Laser-induced fluorescence study of OH in flat flames of 1–10 bar compared with resonance CARS experiments

Kohse-Höinghaus K, Meier U, Attal-Trétout B. Laser-induced fluorescence study of OH in flat flames of 1–10 bar compared with resonance CARS experiments. Applied Optics. 1990;29(10):1560-1569.Laser-induced fluorescence (LIF) measurements of OH were performed in flat stoichiometric CH4/air flames burning at 1, 3, 5, 7, and 9.6 bar, which had previously been investigated using OH resonance CARS. In the LIF study, line shape information and temperatures were extracted from excitation spectra; in addition, OH profiles as a function of height above the burner surface and an estimate of the OH concentration for the different flames were obtained. The perspectives and feasibility of quantitative fluorescence measurements in high pressure flames are discussed, particularly in comparison with the application of resonance CARS

L’eau à Damas et dans son environnement rural au xviiie siècle

Le système hydraulique qui alimente la ville de Damas et son environnement rural est très ancien. Mais il est en constante évolution et l’on peut difficilement accréditer l’idée de son caractère immuable. À partir de diverses sources juridiques, cet article s’interroge sur les règles, les pratiques et les procédures administratives et juridiques qui sont en vigueur dans le domaine de la distribution de l’eau à Damas et dans sa campagne au xviiie siècle. Il montre le rôle des autorités juridiques et politiques dans l’entretien du système hydraulique et examine leurs interventions dans les conflits qui opposent les divers ayants droit.The hydraulic systems that supplied the city of Damascus and its rural hinterland are obviously ancient, they are however constant evolutions. Therefore it seems difficult to assume that water supply system immutability. Based on a variety of juridical sources, the aim of this article is to clarify the rules, practices and the administrative/juridical procedures that structured the water distribution in Damascus and its dependent countryside during the 18th century. The enquiry sheds light on the role of the judicial and political authorities in the maintenance of the hydraulic systems and examines how they intervened in various conflicts that involved different parties.إن النظام المائي الذي يغذّي مدينة دمشق ومحيطها الريفي قديم جًّدا. إلا أنه في تطور مستمر ومن الصعوبة تأكيد فكرة كونه ثابتاً لا يتغيّر. انطلاقاً من مصادر فقهية متنوعة، تطرح هذه المقالة تساؤلاتٍ عن القواعد والممارسات والإجراءات الإدارية والفقهية المَرعية في مجال توزيع المياه في دمشق وريفها في القرن الثامن عشر. تبين هذه المقالة دور السلطات القانونية والسياسية في الاعتناء بالنظام المائي وتدرس بإمعان تدخلاتها في النزاعات الناشئة بين أصحاب الحق في الماء

High Diversity of Diazotrophs in the Forefield of a Receding Alpine Glacier

Forefields of receding glaciers are unique and sensitive environments representing natural chronosequences. In such habitats, microbial nitrogen fixation is of particular interest since the low concentration of bioavailable nitrogen is one of the key limitations for growth of plants and soil microorganisms. Asymbiotic nitrogen fixation in the Damma glacier (Swiss Central Alps) forefield soils was assessed using the acetylene reduction assay. Free-living diazotrophic diversity and population structure were resolved by assembling four NifH sequence libraries for bulk and rhizosphere soils at two soil age classes (8- and 70-year ice-free forefield). A total of 318 NifH sequences were analyzed and grouped into 45 unique phylotypes. Phylogenetic analyses revealed a higher diversity as well as a broader distribution of NifH sequences among phylogenetic clusters than formerly observed in other environments. This illustrates the importance of free-living diazotrophs and their potential contribution to the global nitrogen input in this nutrient-poor environment. NifH diversity in bulk soils was higher than in rhizosphere soils. Moreover, the four libraries displayed low similarity values. This indicated that both soil age and the presence of pioneer plants influence diversification and population structure of free-living diazotroph

Phylogenetic distribution and membrane topology of the LytR-CpsA-Psr protein family

BACKGROUND: The bacterial cell wall is the target of many antibiotics and cell envelope constituents are critical to host-pathogen interactions. To combat resistance development and virulence, a detailed knowledge of the individual factors involved is essential. Members of the LytR-CpsA-Psr family of cell envelope-associated attenuators are relevant for beta-lactam resistance, biofilm formation, and stress tolerance, and they are suggested to play a role in cell wall maintenance. However, their precise function is still unknown. This study addresses the occurrence as well as sequence-based characteristics of the LytR-CpsA-Psr proteins. RESULTS: A comprehensive list of LytR-CpsA-Psr proteins was established, and their phylogenetic distribution and clustering into subgroups was determined. LytR-CpsA-Psr proteins were present in all Gram-positive organisms, except for the cell wall-deficient Mollicutes and one strain of the Clostridiales. In contrast, the majority of Gram-negatives did not contain LytR-CpsA-Psr family members. Despite high sequence divergence, the LytR-CpsA-Psr domains of different subclusters shared a highly similar, predicted mixed alpha/beta-structure, and conserved charged residues. PhoA fusion experiments, using MsrR of Staphylococcus aureus, confirmed membrane topology predictions and extracellular location of its LytR-CpsA-Psr domain. CONCLUSIONS: The LytR-CpsA-Psr domain is unique to bacteria. The presence of diverse subgroups within the LytR-CpsA-Psr family might indicate functional differences, and could explain variations in phenotypes of respective mutants reported. The identified conserved structural elements and amino acids are likely to be important for the function of the domain and will help to guide future studies of the LytR-CpsA-Psr proteins

Induction kinetics of the Staphylococcus aureus cell wall stress stimulon in response to different cell wall active antibiotics

BACKGROUND: Staphylococcus aureus activates a protective cell wall stress stimulon (CWSS) in response to the inhibition of cell wall synthesis or cell envelope damage caused by several structurally and functionally different antibiotics. CWSS induction is coordinated by the VraSR two-component system, which senses an unknown signal triggered by diverse cell wall active agents. RESULTS: We have constructed a highly sensitive luciferase reporter gene system, using the promoter of sas016 (S. aureus N315), which detects very subtle differences in expression as well as measuring > 4 log-fold changes in CWSS activity, to compare the concentration dependence of CWSS induction kinetics of antibiotics with different cell envelope targets. We compared the effects of subinhibitory up to suprainhibitory concentrations of fosfomycin, D-cycloserine, tunicamycin, bacitracin, flavomycin, vancomycin, teicoplanin, oxacillin, lysostaphin and daptomycin. Induction kinetics were both strongly antibiotic- and concentration-dependent. Most antibiotics triggered an immediate response with induction beginning within 10 min, except for tunicamycin, D-cycloserine and fosfomycin which showed lags of up to one generation before induction commenced. Induction characteristics, such as the rate of CWSS induction once initiated and maximal induction reached, were strongly antibiotic dependent. We observed a clear correlation between the inhibitory effects of specific antibiotic concentrations on growth and corresponding increases in CWSS induction kinetics. Inactivation of VraR increased susceptibility to the antibiotics tested from 2- to 16-fold, with the exceptions of oxacillin and D-cycloserine, where no differences were detected in the methicillin susceptible S. aureus strain background analysed. There was no apparent correlation between the induction capacity of the various antibiotics and the relative importance of the CWSS for the corresponding resistance phenotypes. CONCLUSION: CWSS induction profiles were unique for each antibiotic. Differences observed in optimal induction conditions for specific antibiotics should be determined and taken into account when designing and interpreting CWSS induction studies

MsrR contributes to cell surface characteristics and virulence in Staphylococcus aureus

MsrR, a factor contributing to methicillin resistance in Staphylococcus aureus, belongs to the LytR-CpsA-Psr family of cell envelope-associated proteins. Deletion of msrR increased cell size and aggregation, and altered envelope properties, leading to a temporary reduction in cell surface hydrophobicity, diminished colony-spreading ability, and an increased susceptibility to Congo red. The reduced phosphorus content of purified cell walls of the msrR mutant suggested a reduction in wall teichoic acids, which may explain some of the observed phenotypes. Microarray analysis of the msrR deletion mutant revealed only minor changes in the global transcriptome, suggesting that MsrR has structural rather than regulatory functions. Importantly, virulence of the msrR mutant was decreased in a nematode-killing assay as well as in rat experimental endocarditis. MsrR is therefore likely to play a role in cell envelope maintenance, cell separation, and pathogenicity of S. aureu

LytR-CpsA-Psr proteins in Staphylococcus aureus display partial functional redundancy and the deletion of all three severely impairs septum placement and cell separation

Staphylococcus aureus contains three members of the LytR-CpsA-Psr (LCP) family of membrane proteins: MsrR, SA0908 and SA2103. The characterization of single-, double- and triple-deletion mutants revealed distinct phenotypes for each of the three proteins. MsrR was involved in cell separation and septum formation and influenced β-lactam resistance; SA0908 protected cells from autolysis; and SA2103, although displaying no apparent phenotype by itself, enhanced the properties of msrR and sa0908 mutants when deleted. The deletion of sa0908 and sa2103 also further attenuated the virulence of msrR mutants in a nematode-killing assay. The severely defective growth phenotype of the triple mutant revealed that LytR-CpsA-Psr proteins are essential for optimal cell division in S. aureus. Growth could be rescued to varying degrees by any one of the three proteins, indicating some functional redundancy within members of this protein family. However, differing phenotypic characteristics of all single and double mutants and complemented triple mutants indicated that each protein played a distinct role(s) and contributed differently to phenotypes influencing cell separation, autolysis, cell surface properties and virulenc

Deletion of hypothetical wall teichoic acid ligases in Staphylococcus aureus activates the cell wall stress response

The Staphylococcus aureus cell wall stress stimulon (CWSS) is activated by cell envelope-targeting antibiotics or depletion of essential cell wall biosynthesis enzymes. The functionally uncharacterized S. aureus LytR-CpsA-Psr (LCP) proteins, MsrR, SA0908 and SA2103, all belong to the CWSS. Although not essential, deletion of all three LCP proteins severely impairs cell division. We show here that VraSR-dependent CWSS expression was up to 250-fold higher in single, double and triple LCP mutants than in wild type S. aureus in the absence of external stress. The LCP triple mutant was virtually depleted of wall teichoic acids (WTA), which could be restored to different degrees by any of the single LCP proteins. Subinhibitory concentrations of tunicamycin, which inhibits the first WTA synthesis enzyme TarO (TagO), could partially complement the severe growth defect of the LCP triple mutant. Both of the latter findings support a role for S. aureus LCP proteins in late WTA synthesis, as in Bacillus subtilis where LCP proteins were recently proposed to transfer WTA from lipid carriers to the cell wall peptidoglycan. Intrinsic activation of the CWSS upon LCP deletion and the fact that LCP proteins were essential for WTA-loading of the cell wall, highlight their important role(s) in S. aureus cell envelope biogenesi

Gesundheitswirtschaft in OstWestfalenLippe: Stärken, Chancen und Gestaltungsmöglichkeiten

"Die Gesundheitswirtschaft zählt zu den zentralen Kompetenzbereichen der Region OstWestfalenLippe. Zu diesem Ergebnis kommt die 'Potenzialanalyse OWL – Branchen, Kompetenzen, Perspektiven', die im Auftrag der Initiative für Beschäftigung OWL e.V. und der Bezirksregierung Detmold erstellt und deren Ergebnisse auf der Regionalkonferenz diskutiert wurden. In der Studie heißt es: 'Der Anteil des Gesundheitswesens in OWL liegt leicht über dem NRW-Durchschnitt. Das ist bemerkenswert für eine Branche, die ansonsten räumlich sehr breit gestreut und gleich verteilt ist. In den einzelnen Segmenten des Gesundheitswesens und auch in den damit zusammenhängenden Branchen finden sich in OWL starke Kompetenzen: vor allem in den Kurorten und Kliniken der Region, in der ambulanten Versorgung und in der Medizintechnik und den medizinischen Hilfsmitteln. Diese Kompetenzen werden zukünftig dann erheblich an Bedeutung gewinnen, wenn es gelingt, die anstehenden Umstrukturierungen in der Gesundheitswirtschaft als Chance für eine wirtschaftliche Modernisierung zu nutzen' (Rehfeld/Fernandez-Sanchez 2003)." (Textauszug