including 29 557 cases and 32 056 controls) revealing brain expressed protocadherin 17 (PCDH17) as a susceptibility gene for major mood disorders. Single-nucleotide polymorphisms (SNPs) spanning the PCDH17 region are significantly associated with major mood disorders; subjects carrying the risk allele showed impaired cognitive abilities, increased vulnerable personality features, decreased amygdala volume and altered amygdala function as compared with non-carriers. The risk allele predicted higher transcriptional levels of PCDH17 mRNA in postmortem brain samples, which is consistent with increased gene expression in patients with bipolar disorder compared with healthy subjects. Further, overexpression of PCDH17 in primary cortical neurons revealed significantly decreased spine density and abnormal dendritic morphology compared with control groups, which again is consistent with the clinical observations of reduced numbers of dendritic spines in the brains of patients with major mood disorders. Given that synaptic spines are dynamic structures which regulate neuronal plasticity and have crucial roles in myriad brain functions, this study reveals a potential underlying biological mechanism of a novel risk gene for major mood disorders involved in synaptic function and related intermediate phenotypes

Genome-wide association study of panic disorder reveals genetic overlap with neuroticism and depression

Panic disorder (PD) has a lifetime prevalence of 2–4% and heritability estimates of 40%. The contributory genetic variants remain largely unknown, with few and inconsistent loci having been reported. The present report describes the largest genome-wide association study (GWAS) of PD to date comprising genome-wide genotype data of 2248 clinically well-characterized PD patients and 7992 ethnically matched controls. The samples originated from four European countries (Denmark, Estonia, Germany, and Sweden). Standard GWAS quality control procedures were conducted on each individual dataset, and imputation was performed using the 1000 Genomes Project reference panel. A meta-analysis was then performed using the Ricopili pipeline. No genome-wide significant locus was identified. Leave-one-out analyses generated highly significant polygenic risk scores (PRS) (explained variance of up to 2.6%). Linkage disequilibrium (LD) score regression analysis of the GWAS data showed that the estimated heritability for PD was 28.0–34.2%. After correction for multiple testing, a significant genetic correlation was found between PD and major depressive disorder, depressive symptoms, and neuroticism. A total of 255 single-nucleotide polymorphisms (SNPs) with p < 1 × 10−4 were followed up in an independent sample of 2408 PD patients and 228,470 controls from Denmark, Iceland and the Netherlands. In the combined analysis, SNP rs144783209 showed the strongest association with PD (pcomb = 3.10 × 10−7). Sign tests revealed a significant enrichment of SNPs with a discovery p-value of <0.0001 in the combined follow up cohort (p = 0.048). The present integrative analysis represents a major step towards the elucidation of the genetic susceptibility to PD