scholarly journals Ecosystem Screening Approach for Pathogen-Associated Microorganisms Affecting Host Disease

2011 ◽  
Vol 77 (17) ◽  
pp. 6069-6075 ◽  
Author(s):  
Eric Galiana ◽  
Antoine Marais ◽  
Catherine Mura ◽  
Benoît Industri ◽  
Gilles Arbiol ◽  
...  
Keyword(s):  
Microbial Community ◽  
Screening Method ◽  
Surface Shape ◽  
Host Disease ◽  
Content Type ◽  
Mutualistic Interaction ◽  
Definition Of ◽  
Associated Species

ABSTRACTThe microbial community in which a pathogen evolves is fundamental to disease outcome. Species interacting with a pathogen on the host surface shape the distribution, density, and genetic diversity of the inoculum, but the role of these species is rarely determined. The screening method developed here can be used to characterize pathogen-associated species affecting disease. This strategy involves three steps: (i) constitution of the microbial community, using the pathogen as a trap; (ii) community selection, using extracts from the pathogen as the sole nutrient source; and (iii) molecular identification and the screening of isolates focusing on their effects on the growth of the pathogenin vitroand host disease. This approach was applied to a soilborne plant pathogen,Phytophthora parasitica, structured in a biofilm, for screening the microbial community from the rhizosphere ofNicotiana tabacum(the host). Two of the characterized eukaryotes interfered with the oomycete cycle and may affect the host disease. AVorticellaspecies acted through a mutualistic interaction withP. parasitica, disseminating pathogenic material by leaving the biofilm. APhomaspecies established an amensal interaction withP. parasitica, strongly suppressing disease by inhibitingP. parasiticagermination. This screening method is appropriate for all nonobligate pathogens. It allows the definition of microbial species as promoters or suppressors of a disease for a given biotope. It should also help to identify important microbial relationships for ecology and evolution of pathogens.

An integrated screening method for evaluating the pulmonary toxicity of inhaled particulates: Role of microscopic techniques in assessing pulmonary macrophage clearance functions

1990 ◽  
Vol 48 (3) ◽  
pp. 826-827
Author(s):  
David B. Warheit ◽  
Lena Achinko ◽  
Mark A. Hartsky
Keyword(s):  
Bronchoalveolar Lavage ◽  
Pulmonary Toxicity ◽  
Screening Method ◽  
Pulmonary Response ◽  
Inhaled Particles ◽  
Cytochemical Analysis ◽  
Pulmonary Macrophages ◽  
Integrated Screening

There is a great need for the development of a rapid and reliable bioassay to evaluate the pulmonary toxicity of inhaled particles. A number of methods have been proposed, including lung clearance studies, bronchoalveolar lavage analysis, and in vitro cytotoxicity tests. These methods are often limited in scope inasmuch as they measure only one dimension of the pulmonary response to inhaled, instilled or incubated dusts. Accordingly, a comprehensive approach to lung toxicity studies has been developed.To validate the method, rats were exposed for 6 hours or 3 days to various concentrations of either aerosolized alpha quartz silica (Si) or carbonyl iron (CI) particles. Cells and fluids from groups of sham and dust-exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, LDH and protein values were measured in BAL fluids at several time points postexposure. Cells were counted and evaluated for viability, as well as differential and cytochemical analysis. In addition, pulmonary macrophages (PM) were cultured and studied for morphology, chemotaxis, and phagocytosis by scanning electron microscopy.

scholarly journals Spontaneous Gac Mutants of Pseudomonas Biological Control Strains: Cheaters or Mutualists?

2011 ◽  
Vol 77 (20) ◽  
pp. 7227-7235 ◽  
Author(s):  
William W. Driscoll ◽  
John W. Pepper ◽  
Leland S. Pierson ◽  
Elizabeth A. Pierson
Keyword(s):  
Alternative Hypothesis ◽  
Natural Populations ◽  
Regulatory System ◽  
Wild Type ◽  
Content Type ◽  
The Public ◽  
Extracellular Metabolites ◽  
Mutualistic Interaction ◽  
Alternative Hypotheses

ABSTRACTBacteria rely on a range of extracellular metabolites to suppress competitors, gain access to resources, and exploit plant or animal hosts. The GacS/GacA two-component regulatory system positively controls the expression of many of these beneficial external products in pseudomonad bacteria. Natural populations often contain variants with defective Gac systems that do not produce most external products. These mutants benefit from a decreased metabolic load but do not appear to displace the wild type in nature. How could natural selection maintain the wild type in the presence of a mutant with enhanced growth? One hypothesis is that Gac mutants are “cheaters” that do not contribute to the public good, favored within groups but selected against between groups, as groups containing more mutants lose access to ecologically important external products. An alternative hypothesis is that Gac mutants have a mutualistic interaction with the wild type, so that each variant benefits by the presence of the other. In the biocontrol bacteriumPseudomonas chlororaphisstrain 30-84, Gac mutants do not produce phenazines, which suppress competitor growth and are critical for biofilm formation. Here, we test the predictions of these alternative hypotheses by quantifying interactions between the wild type and the phenazine- and biofilm-deficient Gac mutant within growing biofilms. We find evidence that the wild type and Gac mutants interact mutualistically in the biofilm context, whereas a phenazine-defective structural mutant does not. Our results suggest that the persistence of alternative Gac phenotypes may be due to the stabilizing role of local mutualistic interactions.

scholarly journals Drug Susceptibility Distributions of Mycobacterium chimaera and Other Nontuberculous Mycobacteria

2021 ◽  
Vol 65 (5) ◽  
Author(s):  
Bettina Schulthess ◽  
Daniel Schäfle ◽  
Nicole Kälin ◽  
Tamara Widmer ◽  
Peter Sander
Keyword(s):  
Antibiotic Susceptibility ◽  
Nontuberculous Mycobacteria ◽  
Drug Susceptibility ◽  
Species Differentiation ◽  
Content Type ◽  
Susceptibility Data ◽  
Clinical Breakpoints ◽  
Antibiotic Susceptibility Patterns ◽  
Definition Of

ABSTRACT Recent outbreaks of cardiac surgery-associated Mycobacterium chimaera infections have highlighted the importance of species differentiation within the Mycobacterium avium complex and pointed to a lack of antibiotic susceptibility data for M. chimaera. Using the MGIT 960/EpiCenter TB eXiST platform, we have determined antibiotic susceptibility patterns of 48 clinical M. chimaera isolates and 139 other nontuberculous mycobacteria, including 119 members of the M. avium complex and 20 Mycobacterium kansasii isolates toward clofazimine and other drugs used to treat infections with slow-growing nontuberculous mycobacteria (NTM). MIC50, MIC90, and tentative epidemiological cutoff (ECOFF) values for clofazimine were 0.5 mg/liter, 1 mg/liter, and 2 mg/liter, respectively, for M. chimaera. Comparable values were observed for other M. avium complex members, whereas lower MIC50 (≤0.25 mg/liter), MIC90 (0.5 mg/liter), and ECOFF (1 mg/liter) values were found for M. kansasii. Susceptibility to clarithromycin, ethambutol, rifampin, rifabutin, amikacin, moxifloxacin, and linezolid was in general similar for M. chimaera and other members of the M. avium complex, but increased for M. kansasii. The herein determined MIC distributions, MIC90, and ECOFF values of clofazimine for M. chimaera and other NTM provide the basis for the definition of clinical breakpoints. Further studies are needed to establish correlation of in vitro susceptibility and clinical outcome.

scholarly journals Activity of the Pore-Forming Virulence Factor Listeriolysin O Is Reversibly Inhibited by Naturally Occurring S-Glutathionylation

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Jonathan L. Portman ◽  
Qiongying Huang ◽  
Michelle L. Reniere ◽  
Anthony T. Iavarone ◽  
Daniel A. Portnoy
Keyword(s):  
Protein Function ◽  
Inhibitory Effect ◽  
Cysteine Residue ◽  
Infection Model ◽  
Listeriolysin O ◽  
Content Type ◽  
Pore Forming Proteins

ABSTRACT Cholesterol-dependent cytolysins (CDCs) represent a family of homologous pore-forming proteins secreted by many Gram-positive bacterial pathogens. CDCs mediate membrane binding partly through a conserved C-terminal undecapeptide, which contains a single cysteine residue. While mutational changes to other residues in the undecapeptide typically have severe effects, mutation of the cysteine residue to alanine has minor effects on overall protein function. Thus, the role of this highly conserved reactive cysteine residue remains largely unknown. We report here that the CDC listeriolysin O (LLO), secreted by the facultative intracellular pathogen Listeria monocytogenes, was posttranslationally modified by S-glutathionylation at this conserved cysteine residue and that either endogenously synthesized or exogenously added glutathione was sufficient to form this modification. When recapitulated with purified protein in vitro, this modification completely ablated the activity of LLO, and this inhibitory effect was fully reversible by treatment with reducing agents. A cysteine-to-alanine mutation in LLO rendered the protein completely resistant to inactivation by S-glutathionylation, and a mutant expressing this mutation retained full hemolytic activity. A mutant strain of L. monocytogenes expressing the cysteine-to-alanine variant of LLO was able to infect and replicate within bone marrow-derived macrophages indistinguishably from the wild type in vitro, yet it was attenuated 4- to 6-fold in a competitive murine infection model in vivo. This study suggests that S-glutathionylation may represent a mechanism by which CDC-family proteins are posttranslationally modified and regulated and help explain an evolutionary pressure to retain the highly conserved undecapeptide cysteine.

scholarly journals Extending the Definition of the GyrB Quinolone Resistance-Determining Region in Mycobacterium tuberculosis DNA Gyrase for Assessing Fluoroquinolone Resistance in M. tuberculosis

2012 ◽  
Vol 56 (4) ◽  
pp. 1990-1996 ◽  
Author(s):  
Alix Pantel ◽  
Stéphanie Petrella ◽  
Nicolas Veziris ◽  
Florence Brossier ◽  
Sylvaine Bastian ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Hot Spot ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Fluoroquinolone Resistance ◽  
Wild Type ◽  
Content Type ◽  
Highly Active ◽  
Definition Of

ABSTRACTFluoroquinolone (FQ) resistance is emerging inMycobacterium tuberculosis. The main mechanism of FQ resistance is amino acid substitution within the quinolone resistance-determining region (QRDR) of the GyrA subunit of DNA gyrase, the sole FQ target inM. tuberculosis. However, substitutions in GyrB whose implication in FQ resistance is unknown are increasingly being reported. The present study clarified the role of four GyrB substitutions identified inM. tuberculosisclinical strains, two located in the QRDR (D500A and N538T) and two outside the QRDR (T539P and E540V), in FQ resistance. We measured FQ MICs and also DNA gyrase inhibition by FQs in order to unequivocally clarify the role of these mutations in FQ resistance. Wild-type GyrA, wild-type GyrB, and mutant GyrB subunits produced from engineeredgyrBalleles by mutagenesis were overexpressed inEscherichia coli, purified to homogeneity, and used to reconstitute highly active gyrase complexes. MICs and DNA gyrase inhibition were determined for moxifloxacin, gatifloxacin, ofloxacin, levofloxacin, and enoxacin. All these substitutions are clearly implicated in FQ resistance, underlining the presence of a hot spot region housing most of the GyrB substitutions implicated in FQ resistance (residues NTE, 538 to 540). These findings help us to refine the definition of GyrB QRDR, which is extended to positions 500 to 540.

Isolation and characterization of calcifying bacteria from “living rocks”: a possible carbon sink

2021 ◽  
Author(s):  
Maddalena del Gallo ◽  
Amedeo Mignini ◽  
Giulio Moretti ◽  
Marika Pellegrini ◽  
Paola Cacchio
Keyword(s):  
Calcium Carbonate ◽  
Carbon Sink ◽  
In Vitro Regeneration ◽  
Scientific Basis ◽  
16S Rrna Analysis ◽  
Environmental Threats ◽  
Isolation And Characterization ◽  
Definition Of

<p>CO<sub>2</sub> emissions triggered by anthropogenic and natural activities contribute to climate change, one of the current environmental threats of public and scientific concern. At present, microbially-induced biomineralization of CO<sub>2</sub> by calcium carbonate (CaCO<sub>3</sub>) is one of the highly topical study subjects as carbon stabilization process. In the present study we focused our attention on the calcifying bacteria of “living rocks”. The origin of these concretions, composed by a silicate skeleton of quartz and feldspars, merged by massive carbonate concrete, has so far been recognized as abiotic. Within this study we investigated the role of calcifying bacteria in their formation of these concretions and we isolated and characterized the species with CaCO<sub>3</sub> precipitation abilities. Concretions were sampled in Romania (Trovant) and Italy (Sibari and Rome). Samples were first analyzed for their culturable microflora (i.e. isolation, CaCO<sub>3 </sub>precipitation capability and molecular characterization). Then, in vitro regeneration tests were carried out to confirm the contribution of bacteria in the formation of these erratic masses. Moreover, natural samples and bioliths regenerated in vitro were (i) observed and analyzed by scanning electron microscopy (SEM-EDS) and (ii) characterized at molecular level by DNA extraction and 16S rRNA analysis (V3-V4 regions). By isolating and characterizing the culturable microflora, we obtained 19 calcifying isolates, with different morphological, bacteriological and mineral precipitation properties. These evidences have given a first relevant contribution for the definition of the biotic role to the formation of these concretions. These evidences were confirmed by the efficient in vitro regeneration and SEM-EDS analysis. The molecular identification of the isolates and the comparison of the data obtained from the Illumina sequencing with those present in the literature, allowed us to hypothesize the genera that most likely contributed to the formation of these concretions. The results obtained provide a good scientific basis for further studies, which should be directed towards the use of isolates in studies of environmental and socio-economic relevance. Several studies demonstrate that microbially mediated biomineralization has the potential to capture and sequester carbon. Calcium carbonate, is a stable pool of carbon and is an effective sealant to prevent CO<sub>2</sub> release back into the atmosphere.</p>

scholarly journals Academic excellence as “competitiveness enhancement” in Russian higher education

2019 ◽  
Vol 21 (2) ◽  
pp. 127-144 ◽  
Author(s):  
Elena Tsvetkova ◽  
Sylvie Lomer
Keyword(s):  
Higher Education ◽  
Critical Discourse Analysis ◽  
Academic Excellence ◽  
Content Type ◽  
World University Rankings ◽  
Russian Higher Education ◽  
The Government ◽  
Definition Of ◽  
Russian Universities

Purpose The purpose of this paper is to analyse critically the Russian Academic Excellence Initiative (the Project 5-100), designed to propel five leading Russian universities into world university rankings (WURs) by 2020, and research it through the lens of neoliberalism. The paper seeks to reveal recurrent discourses and dominant orders of discourse constituting the overall concept of “excellence” in Russian higher education (HE) policy. Design/methodology/approach Since the Project 5-100 has been designed in line with a neoliberal model of academic excellence initiatives, emphasising “competition as a driver of excellence” (Hazelkorn, 2009), Fairclough’s approach to critical discourse analysis (CDA) has been adopted as a qualitative research method. There is no universally accepted definition of “excellence” in HE policy; therefore, this CDA also aims at revealing the Russian government’s vision of the concept and its voice in HE policy. Findings The paper concludes that the government reinforces neoliberal discourse on the HE agenda and transforms the 5-100 Universities’ identities through emphasising the role of WURs in modernising the HE system. Consequently, within the neoliberal paradigm, the Project 5-100 can be regarded as a manifestation of the commodification of “excellence” in Russian HE policy. Originality/value This research intends to broaden knowledge of excellence initiatives in HE policy and reveal their features and neoliberal natures. It also seeks to contribute in terms of showcasing a qualitative study of the Project 5-100 for future comparative analyses of similar HE policies.

Connecting universities with entrepreneurship through digital learning platform: functional requirements and education-based knowledge exchange activities

2020 ◽  
Vol 26 (7) ◽  
pp. 1525-1545 ◽  
Author(s):  
Roberto Linzalone ◽  
Giovanni Schiuma ◽  
Salvatore Ammirato
Keyword(s):  
Knowledge Exchange ◽  
Digital Learning ◽  
Functional Requirements ◽  
Learning Space ◽  
Case Study Methodology ◽  
Content Type ◽  
Learning Platform ◽  
Learning Platforms ◽  
Definition Of

PurposeStudies on academic entrepreneurship (AE) agree on the significant impact that Universities can have on entrepreneurial development. AE deploys through fundamental activities, like the start-up of new companies and the connection of the University with Enterprises. The purpose of this paper is to analyse the role of digital learning platforms (DLP) to connect Universities and Enterprises effectively. Although the literature has extensively investigated DLP, there is a lack of understanding of the role of DLP in supporting digital AE. This paper focuses, in particular, on the functional requirements that have to distinguish the development of DLPs supporting education-based activities of knowledge transfer between academia and enterprise.Design/methodology/approachThe research is carried out, adopting a case study methodology. A single and holistic case regarding a DLP developed for the strategic and exclusive deployment of AE activities is proposed to describe and discuss the functional requirements of such Platform.FindingsThe DLP is a virtual learning space in which Enterprises and Universities can interact. The definition of design requirements is crucial for the efficacy of DLPs and needs to be carefully supported. Various criteria are proposed, respect to the various stakeholders engaged in DAE learning platform (Universities, Enterprises, students, employees), and according to the short- and long-term objectives of Universities and Entrepreneurship connection.Originality/valueThe paper explores an original case of DLP established in AE, to connect Universities and Enterprises. The research also sheds light on the under focussed typology of AE activities regarding education-based knowledge exchange. They are currently unaddressed by the literature on AE.

Social participation in the definition of budgetary instruments

2020 ◽  
Vol 14 (5) ◽  
pp. 737-755
Author(s):  
Luiz Antonio Felix Júnior ◽  
Wênyka Preston Leite Batista da Costa ◽  
Luciana Gondim de Almeida Guimarães ◽  
Glauber Ruan Barbosa Pereira ◽  
Walid Abbas El-Aouar
Keyword(s):  
Social Participation ◽  
Smart City ◽  
Essential Element ◽  
Popular Participation ◽  
Content Type ◽  
The Public ◽  
The Social ◽  
Public Resources ◽  
Definition Of

Purpose The participation of society is a valuable aspect of the governability of cities, for it strengthens the citizens’ collaborative component. Such participation, which is seen as social, is considered an essential element for the design of a smart city. This study aims to identify the factors that contribute to social participation in the definition of budgetary instruments’ planning. Design/methodology/approach Concerning the methodological instruments, this study is characterised by a quantitative and descriptive approach and uses a multivariate data analysis with a sample of 235 respondents. Findings The study’s findings identified a framework that portrays elements that collaborate with the social participation in the definition of the public administration’s budgetary instruments, which are considered as elements that are able to develop the role of the popular participation and are characterised by the definition of a smart city by enabling more assertiveness in society’s needs. Practical implications Identification of a framework that brings out elements that are able to develop the popular participation in the definition of budgetary instruments. Then, one scale of elements that contribute to social participation in the definition of the public administration’s budgetary instruments theoretically represented and statistically validated, thus contributing to the continuity of studies on social participation. Social implications Through studies on social participation in budgetary planning, it is possible to guarantee a better allocation of public resources through intelligent governability. Originality/value The research can bring theoretical elements about social participation in the definition of budget instruments for a statistical convergence through the perception of the sample.

scholarly journals Fimbria-Encoding GeneyadCHas a Pleiotropic Effect on Several Biological Characteristics and Plays a Role in Avian Pathogenic Escherichia coli Pathogenicity

2015 ◽  
Vol 84 (1) ◽  
pp. 187-193 ◽  
Author(s):  
Renu Verma ◽  
Thaís Cabrera Galvão Rojas ◽  
Renato Pariz Maluta ◽  
Janaína Luisa Leite ◽  
Livia Pilatti Mendes da Silva ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Soft Agar ◽  
Pleiotropic Effect ◽  
Biological Characteristics ◽  
Wild Type ◽  
Content Type ◽  
Pathogenic Escherichia Coli

The extraintestinal pathogen termed avian pathogenicEscherichia coli(APEC) is known to cause colibacillosis in chickens. The molecular basis of APEC pathogenesis is not fully elucidated yet. In this work, we deleted a component of the Yad gene cluster (yadC) in order to understand the role of Yad in the pathogenicity of the APEC strain SCI-07.In vitro, the transcription level ofyadCwas upregulated at 41°C and downregulated at 22°C. TheyadCexpressionin vivowas more pronounced in lungs than in spleen, suggesting a role in the early steps of the infection. Chicks infected with the wild-type and mutant strains presented, respectively, 80% and 50% mortality rates. The ΔyadCstrain presented a slightly decreased ability to adhere to HeLa cells with or without thed-mannose analog compared with the wild type. Real-time PCR (RT-PCR) assays showed thatfimHwas downregulated (P< 0.05) andcsgAandecpAwere slightly upregulated in the mutant strain, showing thatyadCmodulates expression of other fimbriae. Bacterial internalization studies showed that the ΔyadCstrain had a lower number of intracellular bacteria recovered from Hep-2 cells and HD11 cells than the wild-type strain (P< 0.05). Motility assays in soft agar demonstrated that the ΔyadCstrain was less motile than the wild type (P< 0.01). Curiously, flagellum-associated genes were not dramatically downregulated in the ΔyadCstrain. Taken together, the results show that the fimbrial adhesin Yad contributes to the pathogenicity and modulates different biological characteristics of the APEC strain SCI-07.

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