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Fragmentation of extracellular DNA by long-term exposure to radiation from uranium in aquatic environments

Arruda Neto, Joao Dias de Toledo; Nieto-González, Luis; Righi, Henriette; Cotta, Mônica Alonso; Carrer, Helaine; Rodrigues, Tulio Eduardo; Genofre Netto, Godofredo da Camara
Fonte: ROYAL SOC CHEMISTRY; CAMBRIDGE Publicador: ROYAL SOC CHEMISTRY; CAMBRIDGE
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.11%
Persistent harmful scenarios associated with disposal of radioactive waste, high-background radiation areas and severe nuclear accidents are of great concern regarding consequences to both human health and the environment. Of particular concern is the extracellular DNA in aquatic environments contaminated by radiological substances. Strand breaks induced by radiation promote decrease in the transformation efficiency for extracellular DNA. The focus of this study is the quantification of DNA damage following long-term exposure (over one year) to low doses of natural uranium (an alpha particle emitter) to simulate natural conditions, since nothing is known about alpha radiation induced damage to extracellular DNA. A high-resolution Atomic Force Microscope was used to evaluate DNA fragments. Double-stranded plasmid pBS as a model for extracellular DNA was exposed to different amounts of natural uranium. It was demonstrated that low concentrations of U in water (50 to 150 ppm) produce appreciable numbers of double strand breaks, scaling with the square of the average doses. The importance of these findings for environment monitoring of radiological pollution is addressed.; Brazilian agency FAPESP; FAPESP Brazilian agency; CNPq Brazilian agency; Brazilian agency CNPq

Influência da temperatura, de enzimas degradantes de DNA e do sobrenadante de cultura de estafilococos na formação de biofilme por Listeria monocytogenes em superfície abiótica; Influence of temperature, DNA degrading enzymes and staphylococcal culture supernatant on biofilm formation by Listeria monocytogenes on abiotic surface

Silva, Eliane Pereira da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/10/2012 PT
Relevância na Pesquisa
56.09%
A listeriose é uma infecção rara e grave, transmitida principalmente por alimentos. É causada pela bactéria Listeria monocytogenes e acomete principalmente mulheres grávidas e pessoas comprometidas imunologicamente. Este patógeno é reconhecido como um problema para as indústrias de alimentos devido à sua capacidade em formar biofilmes. Os biofilmes são comunidades microbianas aderidas a superfícies bióticas ou abióticas embebidas em uma matriz de polímeros extracelulares produzidos pelas próprias células. Estas estruturas são resistentes a procedimentos de higienização e desinfecção, contribuindo para a persistência de L. monocytogenes em ambientes processadores de alimentos. Desta forma, há grande interesse em estratégias para prevenir a formação de biofilmes por L. monocytogenes. No presente trabalho foi investigada a formação de biofilmes por L. monocytogenes em superfície abiótica, sob diferentes temperaturas, na presença de enzimas degradantes de DNA (DNAses) e na presença de sobrenadante de cultura de estafilococos com e sem atividade de DNAse termoestável (termonuclease). Foram utilizadas técnicas de cultivo e de microscopia e os resultados demonstraram que L. monocytogenes aderiu à superfície de aço inoxidável...

Fragmentation of extracellular DNA by long-term exposure to radiation from uranium in aquatic environments

Arruda-Neto, J. D. T.; Nieto, L.; Righi, H.; Cotta, M. A.; Carrer, H.; Rodrigues, T. E.; Genofre, G. C.
Fonte: Royal Society Of Chemistry; Cambridge Publicador: Royal Society Of Chemistry; Cambridge
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.1%
Persistent harmful scenarios associated with disposal of radioactive waste, high-background radiation areas and severe nuclear accidents are of great concern regarding consequences to both human health and the environment. Of particular concern is the extracellular DNA in aquatic environments contaminated by radiological substances. Strand breaks induced by radiation promote decrease in the transformation efficiency for extracellular DNA. The focus of this study is the quantification of DNA damage following long-term exposure (over one year) to low doses of natural uranium (an alpha particle emitter) to simulate natural conditions, since nothing is known about alpha radiation induced damage to extracellular DNA. A high-resolution Atomic Force Microscope was used to evaluate DNA fragments. Double-stranded plasmid pBS as a model for extracellular DNA was exposed to different amounts of natural uranium. It was demonstrated that low concentrations of U in water (50 to 150 ppm) produce appreciable numbers of double strand breaks, scaling with the square of the average doses. The importance of these findings for environment monitoring of radiological pollution is addressed.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Game and player : C. albicans biofilm lifestyle and extracellular DNA

Martins, Margarida; Uppuluri, Priya; Thomas, Derek P.; Cleary, Ian A.; Henriques, Mariana; Lopez-Ribot, José L.; Oliveira, Rosário
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2010 ENG
Relevância na Pesquisa
46.06%
DNA is as a structural component of bacterial biofilms extracellular matrix (ECM). Although evidences have shown that DNA may play a role in C. albicans biofilms, further studies are required to understand the contribution of extracellular DNA (eDNA) in C. albicans biofilm lifestyle. Herein we aimed to determine the eDNA content of C. albicans SC5314 biofilm ECM and the effect of DNase I and exogenous DNA treatments on biofilm formation and biofilm cells susceptibility to antifungals. First, for eDNA estimation in C. albicans biofilm ECM, biofilms were formed under flow conditions for 48 h. ECM was isolated and its DNA and protein contents were determined. Second, DNase (0.02 - 2 mg/ml) and exogenous DNA (10 - 2560 ng/ml) were added at different stages of biofilm development (microtiter plate model under static conditions). The effect of 24 h treatments was evaluated in terms of biofilm biomass by crystal violet assay (A550). Third, for antifungal testing, biofilms (in 96-well plates) were challenged with amphotericin B (0.06 - 16 mg/l), caspofungin (0.008 to 2 mg/l), and fluconazole (4 - 1024 mg/l) alone or in combination with DNase (0.125 mg/ml) or exogenous DNA (320 ng/ml). Sessile minimum inhibitory concentrations (SMIC) were determined at 80 % inhibition compared to drug-free controls using the XTT reduction assay. RPMI medium was used in all the assays. On one hand...

Presence of extracellular DNA in the Candida albicans biofilm matrix and its contribution to biofilms

Martins, M.; Uppuluri, Priya; Thomas, Derek P.; Cleary, Ian A.; Henriques, Mariana; Lopez-Ribot, José L.; Oliveira, Rosário
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
66.09%
DNA has been described as a structural component of the extracellular matrix (ECM) in bacterial biofilms. In Candida albicans, there is a scarce knowledge concerning the contribution of extracellular DNA (eDNA) to biofilm matrix and overall structure. This work examined the presence and quantified the amount of eDNA in C. albicans biofilm ECM and the effect of DNase treatment and the addition of exogenous DNA on C. albicans biofilm development as indicators of a role for eDNA in biofilm development. We were able to detect the accumulation of eDNA in biofilm ECM extracted from C. albicans biofilms formed under conditions of flow, although the quantity of eDNA detected differed according to growth conditions, in particular with regards to the medium used to grow the biofilms. Experiments with C. albicans biofilms formed statically using a microtiter plate model indicated that the addition of exogenous DNA (>160 ng/ml) increases biofilm biomass and, conversely, DNase treatment (>0.03 mg/ml) decreases biofilm biomass at later time points of biofilm development. We present evidence for the role of eDNA in C. albicans biofilm structure and formation, consistent with eDNA being a key element of the ECM in mature C. albicans biofilms and playing a predominant role in biofilm structural integrity and maintenance.; National Institute of Dental & Craniofacial Research; Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/28222/2006; National Institute of Allergy and Infectious Diseases

Insights into Candida world : the extracellular milieu

Martins, Margarida; Henriques, Mariana; Oliveira, Rosário
Fonte: Universidade do Minho. Escola de Engenharia Publicador: Universidade do Minho. Escola de Engenharia
Tipo: Conferência ou Objeto de Conferência
Publicado em /10/2010 ENG
Relevância na Pesquisa
56.02%
Over the last years Candida species, including Candida albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida parapsilosis, and Candida tropicalis, have emerged as significant pathogens. This work aimed at bringing insights into Candida species world by the analyses of compounds released into the extracellular medium namely extracellular DNA (eDNA) and alcohol compounds. Concerning eDNA, our results present evidence that this is a key element of the C. albicans biofilm extracellular matrix, contributing to biofilm integrity and antifungal resistance. With respect to extracellular alcohols, the results presented herein show that Candida species secrete a cohort of alcohols that are able to regulate their virulence traits (in vitro and in vivo). Taken together, these studies represent an important contribution to our understanding of the composition of the extracellular milieu of Candida species and its relationship with the regulation of Candida biology, opening the possibility of the development of new treatment and/ or diagnostic strategies to combat candidiasis.

Turnover of Extracellular DNA in Eutrophic and Oligotrophic Freshwater Environments of Southwest Florida

Paul, John H.; Jeffrey, Wade H.; David, Andrew W.; DeFlaun, Mary F.; Cazares, Lisa H.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1989 EN
Relevância na Pesquisa
46.08%
The turnover of extracellular DNA was investigated in oligotrophic springs of the Crystal River and the eutrophic Medard Reservoir of southwest Florida. The Medard Reservoir possessed large populations of bacterioplankton and phytoplankton (6.8 × 109 cells per liter and 28.6 μg of chlorophyll a per liter, respectively), while the Crystal River springs only contained a fraction of the microbial biomass found in the Medard Reservoir. Although dissolved DNA values were greater in the Medard Reservoir, higher rates of DNA removal resulted in similar extracellular DNA turnover times in both environments (9.62 ± 3.6 h in the Crystal River and 10.5 ± 2.1 h in the Medard Reservoir). These results indicate that regardless of trophic status or microbial standing stock, extracellular DNA turns over rapidly in subtropical planktonic freshwater environments. Therefore, recombinant DNA sequences from released genetically engineered microorganisms might not be expected to survive for long periods of time in freshwater planktonic environments.

Extracellular DNA in Single- and Multiple-Species Unsaturated Biofilms

Steinberger, R. E.; Holden, P. A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2005 EN
Relevância na Pesquisa
46.1%
The extracellular polymeric substances (EPS) of bacterial biofilms form a hydrated barrier between cells and their external environment. Better characterization of EPS could be useful in understanding biofilm physiology. The EPS are chemically complex, changing with both bacterial strain and culture conditions. Previously, we reported that Pseudomonas aeruginosa unsaturated biofilm EPS contains large amounts of extracellular DNA (eDNA) (R. E. Steinberger, A. R. Allen, H. G. Hansma, and P. A. Holden, Microb. Ecol. 43:416-423, 2002). Here, we investigated the compositional similarity of eDNA to cellular DNA, the relative quantity of eDNA, and the terminal restriction fragment length polymorphism (TRFLP) community profile of eDNA in multiple-species biofilms. By randomly amplified polymorphic DNA analysis, cellular DNA and eDNA appear identical for P. aeruginosa biofilms. Significantly more eDNA was produced in P. aeruginosa and Pseudomonas putida biofilms than in Rhodococcus erythropolis or Variovorax paradoxus biofilms. While the amount of eDNA in dual-species biofilms was of the same order of magnitude as that of of single-species biofilms, the amounts were not predictable from single-strain measurements. By the Shannon diversity index and principle components analysis of TRFLP profiles generated from 16S rRNA genes...

The role of macrophages in the in vitro generation of extracellular DNA from apoptotic and necrotic cells

Choi, Jin-Jung; Reich, Charles F; Pisetsky, David S
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /05/2005 EN
Relevância na Pesquisa
46.08%
Cell death is a ubiquitous process that occurs by apoptosis or necrosis depending on the triggering event. While apoptotic and necrotic cells differ biochemically, both are cleared by macrophages for elimination. The process is very efficient, although DNA can appear in the blood in various clinical conditions associated with cell death. To define the role of macrophages in the generation of extracellular DNA, in vitro experiments were performed, assessing the release of DNA into the media of apoptotic or necrotic Jurkat cells cultured with RAW264.7 or J774 macrophage cell lines. DNA was measured by a fluorimetric assay using the dye PicoGreen. In these experiments, while necrotic cells alone did not release DNA, in the presence of macrophages, significant amounts of DNA appeared in the medium. This DNA contained sequences from the Jurkat cells and had reduced molecular weight in comparison to cellular DNA. Furthermore, coculture of macrophages with enucleated necrotic Jurkat cells did not release DNA, suggesting that the DNA came from the dead cell. In contrast, Jurkat cells made apoptotic by treatment with either staurosporine or etoposide spontaneously released DNA, while coculture with macrophages caused a decrease in the DNA released. With apoptotic cells...

Extracellular DNA Chelates Cations and Induces Antibiotic Resistance in Pseudomonas aeruginosa Biofilms

Mulcahy, Heidi; Charron-Mazenod, Laetitia; Lewenza, Shawn
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.16%
Biofilms are surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, bacterial polysaccharides and proteins, which are up to 1000-fold more antibiotic resistant than planktonic cultures. To date, extracellular DNA has been shown to function as a structural support to maintain Pseudomonas aeruginosa biofilm architecture. Here we show that DNA is a multifaceted component of P. aeruginosa biofilms. At physiologically relevant concentrations, extracellular DNA has antimicrobial activity, causing cell lysis by chelating cations that stabilize lipopolysaccharide (LPS) and the outer membrane (OM). DNA-mediated killing occurred within minutes, as a result of perturbation of both the outer and inner membrane (IM) and the release of cytoplasmic contents, including genomic DNA. Sub-inhibitory concentrations of DNA created a cation-limited environment that resulted in induction of the PhoPQ- and PmrAB-regulated cationic antimicrobial peptide resistance operon PA3552–PA3559 in P. aeruginosa. Furthermore, DNA-induced expression of this operon resulted in up to 2560-fold increased resistance to cationic antimicrobial peptides and 640-fold increased resistance to aminoglycosides, but had no effect on β-lactam and fluoroquinolone resistance. Thus...

DNA as an Adhesin: Bacillus cereus Requires Extracellular DNA To Form Biofilms▿ †

Vilain, Sébastien; Pretorius, Jakobus M.; Theron, Jacques; Brözel, Volker S.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.09%
The soil saprophyte Bacillus cereus forms biofilms at solid-liquid interfaces. The composition of the extracellular polymeric matrix is not known, but biofilms of other bacteria are encased in polysaccharides, protein, and also extracellular DNA (eDNA). A Tn917 screen for strains impaired in biofilm formation at a solid-liquid interface yielded several mutants. Three mutants deficient in the purine biosynthesis genes purA, purC, and purL were biofilm impaired, but they grew planktonically like the wild type in Luria-Bertani broth. Biofilm populations had higher purA, purC, and purL transcript ratios than planktonic cultures, as measured by real-time PCR. Laser scanning confocal microscopy (LSCM) of BacLight-stained samples indicated that there were nucleic acids in the cell-associated matrix. This eDNA could be mobilized off the biofilm into an agarose gel matrix through electrophoresis, and it was a substrate for DNase. Glass surfaces exposed to exponentially growing populations acquired a DNA-containing conditioning film, as indicated by LSCM. Planktonic exponential-phase cells released DNA into an agarose gel matrix through electrophoresis, while stationary-phase populations did not do this. DNase treatment of planktonic exponential-phase populations rendered cells more susceptible than control populations to the DNA-interacting antibiotic actinomycin D. Exponential-phase purA cells did not contain detectable eDNA...

Evaluation of Different Methods for Extracting Extracellular DNA from the Biofilm Matrix▿

Wu, Jianfeng; Xi, Chuanwu
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.11%
The occurrence of high concentrations of extracellular DNA (eDNA) in the extracellular matrices of biofilms plays an important role in biofilm formation and development and possibly in horizontal gene transfer through natural transformation. Studies have been conducted to characterize the nature of eDNA and its potential function in biofilm development, but it is difficult to extract eDNA from the extracellular matrices of biofilms without any contamination from genomic DNA released by cell lysis during the extraction process. In this report, we compared several different extraction methods in order to obtain highly pure eDNA from different biofilm samples. After different extraction methods were explored, it was concluded that using chemical treatment or enzymatic treatment of biofilm samples may obtain larger amounts of eDNA than using the simple filtration method. There was no detectable cell lysis when the enzymatic treatment methods were used, but substantial cell lysis was observed when the chemical treatment methods were used. These data suggest that eDNA may bind to other extracellular polymers in the biofilm matrix and that enzymatic treatment methods are effective and favorable for extracting eDNA from biofilm samples. Moreover...

Extracellular nucleases and extracellular DNA play important roles in Vibrio cholerae biofilm formation

Seper, Andrea; Fengler, Vera H I; Roier, Sandro; Wolinski, Heimo; Kohlwein, Sepp D; Bishop, Anne L; Camilli, Andrew; Reidl, Joachim; Schild, Stefan
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.09%
Biofilms are a preferred mode of survival for many microorganisms including Vibrio cholerae, the causative agent of the severe secretory diarrhoeal disease cholera. The ability of the facultative human pathogen V. cholerae to form biofilms is a key factor for persistence in aquatic ecosystems and biofilms act as a source for new outbreaks. Thus, a better understanding of biofilm formation and transmission of V. cholerae is an important target to control the disease. So far the Vibrio exopolysaccharide was the only known constituent of the biofilm matrix. In this study we identify and characterize extracellular DNA as a component of the Vibrio biofilm matrix. Furthermore, we show that extracellular DNA is modulated and controlled by the two extracellular nucleases Dns and Xds. Our results indicate that extracellular DNA and the extracellular nucleases are involved in diverse processes including the development of a typical biofilm architecture, nutrient acquisition, detachment from biofilms and the colonization fitness of biofilm clumps after ingestion by the host. This study provides new insights into biofilm development and transmission of biofilm-derived V. cholerae.

Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

Chiang, Wen-Chi; Nilsson, Martin; Jensen, Peter Østrup; Høiby, Niels; Nielsen, Thomas E.; Givskov, Michael; Tolker-Nielsen, Tim
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/2013 EN
Relevância na Pesquisa
46.17%
Within recent years, it has been established that extracellular DNA is a key constituent of the matrix of microbial biofilms. In addition, it has recently been demonstrated that DNA binds positively charged antimicrobials such as aminoglycosides and antimicrobial peptides. In the present study, we provide evidence that extracellular DNA shields against aminoglycosides in Pseudomonas aeruginosa biofilms. We show that exogenously supplemented DNA integrates into P. aeruginosa biofilms and increases their tolerance toward aminoglycosides. We provide evidence that biofilms formed by a DNA release-deficient P. aeruginosa quorum-sensing mutant are more susceptible to aminoglycoside treatment than wild-type biofilms but become rescued from the detrimental action of aminoglycosides upon supplementation with exogenous DNA. Furthermore, we demonstrate that exposure to lysed polymorphonuclear leukocytes, which are thought to be a source of extracellular DNA at sites of infections, increases the tolerance of P. aeruginosa biofilms toward aminoglycosides. Although biofilm-associated aminoglycoside tolerance recently has been linked to extracellular DNA-mediated activation of the pmr genes, we demonstrate that the aminoglycoside tolerance mediated by the presence of extracellular DNA is not caused by activation of the pmr genes in our P. aeruginosa biofilms but rather by a protective shield effect of the extracellular DNA.

Competence-Independent Activity of Pneumococcal Enda Mediates Degradation of Extracellular DNA and Nets and Is Important for Virulence

Zhu, Luchang; Kuang, Zhizhou; Wilson, Brenda A.; Lau, Gee W.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/07/2013 EN
Relevância na Pesquisa
46.09%
Membrane surface localized endonuclease EndA of the pulmonary pathogen Streptococcus pneumoniae (pneumococcus) is required for both genetic transformation and virulence. Pneumococcus expresses EndA during growth. However, it has been reported that EndA has no access to external DNA when pneumococcal cells are not competent for genetic transformation, and thus, unable to degrade extracellular DNA. Here, by using both biochemical and genetic methods, we demonstrate the existence of EndA-mediated nucleolytic activity independent of the competence state of pneumococcal cells. Pneumococcal mutants that are genetically deficient in competence development and genetic transformation have extracellular nuclease activity comparable to their parental wild type, including their ability to degrade neutrophil extracellular traps (NETs). The autolysis deficient ΔlytA mutant and its isogenic choline-treated parental wild-type strain D39 degrade extracellular DNA readily, suggesting that partial cell autolysis is not required for DNA degradation. We show that EndA molecules are secreted into the culture medium during the growth of pneumococcal cells, and contribute substantially to competence-independent nucleolytic activity. The competence-independent activity of EndA is responsible for the rapid degradation of DNA and NETs...

Extracellular DNA metabolism in Haloferax volcanii

Chimileski, Scott; Dolas, Kunal; Naor, Adit; Gophna, Uri; Papke, R. Thane
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 20/02/2014 EN
Relevância na Pesquisa
46.19%
Extracellular DNA is found in all environments and is a dynamic component of the microbial ecosystem. Microbial cells produce and interact with extracellular DNA through many endogenous mechanisms. Extracellular DNA is processed and internalized for use as genetic information and as a major source of macronutrients, and plays several key roles within prokaryotic biofilms. Hypersaline sites contain some of the highest extracellular DNA concentrations measured in nature–a potential rich source of carbon, nitrogen, and phosphorus for halophilic microorganisms. We conducted DNA growth studies for the halophilic archaeon Haloferax volcanii DS2 and show that this model Halobacteriales strain is capable of using exogenous double-stranded DNA as a nutrient. Further experiments with varying medium composition, DNA concentration, and DNA types revealed that DNA is utilized primarily as a phosphorus source, that growth on DNA is concentration-dependent, and that DNA isolated from different sources is metabolized selectively, with a bias against highly divergent methylated DNA. Additionally, fluorescence microscopy showed that labeled DNA co-localized with H. volcanii cells. The gene Hvo_1477 was also identified using a comparative genomic approach as a factor likely to be involved in DNA processing at the cell surface...

RELEASE OF CYSTIC FIBROSIS AIRWAY INFLAMMATORY MARKERS FROM PSEUDOMONAS AERUGINOSA-STIMULATED HUMAN NEUTROPHILS INVOLVES NADPH OXIDASE-DEPENDENT EXTRACELLULAR DNA TRAP FORMATION

Yoo, Dae-goon; Winn, Matthew; Pang, Lan; Moskowitz, Samuel M.; Malech, Harry L.; Leto, Thomas L.; Rada, Balázs
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.09%
Cystic fibrosis (CF) airways are characterized by bacterial infections, excess mucus production and robust neutrophil recruitment. The main CF airway pathogen is Pseudomonas aeruginosa. Neutrophils are not capable of clearing the infection. Neutrophil primary granule components, myeloperoxidase (MPO) and human neutrophil elastase (HNE), are inflammatory markers in CF airways, and their elevated levels are associated with poor lung function. Identifying the mechanism of MPO and HNE release from neutrophils is of high clinical relevance for CF. Here we show that human neutrophils release large amounts of neutrophil extracellular traps (NETs) in the presence of Pseudomonas aeruginosa. Bacteria are entangled in NETs and co-localize with extracellular DNA. MPO, HNE and citrullinated histone H4 are all associated with DNA in Pseudomonas-triggered NETs. Both, laboratory standard strains and CF isolates of Pseudomonas aeruginosa induce DNA, MPO and HNE release from human neutrophils. The increase in peroxidase activity of neutrophil supernatants after Pseudomonas exposure indicates that enzymatically active MPO is released. Pseudomonas aeruginosa induces a robust respiratory burst in neutrophils that is required for extracellular DNA release. Inhibition of the cytoskeleton prevents Pseudomonas-initiated superoxide production and DNA release. NADPH oxidase inhibition suppresses Pseudomonas-induced release of active MPO and HNE. Blocking MEK/ERK signaling results in only minimal inhibition of DNA release induced by Pseudomonas. Our data describe in vitro details of DNA...

Phenazine virulence factor binding to extracellular DNA is important for Pseudomonas aeruginosa biofilm formation

Das, Theerthankar; Kutty, Samuel K.; Tavallaie, Roya; Ibugo, Amaye I.; Panchompoo, Janjira; Sehar, Shama; Aldous, Leigh; Yeung, Amanda W. S.; Thomas, Shane R.; Kumar, Naresh; Gooding, J. Justin; Manefield, Mike
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 11/02/2015 EN
Relevância na Pesquisa
46.13%
Bacterial resistance to conventional antibiotics necessitates the identification of novel leads for infection control. Interference with extracellular phenomena, such as quorum sensing, extracellular DNA integrity and redox active metabolite release, represents a new frontier to control human pathogens such as Pseudomonas aeruginosa and hence reduce mortality. Here we reveal that the extracellular redox active virulence factor pyocyanin produced by P. aeruginosa binds directly to the deoxyribose-phosphate backbone of DNA and intercalates with DNA nitrogenous base pair regions. Binding results in local perturbations of the DNA double helix structure and enhanced electron transfer along the nucleic acid polymer. Pyocyanin binding to DNA also increases DNA solution viscosity. In contrast, antioxidants interacting with DNA and pyocyanin decrease DNA solution viscosity. Biofilms deficient in pyocyanin production and biofilms lacking extracellular DNA show similar architecture indicating the interaction is important in P. aeruginosa biofilm formation.

Extracellular DNA can preserve the genetic signatures of present and past viral infection events in deep hypersaline anoxic basins

Corinaldesi, C.; Tangherlini, M.; Luna, G. M.; Dell'Anno, A.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 07/04/2014 EN
Relevância na Pesquisa
46.16%
Deep hypersaline anoxic basins (DHABs) of the Mediterranean Sea are among the most extreme ecosystems on Earth and host abundant, active and diversified prokaryotic assemblages. However, factors influencing biodiversity and ecosystem functioning are still largely unknown. We investigated, for the first time, the impact of viruses on the prokaryotic assemblages and dynamics of extracellular DNA pool in the sediments of La Medee, the largest DHAB found on Earth. We also compared, in La Medee and L'Atalante sediments, the diversity of prokaryotic 16S rDNA sequences contained in the extracellular DNA released by virus-induced prokaryotic mortality. We found that DHAB sediments are hot-spots of viral infections, which largely contribute to the release of high amounts of extracellular DNA. DNase activities in DHAB sediments were much higher than other extracellular enzymatic activities, suggesting that extracellular DNA released from killed prokaryotes can be the most suitable trophic resource for benthic prokaryotes. Preserved extracellular DNA pools, which contained novel and diversified gene sequences, were very similar between the DHABs but dissimilar from the respective microbial DNA pools. We conclude that the strong viral impact in DHAB sediments influences the genetic composition of extracellular DNA...

Reconocimiento del ADN bacteriano extracelular por neutrófilos humanos: su impacto en la respuesta a biofilms; Extracellular bacterial DNA recognition by human neutrophils: it´s impact on the response to biofilms

Fuxman Bass, Juan Ignacio
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2010 SPA
Relevância na Pesquisa
46.11%
Previamente demostramos que el ADN bacteriano extracelular activa a los neutrófilos a través de un mecanismo diferente al canónico CpG-dependiente. El ADN extracelular es un componente central en la formación y estructura de los biofilms bacterianos, comunidades responsables de más del 60% de las infecciones ocasionadas por estos microorganismos. La presente tesis tuvo como objetivos centrales determinar el impacto del ADN de la matriz de los biofilms en la activación de los neutrófilos humanos y la identificaron del receptor involucrado en el reconocimiento de ADN. Los estudios realizados indicaron que la degradación con DNAsa I del ADN de la matriz extracelular de los biofilms de P. aeruginosa redujo marcadamente su capacidad de inducir la activación de los neutrófilos, determinada en función de su habilidad para producir citoquinas proinflamatorias, incrementar marcadores de activación fisiológicamente relevantes, de mediar la fagocitosis y de liberar trampas extracelulares de los neutrófilos (NET). La aplicación de técnicas de MALDI-TOF nos permitió identificar, en el neutrófilo, 16 proteínas con capacidad de unir ADN bacteriano. A pesar de que ninguna de ellas resultó ser el receptor de la superficie celular para ADN...