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Sample records for active bacterial core

  1. Twenty Years of Active Bacterial Core Surveillance

    PubMed Central

    Schaffner, William; Farley, Monica M.; Lynfield, Ruth; Bennett, Nancy M.; Reingold, Arthur; Thomas, Ann; Harrison, Lee H.; Nichols, Megin; Petit, Susan; Miller, Lisa; Moore, Matthew R.; Schrag, Stephanie J.; Lessa, Fernanda C.; Skoff, Tami H.; MacNeil, Jessica R.; Briere, Elizabeth C.; Weston, Emily J.; Van Beneden, Chris

    2015-01-01

    Active Bacterial Core surveillance (ABCs) was established in 1995 as part of the Centers for Disease Control and Prevention Emerging Infections Program (EIP) network to assess the extent of invasive bacterial infections of public health importance. ABCs is distinctive among surveillance systems because of its large, population-based, geographically diverse catchment area; active laboratory-based identification of cases to ensure complete case capture; detailed collection of epidemiologic information paired with laboratory isolates; infrastructure that allows for more in-depth investigations; and sustained commitment of public health, academic, and clinical partners to maintain the system. ABCs has directly affected public health policies and practices through the development and evaluation of vaccines and other prevention strategies, the monitoring of antimicrobial drug resistance, and the response to public health emergencies and other emerging infections. PMID:26292067

  2. Core Principles of Bacterial Autoinducer Systems

    PubMed Central

    2015-01-01

    SUMMARY Autoinduction (AI), the response to self-produced chemical signals, is widespread in the bacterial world. This process controls vastly different target functions, such as luminescence, nutrient acquisition, and biofilm formation, in different ways and integrates additional environmental and physiological cues. This diversity raises questions about unifying principles that underlie all AI systems. Here, we suggest that such core principles exist. We argue that the general purpose of AI systems is the homeostatic control of costly cooperative behaviors, including, but not limited to, secreted public goods. First, costly behaviors require preassessment of their efficiency by cheaper AI signals, which we encapsulate in a hybrid “push-pull” model. The “push” factors cell density, diffusion, and spatial clustering determine when a behavior becomes effective. The relative importance of each factor depends on each species' individual ecological context and life history. In turn, “pull” factors, often stress cues that reduce the activation threshold, determine the cellular demand for the target behavior. Second, control is homeostatic because AI systems, either themselves or through accessory mechanisms, not only initiate but also maintain the efficiency of target behaviors. Third, AI-controlled behaviors, even seemingly noncooperative ones, are generally cooperative in nature, when interpreted in the appropriate ecological context. The escape of individual cells from biofilms, for example, may be viewed as an altruistic behavior that increases the fitness of the resident population by reducing starvation stress. The framework proposed here helps appropriately categorize AI-controlled behaviors and allows for a deeper understanding of their ecological and evolutionary functions. PMID:25694124

  3. Antarctic ice core samples: culturable bacterial diversity.

    PubMed

    Shivaji, Sisinthy; Begum, Zareena; Shiva Nageswara Rao, Singireesu Soma; Vishnu Vardhan Reddy, Puram V; Manasa, Poorna; Sailaja, Buddi; Prathiba, Mambatta S; Thamban, Meloth; Krishnan, Kottekkatu P; Singh, Shiv M; Srinivas, Tanuku N R

    2013-01-01

    Culturable bacterial abundance at 11 different depths of a 50.26 m ice core from the Tallaksenvarden Nunatak, Antarctica, varied from 0.02 to 5.8 × 10(3) CFU ml(-1) of the melt water. A total of 138 bacterial strains were recovered from the 11 different depths of the ice core. Based on 16S rRNA gene sequence analyses, the 138 isolates could be categorized into 25 phylotypes belonging to phyla Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. All isolates had 16S rRNA sequences similar to previously determined sequences (97.2-100%). No correlation was observed in the distribution of the isolates at the various depths either at the phylum, genus or species level. The 25 phylotypes varied in growth temperature range, tolerance to NaCl, growth pH range and ability to produce eight different extracellular enzymes at either 4 or 18 °C. Iso-, anteiso-, unsaturated and saturated fatty acids together constituted a significant proportion of the total fatty acid composition. PMID:23041141

  4. Phylogenetic organization of bacterial activity.

    PubMed

    Morrissey, Ember M; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; Hayer, Michaela; McHugh, Theresa A; Marks, Jane C; Price, Lance B; Hungate, Bruce A

    2016-09-01

    Phylogeny is an ecologically meaningful way to classify plants and animals, as closely related taxa frequently have similar ecological characteristics, functional traits and effects on ecosystem processes. For bacteria, however, phylogeny has been argued to be an unreliable indicator of an organism's ecology owing to evolutionary processes more common to microbes such as gene loss and lateral gene transfer, as well as convergent evolution. Here we use advanced stable isotope probing with (13)C and (18)O to show that evolutionary history has ecological significance for in situ bacterial activity. Phylogenetic organization in the activity of bacteria sets the stage for characterizing the functional attributes of bacterial taxonomic groups. Connecting identity with function in this way will allow scientists to begin building a mechanistic understanding of how bacterial community composition regulates critical ecosystem functions. PMID:26943624

  5. Phylogenetic organization of bacterial activity

    PubMed Central

    Morrissey, Ember M; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; Hayer, Michaela; McHugh, Theresa A; Marks, Jane C; Price, Lance B; Hungate, Bruce A

    2016-01-01

    Phylogeny is an ecologically meaningful way to classify plants and animals, as closely related taxa frequently have similar ecological characteristics, functional traits and effects on ecosystem processes. For bacteria, however, phylogeny has been argued to be an unreliable indicator of an organism's ecology owing to evolutionary processes more common to microbes such as gene loss and lateral gene transfer, as well as convergent evolution. Here we use advanced stable isotope probing with 13C and 18O to show that evolutionary history has ecological significance for in situ bacterial activity. Phylogenetic organization in the activity of bacteria sets the stage for characterizing the functional attributes of bacterial taxonomic groups. Connecting identity with function in this way will allow scientists to begin building a mechanistic understanding of how bacterial community composition regulates critical ecosystem functions. PMID:26943624

  6. Determination of the Core of a Minimal Bacterial Gene Set†

    PubMed Central

    Gil, Rosario; Silva, Francisco J.; Peretó, Juli; Moya, Andrés

    2004-01-01

    The availability of a large number of complete genome sequences raises the question of how many genes are essential for cellular life. Trying to reconstruct the core of the protein-coding gene set for a hypothetical minimal bacterial cell, we have performed a computational comparative analysis of eight bacterial genomes. Six of the analyzed genomes are very small due to a dramatic genome size reduction process, while the other two, corresponding to free-living relatives, are larger. The available data from several systematic experimental approaches to define all the essential genes in some completely sequenced bacterial genomes were also considered, and a reconstruction of a minimal metabolic machinery necessary to sustain life was carried out. The proposed minimal genome contains 206 protein-coding genes with all the genetic information necessary for self-maintenance and reproduction in the presence of a full complement of essential nutrients and in the absence of environmental stress. The main features of such a minimal gene set, as well as the metabolic functions that must be present in the hypothetical minimal cell, are discussed. PMID:15353568

  7. Comparative Bacterial Proteomics: Analysis of the Core Genome Concept

    SciTech Connect

    Callister, Stephen J.; McCue, Lee Ann; Turse, Josh E.; Monroe, Matthew E.; Auberry, Kenneth J.; Smith, Richard D.; Adkins, Joshua N.; Lipton, Mary S.

    2008-02-06

    Comparative bacterial genomic studies commonly predict a set of genes indicative of common ancestry. Experimental validation of the existence of this core genome requires extensive measurement and is not typically undertaken. Enabled by an extensive proteome database development over a six year period, we experimentally verified the expression of proteins predicted from genomic ortholog comparisons among 17 environmental and pathogenic bacteria. More exclusive relationships were observed among the expressed protein content of phenotypically related bacteria, which is indicative of the specific lifestyles associated with these organisms. While genomic studies establish relative orthologous relationships among a set of bacteria and propose a set of ancestral genes, our proteomics study establishes expressed lifestyle differences among conserved genes and proposes a set of expressed ancestral traits.

  8. Processing of Activated Core Components

    SciTech Connect

    Friske, A.; Gestermann, G.; Finkbeiner, R.

    2003-02-26

    Used activated components from the core of a NPP like control elements, water channels from a BWR, and others like in-core measurement devices need to be processed into waste forms suitable for interim storage, and for the final waste repository. Processing of the activated materials can be undertaken by underwater cutting and packaging or by cutting and high-pressure compaction in a hot cell. A hot cell is available in Germany as a joint investment between GNS and the Karlsruhe Research Center at the latter's site. Special transport equipment is available to transport the components ''as-is'' to the hot cell. Newly designed underwater processing equipment has been designed, constructed, and operated for the special application of NPP decommissioning. This equipment integrates an underwater cutting device with an 80 ton force underwater in-drum compactor.

  9. Pyrosequencing Reveals a Core Community of Anodic Bacterial Biofilms in Bioelectrochemical Systems from China

    PubMed Central

    Xiao, Yong; Zheng, Yue; Wu, Song; Zhang, En-Hua; Chen, Zheng; Liang, Peng; Huang, Xia; Yang, Zhao-Hui; Ng, I-Son; Chen, Bor-Yann; Zhao, Feng

    2015-01-01

    Bioelectrochemical systems (BESs) are promising technologies for energy and product recovery coupled with wastewater treatment, and the core microbial community in electrochemically active biofilm in BESs remains controversy. In the present study, 7 anodic communities from 6 bioelectrochemical systems in 4 labs in southeast, north and south-central of China are explored by 454 pyrosequencing. A total of 251,225 effective sequences are obtained for 7 electrochemically active biofilm samples at 3% cutoff level. While Alpha-, Beta-, and Gamma-proteobacteria are the most abundant classes (averaging 16.0–17.7%), Bacteroidia and Clostridia are the two sub-dominant and commonly shared classes. Six commonly shared genera i.e., Azospira, Azospirillum, Acinetobacter, Bacteroides, Geobacter, Pseudomonas, and Rhodopseudomonas dominate the electrochemically active communities and are defined as core genera. A total of 25 OTUs with average relative abundance >0.5% were selected and designated as core OTUs, and some species relating to these OTUs have been reported electrochemically active. Furthermore, cyclic voltammetry and chronoamperometry tests show that two strains from Acinetobacter guillouiae and Stappia indica, bacteria relate to two core OTUs, are electrochemically active. Using randomly selected bioelectrochemical systems, the study has presented extremely diverse bacterial communities in anodic biofilms, though, we still can suggest some potentially microbes for investigating the electrochemical mechanisms in bioelectrochemical systems. PMID:26733958

  10. Pyrosequencing Reveals a Core Community of Anodic Bacterial Biofilms in Bioelectrochemical Systems from China.

    PubMed

    Xiao, Yong; Zheng, Yue; Wu, Song; Zhang, En-Hua; Chen, Zheng; Liang, Peng; Huang, Xia; Yang, Zhao-Hui; Ng, I-Son; Chen, Bor-Yann; Zhao, Feng

    2015-01-01

    Bioelectrochemical systems (BESs) are promising technologies for energy and product recovery coupled with wastewater treatment, and the core microbial community in electrochemically active biofilm in BESs remains controversy. In the present study, 7 anodic communities from 6 bioelectrochemical systems in 4 labs in southeast, north and south-central of China are explored by 454 pyrosequencing. A total of 251,225 effective sequences are obtained for 7 electrochemically active biofilm samples at 3% cutoff level. While Alpha-, Beta-, and Gamma-proteobacteria are the most abundant classes (averaging 16.0-17.7%), Bacteroidia and Clostridia are the two sub-dominant and commonly shared classes. Six commonly shared genera i.e., Azospira, Azospirillum, Acinetobacter, Bacteroides, Geobacter, Pseudomonas, and Rhodopseudomonas dominate the electrochemically active communities and are defined as core genera. A total of 25 OTUs with average relative abundance >0.5% were selected and designated as core OTUs, and some species relating to these OTUs have been reported electrochemically active. Furthermore, cyclic voltammetry and chronoamperometry tests show that two strains from Acinetobacter guillouiae and Stappia indica, bacteria relate to two core OTUs, are electrochemically active. Using randomly selected bioelectrochemical systems, the study has presented extremely diverse bacterial communities in anodic biofilms, though, we still can suggest some potentially microbes for investigating the electrochemical mechanisms in bioelectrochemical systems. PMID:26733958

  11. Bacterial RNAs activate innate immunity in Arabidopsis.

    PubMed

    Lee, Boyoung; Park, Yong-Soon; Lee, Soohyun; Song, Geun Cheol; Ryu, Choong-Min

    2016-01-01

    The common molecular patterns of microbes play a critical role in the regulation of plant innate immunity. However, little is known about the role of nucleic acids in this process in plants. We pre-infiltrated Arabidopsis leaves with total RNAs from Pseudomonas syringae pv. tomato DC3000 (Pto DC3000) and subsequently inoculated these plants with the same bacterial cells. Total Pto DC3000 RNAs pre-infiltrated into Arabidopsis leaves elicited plant immune responses against Pto DC3000. However, sheared RNAs and RNase A application failed to induce immunity, suggesting that intact bacterial RNAs function in plant innate immunity. This notion was supported by the positive regulation of superoxide anion levels, callose deposition, two mitogen-activated protein kinases and defense-related genes observed in bacterial RNA-pre-treated leaves. Intriguingly, the Pto DC3000 population was not compromised in known pattern recognition receptor mutants for chitin, flagellin and elongation factor-Tu (EF-Tu). Plant defense-related mutant analyses further revealed that bacterial RNA-elicited innate immunity was normally required for salicylic and jasmonic acid signaling. Notably, among total RNAs, the abundant bacterial RNA species 16S and 23S ribosomal RNAs were the major determinants of this response. Our findings provide evidence that bacterial RNA serves as a microbe-associated molecular pattern in plants. PMID:26499893

  12. Optical fiber sensor having an active core

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1993-01-01

    An optical fiber is provided. The fiber is comprised of an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable a is the radius of the active fiber core and k is defined as 2 pi/lambda wherein lambda is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

  13. Bacterial Heat Shock Protein Activity

    PubMed Central

    Maleki, Farajollah; Khosravi, Afra; Nasser, Ahmad; Taghinejad, Hamid

    2016-01-01

    Bacteria are exposed to different types of stress in their growth conditions. They have developed appropriate responses, modulated by the re-modeling of protein complexes and by phosphorylation dependent signal transduction systems, to adapt and to survive in a variety range of nature. Proteins are essential components for biologic activity in the eukaryotic and prokaryotic cell. Heat Shock Proteins (HSP) have been identified from various organisms and have critical role in cell hemostasis. Chaperone can sense environment and have different potential role in the organism evolution. PMID:27134861

  14. Assessing the complex sponge microbiota: core, variable and species-specific bacterial communities in marine sponges

    PubMed Central

    Schmitt, Susanne; Tsai, Peter; Bell, James; Fromont, Jane; Ilan, Micha; Lindquist, Niels; Perez, Thierry; Rodrigo, Allen; Schupp, Peter J; Vacelet, Jean; Webster, Nicole; Hentschel, Ute; Taylor, Michael W

    2012-01-01

    Marine sponges are well known for their associations with highly diverse, yet very specific and often highly similar microbiota. The aim of this study was to identify potential bacterial sub-populations in relation to sponge phylogeny and sampling sites and to define the core bacterial community. 16S ribosomal RNA gene amplicon pyrosequencing was applied to 32 sponge species from eight locations around the world's oceans, thereby generating 2567 operational taxonomic units (OTUs at the 97% sequence similarity level) in total and up to 364 different OTUs per sponge species. The taxonomic richness detected in this study comprised 25 bacterial phyla with Proteobacteria, Chloroflexi and Poribacteria being most diverse in sponges. Among these phyla were nine candidate phyla, six of them found for the first time in sponges. Similarity comparison of bacterial communities revealed no correlation with host phylogeny but a tropical sub-population in that tropical sponges have more similar bacterial communities to each other than to subtropical sponges. A minimal core bacterial community consisting of very few OTUs (97%, 95% and 90%) was found. These microbes have a global distribution and are probably acquired via environmental transmission. In contrast, a large species-specific bacterial community was detected, which is represented by OTUs present in only a single sponge species. The species-specific bacterial community is probably mainly vertically transmitted. It is proposed that different sponges contain different bacterial species, however, these bacteria are still closely related to each other explaining the observed similarity of bacterial communities in sponges in this and previous studies. This global analysis represents the most comprehensive study of bacterial symbionts in sponges to date and provides novel insights into the complex structure of these unique associations. PMID:21993395

  15. Gamma-irradiated bacterial preparation having anti-tumor activity

    SciTech Connect

    Vass, A.A.; Tyndall, R.L.; Terzaghi-Howe, P.

    1999-11-16

    This application describes a bacterial preparation from Pseudomonas species isolated {number{underscore}sign}15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

  16. Gamma-irradiated bacterial preparation having anti-tumor activity

    DOEpatents

    Vass, Arpad A.; Tyndall, Richard L.; Terzaghi-Howe, Peggy

    1999-01-01

    A bacterial preparation from Pseudomonas species isolated #15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

  17. Defining the estimated core genome of bacterial populations using a Bayesian decision model.

    PubMed

    van Tonder, Andries J; Mistry, Shilan; Bray, James E; Hill, Dorothea M C; Cody, Alison J; Farmer, Chris L; Klugman, Keith P; von Gottberg, Anne; Bentley, Stephen D; Parkhill, Julian; Jolley, Keith A; Maiden, Martin C J; Brueggemann, Angela B

    2014-08-01

    The bacterial core genome is of intense interest and the volume of whole genome sequence data in the public domain available to investigate it has increased dramatically. The aim of our study was to develop a model to estimate the bacterial core genome from next-generation whole genome sequencing data and use this model to identify novel genes associated with important biological functions. Five bacterial datasets were analysed, comprising 2096 genomes in total. We developed a Bayesian decision model to estimate the number of core genes, calculated pairwise evolutionary distances (p-distances) based on nucleotide sequence diversity, and plotted the median p-distance for each core gene relative to its genome location. We designed visually-informative genome diagrams to depict areas of interest in genomes. Case studies demonstrated how the model could identify areas for further study, e.g. 25% of the core genes with higher sequence diversity in the Campylobacter jejuni and Neisseria meningitidis genomes encoded hypothetical proteins. The core gene with the highest p-distance value in C. jejuni was annotated in the reference genome as a putative hydrolase, but further work revealed that it shared sequence homology with beta-lactamase/metallo-beta-lactamases (enzymes that provide resistance to a range of broad-spectrum antibiotics) and thioredoxin reductase genes (which reduce oxidative stress and are essential for DNA replication) in other C. jejuni genomes. Our Bayesian model of estimating the core genome is principled, easy to use and can be applied to large genome datasets. This study also highlighted the lack of knowledge currently available for many core genes in bacterial genomes of significant global public health importance. PMID:25144616

  18. Resonant activation: a strategy against bacterial persistence

    NASA Astrophysics Data System (ADS)

    Fu, Yan; Zhu, Meng; Xing, Jianhua

    2010-03-01

    A bacterial colony may develop a small number of cells genetically identical to, but phenotypically different from, other normally growing bacteria. These so-called persister cells keep themselves in a dormant state and thus are insensitive to antibiotic treatment, resulting in serious problems of drug resistance. In this paper, we proposed a novel strategy to 'kill' persister cells by triggering them to switch, in a fast and synchronized way, into normally growing cells that are susceptible to antibiotics. The strategy is based on resonant activation (RA), a well-studied phenomenon in physics where the internal noise of a system can constructively facilitate fast and synchronized barrier crossings. Through stochastic Gilliespie simulation with a generic toggle switch model, we demonstrated that RA exists in the phenotypic switching of a single bacterium. Further, by coupling single cell level and population level simulations, we showed that with RA, one can greatly reduce the time and total amount of antibiotics needed to sterilize a bacterial population. We suggest that resonant activation is a general phenomenon in phenotypic transition, and can find other applications such as cancer therapy.

  19. Antifungal activity of plant and bacterial ureases.

    PubMed

    Becker-Ritt, A B; Martinelli, A H S; Mitidieri, S; Feder, V; Wassermann, G E; Santi, L; Vainstein, M H; Oliveira, J T A; Fiuza, L M; Pasquali, G; Carlini, C R

    2007-12-01

    Ureases (EC 3.5.1.5) are nickel-dependent metalloenzymes that catalyze the hydrolysis of urea to ammonia and carbon dioxide. Produced by plants, fungi and bacteria, but not by animals, ureases share significant homology and similar mechanisms of catalysis, although differing in quaternary structures. While fungal and plant ureases are homo-oligomeric proteins of 90 kDa subunits, bacterial ureases are multimers of two (e.g. Helicobacter pylori) or three subunit complexes. It has been proposed that in plants these enzymes are involved in nitrogen bioavailability and in protection against pathogens. Previous studies by our group have shown that plant ureases, but not a bacterial (Bacillus pasteurii) urease, display insecticidal activity. Herein we demonstrate that (Glycine max) embryo-specific soybean urease, jackbean (Canavalia ensiformis) major urease and a recombinant H. pylori urease impair growth of selected phytopathogenic fungi at sub-micromolar concentrations. This antifungal property of ureases is not affected by treatment of the proteins with an irreversible inhibitor of the ureolytic activity. Scanning electron microscopy of urease-treated fungi suggests plasmolysis and cell wall injuries. Altogether, our data indicate that ureases probably contribute to the plant arsenal of defense compounds against predators and phytopathogens and that the urease defense mechanism is independent of ammonia release from urea. PMID:17825863

  20. Mining bacterial genomes for novel arylesterase activity

    PubMed Central

    Wang, Lijun; Mavisakalyan, Valentina; Tillier, Elisabeth R. M.; Clark, Greg W.; Savchenko, Alexei V.; Yakunin, Alexander F.; Master, Emma R.

    2010-01-01

    Summary One hundred and seventy‐one genes encoding potential esterases from 11 bacterial genomes were cloned and overexpressed in Escherichia coli; 74 of the clones produced soluble proteins. All 74 soluble proteins were purified and screened for esterase activity; 36 proteins showed carboxyl esterase activity on short‐chain esters, 17 demonstrated arylesterase activity, while 38 proteins did not exhibit any activity towards the test substrates. Esterases from Rhodopseudomonas palustris (RpEST‐1, RpEST‐2 and RpEST‐3), Pseudomonas putida (PpEST‐1, PpEST‐2 and PpEST‐3), Pseudomonas aeruginosa (PaEST‐1) and Streptomyces avermitilis (SavEST‐1) were selected for detailed biochemical characterization. All of the enzymes showed optimal activity at neutral or alkaline pH, and the half‐life of each enzyme at 50°C ranged from < 5 min to over 5 h. PpEST‐3, RpEST‐1 and RpEST‐2 demonstrated the highest specific activity with pNP‐esters; these enzymes were also among the most stable at 50°C and in the presence of detergents, polar and non‐polar organic solvents, and imidazolium ionic liquids. Accordingly, these enzymes are particularly interesting targets for subsequent application trials. Finally, biochemical and bioinformatic analyses were compared to reveal sequence features that could be correlated to enzymes with arylesterase activity, facilitating subsequent searches for new esterases in microbial genome sequences. PMID:21255363

  1. The coral core microbiome identifies rare bacterial taxa as ubiquitous endosymbionts.

    PubMed

    D Ainsworth, Tracy; Krause, Lutz; Bridge, Thomas; Torda, Gergely; Raina, Jean-Baptise; Zakrzewski, Martha; Gates, Ruth D; Padilla-Gamiño, Jacqueline L; Spalding, Heather L; Smith, Celia; Woolsey, Erika S; Bourne, David G; Bongaerts, Pim; Hoegh-Guldberg, Ove; Leggat, William

    2015-10-01

    Despite being one of the simplest metazoans, corals harbor some of the most highly diverse and abundant microbial communities. Differentiating core, symbiotic bacteria from this diverse host-associated consortium is essential for characterizing the functional contributions of bacteria but has not been possible yet. Here we characterize the coral core microbiome and demonstrate clear phylogenetic and functional divisions between the micro-scale, niche habitats within the coral host. In doing so, we discover seven distinct bacterial phylotypes that are universal to the core microbiome of coral species, separated by thousands of kilometres of oceans. The two most abundant phylotypes are co-localized specifically with the corals' endosymbiotic algae and symbiont-containing host cells. These bacterial symbioses likely facilitate the success of the dinoflagellate endosymbiosis with corals in diverse environmental regimes. PMID:25885563

  2. The coral core microbiome identifies rare bacterial taxa as ubiquitous endosymbionts

    PubMed Central

    D Ainsworth, Tracy; Krause, Lutz; Bridge, Thomas; Torda, Gergely; Raina, Jean-Baptise; Zakrzewski, Martha; Gates, Ruth D; Padilla-Gamiño, Jacqueline L; Spalding, Heather L; Smith, Celia; Woolsey, Erika S; Bourne, David G; Bongaerts, Pim; Hoegh-Guldberg, Ove; Leggat, William

    2015-01-01

    Despite being one of the simplest metazoans, corals harbor some of the most highly diverse and abundant microbial communities. Differentiating core, symbiotic bacteria from this diverse host-associated consortium is essential for characterizing the functional contributions of bacteria but has not been possible yet. Here we characterize the coral core microbiome and demonstrate clear phylogenetic and functional divisions between the micro-scale, niche habitats within the coral host. In doing so, we discover seven distinct bacterial phylotypes that are universal to the core microbiome of coral species, separated by thousands of kilometres of oceans. The two most abundant phylotypes are co-localized specifically with the corals' endosymbiotic algae and symbiont-containing host cells. These bacterial symbioses likely facilitate the success of the dinoflagellate endosymbiosis with corals in diverse environmental regimes. PMID:25885563

  3. Determination of bacterial activity by use of an evanescent-wave fiber-optic sensor.

    PubMed

    John, M Shelly; Kishen, Anil; Sing, Lim Chu; Asundi, Anand

    2002-12-01

    A novel technique based on fiber-optic evanescent-wave spectroscopy is proposed for the detection of bacterial activity in human saliva. The sensor determines th e specific concentration of Streptococcus mutans in saliva, which is a major causative factor in dental caries. In this design, one prepares the fiber-optic bacterial sensor by replacing a portion of the cladding region of a multimode fiber with a dye-encapsulated xerogel, using the solgel technique. The exponential decay of the evanescent wave at the core-cladding interface of a multimode fiber is utilized for the determination of bacterial activity in saliva. The acidogenic profile of Streptococcus mutans is estimated by use of evanescent-waveabsorption spectra at various levels of bacterial activity. PMID:12477126

  4. Recognition of Heptoses and the Inner Core of Bacterial Lipopolysaccharides by Surfactant Protein D

    SciTech Connect

    Wang,H.; Head, J.; Kosma, P.; Brade, H.; Muller-Loennies, S.; Sheikh, S.; McDonald, B.; Smith, K.; Cafarella, T.; et al

    2008-01-01

    Lipopolysaccharides (LPS) of Gram-negative bacteria are important mediators of bacterial virulence that can elicit potent endotoxic effects. Surfactant protein D (SP-D) shows specific interactions with LPS, both in vitro and in vivo. These interactions involve binding of the carbohydrate recognition domain (CRD) to LPS oligosaccharides (OS); however, little is known about the mechanisms of LPS recognition. Recombinant neck+CRDs (NCRDs) provide an opportunity to directly correlate binding interactions with a crystallographic analysis of the binding mechanism. In these studies, we examined the interactions of wild-type and mutant trimeric NCRDs with rough LPS (R-LPS). Although rat NCRDs bound more efficiently than human NCRDs to Escherichia coli J-5 LPS, both proteins exhibited efficient binding to solid-phase Rd2-LPS and to Rd2-LPS aggregates presented in the solution phase. Involvement of residues flanking calcium at the sugar binding site was demonstrated by reciprocal exchange of lysine and arginine at position 343 of rat and human CRDs. The lectin activity of hNCRDs was inhibited by specific heptoses, including l-glycero-{alpha}-d-manno-heptose (l, d-heptose), but not by 3-deoxy-{alpha}-d-manno-oct-2-ulosonic acid (Kdo). Crystallographic analysis of the hNCRD demonstrated a novel binding orientation for l, d-heptose, involving the hydroxyl groups of the side chain. Similar binding was observed for a synthetic {alpha}1{yields}3-linked heptose disaccharide corresponding to heptoses I and II of the inner core region in many LPS. 7-O-Carbamoyl-l, d-heptose and d-glycero-{alpha}-d-manno-heptose were bound via ring hydroxyl groups. Interactions with the side chain of inner core heptoses provide a potential mechanism for the recognition of diverse types of LPS by SP-D.

  5. Bacterial community structure in the hyperarid core of the Atacama Desert, Chile

    USGS Publications Warehouse

    Drees, Kevin P.; Neilson, Julia W.; Betancourt, Julio L.; Quade, Jay; Henderson, David A.; Pryor, Barry M.; Maier, Raina M.

    2006-01-01

    Soils from the hyperarid Atacama Desert of northern Chile were sampled along an east-west elevational transect (23.75 to 24.70 degrees S) through the driest sector to compare the relative structure of bacterial communities. Analysis of denaturing gradient gel electrophoresis (DGGE) profiles from each of the samples revealed that microbial communities from the extreme hyperarid core of the desert clustered separately from all of the remaining communities. Bands sequenced from DGGE profiles of two samples taken at a 22-month interval from this core region revealed the presence of similar populations dominated by bacteria from the Gemmatimonadetes and Planctomycetes phyla.

  6. Bacterial Community Structure in the Hyperarid Core of the Atacama Desert, Chile▿

    PubMed Central

    Drees, Kevin P.; Neilson, Julia W.; Betancourt, Julio L.; Quade, Jay; Henderson, David A.; Pryor, Barry M.; Maier, Raina M.

    2006-01-01

    Soils from the hyperarid Atacama Desert of northern Chile were sampled along an east-west elevational transect (23.75 to 24.70°S) through the driest sector to compare the relative structure of bacterial communities. Analysis of denaturing gradient gel electrophoresis (DGGE) profiles from each of the samples revealed that microbial communities from the extreme hyperarid core of the desert clustered separately from all of the remaining communities. Bands sequenced from DGGE profiles of two samples taken at a 22-month interval from this core region revealed the presence of similar populations dominated by bacteria from the Gemmatimonadetes and Planctomycetes phyla. PMID:17028238

  7. Humpback whale populations share a core skin bacterial community: towards a health index for marine mammals?

    PubMed

    Apprill, Amy; Robbins, Jooke; Eren, A Murat; Pack, Adam A; Reveillaud, Julie; Mattila, David; Moore, Michael; Niemeyer, Misty; Moore, Kathleen M T; Mincer, Tracy J

    2014-01-01

    Microbes are now well regarded for their important role in mammalian health. The microbiology of skin--a unique interface between the host and environment--is a major research focus in human health and skin disorders, but is less explored in other mammals. Here, we report on a cross-population study of the skin-associated bacterial community of humpback whales (Megaptera novaeangliae), and examine the potential for a core bacterial community and its variability with host (endogenous) or geographic/environmental (exogenous) specific factors. Skin biopsies or freshly sloughed skin from 56 individuals were sampled from populations in the North Atlantic, North Pacific and South Pacific oceans and bacteria were characterized using 454 pyrosequencing of SSU rRNA genes. Phylogenetic and statistical analyses revealed the ubiquity and abundance of bacteria belonging to the Flavobacteria genus Tenacibaculum and the Gammaproteobacteria genus Psychrobacter across the whale populations. Scanning electron microscopy of skin indicated that microbial cells colonize the skin surface. Despite the ubiquity of Tenacibaculum and Psychrobater spp., the relative composition of the skin-bacterial community differed significantly by geographic area as well as metabolic state of the animals (feeding versus starving during migration and breeding), suggesting that both exogenous and endogenous factors may play a role in influencing the skin-bacteria. Further, characteristics of the skin bacterial community from these free-swimming individuals were assembled and compared to two entangled and three dead individuals, revealing a decrease in the central or core bacterial community members (Tenacibaculum and Psychrobater spp.), as well as the emergence of potential pathogens in the latter cases. This is the first discovery of a cross-population, shared skin bacterial community. This research suggests that the skin bacteria may be connected to humpback health and immunity and could possibly serve

  8. Humpback Whale Populations Share a Core Skin Bacterial Community: Towards a Health Index for Marine Mammals?

    PubMed Central

    Apprill, Amy; Robbins, Jooke; Eren, A. Murat; Pack, Adam A.; Reveillaud, Julie; Mattila, David; Moore, Michael; Niemeyer, Misty; Moore, Kathleen M. T.; Mincer, Tracy J.

    2014-01-01

    Microbes are now well regarded for their important role in mammalian health. The microbiology of skin – a unique interface between the host and environment - is a major research focus in human health and skin disorders, but is less explored in other mammals. Here, we report on a cross-population study of the skin-associated bacterial community of humpback whales (Megaptera novaeangliae), and examine the potential for a core bacterial community and its variability with host (endogenous) or geographic/environmental (exogenous) specific factors. Skin biopsies or freshly sloughed skin from 56 individuals were sampled from populations in the North Atlantic, North Pacific and South Pacific oceans and bacteria were characterized using 454 pyrosequencing of SSU rRNA genes. Phylogenetic and statistical analyses revealed the ubiquity and abundance of bacteria belonging to the Flavobacteria genus Tenacibaculum and the Gammaproteobacteria genus Psychrobacter across the whale populations. Scanning electron microscopy of skin indicated that microbial cells colonize the skin surface. Despite the ubiquity of Tenacibaculum and Psychrobater spp., the relative composition of the skin-bacterial community differed significantly by geographic area as well as metabolic state of the animals (feeding versus starving during migration and breeding), suggesting that both exogenous and endogenous factors may play a role in influencing the skin-bacteria. Further, characteristics of the skin bacterial community from these free-swimming individuals were assembled and compared to two entangled and three dead individuals, revealing a decrease in the central or core bacterial community members (Tenacibaculum and Psychrobater spp.), as well as the emergence of potential pathogens in the latter cases. This is the first discovery of a cross-population, shared skin bacterial community. This research suggests that the skin bacteria may be connected to humpback health and immunity and could possibly

  9. Spatial Changes in the Bacterial Community Structure along a Vertical Oxygen Gradient in Flooded Paddy Soil Cores

    PubMed Central

    Lüdemann, Heiner; Arth, Inko; Liesack, Werner

    2000-01-01

    Molecular ecology techniques were applied to assess changes in the bacterial community structure along a vertical oxygen gradient in flooded paddy soil cores. Microsensor measurements showed that oxygen was depleted from 140 μM at the floodwater/soil interface to nondetectable amounts at a depth of approximately 2.0 mm and below. Bacterial 16S rRNA gene (rDNA)-based community fingerprint patterns were obtained from 200-μm-thick soil slices of both the oxic and anoxic zones by using the T-RFLP (terminal restriction fragment length polymorphism) technique. The fingerprints revealed a tremendous shift in the community patterns in correlation to the oxygen depletion measured with depth. 16S rDNA clone sequences recovered from the oxic or anoxic zone directly corresponded to those terminal restriction fragments which were highly characteristic of the respective zone. Comparative sequence analysis of these clones identified members of the α and β subclasses of Proteobacteria as the abundant populations in the oxic zone. In contrast, members of clostridial cluster I were determined to be the predominant bacterial group in the oxygen-depleted soil. The extraction of total RNA followed by reverse transcription-PCR of the bacterial 16S rRNA and T-RFLP analysis resulted for both oxic and anoxic zones of flooded soil cores in community fingerprint patterns similar to those obtained by the rDNA-based analysis. This finding suggests that the microbial groups detected on the rDNA level are the metabolically active populations within the oxic and anoxic soil slices examined. PMID:10653747

  10. Increased dietary zinc oxide changes the bacterial core and enterobacterial composition in the ileum of piglets.

    PubMed

    Vahjen, W; Pieper, R; Zentek, J

    2011-08-01

    This study was conducted to investigate the effects of increased dietary ZnO on the bacterial core and enterobacterial composition in the small intestine of piglets that were fed diets containing a total of 124 or 3,042 mg of Zn per kilogram of diet, respectively. Zinc was supplemented to the basal diet as ZnO. Bacterial 16S rRNA genes of ileal DNA extracts were PCR-amplified with 2 bar-coded primer sets and sequenced by 454 pyrosequencing. The bacterial core species were calculated from the relative abundances of reads present in 5 of 6 samples per group and at a minimum of 5 sequences per sample. The reference database SILVA was used to assign sequence reads at an alignment minimum of 200 bases and 100% identity. Lactic acid bacteria dominated the bacterial core, but showed diverse responses to dietary ZnO. Of the dominant Lactobacillus spp., Lactobacillus reuteri was reduced due to increased dietary ZnO (44.7 vs. 17.9%; P=0.042), but L. amylovorus was not influenced. However, the changes of relative abundances of other lactic acid bacteria were more noteworthy; Weissella cibaria (10.7 vs. 23.0%; P=0.006), W. confusa (10.0 vs. 22.4%; P=0.037), Leuconostoc citreum (6.5 vs. 14.8%; P=0.009), Streptococcus equinus (0.14 vs. 1.0%; P=0.044), and S. lutetiensis (0.01 vs. 0.11%; P=0.016) increased in relative abundance. Nonlactic acid bacteria that were influenced by increased dietary ZnO included the strict anaerobic species, Sarcina ventriculi, which showed a strong numerical decrease in relative abundance (14.6 vs. 5.1%). Species of the Enterobacteriaceae increased their relative abundance, as well as species diversity, in the high dietary ZnO experimental group. Bacterial diversity indices were increased due to increased dietary ZnO (P < 0.05), which was traced back to the increase of sequences from subdominant species. Increased dietary ZnO led to an increase of less prominent species and, thus, had a major impact on the bacterial composition and diversity in

  11. Relative Roles of Deterministic and Stochastic Processes in Driving the Vertical Distribution of Bacterial Communities in a Permafrost Core from the Qinghai-Tibet Plateau, China

    PubMed Central

    Tian, Tian; Li, Dingyao; Cheng, Gang; Mu, Jing; Wu, Qingbai; Niu, Fujun; Stegen, James C.; An, Lizhe; Feng, Huyuan

    2015-01-01

    Understanding the processes that influence the structure of biotic communities is one of the major ecological topics, and both stochastic and deterministic processes are expected to be at work simultaneously in most communities. Here, we investigated the vertical distribution patterns of bacterial communities in a 10-m-long soil core taken within permafrost of the Qinghai-Tibet Plateau. To get a better understanding of the forces that govern these patterns, we examined the diversity and structure of bacterial communities, and the change in community composition along the vertical distance (spatial turnover) from both taxonomic and phylogenetic perspectives. Measures of taxonomic and phylogenetic beta diversity revealed that bacterial community composition changed continuously along the soil core, and showed a vertical distance-decay relationship. Multiple stepwise regression analysis suggested that bacterial alpha diversity and phylogenetic structure were strongly correlated with soil conductivity and pH but weakly correlated with depth. There was evidence that deterministic and stochastic processes collectively drived bacterial vertically-structured pattern. Bacterial communities in five soil horizons (two originated from the active layer and three from permafrost) of the permafrost core were phylogenetically random, indicator of stochastic processes. However, we found a stronger effect of deterministic processes related to soil pH, conductivity, and organic carbon content that were structuring the bacterial communities. We therefore conclude that the vertical distribution of bacterial communities was governed primarily by deterministic ecological selection, although stochastic processes were also at work. Furthermore, the strong impact of environmental conditions (for example, soil physicochemical parameters and seasonal freeze-thaw cycles) on these communities underlines the sensitivity of permafrost microorganisms to climate change and potentially subsequent

  12. Relative Roles of Deterministic and Stochastic Processes in Driving the Vertical Distribution of Bacterial Communities in a Permafrost Core from the Qinghai-Tibet Plateau, China.

    PubMed

    Hu, Weigang; Zhang, Qi; Tian, Tian; Li, Dingyao; Cheng, Gang; Mu, Jing; Wu, Qingbai; Niu, Fujun; Stegen, James C; An, Lizhe; Feng, Huyuan

    2015-01-01

    Understanding the processes that influence the structure of biotic communities is one of the major ecological topics, and both stochastic and deterministic processes are expected to be at work simultaneously in most communities. Here, we investigated the vertical distribution patterns of bacterial communities in a 10-m-long soil core taken within permafrost of the Qinghai-Tibet Plateau. To get a better understanding of the forces that govern these patterns, we examined the diversity and structure of bacterial communities, and the change in community composition along the vertical distance (spatial turnover) from both taxonomic and phylogenetic perspectives. Measures of taxonomic and phylogenetic beta diversity revealed that bacterial community composition changed continuously along the soil core, and showed a vertical distance-decay relationship. Multiple stepwise regression analysis suggested that bacterial alpha diversity and phylogenetic structure were strongly correlated with soil conductivity and pH but weakly correlated with depth. There was evidence that deterministic and stochastic processes collectively drived bacterial vertically-structured pattern. Bacterial communities in five soil horizons (two originated from the active layer and three from permafrost) of the permafrost core were phylogenetically random, indicator of stochastic processes. However, we found a stronger effect of deterministic processes related to soil pH, conductivity, and organic carbon content that were structuring the bacterial communities. We therefore conclude that the vertical distribution of bacterial communities was governed primarily by deterministic ecological selection, although stochastic processes were also at work. Furthermore, the strong impact of environmental conditions (for example, soil physicochemical parameters and seasonal freeze-thaw cycles) on these communities underlines the sensitivity of permafrost microorganisms to climate change and potentially subsequent

  13. Comparison of bacterial communities of conventional and A-stage activated sludge systems

    PubMed Central

    Gonzalez-Martinez, Alejandro; Rodriguez-Sanchez, Alejandro; Lotti, Tommaso; Garcia-Ruiz, Maria-Jesus; Osorio, Francisco; Gonzalez-Lopez, Jesus; van Loosdrecht, Mark C. M.

    2016-01-01

    The bacterial community structure of 10 different wastewater treatment systems and their influents has been investigated through pyrosequencing, yielding a total of 283486 reads. These bioreactors had different technological configurations: conventional activated sludge (CAS) systems and very highly loaded A-stage systems. A-stage processes are proposed as the first step in an energy producing municipal wastewater treatment process. Pyrosequencing analysis indicated that bacterial community structure of all influents was similar. Also the bacterial community of all CAS bioreactors was similar. Bacterial community structure of A-stage bioreactors showed a more case-specific pattern. A core of genera was consistently found for all influents, all CAS bioreactors and all A-stage bioreactors, respectively, showing that different geographical locations in The Netherlands and Spain did not affect the functional bacterial communities in these technologies. The ecological roles of these bacteria were discussed. Influents and A-stage bioreactors shared several core genera, while none of these were shared with CAS bioreactors communities. This difference is thought to reside in the different operational conditions of the two technologies. This study shows that bacterial community structure of CAS and A-stage bioreactors are mostly driven by solids retention time (SRT) and hydraulic retention time (HRT), as suggested by multivariate redundancy analysis. PMID:26728449

  14. Effect of antibiotic use on bacterial flora of tonsil core in patients with recurrent tonsillitis.

    PubMed

    Yildizoglu, Uzeyir; Polat, Bahtiyar; Gumral, Ramazan; Kilic, Abdullah; Tosun, Fuat; Gerek, Mustafa

    2015-06-01

    The aim of this study was to investigate the effects of commonly used antibiotics on bacterial flora of the tonsil core. Patients who underwent tonsillectomy for recurrent chronic tonsillitis were included in the study. Three groups were formed: group 1 was treated for 10 days preoperatively with amoxicillin/clavulanic acid; group 2 was treated for 10 days preoperatively with clarithromycin; and group 3 included patients who underwent tonsillectomy without preoperative antibiotic use. The removed palatine tonsils were sent to our microbiology department in sterile tubes for bacteriological analysis. Seventy-three patients (group 1 = 19, group 2 = 20, group 3 = 34 patients) aged 3-18 years (mean 7 years) were included in the study. At least one bacterium was isolated from all tonsils, except for two cases in group 1; the difference in single bacterial growth among groups was not significant (p = 0.06). On the other hand, the numbers of patients with pathogenic bacterial growth was significantly lower in group 2 (n = 2) compared with group 1 (n = 10) and group 3 (n = 27) (p < 0.001). The bacterium isolated most frequently from the tonsils was Streptococcus viridans. Pseudomonas aeruginosa was the only pathogenic bacterium that grew in all three groups. Clarithromycin was more effective than amoxicillin/clavulanic acid in eradicating pathogenic bacteria in the tonsil core. Pseudomonas aeruginosa might be responsible for resistant or recurrent tonsil infections. To prevent endocarditis, antibiotic prophylaxis toward S. viridians, which is the most prevalent bacterium in the tonsil core, should be kept in mind for patients with heart valve damage. PMID:25510984

  15. Bacterial recognition pathways that lead to inflammasome activation

    PubMed Central

    Storek, Kelly M; Monack, Denise M

    2015-01-01

    Inflammasomes are multi-protein signaling platforms that upon activation trigger the maturation of the pro-inflammatory cytokines, interleukin-1β (IL-1β) and IL-18, and cell death. Inflammasome sensors detect microbial and host-derived molecules. Here, we review the mechanisms of inflammasome activation triggered by bacterial infection, primarily focusing on two model intracellular bacterial pathogens, Francisella novicida and Salmonella typhimurium. We discuss the complex relationship between bacterial recognition through direct and indirect detection by inflammasome sensors. We highlight regulation mechanisms that potentiate or limit inflammasome activation. We discuss the importance of caspase-1 and caspase-11 in host defense, and we examine the downstream consequences of inflammasome activation within the context of bacterial infections. PMID:25879288

  16. Bacterial study of Vostok drilling fluid: the tool to make ice core finding confident

    NASA Astrophysics Data System (ADS)

    Alekhina, I. A.; Petit, J. R.; Lukin, V. V.; Bulat, S. A.

    2003-04-01

    Decontamination of Vostok ice core is a critical issue in molecular biology studies. Core surface contains a film of hardly removable 'dirty' drilling fluid representing a mixture of polyhydrocarbons (PHC) including polyaromatic hydrocarbons (PAH) and freon. To make ice microbial finding more confident the original Vostok drilling fluid sampled from different depths (110m - 3600m) was analyzed for bacterial content by ribosomal DNA sequencing. Total, 33 clones of 16S ribosomal DNA were recovered from four samples of drilling fluid at 110, 2750, 3400, and 3600m leading to identification of 8 bacterial species. No overlapping was observed even for neighboring samples (3400m and 3600m). At present four major bacteria with the titer more than 103-104 cells per ml (as estimated from PCR results) are identified. Among them we found: unknown representative of Desulfobacteraceae which are able to oxidize sulphates and degrade benzenes (110m); PAH-degrading alpha-proteobacterium Sphingomonas natatoria (3400m); alpha-proteobacterium representing closely-related group of Sphingomonas sp. (e.g., S. aurantiaca) which are able to degrade PAH as well, and human pathogen closely related to Haloanella gallinarum of CFB group (3600m). Four additional species were revealed as single clones and showed relatedness to human pathogens and saprophytes as well as soil bacteria. These bacteria may represent drilling fluid contaminants introduced during its sampling or DNA extraction procedure. Of four major bacteria revealed, one species, Sphingomonas natatoria, has been met by us in the Vostok core from 3607 m depth (AF532054) whereas another Sphingomonas sp. which we refer to as S. aurantiaca was found in Antarctic microbial endolithic community (AF548567), hydrocarbon-containing soil near Scott Base in Antarctica (AF184221) and even isolated from 3593m Vostok accretion ice (AF324199) and Taylor Dome core (AF395031). The source for major human pathogen-related bacteria is rather uncertain

  17. Independent studies using deep sequencing resolve the same set of core bacterial species dominating gut communities of honey bees.

    PubMed

    Sabree, Zakee L; Hansen, Allison K; Moran, Nancy A

    2012-01-01

    Starting in 2003, numerous studies using culture-independent methodologies to characterize the gut microbiota of honey bees have retrieved a consistent and distinctive set of eight bacterial species, based on near identity of the 16S rRNA gene sequences. A recent study [Mattila HR, Rios D, Walker-Sperling VE, Roeselers G, Newton ILG (2012) Characterization of the active microbiotas associated with honey bees reveals healthier and broader communities when colonies are genetically diverse. PLoS ONE 7(3): e32962], using pyrosequencing of the V1-V2 hypervariable region of the 16S rRNA gene, reported finding entirely novel bacterial species in honey bee guts, and used taxonomic assignments from these reads to predict metabolic activities based on known metabolisms of cultivable species. To better understand this discrepancy, we analyzed the Mattila et al. pyrotag dataset. In contrast to the conclusions of Mattila et al., we found that the large majority of pyrotag sequences belonged to clusters for which representative sequences were identical to sequences from previously identified core species of the bee microbiota. On average, they represent 95% of the bacteria in each worker bee in the Mattila et al. dataset, a slightly lower value than that found in other studies. Some colonies contain small proportions of other bacteria, mostly species of Enterobacteriaceae. Reanalysis of the Mattila et al. dataset also did not support a relationship between abundances of Bifidobacterium and of putative pathogens or a significant difference in gut communities between colonies from queens that were singly or multiply mated. Additionally, consistent with previous studies, the dataset supports the occurrence of considerable strain variation within core species, even within single colonies. The roles of these bacteria within bees, or the implications of the strain variation, are not yet clear. PMID:22829932

  18. Independent Studies Using Deep Sequencing Resolve the Same Set of Core Bacterial Species Dominating Gut Communities of Honey Bees

    PubMed Central

    Sabree, Zakee L.; Hansen, Allison K.; Moran, Nancy A.

    2012-01-01

    Starting in 2003, numerous studies using culture-independent methodologies to characterize the gut microbiota of honey bees have retrieved a consistent and distinctive set of eight bacterial species, based on near identity of the 16S rRNA gene sequences. A recent study [Mattila HR, Rios D, Walker-Sperling VE, Roeselers G, Newton ILG (2012) Characterization of the active microbiotas associated with honey bees reveals healthier and broader communities when colonies are genetically diverse. PLoS ONE 7(3): e32962], using pyrosequencing of the V1–V2 hypervariable region of the 16S rRNA gene, reported finding entirely novel bacterial species in honey bee guts, and used taxonomic assignments from these reads to predict metabolic activities based on known metabolisms of cultivable species. To better understand this discrepancy, we analyzed the Mattila et al. pyrotag dataset. In contrast to the conclusions of Mattila et al., we found that the large majority of pyrotag sequences belonged to clusters for which representative sequences were identical to sequences from previously identified core species of the bee microbiota. On average, they represent 95% of the bacteria in each worker bee in the Mattila et al. dataset, a slightly lower value than that found in other studies. Some colonies contain small proportions of other bacteria, mostly species of Enterobacteriaceae. Reanalysis of the Mattila et al. dataset also did not support a relationship between abundances of Bifidobacterium and of putative pathogens or a significant difference in gut communities between colonies from queens that were singly or multiply mated. Additionally, consistent with previous studies, the dataset supports the occurrence of considerable strain variation within core species, even within single colonies. The roles of these bacteria within bees, or the implications of the strain variation, are not yet clear. PMID:22829932

  19. Conservation and Covariance in Small Bacterial Phosphoglycosyltransferases Identify the Functional Catalytic Core.

    PubMed

    Lukose, Vinita; Luo, Lingqi; Kozakov, Dima; Vajda, Sandor; Allen, Karen N; Imperiali, Barbara

    2015-12-22

    Phosphoglycosyltransferases (PGTs) catalyze the transfer of a C1'-phosphosugar from a soluble sugar nucleotide diphosphate to a polyprenol phosphate. These enzymes act at the membrane interface, forming the first membrane-associated intermediates in the biosynthesis of cell-surface glycans and glycoconjugates, including glycoproteins, glycolipids, and the peptidoglycan in bacteria. PGTs vary greatly in both their membrane topologies and their substrate preferences. PGTs, such as MraY and WecA, are polytopic, while other families of uniquely prokaryotic enzymes have only a single predicted transmembrane helix. PglC, a PGT involved in the biosynthesis of N-linked glycoproteins in the enteropathogen Campylobacter jejuni, is representative of one of the structurally most simple members of the diverse family of small bacterial PGT enzymes. Herein, we apply bioinformatics and covariance-weighted distance constraints in geometry- and homology-based model building, together with mutational analysis, to investigate monotopic PGTs. The pool of 15000 sequences that are analyzed include the PglC-like enzymes, as well as sequences from two other related PGTs that contain a "PglC-like" domain embedded in their larger structures (namely, the bifunctional PglB family, typified by PglB from Neisseria gonorrheae, and WbaP-like enzymes, typified by WbaP from Salmonella enterica). Including these two subfamilies of PGTs in the analysis highlights key residues conserved across all three families of small bacterial PGTs. Mutagenesis analysis of these conserved residues provides further information about the essentiality of many of these residues in catalysis. Construction of a structural model of the cytosolic globular domain utilizing three-dimensional distance constraints, provided by conservation covariance analysis, provides additional insight into the catalytic core of these families of small bacterial PGT enzymes. PMID:26600273

  20. Metal Toxicity Affects Fungal and Bacterial Activities in Soil Differently

    PubMed Central

    Rajapaksha, R. M. C. P.; Tobor-Kapłon, M. A; Bååth, E.

    2004-01-01

    Although the toxic effect of heavy metals on soil microorganism activity is well known, little is known about the effects on different organism groups. The influence of heavy metal addition on total, bacterial, and fungal activities was therefore studied for up to 60 days in a laboratory experiment using forest soil contaminated with different concentrations of Zn or Cu. The effects of the metals differed between the different activity measurements. During the first week after metal addition, the total activity (respiration rate) decreased by 30% at the highest level of contamination and then remained stable during the 60 days of incubation. The bacterial activity (thymidine incorporation rate) decreased during the first days with the level of metal contamination, resulting in a 90% decrease at the highest level of contamination. Bacterial activity then slowly recovered to values similar to those of the control soil. The recovery was faster when soil pH, which had decreased due to metal addition, was restored to control values by liming. Fungal activity (acetate-in-ergosterol incorporation rate) initially increased with the level of metal contamination, being up to 3 and 7 times higher than that in the control samples during the first week at the highest levels of Zn and Cu addition, respectively. The positive effect of metal addition on fungal activity then decreased, but fungal activity was still higher in contaminated than in control soil after 35 days. This is the first direct evidence that fungal and bacterial activities in soil are differently affected by heavy metals. The different responses of bacteria and fungi to heavy metals were reflected in an increase in the relative fungal/bacterial ratio (estimated using phospholipid fatty acid analysis) with increased metal load. PMID:15128558

  1. Metal toxicity affects fungal and bacterial activities in soil differently.

    PubMed

    Rajapaksha, R M C P; Tobor-Kapłon, M A; Bååth, E

    2004-05-01

    Although the toxic effect of heavy metals on soil microorganism activity is well known, little is known about the effects on different organism groups. The influence of heavy metal addition on total, bacterial, and fungal activities was therefore studied for up to 60 days in a laboratory experiment using forest soil contaminated with different concentrations of Zn or Cu. The effects of the metals differed between the different activity measurements. During the first week after metal addition, the total activity (respiration rate) decreased by 30% at the highest level of contamination and then remained stable during the 60 days of incubation. The bacterial activity (thymidine incorporation rate) decreased during the first days with the level of metal contamination, resulting in a 90% decrease at the highest level of contamination. Bacterial activity then slowly recovered to values similar to those of the control soil. The recovery was faster when soil pH, which had decreased due to metal addition, was restored to control values by liming. Fungal activity (acetate-in-ergosterol incorporation rate) initially increased with the level of metal contamination, being up to 3 and 7 times higher than that in the control samples during the first week at the highest levels of Zn and Cu addition, respectively. The positive effect of metal addition on fungal activity then decreased, but fungal activity was still higher in contaminated than in control soil after 35 days. This is the first direct evidence that fungal and bacterial activities in soil are differently affected by heavy metals. The different responses of bacteria and fungi to heavy metals were reflected in an increase in the relative fungal/bacterial ratio (estimated using phospholipid fatty acid analysis) with increased metal load. PMID:15128558

  2. Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells

    PubMed Central

    2010-01-01

    Background In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry. To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process. To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. Results In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared. During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation. During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity. High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. Conclusions The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells. PMID:20831775

  3. Bacterial vectors for active immunotherapy reach clinical and industrial stages

    PubMed Central

    Le Gouëllec, Audrey; Chauchet, Xavier; Polack, Benoit; Buffat, Laurent; Toussaint, Bertrand

    2012-01-01

    Active immunotherapy based on live attenuated bacterial vectors has matured in terms of industrial development and develops through a combination of three phenomena. First, active immunotherapy that stimulates an antigen-specific cytotoxic T-cell immune response has become a reality after several years of work. Second, there is still a need to identify vectors that can deliver antigens to the cytosol of antigen-presenting cells in vivo. Third, the recent progress in the understanding of bacterial lifestyle and in developing genetic engineering tools has enabled the design of bioengineered bugs that are capable of delivering antigens. Here, we review the mechanisms by which clinical bacterial vectors deliver antigens into the cytosol of antigen-presenting cells and summarize the development strategy of the three identified firms in this field. PMID:22894945

  4. A study on the vertical profile of bacterial DNA structure in the Puruogangri (Tibetan Plateau) ice core using denaturing gradient gel electrophoresis

    NASA Astrophysics Data System (ADS)

    Zhang, Xinfang; Yao, Tandong; An, Lizhe; Tian, Lide; Xu, Shijian

    The bacterial DNA structures at different depths in the Puruogangri (Tibetan Plateau) ice core (83.45 m) were investigated by the denaturing gradient gel electrophoresis (DGGE) DNA fingerprinting technique. DGGE profiles indicated that the bacterial species diversity in glacial ice is high, and indigenous species represented by common bands in all samples may grow on the glacial surface. Bacterial diversity, as estimated by Shannon indices (mean 2.91; SD 0.25; n = 13), was comparable to that of soil habitats and had a positive correlation with Ca2+ concentration (R = 0.71; P < 0.01), a good proxy of dust. This suggested that the soil ecosystem was the main source of bacteria in this glacier. The low similarity indices (0-43%) were found between the ice-core samples, which corresponded to the episodic deposition under defined climatic conditions and low activity of microorganisms in glacial ice. The profiles of bacterial species composition in glacial ice may be a bioindicator of climatic changes or dating.

  5. Collective chemotaxis and segregation of active bacterial colonies.

    PubMed

    Ben Amar, M

    2016-01-01

    Still recently, bacterial fluid suspensions have motivated a lot of works, both experimental and theoretical, with the objective to understand their collective dynamics from universal and simple rules. Since some species are active, most of these works concern the strong interactions that these bacteria exert on a forced flow leading to instabilities, chaos and turbulence. Here, we investigate the self-organization of expanding bacterial colonies under chemotaxis, proliferation and eventually active-reaction. We propose a simple model to understand and quantify the physical properties of these living organisms which either give cohesion or on the contrary dispersion to the colony. Taking into account the diffusion and capture of morphogens complicates the model since it induces a bacterial density gradient coupled to bacterial density fluctuations and dynamics. Nevertheless under some specific conditions, it is possible to investigate the pattern formation as a usual viscous fingering instability. This explains the similarity and differences of patterns according to the physical bacterial suspension properties and explain the factors which favor compactness or branching. PMID:26888040

  6. The active bacterial community in a pristine confined aquifer

    NASA Astrophysics Data System (ADS)

    Flynn, Theodore M.; Sanford, Robert A.; Santo Domingo, Jorge W.; Ashbolt, Nicholas J.; Levine, Audrey D.; Bethke, Craig M.

    2012-09-01

    This study of the active bacteria residing in a pristine confined aquifer provides unexpected insights into the ecology of iron-reducing and sulfate-reducing bacteria in the subsurface. At 18 wells, we trapped the microbes that attached to aquifer sediment and used molecular techniques to examine the bacterial populations. We used multivariate statistics to compare the composition of bacterial communities among the wells with respect to the chemistry of the groundwater. We found groundwater at each well was considerably richer in ferrous iron than sulfide, indicating iron-reducing bacteria should, by established criteria, dominate the sulfate reducers. Our results show, however, that areas where groundwater contains more than a negligible amount of sulfate (>0.03 mM), populations related to sulfate reducers of the generaDesulfobacter and Desulfobulbus were of nearly equal abundance with putative iron reducers related to Geobacter, Geothrix, and Desulfuromonas. Whereas sulfate is a key discriminant of bacterial community structure, we observed no statistical relationship between the distribution of bacterial populations in this aquifer and the concentration of either ferrous iron or dissolved sulfide. These results call into question the validity of using the relative concentration of these two ions to predict the nature of bacterial activity in an aquifer. Sulfate reducers and iron reducers do not appear to be segregated into discrete zones in the aquifer, as would be predicted by the theory of competitive exclusion. Instead, we find the two groups coexist in the subsurface in what we suggest is a mutualistic relationship.

  7. Collective chemotaxis and segregation of active bacterial colonies

    PubMed Central

    Amar, M. Ben

    2016-01-01

    Still recently, bacterial fluid suspensions have motivated a lot of works, both experimental and theoretical, with the objective to understand their collective dynamics from universal and simple rules. Since some species are active, most of these works concern the strong interactions that these bacteria exert on a forced flow leading to instabilities, chaos and turbulence. Here, we investigate the self-organization of expanding bacterial colonies under chemotaxis, proliferation and eventually active-reaction. We propose a simple model to understand and quantify the physical properties of these living organisms which either give cohesion or on the contrary dispersion to the colony. Taking into account the diffusion and capture of morphogens complicates the model since it induces a bacterial density gradient coupled to bacterial density fluctuations and dynamics. Nevertheless under some specific conditions, it is possible to investigate the pattern formation as a usual viscous fingering instability. This explains the similarity and differences of patterns according to the physical bacterial suspension properties and explain the factors which favor compactness or branching. PMID:26888040

  8. Bacterial expression of human kynurenine 3-monooxygenase: solubility, activity, purification.

    PubMed

    Wilson, K; Mole, D J; Binnie, M; Homer, N Z M; Zheng, X; Yard, B A; Iredale, J P; Auer, M; Webster, S P

    2014-03-01

    Kynurenine 3-monooxygenase (KMO) is an enzyme central to the kynurenine pathway of tryptophan metabolism. KMO has been implicated as a therapeutic target in several disease states, including Huntington's disease. Recombinant human KMO protein production is challenging due to the presence of transmembrane domains, which localise KMO to the outer mitochondrial membrane and render KMO insoluble in many in vitro expression systems. Efficient bacterial expression of human KMO would accelerate drug development of KMO inhibitors but until now this has not been achieved. Here we report the first successful bacterial (Escherichia coli) expression of active FLAG™-tagged human KMO enzyme expressed in the soluble fraction and progress towards its purification. PMID:24316190

  9. Enhanced Efflux Activity Facilitates Drug Tolerance in Dormant Bacterial Cells

    PubMed Central

    Pu, Yingying; Zhao, Zhilun; Li, Yingxing; Zou, Jin; Ma, Qi; Zhao, Yanna; Ke, Yuehua; Zhu, Yun; Chen, Huiyi; Baker, Matthew A.B.; Ge, Hao; Sun, Yujie; Xie, Xiaoliang Sunney; Bai, Fan

    2016-01-01

    Summary Natural variations in gene expression provide a mechanism for multiple phenotypes to arise in an isogenic bacterial population. In particular, a sub-group termed persisters show high tolerance to antibiotics. Previously, their formation has been attributed to cell dormancy. Here we demonstrate that bacterial persisters, under β-lactam antibiotic treatment, show less cytoplasmic drug accumulation as a result of enhanced efflux activity. Consistently, a number of multi-drug efflux genes, particularly the central component TolC, show higher expression in persisters. Time-lapse imaging and mutagenesis studies further establish a positive correlation between tolC expression and bacterial persistence. The key role of efflux systems, among multiple biological pathways involved in persister formation, indicates that persisters implement a positive defense against antibiotics prior to a passive defense via dormancy. Finally, efflux inhibitors and antibiotics together effectively attenuate persister formation, suggesting a combination strategy to target drug tolerance. PMID:27105118

  10. A single subunit, Dis3, is essentially responsible for yeast exosome core activity.

    PubMed

    Dziembowski, Andrzej; Lorentzen, Esben; Conti, Elena; Séraphin, Bertrand

    2007-01-01

    The conserved core of the exosome, the major eukaryotic 3' --> 5' exonuclease, contains nine subunits that form a ring similar to the phosphorolytic bacterial PNPase and archaeal exosome, as well as Dis3. Dis3 is homologous to bacterial RNase II, a hydrolytic enzyme. Previous studies have suggested that all subunits are active 3' --> 5' exoRNases. We show here that Dis3 is responsible for exosome core activity. The purified exosome core has a hydrolytic, processive and Mg(2+)-dependent activity with characteristics similar to those of recombinant Dis3. Moreover, a catalytically inactive Dis3 mutant has no exosome core activity in vitro and shows in vivo RNA degradation phenotypes similar to those resulting from exosome depletion. In contrast, mutations in Rrp41, the only subunit carrying a conserved phosphorolytic site, appear phenotypically not different from wild-type yeast. We observed that the yeast exosome ring mediates interactions with protein partners, providing an explanation for its essential function. PMID:17173052

  11. Metatranscriptomics reveals overall active bacterial composition in caries lesions

    PubMed Central

    Simón-Soro, Aurea; Guillen-Navarro, Miriam; Mira, Alex

    2014-01-01

    Background Identifying the microbial species in caries lesions is instrumental to determine the etiology of dental caries. However, a significant proportion of bacteria in carious lesions have not been cultured, and the use of molecular methods has been limited to DNA-based approaches, which detect both active and inactive or dead microorganisms. Objective To identify the RNA-based, metabolically active bacterial composition of caries lesions at different stages of disease progression in order to provide a list of potential etiological agents of tooth decay. Design Non-cavitated enamel caries lesions (n=15) and dentin caries lesions samples (n=12) were collected from 13 individuals. RNA was extracted and cDNA was constructed, which was used to amplify the 16S rRNA gene. The resulting 780 bp polymerase chain reaction products were pyrosequenced using Titanium-plus chemistry, and the sequences obtained were used to determine the bacterial composition. Results A mean of 4,900 sequences of the 16S rRNA gene with an average read length of 661 bp was obtained per sample, giving a comprehensive view of the active bacterial communities in caries lesions. Estimates of bacterial diversity indicate that the microbiota of cavities is highly complex, each sample containing between 70 and 400 metabolically active species. The composition of these bacterial consortia varied among individuals and between caries lesions of the same individuals. In addition, enamel and dentin lesions had a different bacterial makeup. Lactobacilli were found almost exclusively in dentin cavities. Streptococci accounted for 40% of the total active community in enamel caries, and 20% in dentin caries. However, Streptococcus mutans represented only 0.02–0.73% of the total bacterial community. Conclusions The data indicate that the etiology of dental caries is tissue dependent and that the disease has a clear polymicrobial origin. The low proportion of mutans streptococci detected confirms that they

  12. Enhanced antibacterial activity of bimetallic gold-silver core-shell nanoparticles at low silver concentration

    NASA Astrophysics Data System (ADS)

    Banerjee, Madhuchanda; Sharma, Shilpa; Chattopadhyay, Arun; Ghosh, Siddhartha Sankar

    2011-12-01

    Herein we report the development of bimetallic Au@Ag core-shell nanoparticles (NPs) where gold nanoparticles (Au NPs) served as the seeds for continuous deposition of silver atoms on its surface. The core-shell structure and morphology were examined by UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). The core-shell NPs showed antibacterial activity against both Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis and Pediococcus acidilactici) bacteria at low concentration of silver present in the shell, with more efficacy against Gram negative bacteria. TEM and flow cytometric studies showed that the core-shell NPs attached to the bacterial surface and caused membrane damage leading to cell death. The enhanced antibacterial properties of Au@Ag core-shell NPs was possibly due to the more active silver atoms in the shell surrounding gold core due to high surface free energy of the surface Ag atoms owing to shell thinness in the bimetallic NP structure.Herein we report the development of bimetallic Au@Ag core-shell nanoparticles (NPs) where gold nanoparticles (Au NPs) served as the seeds for continuous deposition of silver atoms on its surface. The core-shell structure and morphology were examined by UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). The core-shell NPs showed antibacterial activity against both Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis and Pediococcus acidilactici) bacteria at low concentration of silver present in the shell, with more efficacy against Gram negative bacteria. TEM and flow cytometric studies showed that the core-shell NPs attached to the bacterial surface and caused membrane damage leading to cell death. The enhanced antibacterial properties of Au@Ag core-shell NPs was

  13. Bacterial protease triggered release of biocides from microspheres with an oily core.

    PubMed

    Craig, Marina; Amiri, Mona; Holmberg, Krister

    2015-03-01

    This study deals with controlled release of drugs to a Staphylococcus aureus infected site from microspheres with an oily core and a polymeric shell. The intended use of the microspheres is for chronic wounds and the microspheres may be administered in the form of a wash liquid or incorporated in a gel. Chronic wounds often carry infection, and the use of microspheres with drug release triggered by the bacterial infection is therefore of interest. A lipophilic drug or a model of the drug was dissolved in an oil and the oil phase was dispersed into an o/w emulsion. A nanofilm shell was then assembled around the oil droplets with the layer-by-layer technique using the two biodegradable polypeptides anionic poly-L-glutamic acid (PLGA) and cationic poly-L-lysine (PLL). Since S. aureus exudes proteases such as glutamyl endopeptidase (V8) during colonization and infection, its substrate specificity was key when assembling the nanofilm. Since V8 is known to be substrate specific to the Glu-X bond, PLGA was chosen as the terminating layer of the nanofilm. Crosslinking the nanofilm after assembly lead to increased stability of the microspheres. It was shown that in a non-infectious environment, i.e. when a human wound enzyme, HNE (human neutrophile elastase), was present, the microspheres remained intact. The staphylococcal protease V8, on the other hand, readily catalyzed degradation of the microspheres, thus releasing the drug when triggered by the infectious environment. PMID:25679492

  14. Bacterial Community Composition and Extracellular Enzyme Activity in Temperate Streambed Sediment during Drying and Rewetting

    PubMed Central

    Pohlon, Elisabeth; Ochoa Fandino, Adriana; Marxsen, Jürgen

    2013-01-01

    Droughts are among the most important disturbance events for stream ecosystems; they not only affect stream hydrology but also the stream biota. Although desiccation of streams is common in Mediterranean regions, phases of dryness in headwaters have been observed more often and for longer periods in extended temperate regions, including Central Europe, reflecting global climate change and enhanced water withdrawal. The effects of desiccation and rewetting on the bacterial community composition and extracellular enzyme activity, a key process in the carbon flow of streams and rivers, were investigated in a typical Central European stream, the Breitenbach (Hesse, Germany). Wet streambed sediment is an important habitat in streams. It was sampled and exposed in the laboratory to different drying scenarios (fast, intermediate, slow) for 13 weeks, followed by rewetting of the sediment from the fast drying scenario via a sediment core perfusion technique for 2 weeks. Bacterial community structure was analyzed using CARD-FISH and TGGE, and extracellular enzyme activity was assessed using fluorogenic model substrates. During desiccation the bacterial community composition shifted toward composition in soil, exhibiting increasing proportions of Actinobacteria and Alphaproteobacteria and decreasing proportions of Bacteroidetes and Betaproteobacteria. Simultaneously the activities of extracellular enzymes decreased, most pronounced with aminopeptidases and less pronounced with enzymes involved in the degradation of polymeric carbohydrates. After rewetting, the general ecosystem functioning, with respect to extracellular enzyme activity, recovered after 10 to 14 days. However, the bacterial community composition had not yet achieved its original composition as in unaffected sediments within this time. Thus, whether the bacterial community eventually recovers completely after these events remains unknown. Perhaps this community undergoes permanent changes, especially after

  15. Structure of a bacterial toxin-activating acyltransferase

    PubMed Central

    Greene, Nicholas P.; Hughes, Colin; Koronakis, Vassilis

    2015-01-01

    Secreted pore-forming toxins of pathogenic Gram-negative bacteria such as Escherichia coli hemolysin (HlyA) insert into host–cell membranes to subvert signal transduction and induce apoptosis and cell lysis. Unusually, these toxins are synthesized in an inactive form that requires posttranslational activation in the bacterial cytosol. We have previously shown that the activation mechanism is an acylation event directed by a specialized acyl-transferase that uses acyl carrier protein (ACP) to covalently link fatty acids, via an amide bond, to specific internal lysine residues of the protoxin. We now reveal the 2.15-Å resolution X-ray structure of the 172-aa ApxC, a toxin-activating acyl-transferase (TAAT) from pathogenic Actinobacillus pleuropneumoniae. This determination shows that bacterial TAATs are a structurally homologous family that, despite indiscernible sequence similarity, form a distinct branch of the Gcn5-like N-acetyl transferase (GNAT) superfamily of enzymes that typically use acyl-CoA to modify diverse bacterial, archaeal, and eukaryotic substrates. A combination of structural analysis, small angle X-ray scattering, mutagenesis, and cross-linking defined the solution state of TAATs, with intermonomer interactions mediated by an N-terminal α-helix. Superposition of ApxC with substrate-bound GNATs, and assay of toxin activation and binding of acyl-ACP and protoxin peptide substrates by mutated ApxC variants, indicates the enzyme active site to be a deep surface groove. PMID:26016525

  16. Antibiofilm activity of Dendrophthoe falcata against different bacterial pathogens.

    PubMed

    Karthikeyan, Alagarsamy; Rameshkumar, Ramakrishnan; Sivakumar, Nallusamy; Al Amri, Issa S; Karutha Pandian, Shunmugiah; Ramesh, Manikandan

    2012-12-01

    Dendrophthoe falcata is a hemiparasitic plant commonly used for ailments such as ulcers, asthma, impotence, paralysis, skin diseases, menstrual troubles, pulmonary tuberculosis, and wounds. In this context, the validations of the traditional claim that the leaf extract of D. falcata possesses antibiofilm and anti-quorum sensing activity against different bacterial pathogens were assessed. The bacterial biofilms were quantified by crystal violet staining. Among the 17 bacterial pathogens screened, the methanolic fraction of the leaf extract clearly demonstrated antibiofilm activity for Proteus mirabilis, Vibrio vulnificus, Aeromonas hydrophila, Shigella sonnei, Chromobacterium violaceum ATCC 12472, Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio cholerae, and Proteus vulgaris. At biofilm inhibitory concentrations, biofilm formation was reduced by up to 70-90 %. Furthermore, the potential quorum-sensing activity of the leaf extract was tested by agar well diffusion using Chromobacterium violaceum (ATCC 12472 & CV O26) reporter strains. The inhibition of violacein production may be due to direct or indirect interference on QS by active constituents or the interactive effect of different phytocompounds present in the extracts. This is the first report on antibiofilm and QS activity of D. falcata leaf extracts, signifying the scope for development of complementary medicine for biofilm-associated infections. PMID:23115018

  17. Analysis of Structure and Composition of Bacterial Core Communities in Mature Drinking Water Biofilms and Bulk Water of a Citywide Network in Germany

    PubMed Central

    Henne, Karsten; Kahlisch, Leila; Brettar, Ingrid

    2012-01-01

    The bacterial core communities of bulk water and corresponding biofilms of a more than 20-year-old drinking water network were compared using 16S rRNA single-strand confirmation polymorphism (SSCP) fingerprints based on extracted DNA and RNA. The structure and composition of the bacterial core community in the bulk water was highly similar (>70%) across the city of Braunschweig, Germany, whereas all biofilm samples contained a unique community with no overlapping phylotypes from bulk water. Biofilm samples consisted mainly of Alphaproteobacteria (26% of all phylotypes), Gammaproteobacteria (11%), candidate division TM6 (11%), Chlamydiales (9%), and Betaproteobacteria (9%). The bulk water community consisted primarily of Bacteroidetes (25%), Betaproteobacteria (20%), Actinobacteria (16%), and Alphaproteobacteria (11%). All biofilm communities showed higher relative abundances of single phylotypes and a reduced richness compared to bulk water. Only biofilm communities sampled at nearby sampling points showed similar communities irrespective of support materials. In all of our bulk water studies, the community composition determined from 16S rRNA was completely different from the 16S rRNA gene-based community composition, whereas in biofilms both molecular fractions resulted in community compositions that were similar to each other. We hypothesize that a higher fraction of active bacterial phylotypes and a better protection from oxidative stress in drinking water biofilms are responsible for this higher similarity. PMID:22389373

  18. Systematic review of core muscle activity during physical fitness exercises.

    PubMed

    Martuscello, Jason M; Nuzzo, James L; Ashley, Candi D; Campbell, Bill I; Orriola, John J; Mayer, John M

    2013-06-01

    A consensus has not been reached among strength and conditioning specialists regarding what physical fitness exercises are most effective to stimulate activity of the core muscles. Thus, the purpose of this article was to systematically review the literature on the electromyographic (EMG) activity of 3 core muscles (lumbar multifidus, transverse abdominis, quadratus lumborum) during physical fitness exercises in healthy adults. CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, PubMed, SPORTdiscus, and Web of Science databases were searched for relevant articles using a search strategy designed by the investigators. Seventeen studies enrolling 252 participants met the review's inclusion/exclusion criteria. Physical fitness exercises were partitioned into 5 major types: traditional core, core stability, ball/device, free weight, and noncore free weight. Strength of evidence was assessed and summarized for comparisons among exercise types. The major findings of this review with moderate levels of evidence indicate that lumbar multifidus EMG activity is greater during free weight exercises compared with ball/device exercises and is similar during core stability and ball/device exercises. Transverse abdominis EMG activity is similar during core stability and ball/device exercises. No studies were uncovered for quadratus lumborum EMG activity during physical fitness exercises. The available evidence suggests that strength and conditioning specialists should focus on implementing multijoint free weight exercises, rather than core-specific exercises, to adequately train the core muscles in their athletes and clients. PMID:23542879

  19. Role of Microglial Activation in the Pathophysiology of Bacterial Meningitis.

    PubMed

    Barichello, Tatiana; Generoso, Jaqueline S; Simões, Lutiana R; Goularte, Jessica A; Petronilho, Fabricia; Saigal, Priyanka; Badawy, Marwa; Quevedo, João

    2016-04-01

    Bacterial meningitis is a life-threatening infection associated with cognitive impairment in many survivors. The pathogen invades the central nervous system (CNS) by penetrating through the luminal side of the cerebral endothelium, which is an integral part of the blood-brain barrier. The replication of bacteria within the subarachnoid space occurs concomitantly with the release of their compounds that are highly immunogenic. These compounds known as pathogen-associated molecular patterns (PAMPs) may lead to both an increase in the inflammatory response in the host and also microglial activation. Microglia are the resident macrophages of the CNS which, when activated, can trigger a host of immunological pathways. Classical activation increases the production of pro-inflammatory cytokines, chemokines, and reactive oxygen species, while alternative activation is implicated in the inhibition of inflammation and restoration of homeostasis. The inflammatory response from classical microglial activation can facilitate the elimination of invasive microorganisms; however, excessive or extended microglial activation can result in neuronal damage and eventually cell death. This review aims to discuss the role of microglia in the pathophysiology of bacterial meningitis as well as the process of microglial activation by PAMPs and by endogenous constituents that are normally released from damaged cells known as danger-associated molecular patterns (DAMPs). PMID:25744564

  20. Bacterial communities in two Antarctic ice cores analyzed by 16S rRNA gene sequencing analysis

    NASA Astrophysics Data System (ADS)

    Segawa, Takahiro; Ushida, Kazunari; Narita, Hideki; Kanda, Hiroshi; Kohshima, Shiro

    2010-08-01

    Antarctic ice cores could preserve ancient airborne microorganisms. We examined bacteria in two Antarctic ice core samples, an interglacial age sample from Mizuho Base and a glacial age sample from the Yamato Mountains, by 16S rRNA gene sequencing analysis. Bacterial density, the number of bacterial OTUs and Simpson’s diversity index was larger in the Mizuho sample than in the Yamato sample. The 16S rDNA clone library from the Mizuho sample was dominated by the phylum Firmicutes, while the large part of that from the Yamato sample was composed of the Gamma proteobacteria group. Major sources of these identified bacteria estimated from their database records also differed between the samples: in the Mizuho sample bacterial species recorded from animals were higher than that of the Yamato sample, while in the Yamato sample bacteria from aquatic and snow-ice environments were higher than that of the Mizuho sample. The results suggest that these bacteria were past airborne bacteria that would vary in density, diversity and species composition depending on global environmental change. Our results imply that bacteria in Antarctic ice cores could be used as new environmental markers for past environmental studies.

  1. Activity and stability of a complex bacterial soil community under simulated Martian conditions

    NASA Astrophysics Data System (ADS)

    Hansen, Aviaja Anna; Merrison, Jonathan; Nørnberg, Per; Aagaard Lomstein, Bente; Finster, Kai

    2005-04-01

    A simulation experiment with a complex bacterial soil community in a Mars simulation chamber was performed to determine the effect of Martian conditions on community activity, stability and survival. At three different depths in the soil core short-term effects of Martian conditions with and without ultraviolet (UV) exposure corresponding to 8 Martian Sol were compared. Community metabolic activities and functional diversity, measured as glucose respiration and versatility in substrate utilization, respectively, decreased after UV exposure, whereas they remained unaffected by Martian conditions without UV exposure. In contrast, the numbers of culturable bacteria and the genetic diversity were unaffected by the simulated Martian conditions both with and without UV exposure. The genetic diversity of the soil community and of the colonies grown on agar plates were evaluated by denaturant gradient gel electrophoresis (DGGE) on DNA extracts. Desiccation of the soil prior to experimentation affected the functional diversity by decreasing the versatility in substrate utilization. The natural dominance of endospores and Gram-positive bacteria in the investigated Mars-analogue soil may explain the limited effect of the Mars incubations on the survival and community structure. Our results suggest that UV radiation and desiccation are major selecting factors on bacterial functional diversity in terrestrial bacterial communities incubated under simulated Martian conditions. Furthermore, these results suggest that forward contamination of Mars is a matter of great concern in future space missions.

  2. Disturbance opens recruitment sites for bacterial colonization in activated sludge.

    PubMed

    Vuono, David C; Munakata-Marr, Junko; Spear, John R; Drewes, Jörg E

    2016-01-01

    Little is known about the role of immigration in shaping bacterial communities or the factors that may dictate success or failure of colonization by bacteria from regional species pools. To address these knowledge gaps, the influence of bacterial colonization into an ecosystem (activated sludge bioreactor) was measured through a disturbance gradient (successive decreases in the parameter solids retention time) relative to stable operational conditions. Through a DNA sequencing approach, we show that the most abundant bacteria within the immigrant community have a greater probability of colonizing the receiving ecosystem, but mostly as low abundance community members. Only during the disturbance do some of these bacterial populations significantly increase in abundance beyond background levels and in few cases become dominant community members post-disturbance. Two mechanisms facilitate the enhanced enrichment of immigrant populations during disturbance: (i) the availability of resources left unconsumed by established species and (ii) the increased availability of niche space for colonizers to establish and displace resident populations. Thus, as a disturbance decreases local diversity, recruitment sites become available to promote colonization. This work advances our understanding of microbial resource management and diversity maintenance in complex ecosystems. PMID:25727891

  3. Isolated HIV-1 core is active for reverse transcription.

    PubMed

    Warrilow, David; Stenzel, Deborah; Harrich, David

    2007-01-01

    Whether purified HIV-1 virion cores are capable of reverse transcription or require uncoating to be activated is currently controversial. To address this question we purified cores from a virus culture and tested for the ability to generate authentic reverse transcription products. A dense fraction (approximately 1.28 g/ml) prepared without detergent, possibly derived from disrupted virions, was found to naturally occur as a minor sub-fraction in our preparations. Core-like particles were identified in this active fraction by electron microscopy. We are the first to report the detection of authentic strong-stop, first-strand transfer and full-length minus strand products in this core fraction without requirement for an uncoating activity. PMID:17956635

  4. Bacterial activities driving arsenic speciation and solubility in marine sediments

    NASA Astrophysics Data System (ADS)

    Battaglia-Brunet, F.; Seby, F.; Crouzet, C.; Joulian, C.; Mamindy-Pajany, Y.; Guezennec, A. G.; Hurel, C.; Marmier, N.; Bataillard, P.

    2012-04-01

    Harbour and marina sediments represent particular environments, with high concentrations in organic carbon and pollutants. Over 50 million m3 of marine sediments are dredged every year in French maritime and commercial ports, to maintain the water depth suitable for navigation, and the most part of them is discharged in deeper sea zones. The present study aimed to elucidate, using a range of complementary approaches, the influence of bacterial activity on arsenic speciation and mobility in marina sediments. Two sites were considered: L'Estaque, impacted by metallurgical activities and by the commercial port of Marseille, and St-Mandrier, less polluted, affected by classical chemical pollutants associated to professional and recreational boating. Arsenic concentration was noticeably higher in l'Estaque sediment (200-350 mg/kg) than in St-Mandrier sediment (15-50 mg/kg). In the solid phases, As(III) was the dominant species in L'Estaque sediment, whereas As(V) was the main form in St Mandrier sediment. At both sites, arsenic was the major trace element detected in interstitial water. Free sulfide and thio-arsenic complexes were detected in the interstitial water of l'Estaque sediment, suggesting a role of sulfate-reduction bacterial activity on arsenic solubility. Anaerobic microcosm experiments confirmed this hypothesis, as stimulation of sulfate-reduction induced a dramatic increase of arsenic concentration in the liquid phase, linked to the formation of soluble thio-arsenic complexes. Nevertheless, microcosms performed in aerobic conditions showed that bacterial activity globally decreased the transfer of arsenic from the sediment toward the overlying water. A red-brown fine layer developed at the sediment-water interface. Altogether, these results suggest that the sediment-water interface zone and the close transition area between aerobic and anaerobic conditions host intense biogeochemical reactions involving As, Fe and S species. These reactions most probably

  5. Simultaneous spatiotemporal mapping of in situ pH and bacterial activity within an intact 3D microcolony structure.

    PubMed

    Hwang, Geelsu; Liu, Yuan; Kim, Dongyeop; Sun, Victor; Aviles-Reyes, Alejandro; Kajfasz, Jessica K; Lemos, Jose A; Koo, Hyun

    2016-01-01

    Biofilms are comprised of bacterial-clusters (microcolonies) enmeshed in an extracellular matrix. Streptococcus mutans can produce exopolysaccharides (EPS)-matrix and assemble microcolonies with acidic microenvironments that can cause tooth-decay despite the surrounding neutral-pH found in oral cavity. How the matrix influences the pH and bacterial activity locally remains unclear. Here, we simultaneously analyzed in situ pH and gene expression within intact biofilms and measured the impact of damage to the surrounding EPS-matrix. The spatiotemporal changes of these properties were characterized at a single-microcolony level following incubation in neutral-pH buffer. The middle and bottom-regions as well as inner-section within the microcolony 3D structure were resistant to neutralization (vs. upper and peripheral-region), forming an acidic core. Concomitantly, we used a green fluorescent protein (GFP) reporter to monitor expression of the pH-responsive atpB (PatpB::gfp) by S. mutans within microcolonies. The atpB expression was induced in the acidic core, but sharply decreased at peripheral/upper microcolony regions, congruent with local pH microenvironment. Enzymatic digestion of the surrounding matrix resulted in nearly complete neutralization of microcolony interior and down-regulation of atpB. Altogether, our data reveal that biofilm matrix facilitates formation of an acidic core within microcolonies which in turn activates S. mutans acid-stress response, mediating both the local environment and bacterial activity in situ. PMID:27604325

  6. Simultaneous spatiotemporal mapping of in situ pH and bacterial activity within an intact 3D microcolony structure

    PubMed Central

    Hwang, Geelsu; Liu, Yuan; Kim, Dongyeop; Sun, Victor; Aviles-Reyes, Alejandro; Kajfasz, Jessica K.; Lemos, Jose A.; Koo, Hyun

    2016-01-01

    Biofilms are comprised of bacterial-clusters (microcolonies) enmeshed in an extracellular matrix. Streptococcus mutans can produce exopolysaccharides (EPS)-matrix and assemble microcolonies with acidic microenvironments that can cause tooth-decay despite the surrounding neutral-pH found in oral cavity. How the matrix influences the pH and bacterial activity locally remains unclear. Here, we simultaneously analyzed in situ pH and gene expression within intact biofilms and measured the impact of damage to the surrounding EPS-matrix. The spatiotemporal changes of these properties were characterized at a single-microcolony level following incubation in neutral-pH buffer. The middle and bottom-regions as well as inner-section within the microcolony 3D structure were resistant to neutralization (vs. upper and peripheral-region), forming an acidic core. Concomitantly, we used a green fluorescent protein (GFP) reporter to monitor expression of the pH-responsive atpB (PatpB::gfp) by S. mutans within microcolonies. The atpB expression was induced in the acidic core, but sharply decreased at peripheral/upper microcolony regions, congruent with local pH microenvironment. Enzymatic digestion of the surrounding matrix resulted in nearly complete neutralization of microcolony interior and down-regulation of atpB. Altogether, our data reveal that biofilm matrix facilitates formation of an acidic core within microcolonies which in turn activates S. mutans acid-stress response, mediating both the local environment and bacterial activity in situ. PMID:27604325

  7. A bacterial glycan core linked to surface (S)-layer proteins modulates host immunity through Th17 suppression

    PubMed Central

    Settem, Rajendra P.; Honma, Kiyonobu; Nakajima, Takuma; Phansopa, Chatchawal; Roy, Sumita; Stafford, Graham P.; Sharma, Ashu

    2014-01-01

    Tannerella forsythia is a pathogen implicated in periodontitis, an inflammatory disease of the tooth supporting tissues often leading to tooth loss. This key periodontal pathogen is decorated with a unique glycan core O-glycosidically linked to the bacterium’s proteinacious surface(S)-layer lattice and other glycoproteins. Herein we show that the terminal motif of this glycan core acts to modulate dendritic cell effector functions to suppress Th17 responses. In contrast to the wild-type bacterial strain, infection with a mutant strain lacking the complete S-layer glycan core induced robust Th17 and reduced periodontal bone loss in mice. Our findings demonstrate that surface glycosylation of this pathogen acts to ensure its persistence in the host by suppressing Th17 responses. In addition our data suggest that the bacterium then induces the TLR2-Th2 inflammatory axis that has previously shown to cause bone destruction. Our study provides a biological basis for pathogenesis and opens opportunities in exploiting bacterial glycans as therapeutic targets against periodontitis and a range of other infectious diseases. PMID:22968422

  8. Microbial population, activity, and phylogenetic diversity in the subseafloor core sediment from the Sea of Okhotsk

    NASA Astrophysics Data System (ADS)

    Inagaki, F.; Suzuki, M.; Takai, K.; Nealson, K. H.; Horikoshi, K.

    2002-12-01

    Subseafloor environments has already been recognized as the largest biosphere on the planet Earth, however, the microbial diversity and activity has been still poorly understood, even in their impacts on biogeochemical processes, tectonic settings, and paleoenvironmental events. We demonstrate here the evaluation of microbial community structure and active habitats in deeply buried cold marine sediments collected from the Sea of Okhotsk by a combined use of molecular ecological surveys and culturing assays. The piston core sediment (MD01-2412) was collected by IMAGES (International Marine Global Change Study) Project from the southeastern Okhotsk Sea, June 2001. The total recovered length was about 58m. The lithology of the core sediment was mainly constructed from pelagic clay (PC) and volcanic ash layers (Ash). We collected aseptically the most inside core parts from 16 sections at different depths for microbiological study. The direct count of DAPI-stained cells revealed that the cells in Ash samples were present 1.2 to 2.2 times higher than in PC samples. The quantitative-PCR of 16S rDNA between bacterial and archaeal rDNA suggested that the increased population density in Ash layers was caused by the bacterial components. We studied approximately 650 and 550 sequences from bacterial and archaeal rDNA clone libraries, respectively. The similarity and phylogenetic analyses revealed that the microbial community structures were apparently different between in Ash layers and PC samples. From bacterial rDNA clone libraries, the members within gamma-Proteobacteria such as genera Halomonas, Shewanella, Psychromonas and Methylosinus were predominantly detected in Ash layers whereas the Dehalococcoides group and delta-Proteobacteria were major bacterial components in PC samples. From archaeal libraries, the sequences from Ash and PC samples were affiliated into the clusters represented by the environmental sequences obtained from terrestrial and deep-sea environments

  9. Hydrophobic Core Flexibility Modulates Enzyme Activity in HIV-1 Protease

    SciTech Connect

    Mittal, Seema; Cai, Yufeng; Nalam, Madhavi N.L.; Bolon, Daniel N.A.; Schiffer, Celia A.

    2012-09-11

    Human immunodeficiency virus Type-1 (HIV-1) protease is crucial for viral maturation and infectivity. Studies of protease dynamics suggest that the rearrangement of the hydrophobic core is essential for enzyme activity. Many mutations in the hydrophobic core are also associated with drug resistance and may modulate the core flexibility. To test the role of flexibility in protease activity, pairs of cysteines were introduced at the interfaces of flexible regions remote from the active site. Disulfide bond formation was confirmed by crystal structures and by alkylation of free cysteines and mass spectrometry. Oxidized and reduced crystal structures of these variants show the overall structure of the protease is retained. However, cross-linking the cysteines led to drastic loss in enzyme activity, which was regained upon reducing the disulfide cross-links. Molecular dynamics simulations showed that altered dynamics propagated throughout the enzyme from the engineered disulfide. Thus, altered flexibility within the hydrophobic core can modulate HIV-1 protease activity, supporting the hypothesis that drug resistant mutations distal from the active site can alter the balance between substrate turnover and inhibitor binding by modulating enzyme activity.

  10. Compact radio cores in radio-quiet active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Maini, A.; Prandoni, I.; Norris, R. P.; Giovannini, G.; Spitler, L. R.

    2016-04-01

    Context. The mechanism of radio emission in radio-quiet (RQ) active galactic nuclei (AGNs) is still debated and might arise from the central AGN, from star formation activity in the host, or from either of these sources. A direct detection of compact and bright radio cores embedded in sources that are classified as RQ can unambiguously determine whether a central AGN significantly contributes to the radio emission. Aims: We search for compact, high-surface-brightness radio cores in RQ AGNs that are caused unambiguously by AGN activity. Methods: We used the Australian Long Baseline Array to search for compact radio cores in four RQ AGNs located in the Extended Chandra Deep Field South (ECDFS). We also targeted four radio-loud (RL) AGNs as a control sample. Results: We detected compact and bright radio cores in two AGNs that are classified as RQ and in one that is classified as RL. Two RL AGNs were not imaged because the quality of the observations was too poor. Conclusions: We report on a first direct evidence of radio cores in RQ AGNs at cosmological redshifts. Our detections show that some of the sources that are classified as RQ contain an active AGN that can contribute significantly (~50% or more) to the total radio emission.

  11. Ubiquitin Activates Patatin-Like Phospholipases from Multiple Bacterial Species

    PubMed Central

    Anderson, David M.; Sato, Hiromi; Dirck, Aaron T.; Feix, Jimmy B.

    2014-01-01

    Phospholipase A2 enzymes are ubiquitously distributed throughout the prokaryotic and eukaryotic kingdoms and are utilized in a wide array of cellular processes and physiological and immunological responses. Several patatin-like phospholipase homologs of ExoU from Pseudomonas aeruginosa were selected on the premise that ubiquitin activation of this class of bacterial enzymes was a conserved process. We found that ubiquitin activated all phospholipases tested in both in vitro and in vivo assays via a conserved serine-aspartate catalytic dyad. Ubiquitin chains versus monomeric ubiquitin were superior in inducing catalysis, and ubiquitin-like proteins failed to activate phospholipase activity. Toxicity studies in a prokaryotic dual-expression system grouped the enzymes into high- and low-toxicity classes. Toxicity measured in eukaryotic cells also suggested a two-tiered classification but was not predictive of the severity of cellular damage, suggesting that each enzyme may correspond to unique properties perhaps based on its specific biological function. Additional studies on lipid binding preference suggest that some enzymes in this family may be differentially sensitive to phosphatidyl-4,5-bisphosphate in terms of catalytic activation enhancement and binding affinity. Further analysis of the function and amino acid sequences of this enzyme family may lead to a useful approach to formulating a unifying model of how these phospholipases behave after delivery into the cytoplasmic compartment. PMID:25404699

  12. Core Muscle Activity, Exercise Preference, and Perceived Exertion during Core Exercise with Elastic Resistance versus Machine

    PubMed Central

    Vinstrup, Jonas; Sundstrup, Emil; Brandt, Mikkel; Jakobsen, Markus D.; Calatayud, Joaquin; Andersen, Lars L.

    2015-01-01

    Objectives. To investigate core muscle activity, exercise preferences, and perceived exertion during two selected core exercises performed with elastic resistance versus a conventional training machine. Methods. 17 untrained men aged 26–67 years participated in surface electromyography (EMG) measurements of five core muscles during torso-twists performed from left to right with elastic resistance and in the machine, respectively. The order of the exercises was randomized and each exercise consisted of 3 repetitions performed at a 10 RM load. EMG amplitude was normalized (nEMG) to maximum voluntary isometric contraction (MVC). Results. A higher right erector spinae activity in the elastic exercise compared with the machine exercise (50% [95% CI 36–64] versus 32% [95% CI 18–46] nEMG) was found. By contrast, the machine exercise, compared with the elastic exercise, showed higher left external oblique activity (77% [95% CI 64–90] versus 54% [95% CI 40–67] nEMG). For the rectus abdominis, right external oblique, and left erector spinae muscles there were no significant differences. Furthermore, 76% preferred the torso-twist with elastic resistance over the machine exercise. Perceived exertion (Borg CR10) was not significantly different between machine (5.8 [95% CI 4.88–6.72]) and elastic exercise (5.7 [95% CI 4.81–6.59]). Conclusion. Torso-twists using elastic resistance showed higher activity of the erector spinae, whereas torso-twist in the machine resulted in higher activity of the external oblique. For the remaining core muscles the two training modalities induced similar muscular activation. In spite of similar perceived exertion the majority of the participants preferred the exercise using elastic resistance. PMID:26557405

  13. Discordant temporal development of bacterial phyla and the emergence of core in the fecal microbiota of young children.

    PubMed

    Cheng, Jing; Ringel-Kulka, Tamar; Heikamp-de Jong, Ineke; Ringel, Yehuda; Carroll, Ian; de Vos, Willem M; Salojärvi, Jarkko; Satokari, Reetta

    2016-04-01

    The colonization pattern of intestinal microbiota during childhood may impact health later in life, but children older than 1 year are poorly studied. We followed healthy children aged 1-4 years (n=28) for up to 12 months, during which a synbiotic intervention and occasional antibiotics intake occurred, and compared them with adults from the same region. Microbiota was quantified with the HITChip phylogenetic microarray and analyzed with linear mixed effects model and other statistical approaches. Synbiotic administration increased the stability of Actinobacteria and antibiotics decreased Clostridium cluster XIVa abundance. Bacterial diversity did not increase in 1- to 5-year-old children and remained significantly lower than in adults. Actinobacteria, Bacilli and Clostridium cluster IV retained child-like abundances, whereas some other groups were converting to adult-like profiles. Microbiota stability increased, with Bacteroidetes being the main contributor. The common core of microbiota in children increased with age from 18 to 25 highly abundant genus-level taxa, including several butyrate-producing organisms, and developed toward an adult-like composition. In conclusion, intestinal microbiota is not established before 5 years of age and diversity, core microbiota and different taxa are still developing toward adult-type configuration. Discordant development patterns of bacterial phyla may reflect physiological development steps in children. PMID:26430856

  14. Activity and bacterial diversity of snow around Russian Antarctic stations.

    PubMed

    Lopatina, Anna; Krylenkov, Vjacheslav; Severinov, Konstantin

    2013-11-01

    The diversity and temporal dynamics of bacterial communities in pristine snow around two Russian Antarctic stations was investigated. Taxonomic analysis of rDNA libraries revealed that snow communities were dominated by bacteria from a small number of operational taxonomic units (OTUs) that underwent dramatic swings in abundance between the 54th (2008-2009) and 55th (2009-2010) Russian Antarctic expeditions. Moreover, analysis of the 55th expedition samples indicated that there was very little, if any, correspondence in abundance of clones belonging to the same OTU present in rDNA and rRNA libraries. The latter result suggests that most rDNA clones originate from bacteria that are not alive and/or active and may have been deposited on the snow surface from the atmosphere. In contrast, clones most abundant in rRNA libraries (mostly belonging to Variovorax, Janthinobacterium, Pseudomonas, and Sphingomonas genera) may be considered as endogenous Antarctic snow inhabitants. PMID:24012540

  15. Substrate Trafficking And Dioxygen Activation in Bacterial Multicomponent Monooxygenases

    SciTech Connect

    Murray, L.J.; Lippard, S.J.

    2009-06-03

    Non-heme carboxylate-bridged diiron centers in the hydroxylase components of the bacterial multicomponent monooxygenases process four substrates during catalysis: electrons, protons, dioxygen, and hydrocarbons. Understanding how protein-protein interactions mediate the transport of these substrates to the diiron center to achieve the selective oxidation of the hydrocarbon is a significant challenge. In this Account, we summarize our current knowledge of these processes with a focus on the methane monooxygenase system. We also describe recent results for the toluene/o-xylene monooxygenase and phenol hydroxylase systems from Pseudomonas sporium OX1. The observation in these latter systems of a diiron(III) oxygenated intermediate having different Moessbauer parameters from analogous species in other carboxylate-bridged diiron proteins is discussed. The results indicate that the ability of the protein framework to tune the reactivity of the diiron center at structurally similar active sites is substantially more complex than previously recognized.

  16. Assessment of denitrifying bacterial composition in activated sludge.

    PubMed

    Srinandan, C S; Shah, Mrinal; Patel, Bhavita; Nerurkar, Anuradha S

    2011-10-01

    The abundance and structure of denitrifying bacterial community in different activated sludge samples were assessed, where the abundance of denitrifying functional genes showed nirS in the range of 10(4)-10(5), nosZ with 10(4)-10(6) and 16S rRNA gene in the range 10(9)-10(10) copy number per ml of sludge. The culturable approach revealed Pseudomonas sp. and Alcaligenes sp. to be numerically high, whereas culture independent method showed betaproteobacteria to dominate the sludge samples. Comamonas sp. and Pseudomonas fluorescens isolates showed efficient denitrification, while Pseudomonas mendocina, Pseudomonas stutzeri and Brevundimonas diminuta accumulated nitrite during denitrification. Numerically dominant RFLP OTUs of the nosZ gene from the fertilizer factory sludge samples clustered with the known isolates of betaproteobacteria. The data also suggests the presence of different truncated denitrifiers with high numbers in sludge habitat. PMID:21868215

  17. Bacterial lifestyle shapes the regulation of stringent response activation

    PubMed Central

    Boutte, Cara C.; Crosson, Sean

    2014-01-01

    Bacteria inhabit enormously diverse niches and have a correspondingly large array of regulatory mechanisms to adapt to often inhospitable and variable environments. The stringent response allows bacteria to quickly reprogram transcription in response to changes in nutrient availability. Although the proteins controlling this response are conserved in almost all bacterial species, recent work has illuminated considerable diversity in the starvation cues and regulatory mechanisms that activate stringent signaling proteins in bacteria from different environments. In this review we describe the signals and genetic circuitries that control the stringent signaling systems of a copiotroph, a bacteriovore, an oligotroph and a mammalian pathogen – Escherichia coli, Myxococcus xanthus, Caulobacter crescentus and Mycobacterium tuberculosis, respectively – and discuss how control of the stringent response in these species is adapted to their particular lifestyles. PMID:23419217

  18. A Bacterial Ortholog of Class II Lysyl-tRNA Synthetase Activates Lysine

    PubMed Central

    Ambrogelly, Alexandre; O’Donoghue, Patrick; Söll, Dieter; Moses, Sharath

    2010-01-01

    Aminoacyl-tRNA synthetases produce aminoacyl-tRNAs, essential substrates for accurate protein synthesis. Beyond their central role in translation some of these enzymes or their orthologs are recruited for alternative functions, not always related to their primary cellular role. We investigate here the enzymatic properties of GenX (also called PoxA and YjeA), an ortholog of bacterial class II lysyl-tRNA synthetase. GenX is present in most Gram-negative bacteria and is homologous to the catalytic core of lysyl-tRNA synthetase, but it lacks the amino terminal anticodon binding domain of the latter enzyme. We show that, in agreement with its well-conserved lysine binding site, GenX can activate in vitro L-lysine and lysine analogs, but does not acylate tRNALys or other cellular RNAs. PMID:20580719

  19. Microelectrode Measurements of the Activity Distribution in Nitrifying Bacterial Aggregates

    PubMed Central

    de Beer, D.; van den Heuvel, J. C.; Ottengraf, S. P. P.

    1993-01-01

    Microelectrodes for ammonium, oxygen, nitrate, and pH were used to study nitrifying aggregates grown in a fluidized-bed reactor. Local reactant fluxes and distribution of microbial activity could be determined from the microprofiles. The interfacial fluxes of the reactants closely reflected the stoichiometry of bacterial nitrification. Both ammonium consumption and nitrate production were localized in the outer shells, with a thickness of approximately 100 to 120 μm, of the aggregates. Under conditions in which ammonium and oxygen penetrated the whole aggregate, nitrification was restricted to this zone; oxygen was consumed in the central parts of the aggregates as well, probably because of oxidation of dead biomass. A sudden increase of the oxygen concentration to saturation (pure oxygen) was inhibitory to nitrification. The pH profiles showed acidification in the aggregates, but not to an inhibitory level. The distribution of activity was determined by the penetration depth of oxygen during aggregate development in the reactor. Mass transfer was significantly limited by the boundary layer surrounding the aggregates. Microelectrode measurements showed that the thickness of this layer was correlated with the diffusion coefficient of the species. Determination of the distribution of nitrifying activity required the use of ammonium or nitrate microelectrodes, whereas the use of oxygen microelectrodes alone would lead to erroneous results. Images PMID:16348875

  20. Peptidotriazoles with antimicrobial activity against bacterial and fungal plant pathogens.

    PubMed

    Güell, Imma; Micaló, Lluís; Cano, Laura; Badosa, Esther; Ferre, Rafael; Montesinos, Emilio; Bardají, Eduard; Feliu, Lidia; Planas, Marta

    2012-01-01

    We designed and prepared peptidotriazoles based on the antimicrobial peptide BP100 (LysLysLeuPheLysLysIleLeuLysTyrLeu-NH(2)) by introducing a triazole ring in the peptide backbone or onto the side chain of a selected residue. These compounds were screened for their in vitro growth inhibition of bacterial and fungal phytopathogens, and for their cytotoxic effects on eukaryotic cells and tobacco leaves. Their proteolytic susceptibility was also analyzed. The antibacterial activity and the hemolysis were influenced by the amino acid that was modified with the triazole as well as by the absence of presence of a substituent in this heterocyclic ring. We identified sequences active against the bacteria Xanthomonas axonopodis pv. vesicatoria, Erwinia amylovora, Pseudomonas syringae pv. syringae (MIC of 1.6-12.5 μM), and against the fungi Fusarium oxysporum (MIC<6.2-12.5 μM) with low hemolytic activity (0-23% at 50 μM), high stability to protease digestion and no phytotoxicity. These peptidotriazoles constitute good candidates to design new antimicrobial agents. PMID:22198367

  1. Active core rewarming avoids bioelectrical impedance changes in postanesthetic patients

    PubMed Central

    2011-01-01

    Background Postoperative hypothermia is a common cause of complications in patients who underwent laparoscopic cholecystectomy. Hypothermia is known to elicit electrophysiological, biochemical, and cellular alterations thus leading to changes in the active and passive membrane properties. These changes might influence the bioelectrical impedance (BI). Our aim was to determine whether the BI depends on the core temperature. Methods We studied 60 patients (52 female and 8 male) age 40 to 80 years with an ASA I-II classification that had undergone laparoscopic cholecystectomy under balanced inhalation anesthesia. The experimental group (n = 30) received active core rewarming during the transanesthetic and postanesthesic periods. The control group (n = 30) received passive external rewarming. The BI was recorded by using a 4-contact electrode system to collect dual sets of measurements in the deltoid muscle. The body temperature, hemodynamic variables, respiratory rate, blood-gas levels, biochemical parameters, and shivering were also measured. The Mann-Whitney unpaired t-test was used to determine the differences in shivering between each group at each measurement period. Measurements of body temperature, hemodynamics variables, respiratory rate, and BI were analyzed using the two-way repeated-measures ANOVA. Results The gradual decrease in the body temperature was followed by the BI increase over time. The highest BI values (95 ± 11 Ω) appeared when the lowest values of the temperature (35.5 ± 0.5°C) were reached. The active core rewarming kept the body temperature within the physiological range (over 36.5°C). This effect was accompanied by low stable values (68 ± 3 Ω) of BI. A significant decrease over time in the hemodynamic values, respiratory rate, and shivering was seen in the active core-rewarming group when compared with the controls. The temporal course of shivering was different from those of body temperatue and BI. The control patients showed a

  2. Nuclear factor Y regulates ancient budgerigar hepadnavirus core promoter activity.

    PubMed

    Shen, Zhongliang; Liu, Yanfeng; Luo, Mengjun; Wang, Wei; Liu, Jing; Liu, Wei; Pan, Shaokun; Xie, Youhua

    2016-09-16

    Endogenous viral elements (EVE) in animal genomes are the fossil records of ancient viruses and provide invaluable information on the origin and evolution of extant viruses. Extant hepadnaviruses include avihepadnaviruses of birds and orthohepadnaviruses of mammals. The core promoter (Cp) of hepadnaviruses is vital for viral gene expression and replication. We previously identified in the budgerigar genome two EVEs that contain the full-length genome of an ancient budgerigar hepadnavirus (eBHBV1 and eBHBV2). Here, we found eBHBV1 Cp and eBHBV2 Cp were active in several human and chicken cell lines. A region from nt -85 to -11 in eBHBV1 Cp was critical for the promoter activity. Bioinformatic analysis revealed a putative binding site of nuclear factor Y (NF-Y), a ubiquitous transcription factor, at nt -64 to -50 in eBHBV1 Cp. The NF-Y core binding site (ATTGG, nt -58 to -54) was essential for eBHBV1 Cp activity. The same results were obtained with eBHBV2 Cp and duck hepatitis B virus Cp. The subunit A of NF-Y (NF-YA) was recruited via the NF-Y core binding site to eBHBV1 Cp and upregulated the promoter activity. Finally, the NF-Y core binding site is conserved in the Cps of all the extant avihepadnaviruses but not of orthohepadnaviruses. Interestingly, a putative and functionally important NF-Y core binding site is located at nt -21 to -17 in the Cp of human hepatitis B virus. In conclusion, our findings have pinpointed an evolutionary conserved and functionally critical NF-Y binding element in the Cps of avihepadnaviruses. PMID:27501758

  3. Role for erbin in bacterial activation of Nod2.

    PubMed

    Kufer, T A; Kremmer, E; Banks, D J; Philpott, D J

    2006-06-01

    Intracellular peptidoglycan (PG) recognition in human cells is mediated by the NACHT-LRR proteins Nod1 and Nod2. Elicitation of these proteins by PG motifs released from invasive bacteria triggers signaling events, resulting in the activation of the NF-kappaB pathway. In order to decipher the molecular components involved in Nod2 signal transduction, we set out to identify new interaction partners of Nod2 by using a yeast two-hybrid screen. Besides the known interaction partner RIP2, the screen identified the leucine-rich repeat (LRR)- and PDZ domain-containing family member Erbin as a binding partner of Nod2. Erbin showed a specific interaction with Nod2 in coimmunoprecipitation experiments with human HEK 293T cells. Immunofluorescence microscopy with a newly generated anti-Nod2 monoclonal antibody showed that Erbin and Nod2 partially colocalize in human cells. Subsequent analysis of the Erbin/Nod2 interaction revealed that the LRR of Erbin and the caspase activating and recruiting domains of Nod2 were necessary for this interaction. No significant interaction was observed with a Walker B box mutant of Nod2 or a Crohn's disease-associated frameshift mutant of Nod2, indicating that complex formation is dependent on the activity of the molecule. In addition, a change in the dynamics of the Erbin/Nod2 complex was observed during Shigella flexneri infection. Furthermore, ectopic expression of increasing amounts of Erbin or short hairpin RNA-mediated knockdown of Erbin showed a negative influence of Erbin on Nod2/muramyl-dipeptide-mediated NF-kappaB activation. These results implicate Erbin as a potential negative regulator of Nod2 and show that bacterial infection has an impact on Nod2/Erbin complex formation within cells. PMID:16714539

  4. Assembly of core helices and rapid tertiary folding of a small bacterial group I ribozyme

    PubMed Central

    Rangan, Prashanth; Masquida, Benoît; Westhof, Eric; Woodson, Sarah A.

    2003-01-01

    Compact but non-native intermediates have been implicated in the hierarchical folding of several large RNAs, but there is little information on their structure. In this article, ribonuclease and hydroxyl radical cleavage protection assays showed that base pairing of core helices stabilize a compact state of a small group I ribozyme from Azoarcus pre-tRNAile. Base pairing of the ribozyme core requires 10-fold less Mg2+ than stable tertiary interactions, indicating that assembly of helices in the catalytic core represents a distinct phase that precedes the formation of native tertiary structure. Tertiary folding occurs in <100 ms at 37°C. Such rapid folding is unprecedented among group I ribozymes and illustrates the association between structural complexity and folding time. A 3D model of the Azoarcus ribozyme was constructed by identifying homologous sequence motifs in rRNA. The model reveals distinct structural features, such as a large interface between the P4–P6 and P3–P9 domains, that may explain the unusual stability of the Azoarcus ribozyme and the cooperativity of folding. PMID:12574513

  5. THE COLD SHOULDER: EMISSION MEASURE DISTRIBUTIONS OF ACTIVE REGION CORES

    SciTech Connect

    Schmelz, J. T.; Pathak, S.

    2012-09-10

    The coronal heating mechanism for active region core loops is difficult to determine because these loops are often not resolved and cannot be studied individually. Rather, we concentrate on the 'inter-moss' areas between loop footpoints. We use observations from the Hinode EUV Imaging Spectrometer and the X-Ray Telescope to calculate the emission measure distributions of eight inter-moss areas in five different active regions. The combined data sets provide both high- and low-temperature constraints and ensure complete coverage in the temperature range appropriate for active regions. For AR 11113, the emission can be modeled with heating events that occur on timescales less than the cooling time. The loops in the core regions appear to be close to equilibrium and are consistent with steady heating. The other regions studied, however, appear to be dominated by nanoflare heating. Our results are consistent with the idea that active region age is an important parameter in determining whether steady or nanoflare heating is primarily responsible for the core emission, that is, older regions are more likely to be dominated by steady heating, while younger regions show more evidence of nanoflares.

  6. Origin and ecological selection of core and food-specific bacterial communities associated with meat and seafood spoilage

    PubMed Central

    Chaillou, Stéphane; Chaulot-Talmon, Aurélie; Caekebeke, Hélène; Cardinal, Mireille; Christieans, Souad; Denis, Catherine; Hélène Desmonts, Marie; Dousset, Xavier; Feurer, Carole; Hamon, Erwann; Joffraud, Jean-Jacques; La Carbona, Stéphanie; Leroi, Françoise; Leroy, Sabine; Lorre, Sylvie; Macé, Sabrina; Pilet, Marie-France; Prévost, Hervé; Rivollier, Marina; Roux, Dephine; Talon, Régine; Zagorec, Monique; Champomier-Vergès, Marie-Christine

    2015-01-01

    The microbial spoilage of meat and seafood products with short shelf lives is responsible for a significant amount of food waste. Food spoilage is a very heterogeneous process, involving the growth of various, poorly characterized bacterial communities. In this study, we conducted 16S ribosomal RNA gene pyrosequencing on 160 samples of fresh and spoiled foods to comparatively explore the bacterial communities associated with four meat products and four seafood products that are among the most consumed food items in Europe. We show that fresh products are contaminated in part by a microbiota similar to that found on the skin and in the gut of animals. However, this animal-derived microbiota was less prevalent and less abundant than a core microbiota, psychrotrophic in nature, mainly originated from the environment (water reservoirs). We clearly show that this core community found on meat and seafood products is the main reservoir of spoilage bacteria. We also show that storage conditions exert strong selective pressure on the initial microbiota: alpha diversity in fresh samples was 189±58 operational taxonomic units (OTUs) but dropped to 27±12 OTUs in spoiled samples. The OTU assemblage associated with spoilage was shaped by low storage temperatures, packaging and the nutritional value of the food matrix itself. These factors presumably act in tandem without any hierarchical pattern. Most notably, we were also able to identify putative new clades of dominant, previously undescribed bacteria occurring on spoiled seafood, a finding that emphasizes the importance of using culture-independent methods when studying food microbiota. PMID:25333463

  7. Origin and ecological selection of core and food-specific bacterial communities associated with meat and seafood spoilage.

    PubMed

    Chaillou, Stéphane; Chaulot-Talmon, Aurélie; Caekebeke, Hélène; Cardinal, Mireille; Christieans, Souad; Denis, Catherine; Desmonts, Marie Hélène; Dousset, Xavier; Feurer, Carole; Hamon, Erwann; Joffraud, Jean-Jacques; La Carbona, Stéphanie; Leroi, Françoise; Leroy, Sabine; Lorre, Sylvie; Macé, Sabrina; Pilet, Marie-France; Prévost, Hervé; Rivollier, Marina; Roux, Dephine; Talon, Régine; Zagorec, Monique; Champomier-Vergès, Marie-Christine

    2015-05-01

    The microbial spoilage of meat and seafood products with short shelf lives is responsible for a significant amount of food waste. Food spoilage is a very heterogeneous process, involving the growth of various, poorly characterized bacterial communities. In this study, we conducted 16S ribosomal RNA gene pyrosequencing on 160 samples of fresh and spoiled foods to comparatively explore the bacterial communities associated with four meat products and four seafood products that are among the most consumed food items in Europe. We show that fresh products are contaminated in part by a microbiota similar to that found on the skin and in the gut of animals. However, this animal-derived microbiota was less prevalent and less abundant than a core microbiota, psychrotrophic in nature, mainly originated from the environment (water reservoirs). We clearly show that this core community found on meat and seafood products is the main reservoir of spoilage bacteria. We also show that storage conditions exert strong selective pressure on the initial microbiota: alpha diversity in fresh samples was 189±58 operational taxonomic units (OTUs) but dropped to 27±12 OTUs in spoiled samples. The OTU assemblage associated with spoilage was shaped by low storage temperatures, packaging and the nutritional value of the food matrix itself. These factors presumably act in tandem without any hierarchical pattern. Most notably, we were also able to identify putative new clades of dominant, previously undescribed bacteria occurring on spoiled seafood, a finding that emphasizes the importance of using culture-independent methods when studying food microbiota. PMID:25333463

  8. Simultaneous transport of two bacterial strains in intact cores from Oyster, Virginia: biological effects and numerical modeling.

    PubMed

    Dong, Hailiang; Rothmel, Randi; Onstott, Tullis C; Fuller, Mark E; DeFlaun, Mary F; Streger, Sheryl H; Dunlap, Robb; Fletcher, Madilyn

    2002-05-01

    The transport characteristics of two adhesion-deficient, indigenous groundwater strains, Comamonas sp. strain DA001 and Erwinia herbicola OYS2-A, were studied by using intact sediment cores (7 by 50 cm) from Oyster, Va. Both strains are gram-negative rods (1.10 by 0.56 and 1.56 by 0.46 microm, respectively) with strongly hydrophilic membranes and a slightly negative surface charge. The two strains exhibited markedly different behaviors when they were transported through granular porous sediment. To eliminate any effects of physical and chemical heterogeneity on bacterial transport and thus isolate the biological effect, the two strains were simultaneously injected into the same core. DA001 cells were metabolically labeled with (35)S and tagged with a vital fluorescent stain, while OYS2-A cells were metabolically labeled with (14)C. The fast decay of (35)S allowed deconvolution of the two isotopes (and therefore the two strains). Dramatic differences in the transport behaviors were observed. The breakthrough of DA001 and the breakthrough of OYS2-A both occurred before the breakthrough of a conservative tracer (termed differential advection), with effluent recoveries of 55 and 30%, respectively. The retained bacterial concentration of OYS2-A in the sediment was twofold higher than that of DA001. Among the cell properties analyzed, the statistically significant differences between the two strains were cell length and diameter. The shorter, larger-diameter DA001 cells displayed a higher effluent recovery than the longer, smaller-diameter OYS2-A cells. CXTFIT modeling results indicated that compared to the DA001 cells, the OYS2-A cells experienced lower pore velocity, higher porosity, a higher attachment rate, and a lower detachment rate. All these factors may contribute to the observed differences in transport. PMID:11976080

  9. Heating of active region cores: Impulsive or steady?

    NASA Astrophysics Data System (ADS)

    Tripathi, Durgesh

    The question of active region heating has proven to be highly challenging since its discovery in 1940s. The recent observational facilities have shed new lights towards the understanding of this problem. In this paper we review some of the new measurements to study the heating mechanisms in the hot core loops of active regions using the observations recorded by Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard SoHO and the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard Hinode. These new measurements show that the properties of hot core loops are consistent with by impulsive heating -- low frequency nanoflare - scenario. However, the evidences are not strong enough to rule-out steady heating completely. Further measurement using better spectral resolution and temperature coverage is required, which will be provided by Interface Region Imaging Spectrometer (IRIS) and Solar-C in near future.

  10. Robustness of nuclear core activity reconstruction by data assimilation

    NASA Astrophysics Data System (ADS)

    Bouriquet, Bertrand; Argaud, Jean-Philippe; Erhard, Patrick; Massart, Sébastien; Ponçot, Angélique; Ricci, Sophie; Thual, Olivier

    2011-02-01

    We apply a data assimilation technique, inspired from meteorological applications, to perform an optimal reconstruction of the neutronic activity field in a nuclear core. Both measurements and information coming from a numerical model are used. We first study the robustness of the method when the amount of measured information decreases. We then study the influence of the nature of the instruments and their spatial repartition on the efficiency of the field reconstruction.

  11. Active Marine Subsurface Bacterial Population Composition in Low Organic Carbon Environments from IODP Expedition 320

    NASA Astrophysics Data System (ADS)

    Shepard, A.; Reese, B. K.; Mills, H. J.; IODP Expedition 320 Shipboard Science Party

    2011-12-01

    The marine subsurface environment contains abundant and active microorganisms. These microbial populations are considered integral players in the marine subsurface biogeochemical system with significance in global geochemical cycles and reservoirs. However, variations in microbial community structure, activity and function associated with the wide-ranging sedimentary and geochemical environments found globally have not been fully resolved. Integrated Ocean Drilling Program Expedition 320 recovered sediments from site U1332. Two sampling depths were selected for analysis that spanned differing lithological units in the sediment core. Sediments were composed of mostly clay with zeolite minerals at 8 meters below sea floor (mbsf). At 27 mbsf, sediments were composed of alternating clayey radiolarian ooze and nannofossil ooze. The concentration of SO42- had little variability throughout the core and the concentration of Fe2+ remained close to, or below, detection limits (0.4 μM). Total organic carbon content ranged from a low of 0.03 wt% to a high of 0.07 wt% between 6 and 30 mbsf providing an opportunity to evaluate marine subsurface microbial communities under extreme electron donor limiting conditions. The metabolically active fraction of the bacterial population was isolated by the extraction and amplification of 16S ribosomal RNA. Pyrosequencing of 16S rRNA transcripts and subsequent bioinformatic analyses provided a robust data set (15,931 total classified sequences) to characterize the community at a high resolution. As observed in other subsurface environments, the overall diversity of active bacterial populations decreased with depth. The population shifted from a diverse but evenly distributed community at approximately 8 mbsf to a Firmicutes dominated population at 27 mbsf (80% of sequences). A total of 95% of the sequences at 27 mbsf were grouped into three genera: Lactobacillus (phylum Firmicutes) at 80% of the total sequences, Marinobacter (phylum

  12. Potential core species and satellite species in the bacterial community within the rabbit caecum

    PubMed Central

    Monteils, Valérie; Cauquil, Laurent; Combes, Sylvie; Godon, Jean-Jacques; Gidenne, Thierry

    2008-01-01

    A bacteria library was constructed from the caecum of a rabbit maintained under standard conditions. The complete gene 16S rRNA gene was sequenced. The 228 clones obtained were distributed in 70 operational taxonomic units (OTUs). The large majority of the OTUs were composed of one or two clones and seven OTUs contained half of the sequences. Fourteen sequences had high similarity to the sequence already registered in databases (threshold of 97%). Only one of these sequences has been identified as Variovorax sp. (99% identity). Units were distributed mainly (94%) in the Firmicutes phylum. Three sequences were related to Bacteroidetes. Nine clusters were defined in the phylogenic tree. A great diversity of caecal bacteria of the rabbit was shown. Half of the sequences generated in this library were distributed in the phylogenetic tree near the sequences characterized previously in rabbit caecum (potential core species), and the other half of the sequences were well separated (satellite species). PMID:19049656

  13. Metatranscriptomic Analysis of Groundwater Reveals an Active Anammox Bacterial Population

    NASA Astrophysics Data System (ADS)

    Jewell, T. N. M.; Karaoz, U.; Thomas, B. C.; Banfield, J. F.; Brodie, E.; Williams, K. H.; Beller, H. R.

    2014-12-01

    Groundwater is a major natural resource, yet little is known about the contribution of microbial anaerobic ammonium oxidation (anammox) activity to subsurface nitrogen cycling. During anammox, energy is generated as ammonium is oxidized under anaerobic conditions to dinitrogen gas, using nitrite as the final electron acceptor. This process is a global sink for fixed nitrogen. Only a narrow range of monophyletic bacteria within the Planctomycetes carries out anammox, and the full extent of their metabolism, and subsequent impact on nitrogen cycling and microbial community structure, is still unknown. Here, we employ a metatranscriptomic analysis on enriched mRNA to identify the abundance and activity of a population of anammox bacteria within an aquifer at Rifle, CO. Planktonic biomass was collected over a two-month period after injection of up to 1.5 mM nitrate. Illumina-generated sequences were mapped to a phylogenetically binned Rifle metagenome database. We identified transcripts for genes with high protein sequence identities (81-98%) to those of anammox strain KSU-1 and to two of the five anammox bacteria genera, Brocadia and Kuenenia, suggesting an active, if not diverse, anammox population. Many of the most abundant anammox transcripts mapped to a single scaffold, indicative of a single dominant anammox species. Transcripts of the genes necessary for the anammox pathway were present, including an ammonium transporter (amtB), nitrite/formate transporter, nitrite reductase (nirK), and hydrazine oxidoreductase (hzoB). The form of nitrite reductase encoded by anammox is species-dependent, and we only identified nirK, with no evidence of anammox nirS. In addition to the anammox pathway we saw evidence of the anammox bacterial dissimilatory nitrate reduction to ammonium pathway (narH, putative nrfA, and nrfB), which provides an alternate means of generating substrates for anammox from nitrate, rather than relying on an external pool. Transcripts for hydroxylamine

  14. Bacterial communities and enzyme activities of PAHs polluted soils.

    PubMed

    Andreoni, V; Cavalca, L; Rao, M A; Nocerino, G; Bernasconi, S; Dell'Amico, E; Colombo, M; Gianfreda, L

    2004-11-01

    Three soils (i.e. a Belgian soil, B-BT, a German soil, G, and an Italian agricultural soil, I-BT) with different properties and hydrocarbon-pollution history with regard to their potential to degrade phenanthrene were investigated. A chemical and microbiological evaluation of soils was done using measurements of routine chemical properties, bacterial counts and several enzyme activities. The three soils showed different levels of polycyclic aromatic hydrocarbons (PAHs), being their contamination strictly associated to their pollution history. High values of enzyme activities and culturable heterotrophic bacteria were detected in the soil with no or negligible presence of organic pollutants. Genetic diversity of soil samples and enrichment cultures was measured as bands on denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA sequences from the soil and enrichment community DNAs. When analysed by Shannon index (H'), the highest genetic biodiversity (H'=2.87) was found in the Belgian soil B-BT with a medium-term exposition to PAHs and the poorest biodiversity (H'=0.85) in the German soil with a long-term exposition to alkanes and PAHs and where absence, or lower levels of enzyme activities were measured. For the Italian agricultural soil I-BT, containing negligible amounts of organic pollutants but the highest Cu content, a Shannon index=2.13 was found. The enrichment of four mixed cultures capable of degrading solid phenanthrene in batch liquid systems was also studied. Phenanthrene degradation rates in batch systems were culture-dependent, and simple (one-slope) and complex (two-slope) kinetic behaviours were observed. The presence of common bands of microbial species in the cultures and in the native soil DNA indicated that those strains could be potential in situ phenanthrene degraders. Consistent with this assumption are the decrease of PAH and phenanthrene contents of Belgian soil B-BT and the isolation of phenanthrene-degrading bacteria. From

  15. Extracellular enzyme activity in anaerobic bacterial cultures: evidence of pullulanase activity among mesophilic marine bacteria.

    PubMed

    Arnosti, C; Repeta, D J

    1994-03-01

    The extracellular enzymatic activity of a mixed culture of anaerobic marine bacteria enriched on pullulan [alpha(1,6)-linked maltotriose units] was directly assessed with a combination of gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy (NMR). Hydrolysis products of pullulan were separated by GPC into three fractions with molecular weights of > or = 10,000, approximately 5,000, and < or = 1,200. NMR spectra of these fractions demonstrated that pullulan was rapidly and specifically hydrolyzed at alpha(1,6) linkages by pullulanase enzymes, most likely type II pullulanase. Although isolated pullulanase enzymes have been shown to hydrolyze pullulan completely to maltotriose (S. H. Brown, H. R. Costantino, and R. M. Kelly, Appl. Environ. Microbiol. 56:1985-1991, 1990; M. Klingeberg, H. Hippe, and G. Antranikian, FEMS Microbiol. Lett. 69:145-152, 1990; R. Koch, P. Zablowski, A. Spreinat, and G. Antranikian, FEMS Microbiol. Lett. 71:21-26, 1990), the smallest carbohydrate detected in the bacterial cultures consisted of two maltotriose units linked through one alpha(1,6) linkage. Either the final hydrolysis step was closely linked to substrate uptake, or specialized porins similar to maltoporin might permit direct transport of large oligosaccharides into the bacterial cell. This is the first report of pullulanase activity among mesophilic marine bacteria. The combination of GPC and NMR could easily be used to assess other types of extracellular enzyme activity in bacterial cultures. PMID:8161177

  16. Grazing activity and ruminal bacterial population associated with frothy bloat in steers grazing winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two grazing experiments were designed to elucidate the shifts in rumen bacterial populations (Exp. 1) and grazing activities (Exp. 2) in wheat forage diets between bloated and non-bloated steers. In Exp. 1, the bacterial DNA density was greatest for Ruminococcus flavefaciens, Streptococcus bovis, a...

  17. Coevolved Mutations Reveal Distinct Architectures for Two Core Proteins in the Bacterial Flagellar Motor

    PubMed Central

    Pandini, Alessandro; Kleinjung, Jens; Rasool, Shafqat; Khan, Shahid

    2015-01-01

    Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC) “torque” helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM) domains (amino-terminal (FliGN), middle (FliGM) and FliGC) as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM) has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6). FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C) and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM-C could

  18. Emission Measure Distribution and Heating of Two Active Region Cores

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2011-01-01

    Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM/T(exp 2.4) from log T = 5.55 up to a peak at log T = 6.57. The observations are explained extremely well by a simple nanoflare model. However, in the absence of additional constraints, the observations could possibly also be explained by steady heating.

  19. Improved microbial growth inhibition activity of bio-surfactant induced Ag-TiO2 core shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Nithyadevi, D.; Kumar, P. Suresh; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.; Meena, P.

    2015-02-01

    Surfactant induced silver-titanium dioxide core shell nanoparticles within the size range of 10-50 nm were applied in the antibacterial agent to inhibit the growth of bacterial cells. The single crystalline silver was located in the core part of the composite powder and the titanium dioxide components were uniformly distributed in the shell part. HRTEM and XRD results indicated that silver was completely covered by titanium dioxide and its crystal structure was not affected after being coated by titanium dioxide. The effect of silver-titanium dioxide nanoparticles in the inhibition of bacterial cell growth was studied by means of disk diffusion method. The inhibition zone results reveal that sodium alginate induced silver-titanium dioxide nanoparticles exhibit 100% more antibacterial activity than that with cetyltrimethylbromide or without surfactant. UV-vis spectroscopic analysis showed a large concentration of silver was rapidly released into phosphate buffer solution (PBS) within a period of 1 day, with a much smaller concentration being released after this 1-day period. It was concluded that sodium alginate induced silver-titanium dioxide core shell nanoparticles could enhance long term cell growth inhibition in comparison with cetyltrimethylbromide or without surfactant. The surfactant mediated core shell nanoparticles have comparatively rapid, less expensive and wider applications in modern antibacterial therapy.

  20. 454 Pyrosequencing reveals bacterial diversity of activated sludge from 14 sewage treatment plants

    PubMed Central

    Zhang, Tong; Shao, Ming-Fei; Ye, Lin

    2012-01-01

    Activated sludge (AS) contains highly complex microbial communities. In this study, PCR-based 454 pyrosequencing was applied to investigate the bacterial communities of AS samples from 14 sewage treatment plants of Asia (mainland China, Hong Kong, and Singapore), and North America (Canada and the United States). A total of 259 K effective sequences of 16S rRNA gene V4 region were obtained from these AS samples. These sequences revealed huge amount of operational taxonomic units (OTUs) in AS, that is, 1183–3567 OTUs in a sludge sample, at 3% cutoff level and sequencing depth of 16 489 sequences. Clear geographical differences among the AS samples from Asia and North America were revealed by (1) cluster analyses based on abundances of OTUs or the genus/family/order assigned by Ribosomal Database Project (RDP) and (2) the principal coordinate analyses based on OTUs abundances, RDP taxa abundances and UniFrac of OTUs and their distances. In addition to certain unique bacterial populations in each AS sample, some genera were dominant, and core populations shared by multiple samples, including two commonly reported genera of Zoogloea and Dechloromonas, three genera not frequently reported (i.e., Prosthecobacter, Caldilinea and Tricoccus) and three genera not well described so far (i.e., Gp4 and Gp6 in Acidobacteria and Subdivision3 genera incertae sedis of Verrucomicrobia). Pyrosequencing analyses of multiple AS samples in this study also revealed the minority populations that are hard to be explored by traditional molecular methods and showed that a large proportion of sequences could not be assigned to taxonomic affiliations even at the phylum/class levels. PMID:22170428

  1. S9-DEPENDENT ACTIVATION OF 1-NITROPYRENE AND 3-NITROFLUORANTHENE IN BACTERIAL MUTAGENICITY ASSAYS

    EPA Science Inventory

    Nitro-substituted polycyclic aromatic hydrocarbons (N02PAH) such as 1-nitropyrene (NP) and 3-nitrofluoranthene (3-NFA), both widespread environmental mutagens, generally require activation by bacterial nitroreductases for maximal expression of their mutagenicity in the Ames Salmo...

  2. Effect of flow and active mixing on bacterial growth in a colon-like geometry

    NASA Astrophysics Data System (ADS)

    Cremer, Jonas; Segota, Igor; Arnoldini, Markus; Groisman, Alex; Hwa, Terence

    The large intestine harbors bacteria from hundreds of species, with bacterial densities reaching up to 1012 cells per gram. Many different factors influence bacterial growth dynamics and thus bacterial density and microbiota composition. One dominant force is flow which can in principle lead to a washout of bacteria from the proximal colon. Active mixing by Contractions of the colonic wall together with bacterial growth might counteract such flow-forces and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate Contractions. We investigate growth along the channel under a steady nutrient inflow. In the limits of no or very frequent Contractions, the device behaves like a plug-flow reactor and a chemostat respectively. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term.

  3. All-atom structures and calcium binding sites of the bacterial photosynthetic LH1-RC core complex from Thermochromatium tepidum.

    PubMed

    Khrenova, Maria G; Nemukhin, Alexander V; Grigorenko, Bella L; Wang, Peng; Zhang, Jian-Ping

    2014-06-01

    Computationally derived structures of the photosynthetic core complex composed of the light-harvesting (LH) system LH1 and the reaction center (RC) from a thermophilic purple sulfur bacterium Thermochromatium tepidum are reported providing first models of the LH1 system at atomic resolution. We used the known primary structure of α and β polypeptides from this particular LH1 complex and the related bacterial LH templates to design the LH1 torus composed of 16 αβ subunits trapping bacteriochlorophyll (BChl-a) dimers and carotenoid molecules. The macromolecule of RC was placed in the center of the ring and the LH1-RC complex was inserted inside the lipid bilayer to simulate the membrane environment. Since thermal stability of the LH1-RC complex is linked to Ca(2+) binding by the complex, location of trapping sites of calcium ions in the LH1 polypeptides is examined by using molecular dynamics simulations of the entire system solvated in water with CaCl2 molecules in the system. The newly predicted Ca(2+) trapping sites can be responsible for attractive interaction of neighboring αβ subunits of LH1 with relevance to stability of the calcium-bound LH1-RC complex. PMID:24852455

  4. Nucleus accumbens core lesions enhance two-way active avoidance.

    PubMed

    Lichtenberg, N T; Kashtelyan, V; Burton, A C; Bissonette, G B; Roesch, M R

    2014-01-31

    The majority of work examining the nucleus accumbens core (NAc) has focused on functions pertaining to behaviors guided by appetitive outcomes. These studies have pointed to the NAc as being critical for motivating behavior toward desirable outcomes. For example, we have recently shown that lesions of the NAc impaired performance on a reward-guided decision-making task that required rats to choose between differently valued rewards. Unfortunately, much less is known about the role that the NAc plays in motivating behavior when aversive outcomes are predicted. To address this issue we asked if NAc lesions impact performance on a two-way active avoidance task in which rats must learn to shuttle back and forth in a behavioral training box in order to avoid a footshock predicted by an auditory tone. Although bilateral NAc lesions initially impaired reward-guided decision-making, we found that the same lesions improved acquisition and retention of two-way active avoidance. PMID:24275320

  5. Therapeutic activity of modified U1 core spliceosomal particles

    PubMed Central

    Rogalska, Malgorzata Ewa; Tajnik, Mojca; Licastro, Danilo; Bussani, Erica; Camparini, Luca; Mattioli, Chiara; Pagani, Franco

    2016-01-01

    Modified U1 snRNAs bound to intronic sequences downstream of the 5′ splice site correct exon skipping caused by different types of mutations. Here we evaluate the therapeutic activity and structural requirements of these exon-specific U1 snRNA (ExSpeU1) particles. In a severe spinal muscular atrophy, mouse model, ExSpeU1, introduced by germline transgenesis, increases SMN2 exon 7 inclusion, SMN protein production and extends life span. In vitro, RNA mutant analysis and silencing experiments show that while U1A protein is dispensable, the 70K and stem loop IV elements mediate most of the splicing rescue activity through improvement of exon and intron definition. Our findings indicate that precise engineering of the U1 core spliceosomal RNA particle has therapeutic potential in pathologies associated with exon-skipping mutations. PMID:27041075

  6. Therapeutic activity of modified U1 core spliceosomal particles.

    PubMed

    Rogalska, Malgorzata Ewa; Tajnik, Mojca; Licastro, Danilo; Bussani, Erica; Camparini, Luca; Mattioli, Chiara; Pagani, Franco

    2016-01-01

    Modified U1 snRNAs bound to intronic sequences downstream of the 5' splice site correct exon skipping caused by different types of mutations. Here we evaluate the therapeutic activity and structural requirements of these exon-specific U1 snRNA (ExSpeU1) particles. In a severe spinal muscular atrophy, mouse model, ExSpeU1, introduced by germline transgenesis, increases SMN2 exon 7 inclusion, SMN protein production and extends life span. In vitro, RNA mutant analysis and silencing experiments show that while U1A protein is dispensable, the 70K and stem loop IV elements mediate most of the splicing rescue activity through improvement of exon and intron definition. Our findings indicate that precise engineering of the U1 core spliceosomal RNA particle has therapeutic potential in pathologies associated with exon-skipping mutations. PMID:27041075

  7. Bacterial diversity is strongly associated with historical penguin activity in an Antarctic lake sediment profile.

    PubMed

    Zhu, Renbin; Shi, Yu; Ma, Dawei; Wang, Can; Xu, Hua; Chu, Haiyan

    2015-01-01

    Current penguin activity in Antarctica affects the geochemistry of sediments and their microbial communities; the effects of historical penguin activity are less well understood. Here, bacterial diversity in ornithogenic sediment was investigated using high-throughput pyrosequencing. The relative abundances of dominant phyla were controlled by the amount of historical penguin guano deposition. Significant positive correlations were found between both the bacterial richness and diversity, and the relative penguin number (p < 0.01); this indicated that historical penguin activity drove the vertical distribution of the bacterial communities. The lowest relative abundances of individual phyla corresponded to lowest number of penguin population at 1,800-2,300 yr BP during a drier and colder period; the opposite was observed during a moister and warmer climate (1,400-1,800 yr BP). This study shows that changes in the climate over millennia affected penguin populations and the outcomes of these changes affect the sediment bacterial community today. PMID:26601753

  8. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ashraf, Sumaira; Chatha, Mariyam Asghar; Ejaz, Wardah; Janjua, Hussnain Ahmed; Hussain, Irshad

    2014-10-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests.

  9. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    PubMed Central

    2014-01-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests. PMID:25435831

  10. Seven-core active fibre for application in telecommunication satellites

    NASA Astrophysics Data System (ADS)

    Filipowicz, Marta; Napierała, Marek; Murawski, Michał; Ostrowski, Łukasz; Szostkiewicz, Łukasz; Szymański, Michał; Tenderenda, Tadeusz; Anders, Krzysztof; Piramidowicz, Ryszard; Wójcik, Grzegorz; Makara, Mariusz; Poturaj, Krzysztof; Mergo, Paweł; Nasiłowski, Tomasz

    2015-12-01

    The use of optical elements and other photonic components makes it possible to overcome telecommunication satellite's bottleneck problems such as size and weight reduction. Despite the unquestionable potential of such elements, nowadays they are not widely used in systems operating in space. This is due to many factors, including the fact that space radiation has disruptive influence on optical fibre. Namely it introduces additional radiation induced attenuation (RIA) that significantly lowers efficiency of optical fibre based systems. However, there is a possibility to produce radiation-hardened (rad-hard) components. One of them is seven core erbium-doped active fibre (MC-EDF) for fibre amplifiers in satellites that we have been developing. In this paper we present a detailed description of seven core structure design as well as experimental results. We report that average gain of 20 dB in C-band with noise figure of 5.8 dB was obtained. We also confirmed that low crosstalk value for a multicore fibre amplifier based on our fibre can be achieved.

  11. Characterization of CCN and IN activity of bacterial isolates collected in Atlanta, GA

    NASA Astrophysics Data System (ADS)

    Purdue, Sara; Waters, Samantha; Karthikeyan, Smruthi; Konstantinidis, Kostas; Nenes, Athanasios

    2016-04-01

    Characterization of CCN activity of bacteria, other than a few select types such as Pseudomonas syringae, is limited, especially when looked at in conjunction with corresponding IN activity. The link between these two points is especially important for bacteria as those that have high CCN activity are likely to form an aqueous phase required for immersion freezing. Given the high ice nucleation temperature of bacterial cells, especially in immersion mode, it is important to characterize the CCN and IN activity of many different bacterial strains. To this effect, we developed a droplet freezing assay (DFA) which consists of an aluminum cold plate, cooled by a continuous flow of an ethylene glycol-water mixture, in order to observe immersion freezing of the collected bacteria. Here, we present the initial results on the CCN and IN activities of bacterial samples we have collected in Atlanta, GA. Bacterial strains were collected and isolated from rainwater samples taken from different storms throughout the year. We then characterized the CCN activity of each strain using a DMT Continuous Flow Streamwise Thermal Gradient CCN Counter by exposing the aerosolized bacteria to supersaturations ranging from 0.05% to 0.6%. Additionally, using our new DFA, we characterized the IN activity of each bacterial strain at temperatures ranging from -20oC to 0oC. The combined CCN and IN activity gives us valuable information on how some uncharacterized bacteria contribute to warm and mixed-phase cloud formation in the atmosphere.

  12. Regulation of bacterial communities through antimicrobial activity by the coral holobiont.

    PubMed

    Kvennefors, E Charlotte E; Sampayo, Eugenia; Kerr, Caroline; Vieira, Genyess; Roff, George; Barnes, Andrew C

    2012-04-01

    Interactions between corals and associated bacteria and amongst these bacterial groups are likely to play a key role in coral health. However, the complexity of these interactions is poorly understood. We investigated the functional role of specific coral-associated bacteria in maintaining microbial communities on the coral Acropora millepora (Ehrenberg 1834) and the ability of coral mucus to support or inhibit bacterial growth. Culture-independent techniques were used to assess bacterial community structures whilst bacterial culture was employed to assess intra- and inter-specific antimicrobial activities of bacteria. Members of Pseudoalteromonas and ribotypes closely related to Vibrio coralliilyticus displayed potent antimicrobial activity against a range of other cultured isolates and grew readily on detached coral mucus. Although such bacterial ribotypes would be expected to have a competitive advantage, they were rare or absent on intact and healthy coral colonies growing in situ (analysed using denaturing gradient gel electrophoresis and 16S rRNA gene sequencing). The most abundant bacterial ribotypes found on healthy corals were Gammaproteobacteria, previously defined as type A coral associates. Our results indicate that this group of bacteria and specific members of the Alphaproteobacteria described here as 'type B associates' may be important functional groups for coral health. We suggest that bacterial communities on coral are kept in check by a combination of host-derived and microbial interactions and that the type A associates in particular may play a key role in maintaining stability of microbial communities on healthy coral colonies. PMID:21984347

  13. Electro-active hybrid actuators based on freeze-dried bacterial cellulose and PEDOT:PSS

    NASA Astrophysics Data System (ADS)

    Kim, Si-Seup; Jeon, Jin-Han; Kee, Chang-Doo; Oh, Il-Kwon

    2013-08-01

    We report a high-performance electro-active hybrid actuator based on freeze-dried bacterial cellulose and conducting polymer electrodes. The freeze-dried bacterial cellulose, which has a sponge form, can absorb a much greater amount of ionic liquid, which is a prerequisite for dry-type and high-performance electro-active polymers. In addition, the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting layers are deposited on the top and bottom surfaces of the freeze-dried bacterial cellulose using a simple dipping and drying method. The results show that the freeze-dried bacterial cellulose actuator with conducting polymer electrodes has a much larger tip displacement under electrical stimuli than pure bacterial cellulose actuators with metallic electrodes. The large bending displacement of the freeze-dried bacterial cellulose actuator under low input voltage is due to the synergistic effects of the ion migration of the dissociated ionic liquids inside the bacterial cellulose and the electrochemical doping processes of the PEDOT:PSS electrode layers.

  14. Combined Analysis of Variation in Core, Accessory and Regulatory Genome Regions Provides a Super-Resolution View into the Evolution of Bacterial Populations.

    PubMed

    McNally, Alan; Oren, Yaara; Kelly, Darren; Pascoe, Ben; Dunn, Steven; Sreecharan, Tristan; Vehkala, Minna; Välimäki, Niko; Prentice, Michael B; Ashour, Amgad; Avram, Oren; Pupko, Tal; Dobrindt, Ulrich; Literak, Ivan; Guenther, Sebastian; Schaufler, Katharina; Wieler, Lothar H; Zhiyong, Zong; Sheppard, Samuel K; McInerney, James O; Corander, Jukka

    2016-09-01

    The use of whole-genome phylogenetic analysis has revolutionized our understanding of the evolution and spread of many important bacterial pathogens due to the high resolution view it provides. However, the majority of such analyses do not consider the potential role of accessory genes when inferring evolutionary trajectories. Moreover, the recently discovered importance of the switching of gene regulatory elements suggests that an exhaustive analysis, combining information from core and accessory genes with regulatory elements could provide unparalleled detail of the evolution of a bacterial population. Here we demonstrate this principle by applying it to a worldwide multi-host sample of the important pathogenic E. coli lineage ST131. Our approach reveals the existence of multiple circulating subtypes of the major drug-resistant clade of ST131 and provides the first ever population level evidence of core genome substitutions in gene regulatory regions associated with the acquisition and maintenance of different accessory genome elements. PMID:27618184

  15. Active Heave-Compensated Coring On The New Jersey Shelf

    NASA Astrophysics Data System (ADS)

    Nielson, D. L.; Pardey, M.; Austin, J. A.; Goff, J. A.; Alexander, C.; Christensen, B. A.; Gulick, S. P.; Fulthorpe, C. S.; Nordfjord, S.; Sommerfield, C.; Venherm, C.

    2003-12-01

    The continental shelves are of obvious scientific and strategic importance. However, the ability to cost-effectively collect core samples of continental shelf sediments has been limited by technical difficulties. Many sites of scientific interest are too shallow to be drilled by large drill ships, and they are too deep to be drilled economically from jack-up platforms. DOSECC has developed an Active Heave Compensated (AHC800) drilling system under sponsorship of the Office of Naval Research to overcome these obstacles by building a small active heave compensated drilling rig that can be used to collect high-quality core from selected vessels of opportunity. The AHC800 drilling rig is designed to collect continuous core to a total drill string length of 800 m. Water depths of 200 m and less are optimal; however, with some modification operation in deeper water is possible. The AHC800 senses vessel heave using a constantly tensioned low-stretch taut line attached to a seafloor weight. A linear position transducer is attached to this taut line and through the data acquisition system, the ship's distance from the bottom is communicated to the heave compensation computer running Labview RT operating system and object-based software language. This real-time control system is used to achieve a 10-ms control loop for both data gathering and output functions. The Labview RT system continuously controls two hydraulic cylinders that keep the heave carriage and the drill string at the same reference distance from the bottom. The AHC800 system was used on the R/V Knorr on the New Jersey continental shelf in water depths from 74 to 130 m from 25 Sep to 15 Oct 2002. The AHC800 system performed up to and beyond its design specifications. The rig was designed to compensate for 2.44 m of heave with an 8 s period. However, the Knorr's response was a 6 s period resulting in a significant increase in the required acceleration as well as a faster response time for the system as a whole

  16. Bacterial Proteasome Activator Bpa (Rv3780) Is a Novel Ring-Shaped Interactor of the Mycobacterial Proteasome

    PubMed Central

    Delley, Cyrille L.; Laederach, Juerg; Ziemski, Michal; Bolten, Marcel; Boehringer, Daniel; Weber-Ban, Eilika

    2014-01-01

    The occurrence of the proteasome in bacteria is limited to the phylum of actinobacteria, where it is maintained in parallel to the usual bacterial compartmentalizing proteases. The role it plays in these organisms is still not fully understood, but in the human pathogen Mycobacterium tuberculosis (Mtb) the proteasome supports persistence in the host. In complex with the ring-shaped ATPase Mpa (called ARC in other actinobacteria), the proteasome can degrade proteins that have been post-translationally modified with the prokaryotic ubiquitin-like protein Pup. Unlike for the eukaryotic proteasome core particle, no other bacterial proteasome interactors have been identified to date. Here we describe and characterize a novel bacterial proteasome activator of Mycobacterium tuberculosis we termed Bpa (Rv3780), using a combination of biochemical and biophysical methods. Bpa features a canonical C-terminal proteasome interaction motif referred to as the HbYX motif, and its orthologs are only found in those actinobacteria encoding the proteasomal subunits. Bpa can inhibit degradation of Pup-tagged substrates in vitro by competing with Mpa for association with the proteasome. Using negative-stain electron microscopy, we show that Bpa forms a ring-shaped homooligomer that can bind coaxially to the face of the proteasome cylinder. Interestingly, Bpa can stimulate the proteasomal degradation of the model substrate β-casein, which suggests it could play a role in the removal of non-native or damaged proteins. PMID:25469515

  17. Polymer-Ag nanocomposites with enhanced antimicrobial activity against bacterial infection.

    PubMed

    Mei, Lin; Lu, Zhentan; Zhang, Xinge; Li, Chaoxing; Jia, Yanxia

    2014-09-24

    Herein, a nontoxic nanocomposite is synthesized by reduction of silver nitrate in the presence of a cationic polymer displaying strong antimicrobial activity against bacterial infection. These nanocomposites with a large concentration of positive charge promote their adsorption to bacterial membranes through electrostatic interaction. Moreover, the synthesized nanocomposites with polyvalent and synergistic antimicrobial effects can effectively kill both Gram-positive and Gram-negative bacteria without the emergence of bacterial resistance. Morphological changes obtained by transmission electron microscope observation show that these nanocomposites can cause leakage and chaos of intracellular contents. Analysis of the antimicrobial mechanism confirms that the lethal action of nanocomposites against the bacteria started with disruption of the bacterial membrane, subsequent cellular internalization of the nanoparticles, and inhibition of intracellular enzymatic activity. This novel antimicrobial material with good cytocompatibility promotes healing of infected wounds in diabetic rats, and has a promising future in the treatment of other infectious diseases. PMID:25170799

  18. EVIDENCE OF IMPULSIVE HEATING IN ACTIVE REGION CORE LOOPS

    SciTech Connect

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2010-11-01

    Using a full spectral scan of an active region from the Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained emission measure EM(T) distributions in two different moss regions within the same active region. We have compared these with theoretical transition region EMs derived for three limiting cases, namely, static equilibrium, strong condensation, and strong evaporation from Klimchuk et al. The EM distributions in both the moss regions are strikingly similar and show a monotonically increasing trend from log T[K] = 5.15-6.3. Using photospheric abundances, we obtain a consistent EM distribution for all ions. Comparing the observed and theoretical EM distributions, we find that the observed EM distribution is best explained by the strong condensation case (EM{sub con}), suggesting that a downward enthalpy flux plays an important and possibly dominant role in powering the transition region moss emission. The downflows could be due to unresolved coronal plasma that is cooling and draining after having been impulsively heated. This supports the idea that the hot loops (with temperatures of 3-5 MK) seen in the core of active regions are heated by nanoflares.

  19. Core functional traits of bacterial communities in the Upper Mississippi River show limited variation in response to land cover

    PubMed Central

    Staley, Christopher; Gould, Trevor J.; Wang, Ping; Phillips, Jane; Cotner, James B.; Sadowsky, Michael J.

    2014-01-01

    Taxonomic characterization of environmental microbial communities via high-throughput DNA sequencing has revealed that patterns in microbial biogeography affect community structure. However, shifts in functional diversity related to variation in taxonomic composition are poorly understood. To overcome limitations due to the prohibitive cost of high-depth metagenomic sequencing, tools to infer functional diversity based on phylogenetic distributions of functional traits have been developed. In this study we characterized functional microbial diversity at 11 sites along the Mississippi River in Minnesota using both metagenomic sequencing and functional-inference-based (PICRUSt) approaches. This allowed us to determine how distance and variation in land cover throughout the river influenced the distribution of functional traits, as well as to validate PICRUSt inferences. The distribution and abundance of functional traits, by metagenomic analysis, were similar among sites, with a median standard deviation of 0.0002% among tier 3 functions in KEGG. Overall inferred functional variation was significantly different (P ≤ 0.035) between two water basins surrounded by agricultural vs. developed land cover, and abundances of bacterial orders that correlated with functional traits by metagenomic analysis were greater where abundances of the trait were inferred to be higher. PICRUSt inferences were significantly correlated (r = 0.147, P = 1.80 × 10−30) with metagenomic annotations. Discrepancies between metagenomic and PICRUSt taxonomic-functional relationships, however, suggested potential functional redundancy among abundant and rare taxa that impeded the ability to accurately assess unique functional traits among rare taxa at this sequencing depth. Results of this study suggest that a suite of “core functional traits” is conserved throughout the river and distributions of functional traits, rather than specific taxa, may shift in response to environmental

  20. Regulation of bacterial metabolic activity by dissolved organic carbon and viruses

    NASA Astrophysics Data System (ADS)

    Xu, Jie; Jing, Hongmei; Sun, Mingming; Harrison, Paul J.; Liu, Hongbin

    2013-12-01

    regulation of bacterial metabolic activity by viruses and dissolved organic carbon (DOC) was examined using natural microbial communities in three treatments (active viruses, inactive viruses, and virus free) at two contrasting coastal sites (pristine vs. eutrophic) with substantial differences in environmental conditions during the wet and dry seasons. Our results showed that net growth rates and production of bacterioplankton were reduced primarily by viruses via repressing metabolically active bacteria with high nucleic acid (HNA) content which had a high capacity for incorporating carbon, while bacterial respiration was primarily regulated by DOC lability. The quality of organic matter played a more important role in regulating bacterial growth efficiency (BGE) than the supply of organic matter in eutrophic coastal waters. The lack of HMW-DOC and high carbon demand in the virus-free treatment resulted in a significant increase in cell-specific bacterial respiration, which was responsible for the lowest bacterial growth efficiency among the three treatments. The presence of viruses did not necessarily lower bacterial growth efficiency since virus-induced mortality alleviated bacterial carbon demand and enhanced carbon cycling. Virus-induced mortality was greater in relatively pristine waters than eutrophic waters, likely since the high supply of substrates alleviated the pressure of viral infection, through extracellular proteases produced by bacteria, which might result in the hydrolytic destruction or modification of viral capsids. An important implication of our results was that the input of riverine DOC and nutrients improved bacterial metabolic activity by alleviating virus-induced mortality of bacteria in estuarine and coastal waters.

  1. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

    PubMed Central

    Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.; Bælum, Jacob; Taş, Neslihan; Elberling, Bo; Jansson, Janet K.; Semenchuk, Philipp; Priemé, Anders

    2015-01-01

    The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below −10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface. PMID:25983731

  2. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

    SciTech Connect

    Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.; Bælum, Jacob; Taş, Neslihan; Elberling, Bo; Jansson, Janet K.; Semenchuk, Philipp; Priemé, Anders

    2015-04-30

    The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface.

  3. Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

    DOE PAGESBeta

    Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.; Bælum, Jacob; Taş, Neslihan; Elberling, Bo; Jansson, Janet K.; Semenchuk, Philipp; Priemé, Anders

    2015-04-30

    The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy numbermore » of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface.« less

  4. Bacterial diversity and active biomass in full-scale granular activated carbon filters operated at low water temperatures.

    PubMed

    Kaarela, Outi E; Härkki, Heli A; Palmroth, Marja R T; Tuhkanen, Tuula A

    2015-01-01

    Granular activated carbon (GAC) filtration enhances the removal of natural organic matter and micropollutants in drinking water treatment. Microbial communities in GAC filters contribute to the removal of the biodegradable part of organic matter, and thus help to control microbial regrowth in the distribution system. Our objectives were to investigate bacterial community dynamics, identify the major bacterial groups, and determine the concentration of active bacterial biomass in full-scale GAC filters treating cold (3.7-9.5°C), physicochemically pretreated, and ozonated lake water. Three sampling rounds were conducted to study six GAC filters of different operation times and flow modes in winter, spring, and summer. Total organic carbon results indicated that both the first-step and second-step filters contributed to the removal of organic matter. Length heterogeneity analysis of amplified 16S rRNA genes illustrated that bacterial communities were diverse and considerably stable over time. α-Proteobacteria, β-Proteobacteria, and Nitrospira dominated in all of the GAC filters, although the relative proportion of dominant phylogenetic groups in individual filters differed. The active bacterial biomass accumulation, measured as adenosine triphosphate, was limited due to low temperature, low flux of nutrients, and frequent backwashing. The concentration of active bacterial biomass was not affected by the moderate seasonal temperature variation. In summary, the results provided an insight into the biological component of GAC filtration in cold water temperatures and the operational parameters affecting it. PMID:25242545

  5. Mechanistic Analysis of Activation of the Innate Immune Sensor PKR by Bacterial RNA.

    PubMed

    Hull, Chelsea M; Bevilacqua, Philip C

    2015-11-01

    The protein kinase PKR (protein kinase R) is a sensor in innate immunity. PKR autophosphorylates in the presence of double-stranded RNA enabling it to phosphorylate its substrate, eIF2α (eukaryotic initiation factor 2α), halting cellular translation. Classical activators of PKR are long viral double-stranded RNAs, but recently, PKR has been found to be activated by bacterial RNA. However, the features of bacterial RNA that activate PKR are unknown. We studied the Bacillus subtilis trp 5'-UTR (untranslated region), which is an indirect riboswitch with secondary and tertiary RNA structures that regulate gene function. Additionally, the trp 5'-UTR binds a protein, TRAP (tryptophan RNA-binding attenuation protein), which recognizes l-tryptophan. We present the first evidence that multiple structural features in this RNA, which are typical of bacterial RNAs, activate PKR in TRAP-free and TRAP/l-Trp-bound forms. Segments from the 5'-UTR, including the terminator 5'-stem-loop and Shine-Dalgarno blocking hairpins, demonstrated 5'-triphosphate and flanking RNA tail dependence on PKR activation. Disruption of long-distance tertiary interactions in the 5'-UTR led to partial loss in activation, consistent with highly base-paired regions in bacterial RNA activating PKR. One physiological change a bacterial RNA would face in a human cell is a decrease in the concentration of free magnesium. Upon lowering the magnesium concentration to human physiological conditions of 0.5mM, the trp 5'-UTR continued to activate PKR potently. Moreover, total RNA from Escherichia coli, depleted of rRNA, also activated PKR under these ionic conditions. This study demonstrates that PKR can signal the presence of bacterial RNAs under physiological ionic conditions and offers a potential explanation for the apparent absence of riboswitches in the human genome. PMID:26026708

  6. Bacterial pathogens activate plasminogen to breach tissue barriers and escape from innate immunity.

    PubMed

    Peetermans, Marijke; Vanassche, Thomas; Liesenborghs, Laurens; Lijnen, Roger H; Verhamme, Peter

    2016-11-01

    Both coagulation and fibrinolysis are tightly connected with the innate immune system. Infection and inflammation cause profound alterations in the otherwise well-controlled balance between coagulation and fibrinolysis. Many pathogenic bacteria directly exploit the host's hemostatic system to increase their virulence. Here, we review the capacity of bacteria to activate plasminogen. The resulting proteolytic activity allows them to breach tissue barriers and evade innate immune defense, thus promoting bacterial spreading. Yersinia pestis, streptococci of group A, C and G and Staphylococcus aureus produce a specific bacterial plasminogen activator. Moreover, surface plasminogen receptors play an established role in pneumococcal, borrelial and group B streptococcal infections. This review summarizes the mechanisms of bacterial activation of host plasminogen and the role of the fibrinolytic system in infections caused by these pathogens. PMID:26485450

  7. DUAL ACTIVE GALACTIC NUCLEI: DEPROJECTING THE BINARY CORES

    SciTech Connect

    Wang, X.-W.; Zhou, H.-Y.

    2012-10-01

    Dual active galactic nuclei (AGNs) as a population in a special phase during the evolution of merging galaxies have been found largely from candidates selected from the Sloan Digital Sky Survey (SDSS). In this paper, we develop a simple model of dual AGNs, which are composed of two optically thin spheres emitting narrow lines and co-rotating governed by gravity between them. In order to show how profiles are sensitive to the orientation angles of the orbiting plane and phase angles, we make detailed calculations of profiles for a large space of the two angles. The dual AGNs observationally appear as ones with double-peaked profiles of emission lines, but there are still quite large ranges of orientation and phase angles where they appear only with a single-peaked profile. This implies a large fraction of dual AGN candidate missed by selecting AGNs with double-peaked profiles. We show that the highly sensitive dependence of profiles on orientation and phase angles makes them robust to deproject dual AGN systems. Deprojection by the present model has potential implications for discussion of the triggering mechanism of black hole activity in light of the deprojected distance. We apply the present model to two dual AGN, SDSS J095207.6+255257 and J171544.05+600835.7, for deprojection of the binary cores.

  8. Prodigiosin inhibits motility and activates bacterial cell death revealing molecular biomarkers of programmed cell death.

    PubMed

    Darshan, N; Manonmani, H K

    2016-12-01

    The antimicrobial activity of prodigiosin from Serratia nematodiphila darsh1, a bacterial pigment was tested against few food borne bacterial pathogens Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The mode of action of prodigiosin was studied. Prodigiosin induced bactericidal activity indicating a stereotypical set of biochemical and morphological feature of Programmed cell death (PCD). PCD involves DNA fragmentation, generation of ROS, and expression of a protein with caspase-like substrate specificity in bacterial cells. Prodigiosin was observed to be internalized into bacterial cells and was localized predominantly in the membrane and the nuclear fraction, thus, facilitating intracellular trafficking and then binding of prodigiosin to the bacterial DNA. Corresponding to an increasing concentration of prodigiosin, the level of certain proteases were observed to increase in bacteria studied, thus initiating the onset of PCD. Prodigiosin at a sub-inhibitory concentration inhibits motility of pathogens. Our observations indicated that prodigiosin could be a promising antibacterial agent and could be used in the prevention of bacterial infections. PMID:27460563

  9. Active viscoelastic matter: from bacterial drag reduction to turbulent solids.

    PubMed

    Hemingway, E J; Maitra, A; Banerjee, S; Marchetti, M C; Ramaswamy, S; Fielding, S M; Cates, M E

    2015-03-01

    A paradigm for internally driven matter is the active nematic liquid crystal, whereby the equations of a conventional nematic are supplemented by a minimal active stress that violates time-reversal symmetry. In practice, active fluids may have not only liquid-crystalline but also viscoelastic polymer degrees of freedom. Here we explore the resulting interplay by coupling an active nematic to a minimal model of polymer rheology. We find that adding a polymer can greatly increase the complexity of spontaneous flow, but can also have calming effects, thereby increasing the net throughput of spontaneous flow along a pipe (a "drag-reduction" effect). Remarkably, active turbulence can also arise after switching on activity in a sufficiently soft elastomeric solid. PMID:25793858

  10. Predicting Activation of Experiments Inside the Annular Core Research Reactor

    SciTech Connect

    Greenberg, Joseph Isaac

    2015-11-01

    The objective of this thesis is to create a program to quickly estimate the radioactivity and decay of experiments conducted inside of the Annular Core Research Reactor at Sandia National Laboratories and eliminate the need for users to write code. This is achieved by model the neutron fluxes in the reactor’s central cavity where experiments are conducted for 4 different neutron spectra using MCNP. The desired neutron spectrum, experiment material composition, and reactor power level are then input into CINDER2008 burnup code to obtain activation and decay information for every isotope generated. DREAD creates all of the files required for CINDER2008 through user selected inputs in a graphical user interface and executes the program for the user and displays the resulting estimation for dose rate at various distances. The DREAD program was validated by weighing and measuring various experiments in the different spectra and then collecting dose rate information after they were irradiated and comparing it to the dose rates that DREAD predicted. The program provides results with an average of 17% higher estimates than the actual values and takes seconds to execute.

  11. In Vitro Activity of Gepotidacin, a Novel Triazaacenaphthylene Bacterial Topoisomerase Inhibitor, against a Broad Spectrum of Bacterial Pathogens.

    PubMed

    Biedenbach, D J; Bouchillon, S K; Hackel, M; Miller, L A; Scangarella-Oman, N E; Jakielaszek, C; Sahm, D F

    2016-01-01

    Gepotidacin inhibits bacterial DNA replication through a mode different from that of fluoroquinolones. Gepotidacin and comparators were tested by broth and agar dilution against clinical isolates. The in vitro activities of gepotidacin were comparable against methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA, respectively) isolates (MIC90, 0.5 μg/ml). The gepotidacin MIC90s were as follows (in micrograms per milliliter) for the indicated bacteria: Streptococcus pyogenes, 0.25; Escherichia coli, 2; Moraxella catarrhalis, ≤0.06; Streptococcus pneumoniae (0.25), Haemophilus influenzae, 1; Clostridium perfringens, 0.5; and Shigella spp., 1, including levofloxacin-resistant subsets. Gepotidacin warrants further investigation for clinical development. PMID:26729499

  12. Differences in activity profile of bacterial cultures studied by dynamic speckle patterns

    NASA Astrophysics Data System (ADS)

    Ramírez-Miquet, E. E.; Otero, I.; Rodríguez, D.; Darias, J. G.; Combarro, A. M.; Contreras, O. R.

    2013-02-01

    We outline the main differences in the activity profile of bacterial cultures studied by dynamic laser speckle (or biospeckle) patterns. The activity is detected in two sorts of culture mediums. The optical setup and the experimental procedure are presented. The experimentally obtained images are processed by the temporal difference method and a qualitative assessment is made with the time history of speckle patterns of the sample. The main differences are studied after changing the culture medium composition. We conclude that the EC medium is suitable to detect the E. coli bacterial presence in early hours and that Mueller Hinton agar delays some additional hours to make possible the assessment of bacteria in time.

  13. Active bacterial community structure along vertical redox gradients in Baltic Sea sediment

    SciTech Connect

    Jansson, Janet; Edlund, Anna; Hardeman, Fredrik; Jansson, Janet K.; Sjoling, Sara

    2008-05-15

    Community structures of active bacterial populations were investigated along a vertical redox profile in coastal Baltic Sea sediments by terminal-restriction fragment length polymorphism (T-RFLP) and clone library analysis. According to correspondence analysis of T-RFLP results and sequencing of cloned 16S rRNA genes, the microbial community structures at three redox depths (179 mV, -64 mV and -337 mV) differed significantly. The bacterial communities in the community DNA differed from those in bromodeoxyuridine (BrdU)-labeled DNA, indicating that the growing members of the community that incorporated BrdU were not necessarily the most dominant members. The structures of the actively growing bacterial communities were most strongly correlated to organic carbon followed by total nitrogen and redox potentials. Bacterial identification by sequencing of 16S rRNA genes from clones of BrdU-labeled DNA and DNA from reverse transcription PCR (rt-PCR) showed that bacterial taxa involved in nitrogen and sulfur cycling were metabolically active along the redox profiles. Several sequences had low similarities to previously detected sequences indicating that novel lineages of bacteria are present in Baltic Sea sediments. Also, a high number of different 16S rRNA gene sequences representing different phyla were detected at all sampling depths.

  14. Anaerobic ammonium oxidation (anammox) bacterial diversity, abundance, and activity in marsh sediments of the Yangtze Estuary

    NASA Astrophysics Data System (ADS)

    Hou, Lijun; Zheng, Yanling; Liu, Min; Gong, Jun; Zhang, Xiaoli; Yin, Guoyu; You, Li

    2013-07-01

    ammonium oxidation (anammox) as an important process of nitrogen cycle has been studied in estuarine environments. However, knowledge about the dynamics of anammox bacteria and their interactions with associated activity remains scarce in these environments. Here we report the anammox bacterial diversity, abundance, and activity in the Yangtze Estuary, using molecular and isotope-tracing techniques. The phylogenetic analysis of 16S rRNA indicated that high anammox bacterial diversity occurred in this estuary, including Scalindua, Brocadia, Kuenenia, and two novel clusters. The patterns of community composition and diversity of anammox bacteria differed across the estuary. Salinity was a key environmental factor defining the geographical distribution and diversity of the anammox bacterial community at the estuarine ecosystem. Temperature and organic carbon also had significant influences on anammox bacterial biodiversity. The abundance of anammox bacteria ranged from 2.63 × 106 and 1.56 × 107 gene copies g-1, and its spatiotemporal variations were related significantly to salinity, temperature, and nitrite content. The anammox activity was related to temperature, nitrite, and anammox bacterial abundance, with values of 0.94-6.61 nmol N g-1 h-1. The tight link between the anammox and denitrification processes implied that denitrifying bacteria may be a primary source of nitrite for the anammox bacteria in the estuarine marshes. On the basis of the 15N tracing experiments, the anammox process was estimated to contribute 6.6%-12.9% to the total nitrogen loss whereas the remainder was attributed to denitrification.

  15. Effect of Condensed Tannins on Bacterial Diversity and Metabolic Activity in the Rat Gastrointestinal Tract

    PubMed Central

    Smith, Alexandra H.; Mackie, Roderick I.

    2004-01-01

    The effect of dietary condensed tannins (proanthocyanidins) on rat fecal bacterial populations was ascertained in order to determine whether the proportion on tannin-resistant bacteria increased and if there was a change in the predominant bacterial populations. After 3 weeks of tannin diets the proportion of tannin-resistant bacteria increased significantly (P < 0.05) from 0.3% ± 5.5% to 25.3% ± 8.3% with a 0.7% tannin diet and to 47.2% ± 5.1% with a 2% tannin diet. The proportion of tannin-resistant bacteria returned to preexposure levels in the absence of dietary tannins. A shift in bacterial populations was confirmed by molecular fingerprinting of fecal bacterial populations by denaturing gradient gel electrophoresis (DGGE). Posttreatment samples were generally still distinguishable from controls after 3.5 weeks. Sequence analysis of DGGE bands and characterization of tannin-resistant isolates indicated that tannins selected for Enterobacteriaceae and Bacteroides species. Dot blot quantification confirmed that these gram-negative bacterial groups predominated in the presence of dietary tannins and that there was a corresponding decrease in the gram-positive Clostridium leptum group and other groups. Metabolic fingerprint patterns revealed that functional activities of culturable fecal bacteria were affected by the presence of tannins. Condensed tannins of Acacia angustissima altered fecal bacterial populations in the rat gastrointestinal tract, resulting in a shift in the predominant bacteria towards tannin-resistant gram-negative Enterobacteriaceae and Bacteroides species. PMID:14766594

  16. The design of dual emitting cores for green thermally activated delayed fluorescent materials.

    PubMed

    Cho, Yong Joo; Jeon, Sang Kyu; Chin, Byung Doo; Yu, Eunsun; Lee, Jun Yeob

    2015-04-20

    Dual emitting cores for thermally activated delayed fluorescent (TADF) emitters were developed. Relative to the corresponding TADF emitter with a single emitting core the TADF emitter with a dual emitting core, 3,3',5,5'-tetra(carbazol-9-yl)-[1,1'-biphenyl]-2,2',6,6'-tetracarbonitrile, showed enhanced light absorption accompanied by a high photoluminescence quantum yield. The quantum and power efficiencies of the TADF devices were enhanced by the dual emitting cores. PMID:25727757

  17. Soil-Borne Bacterial Structure and Diversity Does Not Reflect Community Activity in Pampa Biome

    PubMed Central

    Lupatini, Manoeli; Suleiman, Afnan Khalil Ahmad; Jacques, Rodrigo Josemar Seminoti; Antoniolli, Zaida Inês; Kuramae, Eiko Eurya; de Oliveira Camargo, Flávio Anastácio; Roesch, Luiz Fernando Würdig

    2013-01-01

    The Pampa biome is considered one of the main hotspots of the world’s biodiversity and it is estimated that half of its original vegetation was removed and converted to agricultural land and tree plantations. Although an increasing amount of knowledge is being assembled regarding the response of soil bacterial communities to land use change, to the associated plant community and to soil properties, our understanding about how these interactions affect the microbial community from the Brazilian Pampa is still poor and incomplete. In this study, we hypothesized that the same soil type from the same geographic region but under distinct land use present dissimilar soil bacterial communities. To test this hypothesis, we assessed the soil bacterial communities from four land-uses within the same soil type by 454-pyrosequencing of 16S rRNA gene and by soil microbial activity analyzes. We found that the same soil type under different land uses harbor similar (but not equal) bacterial communities and the differences were controlled by many microbial taxa. No differences regarding diversity and richness between natural areas and areas under anthropogenic disturbance were detected. However, the measures of microbial activity did not converge with the 16S rRNA data supporting the idea that the coupling between functioning and composition of bacterial communities is not necessarily correlated. PMID:24146873

  18. The bacterial cytoplasm has glass-like properties and is fluidized by metabolic activity

    NASA Astrophysics Data System (ADS)

    Parry, Brad; Surovtsev, Ivan; Cabeen, Matthew; O'Hern, Corey; Dufresne, Eric; Jacobs-Wagner, Christine

    2014-03-01

    In eukaryotes, active transport involves motor proteins and cytoskeletal filaments. In contrast, bacteria (which lack cytoskeletal motor proteins) are thought to rely on diffusion for molecular transport, though the physical properties of the bacterial cytoplasm are poorly understood. Through single particle tracking of foreign particles of different sizes, we have found that the bacterial cytoplasm exhibits striking similarities to glass-forming liquids. Glass-forming liquids are noted for their metastability near the glass transition where their behavior changes from liquid-like to amorphous solid with even small perturbations. Particles of different sizes exhibit distinct dynamics and their mobility changes from fluid-like to glassy with increasing size. This size dependency provides an explanation for previous reports of both normal and anomalous diffusion in the bacterial cytoplasm. Moreover, we find that cellular metabolism attenuates the glassy properties of the bacterial cytoplasm. As a result, components that would otherwise be caged in narrow regions of confinement are able to explore the cytoplasmic space under metabolically active conditions. These findings have broad implications for our understanding of bacterial physiology as the glassy behavior of the cytoplasm impacts all intracellular processes involving large cellular components. Supported by the Howard Hughes Medical Institute.

  19. The Active Bacterial Community in a Pristine Confined Aquifer

    EPA Science Inventory

    This study of the active bacteria residing in a pristine confined aquifer provides unexpected insights into the ecology of iron-reducing and sulfate-reducing bacteria in the subsurface. At 18 wells in east-central Illinois, we trapped the microbes that attached to aquifer sedimen...

  20. Bacterial biomass and activity in the marginal ice zone of the northern Barents Sea

    NASA Astrophysics Data System (ADS)

    Tammert, Helen; Olli, Kalle; Sturluson, Maria; Hodal, Helene

    2008-10-01

    Bacteria in the Arctic Waters are well adapted to low temperatures and play a key role in the transformation of organic matter. However, the activity of planktonic bacteria at cellular level remains poorly understood. In this study, we use fluorescent markers (4',6'-diamidino-2-phenylindole (DAPI), 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), Live/Dead BacLight viability kit) to discriminate between bacterial cells with a variety of physiological activities in the 0-200 m water column and sinking particles. During two field studies (July 2003 and 2004), we covered nine stations in the northern Barents Sea. The median bacterial abundance (DAPI staining) in the upper 50 m layer was 0.9×10 6 cells ml -1 (range 0.2-3.2×10 6 cells ml -1) in 2003 and 0.5×10 6 cells ml -1 (range 0.2-1.0×10 6 cells ml -1) in 2004. Bacteria with sufficient electron transport activity to be stained with CTC were on average 10% of the total count and ca. 20% of the total cells had intact cell membranes. In the water column, proxies of substrate availability (POC, PON, chlorophyll a, primary production) and bacterial production (thymidine and leucine uptake) correlated strongly with total bacterial count, CTC-stained cells and cells with 'leaky' membrane (stained with propidium iodine), but not with the concentration of cells with intact cell membrane. Contrary to expectations, the proportion of CTC-stained bacteria was not higher in the sinking particles (captured with sediment traps) compared to the ambient water. However, out of the bacteria with intact cell membranes, a higher proportion scored as CTC positive in the aggregates compared to the ambient water. Bacterial cells with 'leaky' cell membranes formed the largest part of total cell count in all samples, and accumulated in sites with high microbial activity (sinking aggregates, chlorophyll maxima, layers of high primary and bacterial production). We hypothesize that the source of the bacterial cells with 'leaky' cell membranes

  1. Origin of optical activity in the purple bacterial photoreaction center

    SciTech Connect

    Mar, T.; Gingras, G.

    1995-07-18

    The photoreaction center (RC) of purple bacteria contains four bacteriochlorophyll (Bph) and two bacteriopheophytin (Bph) molecules as prosthetic groups. Their optical activity, as measured by circular dichroism (CD) spectroscopy, is largely increased in situ as compared to organic solutions. The all-exciton hypothesis posits that this enhanced optical activity is entirely due to excitonic interactions between the electronic transitions of all six bacteriochlorin molecules. Using the simple exciton theory, this model predicts that the near-infrared CD spectra should be conservative. The fact that they are not, whether the special pair of Bch (SP) that constitutes the primary electron donor is reduced or oxidized, has been explained by hyperchromic effects. The present work tests this hypothesis by successively eliminating the absorption and, therefore, the optical activity of the Bphs and of the non-special-pair (non-SP) Bchs. This was accomplished by trapping these pigments in their reduced state. RC preparations with the four non-SP bacteriochlorins trapped in their reduced state and, therefore, with an intact SP displayed conservative CD spectra. RC preparations with only the electronic transitions of SP and of one non-SP Bch also showed conservative CD spectra. These conservative CD spectra and their corresponding absorption spectra were simulated using simple exciton theory without assuming hyperchromic effects. Bleaching half of the 755-nm absorption band by phototrapping one of the two Bph molecules led to the complete disappearance of the corresponding CD band. This cannot be explained by the all-exciton hypothesis. These results suggest that the optical activity of the SP alone, or with one non-SP Bch, is due to excitonic interactions. They also suggest that the optical activity of the other three bacteriochlorins is due to other factors, such as pigment-protein interaction. 32 refs., 9 figs., 2 tabs.

  2. Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

  3. Bacterial differentiation via gradual activation of global regulators.

    PubMed

    Kovács, Ákos T

    2016-02-01

    Bacteria have evolved to adapt to various conditions and respond to certain stress conditions. The ability to sense and efficiently reply to these environmental effects involve versatile array of sensors and global or specific regulators. Interestingly, modulation of the levels of active global regulators enables bacteria to respond to diverse signals via a single central transcriptional regulator and to activate or repress certain differentiation pathways at a spatio-temporal manner. The Gram-positive Bacillus subtilis is an ideal bacterium to study how membrane bound and cytoplasmic sensor kinases affect the level of phosphorylated global regulator, Spo0A which in response activates genes related to sliding, biofilm formation, and sporulation. In addition, other global regulators, including the two-component system DegS-DegU, modulate overlapping and complementary genes in B. subtilis related to surface colonization and biofilm formation. The intertwinement of global regulatory systems also allows the accurate modulation of differentiation pathways. Studies in the last decade enable us to get a deeper insight into the role of global regulators on the smooth transition of developmental processes in B. subtilis. PMID:26458398

  4. Uranium Biomineralization As a Result of Bacterial Phosphatase Activity: Insights From Bacterial Isolates From a Contaminated Subsurface

    SciTech Connect

    Beazley, M.J.; Martinez, R.J.; Sobecky, P.A.; Webb, S.M.; Taillefert, M.; /Georgia Tech /SLAC, SSRL

    2007-10-31

    Uranium contamination is an environmental concern at the Department of Energy's Field Research Center in Oak Ridge, Tennessee. In this study, we investigated whether phosphate biomineralization, or the aerobic precipitation of U(VI)-phosphate phases facilitated by the enzymatic activities of microorganisms, offers an alternative to the more extensively studied anaerobic U(VI) bioreduction. Three heterotrophic bacteria isolated from FRC soils were studied for their ability to grow and liberate phosphate in the presence of U(VI) and an organophosphate between pH 4.5 and 7.0. The objectives were to determine whether the strains hydrolyzed sufficient phosphate to precipitate uranium, to determine whether low pH might have an effect on U(VI) precipitation, and to identify the uranium solid phase formed during biomineralization. Two bacterial strains hydrolyzed sufficient organophosphate to precipitate 73-95% total uranium after 120 h of incubation in simulated groundwater. The highest rates of uranium precipitation and phosphatase activity were observed between pH 5.0 and 7.0. EXAFS spectra identified the uranyl phosphate precipitate as an autunite/meta-autunite group mineral. The results of this study indicate that aerobic heterotrophic bacteria within a uranium-contaminated environment that can hydrolyze organophosphate, especially in low pH conditions, may play an important role in the bioremediation of uranium.

  5. Drivers shaping the diversity and biogeography of total and active bacterial communities in the South China Sea

    PubMed Central

    Zhang, Yao; Zhao, Zihao; Dai, Minhan; Jiao, Nianzhi; Herndl, Gerhard J

    2014-01-01

    To test the hypothesis that different drivers shape the diversity and biogeography of the total and active bacterial community, we examined the bacterial community composition along two transects, one from the inner Pearl River estuary to the open waters of the South China Sea (SCS) and the other from the Luzon Strait to the SCS basin, using 454 pyrosequencing of the 16S rRNA and 16S rRNA gene (V1-3 regions) and thereby characterizing the active and total bacterial community, respectively. The diversity and biogeographic patterns differed substantially between the active and total bacterial communities. Although the composition of both the total and active bacterial community was strongly correlated with environmental factors and weakly correlated with geographic distance, the active bacterial community displayed higher environmental sensitivity than the total community and particularly a greater distance effect largely caused by the active assemblage from deep waters. The 16S rRNA vs. rDNA relationships indicated that the active bacteria were low in relative abundance in the SCS. This might be due to a high competition between active bacterial taxa as indicated by our community network models. Based on these analyses, we speculate that high competition could cause some dispersal limitation of the active bacterial community resulting in a distinct distance-decay relationship. Altogether, our results indicated that the biogeographic distribution of bacteria in the SCS is the result of both environmental control and distance decay. PMID:24684298

  6. Thiolactomycin-Based Inhibitors of Bacterial β-Ketoacyl-ACP Synthases with in Vivo Activity.

    PubMed

    Bommineni, Gopal R; Kapilashrami, Kanishk; Cummings, Jason E; Lu, Yang; Knudson, Susan E; Gu, Chendi; Walker, Stephen G; Slayden, Richard A; Tonge, Peter J

    2016-06-01

    β-Ketoacyl-ACP synthases (KAS) are key enzymes involved in the type II bacterial fatty acid biosynthesis (FASII) pathway and are putative targets for antibacterial discovery. Several natural product KAS inhibitors have previously been reported, including thiolactomycin (TLM), which is produced by Nocardia spp. Here we describe the synthesis and characterization of optically pure 5R-thiolactomycin (TLM) analogues that show improved whole cell activity against bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA) and priority pathogens such as Francisella tularensis and Burkholderia pseudomallei. In addition, we identify TLM analogues with in vivo efficacy against MRSA and Klebsiella pneumoniae in animal models of infection. PMID:27187871

  7. Bacterial Riboswitches and Ribozymes Potently Activate the Human Innate Immune Sensor PKR.

    PubMed

    Hull, Chelsea M; Anmangandla, Ananya; Bevilacqua, Philip C

    2016-04-15

    The innate immune system provides the first line of defense against pathogens through the recognition of nonspecific patterns in RNA to protect the cell in a generalized way. The human RNA-activated protein kinase, PKR, is a dsRNA binding protein and an essential sensor in the innate immune response, which recognizes viral and bacterial pathogens through their RNAs. Upon activation via RNA-dependent autophosphorylation, PKR phosphorylates the eukaryotic initiation factor eIF2α, leading to termination of translation. PKR has a well-characterized role in recognizing viral RNA, where it binds long stretches of double-stranded RNA nonsequence specifically to promote activation; however, the mechanism by which bacterial RNA activates PKR and the mode by which self RNA avoids activating PKR are unknown. We characterized activation of PKR by three functional bacterial RNAs with pseudoknots and extensive tertiary structure: the cyclic di-GMP riboswitch, the glmS riboswitch-ribozyme, and the twister ribozyme, two of which are ligand-activated. These RNAs were found to activate PKR with comparable potency to long dsRNA. Enzymatic structure mapping in the absence and presence of PKR reveals a clear PKR footprint and provides a structural basis for how these bacterial RNAs activate PKR. In the case of the cyclic di-GMP riboswitch and the glmS riboswitch-ribozyme, PKR appears to dimerize on the peripheral double-stranded regions of the native RNA tertiary structure. Overall, these results provide new insights into how PKR acts as an innate immune signaling protein for the presence of bacteria and suggest a reason for the apparent absence of protein-free riboswitches and ribozymes in the human genome. PMID:27011290

  8. Anti-bacterial activity of Euphorbia fusiformis--a rare medicinal herb.

    PubMed

    Natarajan, D; Britto, S John; Srinivasan, K; Nagamurugan, N; Mohanasundari, C; Perumal, G

    2005-10-31

    Euphorbia fusiformis Buch.-Ham. ex. D.Don (Euphorbiaceae) is a rare medicinal herb. Aqueous and organic solvent extracts of the leaves and rootstocks were investigated for anti-bacterial properties by using disc diffusion and well-in agar methods, against pathogenic strains of Gram positive (Bacillus subtilis and Staphylococcus aureus) and Gram negative bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhii A and Salmonella typhii B). The different extracts differed significantly in their anti-bacterial properties with the methanolic extract being very effective followed by acetone and chloroform extracts. Aqueous and ethanolic extract showed very least activity. The result highlights that rootstock extracts had good anti-bacterial properties than leaf extracts. The results of this study support the use of this plant in traditional medicine to treat fever, wound infections and intestinal disorders. PMID:16159702

  9. Impedance spectroscopy of micro-Droplets reveals activation of Bacterial Mechanosensitive Channels in Hypotonic Solutions

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Aida; Alam, Muhammad A.

    Rapid detection of bacterial pathogens is of great importance in healthcare, food safety, environmental monitoring, and homeland security. Most bacterial detection platforms rely on binary fission (i.e. cell growth) to reach a threshold cell population that can be resolved by the sensing method. Since cell division depends on the bacteria type, the detection time of such methods can vary from hours to days. In contrast, in this work, we show that bacteria cells can be detected within minutes by relying on activation of specific protein channels, i.e. mechanosensitive channels (MS channels). When cells are exposed to hypotonic solutions, MS channels allow efflux of solutes to the external solution which leads to release the excessive membrane tension. Release of the cytoplasmic solutes, in turn, results in increase of the electrical conductance measured by droplet-based impedance sensing. The approach can be an effective technique for fast, pre-screening of bacterial contamination at ultra-low concentration.

  10. Active and Secretory IgA-Coated Bacterial Fractions Elucidate Dysbiosis in Clostridium difficile Infection

    PubMed Central

    Moya, Andrés; Vázquez-Castellanos, Jorge F.; Artacho, Alejandro; Chen, Xinhua; Kelly, Ciaran

    2016-01-01

    ABSTRACT The onset of Clostridium difficile infection (CDI) has been associated with treatment with wide-spectrum antibiotics. Antibiotic treatment alters the activity of gut commensals and may result in modified patterns of immune responses to pathogens. To study these mechanisms during CDI, we separated bacteria with high cellular RNA content (the active bacteria) and their inactive counterparts by fluorescence-activated cell sorting (FACS) of the fecal bacterial suspension. The gut dysbiosis due to the antibiotic treatment may result in modification of immune recognition of intestinal bacteria. The immune recognition patterns were assessed by FACS of bacterial fractions either coated or not with intestinal secretory immunoglobulin A (SIgA). We described the taxonomic distributions of these four bacterial fractions (active versus inactive and SIgA coated versus non-SIgA coated) by massive 16S rRNA gene amplicon sequencing and quantified the proportion of C. difficile toxin genes in the samples. The overall gut microbiome composition was more robustly influenced by antibiotics than by the C. difficile toxins. Bayesian networks revealed that the C. difficile cluster was preferentially SIgA coated during CDI. In contrast, in the CDI-negative group Fusobacterium was the characteristic genus of the SIgA-opsonized fraction. Lactobacillales and Clostridium cluster IV were mostly inactive in CDI-positive patients. In conclusion, although the proportion of C. difficile in the gut is very low, it is able to initiate infection during the gut dysbiosis caused by environmental stress (antibiotic treatment) as a consequence of decreased activity of the protective bacteria. IMPORTANCE C. difficile is a major enteric pathogen with worldwide distribution. Its expansion is associated with broad-spectrum antibiotics which disturb the normal gut microbiome. In this study, the DNA sequencing of highly active bacteria and bacteria opsonized by intestinal secretory immunoglobulin

  11. Active and Secretory IgA-Coated Bacterial Fractions Elucidate Dysbiosis in Clostridium difficile Infection.

    PubMed

    Džunková, Mária; Moya, Andrés; Vázquez-Castellanos, Jorge F; Artacho, Alejandro; Chen, Xinhua; Kelly, Ciaran; D'Auria, Giuseppe

    2016-01-01

    The onset of Clostridium difficile infection (CDI) has been associated with treatment with wide-spectrum antibiotics. Antibiotic treatment alters the activity of gut commensals and may result in modified patterns of immune responses to pathogens. To study these mechanisms during CDI, we separated bacteria with high cellular RNA content (the active bacteria) and their inactive counterparts by fluorescence-activated cell sorting (FACS) of the fecal bacterial suspension. The gut dysbiosis due to the antibiotic treatment may result in modification of immune recognition of intestinal bacteria. The immune recognition patterns were assessed by FACS of bacterial fractions either coated or not with intestinal secretory immunoglobulin A (SIgA). We described the taxonomic distributions of these four bacterial fractions (active versus inactive and SIgA coated versus non-SIgA coated) by massive 16S rRNA gene amplicon sequencing and quantified the proportion of C. difficile toxin genes in the samples. The overall gut microbiome composition was more robustly influenced by antibiotics than by the C. difficile toxins. Bayesian networks revealed that the C. difficile cluster was preferentially SIgA coated during CDI. In contrast, in the CDI-negative group Fusobacterium was the characteristic genus of the SIgA-opsonized fraction. Lactobacillales and Clostridium cluster IV were mostly inactive in CDI-positive patients. In conclusion, although the proportion of C. difficile in the gut is very low, it is able to initiate infection during the gut dysbiosis caused by environmental stress (antibiotic treatment) as a consequence of decreased activity of the protective bacteria. IMPORTANCE C. difficile is a major enteric pathogen with worldwide distribution. Its expansion is associated with broad-spectrum antibiotics which disturb the normal gut microbiome. In this study, the DNA sequencing of highly active bacteria and bacteria opsonized by intestinal secretory immunoglobulin A (SIg

  12. Enhancement of aerobic biodegradability potential of municipal waste activated sludge by ultrasonic aided bacterial disintegration.

    PubMed

    Kavitha, S; Jessin Brindha, G M; Sally Gloriana, A; Rajashankar, K; Yeom, Ick Tae; Rajesh Banu, J

    2016-01-01

    An investigation was performed to study the influence of ultrasonic aided bacterial disintegration on the aerobic degradability of sludge. In first phase of the study, effective floc disruption was achieved at an ultrasonic specific energy input of 2.45kJ/kg TS with 44.5mg/L of Extracellular Polymeric Substance (EPS) release including 0.035U/mL and 0.025U/mL protease and amylase activity respectively. In second phase, experimental outcomes revealed bacterial disintegration of floc disrupted-sludge showing a maximum solubilization of about 23% and was observed to be superior to bacterially disintegrated (11%) and control (6%), respectively. The result of aerobic biodegradability of ultrasonic aided bacterially pretreated sludge showed volatile solids (VS) degradation of about 40.2%. The kinetic study of aerobic biodegradability through non linear regression modelling reveals that floc disrupted sludge showed better biodegradability with decay constant of about 0.19d(-1) relatively higher than the control (0.14d(-1)) and bacterially disintegrated (0.17d(-1)) sludges. PMID:26479431

  13. Bacterial β-glucosidase function and metabolic activity depend on soil management in semiarid rainfed agriculture

    PubMed Central

    Cañizares, Rosa; Moreno, Beatriz; Benitez, Emilio

    2012-01-01

    Genomic and transcriptomic approaches were used to gain insights into the relationship between soil management and bacterial-mediated functions in an olive orchard agroecosystem. Four management practices were assessed in a 30-year trial in a semiarid Mediterranean region. Transcriptional activity of bacterial 16S rRNA genes increased in noncovered soils, indicating higher microbial maintenance requirements to thrive in less favorable environmental conditions. The 16S rRNA transcript:gene copy ratio confirmed this assumption and pointed toward a much higher constitutive expression from rRNA operons in noncovered soils and to even higher expression levels when spontaneous vegetation was removed chemically. As described for 16S rRNA, potential transcription did not reveal the real transcription of bacterial β-glucosidase genes, and higher gene expression in noncovered soils plus herbicides was evidenced. Since no relationship between total or soluble organic carbon and bacterial β-glucosidase transcription was found, the above hypothesis could indicate either that soluble organic carbon is not the main pool of enzyme-inducing substrates or that constitutive production of bacterial β-glucosidase enzymes increases as soil conditions worsen. PMID:22837821

  14. Bacterial Manipulation of NK Cell Regulatory Activity Increases Susceptibility to Listeria monocytogenes Infection

    PubMed Central

    Guthrie, Brandon S.; Schmidt, Rebecca L.; Jamieson, Amanda; Merkel, Patricia; Knight, Vijaya; Cole, Caroline M.; Raulet, David H.; Lenz, Laurel L.

    2016-01-01

    Natural killer (NK) cells produce interferon (IFN)-γ and thus have been suggested to promote type I immunity during bacterial infections. Yet, Listeria monocytogenes (Lm) and some other pathogens encode proteins that cause increased NK cell activation. Here, we show that stimulation of NK cell activation increases susceptibility during Lm infection despite and independent from robust NK cell production of IFNγ. The increased susceptibility correlated with IL-10 production by responding NK cells. NK cells produced IL-10 as their IFNγ production waned and the Lm virulence protein p60 promoted induction of IL-10 production by mouse and human NK cells. NK cells consequently exerted regulatory effects to suppress accumulation and activation of inflammatory myeloid cells. Our results reveal new dimensions of the role played by NK cells during Lm infection and demonstrate the ability of this bacterial pathogen to exploit the induction of regulatory NK cell activity to increase host susceptibility. PMID:27295349

  15. Bacterial Manipulation of NK Cell Regulatory Activity Increases Susceptibility to Listeria monocytogenes Infection.

    PubMed

    Clark, Sarah E; Filak, Holly C; Guthrie, Brandon S; Schmidt, Rebecca L; Jamieson, Amanda; Merkel, Patricia; Knight, Vijaya; Cole, Caroline M; Raulet, David H; Lenz, Laurel L

    2016-06-01

    Natural killer (NK) cells produce interferon (IFN)-γ and thus have been suggested to promote type I immunity during bacterial infections. Yet, Listeria monocytogenes (Lm) and some other pathogens encode proteins that cause increased NK cell activation. Here, we show that stimulation of NK cell activation increases susceptibility during Lm infection despite and independent from robust NK cell production of IFNγ. The increased susceptibility correlated with IL-10 production by responding NK cells. NK cells produced IL-10 as their IFNγ production waned and the Lm virulence protein p60 promoted induction of IL-10 production by mouse and human NK cells. NK cells consequently exerted regulatory effects to suppress accumulation and activation of inflammatory myeloid cells. Our results reveal new dimensions of the role played by NK cells during Lm infection and demonstrate the ability of this bacterial pathogen to exploit the induction of regulatory NK cell activity to increase host susceptibility. PMID:27295349

  16. Bacterial diversity is strongly associated with historical penguin activity in an Antarctic lake sediment profile

    PubMed Central

    Zhu, Renbin; Shi, Yu; Ma, Dawei; Wang, Can; Xu, Hua; Chu, Haiyan

    2015-01-01

    Current penguin activity in Antarctica affects the geochemistry of sediments and their microbial communities; the effects of historical penguin activity are less well understood. Here, bacterial diversity in ornithogenic sediment was investigated using high-throughput pyrosequencing. The relative abundances of dominant phyla were controlled by the amount of historical penguin guano deposition. Significant positive correlations were found between both the bacterial richness and diversity, and the relative penguin number (p < 0.01); this indicated that historical penguin activity drove the vertical distribution of the bacterial communities. The lowest relative abundances of individual phyla corresponded to lowest number of penguin population at 1,800–2,300 yr BP during a drier and colder period; the opposite was observed during a moister and warmer climate (1,400–1,800 yr BP). This study shows that changes in the climate over millennia affected penguin populations and the outcomes of these changes affect the sediment bacterial community today. PMID:26601753

  17. Are the actively respiring cells (CTC+) those responsible for bacterial production in aquatic environments?

    PubMed

    Servais, P; Agogué, H; Courties, C; Joux, F; Lebaron, P

    2001-04-01

    The 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) staining method is commonly and increasingly used to detect and to enumerate actively respiring cells (CTC+ cells) in aquatic systems. However, this method remains controversial since some authors promote this technique while others pointed out several drawbacks of the method. Using flow cytometry (FCM), we showed that CTC staining kinetics vary greatly from one sample to another. Therefore, there is no universal staining protocol that can be applied to aquatic bacterial communities. Furthermore, using (3)H-leucine incorporation, it was shown that the CTC dye has a rapid toxic effect on bacterial cells by inhibiting protein synthesis, a key physiological function. The coupling of radioactive labelling with cell sorting by FCM suggested that CTC+ cells contribute to less than 60% of the whole bacterial activity determined at the community level. From these results, it is clearly demonstrated that the CTC method is not valid to detect active bacteria, i.e. cells responsible for bacterial production. PMID:11295456

  18. Antibacterial activity and mechanism of action of auranofin against multi-drug resistant bacterial pathogens.

    PubMed

    Thangamani, Shankar; Mohammad, Haroon; Abushahba, Mostafa F N; Sobreira, Tiago J P; Hedrick, Victoria E; Paul, Lake N; Seleem, Mohamed N

    2016-01-01

    Traditional methods employed to discover new antibiotics are both a time-consuming and financially-taxing venture. This has led researchers to mine existing libraries of clinical molecules in order to repurpose old drugs for new applications (as antimicrobials). Such an effort led to the discovery of auranofin, a drug initially approved as an anti-rheumatic agent, which also possesses potent antibacterial activity in a clinically achievable range. The present study demonstrates auranofin's antibacterial activity is a complex process that involves inhibition of multiple biosynthetic pathways including cell wall, DNA, and bacterial protein synthesis. We also confirmed that the lack of activity of auranofin observed against Gram-negative bacteria is due to the permeability barrier conferred by the outer membrane. Auranofin's ability to suppress bacterial protein synthesis leads to significant reduction in the production of key methicillin-resistant Staphylococcus aureus (MRSA) toxins. Additionally, auranofin is capable of eradicating intracellular MRSA present inside infected macrophage cells. Furthermore, auranofin is efficacious in a mouse model of MRSA systemic infection and significantly reduces the bacterial load in murine organs including the spleen and liver. Collectively, this study provides valuable evidence that auranofin has significant promise to be repurposed as a novel antibacterial for treatment of invasive bacterial infections. PMID:26936660

  19. Antibacterial activity and mechanism of action of auranofin against multi-drug resistant bacterial pathogens

    PubMed Central

    Thangamani, Shankar; Mohammad, Haroon; Abushahba, Mostafa F. N.; Sobreira, Tiago J. P.; Hedrick, Victoria E.; Paul, Lake N.; Seleem, Mohamed N.

    2016-01-01

    Traditional methods employed to discover new antibiotics are both a time-consuming and financially-taxing venture. This has led researchers to mine existing libraries of clinical molecules in order to repurpose old drugs for new applications (as antimicrobials). Such an effort led to the discovery of auranofin, a drug initially approved as an anti-rheumatic agent, which also possesses potent antibacterial activity in a clinically achievable range. The present study demonstrates auranofin’s antibacterial activity is a complex process that involves inhibition of multiple biosynthetic pathways including cell wall, DNA, and bacterial protein synthesis. We also confirmed that the lack of activity of auranofin observed against Gram-negative bacteria is due to the permeability barrier conferred by the outer membrane. Auranofin’s ability to suppress bacterial protein synthesis leads to significant reduction in the production of key methicillin-resistant Staphylococcus aureus (MRSA) toxins. Additionally, auranofin is capable of eradicating intracellular MRSA present inside infected macrophage cells. Furthermore, auranofin is efficacious in a mouse model of MRSA systemic infection and significantly reduces the bacterial load in murine organs including the spleen and liver. Collectively, this study provides valuable evidence that auranofin has significant promise to be repurposed as a novel antibacterial for treatment of invasive bacterial infections. PMID:26936660

  20. Impact of freshwater inflow on bacterial abundance and activity in the estuarine system Ria de Aveiro

    NASA Astrophysics Data System (ADS)

    Santos, Luísa; Vaz, Leandro; Marcial Gomes, Newton C.; Vaz, Nuno; Dias, João Miguel; Cunha, Ângela; Almeida, Adelaide

    2014-02-01

    The influence of freshwater flow on bacterial communities in the estuarine system Ria de Aveiro (Portugal) was investigated at two sites differently impacted by river inputs, representative of the marine and brackish water zones of the estuary. Sampling events were clustered based on hydrological features. The hydrodynamic was simulated with a Lagrangian model and related to microbiological parameters. Estuarine bacteria responded to different freshwater regimes developing distinct patterns of abundance and activity at the marine and brackish water zones. A circulation pattern induced by high river inflow produced vertical stratification in the marine zone, promoting a seaward flux of bacterioplankton, and stimulating the import of riverine phytoplankton and particle-attached bacteria to the brackish water zone. Advective transport and resuspension processes contributed to a 3-times increase in abundance of particle-attached bacteria during intense freshwater inputs. Additionally, bacterial activity in the estuary was controlled by inorganic nitrogen, responding to different freshwater inputs, which, in association with different prevailing sources of organic substrates induced significant changes in bacterial production. The dynamic and main controlling factors of bacterial communities are clearly impacted by freshwater inputs. Therefore, significant changes in the recycling of nutrients by microbial activities can be expected from alterations in freshwater inputs either related to global climate change or regional hydrological regimes.

  1. Inhibition of bacterial activity in acid mine drainage

    NASA Astrophysics Data System (ADS)

    Singh, Gurdeep; Bhatnagar, Miss Mridula

    1988-12-01

    Acid mine drainage water give rise to rapid growth and activity of an iron- and sulphur- oxidizing bacterium Thiobacillus ferrooxidians which greatly accelerate acid producing reactions by oxidation of pyrite material associated with coal and adjoining strata. The role of this bacterium in production of acid mine drainage is described. This study presents the data which demonstrate the inhibitory effect of certain organic acids, sodium benzoate, sodium lauryl sulphate, quarternary ammonium compounds on the growth of the acidophilic aerobic autotroph Thiobacillus ferrooxidians. In each experiment, 10 milli-litres of laboratory developed culture of Thiobacillus ferrooxidians was added to 250 milli-litres Erlenmeyer flask containing 90 milli-litres of 9-k media supplemented with FeSO4 7H2O and organic compounds at various concentrations. Control experiments were also carried out. The treated and untreated (control) samples analysed at various time intervals for Ferrous Iron and pH levels. Results from this investigation showed that some organic acids, sodium benzoate, sodium lauryl sulphate and quarternary ammonium compounds at low concentration (10-2 M, 10-50 ppm concentration levels) are effective bactericides and able to inhibit and reduce the Ferrous Iron oxidation and acidity formation by inhibiting the growth of Thiobacillus ferrooxidians is also discussed and presented

  2. Nano-engineered living bacterial motors for active microfluidic mixing.

    PubMed

    Al-Fandi, M; Jaradat, M A K; Fandi, K; Beech, J P; Tegenfeldt, J O; Yih, T C

    2010-09-01

    Active micromixers with rotating elements are attractive microfluidic actuators in many applications because of their mixing ability at a short distance. However, miniaturising the impeller design poses technical challenges including the fabrication and driving means. As a possible solution inspired by macro magnetic bar-stirrers, this study proposes the use of tethered, rotating bacteria as mixing elements. A tethered cell is a genetically engineered, harmless Escherichia coli (E. coli) attached to a surface by a single, shortened flagellum. The tethered flagellum acts as a pivot around which the entire cell body smoothly rotates. Videomicroscopy, image analysis and computational fluid dynamics (CFD) are utilised to demonstrate a proof-of-concept for the micro mixing process. Flow visualisation experiments show that a approximately 3 microm long tethered E. coli rotating at approximately 240 rpm can circulate a 1 microm polystyrene bead in the adjacent area at an average speed of nearly 4 microm/s. The Peclet (Peb) number for the stirred bead is evaluated to approximately 4. CFD simulations show that the rotary motion of a tethered E. coli rotating at 240 rpm can generate fluid velocities, up to 37 microm/s bordering the cell envelop. Based on these simulations, the Strouhal number (St) is calculated to about 2. This hybrid bio-inorganic micromxer could be used as a local, disposable mixer. PMID:20726672

  3. Depth variation of bacterial extracellular enzyme activity and population diversity in the northeastern North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Davey, Katherine E.; Kirby, Richard R.; Turley, Carol M.; Weightman, Andrew J.; Fry, John C.

    Distinct profiles of extracellular proteolytic enzyme activity were observed in the water column of the North Atlantic, with maximum potential proteolytic activity occurring in the top 35 m. The proteolytic enzyme Vmax values varied significantly and decreased from 1.46 nM min -1 in surface waters to 0.365 nM min -1 at 100 m. In contrast, Km values increased with depth from about 70 to 360 μM. Cell-associated enzymes accounted for the majority of the observed proteolytic activity. Dissolved enzymes comprised only 30-40% of the total extracellular enzyme activity and exhibited a low substrate affinity ( Km=˜1000 μM). These observations indicate clear stratification of bacterial associated extracellular enzyme activity, with the maximum activity in surface waters. This is consistent with some environmental changes in the water column, especially algal biomass and nitrate concentration. Bacterial mediated nitrogen remineralization in surface waters was approximately three times the total nitrogen demand of phytoplankton and bacteria. We determined bacterial population diversity using 16S rRNA sequence analysis and found evidence for stratification, with a higher representation of the Cytophaga/Flexibacter/Bacteriodes group at 5 m compared to 100 m. No similar stratification was observed among the α-proteobacterial SAR11 cluster, which were especially prevalent in the PRIME eddy. However, sequences phylogenetically related to another marine cluster, SAR122, were only observed at 100 m. We suggest that stratification of proteolytic activity within the water column may be explained at least in part, by differences in the composition of the bacterial community.

  4. HCV core protein induces hepatic lipid accumulation by activating SREBP1 and PPAR{gamma}

    SciTech Connect

    Kim, Kook Hwan; Hong, Sung Pyo; Kim, KyeongJin; Park, Min Jung; Kim, Kwang Jin; Cheong, JaeHun . E-mail: molecule85@pusan.ac.kr

    2007-04-20

    Hepatic steatosis is a common feature in patients with chronic hepatitis C virus (HCV) infection. HCV core protein plays an important role in the development of hepatic steatosis in HCV infection. Because SREBP1 (sterol regulatory element binding protein 1) and PPAR{gamma} (peroxisome proliferators-activated receptor {gamma}) are involved in the regulation of lipid metabolism of hepatocyte, we sought to determine whether HCV core protein may impair the expression and activity of SREBP1 and PPAR{gamma}. In this study, it was demonstrated that HCV core protein increases the gene expression of SREBP1 not only in Chang liver, Huh7, and HepG2 cells transiently transfected with HCV core protein expression plasmid, but also in Chang liver-core stable cells. Furthermore, HCV core protein enhanced the transcriptional activity of SREBP1. In addition, HCV core protein elevated PPAR{gamma} transcriptional activity. However, HCV core protein had no effect on PPAR{gamma} gene expression. Finally, we showed that HCV core protein stimulates the genes expression of lipogenic enzyme and fatty acid uptake associated protein. Therefore, our finding provides a new insight into the mechanism of hepatic steatosis by HCV infection.

  5. Fast isolation of highly active photosystem II core complexes from spinach.

    PubMed

    Wang, Zhao-Gai; Xu, Tian-Hua; Liu, Cheng; Yang, Chun-Hong

    2010-09-01

    Purification of photosystem II (PSII) core complexes is a time-consuming and low-efficiency process. In order to isolate pure and active PSII core complexes in large amounts, we have developed a fast method to isolate highly active monomeric and dimeric PSII core complexes from spinach leaves by using sucrose gradient ultracentrifugation. By using a vertical rotor the process was completed significantly faster compared with a swing-out rotor. In order to keep the core complexes in high activity, the whole isolation procedure was performed in the presence of glycine betain and pH at 6.3. The isolated pigment-protein complexes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, 77 K fluorescence spectroscopy and high performance liquid chromatography. Our results show that this method is a better choice for quick and efficient isolation of functionally active PSII core complexes. PMID:20738723

  6. Antiviral activity and specific modes of action of bacterial prodigiosin against Bombyx mori nucleopolyhedrovirus in vitro.

    PubMed

    Zhou, Wei; Zeng, Cheng; Liu, RenHua; Chen, Jie; Li, Ru; Wang, XinYan; Bai, WenWen; Liu, XiaoYuan; Xiang, TingTing; Zhang, Lin; Wan, YongJi

    2016-05-01

    Prodigiosin, the tripyrrole red pigment, is a bacterial secondary metabolite with multiple bioactivities; however, the antiviral activity has not been reported yet. In the present study, we found the antiviral activity of bacterial prodigiosin on Bombyx mori nucleopolyhedrovirus (BmNPV)-infected cells in vitro, with specific modes of action. Prodigiosin at nontoxic concentrations selectively killed virus-infected cells, inhibited viral gene transcription, especially viral early gene ie-1, and prevented virus-mediated membrane fusion. Under prodigiosin treatment, both progeny virus production and viral DNA replication were significantly inhibited. Fluorescent assays showed that prodigiosin predominantly located in cytoplasm which suggested it might interact with cytoplasm factors to inhibit virus replication. In conclusion, the present study clearly indicates that prodigiosin possesses significant antiviral activity against BmNPV. PMID:26685856

  7. Screening of anti-bacterial activity of medicinal plants from Belize (Central America).

    PubMed

    Camporese, A; Balick, M J; Arvigo, R; Esposito, R G; Morsellino, N; De Simone, F; Tubaro, A

    2003-07-01

    Twenty-one extracts from seven herbal drugs, Aristolochia trilobata (Aristolochiaceae) leaves and bark, Bursera simaruba (Burseraceae) bark, Guazuma ulmifolia (Sterculiaceae) bark, Hamelia patens (Rubiaceae) leaves and Syngonium podophyllum (Araceae) leaves and bark, used in traditional medicine of Belize (Central America) as deep and superficial wound healers, were evaluated for their anti-bacterial properties. Activity was tested against standard strains of Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212. Almost all the extracts were able to inhibit the growth of one or more of the bacterial strains, except that of Enterococcus faecalis. For the first time an anti-microbial activity is reported for Aristolochia trilobata as well as for Syngonium podophyllum. The hexane extracts of Aristolochia trilobata leaves and bark were the most active extracts against Staphylococcus aureus (MIC=0.31 and 0.625mg/ml, respectively). PMID:12787962

  8. Bacterial lipids activate, synergize, and inhibit a developmental switch in choanoflagellates

    PubMed Central

    Woznica, Arielle; Cantley, Alexandra M.; Beemelmanns, Christine; Freinkman, Elizaveta; Clardy, Jon; King, Nicole

    2016-01-01

    In choanoflagellates, the closest living relatives of animals, multicellular rosette development is regulated by environmental bacteria. The simplicity of this evolutionarily relevant interaction provides an opportunity to identify the molecules and regulatory logic underpinning bacterial regulation of development. We find that the rosette-inducing bacterium Algoriphagus machipongonensis produces three structurally divergent classes of bioactive lipids that, together, activate, enhance, and inhibit rosette development in the choanoflagellate Salpingoeca rosetta. One class of molecules, the lysophosphatidylethanolamines (LPEs), elicits no response on its own but synergizes with activating sulfonolipid rosette-inducing factors (RIFs) to recapitulate the full bioactivity of live Algoriphagus. LPEs, although ubiquitous in bacteria and eukaryotes, have not previously been implicated in the regulation of a host–microbe interaction. This study reveals that multiple bacterially produced lipids converge to activate, enhance, and inhibit multicellular development in a choanoflagellate. PMID:27354530

  9. Robustness of Nuclear Core Activity Reconstruction by Data Assimilation

    NASA Astrophysics Data System (ADS)

    Bouriquet, Bertrand; Argaud, Jean-Philippe; Erhard, Patrick; Massart, Sébastien; Ponçot, Angélique; Ricci, Sophie; Thual, Olivier

    Inspired from meteorological applications, data assimilation techniques can be used to perform an optimal reconstruction of the neutronic field in a nuclear reactor core. Measurements and simulation information, coming from a numerical model, are merged together to build a better estimation of the whole field. In this paper, we first study the robustness of the method when the amount of measured information varies. We then study the influence of the nature of the instruments and their spatial repartition on the efficiency of the field reconstruction. This study also highlights the instruments providing most information within a data assimilation procedure. The study of various network configurations of instruments in the nuclear core establishes that the influence of each instrument depends both on the individual instrumentation location as well as on the chosen network.

  10. Sequential laser and ultrasonic wave generation of TiO2@Ag core-shell nanoparticles and their anti-bacterial properties.

    PubMed

    Hamad, Abubaker Hassan; Li, Lin; Liu, Zhu; Zhong, Xiang Li; Wang, Tao

    2016-02-01

    Core-shell nanoparticles have unusual physical, chemical and biological properties. Until now, for the Ag and TiO2 combination, only Ag core and TiO2 shell nanoparticles have been practically demonstrated. In this investigation, novel TiO2@Ag core-shell (TiO2 core and Ag shell) nanoparticles were produced via ultrasonic vibration of Ag-TiO2 compound nanoparticles. A bulk Ti/Ag alloy plate was used to generate colloidal Ag-TiO2 compound nanoparticles via picosecond laser ablation in deionised water. The colloidal nanoparticles were then sonicated in an ultrasonic bath to generate TiO2@Ag core-shell nanoparticles. They were characterised using a UV-VIS spectrometer, transmission electron microscopy (TEM), high-angle annular dark-field-Scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The Ag-TiO2 compound and the TiO2@Ag core-shell nanoparticles were examined for their antibacterial activity against Escherichia coli (E. coli) JM109 strain bacteria and compared with those of Ag and TiO2 nanoparticles. The antibacterial activity of the core-shell nanoparticles was slightly better than that of the compound nanoparticles at the same concentration under standard laboratory light conditions and both were better than the TiO2 nanoparticles but not as good as the Ag nanoparticles. PMID:26714980

  11. Survival of selected bacterial species in sterilized activated carbon filters and biological activated carbon filters.

    PubMed Central

    Rollinger, Y; Dott, W

    1987-01-01

    The survival of selected hygienically relevant bacterial species in activated carbon (AC) filters on a bench scale was investigated. The results revealed that after inoculation of the test strains the previously sterilized AC absorbed all bacteria (10(6) to 10(7)). After a period of 6 to 13 days without countable bacteria in the effluent, the numbers of Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida increased up to 10(4) to 10(5) CFU/ml of effluent and 10(6) to 10(7) CFU/g of AC. When Klebsiella pneumoniae and Streptococcus faecalis were used, no growth in filters could be observed. The numbers of E. coli, P. aeruginosa, and P. putida, however, decreased immediately and showed no regrowth in nonsterile AC from a filter which had been continuously connected to running tap water for 2 months. Under these conditions an autochthonous microflora developed on the carbon surface which could be demonstrated by scanning electron microscopy and culturing methods (heterotrophic plate count). These bacteria reduced E. coli, P. aeruginosa, and P. putida densities in the effluent by a factor of more than 10(5) within 1 to 5 days. The hypothesis that antagonistic substances of the autochthonous microflora were responsible for the elimination of the artificial contamination could not be confirmed because less than 1% of the isolates of the autochthonous microflora were able to produce such substances as indicated by in vitro tests. Competition for limiting nutrients was thought to be the reason for the observed effects. PMID:3579281

  12. Human NAIP and mouse NAIP1 recognize bacterial type III secretion needle protein for inflammasome activation.

    PubMed

    Yang, Jieling; Zhao, Yue; Shi, Jianjin; Shao, Feng

    2013-08-27

    Inflammasome mediated by central nucleotide-binding and oligomerization domain (NOD)-like receptor (NLR) protein is critical for defense against bacterial infection. Here we show that type III secretion system (T3SS) needle proteins from several bacterial pathogens, including Salmonella typhimurium, enterohemorrhagic Escherichia coli, Shigella flexneri, and Burkholderia spp., can induce robust inflammasome activation in both human monocyte-derived and mouse bone marrow macrophages. Needle protein activation of human NRL family CARD domain containing 4 (NLRC4) inflammasome requires the sole human neuronal apoptosis inhibitory protein (hNAIP). Among the seven mouse NAIPs, NAIP1 functions as the mouse counterpart of hNAIP. We found that NAIP1 recognition of T3SS needle proteins was more robust in mouse dendritic cells than in bone marrow macrophages. Needle proteins, as well as flagellin and rod proteins from five different bacteria, exhibited differential and cell type-dependent inflammasome-stimulating activity. Comprehensive profiling of the three types of NAIP ligands revealed that NAIP1 sensing of the needle protein dominated S. flexneri-induced inflammasome activation, particularly in dendritic cells. hNAIP/NAIP1 and NAIP2/5 formed a large oligomeric complex with NLRC4 in the presence of corresponding bacterial ligands, and could support reconstitution of the NLRC4 inflammasome in a ligand-specific manner. PMID:23940371

  13. A Systems Biological Approach Reveals Multiple Crosstalk Mechanism between Gram-Positive and Negative Bacterial Infections: An Insight into Core Mechanism and Unique Molecular Signatures

    PubMed Central

    Thangam, Berla; Ahmed, Shiek S. S. J.

    2014-01-01

    Background Bacterial infections remain a major threat and a leading cause of death worldwide. Most of the bacterial infections are caused by gram-positive and negative bacteria, which are recognized by Toll-like receptor (TLR) 2 and 4, respectively. Activation of these TLRs initiates multiple pathways that subsequently lead to effective immune response. Although, both the TLRs share common signaling mechanism yet they may exhibit specificity as well, resulting in the release of diverse range of inflammatory mediators which could be used as candidate biomolecules for bacterial infections. Results We adopted systems biological approach to identify signaling pathways mediated by TLRs to determine candidate molecules associated with bacterial infections. We used bioinformatics concepts, including literature mining to construct protein-protein interaction network, prioritization of TLRs specific nodes using microarray data and pathway analysis. Our constructed PPI network for TLR 2 (nodes: 4091 and edges: 66068) and TLR 4 (node: 4076 and edges: 67898) showed 3207 common nodes, indicating that both the TLRs might share similar signaling events that are attributed to cell migration, MAPK pathway and several inflammatory cascades. Our results propose the potential collaboration between the shared signaling pathways of both the receptors may enhance the immune response against invading pathogens. Further, to identify candidate molecules, the TLRs specific nodes were prioritized using microarray differential expressed genes. Of the top prioritized TLR 2 molecules, 70% were co-expressed. A similar trend was also observed within TLR 4 nodes. Further, most of these molecules were preferentially found in blood plasma for feasible diagnosis. Conclusions The analysis reveals the common and unique mechanism regulated by both the TLRs that provide a broad perspective of signaling events in bacterial infections. Further, the identified candidate biomolecules could potentially aid

  14. Controlled release and antibacterial activity of tetracycline hydrochloride-loaded bacterial cellulose composite membranes.

    PubMed

    Shao, Wei; Liu, Hui; Wang, Shuxia; Wu, Jimin; Huang, Min; Min, Huihua; Liu, Xiufeng

    2016-07-10

    Bacterial cellulose (BC) is widely used in biomedical applications. In this study, we prepared an antibiotic drug tetracycline hydrochloride (TCH)-loaded bacterial cellulose (BC) composite membranes, and evaluated the drug release, antibacterial activity and biocompatibility. The structure and morphology of the fabricated BC-TCH composite membranes were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TCH release results show that the incorporation of BC matrix to load TCH is able to control the release. In vitro antibacterial assay demonstrate that the developed BC-TCH composites displayed excellent antibacterial activity solely associated with the loaded TCH drug. More importantly, the BC-TCH composite membranes display good biocompatibility. These characteristics of BC-TCH composite membranes indicate that they may successfully serve as wound dressings and other medical biomaterials. PMID:27106158

  15. A Stable Bacterial Peroxidase with Novel Halogenating Activity and an Autocatalytically Linked Heme Prosthetic Group*

    PubMed Central

    Auer, Markus; Gruber, Clemens; Bellei, Marzia; Pirker, Katharina F.; Zamocky, Marcel; Kroiss, Daniela; Teufer, Stefan A.; Hofbauer, Stefan; Soudi, Monika; Battistuzzi, Gianantonio; Furtmüller, Paul G.; Obinger, Christian

    2013-01-01

    Reconstructing the phylogenetic relationships of the main evolutionary lines of the mammalian peroxidases lactoperoxidase and myeloperoxidase revealed the presence of novel bacterial heme peroxidase subfamilies. Here, for the first time, an ancestral bacterial heme peroxidase is shown to possess a very high bromide oxidation activity (besides conventional peroxidase activity). The recombinant protein allowed monitoring of the autocatalytic peroxide-driven formation of covalent heme to protein bonds. Thereby, the high spin ferric rhombic heme spectrum became similar to lactoperoxidase, the standard reduction potential of the Fe(III)/Fe(II) couple shifted to more positive values (−145 ± 10 mV at pH 7), and the conformational and thermal stability of the protein increased significantly. We discuss structure-function relationships of this new peroxidase in relation to its mammalian counterparts and ask for its putative physiological role. PMID:23918925

  16. Teaching the Common Core Math Standards with Hands-On Activities, Grades 6-8

    ERIC Educational Resources Information Center

    Muschla, Judith A.; Muschla, Gary Robert; Muschla, Erin

    2012-01-01

    The new Common Core State Standards for Mathematics have been formulated to provide students with instruction that will help them acquire a thorough knowledge of math at their grade level, which will in turn enable them to move on to higher mathematics with competence and confidence. "Hands-on Activities for Teaching the Common Core Math…

  17. Designing Class Activities to Meet Specific Core Training Competencies: A Developmental Approach

    ERIC Educational Resources Information Center

    Guth, Lorraine J.; McDonnell, Kelly A.

    2004-01-01

    This article presents a developmental model for designing and utilizing class activities to meet specific Association for Specialists in Group Work (ASGW) core training competencies for group workers. A review of the relevant literature about teaching group work and meeting core training standards is provided. The authors suggest a process by…

  18. Bacterial skin infections, active component, U.S. Armed Forces, 2000-2012.

    PubMed

    2013-12-01

    From 2000 through 2012, health care records of the Military Health System documented 998,671 incident cases of bacterial skin infections among active component members of the U.S. Armed Forces. Most cases (97.3%) were identified from records of outpatient medical encounters rather than hospitalizations. Cellulitis accounted for half (50.9%) of all cases of bacterial skin infection but 96 percent of associated hospital bed days. Of all cases, 42.3 percent were "other" skin infections (i.e., folliculitis, impetigo, pyoderma, pyogenic granuloma, other and unspecified infections). The remainder were attributable to carbuncles/furuncles (6.6%) and erysipelas (0.1%). Rates of infection were higher among female service members except for "other" skin infections. In general, the highest rates were associated with youth, recruit trainee status, and junior enlisted rank; however, rates of erysipelas were highest among those 50 years and older. Annual incidence rates of all bacterial skin infections have increased greatly since 2000. During the entire period, such infections required more than 1.4 million health care encounters and 94,000 hospital bed-days (equivalent to 257 years of lost duty time). The prevention, early diagnosis, and treatment of bacterial skin infections, particularly in high risk settings, deserve continued emphasis. PMID:24428536

  19. Multisubstrate Isotope Labeling and Metagenomic Analysis of Active Soil Bacterial Communities

    PubMed Central

    Verastegui, Y.; Cheng, J.; Engel, K.; Kolczynski, D.; Mortimer, S.; Lavigne, J.; Montalibet, J.; Romantsov, T.; Hall, M.; McConkey, B. J.; Rose, D. R.; Tomashek, J. J.; Scott, B. R.

    2014-01-01

    ABSTRACT Soil microbial diversity represents the largest global reservoir of novel microorganisms and enzymes. In this study, we coupled functional metagenomics and DNA stable-isotope probing (DNA-SIP) using multiple plant-derived carbon substrates and diverse soils to characterize active soil bacterial communities and their glycoside hydrolase genes, which have value for industrial applications. We incubated samples from three disparate Canadian soils (tundra, temperate rainforest, and agricultural) with five native carbon (12C) or stable-isotope-labeled (13C) carbohydrates (glucose, cellobiose, xylose, arabinose, and cellulose). Indicator species analysis revealed high specificity and fidelity for many uncultured and unclassified bacterial taxa in the heavy DNA for all soils and substrates. Among characterized taxa, Actinomycetales (Salinibacterium), Rhizobiales (Devosia), Rhodospirillales (Telmatospirillum), and Caulobacterales (Phenylobacterium and Asticcacaulis) were bacterial indicator species for the heavy substrates and soils tested. Both Actinomycetales and Caulobacterales (Phenylobacterium) were associated with metabolism of cellulose, and Alphaproteobacteria were associated with the metabolism of arabinose; members of the order Rhizobiales were strongly associated with the metabolism of xylose. Annotated metagenomic data suggested diverse glycoside hydrolase gene representation within the pooled heavy DNA. By screening 2,876 cloned fragments derived from the 13C-labeled DNA isolated from soils incubated with cellulose, we demonstrate the power of combining DNA-SIP, multiple-displacement amplification (MDA), and functional metagenomics by efficiently isolating multiple clones with activity on carboxymethyl cellulose and fluorogenic proxy substrates for carbohydrate-active enzymes. PMID:25028422

  20. Bacterial Outer Membrane Vesicles Mediate Cytosolic Localization of LPS and Caspase-11 Activation.

    PubMed

    Vanaja, Sivapriya Kailasan; Russo, Ashley J; Behl, Bharat; Banerjee, Ishita; Yankova, Maya; Deshmukh, Sachin D; Rathinam, Vijay A K

    2016-05-19

    Sensing of lipopolysaccharide (LPS) in the cytosol triggers caspase-11 activation and is central to host defense against Gram-negative bacterial infections and to the pathogenesis of sepsis. Most Gram-negative bacteria that activate caspase-11, however, are not cytosolic, and the mechanism by which LPS from these bacteria gains access to caspase-11 in the cytosol remains elusive. Here, we identify outer membrane vesicles (OMVs) produced by Gram-negative bacteria as a vehicle that delivers LPS into the cytosol triggering caspase-11-dependent effector responses in vitro and in vivo. OMVs are internalized via endocytosis, and LPS is released into the cytosol from early endosomes. The use of hypovesiculating bacterial mutants, compromised in their ability to generate OMVs, reveals the importance of OMVs in mediating the cytosolic localization of LPS. Collectively, these findings demonstrate a critical role for OMVs in enabling the cytosolic entry of LPS and, consequently, caspase-11 activation during Gram-negative bacterial infections. PMID:27156449

  1. The Effect of Lipopolysaccharide Core Oligosaccharide Size on the Electrostatic Binding of Antimicrobial Proteins to Models of the Gram Negative Bacterial Outer Membrane.

    PubMed

    Clifton, Luke A; Ciesielski, Filip; Skoda, Maximilian W A; Paracini, Nicolò; Holt, Stephen A; Lakey, Jeremy H

    2016-04-12

    Understanding the electrostatic interactions between bacterial membranes and exogenous proteins is crucial to designing effective antimicrobial agents against Gram-negative bacteria. Here we study, using neutron reflecometry under multiple isotopic contrast conditions, the role of the uncharged sugar groups in the outer core region of lipopolysaccharide (LPS) in protecting the phosphate-rich inner core region from electrostatic interactions with antimicrobial proteins. Models of the asymmetric Gram negative outer membrane on silicon were prepared with phopshatidylcholine (PC) in the inner leaflet (closest to the silicon), whereas rough LPS was used to form the outer leaflet (facing the bulk solution). We show how salt concentration can be used to reversibly alter the binding affinity of a protein antibiotic colicin N (ColN) to the anionic LPS confirming that the interaction is electrostatic in nature. By examining the interaction of ColN with two rough LPS types with different-sized core oligosaccharide regions we demonstrate the role of uncharged sugars in blocking short-range electrostatic interactions between the cationic antibiotics and the vulnerable anionic phosphate groups. PMID:27003358

  2. The Effect of Lipopolysaccharide Core Oligosaccharide Size on the Electrostatic Binding of Antimicrobial Proteins to Models of the Gram Negative Bacterial Outer Membrane

    PubMed Central

    2016-01-01

    Understanding the electrostatic interactions between bacterial membranes and exogenous proteins is crucial to designing effective antimicrobial agents against Gram-negative bacteria. Here we study, using neutron reflecometry under multiple isotopic contrast conditions, the role of the uncharged sugar groups in the outer core region of lipopolysaccharide (LPS) in protecting the phosphate-rich inner core region from electrostatic interactions with antimicrobial proteins. Models of the asymmetric Gram negative outer membrane on silicon were prepared with phopshatidylcholine (PC) in the inner leaflet (closest to the silicon), whereas rough LPS was used to form the outer leaflet (facing the bulk solution). We show how salt concentration can be used to reversibly alter the binding affinity of a protein antibiotic colicin N (ColN) to the anionic LPS confirming that the interaction is electrostatic in nature. By examining the interaction of ColN with two rough LPS types with different-sized core oligosaccharide regions we demonstrate the role of uncharged sugars in blocking short-range electrostatic interactions between the cationic antibiotics and the vulnerable anionic phosphate groups. PMID:27003358

  3. Antibacterial activity of Eisenia fetida andrei coelomic fluid: transcription and translation regulation of lysozyme and proteins evidenced after bacterial infestation.

    PubMed

    Hirigoyenberry, F; Lassalle, F; Lassegues, M

    1990-01-01

    1. After bacterial infestation lysozyme and antibacterial activities are enhanced, peaking at 4 hr and 3 days, respectively. 2. Both humoral defenses require RNA and protein de novo synthesis in response to pathogenic bacteria injection (actinomycin D and cycloheximide experiments). 3. Antibacterial activity exists naturally at some basic level, involving regular translation of stable RNAs. 4. When antibacterial activity reaches its maximum after bacterial injection, proteins responsible for it undergo a turn-over. 5. Lysozyme and antibacterial proteins cannot account for the whole response to bacterial infestation; some cellular defense mechanisms like phagocytosis are involved at the same time. PMID:2331874

  4. Activation of Protein Tyrosine Kinases by Coxiella burnetii: Role in Actin Cytoskeleton Reorganization and Bacterial Phagocytosis

    PubMed Central

    Meconi, Sonia; Capo, Christian; Remacle-Bonnet, Maryse; Pommier, Gilbert; Raoult, Didier; Mege, Jean-Louis

    2001-01-01

    Coxiella burnetii, the agent of Q fever, is an obligate intracellular microorganism that grows in monocytes/macrophages. The internalization of virulent organisms by monocytes is lower than that of avirulent variants and is associated with actin cytoskeleton reorganization. We studied the activation of protein tyrosine kinases (PTKs) by C. burnetii in THP-1 monocytes. Virulent organisms induced early PTK activation and the tyrosine phosphorylation of several endogenous substrates, including Hck and Lyn, two Src-related kinases. PTK activation reflects C. burnetii virulence since avirulent variants were unable to stimulate PTK. We also investigated the role of PTK activation in C. burnetii-stimulated F-actin reorganization. Tyrosine-phosphorylated proteins were colocalized with F-actin inside cell protrusions induced by C. burnetii, and PTK activity was increased in Triton X-100-insoluble fractions. In addition, lavendustin A, a PTK inhibitor, and PP1, a Src kinase inhibitor, prevented C. burnetii-induced cell protrusions and F-actin reorganization. We finally assessed the role of PTK activation in bacterial phagocytosis. Pretreatment of THP-1 cells with lavendustin A and PP1 upregulated the uptake of virulent C. burnetii but had no effect on the phagocytosis of avirulent organisms. Thus, it is likely that PTK activation by C. burnetii negatively regulates bacterial uptake by interfering with cytoskeleton organization. PMID:11254615

  5. Bacterial cell wall components as immunomodulators--II. The bacterial cell wall extract OM-85 BV as unspecific activator, immunogen and adjuvant in mice.

    PubMed

    Bessler, W G; Huber, M; Baier, W

    1997-01-01

    The bacterial extract Broncho-Vaxom used for the prevention and treatment of recurrent respiratory tract infections is an immunomodulator in vitro and in vivo, as determined in a murine model. The extract acts, on the one hand, as macrophage activator and polyclonal B-lymphocyte stimulant. On the other hand, after repeated intraperitoneal or oral immunizations, the extract is immunogenic, inducing serum IgG binding to the bacterial strains used for the preparation of the extract. On bacteria, the sera recognize the cell wall components porin, lipoprotein/lipopeptide and murein. The bacterial extract also exhibits adjuvant properties when applied in mixture with antigens, such as TNP-BSA or an influenza vaccine preparation. The unspecific and the immunospecific stimulatory effect of the extract as well as its adjuvant properties could be of importance for understanding its therapeutic effect. PMID:9637353

  6. Lipid biomarkers and bacterial lipase activities as indicators of organic matter and bacterial dynamics in contrasted regimes at the DYFAMED site, NW Mediterranean

    NASA Astrophysics Data System (ADS)

    Bourguet, Nicolas; Goutx, Madeleine; Ghiglione, Jean-François; Pujo-Pay, Mireille; Mével, Geneviève; Momzikoff, André; Mousseau, Laure; Guigue, Catherine; Garcia, Nicole; Raimbault, Patrick; Pete, Romain; Oriol, Louise; Lefèvre, Dominique

    2009-08-01

    This study investigated the relationships between dissolved organic matter (DOM) composition and bacterial dynamics on short time scale during spring mesotrophic (March 2003) and summer oligotrophic (June 2003) regimes, in a 0-500 m depth water column with almost no advection, at the DYFAMED site, NW Mediterranean. DOM was characterized by analyzing dissolved organic carbon (DOC), colored dissolved organic matter (CDOM) and lipid class biotracers. Bacterial dynamic was assessed through the measurement of in situ bacterial lipase activity, abundance, production and bacterial community structure. We made the assumption that by coupling the ambient concentration of hydrolysable acyl-lipids with the measurement of their in situ bacterial hydrolysis rates (i.e. the free fatty acids release rate) would provide new insights about bacterial response to change in environmental conditions. The seasonal transition from spring to summer was accompanied by a significant accumulation of excess DOC (+5 μM) (ANOVA, p<0.05, n=8) in the upper layer (0-50 m). In this layer, the free fatty acids release rate to the bacterial carbon demand (BCD) ratio increased from 0.6±0.3 in March to 1.3±1.0 in June (ANOVA, p<0.05, n=8) showing that more uncoupling between the hydrolysis of the acyl-lipids and the BCD occurred during the evolution of the season, and that free fatty acids contributed to the excess DOC. The increase of lipolysis index and CDOM absorbance (from 0.24±0.17 to 0.39±0.13 and from 0.076±0.039 to 0.144±0.068; ANOVA, p<0.05, n=8, respectively), and the higher contribution of triglycerides, wax esters and phospholipids (from <5% to 12-31%) to the lipid pool reflected the change in the DOM quality. In addition to a strong increase of bacterial lipase activity per cell (51.4±29.4-418.3±290.6 Ag C cell -1 h -1), a significant percentage of ribotypes (39%) was different between spring and summer in the deep chlorophyll maximum (DCM) layer in particular, suggesting a shift

  7. Differential influence of instruments in nuclear core activity evaluation by data assimilation

    NASA Astrophysics Data System (ADS)

    Bouriquet, Bertrand; Argaud, Jean-Philippe; Erhard, Patrick; Massart, Sébastien; Ponçot, Angélique; Ricci, Sophie; Thual, Olivier

    2011-01-01

    The global neutronic activity fields of a nuclear core can be reconstructed using data assimilation. Indeed, data assimilation allows to combine both measurements from instruments and information from a model, to evaluate the best possible neutronic activity within the core. We present and apply a specific procedure which evaluates the influence of measures by adding or removing instruments in a given measurement network (possibly empty). The study of various network configurations for the instruments in the nuclear core establishes that the influence of the instruments depends both on the independent instrumentation location and on the chosen network.

  8. Antimicrobial Activity of Common Mouthwash Solutions on Multidrug-Resistance Bacterial Biofilms

    PubMed Central

    Masadeh, Majed M.; Gharaibeh, Shadi F.; Alzoubi, Karem H.; Al-Azzam, Sayer I.; Obeidat, Wasfi M.

    2013-01-01

    Background Periodontal bacteria occur in both planktonic and biofilm forms. While poor oral hygiene leads to accumulation of bacteria, reducing these microbes is the first step toward good oral hygiene. This is usually achieved through the use of mouthwash solutions. However, the exact antibacterial activity of mouthwash solution, especially when bacteria form biofilms, is yet to be determined. In this study, we evaluated the antibacterial activity of common mouthwash solutions against standard bacteria in their planktonic and biofilm states. Methods Standard bacterial strains were cultured, and biofilm were formrd. Thereafter, using standard method for determination of minimum inhibitory concentrations (MIC) values of various mouthwash solutions were determined. Results Results show that common mouthwash solutions have variable antibacterial activity depending on their major active components. Only mouthwash solutions containing chlorohexidine gluconate or cetylpyridinum chloride exhibited activity against majority, but not all tested bacterial strains in their biofilm state. Additionally, bacteria are generally less susceptible to all mouthwash solutions in their biofilm as compared to planktonic state. Conclusions While mouthwash solutions have variable antibacterial activity, bacteria in their biofilm state pose a challenge to dental hygiene/care where bacteria become not susceptible to majority of available mouthwash solutions. PMID:23976912

  9. Surface activation of graphene oxide nanosheets by ultraviolet irradiation for highly efficient anti-bacterials

    NASA Astrophysics Data System (ADS)

    Veerapandian, Murugan; Zhang, Linghe; Krishnamoorthy, Karthikeyan; Yun, Kyusik

    2013-10-01

    A comprehensive investigation of anti-bacterial properties of graphene oxide (GO) and ultraviolet (UV) irradiated GO nanosheets was carried out. Microscopic characterization revealed that the GO nanosheet-like structures had wavy features and wrinkles or thin grooves. Fundamental surface chemical states of GO nanosheets (before and after UV irradiation) were investigated using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Minimum inhibitory concentration (MIC) results revealed that UV irradiated GO nanosheets have more pronounced anti-bacterial behavior than GO nanosheets and standard antibiotic, kanamycin. The MIC of UV irradiated GO nanosheets was 0.125 μg ml-1 for Escherichia coli and Salmonella typhimurium, 0.25 μg ml-1 for Bacillus subtilis and 0.5 μg ml-1 for Enterococcus faecalis, ensuring its potential as an anti-infective agent for controlling the growth of pathogenic bacteria. The minimum bactericidal concentration of normal GO nanosheets was determined to be two-fold higher than its corresponding MIC value, indicating promising bactericidal activity. The mechanism of anti-bacterial action was evaluated by measuring the enzymatic activity of β-d-galactosidase for the hydrolysis of o-nitrophenol-β-d-galactopyranoside.

  10. Targeting Bacterial Cell Wall Peptidoglycan Synthesis by Inhibition of Glycosyltransferase Activity.

    PubMed

    Mesleh, Michael F; Rajaratnam, Premraj; Conrad, Mary; Chandrasekaran, Vasu; Liu, Christopher M; Pandya, Bhaumik A; Hwang, You Seok; Rye, Peter T; Muldoon, Craig; Becker, Bernd; Zuegg, Johannes; Meutermans, Wim; Moy, Terence I

    2016-02-01

    Synthesis of bacterial cell wall peptidoglycan requires glycosyltransferase enzymes that transfer the disaccharide-peptide from lipid II onto the growing glycan chain. The polymerization of the glycan chain precedes cross-linking by penicillin-binding proteins and is essential for growth for key bacterial pathogens. As such, bacterial cell wall glycosyltransferases are an attractive target for antibiotic drug discovery. However, significant challenges to the development of inhibitors for these targets include the development of suitable assays and chemical matter that is suited to the nature of the binding site. We developed glycosyltransferase enzymatic activity and binding assays using the natural products moenomycin and vancomycin as model inhibitors. In addition, we designed a library of disaccharide compounds based on the minimum moenomycin fragment with peptidoglycan glycosyltransferase inhibitory activity and based on a more drug-like and synthetically versatile disaccharide building block. A subset of these disaccharide compounds bound and inhibited the glycosyltransferase enzymes, and these compounds could serve as chemical entry points for antibiotic development. PMID:26358369

  11. Selective enrichment and characterization of a phosphorus-removing bacterial consortium from activated sludge.

    PubMed

    Hollender, J; Dreyer, U; Kornberger, L; Kämpfer, P; Dott, W

    2002-01-01

    Under alternating aerobic/anaerobic conditions and without additional carbon sources, a bacterial consortium consisting initially of 18 bacterial strains was obtained in a sequence batch reactor. The phosphorus removal capability could only be maintained using sterile filtrate of activated sludge as medium. The addition of calcium and magnesium salts, as well as vitamins and trace elements, to autoclaved sterile filtrate of activated sludge was not sufficient to achieve stable phosphorus removal. A further enrichment by subcultivation on solid, agar, freezing, and shortening of the aerobic and anaerobic phases led to a defined bacterial consortium consisting of four strains. On the basis of physiological and chemotaxonomic characterization, and partial 16S rRNA sequencing, one of the organisms was identified as Delftia acidovorans. A further isolate belonged to the Bacillus cereus group, and the third isolate was identified as Microbacterium sp.. The remaining strain seems to represent a new genus within the Flavobacteriaceae. Under continuous chemostat conditions, this consortium was able to remove up to 9.6 mg P/l phosphate in the aerobic phase and released up to 8.5 mg/l in the anaerobic phase. Up to 25 mg P-polyphosphate/g dry mass was stored under aerobic conditions. PMID:11831470

  12. Diversity, antimicrobial and antioxidant activities of culturable bacterial endophyte communities in Aloe vera.

    PubMed

    Akinsanya, Mushafau Adewale; Goh, Joo Kheng; Lim, Siew Ping; Ting, Adeline Su Yien

    2015-12-01

    Twenty-nine culturable bacterial endophytes were isolated from surface-sterilized tissues (root, stem and leaf) of Aloe vera and molecularly characterized to 13 genera: Pseudomonas, Bacillus, Enterobacter, Pantoea, Chryseobacterium, Sphingobacterium, Aeromonas, Providencia, Cedecea, Klebsiella, Cronobacter, Macrococcus and Shigella. The dominant genera include Bacillus (20.7%), Pseudomonas (20.7%) and Enterobacter (13.8%). The crude and ethyl acetate fractions of the metabolites of six isolates, species of Pseudomonas, Bacillus, Chryseobacterium and Shigella, have broad spectral antimicrobial activities against pathogenic Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Salmonella Typhimurium, Proteus vulgaris, Klebsiella pneumoniae, Escherichia coli, Streptococcus pyogenes and Candida albicans, with inhibition zones ranging from 6.0 ± 0.57 to 16.6 ± 0.57 mm. In addition, 80% of the bacterial endophytes produced 1,1-diphenyl-2-picrylhydrazyl (DPPH) with scavenging properties of over 75% when their crude metabolites were compared with ascorbic acid (92%). In conclusion, this study revealed for the first time the endophytic bacteria communities from A. vera (Pseudomonas hibiscicola, Macrococcus caseolyticus, Enterobacter ludwigii, Bacillus anthracis) that produce bioactive compounds with high DPPH scavenging properties (75-88%) and (Bacillus tequilensis, Pseudomonas entomophila, Chryseobacterium indologenes, Bacillus aerophilus) that produce bioactive compounds with antimicrobial activities against bacterial pathogens. Hence, we suggest further investigation and characterization of their bioactive compounds. PMID:26454221

  13. In vitro activity of secnidazole against Atopobium vaginae, an anaerobic pathogen involved in bacterial vaginosis.

    PubMed

    De Backer, E; Dubreuil, L; Brauman, M; Acar, J; Vaneechoutte, M

    2010-05-01

    Bacterial vaginosis is a polymicrobial syndrome. The most important marker for bacterial vaginosis is the presence of Gardnerella vaginalis and Atopobium vaginae. In this study, the in vitro susceptibilities to metronidazole and secnidazole of 16 strains of A. vaginae were tested with the agar dilution method. We observed an MIC range for metronidazole of 4-64 mg/L (MIC(50), 8 mg/L; MIC(90), 32 mg/L) and an MIC range for secnidazole of 4-128 mg/L (MIC(50), 16 mg/L; MIC(90), 64 mg/L). According to these findings, we can conclude that the activity of secnidazole is similar to that of metronidazole. PMID:19548924

  14. Human-restricted bacterial pathogens block shedding of epithelial cells by stimulating integrin activation.

    PubMed

    Muenzner, Petra; Bachmann, Verena; Zimmermann, Wolfgang; Hentschel, Jochen; Hauck, Christof R

    2010-09-01

    Colonization of mucosal surfaces is the key initial step in most bacterial infections. One mechanism protecting the mucosa is the rapid shedding of epithelial cells, also termed exfoliation, but it is unclear how pathogens counteract this process. We found that carcinoembryonic antigen (CEA)-binding bacteria colonized the urogenital tract of CEA transgenic mice, but not of wild-type mice, by suppressing exfoliation of mucosal cells. CEA binding triggered de novo expression of the transforming growth factor receptor CD105, changing focal adhesion composition and activating beta1 integrins. This manipulation of integrin inside-out signaling promotes efficient mucosal colonization and represents a potential target to prevent or cure bacterial infections. PMID:20813953

  15. Effects of Bacterial Microflora of the Lower Digestive Tract of Free-Range Waterfowl on Influenza Virus Activation

    PubMed Central

    King, Marcus D.; Guentzel, M. Neal; Arulanandam, Bernard P.; Bodour, Adria A.; Brahmakshatriya, Vinayak; Lupiani, Blanca; Chambers, James P.

    2011-01-01

    Proteolytic cleavage activation of influenza virus hemagglutinin (HA0) is required for cell entry via receptor-mediated endocytosis. Despite numerous studies describing bacterial protease-mediated influenza A viral activation in mammals, very little is known about the role of intestinal bacterial flora of birds in hemagglutinin cleavage/activation. Therefore, the cloaca of wild waterfowl was examined for (i) representative bacterial types and (ii) their ability to cleave in a “trypsin-like” manner the precursor viral hemagglutinin molecule (HA0). Using radiolabeled HA0, bacterial secretion-mediated trypsin-like conversion of HA0 to HA1 and HA2 peptide products was observed to various degrees in 42 of 44 bacterial isolates suggestive of influenza virus activation in the cloaca of wild waterfowl. However, treatment of uncleaved virus with all bacterial isolates gave rise to substantially reduced emergent virus progeny compared with what was expected. Examination of two isolates exhibiting pronounced trypsin-like conversion of HA0 to HA1 and HA2 peptide products and low infectivity revealed lipase activity to be present. Because influenza virus possesses a complex lipid envelope, the presence of lipid hydrolase activity could in part account for the observed less-than-expected level of viable progeny. A thorough characterization of respective isolate protease HA0 hydrolysis products as well as other resident activities (i.e., lipase) is ongoing such that the role of these respective contributors in virus activation/inactivation can be firmly established. PMID:21531837

  16. Bacterial Proteasomes

    PubMed Central

    Jastrab, Jordan B.; Darwin, K. Heran

    2015-01-01

    Interest in bacterial proteasomes was sparked by the discovery that proteasomal degradation is required for the pathogenesis of Mycobacterium tuberculosis, one of the world's deadliest pathogens. Although bacterial proteasomes are structurally similar to their eukaryotic and archaeal homologs, there are key differences in their mechanisms of assembly, activation, and substrate targeting for degradation. In this article, we compare and contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss recent advances in our understanding of how bacterial proteasomes function to influence microbial physiology. PMID:26488274

  17. Molecular characterization of Indian isolate of peanut mottle virus and immunodiagnosis using bacterial expressed core capsid protein.

    PubMed

    Soumya, K; Yogita, M; Prasanthi, Y; Anitha, K; Kishor, P B Kavi; Jain, R K; Mandal, Bikash

    2014-01-01

    Peanut mottle virus (PeMoV), a seed borne potyvirus was recorded in India in 1978, however the virus was not characterized at molecular level. In the present study, an isolate of PeMoV infecting peanut in southern India was characterized based on host reactions and coat protein (CP) gene sequence, which revealed that the Indian isolate was very close to a peanut isolate reported from Israel and distinct from pea isolate reported from USA. The core region of CP gene that contained majority of the predicted epitopes was successfully expressed (1.75 mg/l) in Escherichia coli as a 22 kDa protein. A high titer polyclonal antibody (PAb) to the expressed core CP was produced, which efficiently detected PeMoV. The antiserum was useful in specific detection of PeMoV as it showed negligible cross reactivity with the other potyviruses e.g., peanut stripe virus, potato virus Y, papaya ringspot virus and onion yellow dwarf virus. The PAb was validated in ELISA using 1,169 field and greenhouse samples of peanut which showed 1.85-26.3 % incidence of PeMoV in peanut seed multiplication field during 2011-2012. This is the first report of immunodiagnosis of PeMoV with a PAb to recombinant core CP of PeMoV. PMID:25674600

  18. The antimicrobial activity of honey against common equine wound bacterial isolates.

    PubMed

    Carnwath, R; Graham, E M; Reynolds, K; Pollock, P J

    2014-01-01

    Delayed healing associated with distal limb wounds is a particular problem in equine clinical practice. Recent studies in human beings and other species have demonstrated the beneficial wound healing properties of honey, and medical grade honey dressings are available commercially in equine practice. Equine clinicians are reported to source other non-medical grade honeys for the same purpose. This study aimed to assess the antimicrobial activity of a number of honey types against common equine wound bacterial pathogens. Twenty-nine honey products were sourced, including gamma-irradiated and non-irradiated commercial medical grade honeys, supermarket honeys, and honeys from local beekeepers. To exclude contaminated honeys from the project, all honeys were cultured aerobically for evidence of bacterial contamination. Aerobic bacteria or fungi were recovered from 18 products. The antimicrobial activity of the remaining 11 products was assessed against 10 wound bacteria, recovered from the wounds of horses, including methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa. Eight products were effective against all 10 bacterial isolates at concentrations varying from <2% to 16% (v/v). Overall, the Scottish Heather Honey was the best performing product, and inhibited the growth of all 10 bacterial isolates at concentrations ranging from <2% to 6% (v/v). Although Manuka has been the most studied honey to date, other sources may have valuable antimicrobial properties. Since some honeys were found to be contaminated with aerobic bacteria or fungi, non-sterile honeys may not be suitable for wound treatment. Further assessment of gamma-irradiated honeys from the best performing honeys would be useful. PMID:23962613

  19. Characterization of cellulolytic activities of environmental bacterial consortia from an Argentinian native forest.

    PubMed

    Romano, Nelson; Gioffré, Andrea; Sede, Silvana M; Campos, Eleonora; Cataldi, Angel; Talia, Paola

    2013-08-01

    Cellulolytic activities of three bacterial consortia derived from a forest soil sample from Chaco region, Argentina, were characterized. The phylogenetic analysis of consortia revealed two main highly supported groups including Achromobacter and Pseudomonas genera. All three consortia presented cellulolytic activity. The carboxymethylcellulase (CMCase) and total cellulase activities were studied both quantitatively and qualitatively and optimal enzymatic conditions were characterized and compared among the three consortia. Thermal and pH stability were analyzed. Based on its cellulolytic activity, one consortium was selected for further characterization by zymography. We detected a specific protein of 55 kDa with CMCase activity. In this study, we have shown that these consortia encode for cellulolytic enzymes. These enzymes could be useful for lignocellulosic biomass degradation into simple components and for different industrial applications. PMID:23471693

  20. Germa-gamma-lactones as novel inhibitors of bacterial urease activity.

    PubMed

    Amtul, Zareen; Follmer, Cristian; Mahboob, Sumera; Atta-Ur-Rahman; Mazhar, Muhammad; Khan, Khalid M; Siddiqui, Rafat A; Muhammad, Sajjad; Kazmi, Syed A; Choudhary, Mohammad Iqbal

    2007-05-01

    Organogermanium compounds have been used as pharmacological agents. However, very few reports are available on the synthesis and antibacterial activities of lactones containing organogermaniums. The purpose of the present investigation was to determine the effects of different lactone-substituted organogermaniums on bacterial growth and their urease activity. We report synthesis of 12 germa-gamma-lactones (GeL) and their antimicrobial activities against several bacterial pathogens. Antibacterial action of all GeL was highly selective against Gram-negative bacilli, particularly Proteus mirabilis, an important pathogen infecting the urinary tract. Furthermore, our data indicate that 8-quinoline derivatives were more potent against P. mirabilis than 2-methyl-8-quinoline. For example, the beta-(o-methylphenyl)-gamma,gamma-bis(8-quinolinoxy)germa-gamma-lactone and beta-(o-methoxyphenyl)-gamma,gamma-bis(8-quinolinoxy)germa-gamma-lactone were maximally active with MIC(90) of 61 and 94 microM, respectively. In vitro studies demonstrated a linear correlation between antibacterial activity and inhibition of P. mirabilis urease enzyme. Further kinetic analyses revealed that inhibition occurred in a noncompetitive and concentration-dependent manner with the minimum IC(50) of 31 microM for beta-(o-methoxyphenyl)-gamma,gamma-bis(8-quinolinoxy)germa-gamma-lactone. In conclusion, these findings suggest that GeL have potential to be developed as antimicrobial agents against P. mirabilis infection. PMID:17367756

  1. Surface-Active Agents for Isolation of the Core Component of Avian Myeloblastosis Virus 1

    PubMed Central

    Stromberg, Kurt

    1972-01-01

    Sixty-one surface-active agents were evaluated in a procedure designed to assess their ability to remove the envelope from the core component of avian myeloblastosis virus (AMV). The procedure consisted of centrifugation of intact AMV through a series of sucrose gradients each containing an upper layer of agent at one of eight concentrations between 0.01 and 10%. The effectiveness of an agent in producing AMV cores was indicated by (i) the appearance of light-scattering bands in the region of core buoyant density in gradient tubes; (ii) the range of surfactant concentration over which these bands appeared; and (iii) an electron microscopy assessment by the negative-staining technique of the relative proportion of core to non-core material in each of these bands. Six nonionic surfactants were selected by this screening method for comparison in regard to recovery of core protein and endogenous ribonucleic acid (RNA)-dependent deoxyribonucleic acid (DNA) polymerase activity, as well as further morphologic evaluation by electron microscopy. The nonionic surfactants of the polyoxyethylene alcohol class (particularly, Sterox SL) were most effective. Nonionic surfactants of the polyoxyethylene alkylphenol class (particularly, Nonidet P-40) were also effective. Sterox SL and Nonidet P-40 each gave a more than fivefold increase in specific activity of endogenous RNA-dependent DNA polymerase, and each gave a low recovery of core protein. Sterox SL did not interfere to the extent that Nonidet P-40 did in procedures which involved spectrophotometric assay at 260 nm. The use of Sterox SL resulted in the least envelope contamination of core preparations by electron microscopy examination, the most recovery of protein and endogenous RNA-dependent DNA polymerase activity, and a core buoyant density in sucrose of 1.27 g/ml. Images PMID:4112071

  2. Comparison of Hemagglutination and Hemolytic Activity of Various Bacterial Clinical Isolates Against Different Human Blood Groups

    PubMed Central

    HRV, Rajkumar; Devaki, Ramakrishna

    2016-01-01

    Among the various pathogenic determinants shown by microorganisms hemagglutination and hemolysin production assume greater significance in terms of laboratory identification. This study evaluated the hemagglutination and hemolytic activity of various bacterial isolates against different blood groups. One hundred and fifty bacterial strains, isolated from clinical specimens like urine, pus, blood, and other body fluids were tested for their hemagglutinating and hemolytic activity against human A, B, AB, and O group red blood cells. Among the 150 isolates 81 were Escherichia coli, 18 were Klebsiella pneumoniae, 19 were Pseudomonas aeruginosa, 10 were Pseudomonas spp, six were Proteus mirabilis, and the rest 16 were Staphylococcus aureus. Nearly 85% of the isolates agglutinated A group cells followed by B and AB group (59.3% and 60.6% respectively). Least number of isolates agglutinated O group cells (38.0%). When the hemolytic activity was tested, out of these 150 isolates 79 (52.6%) hemolyzed A group cells, 61 (40.6%) hemolyzed AB group cells, 46 (30.6%) hemolyzed B group cells, and 57 (38.6%) isolates hemolyzed O group cells. Forty-six percent of the isolates exhibited both hemagglutinating and hemolytic property against A group cells, followed by B and AB group cells (28.6% and 21.3% respectively). Least number of isolates i.e., 32 (21.3%) showed both the properties against O group cells. The isolates showed wide variation in their hemagglutination and hemolytic properties against different combinations of human blood group cells. The study highlights the importance of selection of the type of cells especially when human RBCs are used for studying the hemagglutination and hemolytic activity of bacterial isolates because these two properties are considered as characteristic of pathogenic strains. PMID:27014523

  3. Comparison of Hemagglutination and Hemolytic Activity of Various Bacterial Clinical Isolates Against Different Human Blood Groups.

    PubMed

    Hrv, Rajkumar; Devaki, Ramakrishna; Kandi, Venkataramana

    2016-01-01

    Among the various pathogenic determinants shown by microorganisms hemagglutination and hemolysin production assume greater significance in terms of laboratory identification. This study evaluated the hemagglutination and hemolytic activity of various bacterial isolates against different blood groups. One hundred and fifty bacterial strains, isolated from clinical specimens like urine, pus, blood, and other body fluids were tested for their hemagglutinating and hemolytic activity against human A, B, AB, and O group red blood cells. Among the 150 isolates 81 were Escherichia coli, 18 were Klebsiella pneumoniae, 19 were Pseudomonas aeruginosa, 10 were Pseudomonas spp, six were Proteus mirabilis, and the rest 16 were Staphylococcus aureus. Nearly 85% of the isolates agglutinated A group cells followed by B and AB group (59.3% and 60.6% respectively). Least number of isolates agglutinated O group cells (38.0%). When the hemolytic activity was tested, out of these 150 isolates 79 (52.6%) hemolyzed A group cells, 61 (40.6%) hemolyzed AB group cells, 46 (30.6%) hemolyzed B group cells, and 57 (38.6%) isolates hemolyzed O group cells. Forty-six percent of the isolates exhibited both hemagglutinating and hemolytic property against A group cells, followed by B and AB group cells (28.6% and 21.3% respectively). Least number of isolates i.e., 32 (21.3%) showed both the properties against O group cells. The isolates showed wide variation in their hemagglutination and hemolytic properties against different combinations of human blood group cells. The study highlights the importance of selection of the type of cells especially when human RBCs are used for studying the hemagglutination and hemolytic activity of bacterial isolates because these two properties are considered as characteristic of pathogenic strains. PMID:27014523

  4. Insights into the amplification of bacterial resistance to erythromycin in activated sludge.

    PubMed

    Guo, Mei-Ting; Yuan, Qing-Bin; Yang, Jian

    2015-10-01

    Wastewater treatment plants are significant reservoirs for antimicrobial resistance. However, little is known about wastewater treatment effects on the variation of antibiotic resistance. The shifts of bacterial resistance to erythromycin, a macrolide widely used in human medicine, on a lab-scale activated sludge system fed with real wastewater was investigated from levels of bacteria, community and genes, in this study. The resistance variation of total heterotrophic bacteria was studied during the biological treatment process, based on culture dependent method. The alterations of bacterial community resistant to erythromycin and nine typical erythromycin resistance genes were explored with molecular approaches, including high-throughput sequencing and quantitative polymerase chain reaction. The results revealed that the total heterotrophs tolerance level to erythromycin concentrations (higher than 32 mg/L) was significantly amplified during the activated sludge treatment, with the prevalence increased from 9.6% to 21.8%. High-throughput sequencing results demonstrated an obvious increase of the total heterotrophic bacterial diversity resistant to erythromycin. Proteobacteria and Bacteroidetes were the two dominant phyla in the influent and effluent of the bioreactor. However, the prevalence of Proteobacteria decreased from 76% to 59% while the total phyla number increased greatly from 18 to 29 through activated sludge treatment. The gene proportions of erm(A), mef(E) and erm(D) were greatly amplified after biological treatment. It is proposed that the transfer of antibiotic resistance genes through the variable mixtures of bacteria in the activated sludge might be the reason for the antibiotic resistance amplification. The amplified risk of antibiotic resistance in wastewater treatment needs to be paid more attention. PMID:25957255

  5. Nitride stabilized PtNi core-shell nanocatalyst for high oxygen reduction activity.

    PubMed

    Kuttiyiel, Kurian A; Sasaki, Kotaro; Choi, Yongman; Su, Dong; Liu, Ping; Adzic, Radoslav R

    2012-12-12

    We describe a route to the development of novel PtNiN core-shell catalysts with low Pt content shell and inexpensive NiN core having high activity and stability for the oxygen reduction reaction (ORR). The PtNiN synthesis involves nitriding Ni nanoparticles and simultaneously encapsulating it by 2-4 monolayer-thick Pt shell. The experimental data and the density functional theory calculations indicate nitride has the bifunctional effect that facilitates formation of the core-shell structures and improves the performance of the Pt shell by inducing both geometric and electronic effects. Synthesis of inexpensive NiN cores opens up possibilities for designing of various transition metal nitride based core-shell nanoparticles for a wide range of applications in energy conversion processes. PMID:23194259

  6. The killing activity of microwaves on some non-sporogenic and sporogenic medically important bacterial strains.

    PubMed

    Najdovski, L; Dragas, A Z; Kotnik, V

    1991-12-01

    The killing activity of microwaves of 2450 MHz frequency and 325 W, 650 W and 1400 W power on some bacterial strains was investigated. Vegetative strains of Staphylococcus aureus, Streptococcus pyogenes Group A, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis and spores of Bacillus subtilis and Bacillis stearothermophilus in aqueous suspensions were exposed to 325 W and 650 W waves for different lengths of time. Enterococcus faecalis and spores of B. subtilis and B. stearothermophilus were exposed additionally to 1400 W waves in aqueous and 'dried' suspensions. Vegetative bacteria were promptly killed in 5 min or less, E. faecalis being slightly more resistant. Bacterial spores were only killed in aqueous suspension when a 1400 W setting was used for 10 to 20 min. Bacterial spores adhering to the tube walls after the aqueous suspension was poured out were reduced in number. We assume that the conventional microwave ovens available on the market may be used for a high level of disinfection but not for sterilization, and only then if sufficient water is present. PMID:1686036

  7. Peptidomimetic Small Molecules Disrupt Type IV Secretion System Activity in Diverse Bacterial Pathogens

    PubMed Central

    Shaffer, Carrie L.; Good, James A. D.; Kumar, Santosh; Krishnan, K. Syam; Gaddy, Jennifer A.; Loh, John T.; Chappell, Joseph; Almqvist, Fredrik

    2016-01-01

    ABSTRACT Bacteria utilize complex type IV secretion systems (T4SSs) to translocate diverse effector proteins or DNA into target cells. Despite the importance of T4SSs in bacterial pathogenesis, the mechanism by which these translocation machineries deliver cargo across the bacterial envelope remains poorly understood, and very few studies have investigated the use of synthetic molecules to disrupt T4SS-mediated transport. Here, we describe two synthetic small molecules (C10 and KSK85) that disrupt T4SS-dependent processes in multiple bacterial pathogens. Helicobacter pylori exploits a pilus appendage associated with the cag T4SS to inject an oncogenic effector protein (CagA) and peptidoglycan into gastric epithelial cells. In H. pylori, KSK85 impedes biogenesis of the pilus appendage associated with the cag T4SS, while C10 disrupts cag T4SS activity without perturbing pilus assembly. In addition to the effects in H. pylori, we demonstrate that these compounds disrupt interbacterial DNA transfer by conjugative T4SSs in Escherichia coli and impede vir T4SS-mediated DNA delivery by Agrobacterium tumefaciens in a plant model of infection. Of note, C10 effectively disarmed dissemination of a derepressed IncF plasmid into a recipient bacterial population, thus demonstrating the potential of these compounds in mitigating the spread of antibiotic resistance determinants driven by conjugation. To our knowledge, this study is the first report of synthetic small molecules that impair delivery of both effector protein and DNA cargos by diverse T4SSs. PMID:27118587

  8. Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities.

    PubMed

    Singh, Nischal; Shetye, Gauri S; Zheng, Hewen; Sun, Jiayue; Luk, Yan-Yeung

    2016-01-01

    Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration-dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities. PMID:26511780

  9. The Bacterial Alarmone (p)ppGpp Activates the Type III Secretion System in Erwinia amylovora

    PubMed Central

    Ancona, Veronica; Lee, Jae Hoon; Chatnaparat, Tiyakhon; Oh, Jinrok; Hong, Jong-In

    2015-01-01

    ABSTRACT The hypersensitive response and pathogenicity (hrp) type III secretion system (T3SS) is a key pathogenicity factor in Erwinia amylovora. Previous studies have demonstrated that the T3SS in E. amylovora is transcriptionally regulated by a sigma factor cascade. In this study, the role of the bacterial alarmone ppGpp in activating the T3SS and virulence of E. amylovora was investigated using ppGpp mutants generated by Red recombinase cloning. The virulence of a ppGpp-deficient mutant (ppGpp0) as well as a dksA mutant of E. amylovora was completely impaired, and bacterial growth was significantly reduced, suggesting that ppGpp is required for full virulence of E. amylovora. Expression of T3SS genes was greatly downregulated in the ppGpp0 and dksA mutants. Western blotting showed that accumulations of the HrpA protein in the ppGpp0 and dksA mutants were about 10 and 4%, respectively, of that in the wild-type strain. Furthermore, higher levels of ppGpp resulted in a reduced cell size of E. amylovora. Moreover, serine hydroxamate and α-methylglucoside, which induce amino acid and carbon starvation, respectively, activated hrpA and hrpL promoter activities in hrp-inducing minimal medium. These results demonstrated that ppGpp and DksA play central roles in E. amylovora virulence and indicated that E. amylovora utilizes ppGpp as an internal messenger to sense environmental/nutritional stimuli for regulation of the T3SS and virulence. IMPORTANCE The type III secretion system (T3SS) is a key pathogenicity factor in Gram-negative bacteria. Fully elucidating how the T3SS is activated is crucial for comprehensively understanding the function of the T3SS, bacterial pathogenesis, and survival under stress conditions. In this study, we present the first evidence that the bacterial alarmone ppGpp-mediated stringent response activates the T3SS through a sigma factor cascade, indicating that ppGpp acts as an internal messenger to sense environmental/nutritional stimuli for

  10. Core-shell Au@Pd nanoparticles with enhanced catalytic activity for oxygen reduction reaction via core-shell Au@Ag/Pd constructions

    PubMed Central

    Chen, Dong; Li, Chengyin; Liu, Hui; Ye, Feng; Yang, Jun

    2015-01-01

    Core-shell nanoparticles often exhibit improved catalytic properties due to the lattice strain created in these core-shell particles. Herein, we demonstrate the synthesis of core-shell Au@Pd nanoparticles from their core-shell Au@Ag/Pd parents. This strategy begins with the preparation of core-shell Au@Ag nanoparticles in an organic solvent. Then, the pure Ag shells are converted into the shells made of Ag/Pd alloy by galvanic replacement reaction between the Ag shells and Pd2+ precursors. Subsequently, the Ag component is removed from the alloy shell using saturated NaCl solution to form core-shell Au@Pd nanoparticles with an Au core and a Pd shell. In comparison with the core-shell Au@Pd nanoparticles upon directly depositing Pd shell on the Au seeds and commercial Pd/C catalysts, the core-shell Au@Pd nanoparticles via their core-shell Au@Ag/Pd templates display superior activity and durability in catalyzing oxygen reduction reaction, mainly due to the larger lattice tensile effect in Pd shell induced by the Au core and Ag removal. PMID:26144550

  11. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery

    NASA Astrophysics Data System (ADS)

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-01

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

  12. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery.

    PubMed

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-22

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form. PMID:24164775

  13. The presence and role of bacterial quorum sensing in activated sludge

    PubMed Central

    Chong, Grace; Kimyon, Onder; Rice, Scott A.; Kjelleberg, Staffan; Manefield, Mike

    2012-01-01

    Summary Activated sludge used for wastewater treatment globally is composed of a high‐density microbial community of great biotechnological significance. In this study the presence and purpose of quorum sensing via N‐acylated‐l‐homoserine lactones (AHLs) in activated sludge was explored. The presence of N‐heptanoyl‐l‐homoserine lactone in organic extracts of sludge was demonstrated along with activation of a LuxR‐based AHL monitor strain deployed in sludge, indicating AHL‐mediated gene expression is active in sludge flocculates but not in the bulk aqueous phase. Bacterial isolates from activated sludge were screened for AHL production and expression of phenotypes commonly but not exclusively regulated by AHL‐mediated gene transcription. N‐acylated‐l‐homoserine lactone and exoenzyme production were frequently observed among the isolates. N‐acylated‐l‐homoserine lactone addition to sludge upregulated chitinase activity and an AHL‐ and chitinase‐producing isolate closely related to Aeromonas hydrophila was shown to respond to AHL addition with upregulation of chitinase activity. N‐acylated‐l‐homoserine lactones produced by this strain were identified and genes ahyI/R and chiA, encoding AHL production and response and chitinase activity respectively, were sequenced. These experiments provide insight into the relationship between AHL‐mediated gene expression and exoenzyme activity in activated sludge and may ultimately create opportunities to improve sludge performance. PMID:22583685

  14. The Majority of In Vitro Macrophage Activation Exhibited by Extracts of Some Immune Enhancing Botanicals is Due to Bacterial Lipoproteins and Lipopolysaccharides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have identified potent monocyte/macrophage activating bacterial lipoproteins within commonly used immune enhancing botanicals such as Echinacea, American ginseng and alfalfa sprouts. These bacterial lipoproteins, along with lipopolysaccharides, were substantially more potent than other bacteriall...

  15. Effects of Fertilization and Sampling Time on Composition and Diversity of Entire and Active Bacterial Communities in German Grassland Soils

    PubMed Central

    Herzog, Sarah; Wemheuer, Franziska; Wemheuer, Bernd; Daniel, Rolf

    2015-01-01

    Soil bacteria are major players in driving and regulating ecosystem processes. Thus, the identification of factors shaping the diversity and structure of these communities is crucial for understanding bacterial-mediated processes such as nutrient transformation and cycling. As most studies only target the entire soil bacterial community, the response of active community members to environmental changes is still poorly understood. The objective of this study was to investigate the effect of fertilizer application and sampling time on structure and diversity of potentially active (RNA-based) and the entire (DNA-based) bacterial communities in German grassland soils. Analysis of more than 2.3 million 16S rRNA transcripts and gene sequences derived from amplicon-based sequencing of 16S rRNA genes revealed that fertilizer application and sampling time significantly altered the diversity and composition of entire and active bacterial communities. Although the composition of both the entire and the active bacterial community was correlated with environmental factors such as pH or C/N ratio, the active community showed a higher sensitivity to environmental changes than the entire community. In addition, functional analyses were performed based on predictions derived from 16S rRNA data. Genes encoding the uptake of nitrate/nitrite, nitrification, and denitrification were significantly more abundant in fertilized plots compared to non-fertilized plots. Hence, this study provided novel insights into changes in dynamics and functions of soil bacterial communities as response to season and fertilizer application. PMID:26694644

  16. Effects of Fertilization and Sampling Time on Composition and Diversity of Entire and Active Bacterial Communities in German Grassland Soils.

    PubMed

    Herzog, Sarah; Wemheuer, Franziska; Wemheuer, Bernd; Daniel, Rolf

    2015-01-01

    Soil bacteria are major players in driving and regulating ecosystem processes. Thus, the identification of factors shaping the diversity and structure of these communities is crucial for understanding bacterial-mediated processes such as nutrient transformation and cycling. As most studies only target the entire soil bacterial community, the response of active community members to environmental changes is still poorly understood. The objective of this study was to investigate the effect of fertilizer application and sampling time on structure and diversity of potentially active (RNA-based) and the entire (DNA-based) bacterial communities in German grassland soils. Analysis of more than 2.3 million 16S rRNA transcripts and gene sequences derived from amplicon-based sequencing of 16S rRNA genes revealed that fertilizer application and sampling time significantly altered the diversity and composition of entire and active bacterial communities. Although the composition of both the entire and the active bacterial community was correlated with environmental factors such as pH or C/N ratio, the active community showed a higher sensitivity to environmental changes than the entire community. In addition, functional analyses were performed based on predictions derived from 16S rRNA data. Genes encoding the uptake of nitrate/nitrite, nitrification, and denitrification were significantly more abundant in fertilized plots compared to non-fertilized plots. Hence, this study provided novel insights into changes in dynamics and functions of soil bacterial communities as response to season and fertilizer application. PMID:26694644

  17. In vitro anti-biofilm and anti-bacterial activity of Junceella juncea for its biomedical application

    PubMed Central

    Kumar, P; Selvi, S Senthamil; Govindaraju, M

    2012-01-01

    Objective To investigate the anti-biofilm and anti-bacterial activity of Junceella juncea (J. juncea) against biofilm forming pathogenic strains. Methods Gorgonians were extracted with methanol and analysed with fourier transform infrared spectroscopy. Biofilm forming pathogens were identified by Congo red agar supplemented with sucrose. A quantitative spectrophotometric method was used to monitor in vitro biofilm reduction by microtitre plate assay. Anti-bacterial activity of methanolic gorgonian extract (MGE) was carried out by disc diffusion method followed by calculating the percentage of increase with crude methanol (CM). Results The presence of active functional group was exemplified by FT-IR spectroscopy. Dry, black, crystalline colonies confirm the production of extracellular polymeric substances responsible for biofilm formation in Congo red agar. MGE exhibited potential anti-biofilm activity against all tested bacterial strains. The anti-bacterial activity of methanolic extract was comparably higher in Salmonella typhii followed by Escherichia coli, Vibrio cholerae and Shigella flexneri. The overall percentage of increase was higher by 50.2% to CM. Conclusions To conclude, anti-biofilm and anti-bacterial efficacy of J. juncea is impressive over biofilm producing pathogens and are good source for novel anti-bacterial compounds. PMID:23593571

  18. Bacterial pollution, activity and heterotrophic diversity of the northern part of the Aegean Sea, Turkey.

    PubMed

    Çiftçi Türetken, Pelin S; Altuğ, Gülşen

    2016-02-01

    Isolation and characterization studies of marine heterotrophic bacteria are important to describe and understand eco-metobolism of the marine environments. In this study, diversity and community structures of the culturable heterotrophic bacteria, metabollicaly active bacteria and bacterial pollution in the coastal and offshore areas of Gökçeada Island, in the Northern Aegean Sea, Turkey were investigated from March 2012 to November 2013. The primary hydrographic parameters were recorded in situ. The frequency of the metabolically active bacteria was determined by using a modified staining technique. The indicator bacteria were determined by using membrane filtration technique; 126 bacteria isolates, 24 of them first records for this region, were identified using an automated micro-identification system, VITEK2 Compact30. The results showed that detected bacterial community profiles were significantly different when compared with previous studies conducted in polluted marine areas of Turkey. High frequency of faecal bacteria detected at station 2 indicated that increasing human activities and terrestrial pollution sources are shaping factors for possible risks, regarding recreational uses of this region, in the summer seasons. PMID:26832724

  19. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    NASA Astrophysics Data System (ADS)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  20. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    PubMed Central

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-01-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction. PMID:25008009

  1. Role of liquid membrane phenomenon in the anti-bacterial activity of Cefuroxime Sodium

    PubMed Central

    Nagesh, C.; Shankaraiah, M. M.; Venkatesh, J. S.; Setty, S. Ramachandra

    2010-01-01

    The role of liquid membrane phenomenon has been studied in the anti bacterial activity of cephalosporins i.e. Cefuroxime sodium. In our earlier publication [1] it was reported that hydraulic permeability data obtained to demonstrate the existence of liquid membrane in series with supporting membrane generated by Cefuroxime sodium. Transport of selected permeants (glucose, PABA, glycine, and ions like Mg++, NH4+, PO4-, Ca++, Na+, K+ and Cl-) through liquid membrane generated by Cefuroxime sodium in series with supporting membrane has been studied. The results indicated that the liquid membrane generated by Cefuroxime sodium inhibit the transport of various essential bio-molecules and permeants in to the cell. This modification in permeability of different permeants in the presence of the liquid membranes is likely to play significant role in the biological actions of Cefuroxime sodium. The anti-bacterial activity of Cefuroxime sodium further confirmed that the generation of liquid membrane by Cefuroxime sodium is also contributing for the antibacterial activity of them. PMID:24825969

  2. Staphylococcal Enterotoxin B Primes Cytokine Secretion and Lytic Activity in Response to Native Bacterial Antigens

    PubMed Central

    Mason, Kevin M.; Dryden, Tricia D.; Bigley, Nancy J.; Fink, Pamela S.

    1998-01-01

    Superantigens stimulate T-lymphocyte proliferation and cytokine production, but the effects of superantigen exposure on cell function within a complex, highly regulated immune response remain to be determined. In this study, we demonstrate that superantigen exposure significantly alters the murine host response to bacterial antigens in an in vitro coculture system. Two days after exposure to the superantigen staphylococcal enterotoxin B, splenocytes cultured with Streptococcus mutans produced significantly greater amounts of gamma interferon (IFN-γ) and interleukin-12 than did sham-injected controls. The majority of IFN-γ production appeared to be CD8+ T-cell derived since depletion of this cell type dramatically reduced the levels of IFN-γ. To study host cell damage that may occur following superantigen exposure, we analyzed cytotoxicity to “bystander” fibroblast cells cultured with splenocytes in the presence of bacterial antigens. Prior host exposure to staphylococcal enterotoxin B significantly enhanced fibroblast cytotoxicity in the presence of bacteria. Neutralization of IFN-γ decreased the amount of cytotoxicity observed. However, a greater reduction was evident when splenocyte-bacterium cocultures were separated from the bystander cell monolayer via a permeable membrane support. Increased cytotoxicity appears to be primarily dependent upon cell-cell contact. Collectively, these data indicate that overproduction of inflammatory cytokines may alter the activity of cytotoxic immune cells. Superantigen exposure exacerbates cytokine production and lytic cell activity when immune cells encounter bacteria in vitro and comparable activities could possibly occur in vivo. PMID:9784507

  3. Bactericidal/permeability-increasing protein promotes complement activation for neutrophil-mediated phagocytosis on bacterial surface

    PubMed Central

    Nishimura, H; Gogami, A; Miyagawa, Y; Nanbo, A; Murakami, Y; Baba, T; Nagasawa, S

    2001-01-01

    The neutrophil bactericidal/permeability-increasing protein (BPI) has both bactericidal and lipopolysaccharide-neutralizing activities. The present study suggests that BPI also plays an important role in phagocytosis of Escherichia coli by neutrophils through promotion of complement activation on the bacterial surface. Flow cytometric analysis indicated that fluorescein-labelled E. coli treated with BPI were phagocytosed in the presence of serum at two- to five-fold higher levels than phagocytosis of the bacteria without the treatment. In contrast, phagocytosis of the fluoresceined bacteria with or without treatment by BPI did not occur at all in the absence of serum. The phagocytosis stimulated by BPI and serum was dose-dependent. The effect of BPI on phagocytosis in the presence of serum was not observed on Gram-positive bacteria (Staphylococcus aureus). Interestingly, the complement C3b/iC3b fragments were deposited onto the bacterial surface also as a function of the BPI concentration under conditions similar to those for phagocytosis. Furthermore, the BPI-promoted phagocytosis was blocked completely by anti-C3 F(ab′)2 and partially by anti-complement receptor (CR) type 1 and/or anti-CR type 3. These findings suggest that BPI accelerates complement activation to opsonize bacteria with complement-derived fragments, leading to stimulation of phagocytosis by neutrophils via CR(s). PMID:11529944

  4. Isolation of an Active Catalytic Core of Streptococcus downei MFe28 GTF-I Glucosyltransferase

    PubMed Central

    Monchois, Vincent; Arguello-Morales, Martha; Russell, Roy R. B.

    1999-01-01

    Truncated variants of GTF-I from Streptococcus downei MFe28 were purified by means of a histidine tag. Sequential deletions showed that the C-terminal domain was not directly involved in the catalytic process but was required for primer activation. A fully active catalytic core of only 100 kDa was isolated. PMID:10094712

  5. Unexpected reactivity and mechanism of carboxamide activation in bacterial N-linked protein glycosylation.

    PubMed

    Lizak, Christian; Gerber, Sabina; Michaud, Gaëlle; Schubert, Mario; Fan, Yao-Yun; Bucher, Monika; Darbre, Tamis; Aebi, Markus; Reymond, Jean-Louis; Locher, Kaspar P

    2013-01-01

    The initial glycan transfer in asparagine-linked protein glycosylation is catalysed by the integral membrane enzyme oligosaccharyltransferase (OST). Here we study the mechanism of the bacterial PglB protein, a single-subunit OST, using chemically synthesized acceptor peptide analogues. We find that PglB can glycosylate not only asparagine but also glutamine, homoserine and the hydroxamate Asp(NHOH), although at much lower rates. In contrast, N-methylated asparagine or 2,4-diaminobutanoic acid (Dab) are not glycosylated. We find that of the various peptide analogues, only asparagine- or Dab-containing peptides bind tightly to PglB. Glycopeptide products are unable to bind, providing the driving force of product release. We find no suitably positioned residues near the active site of PglB that can activate the acceptor asparagine by deprotonation, making a general base mechanism unlikely and leaving carboxamide twisting as the most likely mechanistic proposal for asparagine activation. PMID:24149797

  6. Activation of the prophenoloxidase cascade and initiation of nodule formation in locusts by bacterial lipopolysaccharides.

    PubMed

    Ratcliffe, N A; Brookman, J L; Rowley, A F

    1991-01-01

    The activation of the prophenoloxidase (proPO) system of the locusts, Schistocerca gregaria and Locusta migratoria, by several bacterial lipopolysaccharides (LPS) is described. Activation of proPO by LPS occurred only in the presence of whole blood homogenates and not with hemocyte lysate preparations alone. Levels of phenoloxidase generated by the different LPSs in vitro were also correlated with numbers of nodules formed in vivo by injection of these LPSs. This further strengthens the evidence for the involvement of proPO activation in the insect cellular defenses. Finally, the wisdom in using anticoagulants in order to stabilize fragile hemocytes in studies on the proPO system is discussed. PMID:1904828

  7. Modulating antibiotic activity towards respiratory bacterial pathogens by co-medications: a multi-target approach.

    PubMed

    Vandevelde, Nathalie M; Tulkens, Paul M; Van Bambeke, Françoise

    2016-07-01

    Non-antibiotic drugs can modulate bacterial physiology and/or antibiotic activity, opening perspectives for innovative therapeutic strategies. Focusing on respiratory pathogens and considering in vitro, in vivo, and clinical data, here we examine the effect of these drugs on the expression of resistance mechanisms, biofilm formation, and intracellular survival, as well as their influence on the activity of antibiotics on bacteria. Beyond the description of the effects observed, we also comment on concentrations that are active and discuss the mechanisms of drug-drug or drug-target interactions. This discussion should be helpful in defining useful targets for adjuvant therapy and establishing the corresponding pharmacophores for further drug fine-tuning. PMID:27094105

  8. In Search of Alternative Antibiotic Drugs: Quorum-Quenching Activity in Sponges and their Bacterial Isolates.

    PubMed

    Saurav, Kumar; Bar-Shalom, Rinat; Haber, Markus; Burgsdorf, Ilia; Oliviero, Giorgia; Costantino, Valeria; Morgenstern, David; Steindler, Laura

    2016-01-01

    Owing to the extensive development of drug resistance in pathogens against the available antibiotic arsenal, antimicrobial resistance is now an emerging major threat to public healthcare. Anti-virulence drugs are a new type of therapeutic agent aiming at virulence factors rather than killing the pathogen, thus providing less selective pressure for evolution of resistance. One promising example of this therapeutic concept targets bacterial quorum sensing (QS), because QS controls many virulence factors responsible for bacterial infections. Marine sponges and their associated bacteria are considered a still untapped source for unique chemical leads with a wide range of biological activities. In the present study, we screened extracts of 14 sponge species collected from the Red and Mediterranean Sea for their quorum-quenching (QQ) potential. Half of the species showed QQ activity in at least 2 out of 3 replicates. Six out of the 14 species were selected for bacteria isolation, to test for QQ activity also in isolates, which, once cultured, represent an unlimited source of compounds. We show that ≈20% of the isolates showed QQ activity based on a Chromobacterium violaceum CV026 screen, and that the presence or absence of QQ activity in a sponge extract did not correlate with the abundance of isolates with the same activity from the same sponge species. This can be explained by the unknown source of QQ compounds in sponge-holobionts (host or symbionts), and further by the possible non-symbiotic nature of bacteria isolated from sponges. The potential symbiotic nature of the isolates showing QQ activity was tested according to the distribution and abundance of taxonomically close bacterial Operational Taxonomic Units (OTUs) in a dataset including 97 sponge species and 178 environmental samples (i.e., seawater, freshwater, and marine sediments). Most isolates were found not to be enriched in sponges and may simply have been trapped in the filtration channels of the

  9. In Search of Alternative Antibiotic Drugs: Quorum-Quenching Activity in Sponges and their Bacterial Isolates

    PubMed Central

    Saurav, Kumar; Bar-Shalom, Rinat; Haber, Markus; Burgsdorf, Ilia; Oliviero, Giorgia; Costantino, Valeria; Morgenstern, David; Steindler, Laura

    2016-01-01

    Owing to the extensive development of drug resistance in pathogens against the available antibiotic arsenal, antimicrobial resistance is now an emerging major threat to public healthcare. Anti-virulence drugs are a new type of therapeutic agent aiming at virulence factors rather than killing the pathogen, thus providing less selective pressure for evolution of resistance. One promising example of this therapeutic concept targets bacterial quorum sensing (QS), because QS controls many virulence factors responsible for bacterial infections. Marine sponges and their associated bacteria are considered a still untapped source for unique chemical leads with a wide range of biological activities. In the present study, we screened extracts of 14 sponge species collected from the Red and Mediterranean Sea for their quorum-quenching (QQ) potential. Half of the species showed QQ activity in at least 2 out of 3 replicates. Six out of the 14 species were selected for bacteria isolation, to test for QQ activity also in isolates, which, once cultured, represent an unlimited source of compounds. We show that ≈20% of the isolates showed QQ activity based on a Chromobacterium violaceum CV026 screen, and that the presence or absence of QQ activity in a sponge extract did not correlate with the abundance of isolates with the same activity from the same sponge species. This can be explained by the unknown source of QQ compounds in sponge-holobionts (host or symbionts), and further by the possible non-symbiotic nature of bacteria isolated from sponges. The potential symbiotic nature of the isolates showing QQ activity was tested according to the distribution and abundance of taxonomically close bacterial Operational Taxonomic Units (OTUs) in a dataset including 97 sponge species and 178 environmental samples (i.e., seawater, freshwater, and marine sediments). Most isolates were found not to be enriched in sponges and may simply have been trapped in the filtration channels of the

  10. Complement activation and cytokine response by BioProtein, a bacterial single cell protein.

    PubMed

    Sikkeland, L I B; Thorgersen, E B; Haug, T; Mollnes, T E

    2007-04-01

    The bacterial single cell protein (BSCP), BioProtein, is dried bacterial mass derived from fermentation of the gram negative bacteria Methylococcus capsulatus, used for animal and fish feed. Workers in this industry suffer frequently from pulmonary and systemic symptoms which may be induced by an inflammatory reaction. The aim of the present study was to examine the effect of BSCP on inflammation in vitro as evaluated by complement activation and cytokine production. Human serum was incubated with BSCP and complement activation products specific for all pathways were detected by enzyme-linked immunosorbent assay (ELISA). Human whole blood anti-coagulated with lepirudin was incubated with BSCP and a panel of 27 biological mediators was measured using multiplex technology. BSCP induced a dose-dependent complement activation as revealed by a pronounced increase in alternative and terminal pathway activation (fivefold and 20-fold, respectively) at doses from 1 microg BSCP/ml serum and a similar, but less extensive (two- to fourfold) increase in activation of the lectin and classical pathways at doses from 100 and 1000 microg BSCP/ml serum, respectively. Similarly, BSCP induced a dose-dependent production of a number of cytokines, chemokines and growth factors in human whole blood. At doses as low as 0 x 05-0 x 5 microg BSCP/ml blood a substantial increase was seen for tumour necrosis factor (TNF)-alpha, interleukin (IL)-1-beta, IL-6, interferon (IFN)-gamma, IL-8, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, IL-4, IL-9, IL-17, IL-1Ra, granulocyte-colony-stimulating factor (G-CSF) and vascular endothelial growth factor (VEGF). Thus, BSCP induced a substantial activation of all three initial complement pathways as well as a pronounced cytokine response in vitro, indicating a potent inflammatory property of this agent. PMID:17302729

  11. Release of Toll-Like Receptor-2-Activating Bacterial Lipoproteins in Shigella flexneri Culture Supernatants

    PubMed Central

    Aliprantis, Antonios O.; Weiss, David S.; Radolf, Justin D.; Zychlinsky, Arturo

    2001-01-01

    Shigella spp. cause dysentery, a severe form of bloody diarrhea. Apoptosis, or programmed cell death, is induced during Shigella infections and has been proposed to be a key event in the pathogenesis of dysentery. Here, we describe a novel cytotoxic activity in the sterile-culture supernatants of Shigella flexneri. An identical activity was identified in purified S. flexneri endotoxin, defined here as a mixture of lipopolysaccharide (LPS) and endotoxin-associated proteins (EP). Separation of endotoxin into EP and LPS revealed the activity to partition exclusively to the EP fraction. Biochemical characterization of S. flexneri EP and culture supernatants, including enzymatic deactivation, reverse-phase high-pressure liquid chromatography analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and a Toll-like receptor-2 (TLR2) activation assay, indicates that the cytotoxic component is a mixture of bacterial lipoproteins (BLP). We show that biologically active BLP are liberated into culture supernatants of actively growing S. flexneri. In addition, our data indicate that BLP, and not LPS, are the component of endotoxin of gram-negative organisms responsible for activating TLR2. The activation of apoptosis by BLP shed from S. flexneri is discussed as a novel aspect of the interaction of bacteria with the host. PMID:11553567

  12. Transcriptional activity around bacterial cell death reveals molecular biomarkers for cell viability

    PubMed Central

    Kort, Remco; Keijser, Bart J; Caspers, Martien PM; Schuren, Frank H; Montijn, Roy

    2008-01-01

    Background In bacteriology, the ability to grow in selective media and to form colonies on nutrient agar plates is routinely used as a retrospective criterion for the detection of living bacteria. However, the utilization of indicators for bacterial viability-such as the presence of specific transcripts or membrane integrity-would overcome bias introduced by cultivation and reduces the time span of analysis from initiation to read out. Therefore, we investigated the correlation between transcriptional activity, membrane integrity and cultivation-based viability in the Gram-positive model bacterium Bacillus subtilis. Results We present microbiological, cytological and molecular analyses of the physiological response to lethal heat stress under accurately defined conditions through systematic sampling of bacteria from a single culture exposed to gradually increasing temperatures. We identified a coherent transcriptional program including known heat shock responses as well as the rapid expression of a small number of sporulation and competence genes, the latter only known to be active in the stationary growth phase. Conclusion The observed coordinated gene expression continued even after cell death, in other words after all bacteria permanently lost their ability to reproduce. Transcription of a very limited number of genes correlated with cell viability under the applied killing regime. The transcripts of the expressed genes in living bacteria – but silent in dead bacteria-include those of essential genes encoding chaperones of the protein folding machinery and can serve as molecular biomarkers for bacterial cell viability. PMID:19061518

  13. Colorimetric detection of Shewanella oneidensis based on immunomagnetic capture and bacterial intrinsic peroxidase activity

    NASA Astrophysics Data System (ADS)

    Wen, Junlin; Zhou, Shungui; Chen, Junhua

    2014-06-01

    Rapid detection and enumeration of target microorganisms is considered as a powerful tool for monitoring bioremediation process that typically involves cleaning up polluted environments with functional microbes. A novel colorimetric assay is presented based on immunomagnetic capture and bacterial intrinsic peroxidase activity for rapidly detecting Shewanella oneidensis, an important model organism for environmental bioremediation because of its remarkably diverse respiratory abilities. Analyte bacteria captured on the immunomagnetic beads provided a bacterial out-membrane peroxidase-amplified colorimetric readout of the immunorecognition event by oxidizing 3, 3', 5, 5'-tetramethylbenzidine (TMB) in the present of hydrogen peroxide. The high-efficiency of immunomagnetic capture and signal amplification of peroxidase activity offers an excellent detection performance with a wide dynamic range between 5.0 × 103 and 5.0 × 106 CFU/mL toward target cells. Furthermore, this method was demonstrated to be feasible in detecting S. oneidensis cells spiked in environmental samples. The proposed colorimetric assay shows promising environmental applications for rapid detection of target microorganisms.

  14. Nitrate reducing bacterial activity in concrete cells of nuclear waste disposal

    NASA Astrophysics Data System (ADS)

    Alquier, M.; Kassim, C.; Bertron, A.; Rafrafi, Y.; Sablayrolles, C.; Albrecht, A.; Erable, B.

    2013-07-01

    Leaching experiments of solid matrices (bitumen and cement pastes) have been first implemented to define the physicochemical conditions that microorganisms are likely to meet at the bitumen-concrete interface (see the paper of Bertron et al.). Of course, as might be suspected, the cement matrix imposes highly alkaline pH conditions (10 bacterial strains led us to select Halomonas desiderata as a model bacterium capable of catalyzing the reaction of nitrate reduction in these extreme conditions of pH. The denitrifying activity of Halomonas desiderata was quantified in batch bioreactor in the presence of solid matrices and / or leachate from bitumen and cement matrices. Denitrification was relatively fast in the presence of cement matrix (<100 hours) and 2 to 3 times slower in the presence of bituminous matrix. Overall, the presence of solid cement promoted the kinetics of denitrification. The observation of solid surfaces at the end of the experiment revealed the presence of a biofilm of Halomonas desiderata on the cement paste surface. These attached bacteria showed a denitrifying activity comparable to planktonic bacterial culture. On the other side, no colonization of bitumen could be highlighted as either by SEM or epifluorescence microscopy. Now, we are currently developing a continuous experimental bioreactor which should allow us a more rational understanding of the bitumen-cement-microbe interactions.

  15. Bacterial Peptide Recognition and Immune Activation Facilitated by Human Peptide Transporter PEPT2

    PubMed Central

    Swaan, Peter W.; Bensman, Timothy; Bahadduri, Praveen M.; Hall, Mark W.; Sarkar, Anasuya; Bao, Shengying; Khantwal, Chandra M.; Ekins, Sean; Knoell, Daren L.

    2008-01-01

    Microbial detection requires the recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs) that are distributed on the cell surface and within the cytosol. The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family functions as an intracellular PRR that triggers the innate immune response. The mechanism by which PAMPs enter the cytosol to interact with NLRs, particularly muropeptides derived from the bacterial proteoglycan cell wall, is poorly understood. PEPT2 is a proton-dependent transporter that mediates the active translocation of di- and tripeptides across epithelial tissues, including the lung. Using computational tools, we initially established that bacterial dipeptides, particularly γ-D-glutamyl-meso-diaminopimelic acid (γ-iE-DAP), are suitable substrates for PEPT2. We then determined in primary cultures of human upper airway epithelia and transiently transfected CHO-PEPT2 cell lines that γ-iE-DAP uptake was mediated by PEPT2 with an affinity constant of approximately 193 μM, whereas muramyl dipeptide was not transported. Exposure to γ-iE-DAP at the apical surface of differentiated, polarized cultures resulted in activation of the innate immune response in an NOD1- and RIP2-dependent manner, resulting in release of IL-6 and IL-8. Based on these findings we report that PEPT2 plays a vital role in microbial recognition by NLR proteins, particularly with regard to airborne pathogens, thereby participating in host defense in the lung. PMID:18474668

  16. Colorimetric detection of Shewanella oneidensis based on immunomagnetic capture and bacterial intrinsic peroxidase activity

    PubMed Central

    Wen, Junlin; Zhou, Shungui; Chen, Junhua

    2014-01-01

    Rapid detection and enumeration of target microorganisms is considered as a powerful tool for monitoring bioremediation process that typically involves cleaning up polluted environments with functional microbes. A novel colorimetric assay is presented based on immunomagnetic capture and bacterial intrinsic peroxidase activity for rapidly detecting Shewanella oneidensis, an important model organism for environmental bioremediation because of its remarkably diverse respiratory abilities. Analyte bacteria captured on the immunomagnetic beads provided a bacterial out-membrane peroxidase-amplified colorimetric readout of the immunorecognition event by oxidizing 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the present of hydrogen peroxide. The high-efficiency of immunomagnetic capture and signal amplification of peroxidase activity offers an excellent detection performance with a wide dynamic range between 5.0 × 103 and 5.0 × 106 CFU/mL toward target cells. Furthermore, this method was demonstrated to be feasible in detecting S. oneidensis cells spiked in environmental samples. The proposed colorimetric assay shows promising environmental applications for rapid detection of target microorganisms. PMID:24898751

  17. High Frequency and Diversity of Antimicrobial Activities Produced by Nasal Staphylococcus Strains against Bacterial Competitors

    PubMed Central

    Janek, Daniela; Zipperer, Alexander; Kulik, Andreas; Krismer, Bernhard; Peschel, Andreas

    2016-01-01

    The human nasal microbiota is highly variable and dynamic often enclosing major pathogens such as Staphylococcus aureus. The potential roles of bacteriocins or other mechanisms allowing certain bacterial clones to prevail in this nutrient-poor habitat have hardly been studied. Of 89 nasal Staphylococcus isolates, unexpectedly, the vast majority (84%) was found to produce antimicrobial substances in particular under habitat-specific stress conditions, such as iron limitation or exposure to hydrogen peroxide. Activity spectra were generally narrow but highly variable with activities against certain nasal members of the Actinobacteria, Proteobacteria, Firmicutes, or several groups of bacteria. Staphylococcus species and many other Firmicutes were insusceptible to most of the compounds. A representative bacteriocin was identified as a nukacin-related peptide whose inactivation reduced the capacity of the producer Staphylococcus epidermidis IVK45 to limit growth of other nasal bacteria. Of note, the bacteriocin genes were found on mobile genetic elements exhibiting signs of extensive horizontal gene transfer and rearrangements. Thus, continuously evolving bacteriocins appear to govern bacterial competition in the human nose and specific bacteriocins may become important agents for eradication of notorious opportunistic pathogens from human microbiota. PMID:27490492

  18. Gustatory-mediated avoidance of bacterial lipopolysaccharides via TRPA1 activation in Drosophila

    PubMed Central

    Soldano, Alessia; Alpizar, Yeranddy A; Boonen, Brett; Franco, Luis; López-Requena, Alejandro; Liu, Guangda; Mora, Natalia; Yaksi, Emre; Voets, Thomas; Vennekens, Rudi; Hassan, Bassem A; Talavera, Karel

    2016-01-01

    Detecting pathogens and mounting immune responses upon infection is crucial for animal health. However, these responses come at a high metabolic price (McKean and Lazzaro, 2011, Kominsky et al., 2010), and avoiding pathogens before infection may be advantageous. The bacterial endotoxins lipopolysaccharides (LPS) are important immune system infection cues (Abbas et al., 2014), but it remains unknown whether animals possess sensory mechanisms to detect them prior to infection. Here we show that Drosophila melanogaster display strong aversive responses to LPS and that gustatory neurons expressing Gr66a bitter receptors mediate avoidance of LPS in feeding and egg laying assays. We found the expression of the chemosensory cation channel dTRPA1 in these cells to be necessary and sufficient for LPS avoidance. Furthermore, LPS stimulates Drosophila neurons in a TRPA1-dependent manner and activates exogenous dTRPA1 channels in human cells. Our findings demonstrate that flies detect bacterial endotoxins via a gustatory pathway through TRPA1 activation as conserved molecular mechanism. DOI: http://dx.doi.org/10.7554/eLife.13133.001 PMID:27296646

  19. Combined geochemical and electrochemical methodology to quantify corrosion of carbon steel by bacterial activity.

    PubMed

    Schütz, Marta K; Moreira, Rebeca; Bildstein, Olivier; Lartigue, Jean-Eric; Schlegel, Michel L; Tribollet, Bernard; Vivier, Vincent; Libert, Marie

    2014-06-01

    The availability of respiratory substrates, such as H2 and Fe(II,III) solid corrosion products within nuclear waste repository, will sustain the activities of hydrogen-oxidizing bacteria (HOB) and iron-reducing bacteria (IRB). This may have a direct effect on the rate of carbon steel corrosion. This study investigates the effects of Shewanella oneidensis (an HOB and IRB model organism) on the corrosion rate by looking at carbon steel dissolution in the presence of H2 as the sole electron donor. Bacterial effect is evaluated by means of geochemical and electrochemical techniques. Both showed that the corrosion rate is enhanced by a factor of 2-3 in the presence of bacteria. The geochemical experiments indicated that the composition and crystallinity of the solid corrosion products (magnetite and vivianite) are modified by bacteria. Moreover, the electrochemical experiments evidenced that the bacterial activity can be stimulated when H2 is generated in a small confinement volume. In this case, a higher corrosion rate and mineralization (vivianite) on the carbon steel surface were observed. The results suggest that the mechanism likely to influence the corrosion rate is the bioreduction of Fe(III) from magnetite coupled to the H2 oxidation. PMID:24064199

  20. Toll-like receptor 2 activation depends on lipopeptide shedding by bacterial surfactants

    PubMed Central

    Hanzelmann, Dennis; Joo, Hwang-Soo; Franz-Wachtel, Mirita; Hertlein, Tobias; Stevanovic, Stefan; Macek, Boris; Wolz, Christiane; Götz, Friedrich; Otto, Michael; Kretschmer, Dorothee; Peschel, Andreas

    2016-01-01

    Sepsis caused by Gram-positive bacterial pathogens is a major fatal disease but its molecular basis remains elusive. Toll-like receptor 2 (TLR2) has been implicated in the orchestration of inflammation and sepsis but its role appears to vary for different pathogen species and clones. Accordingly, Staphylococcus aureus clinical isolates differ substantially in their capacity to activate TLR2. Here we show that strong TLR2 stimulation depends on high-level production of phenol-soluble modulin (PSM) peptides in response to the global virulence activator Agr. PSMs are required for mobilizing lipoproteins, the TLR2 agonists, from the staphylococcal cytoplasmic membrane. Notably, the course of sepsis caused by PSM-deficient S. aureus is similar in wild-type and TLR2-deficient mice, but TLR2 is required for protection of mice against PSM-producing S. aureus. Thus, a crucial role of TLR2 depends on agonist release by bacterial surfactants. Modulation of this process may lead to new therapeutic strategies against Gram-positive infections. PMID:27470911

  1. Toll-like receptor 2 activation depends on lipopeptide shedding by bacterial surfactants.

    PubMed

    Hanzelmann, Dennis; Joo, Hwang-Soo; Franz-Wachtel, Mirita; Hertlein, Tobias; Stevanovic, Stefan; Macek, Boris; Wolz, Christiane; Götz, Friedrich; Otto, Michael; Kretschmer, Dorothee; Peschel, Andreas

    2016-01-01

    Sepsis caused by Gram-positive bacterial pathogens is a major fatal disease but its molecular basis remains elusive. Toll-like receptor 2 (TLR2) has been implicated in the orchestration of inflammation and sepsis but its role appears to vary for different pathogen species and clones. Accordingly, Staphylococcus aureus clinical isolates differ substantially in their capacity to activate TLR2. Here we show that strong TLR2 stimulation depends on high-level production of phenol-soluble modulin (PSM) peptides in response to the global virulence activator Agr. PSMs are required for mobilizing lipoproteins, the TLR2 agonists, from the staphylococcal cytoplasmic membrane. Notably, the course of sepsis caused by PSM-deficient S. aureus is similar in wild-type and TLR2-deficient mice, but TLR2 is required for protection of mice against PSM-producing S. aureus. Thus, a crucial role of TLR2 depends on agonist release by bacterial surfactants. Modulation of this process may lead to new therapeutic strategies against Gram-positive infections. PMID:27470911

  2. Enhanced antimicrobial activity of peptide-cocktails against common bacterial contaminants of ex vivo stored platelets.

    PubMed

    Mohan, K V K; Rao, S Sainath; Gao, Y; Atreya, C D

    2014-01-01

    Bacterial contamination of blood components such as ex vivo-stored platelets is a major safety risk in transfusion medicine. We have recently shown that synthetic antimicrobial peptides named PD1-PD4 derived from the thrombin-induced human platelet-derived antimicrobial proteins, and repeats of Arg-Trp (RW1-RW5) demonstrate microbicidal activity against selected bacteria and viruses. In the present study, we selected PD3, PD4, RW2, RW3 and RW4 and evaluated each individual peptide and their various combinations to see whether the cocktail regimen enhances the antimicrobial activity above and over the individual peptides. Stored platelet or plasma samples spiked with known titres of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Bacillus cereus were treated with either individual peptides or with peptides in various combinations. Analyses revealed that individual peptides show moderate microbicidal activity (10- to 100-fold reduction) against the tested bacteria relative to their combined regimen. The peptide combinations (RW2 + RW4, RW2 + RW3 + RW4 and PD4 + RW3 + RW4) on the other hand enhanced the microbicidal activity (c.10 000-fold reduction) and revealed a minimal inhibitory concentration of 5 μM. Time-kill kinetics indicated that these three peptide combinations exhibited enhanced antimicrobial activity bringing about a 100-fold reduction of bacterial titres within 20 min of incubation. The present study therefore demonstrates the synergistic effect of antimicrobial peptides when used in combinations and provides a proof-of-concept of its potential application as a molecular tool towards pathogen reduction and further extends the possibility of using peptide combinatorial therapeutics as broad-spectrum antibiotics or as alternatives to combat drug-resistant bacteria. PMID:23926880

  3. Carbon-Supported IrNi Core-Shell Nanoparticles: Synthesis Characterization and Catalytic Activity

    SciTech Connect

    K Sasaki; K Kuttiyiel; L Barrio; D Su; A Frenkel; N Marinkovic; D Mahajan; R Adzic

    2011-12-31

    We synthesized carbon-supported IrNi core-shell nanoparticles by chemical reduction and subsequent thermal annealing in H{sub 2}, and verified the formation of Ir shells on IrNi solid solution alloy cores by various experimental methods. The EXAFS analysis is consistent with the model wherein the IrNi nanoparticles are composed of two-layer Ir shells and IrNi alloy cores. In situ XAS revealed that the Ir shells completely protect Ni atoms in the cores from oxidation or dissolution in an acid electrolyte under elevated potentials. The formation of Ir shell during annealing due to thermal segregation is monitored by time-resolved synchrotron XRD measurements, coupled with Rietveld refinement analyses. The H{sub 2} oxidation activity of the IrNi nanoparticles was found to be higher than that of a commercial Pt/C catalyst. This is predominantly due to Ni-core-induced Ir shell contraction that makes the surface less reactive for IrOH formation, and the resulting more metallic Ir surface becomes more active for H{sub 2} oxidation. This new class of core-shell nanoparticles appears promising for application as hydrogen anode fuel cell electrocatalysts.

  4. Core plasma behavior during sawtooth activities in highly-elongated ohmic/ECH tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Kim, Junghee; Lee, Seung Hun; Turri, G.; Weisen, H.; Choe, W.

    2008-11-01

    MHD instabilities arising from the combination of pressure and current profiles can deform the core plasma shape. The sawtoothing highly-elongated plasma shows various topological behaviors inside the q=1 surface. The irreversible topology-breaking of the core plasma occurs distinctively in highly-elongated ohmic plasma. On the contrary, the topological change does not occur in the ECH plasma under the same shaping factors because the increased conductivity results in the change of the current profile and thus affecting the Mercier criterion. In addition, the topology-breaking depends on the heating position. The ECH on the off-axis or the q=1 surface preserves the core topology during the crash. However, the intense on-axis ECH can change the core topology, which is reversible. The explanation for these activities is given by topological categorization and the stability analyses of the kink mode with pressure and current profiles.

  5. SGLT1 activity in lung alveolar cells of diabetic rats modulates airway surface liquid glucose concentration and bacterial proliferation.

    PubMed

    Oliveira, Tales Lyra; Candeia-Medeiros, Návylla; Cavalcante-Araújo, Polliane M; Melo, Igor Santana; Fávaro-Pípi, Elaine; Fátima, Luciana Alves; Rocha, Antônio Augusto; Goulart, Luiz Ricardo; Machado, Ubiratan Fabres; Campos, Ruy R; Sabino-Silva, Robinson

    2016-01-01

    High glucose concentration in the airway surface liquid (ASL) is an important feature of diabetes that predisposes to respiratory infections. We investigated the role of alveolar epithelial SGLT1 activity on ASL glucose concentration and bacterial proliferation. Non-diabetic and diabetic rats were intranasally treated with saline, isoproterenol (to increase SGLT1 activity) or phlorizin (to decrease SGLT1 activity); 2 hours later, glucose concentration and bacterial proliferation (methicillin-resistant Sthaphylococcus aureus, MRSA and Pseudomonas aeruginosa, P. aeruginosa) were analyzed in bronchoalveolar lavage (BAL); and alveolar SGLT1 was analyzed by immunohistochemistry. BAL glucose concentration and bacterial proliferation increased in diabetic animals: isoproterenol stimulated SGLT1 migration to luminal membrane, and reduced (50%) the BAL glucose concentration; whereas phlorizin increased the BAL glucose concentration (100%). These regulations were accompanied by parallel changes of in vitro MRSA and P. aeruginosa proliferation in BAL (r = 0.9651 and r = 0.9613, respectively, Pearson correlation). The same regulations were observed in in vivo P. aeruginosa proliferation. In summary, the results indicate a relationship among SGLT1 activity, ASL glucose concentration and pulmonary bacterial proliferation. Besides, the study highlights that, in situations of pulmonary infection risk, such as in diabetic subjects, increased SGLT1 activity may prevent bacterial proliferation whereas decreased SGLT1 activity can exacerbate it. PMID:26902517

  6. SGLT1 activity in lung alveolar cells of diabetic rats modulates airway surface liquid glucose concentration and bacterial proliferation

    PubMed Central

    Oliveira, Tales Lyra; Candeia-Medeiros, Návylla; Cavalcante-Araújo, Polliane M.; Melo, Igor Santana; Fávaro-Pípi, Elaine; Fátima, Luciana Alves; Rocha, Antônio Augusto; Goulart, Luiz Ricardo; Machado, Ubiratan Fabres; Campos, Ruy R.; Sabino-Silva, Robinson

    2016-01-01

    High glucose concentration in the airway surface liquid (ASL) is an important feature of diabetes that predisposes to respiratory infections. We investigated the role of alveolar epithelial SGLT1 activity on ASL glucose concentration and bacterial proliferation. Non-diabetic and diabetic rats were intranasally treated with saline, isoproterenol (to increase SGLT1 activity) or phlorizin (to decrease SGLT1 activity); 2 hours later, glucose concentration and bacterial proliferation (methicillin-resistant Sthaphylococcus aureus, MRSA and Pseudomonas aeruginosa, P. aeruginosa) were analyzed in bronchoalveolar lavage (BAL); and alveolar SGLT1 was analyzed by immunohistochemistry. BAL glucose concentration and bacterial proliferation increased in diabetic animals: isoproterenol stimulated SGLT1 migration to luminal membrane, and reduced (50%) the BAL glucose concentration; whereas phlorizin increased the BAL glucose concentration (100%). These regulations were accompanied by parallel changes of in vitro MRSA and P. aeruginosa proliferation in BAL (r = 0.9651 and r = 0.9613, respectively, Pearson correlation). The same regulations were observed in in vivo P. aeruginosa proliferation. In summary, the results indicate a relationship among SGLT1 activity, ASL glucose concentration and pulmonary bacterial proliferation. Besides, the study highlights that, in situations of pulmonary infection risk, such as in diabetic subjects, increased SGLT1 activity may prevent bacterial proliferation whereas decreased SGLT1 activity can exacerbate it. PMID:26902517

  7. Localization of the active site of an enzyme, bacterial luciferase, using two-quantum affinity modification

    NASA Astrophysics Data System (ADS)

    Benimetskaya, L. Z.; Gitelzon, I. I.; Kozionov, Andrew L.; Novozhilov, S. Y.; Petushkov, V. N.; Rodionova, N. S.; Stockman, Mark I.

    1991-11-01

    For the first time the method of two-quantum affinity modification has been employed to probe the structure of an enzyme, bacterial luciferase. Position of the flavin-binding site of this enzyme, which was previously unknown, has been established. The obtained data indicate that the flavin site is positioned on the (alpha) -subunit. The closest contact of the protein chain of the enzyme with the chromophoric group of the flavin takes place near 80 +/- 10 and 120 +/- 10 amino acid residues; the regions 50 +/- 10 and 215 +/- 10 are also close to the flavin. The established localization does not contradict suggestions on positions of the flavin and phosphate sites of the bacterial luciferase, which had earlier been made from the data on evolutionary stability of various luciferases. The present method can, in principle, be applied to a great number of enzymes, including all flavin-dependent enzymes. Enzymatic catalysis has high speed and specificity. Creation of a method of determination of the elements of the primary structure of a protein, making up the active site (in which substratum conversion occurs), could be a significant advance in clearing up mechanisms of enzymatic catalysis. It was proposed to localize active sites of the enzymes, whose substrata are chromophores, using this method of two-quantum affinity modification. An enzyme- substratum complex is irradiated with laser light of sufficiently long wavelength ((lambda) 300 nm) which is not directly absorbed by the enzyme. Two-quantum quasiresonant excitation of the substratum activates it to the state with energy 5-7 eV, which is then radiativelessly transferred to neighboring protein groups. This energy exceeds the energy of activation of peptide bond breakage. Therefore, the enzyme will be disrupted in the vicinity of its active site. In the present paper the above approach has been implemented for the first time. Information has been obtained about the position of the flavin-binding site of bacterial

  8. A slow-release system of bacterial cellulose gel and nanoparticles for hydrophobic active ingredients.

    PubMed

    Numata, Yukari; Mazzarino, Leticia; Borsali, Redouane

    2015-01-01

    A combination of bacterial cellulose (BC) gel and amphiphilic block copolymer nanoparticles was investigated as a drug delivery system (DDS) for hydrophobic active ingredients. Poly(ethylene oxide)-b-poly(caprolactone) (PEO-b-PCL) and retinol were used as the block copolymer and hydrophobic active ingredient, respectively. The BC gel was capable of incorporating copolymer nanoparticles and releasing them in an acetic acid-sodium acetate buffer solution (pH 5.2) at 37 °C. The percentage of released copolymer reached a maximum value of approximately 60% after 6h and remained constant after 24h. The percentage of retinol released from the copolymer-containing BC gel reached a maximum value at 4h. These results show that the combination of BC gel and nanoparticles is a slow-release system that may be useful in the cosmetic and biomedical fields for skin treatment and preparation. PMID:25840273

  9. Effect of long-term industrial waste effluent pollution on soil enzyme activities and bacterial community composition.

    PubMed

    Subrahmanyam, Gangavarapu; Shen, Ju-Pei; Liu, Yu-Rong; Archana, Gattupalli; Zhang, Li-Mei

    2016-02-01

    Although numerous studies have addressed the influence of exogenous pollutants on microorganisms, the effect of long-term industrial waste effluent (IWE) pollution on the activity and diversity of soil bacteria was still unclear. Three soil samples characterized as uncontaminated (R1), moderately contaminated (R2), and highly contaminated (R3) receiving mixed organic and heavy metal pollutants for more than 20 years through IWE were collected along the Mahi River basin, Gujarat, western India. Basal soil respiration and in situ enzyme activities indicated an apparent deleterious effect of IWE on microbial activity and soil function. Community composition profiling of soil bacteria using 16S rRNA gene amplification and denaturing gradient gel electrophoresis (DGGE) method indicated an apparent bacterial community shift in the IWE-affected soils. Cloning and sequencing of DGGE bands revealed that the dominated bacterial phyla in polluted soil were affiliated with Firmicutes, Acidobacteria, and Actinobacteria, indicating that these bacterial phyla may have a high tolerance to pollutants. We suggested that specific bacterial phyla along with soil enzyme activities could be used as relevant biological indicators for long-term pollution assessment on soil quality. Graphical Abstract Bacterial community profiling and soil enzyme activities in long-term industrial waste effluent polluted soils. PMID:26803661

  10. [Effects of different catch modes on soil enzyme activities and bacterial community in the rhizosphere of cucumber].

    PubMed

    Li, Min; Wu, Feng-zhi

    2014-12-01

    Effects of different catch modes on soil enzyme activities and bacterial community in the rhizosphere of cucumber (Cucumis sativus) were analyzed by conventional chemical method, PCR-denaturing gradient gel electrophoresis (DGGE) and real-time PCR methods. Pot experiment was carried out in the greenhouse for three consecutive years with cucumber as the main crop, and scallion (Allium fistulosum), wheat (Triticum aestivum) and oilseed rape (Brassica campestri) as catch crops. Results showed that, with the increase of crop planting times, soil urease, neutral phosphatase and invertase activities in the wheat treatment were significantly) higher than in the scallion and oilseed rape treatments, and these enzyme activities in the oilseed rape treatment were significantly higher than in the scallion treatment. PCR-DGGR analysis showed that cucumber rhizosphere bacterial community structures were different among treatments. Scallion and wheat treatments maintained relatively higher diversity indices of bacterial community structure. qPCR results showed that the abundance of soil bacterial community in the wheat treatment was significantly higher than in the scallion and oilseed rape treatments. In conclusion, different catch treatments affected soil enzyme activities and bacteria community and changed the soil environment. Wheat used as summer catch crop could maintain relatively higher soil enzyme activities, bacterial community diversity and abundance. PMID:25876408

  11. Pectinolytic systems of two aerobic sporogenous bacterial strains with high activity on pectin.

    PubMed

    Soriano, Margarita; Diaz, Pilar; Pastor, F I Javier

    2005-02-01

    Strains Paenibacillus sp. BP-23 and Bacillus sp. BP-7, previously isolated from soil from a rice field, secreted high levels of pectinase activity in media supplemented with pectin. Production of pectinases in strain Paenibacillus sp. BP-23 showed catabolite repression, while in Bacillus sp. BP-7 production of pectin degrading enzymes was not negatively affected by glucose. The two strains showed lyase activities as the predominant pectinases, while hydrolase activity was very low. Analysis of Paenibacillus sp. BP-23 in SDS-polyacrylamide gels and zymograms showed five pectinase activity bands. The strict requirement of Ca(2+) for lyase activity of the strain indicates that correspond to pectate lyases. For Bacillus sp. BP-7, zymograms showed four bands of different size. The strain showed a Ca(2+) requirement for lyase activity on pectate but not on pectin, indicating that the pectinolytic system of Bacillus sp. BP-7 is comprised of pectate lyases and pectin lyases. The results show differences in pectin degrading systems between the two aerobic sporogenous bacterial strains studied. PMID:15717229

  12. Variability in In Vitro Macrophage Activation by Commercially Diverse Bulk Echinacea Plant Material is Predominantly Due to Bacterial Lipoproteins and Lipopolysaccharides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We previously reported that the majority of in vitro monocyte/macrophage activation exhibited by extracts of Echinacea and other botanicals depends upon bacterial lipopolysaccharides and Braun-type bacterial lipoproteins. We determined the contribution made by these bacterial components to the overa...

  13. A 17-mer Membrane-Active MSI-78 Derivative with Improved Selectivity toward Bacterial Cells.

    PubMed

    Monteiro, Claudia; Pinheiro, Marina; Fernandes, Mariana; Maia, Sílvia; Seabra, Catarina L; Ferreira-da-Silva, Frederico; Reis, Salette; Gomes, Paula; Martins, M Cristina L

    2015-08-01

    Antimicrobial peptides are widely recognized as an excellent alternative to conventional antibiotics. MSI-78, a highly effective and broad spectrum AMP, is one of the most promising AMPs for clinical application. In this study, we have designed shorter derivatives of MSI-78 with the aim of improving selectivity while maintaining antimicrobial activity. Shorter 17-mer derivatives were created by truncating MSI-78 at the N- and/or C-termini, while spanning MSI-78 sequence. Despite the truncations made, we found a 17-mer peptide, MSI-78(4-20) (KFLKKAKKFGKAFVKIL), which was demonstrated to be as effective as MSI-78 against the Gram-positive Staphylococcus strains tested and the Gram-negative Pseudomonas aeruginosa. This shorter derivative is more selective toward bacterial cells as it was less toxic to erythrocytes than MSI-78, representing an improved version of the lead peptide. Biophysical studies support a mechanism of action for MSI-78(4-20) based on the disruption of the bacterial membrane permeability barrier, which in turn leads to loss of membrane integrity and ultimately to cell death. These features point to a mechanism of action similar to the one described for the lead peptide MSI-78. PMID:26066462

  14. Algal and Bacterial Activities in Acidic (pH 3) Strip Mine Lakes

    PubMed Central

    Gyure, Ruth A.; Konopka, Allan; Brooks, Austin; Doemel, William

    1987-01-01

    Reservoir 29 and Lake B are extremely acid lakes (epilimnion pHs of 2.7 and 3.2, respectively), because they receive acidic discharges from coal refuse piles. They differ in that the pH of profundal sediments in Reservoir 29 increased from 2.7 to 3.8 during the period of thermal stratification, whereas permanently anoxic sediments in Lake B had a pH of 6.2. The pH rise in Reservoir 29 sediments was correlated with a temporal increase in H2S concentration in the anaerobic hypolimnion from 0 to >1 mM. The chlorophyll a levels in the epilimnion of Reservoir 29 were low, and the rate of primary production was typical of an oligotrophic system. However, there was a dense 10-cm layer of algal biomass at the bottom of the metalimnion. Production by this layer was low owing to light limitation and possibly H2S toxicity. The specific photosynthetic rates of epilimnetic algae were low, which suggests that nutrient availability is more important than pH in limiting production. The highest photosynthetic rates were obtained in water samples incubated at pH 2.7 to 4. Heterotrophic bacterial activity (measured by [14C]glucose metabolism) was greatest at the sediment/water interface. Bacterial production (assayed by thymidine incorporation) was as high in Reservoir 29 as in a nonacid mesotrophic Indiana lake. PMID:16347430

  15. Nε−Lysine Acetylation of a Bacterial Transcription Factor Inhibits Its DNA-Binding Activity

    PubMed Central

    Thao, Sandy; Chen, Chien-Sheng; Zhu, Heng; Escalante-Semerena, Jorge C.

    2010-01-01

    Evidence suggesting that eukaryotes and archaea use reversible Nε-lysine (Nε-Lys) acetylation to modulate gene expression has been reported, but evidence for bacterial use of Nε-Lys acetylation for this purpose is lacking. Here, we report data in support of the notion that bacteria can control gene expression by modulating the acetylation state of transcription factors (TFs). We screened the E. coli proteome for substrates of the bacterial Gcn5-like protein acetyltransferase (Pat). Pat acetylated four TFs, including the RcsB global regulatory protein, which controls cell division, and capsule and flagellum biosynthesis in many bacteria. Pat acetylated residue Lys180 of RcsB, and the NAD+-dependent Sir2 (sirtuin)-like protein deacetylase (CobB) deacetylated acetylated RcsB (RcsBAc), demonstrating that Nε-Lys acetylation of RcsB is reversible. Analysis of RcsBAc and variant RcsB proteins carrying substitutions at Lys180 provided biochemical and physiological evidence implicating Lys180 as a critical residue for RcsB DNA-binding activity. These findings further the likelihood that reversible Nε-Lys acetylation of transcription factors is a mode of regulation of gene expression used by all cells. PMID:21217812

  16. Particle-associated extracellular enzyme activity and bacterial community composition across the Canadian Arctic Ocean.

    PubMed

    Kellogg, Colleen T E; Deming, Jody W

    2014-08-01

    Microbial enzymatic hydrolysis of marine-derived particulate organic carbon (POC) can be a dominant mechanism for attenuating carbon flux in cold Arctic waters during spring and summer. Whether this mechanism depends on composition of associated microbial communities and extends into other seasons is not known. Bacterial community composition (BCC) and extracellular enzyme activity (EEA, for leucine aminopeptidases, glucosidases and chitobiases) were measured on small suspended particles and potentially sinking aggregates collected during fall from waters of the biologically productive North Water and river-impacted Beaufort Sea. Although other environmental variables appeared influential, both BCC and EEA varied along a marine productivity gradient in the two regions. Aggregates harbored the most distinctive bacterial communities, with a small number of taxa driving differences between particle-size classes (1.0-60 and > 60 μm) and free-living bacteria (0.2-1.0 μm). Significant relationships between patterns in particle-associated BCC and EEA suggest strong links between these two variables. Calculations indicated that up to 80% of POC in the euphotic zone of the North Water, and 20% in the Beaufort Sea, may be hydrolyzed enzymatically, underscoring the importance of this mechanism in attenuating carbon fluxes in Arctic waters even as winter approaches. PMID:24666253

  17. The Metabolically Active Bacterial Microbiome of Tonsils and Mandibular Lymph Nodes of Slaughter Pigs

    PubMed Central

    Mann, Evelyne; Pinior, Beate; Wetzels, Stefanie U.; Metzler-Zebeli, Barbara U.; Wagner, Martin; Schmitz-Esser, Stephan

    2015-01-01

    The exploration of microbiomes in lymphatic organs is relevant for basic and applied research into explaining microbial translocation processes and understanding cross-contamination during slaughter. This study aimed to investigate whether metabolically active bacteria (MAB) could be detected within tonsils and mandibular lymph nodes (MLNs) of pigs. The hypervariable V1-V2 region of the bacterial 16S rRNA genes was amplified from cDNA from tonsils and MLNs of eight clinically healthy slaughter pigs. Pyrosequencing yielded 82,857 quality-controlled sequences, clustering into 576 operational taxonomic units (OTUs), which were assigned to 230 genera and 16 phyla. The actual number of detected OTUs per sample varied highly (23–171 OTUs). Prevotella zoogleoformans and Serratia proteamaculans (best type strain hits) were most abundant (10.6 and 41.8%, respectively) in tonsils and MLNs, respectively. To explore bacterial correlation patterns between samples of each tissue, pairwise Spearman correlations (rs) were calculated. In total, 194 strong positive and negative correlations |rs| ≥ 0.6 were found. We conclude that (i) lymphatic organs harbor a high diversity of MAB, (ii) the occurrence of viable bacteria in lymph nodes is not restricted to pathological processes and (iii) lymphatic tissues may serve as a contamination source in pig slaughterhouses. This study confirms the necessity of the EFSA regulation with regard to a meat inspection based on visual examinations to foster a minimization of microbial contamination. PMID:26696976

  18. Pretreatment with alum or powdered activated carbon reduces bacterial predation-associated irreversible fouling of membranes.

    PubMed

    Kim, Eun-Ho; Dwidar, Mohammed; Kwon, Young-Nam; Mitchell, Robert J

    2014-01-01

    This study evaluated the co-application of bacterial predation by Bdellovibrio bacteriovorus and either alum coagulation or powdered activated carbon adsorption to reduce fouling caused by Escherichia coli rich feed solutions in dead-end microfiltration tests. The flux increased when the samples were predated upon or treated with 100 ppm alum or PAC, but co-treatment with alum and predation gave the best flux results. The total membrane resistance caused by the predated sample was reduced six-fold when treated with 100 ppm PAC, from 11.8 to 1.98 × 10(11) m(-1), while irreversible fouling (Rp) was 2.7-fold lower. Treatment with 100 ppm alum reduced the total resistance 14.9-fold (11.8 to 0.79 × 10(11) m(-1)) while the Rp decreased 4.25-fold. SEM imaging confirmed this, with less obvious fouling of the membrane after the combined process. This study illustrates that the combination of bacterial predation and the subsequent removal of debris using coagulation or adsorption mitigates membrane biofouling and improves membrane performance. PMID:25410737

  19. Perturbation of bacterial ice nucleation activity by a grass antifreeze protein.

    PubMed

    Tomalty, Heather E; Walker, Virginia K

    2014-09-26

    Certain plant-associating bacteria produce ice nucleation proteins (INPs) which allow the crystallization of water at high subzero temperatures. Many of these microbes are considered plant pathogens since the formed ice can damage tissues, allowing access to nutrients. Intriguingly, certain plants that host these bacteria synthesize antifreeze proteins (AFPs). Once freezing has occurred, plant AFPs likely function to inhibit the growth of large damaging ice crystals. However, we postulated that such AFPs might also serve as defensive mechanisms against bacterial-mediated ice nucleation. Recombinant AFP derived from the perennial ryegrass Lolium perenne (LpAFP) was combined with INP preparations originating from the grass epiphyte, Pseudomonas syringae. The presence of INPs had no effect on AFP activity, including thermal hysteresis and ice recrystallization inhibition. Strikingly, the ice nucleation point of the INP was depressed up to 1.9°C in the presence of LpAFP, but a recombinant fish AFP did not lower the INP-imposed freezing point. Assays with mutant LpAFPs and the visualization of bacterially-displayed fluorescent plant AFP suggest that INP and LpAFP can interact. Thus, we postulate that in addition to controlling ice growth, plant AFPs may also function as a defensive strategy against the damaging effects of ice-nucleating bacteria. PMID:25193694

  20. Community dynamics and glycoside hydrolase activities of thermophilic bacterial consortia adapted to switchgrass

    SciTech Connect

    Gladden, J.M.; Allgaier, M.; Miller, C.S.; Hazen, T.C.; VanderGheynst, J.S.; Hugenholtz, P.; Simmons, B.A.; Singer, S.W.

    2011-05-01

    Industrial-scale biofuel production requires robust enzymatic cocktails to produce fermentable sugars from lignocellulosic biomass. Thermophilic bacterial consortia are a potential source of cellulases and hemicellulases adapted to harsher reaction conditions than commercial fungal enzymes. Compost-derived microbial consortia were adapted to switchgrass at 60 C to develop thermophilic biomass-degrading consortia for detailed studies. Microbial community analysis using small-subunit rRNA gene amplicon pyrosequencing and short-read metagenomic sequencing demonstrated that thermophilic adaptation to switchgrass resulted in low-diversity bacterial consortia with a high abundance of bacteria related to thermophilic paenibacilli, Rhodothermus marinus, and Thermus thermophilus. At lower abundance, thermophilic Chloroflexi and an uncultivated lineage of the Gemmatimonadetes phylum were observed. Supernatants isolated from these consortia had high levels of xylanase and endoglucanase activities. Compared to commercial enzyme preparations, the endoglucanase enzymes had a higher thermotolerance and were more stable in the presence of 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), an ionic liquid used for biomass pretreatment. The supernatants were used to saccharify [C2mim][OAc]-pretreated switchgrass at elevated temperatures (up to 80 C), demonstrating that these consortia are an excellent source of enzymes for the development of enzymatic cocktails tailored to more extreme reaction conditions.

  1. Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity

    NASA Astrophysics Data System (ADS)

    Aramwit, Pornanong; Bang, Nipaporn; Ratanavaraporn, Juthamas; Ekgasit, Sanong

    2014-02-01

    In this study, a `green chemistry' approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO- and NH2 + groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.

  2. Rates of dissolved organic carbon (DOC) production and bacterial activity in the eastern North Atlantic Subtropical Gyre during summer

    NASA Astrophysics Data System (ADS)

    Teira, E.; Pazó, M. J.; Quevedo, M.; Fuentes, M. V.; Niell, F. X.; Fernández, E.

    2003-04-01

    Rates of particulate organic carbon production, dissolved organic carbon production (DOC) and bacterial production were measured at 8 stations located in the eastern North Atlantic Subtropical Gyre during August 1998. Euphotic-depth-integrated particulate organic carbon (POC) production rate was on average 27 mg C m-2 h-1. The corresponding averaged integrated DOC production rate was 5 mg C m-2 h-1, i.e., about 20 % of total primary production. No statistically significant relationship was found between the rates of DOC and POC production, suggesting that other processes besides phytoplankton exudation, such as cell lysis or protist grazing, could substantially contribute to the release of DOC. Euphotic-depth-integrated bacterial biomass and production were, on average, 214 mg C m-2 and 1.4 mg C m-2 h-1, respectively. The lack of correlation between the rates of DOC release and bacterial activity, and a bacterial carbon demand (BCD, calculated by using an estimated bacterial growth efficiency ranging from 11 to 18%) in excess of DOC production suggest the existence of additional organic carbon sources (both allochthonous and/or autochthonous reservoirs), apart from in situ phytoplankton-derived DOC production, for the maintenance of bacterial activity in this region during summer.

  3. Mantle compensation of active metamorphic core complexes at Woodlark rift in Papua New Guinea.

    PubMed

    Abers, Geoffrey A; Ferris, Aaron; Craig, Mitchell; Davies, Hugh; Lerner-Lam, Arthur L; Mutter, John C; Taylor, Brian

    2002-08-22

    In many highly extended rifts on the Earth, tectonic removal of the upper crust exhumes mid-crustal rocks, producing metamorphic core complexes. These structures allow the upper continental crust to accommodate tens of kilometres of extension, but it is not clear how the lower crust and underlying mantle respond. Also, despite removal of the upper crust, such core complexes remain both topographically high and in isostatic equilibrium. Because many core complexes in the western United States are underlain by a flat Moho discontinuity, it has been widely assumed that their elevation is supported by flow in the lower crust or by magmatic underplating. These processes should decouple upper-crust extension from that in the mantle. In contrast, here we present seismic observations of metamorphic core complexes of the western Woodlark rift that show the overall crust to be thinned beneath regions of greatest surface extension. These core complexes are actively being exhumed at a rate of 5-10 km Myr(-1), and the thinning of the underlying crust appears to be compensated by mantle rocks of anomalously low density, as indicated by low seismic velocities. We conclude that, at least in this case, the development of metamorphic core complexes and the accommodation of high extension is not purely a crustal phenomenon, but must involve mantle extension. PMID:12192406

  4. A Bacterial Hemerythrin Domain Regulates Activity of a Vibrio cholerae Di-Guanylate Cyclase

    PubMed Central

    Schaller, Ruth A.; Ali, Syed Khalid; Klose, Karl E.; Kurtz, Donald M.

    2012-01-01

    The first demonstrated example of a regulatory function for a bacterial hemerythrin (Bhr) domain is reported. Bhrs have a characteristic sequence motif providing ligand residues for a type of non-heme diiron site that is known to bind O2 and undergo autoxidation. The amino acid sequence encoded by the gene, VC1216, from Vibrio cholerae O1 biovar El Tor str. N16961 contains an N-terminal Bhr domain connected to a C-terminal domain characteristic of bacterial di-guanylate cyclases (DGCs) that catalyze formation of cyclic di-(3′,5′)-guanosine monophosphate (c-di-GMP) from GTP. This protein, Vc Bhr-DGC, was found to contain two tightly bound non-heme iron atoms per protein monomer. The as-isolated protein showed the spectroscopic signatures of oxo/dicarboxylato-bridged non-heme diferric sites of previously characterized Bhr domains. The diiron site was capable of cycling between diferric and diferrous forms, the latter of which was stable only under anaerobic conditions, undergoing rapid autoxidation upon exposure to air. Vc Bhr-DGC showed approximately 10-times higher DGC activity in the diferrous relative to the diferric form. The level of intracellular c-di-GMP is known to regulate biofilm formation in Vibrio cholerae. The higher DGC activity of the diferrous Vc Bhr-DGC is consistent with induction of biofilm formation in low dioxygen environments. The non-heme diiron cofactor in the Bhr domain thus represents an alternative to heme or flavin for redox and/or diatomic gas sensing and regulation of DGC activity. PMID:23057727

  5. DETECTION OF BACTERIAL CYTOTOXIC ACTIVITIES FROM WATER-DAMAGED CEILING TILE MATERIAL FOLLOWING INCUBATION ON BLOOD AGAR

    EPA Science Inventory

    Samples of ceiling tiles with high levels of bacteria exhibited cytotoxic activities on a HEP-2 tissue culture assay. Ceiling tiles containing low levels of bacterial colonization did not show cytotoxic activities on the HEP-2 tissue culture assay. Using a spread plate procedure ...

  6. Mechanisms of the sialidase and trans-sialidase activities of bacterial sialyltransferases from glycosyltransferase family 80.

    PubMed

    Mehr, Kevin; Withers, Stephen G

    2016-04-01

    Many important biological functions are mediated by complex glycan structures containing the nine-carbon sugar sialic acid (Sia) at terminal, non-reducing positions. Sia are introduced onto glycan structures by enzymes known as sialyltransferases (STs). Bacterial STs from the glycosyltransferase family GT80 are a group of well-studied enzymes used for the synthesis of sialylated glycan structures. While highly efficient at sialyl transfer, these enzymes also demonstrate sialidase and trans-sialidase activities for which there is some debate surrounding the corresponding enzymatic mechanisms. Here we propose a mechanism for STs from the glycosyltransferase family GT80 in which sialidase and trans-sialidase activities occur through reverse sialylation of CMP. The resulting CMP-Sia is then enzymatically hydrolyzed or used as a donor in subsequent ST reactions resulting in sialidase and trans-sialidase activities, respectively. We provide evidence for this mechanism by demonstrating that CMP is required for sialidase and trans-sialidase activities and that its removal with phosphatase ablates activity. We also confirm the formation of CMP-Sia using a coupled enzyme assay. A clear understanding of the sialidase and trans-sialidase mechanisms for this class of enzymes allows for more effective use of these enzymes in the synthesis of glycoconjugates. PMID:26582604

  7. Influence of zinc on bacterial populations and their proteolytic enzyme activities in freshwater environments: a cross-site comparison.

    PubMed

    Rasmussen, Lauren; Olapade, Ola A

    2016-04-01

    Temporal responses of indigenous bacterial populations and proteolytic enzyme (i.e., aminopeptidase) activities in the bacterioplankton assemblages from 3 separate freshwater environments were examined after exposure to various zinc (Zn) concentrations under controlled microcosm conditions. Zn concentrations (ranging from 0 to 10 μmol/L) were added to water samples collected from the Kalamazoo River, Rice Creek, and Huron River and examined for bacterial abundance and aminopeptidase activities at various time intervals over a 48 h incubation period in the dark. The results showed that the Zn concentrations did not significantly influence total bacterial counts directly; however, aminopeptidase activities varied significantly to increasing zinc treatments over time. Also, analysis of variance and linear regression analyses revealed significant positive relationships between bacterial numbers and their hydrolytic enzyme activities, suggesting that both probably co-vary with increasing Zn concentrations in aquatic systems. The results from this study serve as additional evidence of the ecological role of Zn as an extracellular peptidase cofactor on the dynamics of bacterial assemblages in aquatic environments. PMID:26877164

  8. PeV Neutrinos Observed by IceCube from Cores of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.

    2013-01-01

    I show that the high energy neutrino flux predicted to arise from active galactic nuclei cores can explain the PeV neutrinos detected by IceCube without conflicting with the constraints from the observed extragalactic cosmic-ray and gamma-ray backgrounds.

  9. Core-shell structured TiO2@polydopamine for highly active visible-light photocatalysis.

    PubMed

    Mao, Wen-Xin; Lin, Xi-Jie; Zhang, Wei; Chi, Zi-Xiang; Lyu, Rong-Wen; Cao, An-Min; Wan, Li-Jun

    2016-06-01

    This communication reports that the TiO2@polydopamine nanocomposite with a core-shell structure could be a highly active photocatalyst working under visible light. A very thin layer of polydopamine at around 1 nm was found to be critical for the degradation of Rhodamine B. PMID:27165843

  10. Effect of optical pumping on the refractive index and temperature in the core of active fibre

    SciTech Connect

    Gainov, V V; Ryabushkin, Oleg A

    2011-09-30

    This paper examines the refractive index change (RIC) induced in the core of Yb{sup 3+}-doped active silica fibres by pulsed pumping. RIC kinetic measurements with a Mach - Zehnder interferometer make it possible to separately assess the contributions of the electronic and thermal mechanisms to the RIC and evaluate temperature nonuniformities in the fibre.

  11. Novel Cu@SiO2/bacterial cellulose nanofibers: Preparation and excellent performance in antibacterial activity.

    PubMed

    Ma, Bo; Huang, Yang; Zhu, Chunlin; Chen, Chuntao; Chen, Xiao; Fan, Mengmeng; Sun, Dongping

    2016-05-01

    The antibacterial composite based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of SiO2 coated Cu nanoparticles (Cu@SiO2/BC) and its properties were characterized. Its chemical structures and morphologies were evaluated by Fourier transformation infrared spectrum (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the SiO2 coated Cu particles were well homogeneously precipitated on the surface of BC. The Cu@SiO2/BC was more resistant to oxidation than the Cu nanoparticles impregnated into BC (Cu/BC) and then Cu@SiO2/BC could prolong the antimicrobial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). PMID:26952469

  12. Effect of Bacterial Cell Moisture on the Sporicidal Activity of β-Propiolactone Vapor

    PubMed Central

    Hoffman, Robert K.

    1968-01-01

    The activity of a vapor-phase disinfectant is usually expressed in terms of the atmospheric relative humidity (RH). This study shows that, in β-propiolactone (BPL) vapor disinfection, the important factor is really the moisture content and location of water in the cell, and not necessarily the atmospheric RH. Previous studies revealed that only about 50% of the bacterial spores equilibrated to 45% RH were killed when exposed to the same RH to BPL vapor. On the other hand, all the spores equilibrated to and then exposed at 75% RH to BPL were readily killed. The present study shows that spores equilibrated to 98% RH are readily killed by BPL at 45% RH, but only 99% of the spores equilibrated to 75% RH are killed by BPL at 45% RH. Also, in order to be killed, desiccated spores must be exposed to BPL at higher humidities than would be required if the spores had not been previously desiccated. PMID:4967453

  13. Improvement of antimicrobial activity of graphene oxide/bacterial cellulose nanocomposites through the electrostatic modification.

    PubMed

    Yang, Xiao-Ning; Xue, Dong-Dong; Li, Jia-Ying; Liu, Miao; Jia, Shi-Ru; Chu, Li-Qiang; Wahid, Fazli; Zhang, Yu-Ming; Zhong, Cheng

    2016-01-20

    Graphene oxide (GO) has an attracting and ever-growing interest in various research fields for its fascinating nanostructures. In this study, bacterial cellulose (BC) was used as a matrix to synthesize GO-based materials by a mechanical mixing method. The modification of GO with PEI significantly improved the bonding force between GO nanofillers and BC matrix. The morphology of the nanocomposites had a significant effect on the mechanical properties, hydrophilic properties as well as the antibacterial activity. After the modification, the GO-PEI/BC showed a strong antimicrobial effect on Saccharomyces cerevisiae due to the effective direct contacts between the nanofillers of the composites and the cell surfaces. This study demonstrates that the morphology of the nanocomposites has a great effect on physiochemical properties and the interactions between the microorganism and the nanocomposites. PMID:26572458

  14. Activation of bacterial channel MscL in mechanically stimulated droplet interface bilayers

    PubMed Central

    Najem, Joseph S.; Dunlap, Myles D.; Rowe, Ian D.; Freeman, Eric C.; Grant, John W.; Sukharev, Sergei; Leo, Donald J.

    2015-01-01

    MscL, a stretch-activated channel, saves bacteria experiencing hypo-osmotic shocks from lysis. Its high conductance and controllable activation makes it a strong candidate to serve as a transducer in stimuli-responsive biomolecular materials. Droplet interface bilayers (DIBs), flexible insulating scaffolds for such materials, can be used as a new platform for incorporation and activation of MscL. Here, we report the first reconstitution and activation of the low-threshold V23T mutant of MscL in a DIB as a response to axial compressions of the droplets. Gating occurs near maximum compression of both droplets where tension in the membrane is maximal. The observed 0.1–3 nS conductance levels correspond to the V23T-MscL sub-conductive and fully open states recorded in native bacterial membranes or liposomes. Geometrical analysis of droplets during compression indicates that both contact angle and total area of the water-oil interfaces contribute to the generation of tension in the bilayer. The measured expansion of the interfaces by 2.5% is predicted to generate a 4–6 mN/m tension in the bilayer, just sufficient for gating. This work clarifies the principles of interconversion between bulk and surface forces in the DIB, facilitates the measurements of fundamental membrane properties, and improves our understanding of MscL response to membrane tension. PMID:26348441

  15. Bacterial production, glucosidase activity and particle-associated carbohydrates in Dona Paula bay, west coast of India

    NASA Astrophysics Data System (ADS)

    Bhaskar, P. V.; Bhosle, N. B.

    2008-11-01

    Size-fractionated bacterial production, abundance and α- and β- glucosidase enzyme activities were studied with respect to changes in hydrography, total suspended matter (TSM), chlorophyll a, particulate organic carbon and nitrogen ratio (POC:PON), 1.5 M NaCl-soluble and 10 mM EDTA-soluble carbohydrates (Sal-PCHO and CPCHO) and transparent exopolymeric particles (TEP) in the surface waters from July 1999-2000 at a shallow coastal station in Dona Paula Bay, west coast of India. The bulk of the total bacterial production and glucosidase activity were associated with particles (75% and >80%, respectively). Total bacterial production was linearly correlated to chlorophyll a ( r = 0.513; p < 0.05) whereas enzyme activity was significantly correlated to TSM (α-glucosidase: r = 0.721 ( p < 0.001); β-glucosidase: r = 0.596 ( p < 0.01)). Both α-glucosidase ( r = 0.514; p < 0.05) and β-glucosidase enzymes ( r = 0.598; p < 0.01) appeared to be involved in the degradation of CPCHO and Sal-PCHO, respectively. Changes in α-glucosidase/β-glucosidase ratios highlighted the varying composition of particulate organic matter. The bacterial uptake of 14C-labeled bacterial extracellular carbohydrate measured over 11 days showed a strong linear correlation between 14C-uptake and bacterial production using tritiated thymidine. The turnover rate of 14C-labeled carbohydrate-C was 0.52 d -1, higher than the estimated annual mean potential carbohydrate carbon turnover rate of 0.33 ± 0.2 d -1. Our study suggests that carbohydrates derived from sediments may serve as an important alternative carbon source sustaining the bacterial carbon demand in the surface waters of Dona Paula Bay.

  16. Structure-Activity Relationship of Amino Acid Tunable Lipidated Norspermidine Conjugates: Disrupting Biofilms with Potent Activity against Bacterial Persisters.

    PubMed

    Konai, Mohini M; Adhikary, Utsarga; Samaddar, Sandip; Ghosh, Chandradhish; Haldar, Jayanta

    2015-12-16

    The emergence of bacterial resistance and biofilm associated infections has created a challenging situation in global health. In this present state of affairs where conventional antibiotics are falling short of being able to provide a solution to these problems, development of novel antibacterial compounds possessing the twin prowess of antibacterial and antibiofilm efficacy is imperative. Herein, we report a library of amino acid tunable lipidated norspermidine conjugates that were prepared by conjugating both amino acids and fatty acids with the amine functionalities of norspermidine through amide bond formation. These lipidated conjugates displayed potent antibacterial activity against various planktonic Gram-positive and Gram-negative bacteria including drug-resistant superbugs such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and β-lactam-resistant Klebsiella pneumoniae. This class of nontoxic and fast-acting antibacterial molecules (capable of killing bacteria within 15 min) did not allow bacteria to develop resistance against them after several passages. Most importantly, an optimized compound in the series was also capable of killing metabolically inactive persisters and stationary phase bacteria. Additionally, this compound was capable of disrupting the preformed biofilms of S. aureus and E. coli. Therefore, this class of antibacterial conjugates have potential in tackling the challenging situation posed by both bacterial resistance as well as drug tolerance due to biofilm formation. PMID:26452096

  17. Improved oxygen reduction activity on the Ih Cu@Pt core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, Zongxian; Geng, Zhixia; Zhang, Yanxing; Wang, Jinlong; Ma, Shuhong

    2011-09-01

    The minimum energy path (MEP) for the dissociation of O 2 on the Ih Cu@Pt12 core-shell nanoparticle. Ih Cu@Pt12 is the most stable among the symmetric Cu@Pt12 core-shell isomers. O 2 prefers to be adsorbed on the Ih Cu@Pt12 with the t-b-t configuration. The Ih Cu@Pt12 has enhanced activity for O 2 dissociation and O diffusion. Ih Cu@Pt12 nanoparticle is a good candidate for being the ORR catalyst.

  18. Transcriptional Activation of the Interleukin-2 Promoter by Hepatitis C Virus Core Protein

    PubMed Central

    Bergqvist, Anders; Rice, Charles M.

    2001-01-01

    Most patients infected with hepatitis C virus (HCV) become chronic carriers. Viruses that efficiently establish persistent infections must have effective ways of evading host defenses. In the case of HCV, little is known about how chronic infections are established or maintained. Besides hepatocytes, several reports suggest that HCV can infect T and B lymphocytes. Since T cells are essential for viral clearance, direct or indirect effects of HCV on T-cell function could influence the outcome of infection. Given that T-cell growth and differentiation require the cytokine interleukin 2 (IL-2), we asked whether HCV might modulate synthesis of IL-2. Portions of the HCV polyprotein were expressed in Jurkat cells under a variety of conditions. We found that the highly conserved HCV core protein, in combination with other stimuli, was able to dramatically activate transcription from the IL-2 promoter. The carboxy-terminal hydrophobic portion of the core protein was required for this activity. Activation was dependent on nuclear factor of activated T cells (NFAT), occurred in cells deficient in the tyrosine kinase p56lck, and could be blocked by addition of cyclosporin A and by depletion of calcium. These results suggest that the HCV core protein can activate transcription of the IL-2 promoter through the NFAT pathway. This novel activity may have consequences for T-cell development and establishment of persistent infections. PMID:11134290

  19. T-cell activation or tolerization: the Yin and Yang of bacterial superantigens.

    PubMed

    Sähr, Aline; Förmer, Sandra; Hildebrand, Dagmar; Heeg, Klaus

    2015-01-01

    Bacterial superantigens (SAg) are exotoxins from pathogens which interact with innate and adaptive immune cells. The paradox that SAgs cause activation and inactivation/anergy of T-cells was soon recognized. The structural and molecular events following SAg binding to antigen presenting cells (APCs) followed by crosslinking of T-cell receptors were characterized in detail. Activation, cytokine burst and T-cell anergy have been described in vitro and in vivo. Later it became clear that SAg-induced T-cell anergy is in part caused by SAg-dependent activation of T-regulatory cells (Tregs). Although the main focus of analyses was laid on T-cells, it was also shown that SAg binding to MHC class II molecules on APCs induces a signal, which leads to activation and secretion of pro-inflammatory cytokines. Accordingly APCs are mandatory for T-cell activation. So far it is not known, whether APCs play a role during SAg-triggered activation of Tregs. We therefore tested whether in SAg (Streptococcal pyrogenic exotoxin A) -treated APCs an anti-inflammatory program is triggered in addition. We show here that not only the anti-inflammatory cytokine IL-10 and the co-inhibitory surface molecule PD-L1 (CD274) but also inhibitory effector systems like indoleamine 2,3-dioxygenase (IDO) or intracellular negative feedback loops (suppressor of cytokine signaling molecules, SOCS) are induced by SAgs. Moreover, cyclosporine A completely prevented induction of this program. We therefore propose that APCs triggered by SAgs play a key role in T-cell activation as well as inactivation and induction of Treg cells. PMID:26539181

  20. Pattern reactivation co-varies with activity in the core recollection network during source memory.

    PubMed

    Leiker, Emily K; Johnson, Jeffrey D

    2015-08-01

    Neuroimaging studies of episodic memory have consistently demonstrated that memory retrieval involves reactivating patterns of neural activity that were present during encoding, and these effects are thought to reflect the qualitative retrieval (recollection) of information that is specific to the content of an episode. By contrast, recollection is also accompanied by other neural correlates that generalize across episodic content and are consequently referred to as the "core recollection network". The neural mechanism by which these specific and core effects interact to give rise to episodic memory retrieval is largely unknown. The current study addressed this issue by testing for correlations (connectivity) between pattern reactivation and activity in the core recollection network. Subjects encoded a series of words with different tasks and then completed a two-step source memory test, whereby they identified the task (source) previously associated with the word and the confidence of that judgment. Multivariate pattern analysis (MVPA) was used in combination with fMRI to first identify encoding-related neural patterns and then test for their reactivation during retrieval. Consistent with prior findings, the magnitude of reactivation increased with source-memory confidence. Moreover, individual-trial measures of reactivation exhibited positive correlations with activity in multiple regions of the core recollection network. Importantly, evidence of functional connectivity between pattern reactivation and a region of left posterior parietal cortex supports the role of this region in tracking the retrieval of episodic information in service of making subjective memory decisions. PMID:26004057

  1. Cultivation of a bacterial consortium with the potential to degrade total petroleum hydrocarbon using waste activated sludge.

    PubMed

    Sivakumar, S; Song, Y C; Kim, S H; Jang, S H

    2015-11-01

    Waste activated sludge was aerobically treated to demonstrate multiple uses such as cultivating an oil degrading bacterial consortium; studying the influence of a bulking agent (peat moss) and total petroleum hydrocarbon concentration on bacterial growth and producing a soil conditioner using waste activated sludge. After 30 days of incubation, the concentration of oil-degrading bacteria was 4.3 x 10(8) CFU g(-1) and 4.5 x 10(8) CFU g(-1) for 5 and 10 g of total petroleum hydrocarbon, respectively, in a mixture of waste activated sludge (1 kg) and peat moss (0.1 kg). This accounts for approximately 88.4 and 91.1%, respectively, of the total heterotrophic bacteria (total-HB). The addition of bulking agent enhanced total-HB population and total petroleum hydrocarbon-degrading bacterial population. Over 90% of total petroleum hydrocarbon degradation was achieved by the mixture of waste activated sludge, bulking agent and total petroleum hydrocarbon. The results of physico-chemical parameters of the compost (waste activated sludge with and without added peat moss compost) and a substantial reduction in E. coli showed that the use of this final product did not exhibit risk when used as soil conditioner. Finally, the present study demonstrated that cultivation of total petroleum hydrocarbon-degrading bacterial consortium and production of compost from waste activated sludge by aerobic treatment was feasible. PMID:26688976

  2. Fragmented Lactic Acid Bacterial Cells Activate Peroxisome Proliferator-Activated Receptors and Ameliorate Dyslipidemia in Obese Mice.

    PubMed

    Nakamura, Futoshi; Ishida, Yu; Sawada, Daisuke; Ashida, Nobuhisa; Sugawara, Tomonori; Sakai, Manami; Goto, Tsuyoshi; Kawada, Teruo; Fujiwara, Shigeru

    2016-03-30

    Recent studies suggest that peroxisome proliferator-activated receptor (PPAR) activation ameliorates metabolic disorders, including dyslipidemia. To identify an effective PPAR agonist, we screened the in vitro PPARα/γ activation ability of organic solvent extracts from food-oriented bacterial strains belonging to 5 genera and 32 species, including lactic acid bacteria, and of these, Lactobacillus amylovorus CP1563 demonstrated the highest PPARα/γ agonist activity. We also found that physical fragmentation of the strain could substitute organic solvent extraction for the expression of CP1563 activity in vitro. For functional food manufacturing, we selected the fragmented CP1563 and conducted subsequent animal experiments. In an obese mouse model, we found that treatment with fragmented CP1563 for 12 weeks decreased the levels of low-density lipoprotein (LDL)-cholesterol and triglyceride in plasma, significantly decreased the atherosclerosis index, and increased the plasma high-density lipoprotein (HDL)-cholesterol level. Thus, we conclude that fragmented CP1563 may be a candidate for the prevention and treatment of dyslipidemia. PMID:26927959

  3. Effect of copper on the performance and bacterial communities of activated sludge using Illumina MiSeq platforms.

    PubMed

    Sun, Fu-Lin; Fan, Lei-Lei; Xie, Guang-Jian

    2016-08-01

    The anaerobic-anoxic-aerobic (A2O) process is a highly efficient sewage treatment method, which uses complex bacterial communities. However, the effect of copper on this process and the bacterial communities involved remains unknown. In this study, a systematic investigation of the effect of persistent exposure of copper in the A2O wastewater treatment system was performed. An A2O device was designed to examine the effect of copper on the removal efficiency and microbial community compositions of activated sludge that was continuously treated with 10, 20, and 40 mg L(-1) copper, respectively. Surprisingly, a decrease in chemical oxygen demand (COD) and ammonia nitrogen (NH4N) removal efficiency was observed, and the toxicity of high copper concentration was significantly greater at 7d than at 1d. Proteobacteria, Bacteroidetes, Acidobacteria, Chlorobi, and Nitrospirae were the dominant bacterial taxa in the A2O system, and significant changes in microbial community were observed during the exposure period. Most of the dominant bacterial groups were easily susceptible to copper toxicity and diversely changed at different copper concentrations. However, not all the bacterial taxa were inhibited by copper treatment. At high copper concentration, many bacterial species were stimulated and their abundance increased. Cluster analysis and principal coordinate analysis (PCoA) based on operational taxonomic units (OTUs) revealed clear differences in the bacterial communities among the samples. These findings indicated that copper severely affected the performance and key microbial populations in the A2O system as well as disturbed the stability of the bacterial communities in the system, thus decreasing the removal efficiency. PMID:27179238

  4. Palladium–platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    SciTech Connect

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A.; Mavrikakis, Manos; Xia, Younan

    2015-07-02

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. Ultimately, these results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.

  5. Palladium-platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A.; Mavrikakis, Manos; Xia, Younan

    2015-07-01

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. These results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.

  6. Seasonal Transition of Active Bacterial and Archaeal Communities in Relation to Water Management in Paddy Soils

    PubMed Central

    Itoh, Hideomi; Ishii, Satoshi; Shiratori, Yutaka; Oshima, Kenshiro; Otsuka, Shigeto; Hattori, Masahira; Senoo, Keishi

    2013-01-01

    Paddy soils have an environment in which waterlogging and drainage occur during the rice growing season. Fingerprinting analysis based on soil RNA indicated that active microbial populations changed in response to water management conditions, although the fundamental microbial community was stable as assessed by DNA-based fingerprinting analysis. Comparative clone library analysis based on bacterial and archaeal 16S rRNAs (5,277 and 5,436 clones, respectively) revealed stable and variable members under waterlogged or drained conditions. Clones related to the class Deltaproteobacteria and phylum Euryarchaeota were most frequently obtained from the samples collected under both waterlogged and drained conditions. Clones related to syntrophic hydrogen-producing bacteria, hydrogenotrophic methanogenic archaea, rice cluster III, V, and IV, and uncultured crenarchaeotal group 1.2 appeared in greater proportion in the samples collected under waterlogged conditions than in those collected under drained conditions, while clones belonging to rice cluster VI related to ammonia-oxidizing archaea (AOA) appeared at higher frequency in the samples collected under drained conditions than in those collected under waterlogged conditions. These results suggested that hydrogenotrophic methanogenesis may become active under waterlogged conditions, whereas ammonia oxidation may progress by rice cluster VI becoming active under drained conditions in the paddy field. PMID:24005888

  7. Activation of natural killer cells and cytokine production in man by bacterial extracts.

    PubMed

    Wybran, J; Libin, M; Schandene, L

    1989-01-01

    Broncho-Vaxon (OM-85 BV) is a bacterial extract of eight bacterias usually involved in the respiratory tract infections. Since Broncho-Vaxom is clinically active in decreasing the incidence of such infections, its immunological effect was investigated, in vitro, using peripheral blood mononuclear cells (PBMC). The experimental data indicate that Broncho-Vaxom can modulate various immune functions. It was shown, using a radioimmunoassay for these cytokines, that Broncho-Vaxom will spontaneously enhance TNF alpha and IL-2 production whereas it has no action on IF gamma production. However, when the PBMC are stimulated with PHA, an increased production for IF gamma, TNF alpha and IL-2 was observed suggesting that, under appropriate conditions, Broncho-Vaxom enhances the production of these cytokines. In other experiments, Broncho-Vaxom was shown to markedly increase the natural killer activity of PBMC. All these results demonstrate that Broncho-Vaxom is an immunomodulator affecting multiple immunological mechanisms including the activation of natural killer cells, of monocytes and of T cells through direct mechanisms or through the cytokine cascade. PMID:2503554

  8. Structure and primase-mediated activation of a bacterial dodecameric replicative helicase

    PubMed Central

    Bazin, Alexandre; Cherrier, Mickaël V.; Gutsche, Irina; Timmins, Joanna; Terradot, Laurent

    2015-01-01

    Replicative helicases are essential ATPases that unwind DNA to initiate chromosomal replication. While bacterial replicative DnaB helicases are hexameric, Helicobacter pylori DnaB (HpDnaB) was found to form double hexamers, similar to some archaeal and eukaryotic replicative helicases. Here we present a structural and functional analysis of HpDnaB protein during primosome formation. The crystal structure of the HpDnaB at 6.7 Å resolution reveals a dodecameric organization consisting of two hexamers assembled via their N-terminal rings in a stack-twisted mode. Using fluorescence anisotropy we show that HpDnaB dodecamer interacts with single-stranded DNA in the presence of ATP but has a low DNA unwinding activity. Multi-angle light scattering and small angle X-ray scattering demonstrate that interaction with the DnaG primase helicase-binding domain dissociates the helicase dodecamer into single ringed primosomes. Functional assays on the proteins and associated complexes indicate that these single ringed primosomes are the most active form of the helicase for ATP hydrolysis, DNA binding and unwinding. These findings shed light onto an activation mechanism of HpDnaB by the primase that might be relevant in other bacteria and possibly other organisms exploiting dodecameric helicases for DNA replication. PMID:26264665

  9. Detection of DNA polymerase activities associated with purified duck hepatitis B virus core particles by using an activity gel assay.

    PubMed Central

    Oberhaus, S M; Newbold, J E

    1993-01-01

    Replication of hepadnaviruses involves reverse transcription of an intermediate RNA molecule. It is generally accepted that this replication scheme is carried out by a virally encoded, multifunctional polymerase which has DNA-dependent DNA polymerase, reverse transcriptase, and RNase H activities. Biochemical studies of the polymerase protein(s) have been limited by the inability to purify useful quantities of functional enzyme from virus particles and, until recently, to express enzymatically active polymerase proteins in heterologous systems. An activity gel assay which detects in situ catalytic activities of DNA polymerases after electrophoresis in partially denaturing polyacrylamide gels was used by M.R. Bavand and O. Laub (J. Virol. 62:626-628, 1988) to show the presence of DNA- and RNA-dependent DNA polymerase activities associated with hepatitis B virus particles produced in vitro. This assay has provided the only means by which hepadnavirus polymerase proteins have been detected in association with enzymatic activities. Since conventional methods have not allowed purification of useful quantities of enzymatically active polymerase protein(s), we have devised a protocol for purifying large quantities of duck hepatitis B virus (DHBV) core particles to near homogeneity. These immature virus particles contain DNA- and RNA-dependent DNA polymerase activities, as shown in the endogenous DNA polymerase assay. We have used the activity gel assay to detect multiple DNA- and RNA-dependent DNA polymerase proteins associated with these purified DHBV core particles. These enzymatically active proteins appear larger than, approximately the same size as, and smaller than an unmodified DHBV polymerase protein predicted from the polymerase open reading frame. This is the first report of the detection of active hepadnavirus core-associated DNA polymerase proteins derived from a natural host. Images PMID:8411359

  10. Sesqui- and triterpenoids from the liverwort Lepidozia chordulifera inhibitors of bacterial biofilm and elastase activity of human pathogenic bacteria.

    PubMed

    Gilabert, M; Marcinkevicius, K; Andujar, S; Schiavone, M; Arena, M E; Bardón, A

    2015-01-15

    Five dammarane-type triterpenoids, five pentacyclic triterpenoids (three of them carrying a carboxylic acid group), and two aromadendrane-type sesquiterpenoids were isolated from an Argentinian collection of the liverwort Lepidozia chordulifera. Compounds were characterized by comparison of their spectral data with those previously reported and tested in their ability to control bacterial growth, biofilm formation, bacterial Quorum Sensing process (QS), and elastase activity of Pseudomonas aeruginosa, as well as bacterial growth and biofilm formation of Staphylococcus aureus. The key role played by biofilm and elastase activity in bacterial virulence make them a potential target for the development of antibacterial agents. The aromadendrane-type sesquiterpenoid viridiflorol was the most potent biofilm formation inhibitor, producing 60% inhibition in P. aeruginosa and 40% in S. aureus at 50µg/ml. Ursolic and betulinic acids (two of the pentacyclic triterpenoids isolated) were able to reduce 96 and 92% the elastase activity of P. aeruginosa at 50µg/ml, respectively. Among the analyzed triterpenoids, those that carry a dammarane skeleton were the most potent inhibitors of the P. aeruginosa biofilm formation and were active against both P. aeruginosa and S. aureus. Subsequently, a computer-assisted study of the triterpenoid compounds was carried out for a better understanding of the structure-activity relationships. PMID:25636875

  11. Re-Evaluation of a Bacterial Antifreeze Protein as an Adhesin with Ice-Binding Activity

    PubMed Central

    Guo, Shuaiqi; Garnham, Christopher P.; Whitney, John C.; Graham, Laurie A.; Davies, Peter L.

    2012-01-01

    A novel role for antifreeze proteins (AFPs) may reside in an exceptionally large 1.5-MDa adhesin isolated from an Antarctic Gram-negative bacterium, Marinomonas primoryensis. MpAFP was purified from bacterial lysates by ice adsorption and gel electrophoresis. We have previously reported that two highly repetitive sequences, region II (RII) and region IV (RIV), divide MpAFP into five distinct regions, all of which require mM Ca2+ levels for correct folding. Also, the antifreeze activity is confined to the 322-residue RIV, which forms a Ca2+-bound beta-helix containing thirteen Repeats-In-Toxin (RTX)-like repeats. RII accounts for approximately 90% of the mass of MpAFP and is made up of ∼120 tandem 104-residue repeats. Because these repeats are identical in DNA sequence, their number was estimated here by pulsed-field gel electrophoresis. Structural homology analysis by the Protein Homology/analogY Recognition Engine (Phyre2) server indicates that the 104-residue RII repeat adopts an immunoglobulin beta-sandwich fold that is typical of many secreted adhesion proteins. Additional RTX-like repeats in RV may serve as a non-cleavable signal sequence for the type I secretion pathway. Immunodetection shows both repeated regions are uniformly distributed over the cell surface. We suggest that the development of an AFP-like domain within this adhesin attached to the bacterial outer surface serves to transiently bind the host bacteria to ice. This association would keep the bacteria within the upper reaches of the water column where oxygen and nutrients are potentially more abundant. This novel envirotactic role would give AFPs a third function, after freeze avoidance and freeze tolerance: that of transiently binding an organism to ice. PMID:23144980

  12. Bacterial Ortholog of Mammalian Translocator Protein (TSPO) with Virulence Regulating Activity

    PubMed Central

    Chapalain, Annelise; Chevalier, Sylvie; Orange, Nicole; Murillo, Laurence; Papadopoulos, Vassilios; Feuilloley, Marc G. J.

    2009-01-01

    The translocator protein (TSPO), previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. TSPO is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. Surprisingly, a TSPO-related protein was identified in the photosynthetic bacterium Rhodobacter sphaeroides but it was initially considered as a relict of evolution. In the present study we cloned a tspO gene in Pseudomonas fluorescens MF37, a non-photosynthetic eubacterium and we used bioinformatics tools to identify TSPO in the genome of 97 other bacteria. P. fluorescens TSPO was recognized by antibodies against mouse protein and by PK 11195, an artificial ligand of mitochondrial TSPO. As in eukaryotes, bacterial TSPO appears functionally organized as a dimer and the apparent Kd for PK 11195 is in the same range than for its eukaryotic counterpart. When P. fluorescens MF37 was treated with PK 11195 (10−5 M) adhesion to living or artificial surfaces and biofilm formation activity were increased. Conversely, the apoptotic potential of bacteria on eukaryotic cells was significantly reduced. This effect of PK11195 was abolished in a mutant of P. fluorescens MF37 deficient for its major outer membrane porin, OprF. The present results demonstrate the existence of a bacterial TSPO that shares common structural and functional characteristics with its mammalian counterpart. This protein, apparently involved in adhesion and virulence, reveals the existence of a possible new inter kingdom signalling system and suggests that the human microbiome should be involuntarily exposed to the evolutionary pressure of benzodiazepines and related molecules. This discovery also represents a promising opportunity for the development of alternative antibacterial strategies. PMID:19564920

  13. Bacterial ortholog of mammalian translocator protein (TSPO) with virulence regulating activity.

    PubMed

    Chapalain, Annelise; Chevalier, Sylvie; Orange, Nicole; Murillo, Laurence; Papadopoulos, Vassilios; Feuilloley, Marc G J

    2009-01-01

    The translocator protein (TSPO), previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. TSPO is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. Surprisingly, a TSPO-related protein was identified in the photosynthetic bacterium Rhodobacter sphaeroides but it was initially considered as a relict of evolution. In the present study we cloned a tspO gene in Pseudomonas fluorescens MF37, a non-photosynthetic eubacterium and we used bioinformatics tools to identify TSPO in the genome of 97 other bacteria. P. fluorescens TSPO was recognized by antibodies against mouse protein and by PK 11195, an artificial ligand of mitochondrial TSPO. As in eukaryotes, bacterial TSPO appears functionally organized as a dimer and the apparent Kd for PK 11195 is in the same range than for its eukaryotic counterpart. When P. fluorescens MF37 was treated with PK 11195 (10(-5) M) adhesion to living or artificial surfaces and biofilm formation activity were increased. Conversely, the apoptotic potential of bacteria on eukaryotic cells was significantly reduced. This effect of PK11195 was abolished in a mutant of P. fluorescens MF37 deficient for its major outer membrane porin, OprF. The present results demonstrate the existence of a bacterial TSPO that shares common structural and functional characteristics with its mammalian counterpart. This protein, apparently involved in adhesion and virulence, reveals the existence of a possible new inter kingdom signalling system and suggests that the human microbiome should be involuntarily exposed to the evolutionary pressure of benzodiazepines and related molecules. This discovery also represents a promising opportunity for the development of alternative antibacterial strategies. PMID:19564920

  14. Re-evaluation of a bacterial antifreeze protein as an adhesin with ice-binding activity.

    PubMed

    Guo, Shuaiqi; Garnham, Christopher P; Whitney, John C; Graham, Laurie A; Davies, Peter L

    2012-01-01

    A novel role for antifreeze proteins (AFPs) may reside in an exceptionally large 1.5-MDa adhesin isolated from an Antarctic Gram-negative bacterium, Marinomonas primoryensis. MpAFP was purified from bacterial lysates by ice adsorption and gel electrophoresis. We have previously reported that two highly repetitive sequences, region II (RII) and region IV (RIV), divide MpAFP into five distinct regions, all of which require mM Ca(2+) levels for correct folding. Also, the antifreeze activity is confined to the 322-residue RIV, which forms a Ca(2+)-bound beta-helix containing thirteen Repeats-In-Toxin (RTX)-like repeats. RII accounts for approximately 90% of the mass of MpAFP and is made up of ∼120 tandem 104-residue repeats. Because these repeats are identical in DNA sequence, their number was estimated here by pulsed-field gel electrophoresis. Structural homology analysis by the Protein Homology/analogY Recognition Engine (Phyre2) server indicates that the 104-residue RII repeat adopts an immunoglobulin beta-sandwich fold that is typical of many secreted adhesion proteins. Additional RTX-like repeats in RV may serve as a non-cleavable signal sequence for the type I secretion pathway. Immunodetection shows both repeated regions are uniformly distributed over the cell surface. We suggest that the development of an AFP-like domain within this adhesin attached to the bacterial outer surface serves to transiently bind the host bacteria to ice. This association would keep the bacteria within the upper reaches of the water column where oxygen and nutrients are potentially more abundant. This novel envirotactic role would give AFPs a third function, after freeze avoidance and freeze tolerance: that of transiently binding an organism to ice. PMID:23144980

  15. Increases in Calmodulin Abundance and Stabilization of Activated iNOS Mediate Bacterial Killing in RAW 264.7 Macrophages

    SciTech Connect

    Smallwood, Heather S.; Shi, Liang; Squier, Thomas C.

    2006-08-01

    The rapid activation of macrophages in response to bacterial antigens is central to the innate immune system that permits the recognition and killing of pathogens to limit infection. To understand regulatory mechanisms underlying macrophage activation, we have investigated changes in the abundance of calmodulin (CaM) and iNOS in response to the bacterial cell wall component lipopolysaccharide (LPS) using RAW 264.7 macrophages. Critical to these measurements was the ability to differentiate free iNOS from the CaM-bound (active) form of iNOS associated with nitric oxide generation. We observe a rapid two-fold increase in CaM abundance during the first 30 minutes that is blocked by inhibition of NF?B nuclear translocation or protein synthesis. A similar two-fold increase in the abundance of the complex between CaM and iNOS is observed with the same time dependence. In contrast, there are no detectable increases in the CaM-free (i.e., inactive) form of iNOS within the first hour; it remains at a very low abundance during the initial phase of macrophage activation. Increasing cellular CaM levels in stably transfected cells results in a corresponding increase in the abundance of the CaM/iNOS complex that promotes effective bacterial killing following challenge by Salmonella typhimurium. Thus, LPS-dependent increases in CaM abundance function in the stabilization and activation of iNOS on the rapid time-scale associated with macrophage activation and bacterial killing. These results explain how CaM and iNOS coordinately function to form a stable complex that is part of a rapid host-response that functions within the first 30 minutes following bacterial infection to up-regulate the innate immune system involving macrophage activation.

  16. Ribonucleoprotein particles of bacterial small non-coding RNA IsrA (IS61 or McaS) and its interaction with RNA polymerase core may link transcription to mRNA fate.

    PubMed

    van Nues, Rob W; Castro-Roa, Daniel; Yuzenkova, Yulia; Zenkin, Nikolay

    2016-04-01

    Coupled transcription and translation in bacteria are tightly regulated. Some small RNAs (sRNAs) control aspects of this coupling by modifying ribosome access or inducing degradation of the message. Here, we show that sRNA IsrA (IS61 or McaS) specifically associates with core enzyme of RNAPin vivoandin vitro, independently of σ factor and away from the main nucleic-acids-binding channel of RNAP. We also show that, in the cells, IsrA exists as ribonucleoprotein particles (sRNPs), which involve a defined set of proteins including Hfq, S1, CsrA, ProQ and PNPase. Our findings suggest that IsrA might be directly involved in transcription or can participate in regulation of gene expression by delivering proteins associated with it to target mRNAs through its interactions with transcribing RNAP and through regions of sequence-complementarity with the target. In this eukaryotic-like model only in the context of a complex with its target, IsrA and its associated proteins become active. In this manner, in the form of sRNPs, bacterial sRNAs could regulate a number of targets with various outcomes, depending on the set of associated proteins. PMID:26609136

  17. Ribonucleoprotein particles of bacterial small non-coding RNA IsrA (IS61 or McaS) and its interaction with RNA polymerase core may link transcription to mRNA fate

    PubMed Central

    van Nues, Rob W.; Castro-Roa, Daniel; Yuzenkova, Yulia; Zenkin, Nikolay

    2016-01-01

    Coupled transcription and translation in bacteria are tightly regulated. Some small RNAs (sRNAs) control aspects of this coupling by modifying ribosome access or inducing degradation of the message. Here, we show that sRNA IsrA (IS61 or McaS) specifically associates with core enzyme of RNAP in vivo and in vitro, independently of σ factor and away from the main nucleic-acids-binding channel of RNAP. We also show that, in the cells, IsrA exists as ribonucleoprotein particles (sRNPs), which involve a defined set of proteins including Hfq, S1, CsrA, ProQ and PNPase. Our findings suggest that IsrA might be directly involved in transcription or can participate in regulation of gene expression by delivering proteins associated with it to target mRNAs through its interactions with transcribing RNAP and through regions of sequence-complementarity with the target. In this eukaryotic-like model only in the context of a complex with its target, IsrA and its associated proteins become active. In this manner, in the form of sRNPs, bacterial sRNAs could regulate a number of targets with various outcomes, depending on the set of associated proteins. PMID:26609136

  18. Mass Spectrometric Detection of Bacterial Protein Toxins and Their Enzymatic Activity

    PubMed Central

    Kalb, Suzanne R.; Boyer, Anne E.; Barr, John R.

    2015-01-01

    Mass spectrometry has recently become a powerful technique for bacterial identification. Mass spectrometry approaches generally rely upon introduction of the bacteria into a matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer with mass spectrometric recognition of proteins specific to that organism that form a reliable fingerprint. With some bacteria, such as Bacillus anthracis and Clostridium botulinum, the health threat posed by these organisms is not the organism itself, but rather the protein toxins produced by the organisms. One such example is botulinum neurotoxin (BoNT), a potent neurotoxin produced by C. botulinum. There are seven known serotypes of BoNT, A–G, and many of the serotypes can be further differentiated into toxin variants, which are up to 99.9% identical in some cases. Mass spectrometric proteomic techniques have been established to differentiate the serotype or toxin variant of BoNT produced by varied strains of C. botulinum. Detection of potent biological toxins requires high analytical sensitivity and mass spectrometry based methods have been developed to determine the enzymatic activity of BoNT and the anthrax lethal toxins produced by B. anthracis. This enzymatic activity, unique for each toxin, is assessed with detection of the toxin-induced cleavage of strategically designed peptide substrates by MALDI-TOF mass spectrometry offering unparalleled specificity. Furthermore, activity assays allow for the assessment of the biological activity of a toxin and its potential health risk. Such methods have become important diagnostics for botulism and anthrax. Here, we review mass spectrometry based methods for the enzymatic activity of BoNT and the anthrax lethal factor toxin. PMID:26404376

  19. Mass Spectrometric Detection of Bacterial Protein Toxins and Their Enzymatic Activity.

    PubMed

    Kalb, Suzanne R; Boyer, Anne E; Barr, John R

    2015-09-01

    Mass spectrometry has recently become a powerful technique for bacterial identification. Mass spectrometry approaches generally rely upon introduction of the bacteria into a matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer with mass spectrometric recognition of proteins specific to that organism that form a reliable fingerprint. With some bacteria, such as Bacillus anthracis and Clostridium botulinum, the health threat posed by these organisms is not the organism itself, but rather the protein toxins produced by the organisms. One such example is botulinum neurotoxin (BoNT), a potent neurotoxin produced by C. botulinum. There are seven known serotypes of BoNT, A-G, and many of the serotypes can be further differentiated into toxin variants, which are up to 99.9% identical in some cases. Mass spectrometric proteomic techniques have been established to differentiate the serotype or toxin variant of BoNT produced by varied strains of C. botulinum. Detection of potent biological toxins requires high analytical sensitivity and mass spectrometry based methods have been developed to determine the enzymatic activity of BoNT and the anthrax lethal toxins produced by B. anthracis. This enzymatic activity, unique for each toxin, is assessed with detection of the toxin-induced cleavage of strategically designed peptide substrates by MALDI-TOF mass spectrometry offering unparalleled specificity. Furthermore, activity assays allow for the assessment of the biological activity of a toxin and its potential health risk. Such methods have become important diagnostics for botulism and anthrax. Here, we review mass spectrometry based methods for the enzymatic activity of BoNT and the anthrax lethal factor toxin. PMID:26404376

  20. Antibacterial Activity of Salvadora persica L. (Miswak) Extracts against Multidrug Resistant Bacterial Clinical Isolates

    PubMed Central

    Al-Ayed, Mohamed Saeed Zayed; Asaad, Ahmed Morad; Qureshi, Mohamed Ansar; Attia, Hany Goda; AlMarrani, Abduljabbar Hadi

    2016-01-01

    Much effort has focused on examining the inhibitory effect of Salvadora persica (miswak) on oral microorganisms, but information concerning its antibacterial activity against other human pathogens, particularly multidrug resistant (MDR) isolates, is scarce. Therefore, this study aimed to assess the in vitro antibacterial activities of Salvadora persica L. extracts against 10 MDR bacterial clinical isolates other than oral pathogens. The antibacterial activity of aqueous and methanol miswak extracts was assessed using the agar dilution and minimum inhibitory concentration (MIC) methods. Overall, the 400 mg/mL of miswak extract was the most effective on all strains. The methanol extract exhibited a stronger antibacterial activity against Gram-negative (3.3–13.6 mm) than Gram-positive (1.8–8.3 mm) bacteria. The lowest MIC value was seen for E. coli (0.39, 1.56 µg/mL), followed by Streptococcus pyogenes (1.56 µg/mL). The highest MIC value (6.25, 12.5 µg/mL) was recorded for methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, and Stenotrophomonas maltophilia. This study demonstrates, for the first time, the moderate to strong antibacterial activity of miswak extracts against all tested MDR-pathogens. Methanol extract appears to be a potent antimicrobial agent that could be considered as complementary and alternative medicine against resistant pathogens. Further studies on a large number of MDR organisms are necessary to investigate and standardize the inhibitory effect of miswak extracts against these emerging pathogens. PMID:26904146

  1. Application of activated charcoal in the downstream processing of bacterial olefinic poly(3-hydroxyalkanoates).

    PubMed

    Wampfler, Bruno; Ramsauer, Thomas; Kehl, Karl; Zinn, Manfred; Thöny-Meyer, Linda

    2010-01-01

    Medium chain length poly(hydroxyalkanoates) (mcl-PHAs) are bacterial thermoplastic elastomers with a large potential in medical applications. The present study provides a novel process to isolate and purify poly([R]-3-hydroxy-omega-undecenoate-co-3-hydroxy-omega-nonenoate-co-3-hydroxy-omega-heptenoate) (PHUE) and poly([R]-3-hydroxy-omega-undecenoate-co-3-hydroxy-omega-nonenoate-co-3-hydroxyoctanoate-co-3-hydroxy-omega-heptenoate-co-3-hydroxyhexanoate) (PHOUE) from Pseudomonas putida species. Three different types of activated charcoal were compared with regard to their capability to selectively remove impurities. The product 'Charcoal activated, powder, pure' from Merck was found to be most suitable. Using ethyl acetate as solvent, the polyesters were extracted from freeze-dried biomass at room temperature and simultaneously purified by addition of activated charcoal at the beginning of the extraction. The period of extraction was one hour and the ratio solvent to biomass was 15:1 (vol/wt). After extraction, the solids were separated by pressure filtration through a metallic lace tissue. The filtrate was again passed through the previously accumulated filter cake, followed by a second filtration through a 0.45 microm membrane to remove finest coal particles. The resulting filtrate was concentrated, thus yielding polyesters whose quality and yield depended on the quantity of activated charcoal applied. For highly pure PHUE and PHOUE with low endotoxin levels, the optimum ratio of activated charcoal to solvent for extraction (V/V) was found to be 0.5 for PHUE and 0.25 for PHOUE. The yields with regard to the raw polymers amounted to 55 wt% for PHUE and 75 wt% for PHOUE, which are acceptable for polymers that can be used for medical applications. PMID:21197841

  2. Keratinocyte Production of Cathelicidin Provides Direct Activity against Bacterial Skin Pathogens

    PubMed Central

    Braff, Marissa H.; Zaiou, Mohamed; Fierer, Joshua; Nizet, Victor; Gallo, Richard L.

    2005-01-01

    Immune defense at an interface with the external environment reflects the functions of physical and chemical barriers provided by epithelial and immune cells. Resident epithelial cells, such as keratinocytes, produce numerous peptides with direct antimicrobial activity but also provide a physical barrier against invading pathogens and signal the recruitment of circulating immune cells, such as neutrophils. Antimicrobial peptides such as cathelicidin are produced constitutively by neutrophils and are inducible in keratinocytes in response to infection. The multiplicity of antimicrobial peptides and their cellular sources has resulted in an incomplete understanding of the role of cathelicidin production by epithelial cells in cutaneous immune defense. Therefore, this study sought to evaluate keratinocyte antimicrobial activity and the potential contribution of keratinocyte cathelicidin to host protection against two leading human skin pathogens. Wild-type mice and those with a targeted deletion of the cathelicidin gene, Cnlp, were rendered neutropenic prior to cutaneous infection. Interestingly, Cnlp-deficient mice remained more susceptible to group A streptococcus infection than mice with Cnlp intact, suggesting the involvement of epithelial cell-derived cathelicidin in host immune defense. Keratinocytes were then isolated in culture and found to inhibit the growth of Staphylococcus aureus, an effect that was partially dependent on their ability to synthesize and activate cathelicidin. Further, lentivirus-mediated delivery of activated human cathelicidin enhanced keratinocyte antimicrobial activity. Combined, these data illustrate the potential contribution of keratinocyte cathelicidin to the innate immune defense of skin against bacterial pathogens and highlight the need to consider epithelial antimicrobial function in the diagnosis and therapy of skin infection. PMID:16177355

  3. Diversity of active microbial communities subjected to long-term exposure to chemical contaminants along a 40-year-old sediment core.

    PubMed

    Kaci, Assia; Petit, Fabienne; Fournier, Matthieu; Cécillon, Sébastien; Boust, Dominique; Lesueur, Patrick; Berthe, Thierry

    2016-03-01

    In estuarine ecosystems, metallic and organic contaminants are mainly associated with fine grain sediments which settle on mudflats. Over time, the layers of sediment accumulate and are then transformed by diagenetic processes mainly controlled by microbial activity, recording the history of the estuary's chemical contamination. In an environment of this specific type, we investigated the evolution of the chemical contamination and the structure of both total and active microbial communities, based on PhyloChip analysis of a 4.6-m core corresponding to a 40-year sedimentary record. While the archaeal abundance remained constant along the core, a decrease by one order of magnitude in the bacterial abundance was observed with depth. Both total and active microbial communities were dominated by Proteobacteria, Actinobacteria, and Firmicutes in all sediment samples. Among Proteobacteria, alpha-Proteobacteria dominated both total (from 37 to 60 %) and metabolically active (from 19.7 to 34.6 %) communities, including the Rhizobiales, Rhodobacter, Caulobacterales, and Sphingomonadales orders. Co-inertia analysis revealed a relationship between polycyclic aromatic hydrocarbons, zinc and some polychlorobiphenyls concentrations, and the structure of total and active microbial communities in the oldest and most contaminated sediments (from 1970 to 1975), suggesting that long-term exposure to chemicals shaped the structure of the microbial community. PMID:25934230

  4. Surface-engineered core-shell nano-size ferrites and their antimicrobial activity

    SciTech Connect

    Baraliya, Jagdish D. Joshi, Hiren H.

    2014-04-24

    We report the results of biological study on core-shell structured MFe{sub 2}O{sub 4} (where M = Co, Mn, Ni) nanoparticles and influence of silica- DEG dual coating on their antimicrobial activity. Spherical MFe{sub 2}O{sub 4} nanoparticles were prepared via a Co-precipitation method. The microstructures and morphologies of these nanoparticles were studied by x-ray diffraction and FTIR. The antimicrobial activity study carried out in nutrient agar medium with addition of antimicrobial synthesis compound which is tested for its activity against different types of bacteria.

  5. Synthesis of new chalcone derivatives containing a rhodanine-3-acetic acid moiety with potential anti-bacterial activity.

    PubMed

    Chen, Zhen-Hua; Zheng, Chang-Ji; Sun, Liang-Peng; Piao, Hu-Ri

    2010-12-01

    With an intention to synergize the anti-bacterial activity of chalcones and rhodanine-3-acetic acid, several hybrid compounds possessing chalcone and rhodanine-3-acetic acid moieties were synthesized and tested for their anti-bacterial activity. Some compounds presented great anti-microbial activities against Gram-positive bacteria (including the multidrug-resistant clinical isolates). This class of compounds presented high potency against Staphylococcus aureus, among which the derivatives 5k with a MIC of 2 μg/mL was as active as the standard drug (norfloxacin) and less active than oxacillin. Compounds 5a-s did not inhibit the growth of Gram-negative bacteria Escherichia coli CCARM 1924 or E. coli CCARM 1356 at 64 μg/mL. PMID:20889240

  6. Methanotrophic activity and bacterial diversity in volcanic-geothermal soils at Pantelleria island (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-04-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils are source of methane, but also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission was previously estimated in about 2.5 t a-1. Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values up to 950 ng g-1 dry soil h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile and the maximum methane consumption was measured in the top-soil layer but values > 100 ng g-1 h-1 were maintained up to a depth of 15 cm. The highest consumption rate was measured at 37 °C, but a still recognizable consumption at 80 °C (> 20 ng g-1 h-1) was recorded. In order to estimate the bacterial diversity, total soil DNA was extracted from Favara Grande and analysed using a Temporal Temperature Gradient gel Electrophoresis (TTGE) analysis of the amplified bacterial 16S rRNA gene. The three soil samples were probed by PCR using standard proteobacterial primers and newly designed verrucomicrobial primers targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected in sites FAV2 and FAV3, but not in FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site FAV2 pointed out a high diversity of gammaproteobacterial methanotrophs distantly related to Methylococcus/Methylothermus genera and the presence of the newly discovered acido-thermophilic methanotrophs

  7. Systematically Altering Bacterial SOS Activity under Stress Reveals Therapeutic Strategies for Potentiating Antibiotics.

    PubMed

    Mo, Charlie Y; Manning, Sara A; Roggiani, Manuela; Culyba, Matthew J; Samuels, Amanda N; Sniegowski, Paul D; Goulian, Mark; Kohli, Rahul M

    2016-01-01

    The bacterial SOS response is a DNA damage repair network that is strongly implicated in both survival and acquired drug resistance under antimicrobial stress. The two SOS regulators, LexA and RecA, have therefore emerged as potential targets for adjuvant therapies aimed at combating resistance, although many open questions remain. For example, it is not well understood whether SOS hyperactivation is a viable therapeutic approach or whether LexA or RecA is a better target. Furthermore, it is important to determine which antimicrobials could serve as the best treatment partners with SOS-targeting adjuvants. Here we derived Escherichia coli strains that have mutations in either lexA or recA genes in order to cover the full spectrum of possible SOS activity levels. We then systematically analyzed a wide range of antimicrobials by comparing the mean inhibitory concentrations (MICs) and induced mutation rates for each drug-strain combination. We first show that significant changes in MICs are largely confined to DNA-damaging antibiotics, with strains containing a constitutively repressed SOS response impacted to a greater extent than hyperactivated strains. Second, antibiotic-induced mutation rates were suppressed when SOS activity was reduced, and this trend was observed across a wider spectrum of antibiotics. Finally, perturbing either LexA or RecA proved to be equally viable strategies for targeting the SOS response. Our work provides support for multiple adjuvant strategies, while also suggesting that the combination of an SOS inhibitor with a DNA-damaging antibiotic could offer the best potential for lowering MICs and decreasing acquired drug resistance. IMPORTANCE Our antibiotic arsenal is becoming depleted, in part, because bacteria have the ability to rapidly adapt and acquire resistance to our best agents. The SOS pathway, a widely conserved DNA damage stress response in bacteria, is activated by many antibiotics and has been shown to play central role in

  8. Systematically Altering Bacterial SOS Activity under Stress Reveals Therapeutic Strategies for Potentiating Antibiotics

    PubMed Central

    Mo, Charlie Y.; Manning, Sara A.; Roggiani, Manuela; Culyba, Matthew J.; Samuels, Amanda N.; Sniegowski, Paul D.; Goulian, Mark

    2016-01-01

    ABSTRACT The bacterial SOS response is a DNA damage repair network that is strongly implicated in both survival and acquired drug resistance under antimicrobial stress. The two SOS regulators, LexA and RecA, have therefore emerged as potential targets for adjuvant therapies aimed at combating resistance, although many open questions remain. For example, it is not well understood whether SOS hyperactivation is a viable therapeutic approach or whether LexA or RecA is a better target. Furthermore, it is important to determine which antimicrobials could serve as the best treatment partners with SOS-targeting adjuvants. Here we derived Escherichia coli strains that have mutations in either lexA or recA genes in order to cover the full spectrum of possible SOS activity levels. We then systematically analyzed a wide range of antimicrobials by comparing the mean inhibitory concentrations (MICs) and induced mutation rates for each drug-strain combination. We first show that significant changes in MICs are largely confined to DNA-damaging antibiotics, with strains containing a constitutively repressed SOS response impacted to a greater extent than hyperactivated strains. Second, antibiotic-induced mutation rates were suppressed when SOS activity was reduced, and this trend was observed across a wider spectrum of antibiotics. Finally, perturbing either LexA or RecA proved to be equally viable strategies for targeting the SOS response. Our work provides support for multiple adjuvant strategies, while also suggesting that the combination of an SOS inhibitor with a DNA-damaging antibiotic could offer the best potential for lowering MICs and decreasing acquired drug resistance. IMPORTANCE Our antibiotic arsenal is becoming depleted, in part, because bacteria have the ability to rapidly adapt and acquire resistance to our best agents. The SOS pathway, a widely conserved DNA damage stress response in bacteria, is activated by many antibiotics and has been shown to play central role

  9. Drivers shaping the diversity and biogeography of total and active bacterial communities in the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Zhao, Z.; Dai, M.; Jiao, N.

    2013-12-01

    Very few studies have been devoted to understanding microbial biogeography from the viewpoint of active versus total bacterial communities. Here, we examined the bacterial community along two transects, one from the inner Pearl River estuary to the open water of the South China Sea (SCS) and the other from the Luzon Strait to the SCS basin, using 454 pyrosequencing of the 16S rRNA and rDNA. Bacterial community composition was strongly correlated with environmental factors and weakly correlated with geographical distance between sites, although the diversity and biogeographic patterns differed substantially between the total and active communities. Compared to the total community, the active heterotrophic bacterial community displayed higher environmental sensitivity and a greater distance effect that was in fact mainly contributed by the active assemblage from deep waters. Taken together, the 16S rRNA versus rDNA relationships and community network models implied that the active heterotrophic bacteria, in high competition with each other, have high growth rates and high loss rates from predation, and hence are less-abundant in the SCS. Thereinto, most of the taxa act as specialists in the ecosystem and the others as generalists, which could cause some dispersal limitations such that some species could not become successfully established in the new location as they were moved through drift and, therefore, the active bacterial community could be determined to have a distinct distance-decay relationship. Altogether, our results supported the proposal that the current distributions of bacteria in the SCS were actually the result of both contemporary selection and historical drift processes.

  10. Identification of Active Bacterial Communities in Drinking Water Using 16S rRNA-Based Sequence Analyses

    EPA Science Inventory

    DNA-based methods have considerably increased our understanding of the bacterial diversity of water distribution systems (WDS). However, as DNA may persist after cell death, the use of DNA-based methods cannot be used to describe metabolically-active microbes. In contrast, intra...

  11. Molecular characterization of total and metabolically active bacterial communities of "white colonizations" in the Altamira Cave, Spain.

    PubMed

    Portillo, M Carmen; Saiz-Jimenez, Cesareo; Gonzalez, Juan M

    2009-01-01

    Caves with paleolithic paintings are influenced by bacterial development. Altamira Cave (Spain) contains some of the most famous paintings from the Paleolithic era. An assessment of the composition of bacterial communities that have colonized this cave represents a first step in understanding and potentially controlling their proliferation. In this study, areas showing colonization with uncolored microorganisms, referred to as "white colonizations", were analyzed. Microorganisms present in these colonizations were studied using DNA analysis, and those showing significant metabolic activity were detected in RNA-based RNA analysis. Bacterial community fingerprints were obtained both from DNA and RNA analyses, indicating differences between the microorganisms present and metabolically active in these white colonizations. Metabolically active microorganisms represented only a fraction of the total bacterial community present in the colonizations. 16S rRNA gene libraries were used to identify the major representative members of the studied communities. Proteobacteria constituted the most frequently found division both among metabolically active microorganisms (from RNA-based analysis) and those present in the community (from DNA analysis). Results suggest the existence of a huge variety of taxa in white colonizations of the Altamira Cave which represent a potential risk for the conservation of the cave and its paintings. PMID:18984039

  12. Bacterially mediated mineralization of vaterite

    NASA Astrophysics Data System (ADS)

    Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel

    2007-03-01

    Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.

  13. A bacterial ATP-dependent, enhancer binding protein that activates the housekeeping RNA polymerase

    PubMed Central

    Bowman, William C.; Kranz, Robert G.

    1998-01-01

    A commonly accepted view of gene regulation in bacteria that has emerged over the last decade is that promoters are transcriptionally activated by one of two general mechanisms. The major type involves activator proteins that bind to DNA adjacent to where the RNA polymerase (RNAP) holoenzyme binds, usually assisting in recruitment of the RNAP to the promoter. This holoenzyme uses the housekeeping ς70 or a related factor, which directs the core RNAP to the promoter and assists in melting the DNA near the RNA start site. A second type of mechanism involves the alternative sigma factor (called ς54 or ςN) that directs RNAP to highly conserved promoters. In these cases, an activator protein with an ATPase function oligomerizes at tandem sites far upstream from the promoter. The nitrogen regulatory protein (NtrC) from enteric bacteria has been the model for this family of activators. Activation of the RNAP/ς54 holoenzyme to form the open complex is mediated by the activator, which is tethered upstream. Hence, this class of protein is sometimes called the enhancer binding protein family or the NtrC class. We describe here a third system that has properties of each of these two types. The NtrC enhancer binding protein from the photosynthetic bacterium, Rhodobacter capsulatus, is shown in vitro to activate the housekeeping RNAP/ς70 holoenzyme. Transcriptional activation by this NtrC requires ATP binding but not hydrolysis. Oligomerization at distant tandem binding sites on a supercoiled template is also necessary. Mechanistic and evolutionary questions of these systems are discussed. PMID:9637689

  14. Chronic bacterial infection activates autoreactive B cells and induces isotype switching and autoantigen-driven mutations.

    PubMed

    Jung, Sophie; Schickel, Jean-Nicolas; Kern, Aurélie; Knapp, Anne-Marie; Eftekhari, Pierre; Da Silva, Sylvia; Jaulhac, Benoît; Brink, Robert; Soulas-Sprauel, Pauline; Pasquali, Jean-Louis; Martin, Thierry; Korganow, Anne-Sophie

    2016-01-01

    The links between infections and the development of B-cell-mediated autoimmune diseases are still unclear. In particular, it has been suggested that infection-induced stimulation of innate immune sensors can engage low affinity autoreactive B lymphocytes to mature and produce mutated IgG pathogenic autoantibodies. To test this hypothesis, we established a new knock-in mouse model in which autoreactive B cells could be committed to an affinity maturation process. We show that a chronic bacterial infection allows the activation of such B cells and the production of nonmutated IgM autoantibodies. Moreover, in the constitutive presence of their soluble antigen, some autoreactive clones are able to acquire a germinal center phenotype, to induce Aicda gene expression and to introduce somatic mutations in the IgG heavy chain variable region on amino acids forming direct contacts with the autoantigen. Paradoxically, only lower affinity variants are detected, which strongly suggests that higher affinity autoantibodies secreting B cells are counterselected. For the first time, we demonstrate in vivo that a noncross-reactive infectious agent can activate and induce autoreactive B cells to isotype switching and autoantigen-driven mutations, but on a nonautoimmune background, tolerance mechanisms prevent the formation of consequently dangerous autoimmunity. PMID:26474536

  15. A Coexisting Fungal-Bacterial Community Stabilizes Soil Decomposition Activity in a Microcosm Experiment

    PubMed Central

    Ushio, Masayuki; Miki, Takeshi; Balser, Teri C.

    2013-01-01

    How diversity influences the stability of a community function is a major question in ecology. However, only limited empirical investigations of the diversity–stability relationship in soil microbial communities have been undertaken, despite the fundamental role of microbial communities in driving carbon and nutrient cycling in terrestrial ecosystems. In this study, we conducted a microcosm experiment to investigate the relationship between microbial diversity and stability of soil decomposition activities against changes in decomposition substrate quality by manipulating microbial community using selective biocides. We found that soil respiration rates and degradation enzyme activities by a coexisting fungal and bacterial community (a taxonomically diverse community) are more stable against changes in substrate quality (plant leaf materials) than those of a fungi-dominated or a bacteria-dominated community (less diverse community). Flexible changes in the microbial community composition and/or physiological state in the coexisting community against changes in substrate quality, as inferred by the soil lipid profile, may be the mechanism underlying this positive diversity–stability relationship. Our experiment demonstrated that the previously found positive diversity–stability relationship could also be valid in the soil microbial community. Our results also imply that the functional/taxonomic diversity and community ecology of soil microbes should be incorporated into the context of climate–ecosystem feedbacks. Changes in substrate quality, which could be induced by climate change, have impacts on decomposition process and carbon dioxide emission from soils, but such impacts may be attenuated by the functional diversity of soil microbial communities. PMID:24260368

  16. The anti-bacterial activity of titanium-copper sintered alloy against Porphyromonas gingivalis in vitro.

    PubMed

    Bai, Bing; Zhang, Erlin; Liu, Junchao; Zhu, Jingtao

    2016-01-01

    This study investigates the anti-bacterial property of Ti-Cu sintered alloys against Porphyromonas gingivalis. The anti-anaerobic property of Ti-Cu sintered alloys against P. gingivalis was investigated by antibacterial activity test, DNA measurement, DAPI staining and morphology observation. The antibacterial rates of the Ti-5Cu against P. gingivalis after 18 and 24 h incubation were 36.04 and 54.39%, and those of Ti-10Cu were 68.69 and 75.39%, which were lower than their anti-aerobic abilities. The concentration of P. gingivalis DNA gradually decreased with the increasing Cu content, which was nearly 50% after 24 h incubation on Ti-10Cu. SEM results showed that the shape of P. gingivalis changed and the bacteria broke apart with the addition of Cu and the extension of the culture time. Ti-Cu sintered alloys could not only kill anaerobic bacteria but also reduce the activity of the survived bacteria. The anti-anaerobic mechanism was thought to be in associated with the Cu ion released from Ti-Cu alloy. PMID:27477233

  17. [Activity of frequently used disinfectants and antiseptics against nosocomial bacterial types].

    PubMed

    Ozkurt, Zülal; Altoparlak, Ulkü; Erol, Serpil; Celebi, Selahattin

    2003-01-01

    In this study, bactericidal activity of widely used disinfectants and antiseptics (glutaraldehyde, laurylbispropylidentriamin 5 g and benzalkoniumchlorid 20 g, polyvinylpyrolidon iodine, benzalkonium chloride and sodium hypochloride) against some nosocomial bacterial isolates were investigated by qualitative and quantitative suspension test methods. One methicillin-resistant Staphylococcus aureus (MRSA), 6 multi drug-resistant Gram-negative hospital isolates (Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloaca, Klebsiella pneumoniae, Citrobacter diversus, Serratia marcescens) and 3 standard strains of American Type Culture Collection (ATCC) bacteria (S. aureus, P. aeruginosa, E. coli) were tested against three different concentrations of disinfectants of which, manufacturer's recommended use-dilution, 1/2 and 1/4 of those recommended dilutions. All tested disinfectants were found effective in all three concentrations against nosocomial isolates in five minutes, by using both qualitative and quantitative suspension methods. When the test was repeated with albumine, bactericidal activities of disinfectants were found the same. Our findings showed that these disinfectants can be still used in safe for the sterilization in hospital, and routine disinfection protocols do not need to be alerted. PMID:14593898

  18. Crowding Modulates the Conformation, Affinity, and Activity of the Components of the Bacterial Disaggregase Machinery.

    PubMed

    Celaya, Garbiñe; Fernández-Higuero, José Angel; Martin, Ianire; Rivas, Germán; Moro, Fernando; Muga, Arturo

    2016-06-01

    Chaperone-mediated protein aggregate reactivation is a complex reaction that depends on the sequential association of molecular chaperones on their interaction with protein aggregates and on substrate refolding. This process could be modulated by the highly crowded intracellular environment, which is known to affect protein conformational change, enzymatic activity, and protein-protein interactions. Here, we report that molecular crowding shapes the chaperone activity of bacterial disaggregase composed of the DnaK system (DnaK, DnaJ, and GrpE) and the molecular motor ClpB. A combination of biophysical and biochemical methods shows that the excluded volume conditions modify the conformation of DnaK and DnaJ without affecting that of GrpE. These crowding-induced conformational rearrangements activate DnaK, enhance the affinity of DnaK for DnaJ, but not for GrpE, and increase the sensitivity of the chaperone activity to cochaperone concentration, explaining the tight control of their relative intracellular amounts. Furthermore, crowding-mediated disordering of the G/F domain of DnaJ facilitates the reversible formation of intermolecular DnaJ conglomerates. These assemblies could drive the formation of Hsp70 clusters at the aggregate surface with the consequent enhancement of the disaggregation efficiency through their coordinated action via entropic pulling. Finally, crowding helps ClpB to outcompete GrpE for DnaK binding, a key aspect of DnaK/ClpB cooperation given the low affinity of the disaggregase for DnaK. Excluded volume conditions promote the formation of the bichaperone complex that disentangles aggregates, enhancing the efficiency of the disaggregation reaction. PMID:27133933

  19. The activated sludge ecosystem contains a core community of abundant organisms

    PubMed Central

    Saunders, Aaron M; Albertsen, Mads; Vollertsen, Jes; Nielsen, Per H

    2016-01-01

    Understanding the microbial ecology of a system requires that the observed population dynamics can be linked to their metabolic functions. However, functional characterization is laborious and the choice of organisms should be prioritized to those that are frequently abundant (core) or transiently abundant, which are therefore putatively make the greatest contribution to carbon turnover in the system. We analyzed the microbial communities in 13 Danish wastewater treatment plants with nutrient removal in consecutive years and a single plant periodically over 6 years, using Illumina sequencing of 16S ribosomal RNA amplicons of the V4 region. The plants contained a core community of 63 abundant genus-level operational taxonomic units (OTUs) that made up 68% of the total reads. A core community consisting of abundant OTUs was also observed within the incoming wastewater to three plants. The net growth rate for individual OTUs was quantified using mass balance, and it was found that 10% of the total reads in the activated sludge were from slow or non-growing OTUs, and that their measured abundance was primarily because of immigration with the wastewater. Transiently abundant organisms were also identified. Among them the genus Nitrotoga (class Betaproteobacteria) was the most abundant putative nitrite oxidizer in a number of activated sludge plants, which challenges previous assumptions that Nitrospira (phylum Nitrospirae) are the primary nitrite-oxidizers in activated sludge systems with nutrient removal. PMID:26262816

  20. (129)I record of nuclear activities in marine sediment core from Jiaozhou Bay in China.

    PubMed

    Fan, Yukun; Hou, Xiaolin; Zhou, Weijian; Liu, Guangshan

    2016-04-01

    Iodine-129 has been used as a powerful tool for environmental tracing of human nuclear activities. In this work, a sediment core collected from Jiaozhou Bay, the east coast of China, in 2002 was analyzed for (129)I to investigate the influence of human nuclear activities in this region. Significantly enhanced (129)I level was observed in upper 70 cm of the sediment core, with peak values in the layer corresponding to 1957, 1964, 1974, 1986, and after 1990. The sources of (129)I and corresponding transport processes in this region are discussed, including nuclear weapons testing at the Pacific Proving Grounds, global fallout from a large numbers of nuclear weapon tests in 1963, the climax of Chinese nuclear weapons testing in the early 1970s, the Chernobyl accident in 1986, and long-distance dispersion of European reprocessing derived (129)I. The very well (129)I records of different human nuclear activities in the sediment core illustrate the potential application of (129)I in constraining ages and sedimentation rates of the recent sediment. The releases of (129)I from the European nuclear fuel reprocessing plants at La Hague (France) and Sellafield (UK) were found to dominate the inventory of (129)I in the Chinese sediments after 1990, not only the directly atmospheric releases of these reprocessing plants, but also re-emission of marine discharged (129)I of these reprocessing plants in the highly contaminated European seas. PMID:26821329

  1. 9,400 years of cosmic radiation and solar activity from ice cores and tree rings

    PubMed Central

    Steinhilber, Friedhelm; Beer, Jürg; Brunner, Irene; Christl, Marcus; Fischer, Hubertus; Heikkilä, Ulla; Kubik, Peter W.; Mann, Mathias; McCracken, Ken G.; Miller, Heinrich; Miyahara, Hiroko; Oerter, Hans

    2012-01-01

    Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such as 10Be and 14C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although records from different archives basically agree, they also show some deviations during certain periods. So far most reconstructions were based on only one single radionuclide record, which makes detection and correction of these deviations impossible. Here we combine different 10Be ice core records from Greenland and Antarctica with the global 14C tree ring record using principal component analysis. This approach is only possible due to a new high-resolution 10Be record from Dronning Maud Land obtained within the European Project for Ice Coring in Antarctica in Antarctica. The new cosmic radiation record enables us to derive total solar irradiance, which is then used as a proxy of solar activity to identify the solar imprint in an Asian climate record. Though generally the agreement between solar forcing and Asian climate is good, there are also periods without any coherence, pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. The newly derived records have the potential to improve our understanding of the solar dynamics and to quantify the solar influence on climate. PMID:22474348

  2. Inhibitory Activities of Gatifloxacin (AM-1155), a Newly Developed Fluoroquinolone, against Bacterial and Mammalian Type II Topoisomerases

    PubMed Central

    Takei, Masaya; Fukuda, Hideyuki; Yasue, Tokutaro; Hosaka, Masaki; Oomori, Yasuo

    1998-01-01

    We determined the inhibitory activities of gatifloxacin against Staphylococcus aureus topoisomerase IV, Escherichia coli DNA gyrase, and HeLa cell topoisomerase II and compared them with those of several quinolones. The inhibitory activities of quinolones against these type II topoisomerases significantly correlated with their antibacterial activities or cytotoxicities (correlation coefficient [r] = 0.926 for S. aureus, r = 0.972 for E. coli, and r = 0.648 for HeLa cells). Gatifloxacin possessed potent inhibitory activities against bacterial type II topoisomerases (50% inhibitory concentration [IC50] = 13.8 μg/ml for S. aureus topoisomerase IV; IC50 = 0.109 μg/ml for E. coli DNA gyrase) but the lowest activity against HeLa cell topoisomerase II (IC50 = 265 μg/ml) among the quinolones tested. There was also a significant correlation between the inhibitory activities of quinolones against S. aureus topoisomerase IV and those against E. coli DNA gyrase (r = 0.969). However, the inhibitory activity against HeLa cell topoisomerase II did not correlate with that against either bacterial enzyme. The IC50 of gatifloxacin for HeLa cell topoisomerase II was 19 and was more than 2,400 times higher than that for S. aureus topoisomerase IV and that for E. coli DNA gyrase. These ratios were higher than those for other quinolones, indicating that gatifloxacin possesses a higher selectivity for bacterial type II topoisomerases. PMID:9756776

  3. Bacterial assembly and temporal dynamics in activated sludge of a full-scale municipal wastewater treatment plant

    PubMed Central

    Ju, Feng; Zhang, Tong

    2015-01-01

    Understanding environmental and biological influences on the dynamics of microbial communities has received great attention in microbial ecology. Here, utilizing large time-series 16S rRNA gene data, we show that in activated sludge of an environmentally important municipal wastewater treatment plant, 5-year temporal dynamics of bacterial community shows no significant seasonal succession, but is consistent with deterministic assemblage by taxonomic relatedness. Biological interactions are dominant drivers in determining the bacterial community assembly, whereas environmental conditions (mainly sludge retention time and inorganic nitrogen) partially explain phylogenetic and quantitative variances and indirectly influence bacterial assembly. We demonstrate a correlation-based statistical method to integrate bacterial association networks with their taxonomic affiliations to predict community-wide co-occurrence and co-exclusion patterns. The results show that although taxonomically closely related bacteria tend to positively co-occur (for example, out of a cooperative relationship), negative co-excluding correlations are deterministically observed between taxonomically less related species, probably implicating roles of competition in determining bacterial assembly. Overall, disclosures of the positive and negative species–species relations will improve our understanding of ecological niches occupied by unknown species and help to predict their biological functions in ecosystems. PMID:25180966

  4. Adenoviral augmentation of elafin protects the lung against acute injury mediated by activated neutrophils and bacterial infection.

    PubMed

    Simpson, A J; Wallace, W A; Marsden, M E; Govan, J R; Porteous, D J; Haslett, C; Sallenave, J M

    2001-08-01

    During acute pulmonary infection, tissue injury may be secondary to the effects of bacterial products or to the effects of the host inflammatory response. An attractive strategy for tissue protection in this setting would combine antimicrobial activity with inhibition of human neutrophil elastase (HNE), a key effector of neutrophil-mediated tissue injury. We postulated that genetic augmentation of elafin (an endogenous inhibitor of HNE with intrinsic antimicrobial activity) could protect the lung against acute inflammatory injury without detriment to host defense. A replication-deficient adenovirus encoding elafin cDNA significantly protected A549 cells against the injurious effects of both HNE and whole activated human neutrophils in vitro. Intratracheal replication-deficient adenovirus encoding elafin cDNA significantly protected murine lungs against injury mediated by Pseudomonas aeruginosa in vivo. Genetic augmentation of elafin therefore has the capacity to protect the lung against the injurious effects of both bacterial pathogens resistant to conventional antibiotics and activated neutrophils. PMID:11466403

  5. An annual survey of bacterial production, respiration and ectoenzyme activity in coastal NW Mediterranean waters: temperature and resource controls.

    PubMed

    Céa, B; Lefèvre, D; Chirurgien, L; Raimbault, P; Garcia, N; Charrière, B; Grégori, G; Ghiglione, J F; Barani, A; Lafont, M; Van Wambeke, F

    2015-09-01

    We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity (phos) and ectoaminopeptidase activity (prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 μg dm(-3), NO3 = 0.55 μmol dm(-3) and PO4 = 0.04 μmol dm(-3)). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 μg C dm-(3) h-(1) and bacterial growth efficiency varied from 1 to 39%, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem. PMID:25217279

  6. In Situ Synthesis of Catalytic Active Au Nanoparticles onto Gibbsite-Polydopamine Core-Shell Nanoplates.

    PubMed

    Cao, Jie; Mei, Shilin; Jia, He; Ott, Andreas; Ballauff, Matthias; Lu, Yan

    2015-09-01

    We report a facile method to synthesize anisotropic platelike gibbsite-polymer core-shell particles. Dopamine is self-polymerized on the surface of gibbsite nanoplates and forms a homogeneous layer on it. Transmission electron microscopy characterization of the resulting latexes demonstrates the formation of well-defined platelike core-shell particles. Reaction time and ultrasonification are found to be important factors to control the thickness of the polymer shell and avoid aggregation. Good control over the platelike morphology and 100% encapsulation efficiency have been achieved via this novel route. The resulting well-defined gibbsite-polydamine (G-PDA) core-shell nanoplates show excellent colloidal stability and can form opal-like columnar crystal with iridescent Bragg reflection after modest centrifugation. In addition, G-PDA core-shell nanoplates can serve both as reductant and stabilizer for the generation of Au nanoparticles (NPs) in situ. Au NPs with tunable size have been formed on the G-PDA particle surface, which show efficient catalytic activity for the reduction of 4-nitrophenol and Rhodamine B (RhB) in the presence of borohydride. Such nanocatalysts can be easily deposited on silicon substrate by spin-coating due to the large contact area of platelike G-PDA particles and the strong adhesive behavior of the PDA layer. The substrate-deposited nanocatalyst can be easily recycled which show excellent reusability for the reduction of RhB. PMID:26266398

  7. Bacterial biomass, metabolic state, and activity in stream sediments: relation to environmental variables and multiple assay comparisons.

    PubMed

    Bott, T L; Kaplan, L A

    1985-08-01

    Bacterial biomass, metabolic condition, and activity were measured over a 16-month period in the surface sediments of the following four field sites with differing dissolved organic matter regimes: a woodlot spring seep, a meadow spring seep, a second-order stream, and a third-order stream. Total bacterial biomass was measured by lipid phosphate and epifluorescence microscopic counts (EMC), and viable biomass was measured by C most probable number, EMC with 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride reduction, and ATP. Bacterial metabolic condition was determined from the percentage of respiring cells, poly-beta-hydroxybutyrate concentrations, and adenylate energy charge. Activity measures included C-lipid synthesis, P-phospholipid synthesis, the rate of uptake of algal lysate dissolved organic carbon, and respiration, from which biosynthesis was calculated (dissolved organic carbon uptake corrected for respiration). Total bacterial biomass (from EMC) ranged from 0.012 to 0.354 mug of C/mg of dry sediment and was usually lowest in the third-order stream. The percentage of cells respiring was less than 25% at all sites, indicating that most bacteria were dormant or dead. Adenylate energy charge was measured only in the third-order stream and was uniformly low. Poly-beta-hydroxybutyrate concentrations were greater in the woodlot spring seep than in the second- and third-order streams. Uptake of algal lysate dissolved organic carbon ranged from undetectable levels to 166 mg of C . m . h. Little community respiration could be attributed to algal lysate metabolism. Phospholipid synthesis ranged from 0.006 to 0.354 pmol . mg of dry sediment . h. Phospholipid synthesis rates were used to estimate bacterial turnover at the study sites. An estimated 375 bacterial generations per year were produced in the woodlot spring seep, and 67 per year were produced in the third-order stream. PMID:16346867

  8. Novel osmotically induced antifungal chitinases and bacterial expression of an active recombinant isoform.

    PubMed Central

    Yun, D J; D'Urzo, M P; Abad, L; Takeda, S; Salzman, R; Chen, Z; Lee, H; Hasegawa, P M; Bressan, R A

    1996-01-01

    NaCl (428 mM)-adapted tobacco (Nicotiana tabacum L. var Wisconsin 38) cells accumulate and secrete several antifungal chitinases. The predominant protein secreted to the culture medium was a 29-kD peptide that, based on internal amino acid sequence, was determined to be a class II acidic chitinase with similarity to PR-Q. The four predominant chitinases (T1, T2, T3, and T4) that accumulated intracellularly in 428 mM NaCl-adapted cells were purified. Based on N-terminal sequence analyses, two of these were identified as class I chitinase isoforms, one similar to the N. tomentosiformis (H. Shinshi, J.M. Neuhaus, J. Ryals, F. Meins [1990] Plant Mol Biol 14:357-368) protein (T1) and the other homologous to the N. sylvestris (Y. Fukuda, M. Ohme, H. Shinshi [1991] Plant Mol Biol 16:1-10) protein (T2). The other two proteins (T3 and T4) were determined to be novel chitinases that have sequence similarity with class I chitinases, but each lacks a chitin-binding domain. All four chitinases inhibited Fusarium oxysporum f. sp. lycopersici and Trichoderma longibrachiatum hyphal growth in vitro, although the isoforms containing a chitin-binding domain were somewhat more active. Conditions were established for the successful expression of soluble and active bacterial recombinant T2. Expression of soluble recombinant T2 was achieved when isopropyl beta-D-thiogalactopyranoside induction occurred at 18 degrees C but not at 25 or 37 degrees C. The purified recombinant protein exhibited antifungal activity comparable to a class I chitinase purified from NaCl-adapted tobacco cells. PMID:8756502

  9. Human and climate impacts on Holocene fire activity recorded in polar and mountain ice cores

    NASA Astrophysics Data System (ADS)

    Kehrwald, Natalie; Zennaro, Piero; Kirchgeorg, Torben; Li, Quanlian; Wang, Ninglian; Power, Mitchell; Zangrando, Roberta; Gabrielli, Paolo; Thompson, Lonnie; Gambaro, Andrea; Barbante, Carlo

    2014-05-01

    Fire is one of the major influences of biogeochemical change on local to hemispheric scales through emitting greenhouse gases, altering atmospheric chemistry, and changing primary productivity. Levoglucosan (1,6-anhydro-β-D-glucopyranose) is a specific molecular that can only be produced by cellulose burning at temperatures > 300°C, comprises a major component of smoke plumes, and can be transported across > 1000 km distances. Levoglucosan is deposited on and archived in glaciers over glacial interglacial cycles resulting in pyrochemical evidence for exploring interactions between fire, climate and human activity. Ice core records provide records of past biomass burning from regions of the world with limited paleofire data including polar and low-latitude, high-altitude regions. Here, we present Holocene fire activity records from the NEEM, Greenland (77° 27'N; 51° 3'W; 2454 masl), EPICA Dome C, Antarctica (75° 06'S; 123° 21'E; 3233 masl), Kilimanjaro, Tanzania (3° 05'S, 21.2° E, 5893 masl) and the Muztagh, China (87.17° E; 36.35° N; 5780 masl ice cores. The NEEM ice core reflects boreal fire activity from both North American and Eurasian sources. Temperature is the dominant control of NEEM levoglucosan flux over decadal to millennial time scales, while droughts influence fire activity over sub-decadal timescales. Our results demonstrate the prominence of Siberian fire sources during intense multiannual droughts. Unlike the NEEM core, which incorporates the largest land masses in the world as potential fire sources, EPICA Dome C is located far from any possible fire source. However, EPICA Dome C levoglucosan concentrations are consistently above detection limits and demonstrate a substantial 1000-fold increase in fire activity beginning approximately 800 years ago. This significant and sustained increase coincides with Maori arrival and dispersal in New Zealand augmented by later European arrival in Australia. The EPICA Dome C levoglucosan profile is

  10. The influence of bacterial-humus preparations on the biological activity of soils polluted with oil products and heavy metals

    NASA Astrophysics Data System (ADS)

    Kozlova, E. N.; Stepanov, A. L.; Lysak, L. V.

    2015-04-01

    The influence of bacterial-humus preparations based on Gumigel ( Agrosintez Company) on the biological activity of soddy-podzolic soil polluted with Pb(CH3COO)2 and gasoline was studied in a model experiment. Some indicators of biological activity are shown to depend on soil pollution to different extents. The process of nitrogen fixation and the activity of dehydrogenase and phosphatase were mostly inhibited by Pb(CH3COO)2 and gasoline. Gasoline compared to Pb(CH3COO)2 inhibited the soil biological activity to a greater extent. The bacterial-humus preparations exerted a significant positive effect on the biological activity of the polluted soils manifested in the increase of the total number of bacteria and of the enzyme activity (1.5-5.0 times), in the intensification of nitrogen fixation and denitrification (3-8 times), as well as in the increase in the biomass of the plants grown (1.5-2.0 times). The application of bacterial suspensions of pure cultures or the microbial complex without the preparations of humic acids did not always give a positive effect.

  11. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica).

    PubMed

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-05-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  12. Modelling and analysis of bacterial tracks suggest an active reorientation mechanism in Rhodobacter sphaeroides

    PubMed Central

    Rosser, Gabriel; Baker, Ruth E.; Armitage, Judith P.; Fletcher, Alexander G.

    2014-01-01

    Most free-swimming bacteria move in approximately straight lines, interspersed with random reorientation phases. A key open question concerns varying mechanisms by which reorientation occurs. We combine mathematical modelling with analysis of a large tracking dataset to study the poorly understood reorientation mechanism in the monoflagellate species Rhodobacter sphaeroides. The flagellum on this species rotates counterclockwise to propel the bacterium, periodically ceasing rotation to enable reorientation. When rotation restarts the cell body usually points in a new direction. It has been assumed that the new direction is simply the result of Brownian rotation. We consider three variants of a self-propelled particle model of bacterial motility. The first considers rotational diffusion only, corresponding to a non-chemotactic mutant strain. Two further models incorporate stochastic reorientations, describing ‘run-and-tumble’ motility. We derive expressions for key summary statistics and simulate each model using a stochastic computational algorithm. We also discuss the effect of cell geometry on rotational diffusion. Working with a previously published tracking dataset, we compare predictions of the models with data on individual stopping events in R. sphaeroides. This provides strong evidence that this species undergoes some form of active reorientation rather than simple reorientation by Brownian rotation. PMID:24872500

  13. Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

    PubMed Central

    Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

    1983-01-01

    The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study. PMID:6639023

  14. Magnetic Measurements of Bacterial Activity in Mid Oceanic Ridge Basalt Samples.

    NASA Astrophysics Data System (ADS)

    Carlut, J.; Horen, H.; Brunet, F.; Janots, D.; Pozzi, J.

    2004-12-01

    Magnetic properties of the young oceanic crust gives insights on the 3D structure at ridges axis and on variations of the Earth's magnetic field. Accurate interpretations depend on our understanding of the magnetic stability of titanomagnetite crystals carrying the magnetic signal. The mean remanent intensity of young ocean basalts shows significant variations with age and it has been suggested that rapid chemical alteration of titanomagnetite could be responsible. Ubiquitous presence of bacteria in deep marine environment and their ability to interact with iron oxides suggest a possible important impact of these life forms on the stability of titanomagnetites. In vivo experiments have been conducted on more than 15 fresh lava macro samples with a batch of selected sulfate reducing bacteria of the desulfovibrio genus, relevant to the deep biosphere. Remanent magnetization of samples was measured at regular time interval, in addition to more complete magnetic and chemical characterization at beginning and end of experiments. After a few months results show a significant contribution of bacterial activity on magnetic properties of samples, in particular a well defined drop in remanence. Our results suggest a strong impact of bacteria on the alteration rate of iron oxides carrying the magnetic signal within the oceanic crust.

  15. A Catalytic DNA Activated by a Specific Strain of Bacterial Pathogen.

    PubMed

    Shen, Zhifa; Wu, Zaisheng; Chang, Dingran; Zhang, Wenqing; Tram, Kha; Lee, Christine; Kim, Peter; Salena, Bruno J; Li, Yingfu

    2016-02-01

    Pathogenic strains of bacteria are known to cause various infectious diseases and there is a growing demand for molecular probes that can selectively recognize them. Here we report a special DNAzyme (catalytic DNA), RFD-CD1, that shows exquisite specificity for a pathogenic strain of Clostridium difficile (C. difficile). RFD-CD1 was derived by an in vitro selection approach where a random-sequence DNA library was allowed to react with an unpurified molecular mixture derived from this strain of C. difficle, coupled with a subtractive selection strategy to eliminate cross-reactivities to unintended C. difficile strains and other bacteria species. RFD-CD1 is activated by a truncated version of TcdC, a transcription factor, that is unique to the targeted strain of C. difficle. Our study demonstrates for the first time that in vitro selection offers an effective approach for deriving functional nucleic acid probes that are capable of achieving strain-specific recognition of bacterial pathogens. PMID:26676768

  16. Characterization of airborne ice-nucleation-active bacteria and bacterial fragments

    NASA Astrophysics Data System (ADS)

    Šantl-Temkiv, Tina; Sahyoun, Maher; Finster, Kai; Hartmann, Susan; Augustin-Bauditz, Stefanie; Stratmann, Frank; Wex, Heike; Clauss, Tina; Nielsen, Niels Woetmann; Sørensen, Jens Havskov; Korsholm, Ulrik Smith; Wick, Lukas Y.; Karlson, Ulrich Gosewinkel

    2015-05-01

    Some bacteria have the unique capacity of synthesising ice-nucleation-active (INA) proteins and exposing them at their outer membrane surface. As INA bacteria enter the atmosphere, they may impact the formation of clouds and precipitation. We studied members of airborne bacterial communities for their capacity to catalyse ice formation and we report on the excretion of INA proteins by airborne Pseudomonas sp. We also observed for the first time that INA biological fragments <220 nm were present in precipitation samples (199 and 482 INA fragments per L of precipitation), which confirms the presence of submicron INA biological fragments in the atmosphere. During 14 precipitation events, strains affiliated with the genus Pseudomonas, which are known to carry ina genes, were dominant. A screening for INA properties revealed that ∼12% of the cultivable bacteria caused ice formation at ≤-7 °C. They had likely been emitted to the atmosphere from terrestrial surfaces, e.g. by convective transport. We tested the ability of isolated INA strains to produce outer membrane vesicles and found that two isolates could do so. However, only very few INA vesicles were released per INA cell. Thus, the source of the submicron INA proteinaceous particles that we detected in the atmosphere remains to be elucidated.

  17. Magnetic Monitoring and Characterization at the Nanoscale of Bacterial Activity in Mid Oceanic Ridge Basalt Samples

    NASA Astrophysics Data System (ADS)

    Carlut, J.; Benzerara, K.; Horen, H.; Baronnet, A.

    2011-12-01

    Microbial communities have been shown over the last few years to be a significant component of the sub-sea floor crustal environment. The ubiquitous presence of these life forms suggests an important chemical impact on the host rocks. Among the diverse species, sulfate-reducing bacteria have been suggested, based on sulfur isotope studies, to be a major actor of the oceanic rocks alteration. Laboratory experiments were thus conducted on basalts from the East Pacific Ridge incubated with model sulfate-reducing bacteria. Results show that such bacteria can have a strong impact on the alteration rate of iron oxides carrying the magnetic signal of oceanic rocks. To some extent microbial processes can thus play a role in the decrease of sea floor magnetic signal. Such findings also open ways for the remote monitoring of bacterial activity through magnetic measurements. In order to gain insights on the mechanisms involved we characterized alteration features of iron oxides at the nanoscale in laboratory bio-altered samples and natural samples. We used a combination of scanning electron microscope, focused ion beam milling, ion beam thinning, transmission electron microscopy and scanning transmission X-ray microscopy. Some of the iron oxide crystals from these samples show singular alteration rims mostly composed of Fe and S and measuring a few nanometers in thickness. These observations contribute to understand the potential role of microbes in the alteration of the oceanic crust and possible impact on the magnetic signal.

  18. Strategies for the recovery of active proteins through refolding of bacterial inclusion body proteins

    PubMed Central

    Vallejo, Luis Felipe; Rinas, Ursula

    2004-01-01

    Recent advances in generating active proteins through refolding of bacterial inclusion body proteins are summarized in conjunction with a short overview on inclusion body isolation and solubilization procedures. In particular, the pros and cons of well-established robust refolding techniques such as direct dilution as well as less common ones such as diafiltration or chromatographic processes including size exclusion chromatography, matrix- or affinity-based techniques and hydrophobic interaction chromatography are discussed. Moreover, the effect of physical variables (temperature and pressure) as well as the presence of buffer additives on the refolding process is elucidated. In particular, the impact of protein stabilizing or destabilizing low- and high-molecular weight additives as well as micellar and liposomal systems on protein refolding is illustrated. Also, techniques mimicking the principles encountered during in vivo folding such as processes based on natural and artificial chaperones and propeptide-assisted protein refolding are presented. Moreover, the special requirements for the generation of disulfide bonded proteins and the specific problems and solutions, which arise during process integration are discussed. Finally, the different strategies are examined regarding their applicability for large-scale production processes or high-throughput screening procedures. PMID:15345063

  19. Anti-bacterial and anti-biofilm activity of probiotic bacteria against oral pathogens.

    PubMed

    Ben Taheur, Fadia; Kouidhi, Bochra; Fdhila, Kais; Elabed, Hamouda; Ben Slama, Rihab; Mahdouani, Kacem; Bakhrouf, Amina; Chaieb, Kamel

    2016-08-01

    In this study, three lactic acid bacteria (LAB), isolated from barley, traditional dried meat and fermented olive were characterized and tested for their anti-bacterial and anti-biofilm activities against oral bacteria. Our results revealed that the tested LAB were γ-hemolytic and were susceptible to four antibiotics. All the strains were resistant to low pH, bile salt, pepsin and pancreatin. Furthermore, FB2 displayed a high aut-oaggregative phenotype (99.54%) while FF2 exhibited the best co-aggregation rate. Concerning the microbial adhesion to solvent, FB2 was the most hydrophobic strain (data obtained with chloroform and n-hexadecane). In addition Pediococcus pentosaceus FB2 and Lactobacillus brevis FF2 displayed a significant inhibitory effect against Streptococcus salivarius B468 (MIC = 10%). Moreover the selected strains were able to inhibit biofilm formation of Bacillus cereus ATCC14579 (MBIC50 = 28.16%) and S. salivarius B468 (MBIC50 = 42.28%). The selected LAB could be considered as candidate probiotics for further application in functional food and mainly in the prevention of oral diseases. PMID:27317856

  20. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica) †

    PubMed Central

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-01-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  1. Antimicrobial Activity of Heterotrophic Bacterial Communities from the Marine Sponge Erylus discophorus (Astrophorida, Geodiidae)

    PubMed Central

    Graça, Ana Patrícia; Bondoso, Joana; Gaspar, Helena; Xavier, Joana R.; Monteiro, Maria Cândida; de la Cruz, Mercedes; Oves-Costales, Daniel; Vicente, Francisca; Lage, Olga Maria

    2013-01-01

    Heterotrophic bacteria associated with two specimens of the marine sponge Erylus discophorus were screened for their capacity to produce bioactive compounds against a panel of human pathogens (Staphylococcus aureus wild type and methicillin-resistant S. aureus (MRSA), Bacillus subtilis, Pseudomonas aeruginosa, Acinetobacter baumanii, Candida albicans and Aspergillus fumigatus), fish pathogen (Aliivibrio fischeri) and environmentally relevant bacteria (Vibrio harveyi). The sponges were collected in Berlengas Islands, Portugal. Of the 212 isolated heterotrophic bacteria belonging to Alpha- and Gammaproteobacteria, Actinobacteria and Firmicutes, 31% produced antimicrobial metabolites. Bioactivity was found against both Gram positive and Gram negative and clinically and environmentally relevant target microorganisms. Bioactivity was found mainly against B. subtilis and some bioactivity against S. aureus MRSA, V. harveyi and A. fisheri. No antifungal activity was detected. The three most bioactive genera were Pseudovibrio (47.0%), Vibrio (22.7%) and Bacillus (7.6%). Other less bioactive genera were Labrenzia, Acinetobacter, Microbulbifer, Pseudomonas, Gordonia, Microbacterium, Micrococcus and Mycobacterium, Paenibacillus and Staphylococcus. The search of polyketide I synthases (PKS-I) and nonribosomal peptide synthetases (NRPSs) genes in 59 of the bioactive bacteria suggested the presence of PKS-I in 12 strains, NRPS in 3 strains and both genes in 3 strains. Our results show the potential of the bacterial community associated with Erylus discophorus sponges as producers of bioactive compounds. PMID:24236081

  2. Bacterial capsular polysaccharide prevents the onset of asthma through T-cell activation.

    PubMed

    Johnson, Jenny L; Jones, Mark B; Cobb, Brian A

    2015-04-01

    Over the last four decades, increases in the incidence of immune-mediated diseases in the Western world have been linked to changes in microbial exposure. It is becoming increasingly clear that the normal microbiota in the gut can profoundly alter susceptibility to a wide range of diseases, such as asthma, in which immune homeostasis is disrupted, yet the mechanisms governing this microbial influence remains poorly defined. In this study, we show that gastrointestinal exposure to PSA, a capsular polysaccharide derived from the commensal bacterium Bacteroides fragilis, significantly limits susceptibility to the induction of experimental asthma. We report that direct treatment of mice with PSA generates protection from asthma, and this effect can be given to a naïve recipient by adoptive transfer of CD4(+) T cells from PSA-exposed mice. Remarkably, we found that these PSA-induced T cells are not canonical FoxP3(+) regulatory T cells, but that they potently inhibit both Th1 and Th2 models of asthma in an IL-10-dependent fashion. These findings reveal that bacterial polysaccharides link the microbiota with the peripheral immune system by activating CD4(+)Foxp3(-) T cells upon exposure in the gut, and they facilitate resistance to unnecessary inflammatory responses via the production of IL-10. PMID:25347992

  3. Whole‐cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills

    PubMed Central

    Zhang, Dayi; He, Yi; Wang, Yun; Wang, Hui; Wu, Lin; Aries, Eric; Huang, Wei E.

    2012-01-01

    Summary Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oil–water interface of 10–80 µm emulsified mineral and crude oil droplets. These properties make ADP1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. Acinetobacter baylyi bioreporter ADPWH_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. Bioreporter ADPWH_alk was able to detect a broad range of alkanes and alkenes with carbon chain length from C7 to C36. So far, ADPWH_alk is the only bioreporter that is able to detect alkane with carbon chain length greater than C18. This bioreporter responded to the alkanes in about 30 min and it was independent to the cell growth phase because of two point mutations in alkM promoter recognized by alkane regulatory protein ALKR. ADPWH_alk was applied to detect mineral oil, Brent, Chestnut and Sirri crude oils in water and seawater in the range 0.1–100 mg l−1, showing that the bioreporter oil detection was semi‐quantitative. This study demonstrates that ADPWH_alk is a rapid, sensitive and semi‐quantitative bioreporter that can be useful for environmental monitoring and assessment of oil spills in seawater and soils. PMID:21951420

  4. Antimicrobial activity of heterotrophic bacterial communities from the marine sponge Erylus discophorus (Astrophorida, Geodiidae).

    PubMed

    Graça, Ana Patrícia; Bondoso, Joana; Gaspar, Helena; Xavier, Joana R; Monteiro, Maria Cândida; de la Cruz, Mercedes; Oves-Costales, Daniel; Vicente, Francisca; Lage, Olga Maria

    2013-01-01

    Heterotrophic bacteria associated with two specimens of the marine sponge Erylus discophorus were screened for their capacity to produce bioactive compounds against a panel of human pathogens (Staphylococcus aureus wild type and methicillin-resistant S. aureus (MRSA), Bacillus subtilis, Pseudomonas aeruginosa, Acinetobacter baumanii, Candida albicans and Aspergillus fumigatus), fish pathogen (Aliivibrio fischeri) and environmentally relevant bacteria (Vibrio harveyi). The sponges were collected in Berlengas Islands, Portugal. Of the 212 isolated heterotrophic bacteria belonging to Alpha- and Gammaproteobacteria, Actinobacteria and Firmicutes, 31% produced antimicrobial metabolites. Bioactivity was found against both Gram positive and Gram negative and clinically and environmentally relevant target microorganisms. Bioactivity was found mainly against B. subtilis and some bioactivity against S. aureus MRSA, V. harveyi and A. fisheri. No antifungal activity was detected. The three most bioactive genera were Pseudovibrio (47.0%), Vibrio (22.7%) and Bacillus (7.6%). Other less bioactive genera were Labrenzia, Acinetobacter, Microbulbifer, Pseudomonas, Gordonia, Microbacterium, Micrococcus and Mycobacterium, Paenibacillus and Staphylococcus. The search of polyketide I synthases (PKS-I) and nonribosomal peptide synthetases (NRPSs) genes in 59 of the bioactive bacteria suggested the presence of PKS-I in 12 strains, NRPS in 3 strains and both genes in 3 strains. Our results show the potential of the bacterial community associated with Erylus discophorus sponges as producers of bioactive compounds. PMID:24236081

  5. Efficient production of active chicken avidin using a bacterial signal peptide in Escherichia coli

    PubMed Central

    2004-01-01

    Chicken avidin is a highly popular tool with countless applications in the life sciences. In the present study, an efficient method for producing avidin protein in the periplasmic space of Escherichia coli in the active form is described. Avidin was produced by replacing the native signal sequence of the protein with a bacterial OmpA secretion signal. The yield after a single 2-iminobiotin–agarose affinity purification step was approx. 10 mg/l of virtually pure avidin. Purified avidin had 3.7 free biotin-binding sites per tetramer and showed the same biotin-binding affinity and thermal stability as egg-white avidin. Avidin crystallized under various conditions, which will enable X-ray crystallographic studies. Avidin produced in E. coli lacks the carbohydrate chains of chicken avidin and the absence of glycosylation should decrease the non-specific binding that avidin exhibits towards many materials [Rosebrough and Hartley (1996) J. Nucl. Med. 37, 1380–1384]. The present method provides a feasible and inexpensive alternative for the production of recombinant avidin, avidin mutants and avidin fusion proteins for novel avidin–biotin technology applications. PMID:15324300

  6. The core-specific lysosomal alpha(1-6)-mannosidase activity depends on aspartamidohydrolase activity.

    PubMed Central

    Haeuw, J F; Grard, T; Alonso, C; Strecker, G; Michalski, J C

    1994-01-01

    The substrate specificity of the core-specific rat liver lysosomal alpha(1-6)-mannosidase was investigated using mannosylated oligosaccharides and glycoasparagines. Hydrolysis of Man(alpha 1-6) linkage hydrolysis was demonstrated to follow the action of endoglycosidases, namely aspartyl-N-acetyl-beta-D-glucosaminidase and endo-N-acetyl-beta-D-glucosaminidase. The results are discussed with respect to the nature of the carbohydrate materials stored in the tissues and excreted in the urine from patients suffering from aspartylglucosaminuria and fucosidosis. Images Figure 1 Figure 2 PMID:8110182

  7. A role for the perlecan protein core in the activation of the keratinocyte growth factor receptor.

    PubMed Central

    Ghiselli, G; Eichstetter, I; Iozzo, R V

    2001-01-01

    Perlecan, a widespread heparan sulphate (HS) proteoglycan, is directly involved in the storing of angiogenic growth factors, mostly members of the fibroblast growth factor (FGF) gene family. We have previously shown that antisense targeting of the perlecan gene causes a reduced growth and responsiveness to FGF7 [also known as keratinocyte growth factor (KGF)] in human cancer cells, and that the perlecan protein core interacts specifically with FGF7. In the present paper, we have investigated human colon carcinoma cells in which the perlecan gene was disrupted by targeted homologous recombination. After screening over 1000 clones, we obtained two clones heterozygous for the null mutation with no detectable perlecan, indicating that the other allele was non-functioning. The perlecan-deficient cells grew more slowly, did not respond to FGF7 with or without the addition of heparin, and were less tumorigenic than control cells. Paradoxically, the perlecan-deficient cells displayed increased FGF7 surface binding. However, the perlecan protein core was required for functional activation of the KGF receptor and downstream signalling. Because heparin could not substitute for perlecan, the HS chains are not critical for FGF7-mediated signalling in this cell system. These results provide the first genetic evidence that the perlecan protein core is a molecular entity implicated in FGF7 binding and activation of its receptor. PMID:11563979

  8. Defective disposal of immune complexes and polyclonal B cell activation persist long after exposure to bacterial lipopolysaccharide in mice

    SciTech Connect

    Granholm, N.A.; Cavallo, T. )

    1989-11-01

    Patients with systemic lupus erythematosus experience clinical exacerbation during superimposed bacterial infection. Previous studies in mice indicated that heightened immune phenomena during exposure to bacterial lipopolysaccharide (LPS) appear to be related, in part, to polyclonal B cell activation, to abnormal disposal of immune complexes (IC), and to increased localization of IC in tissues. To investigate whether such effects were reversible, we administered bacterial LPS to C57BL/6 mice for 5 weeks. Control mice received vehicle alone. We then discontinued LPS, and 6 weeks later LPS and control mice were challenged with a subsaturating dose of radiolabeled IC; the removal of IC from the circulation, their localization in the liver, spleen, and kidney were determined. In comparison to values in control mice, in mice previously exposed to LPS, serologic features of polyclonal B cell activation persisted; liver uptake of pathogenic IC (greater than Ag2Ab2) was normal, but removal of small size IC (less than or equal to Ag2Ab2) from the circulation was delayed; localization of IC in the kidneys was enhanced, and pathologic proteinuria developed. The effects of repeated exposure to bacterial LPS are partially reversible, but they last long after LPS is discontinued and may contribute to altered disposal of IC, enhanced organ localization of IC, and organ dysfunction.

  9. Surviving Chytridiomycosis: Differential Anti-Batrachochytrium dendrobatidis Activity in Bacterial Isolates from Three Lowland Species of Atelopus

    PubMed Central

    Flechas, Sandra V.; Sarmiento, Carolina; Cárdenas, Martha E.; Medina, Edgar M.; Restrepo, Silvia; Amézquita, Adolfo

    2012-01-01

    In the Neotropics, almost every species of the stream-dwelling harlequin toads (genus Atelopus) have experienced catastrophic declines. The persistence of lowland species of Atelopus could be explained by the lower growth rate of Batrachochytrium dendrobatidis (Bd) at temperatures above 25°C. We tested the complementary hypothesis that the toads' skin bacterial microbiota acts as a protective barrier against the pathogen, perhaps delaying or impeding the symptomatic phase of chytridiomycosis. We isolated 148 cultivable bacterial strains from three lowland Atelopus species and quantified the anti-Bd activity through antagonism assays. Twenty-six percent (38 strains representing 12 species) of the bacteria inhibited Bd growth and just two of them were shared among the toad species sampled in different localities. Interestingly, the strongest anti-Bd activity was measured in bacteria isolated from A. elegans, the only species that tested positive for the pathogen. The cutaneous bacterial microbiota is thus likely a fitness-enhancing trait that may (adaptation) or not (exaptation) have appeared because of natural selection mediated by chytridiomycosis. Our findings reveal bacterial strains for development of local probiotic treatments against chytridiomycosis and also shed light on the mechanisms behind the frog-bacteria-pathogen interaction. PMID:22970314

  10. Surviving chytridiomycosis: differential anti-Batrachochytrium dendrobatidis activity in bacterial isolates from three lowland species of Atelopus.

    PubMed

    Flechas, Sandra V; Sarmiento, Carolina; Cárdenas, Martha E; Medina, Edgar M; Restrepo, Silvia; Amézquita, Adolfo

    2012-01-01

    In the Neotropics, almost every species of the stream-dwelling harlequin toads (genus Atelopus) have experienced catastrophic declines. The persistence of lowland species of Atelopus could be explained by the lower growth rate of Batrachochytrium dendrobatidis (Bd) at temperatures above 25 °C. We tested the complementary hypothesis that the toads' skin bacterial microbiota acts as a protective barrier against the pathogen, perhaps delaying or impeding the symptomatic phase of chytridiomycosis. We isolated 148 cultivable bacterial strains from three lowland Atelopus species and quantified the anti-Bd activity through antagonism assays. Twenty-six percent (38 strains representing 12 species) of the bacteria inhibited Bd growth and just two of them were shared among the toad species sampled in different localities. Interestingly, the strongest anti-Bd activity was measured in bacteria isolated from A. elegans, the only species that tested positive for the pathogen. The cutaneous bacterial microbiota is thus likely a fitness-enhancing trait that may (adaptation) or not (exaptation) have appeared because of natural selection mediated by chytridiomycosis. Our findings reveal bacterial strains for development of local probiotic treatments against chytridiomycosis and also shed light on the mechanisms behind the frog-bacteria-pathogen interaction. PMID:22970314

  11. Correlation analysis of enzyme activities and deconstruction of ammonia-pretreated switchgrass by bacterial-fungal communities.

    PubMed

    Jain, Abhiney; Bediako, Sandra H; Henson, J Michael

    2016-10-01

    The mixed microbial communities that occur naturally on lignocellulosic feedstocks can provide feedstock-specific enzyme mixtures to saccharify lignocelluloses. Bacterial-fungal communities were enriched from switchgrass bales to deconstruct ammonia-pretreated switchgrass (DSG). Correlation analysis was carried out to elucidate the relationship between microbial decomposition of DSG by these communities, enzymatic activities produced and enzymatic saccharification of DSG using these enzyme mixtures. Results of the analysis showed that β-glucosidase and xylosidase activities limited the extent of microbial deconstruction and enzymatic saccharification of DSG. The results also underlined the importance of ligninase activity for the enzymatic saccharification of pretreated lignocellulosic feedstock. The bacterial-fungal communities developed in this research can be used to produce enzyme mixtures to deconstruct DSG, and the results from the correlation analysis can be used to optimize these enzyme mixtures for efficient saccharification of DSG to produce second-generation biofuels. PMID:27469088

  12. Abundance, activity, and diversity of archaeal and bacterial communities in both uncontaminated and highly copper-contaminated marine sediments.

    PubMed

    Besaury, Ludovic; Ghiglione, Jean-François; Quillet, Laurent

    2014-04-01

    We analyzed the impact of copper mine tailing discharges on benthic Archaea and Bacteria around the city of Chanaral in northern Chile. Quantitative PCR (Q-PCR) showed that the bacteria dominated the prokaryotic community at both sites, but only the bacteria showed a decrease in abundance in the copper-contaminated site. Q-PCR on reverse transcripts indicated a higher activity of both bacterial and archaeal communities in the contaminated site, suggesting an adaptation of the two communities to copper. This hypothesis was reinforced by the concomitant augmentation of the copper-resistant copA gene coding for a P-type ATP-ase pump in the contaminated site. The metabolically active bacterial community of the contaminated site was dominated by Gammaproteobacteria related to Ectothiorhodospiraceae and Chromatiaceae and by Alphaproteobacteria phylum related to Rhodobacteraceae. The metabolically active archaeal community was dominated by one lineage belonging to unclassified Euryarchaeota and to methanogenic Archaea. PMID:24072336

  13. Anti-inflammatory, anti-bacterial, and cytotoxic activity of fibrous clays.

    PubMed

    Cervini-Silva, Javiera; Nieto-Camacho, Antonio-; Ramírez-Apan, María Teresa; Gómez-Vidales, Virginia; Palacios, Eduardo; Montoya, Ascención; Ronquillo de Jesús, Elba

    2015-05-01

    Produced worldwide at 1.2m tons per year, fibrous clays are used in the production of pet litter, animal feed stuff to roof parcels, construction and rheological additives, and other applications needing to replace long-fiber length asbestos. To the authors' knowledge, however, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the anti-inflammatory, anti-bacterial, and cytotoxic activity by sepiolite (Vallecas, Spain) and palygorskite (Torrejon El Rubio, Spain). The anti-inflammatory activity was determined using the 12-O-tetradecanoylphorbol-13-acetate (TPA) and myeloperoxidase (MPO) methods. Histological cuts were obtained for quantifying leukocytes found in the epidermis. Palygorkite and sepiolite caused edema inhibition and migration of neutrophils ca. 68.64 and 45.54%, and 80 and 65%, respectively. Fibrous clays yielded high rates of infiltration, explained by cleavage of polysomes and exposure of silanol groups. Also, fibrous clays showed high inhibition of myeloperoxidase contents shortly after exposure, but decreased sharply afterwards. In contrast, tubular clays caused an increasing inhibition of myeloperoxidase with time. Thus, clay structure restricted the kinetics and mechanism of myeloperoxidase inhibition. Fibrous clays were screened in vitro against human cancer cell lines. Cytotoxicity was determined using the protein-binding dye sulforhodamine B (SRB). Exposing cancer human cells to sepiolite or palygorskite showed growth inhibition varying with cell line. This study shows that fibrous clays served as an effective anti-inflammatory, limited by chemical transfer and cellular-level signals responding exclusively to an early exposure to clay, and cell viability decreasing significantly only after exposure to high concentrations of sepiolite. PMID:25819359

  14. Layered Structure of Bacterial and Archaeal Communities and Their In Situ Activities in Anaerobic Granules▿ †

    PubMed Central

    Satoh, Hisashi; Miura, Yuki; Tsushima, Ikuo; Okabe, Satoshi

    2007-01-01

    The microbial community structure and spatial distribution of microorganisms and their in situ activities in anaerobic granules were investigated by 16S rRNA gene-based molecular techniques and microsensors for CH4, H2, pH, and the oxidation-reduction potential (ORP). The 16S rRNA gene-cloning analysis revealed that the clones related to the phyla Alphaproteobacteria (detection frequency, 51%), Firmicutes (20%), Chloroflexi (9%), and Betaproteobacteria (8%) dominated the bacterial clone library, and the predominant clones in the archaeal clone library were affiliated with Methanosaeta (73%). In situ hybridization with oligonucleotide probes at the phylum level revealed that these microorganisms were numerically abundant in the granule. A layered structure of microorganisms was found in the granule, where Chloroflexi and Betaproteobacteria were present in the outer shell of the granule, Firmicutes were found in the middle layer, and aceticlastic Archaea were restricted to the inner layer. Microsensor measurements for CH4, H2, pH, and ORP revealed that acid and H2 production occurred in the upper part of the granule, below which H2 consumption and CH4 production were detected. Direct comparison of the in situ activity distribution with the spatial distribution of the microorganisms implied that Chloroflexi contributed to the degradation of complex organic compounds in the outermost layer, H2 was produced mainly by Firmicutes in the middle layer, and Methanosaeta produced CH4 in the inner layer. We determined the effective diffusion coefficient for H2 in the anaerobic granules to be 2.66 × 10−5 cm2 s−1, which was 57% in water. PMID:17905889

  15. Oxygen Affects Gut Bacterial Colonization and Metabolic Activities in a Gnotobiotic Cockroach Model

    PubMed Central

    Tegtmeier, Dorothee; Thompson, Claire L.; Schauer, Christine

    2015-01-01

    The gut microbiota of termites and cockroaches represents complex metabolic networks of many diverse microbial populations. The distinct microenvironmental conditions within the gut and possible interactions among the microorganisms make it essential to investigate how far the metabolic properties of pure cultures reflect their activities in their natural environment. We established the cockroach Shelfordella lateralis as a gnotobiotic model and inoculated germfree nymphs with two bacterial strains isolated from the guts of conventional cockroaches. Fluorescence microscopy revealed that both strains specifically colonized the germfree hindgut. In diassociated cockroaches, the facultatively anaerobic strain EbSL (a new species of Enterobacteriaceae) always outnumbered the obligately anaerobic strain FuSL (a close relative of Fusobacterium varium), irrespective of the sequence of inoculation, which showed that precolonization by facultatively anaerobic bacteria does not necessarily favor colonization by obligate anaerobes. Comparison of the fermentation products of the cultures formed in vitro with those accumulated in situ indicated that the gut environment strongly affected the metabolic activities of both strains. The pure cultures formed the typical products of mixed-acid or butyrate fermentation, whereas the guts of gnotobiotic cockroaches accumulated mostly lactate and acetate. Similar shifts toward more-oxidized products were observed when the pure cultures were exposed to oxygen, which corroborated the strong effects of oxygen on the metabolic fluxes previously observed in termite guts. Oxygen microsensor profiles of the guts of germfree, gnotobiotic, and conventional cockroaches indicated that both gut tissue and microbiota contribute to oxygen consumption and suggest that the oxygen status influences the colonization success. PMID:26637604

  16. Effect of Grain Size on Bacterial Penetration, Reproduction, and Metabolic Activity in Porous Glass Bead Chambers

    PubMed Central

    Sharma, Pramod K.; McInerney, Michael J.

    1994-01-01

    We determined the effects of grain size and nutritional conditions on the penetration rate and metabolic activity of Escherichia coli strains in anaerobic, nutrient-saturated chambers packed with different sizes of glass beads (diameters, 116 to 767 μm) under static conditions. The chambers had nearly equal porosities (38%) but different calculated pore sizes (range, 10 to 65 μm). Motile strains always penetrated faster than nonmotile strains, and nutrient conditions that resulted in faster growth rates (fermentative conditions versus nitrate-respiring conditions) resulted in faster penetration rates for both motile and nonmotile strains for all of the bead sizes tested. The penetration rate of nonmotile strains increased linearly when bead size was increased, while the penetration rate of motile strains became independent of the bead size when beads having diameters of 398 μm or greater were used. The rate of H2 production and the final amount of H2 produced decreased when bead size was decreased. However, the final protein concentrations were similar in chambers packed with 116-, 192-, and 281-μm beads and were only slightly higher in chambers packed with 398- and 767-μm beads. Our data indicated that conditions that favored faster growth rates also resulted in faster penetration times and that the lower penetration rates observed in chambers packed with small beads were due to restriction of bacterial activity in the small pores. The large increases in the final amount of hydrogen produced without corresponding increases in the final amount of protein made indicated that metabolism became uncoupled from cell mass biosynthesis as bead size increased, suggesting that pore size influenced the efficiency of substrate utilization. PMID:16349250

  17. Inhibition of Bacterial Toxin Activity by the Nuclear Stain, DRAQ5™.

    PubMed

    Webb, Joshua N; Koufos, Evan; Brown, Angela C

    2016-08-01

    The repeats-in-toxin family of toxins includes proteins produced by Gram negative bacteria such as Escherichia coli (α-hemolysin), Bordetella pertussis (adenylate cyclase toxin), and Aggregatibacter actinomycetemcomitans (LtxA), which contribute to the pathogenesis of these organisms by killing host cells. In the case of LtxA produced by A. actinomycetemcomitans, white blood cells are targeted, allowing the bacteria to avoid clearance by the host immune system. In its association with target cells, LtxA binds to a receptor, lymphocyte function-associated antigen-1, as well as membrane lipids and cholesterol, before being internalized via a lysosomal-mediated pathway. The motivation for this project comes from our discovery that DRAQ5™, a membrane-permeable nuclear stain, prevents the internalization of LtxA in a Jurkat T cell line. We hypothesized that DRAQ5™, in crossing the plasma membrane, alters the properties of the membrane to inhibit LtxA internalization. To investigate how DRAQ5™ interacts with the lipid membrane to prevent LtxA internalization, we used studied DRAQ5™-mediated membrane changes in model membranes using a variety of techniques, including differential scanning calorimetry and fluorescence spectroscopy. Our results suggest that DRAQ5™ inhibits the activity of LtxA by decreasing the fluidity of the cellular lipid membrane, which decreases LtxA binding. These results present an interesting possible anti-virulence strategy; by altering bacterial toxin activity by modifying membrane fluidity, it may be possible to inhibit the pathogenicity of A. actinomycetemcomitans. PMID:27039399

  18. Oxygen Affects Gut Bacterial Colonization and Metabolic Activities in a Gnotobiotic Cockroach Model.

    PubMed

    Tegtmeier, Dorothee; Thompson, Claire L; Schauer, Christine; Brune, Andreas

    2016-02-01

    The gut microbiota of termites and cockroaches represents complex metabolic networks of many diverse microbial populations. The distinct microenvironmental conditions within the gut and possible interactions among the microorganisms make it essential to investigate how far the metabolic properties of pure cultures reflect their activities in their natural environment. We established the cockroach Shelfordella lateralis as a gnotobiotic model and inoculated germfree nymphs with two bacterial strains isolated from the guts of conventional cockroaches. Fluorescence microscopy revealed that both strains specifically colonized the germfree hindgut. In diassociated cockroaches, the facultatively anaerobic strain EbSL (a new species of Enterobacteriaceae) always outnumbered the obligately anaerobic strain FuSL (a close relative of Fusobacterium varium), irrespective of the sequence of inoculation, which showed that precolonization by facultatively anaerobic bacteria does not necessarily favor colonization by obligate anaerobes. Comparison of the fermentation products of the cultures formed in vitro with those accumulated in situ indicated that the gut environment strongly affected the metabolic activities of both strains. The pure cultures formed the typical products of mixed-acid or butyrate fermentation, whereas the guts of gnotobiotic cockroaches accumulated mostly lactate and acetate. Similar shifts toward more-oxidized products were observed when the pure cultures were exposed to oxygen, which corroborated the strong effects of oxygen on the metabolic fluxes previously observed in termite guts. Oxygen microsensor profiles of the guts of germfree, gnotobiotic, and conventional cockroaches indicated that both gut tissue and microbiota contribute to oxygen consumption and suggest that the oxygen status influences the colonization success. PMID:26637604

  19. Synthesis and anti-bacterial activity of some heterocyclic chalcone derivatives bearing thiofuran, furan, and quinoline moieties.

    PubMed

    Zheng, Chang-Ji; Jiang, Sheng-Ming; Chen, Zhen-Hua; Ye, Bai-Jun; Piao, Hu-Ri

    2011-10-01

    36 Novel heterocyclic chalcone derivatives were synthesized and tested for their anti-bacterial activity. Some compounds presented good anti-microbial activities against Gram-positive bacteria (including the multidrug-resistant clinical isolates). This class of compounds presented high potency against Streptococcus mutans, among which the derivatives F2 with an MIC of 2 µg/mL was as active as the standard drug (norfloxacin) and less active than oxacillin. All the compounds did not inhibit the growth of Gram-negative bacteria (Escherichia coli CCARM 1924 or Escherichia coli CCARM 1356) at 64 µg/mL. PMID:21887800

  20. Cometary cores with multiple structure from the oort cloud and the general scheme of origin of unusually active comets

    SciTech Connect

    Davydov, V.D.

    1986-03-01

    A newly conceived scheme is constructed which synthesizes consistent solutions to several principal problems concerning multiple-core comets: a power mechanism, a place and epoch of formation of the multiple core structure, the qualitative differences between current structure and younger structure, the origin of two types of cometary orbits, and a trigger mechanism for recent ignition of cometary activity of a multiple core. This scheme uses a new explanation of the ejection of dust (including icy dust) from various cometary cores as evidence that the material of multiple-core comets may be collisionally ablated at the expense of the comet-centered orbital energy of a multitude of massive boulders (see Kosm. Issled., No. 6 (1984)). Natural mechanisms are shown which preserve this important feature of multiple cores. The concept consists of the following elements: evolution of a system of satellites of the core toward a colli sionless structure; preservation of internal kinetic energy in the collisionless system over astro nomically lengthy time scales; tidal initiation of a collisional mechanism with the first revolution of the ancient multiple core in the zone of visibility. It is possible that such revoltions correspond to the existence of especially active comets in nearly parabolic orbits. Multiple structure in the core of active short-period comets might be descended from a nearly parabolic comet (if the theory holds on perturbational multistage transformation of near-parabolic orbits into contemporary short-period orbits).

  1. Impact of titanium dioxide nanoparticles on the bacterial communities of biological activated carbon filter intended for drinking water treatment.

    PubMed

    Zhiyuan, Liu; Shuili, Yu; Heedeung, Park; Qingbin, Yuan; Guicai, Liu; Qi, Li

    2016-08-01

    Titanium dioxide nanoparticles (TiO2 NPs) are inevitably present in the aquatic environment owing to their increasing production and use. However, knowledge of the potential effects of TiO2 NPs on the treatment of drinking water is scarce. Herein, the effects of two types of anatase TiO2 NPs (TP1, 25 nm; TP2, 100 nm) on the bacterial community in a biological activated carbon (BAC) filter were investigated via quantitative polymerase chain reaction (Q-PCR) analysis, ATP quantification, and 454 pyrosequencing analysis. Both TP1 and TP2 significantly inhibited the bacterial ATP level (p < 0.01) and induced a decrease in the abundance of bacterial 16S rDNA gene copies at doses of 0.1 and 100 mg L(-1). Simultaneously, the diversity and evenness of the bacterial communities were considerably reduced. The relative abundances of bacteria annotated to OTUs from Nitrospira class and Betaproteobacteria class decreased upon TiO2 NP treatment, whereas those of Bacilli class and Gammaproteobacteria class increased. TiO2 NP size showed a greater effect on the bacterial composition than did the dose based on Bray-Curtis distances. These findings identified negative effects of TiO2 NPs on the bacterial community in the BAC filter. Given the fact that BAC filters are used widely in drinking water treatment plants, these results suggested a potential threat by TiO2 NP to drinking water treatment system. PMID:27126871

  2. K+ efflux is the Common Trigger of NLRP3 inflammasome Activation by Bacterial Toxins and Particulate Matter

    PubMed Central

    Muñoz-Planillo, Raúl; Kuffa, Peter; Martínez-Colón, Giovanny; Smith, Brenna L.; Rajendiran, Thekkelnaycke M.; Núñez, Gabriel

    2013-01-01

    Summary The NLRP3 inflammasome is an important component of the innate immune system. However, its mechanism of activation remains largely unknown. We show that NLRP3 activators including bacterial pore-forming toxins, nigericin, ATP and particulate matter caused mitochondrial perturbation or the opening of a large membrane pore; but this was not required for NLRP3 activation. Furthermore, reactive oxygen species generation or a change in cell volume was not necessary for NLRP3 activation. Instead, the only common activity induced by all NLRP3 agonists was the permeation of the cell membrane to K+ and Na+. Notably, reduction of the intracellular K+ concentration was sufficient to activate NLRP3 whereas an increase in intracellular Na+ modulated, but was not strictly required for inflammasome activation. These results provide a unifying model for the activation of the NLRP3 inflammasome in which a drop in cytosolic K+ is the common step that is necessary and sufficient for caspase-1 activation. PMID:23809161

  3. Heterotrophic bacterial production and extracellular enzymatic activity in sinking particulate matter in the western North Pacific Ocean

    PubMed Central

    Yamada, Namiha; Fukuda, Hideki; Ogawa, Hiroshi; Saito, Hiroaki; Suzumura, Masahiro

    2012-01-01

    Heterotrophic activities on sinking particulate matter (SPM) play an important role in SPM fluxes in the ocean. To demonstrate regional differences in heterotrophic activities on SPM, we measured heterotrophic bacterial production (HBP) in seawater (HBPSW) and SPM (HBPSPM) as well as potential extracellular enzyme activity (EEA) in SPM on a transect along 155°E in the western North Pacific Ocean in the subarctic (44°N), the Kuroshio Extension area (35°N), and the subtropical gyre (20°N). Depth-integrated HBPSW from the surface to 500 m was comparable between the locations, whereas HBPSPM at 44°N was substantially lower than at the other sites. We found the highest particulate organic carbon (POC) export flux and export efficiency to bathypelagic depths, and the lowest water temperatures, at 44°N. We found significant correlations between leucine aminopeptidase (LAPase) activity, β-glucosidase (BGase) activity, POC flux and particulate organic nitrogen flux. LAPase activity was two orders of magnitude higher than BGase activity, with a BGase:LAPase activity ratio of 0.027. There were no significant correlations between HBP and EEA in SPM except for lipase, and lipase activity was significantly correlated with temperature. We propose that hydrographic conditions are an important factor controlling heterotrophic bacterial activity and export efficiency of organic carbon to the deep ocean, as are the sources and abundance of SPM produced in the euphotic zone via primary production. PMID:23109933

  4. Determining heating timescales in solar active region cores from AIA/SDO Fe XVIII images

    SciTech Connect

    Ugarte-Urra, Ignacio; Warren, Harry P.

    2014-03-01

    We present a study of the frequency of transient brightenings in the core of solar active regions as observed in the Fe XVIII line component of AIA/SDO 94 Å filter images. The Fe XVIII emission is isolated using an empirical correction to remove the contribution of 'warm' emission to this channel. Comparing with simultaneous observations from EIS/Hinode, we find that the variability observed in Fe XVIII is strongly correlated with the emission from lines formed at similar temperatures. We examine the evolution of loops in the cores of active regions at various stages of evolution. Using a newly developed event detection algorithm, we characterize the distribution of event frequency, duration, and magnitude in these active regions. These distributions are similar for regions of similar age and show a consistent pattern as the regions age. This suggests that these characteristics are important constraints for models of solar active regions. We find that the typical frequency of the intensity fluctuations is about 1400 s for any given line of sight, i.e., about two to three events per hour. Using the EBTEL 0D hydrodynamic model, however, we show that this only sets a lower limit on the heating frequency along that line of sight.

  5. Early Human Activity (pre-332 BC) in Alexandria, Egypt: New findings in Eastern Harbor Cores

    NASA Astrophysics Data System (ADS)

    Stanley, J.; Landau, E. A.

    2005-12-01

    Historians have long postulated that a settlement called Rhakotis was present on Egypt's Mediterranean coast in the area subsequently occupied by the city of Alexandria. To date, however, the precise position of that site has not been located in the immediate area of the city founded by Alexander the Great. Also undefined are the earliest phases of occupation that pre-date Alexandria on Pharos Island and in the harbour area. A geoarchaeological project emphasizing sediment cores in Alexandria's Eastern Harbour now provides evidence of human occupation adjacent to these settings prior to establishment of Greece's great port in 332 BC. A radiocarbon-dated stratigraphic unit, defined as Middle Sand (III) and older than the 4th century BC, includes locally produced ceramics, along with rock fragments of non-local origin, and increased content of sand-sized heavy mineral and organic matter. Together, these date at least to Egypt's Late Dynastic Period (712-332 BC). Moreover, the geographic positions of core sites containing these markers indicate that early habitation occurred both at Pharos Island and on the mainland where the future Alexandria would be built. New findings in cores recovered in this marine environment are adding to knowledge of both natural processes and effects of human activity in early Alexandria.

  6. Core-Shell Composite Hydrogels for Controlled Nanocrystal Formation and Release of Hydrophobic Active Pharmaceutical Ingredients.

    PubMed

    Badruddoza, Abu Zayed Md; Godfrin, P Douglas; Myerson, Allan S; Trout, Bernhardt L; Doyle, Patrick S

    2016-08-01

    Although roughly 40% of pharmaceuticals being developed are poorly water soluble, this class of drugs lacks a formulation strategy capable of producing high loads, fast dissolution kinetics, and low energy input. In this work, a novel bottom-up approach is developed for producing and formulating nanocrystals of poorly water-soluble active pharmaceutical ingredients (APIs) using core-shell composite hydrogel beads. Organic phase nanoemulsion droplets stabilized by polyvinyl alcohol (PVA) and containing a model hydrophobic API (fenofibrate) are embedded in the alginate hydrogel matrix and subsequently act as crystallization reactors. Controlled evaporation of this composite material produces core-shell structured alginate-PVA hydrogels with drug nanocrystals (500-650 nm) embedded within the core. Adjustable loading of API nanocrystals up to 83% by weight is achieved with dissolution (of 80% of the drug) occurring in as little as 30 min. A quantitative model is also developed and experimentally validated that the drug release patterns of the fenofibrate nanocrystals can be modulated by controlling the thickness of the PVA shell and drug loading. Thus, these composite materials offer a "designer" drug delivery system. Overall, our approach enables a novel means of simultaneous controlled crystallization and formulation of hydrophobic drugs that circumvents energy intensive top-down processes in traditional manufacturing. PMID:27249402

  7. Bacterial Population Dynamics in a Laboratory Activated Sludge Reactor Monitored by Pyrosequencing of 16S rRNA

    PubMed Central

    Satoh, Hiroyasu; Oshima, Kenshiro; Suda, Wataru; Ranasinghe, Purnika; Li, Ning; Gunawardana, Egodaha Gedara Wasana; Hattori, Masahira; Mino, Takashi

    2013-01-01

    The microbial population in a laboratory activated sludge reactor was monitored for 245 d at 75 time points by pyrosequencing of 16S rRNA. Synthetic wastewater was used as the influent, and the reactor was operated under the same conditions throughout the experiment. The behaviors of different bacterial operational taxonomic units (OTUs) were observed. Multiple OTUs showed periodic propagation and recession. One of the OTUs showed sharp recession, which suggests that cells in the OTU were selectively killed. The behaviors of different phylogenetic lineages of Candidatus ‘Accumulibacter phosphatis’ were also visualized. It was clearly demonstrated that pyrosequencing with barcoded primers is a very effective tool to clarify the dynamics of the bacterial population in activated sludge. PMID:23100021

  8. Optimization of physicochemical properties and safety profile of novel bacterial topoisomerase type II inhibitors (NBTIs) with activity against Pseudomonas aeruginosa.

    PubMed

    Reck, Folkert; Ehmann, David E; Dougherty, Thomas J; Newman, Joseph V; Hopkins, Sussie; Stone, Gregory; Agrawal, Nikunj; Ciaccio, Paul; McNulty, John; Barthlow, Herbert; O'Donnell, Jennifer; Goteti, Kosalaram; Breen, John; Comita-Prevoir, Janelle; Cornebise, Mark; Cronin, Mark; Eyermann, Charles J; Geng, Bolin; Carr, Greg R; Pandarinathan, Lakshmipathi; Tang, Xuejun; Cottone, Andrew; Zhao, Liang; Bezdenejnih-Snyder, Natascha

    2014-10-01

    Type II bacterial topoisomerases are well validated targets for antimicrobial chemotherapy. Novel bacterial type II topoisomerase inhibitors (NBTIs) of these targets are of interest for the development of new antibacterial agents that are not impacted by target-mediated cross-resistance with fluoroquinolones. We now disclose the optimization of a class of NBTIs towards Gram-negative pathogens, especially against drug-resistant Pseudomonas aeruginosa. Physicochemical properties (pKa and logD) were optimized for activity against P. aeruginosa and for reduced inhibition of the hERG channel. The optimized analogs 9g and 9i displayed potent antibacterial activity against P. aeruginosa, and a significantly improved hERG profile over previously reported analogs. Compound 9g showed an improved QT profile in in vivo models and lower clearance in rat over earlier compounds. The compounds show promise for the development of new antimicrobial agents against drug-resistant Pseudomonas aeruginosa. PMID:25155913

  9. Bacterial chemoreceptor dynamics correlate with activity state and are coupled over long distances

    PubMed Central

    Samanta, Dipanjan; Borbat, Peter P.; Dzikovski, Boris; Freed, Jack H.; Crane, Brian R.

    2015-01-01

    Dynamics are hypothesized to play an important role in the transmission of signals across membranes by receptors. Bacterial chemoreceptors are long helical proteins that consist of a periplasmic ligand-binding domain; a transmembrane region; a cytoplasmic HAMP (histidine kinase, adenylyl cyclases, methyl-accepting chemotaxis proteins, and phosphatases) domain; and a kinase-control module (KCM). The KCM is further composed of adaptation, hinge, and protein interaction regions (PIRs), the latter of which binds the histidine kinase CheA and adaptor CheW. Fusions of the Escherichia coli aspartate receptor KCM to HAMP domains of defined structure (H1-Tar vs. H1-2-Tar) give opposite responses in phosphotransfer and cellular assays, despite similar binding to CheA and CheW. Pulsed dipolar ESR spectroscopy (PDS) of these isolated on and off dimeric effectors reveals that, in the kinase-on state, the HAMP is more conformationally destabilized compared with the PIR, whereas in the kinase-off state, the HAMP is more compact, and the PIR samples a greater breadth of conformations. On and off HAMP states produce different conformational effects at the KCM junction, but these differences decrease through the adaptation region and into the hinge only to return with the inverted relationship in the PIR. Continuous wave–ESR of the spin-labeled proteins confirms that broader PDS distance distributions correlate with increased rates of dynamics. Conformational breadth in the adaptation region changes with charge alterations caused by modification enzymes. Activating modifications broaden the HAMP conformational ensemble but correspondingly, compact the PIR. Thus, chemoreceptors behave as coupled units, in which dynamics in regions proximal and distal to the membrane change coherently but with opposite sign. PMID:25675479

  10. Gut Commensal E. coli Proteins Activate Host Satiety Pathways following Nutrient-Induced Bacterial Growth.

    PubMed

    Breton, Jonathan; Tennoune, Naouel; Lucas, Nicolas; Francois, Marie; Legrand, Romain; Jacquemot, Justine; Goichon, Alexis; Guérin, Charlène; Peltier, Johann; Pestel-Caron, Martine; Chan, Philippe; Vaudry, David; do Rego, Jean-Claude; Liénard, Fabienne; Pénicaud, Luc; Fioramonti, Xavier; Ebenezer, Ivor S; Hökfelt, Tomas; Déchelotte, Pierre; Fetissov, Sergueï O

    2016-02-01

    The composition of gut microbiota has been associated with host metabolic phenotypes, but it is not known if gut bacteria may influence host appetite. Here we show that regular nutrient provision stabilizes exponential growth of E. coli, with the stationary phase occurring 20 min after nutrient supply accompanied by bacterial proteome changes, suggesting involvement of bacterial proteins in host satiety. Indeed, intestinal infusions of E. coli stationary phase proteins increased plasma PYY and their intraperitoneal injections suppressed acutely food intake and activated c-Fos in hypothalamic POMC neurons, while their repeated administrations reduced meal size. ClpB, a bacterial protein mimetic of α-MSH, was upregulated in the E. coli stationary phase, was detected in plasma proportional to ClpB DNA in feces, and stimulated firing rate of hypothalamic POMC neurons. Thus, these data show that bacterial proteins produced after nutrient-induced E. coli growth may signal meal termination. Furthermore, continuous exposure to E. coli proteins may influence long-term meal pattern. PMID:26621107

  11. Measuring bacterial activity and community composition at high hydrostatic pressure using a novel experimental approach: a pilot study.

    PubMed

    Wannicke, Nicola; Frindte, Katharina; Gust, Giselher; Liskow, Iris; Wacker, Alexander; Meyer, Andreas; Grossart, Hans-Peter

    2015-05-01

    In this pilot study, we describe a high-pressure incubation system allowing multiple subsampling of a pressurized culture without decompression. The system was tested using one piezophilic (Photobacterium profundum), one piezotolerant (Colwellia maris) bacterial strain and a decompressed sample from the Mediterranean deep sea (3044 m) determining bacterial community composition, protein production (BPP) and cell multiplication rates (BCM) up to 27 MPa. The results showed elevation of BPP at high pressure was by a factor of 1.5 ± 1.4 and 3.9 ± 2.3 for P. profundum and C. maris, respectively, compared to ambient-pressure treatments and by a factor of 6.9 ± 3.8 fold in the field samples. In P. profundum and C. maris, BCM at high pressure was elevated (3.1 ± 1.5 and 2.9 ± 1.7 fold, respectively) compared to the ambient-pressure treatments. After 3 days of incubation at 27 MPa, the natural bacterial deep-sea community was dominated by one phylum of the genus Exiguobacterium, indicating the rapid selection of piezotolerant bacteria. In future studies, our novel incubation system could be part of an isopiestic pressure chain, allowing more accurate measurement of bacterial activity rates which is important both for modeling and for predicting the efficiency of the oceanic carbon pump. PMID:25873457

  12. Transcriptional Activation of c3 and hsp70 as Part of the Immune Response of Acropora millepora to Bacterial Challenges

    PubMed Central

    Brown, Tanya; Bourne, David; Rodriguez-Lanetty, Mauricio

    2013-01-01

    The impact of disease outbreaks on coral physiology represents an increasing concern for the fitness and resilience of reef ecosystems. Predicting the tolerance of corals to disease relies on an understanding of the coral immune response to pathogenic interactions. This study explored the transcriptional response of two putative immune genes (c3 and c-type lectin) and one stress response gene (hsp70) in the reef building coral, Acropora millepora challenged for 48 hours with bacterial strains, Vibrio coralliilyticus and Alteromonas sp. at concentrations of 106 cells ml-1. Coral fragments challenged with V. coralliilyticus appeared healthy while fragments challenged with Alteromonas sp. showed signs of tissue lesions after 48 hr. Coral-associated bacterial community profiles assessed using denaturing gradient gel electrophoresis changed after challenge by both bacterial strains with the Alteromonas sp. treatment demonstrating the greatest community shift. Transcriptional profiles of c3 and hsp70 increased at 24 hours and correlated with disease signs in the Alteromonas sp. treatment. The expression of hsp70 also showed a significant increase in V. coralliilyticus inoculated corals at 24 h suggesting that even in the absence of disease signs, the microbial inoculum activated a stress response in the coral. C-type lectin did not show a response to any of the bacterial treatments. Increase in gene expression of c3 and hsp70 in corals showing signs of disease indicates their potential involvement in immune and stress response to microbial challenges. PMID:23861754

  13. Transcriptional activation of c3 and hsp70 as part of the immune response of Acropora millepora to bacterial challenges.

    PubMed

    Brown, Tanya; Bourne, David; Rodriguez-Lanetty, Mauricio

    2013-01-01

    The impact of disease outbreaks on coral physiology represents an increasing concern for the fitness and resilience of reef ecosystems. Predicting the tolerance of corals to disease relies on an understanding of the coral immune response to pathogenic interactions. This study explored the transcriptional response of two putative immune genes (c3 and c-type lectin) and one stress response gene (hsp70) in the reef building coral, Acropora millepora challenged for 48 hours with bacterial strains, Vibrio coralliilyticus and Alteromonas sp. at concentrations of 10(6) cells ml(-1). Coral fragments challenged with V. coralliilyticus appeared healthy while fragments challenged with Alteromonas sp. showed signs of tissue lesions after 48 hr. Coral-associated bacterial community profiles assessed using denaturing gradient gel electrophoresis changed after challenge by both bacterial strains with the Alteromonas sp. treatment demonstrating the greatest community shift. Transcriptional profiles of c3 and hsp70 increased at 24 hours and correlated with disease signs in the Alteromonas sp. treatment. The expression of hsp70 also showed a significant increase in V. coralliilyticus inoculated corals at 24 h suggesting that even in the absence of disease signs, the microbial inoculum activated a stress response in the coral. C-type lectin did not show a response to any of the bacterial treatments. Increase in gene expression of c3 and hsp70 in corals showing signs of disease indicates their potential involvement in immune and stress response to microbial challenges. PMID:23861754

  14. Topoisomerase I activity associated with human immunodeficiency virus (HIV) particles and equine infectious anemia virus core.

    PubMed Central

    Priel, E; Showalter, S D; Roberts, M; Oroszlan, S; Segal, S; Aboud, M; Blair, D G

    1990-01-01

    In the present study, we found a topoisomerase I (topo I) activity in two strains of human immunodeficiency virus type 1 (HIV-1) and equine infectious anemia virus (EIAV) particles. The topo I activity was located in the EIAV cores and differed from the cellular topo I in its ionic requirements and response to ATP, indicating that these were two distinct forms of this enzyme. Topo I activity was removed from the viral lysates and viral cores by anti-topo I antiserum. The only protein recognized by this antiserum was an 11.5 kd protein in HIV lysate and 11 kd in EIAV lysate. We showed that the 11 kd protein recognized by the anti-topo I antiserum is the EIAV p11 nucleocapsid protein. Furthermore, purified topo I protein blocked the binding of the antibodies to the p11 protein and vice versa, purified p11 protein blocked the binding of these antibodies to the cellular topo I. These results suggest that the EIAV p11 nucleocapsid protein and the cellular topo I share similar epitopes. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:2174357

  15. Palladium-platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction.

    PubMed

    Wang, Xue; Choi, Sang-Il; Roling, Luke T; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A; Mavrikakis, Manos; Xia, Younan

    2015-01-01

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. These results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability. PMID:26133469

  16. Palladium–platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    DOE PAGESBeta

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A.; et al

    2015-07-02

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can bemore » attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. Ultimately, these results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.« less

  17. Synthesis of azobenzenealkylmaleimide probes to photocontrol the enzyme activity of a bacterial histone deacetylase-like amidohydrolase.

    PubMed

    Horstmann, Benjamin; Korbus, Michael; Friedmann, Tatjana; Wolff, Christiane; Thiele, Christina Marie; Meyer-Almes, Franz-Josef

    2014-12-01

    A series of azobenzenealkylmaleimides (AMDs) with different spacer length was synthesized and coupled via Michael-Addition to a specific mutant of a bacterial histone deacetylase-like amidohydrolase (HDAH). Michaelis-Menten parameters (Vmax and Km) were employed to characterize the effect of both, the spacer length and the configuration (cis vs. trans) of the attached azobenzene moiety, on the HDAH enzyme activity. The photoswitch behavior of the AMD/enzyme conjugate activity was clearly influenced by the AMD spacer length. This study highlights the importance of steric rearrangement of the photoswitch with respect to the active site and describes a strategy to optimize the photocontrol of HDAH. PMID:25462992

  18. Graphene oxide exhibits broad-spectrum antimicrobial activity against bacterial phytopathogens and fungal conidia by intertwining and membrane perturbation

    NASA Astrophysics Data System (ADS)

    Chen, Juanni; Peng, Hui; Wang, Xiuping; Shao, Feng; Yuan, Zhaodong; Han, Heyou

    2014-01-01

    To understand the interaction mechanism between graphene oxide (GO) and typical phytopathogens, a particular investigation was conducted about the antimicrobial activity of GO against two bacterial pathogens (P. syringae and X. campestris pv. undulosa) and two fungal pathogens (F. graminearum and F. oxysporum). The results showed that GO had a powerful effect on the reproduction of all four pathogens (killed nearly 90% of the bacteria and repressed 80% macroconidia germination along with partial cell swelling and lysis at 500 μg mL-1). A mutual mechanism is proposed in this work that GO intertwinds the bacteria and fungal spores with a wide range of aggregated graphene oxide sheets, resulting in the local perturbation of their cell membrane and inducing the decrease of the bacterial membrane potential and the leakage of electrolytes of fungal spores. It is likely that GO interacts with the pathogens by mechanically wrapping and locally damaging the cell membrane and finally causing cell lysis, which may be one of the major toxicity actions of GO against phytopathogens. The antibacterial mode proposed in this study suggests that the GO may possess antibacterial activity against more multi-resistant bacterial and fungal phytopathogens, and provides useful information about the application of GO in resisting crop diseases.To understand the interaction mechanism between graphene oxide (GO) and typical phytopathogens, a particular investigation was conducted about the antimicrobial activity of GO against two bacterial pathogens (P. syringae and X. campestris pv. undulosa) and two fungal pathogens (F. graminearum and F. oxysporum). The results showed that GO had a powerful effect on the reproduction of all four pathogens (killed nearly 90% of the bacteria and repressed 80% macroconidia germination along with partial cell swelling and lysis at 500 μg mL-1). A mutual mechanism is proposed in this work that GO intertwinds the bacteria and fungal spores with a wide range

  19. Comparison of denitrification activity measurements in groundwater using cores and natural-gradient tracer tests

    USGS Publications Warehouse

    Smith, R.L.; Garabedian, S.P.; Brooks, M.H.

    1996-01-01

    The transport of many solutes in groundwater is dependent upon the relative rates of physical flow and microbial metabolism. Quantifying rates of microbial processes under subsurface conditions is difficult and is most commonly approximated using laboratory studies with aquifer materials. In this study, we measured in situ rates of denitrification in a nitrate- contaminated aquifer using small-scale, natural-gradient tracer tests and compared the results with rates obtained from laboratory incubations with aquifer core material. Activity was measured using the acetylene block technique. For the tracer tests, co-injection of acetylene and bromide into the aquifer produced a 30 ??M increase in nitrous oxide after 10 m of transport (23-30 days). An advection-dispersion transport model was modified to include an acetylene-dependent nitrous oxide production term and used to simulate the tracer breakthrough curves. The model required a 4-day lag period and a relatively low sensitivity to acetylene to match the narrow nitrous oxide breakthrough curves. Estimates of in situ denitrification rates were 0.60 and 1.51 nmol of N2O produced cm-3 aquifer day-1 for two successive tests. Aquifer core material collected from the tracer test site and incubated as mixed slurries in flasks and as intact cores yielded rates that were 1.2-26 times higher than the tracer test rate estimates. Results with the coring-dependent techniques were variable and subject to the small- scale heterogeneity within the aquifer, while the tracer tests integrated the heterogeneity along a flow path, giving a rate estimate that is more applicable to transport at the scale of the aquifer.

  20. Optimal design of hollow core-shell structural active materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Jiang, Wenjuan; Li, Tingting; Ma, Zengsheng; Lin, Jianguo; Lu, Chunsheng

    To mitigate mechanical and chemical degradation of active materials, hollow core-shell structures have been applied in lithium ion batteries. Without embedding of lithium ions, the rigid coating shell can constrain the inward volume deformation. In this paper, optimal conditions for the full use of inner hollow space are identified in terms of the critical ratio of shell thickness and inner size and the state of charge. It is shown that the critical ratios are 0.10 and 0.15 for Si particle and tube (0.12 and 0.18 for Sn particle and tube), and above which there is lack of space for further lithiation.

  1. Discovery of fused tricyclic core containing HCV NS5A inhibitors with pan-genotype activity.

    PubMed

    Yu, Wensheng; Coburn, Craig A; Yang, De-Yi; Meinke, Peter T; Wong, Michael; Rosenblum, Stuart B; Chen, Kevin X; Njoroge, George F; Chen, Lei; Dwyer, Michael P; Jiang, Yueheng; Nair, Anilkumar G; Selyutin, Oleg; Tong, Ling; Zeng, Qingbei; Zhong, Bin; Ji, Tao; Hu, Bin; Agrawal, Sony; Xia, Ellen; Zhai, Ying; Liu, Rong; Kong, Rong; Ingravallo, Paul; Asante-Appiah, Ernest; Nomeir, Amin; Fells, James; Kozlowski, Joseph A

    2016-07-01

    HCV NS5A inhibitors have demonstrated impressive in vitro potency profiles in HCV replicon assays and robust HCV RNA titer reduction in the clinic making them attractive components for inclusion in an all oral fixed dose combination regimen for the treatment of HCV infection. Herein, we describe research efforts that led to the discovery of a series of fused tricyclic core containing HCV NS5A inhibitors such as 24, 39, 40, 43, and 44 which have pan-genotype activity and are orally bioavailable in the rat. PMID:27180013

  2. AWM 4: a sharp look at the core of a poor cluster stirred by AGN activity

    NASA Astrophysics Data System (ADS)

    Vrtilek, Jan

    2007-09-01

    The central regions of galaxy clusters, frequently occupied by massive elliptical galaxies with strong radio sources interacting with dense, X-ray emitting gas, are among the most interesting and physically active regions in the Universe. We here propose a deep observation of AWM 4, a poor cluster of relaxed appearance without a cooling core but with strong evidence of AGN-driven heating and gas mixing. In this unusual object we will examine the interaction between cluster gas and radio source at high resolution, measure the properties of the gas and constrain the energy budget of the radio source, and clarify the nature of the observed abundance irregularities.

  3. Risperidone alters food intake, core body temperature, and locomotor activity in mice

    PubMed Central

    Cope, Mark B.; Li, Xingsheng; Jumbo-Lucioni, Patricia; DiCostanzo, Catherine A.; Jamison, Wendi G.; Kesterson, Robert A.; Allison, David B.; Nagy, Tim R.

    2009-01-01

    Risperidone induces significant weight gain in female mice; however, the underlying mechanisms related to this effect are unknown. We investigated the effects of risperidone on locomotor activity, core body temperature, and uncoupling protein (UCP) and hypothalamic orexin mRNA expression. Female C57BL/6J mice were acclimated to individual housing and randomly assigned to either risperidone (4 mg/kg BW*day) or placebo (PLA). Activity and body temperature were measured over 48-hour periods twice a week for 3 weeks. Food intake and body weights were measured weekly. UCP1 (BAT), UCP3 (gastrocnemius), and orexin (hypothalamus) mRNA expressions were measured using RT-PCR. Risperidone-treated mice consumed more food (p=0.050) and gained more weight (p=0.0001) than PLA-treated mice after 3 weeks. During the initial 2-days of treatment, there was an acute effect of treatment on activity (p=0.046), but not body temperature (p=0.290). During 3 weeks of treatment, average core body temperatures were higher in risperidone-treated mice compared to controls during the light phase (p=0.0001), and tended to be higher during the dark phase (p=0.057). Risperidone-treated mice exhibited lower activity levels than controls during the dark phase (p=0.006); there were no differences in activity during the light phase (p=0.47). UCP1 (p<0.01) and UCP3 (p<0.05) mRNA expressions were greater in risperidone-treated mice compared to controls, whereas, orexin mRNA expression was lower in risperidone-treated mice (p<0.01). These results suggest that risperidone-induced weight gain in mice is a consequence of increased energy intake and reduced activity, while the elevation in body temperature may be a result of thermogenic effect of food intake and elevated UCP1, UCP3, and a reduced hypothalamic orexin expression. PMID:19084548

  4. Impacts of Multiwalled Carbon Nanotubes on Nutrient Removal from Wastewater and Bacterial Community Structure in Activated Sludge

    PubMed Central

    Hai, Reti; Wang, Yulin; Wang, Xiaohui; Du, Zhize; Li, Yuan

    2014-01-01

    Background The increasing use of multiwalled carbon nanotubes (MWCNTs) will inevitably lead to the exposure of wastewater treatment facilities. However, knowledge of the impacts of MWCNTs on wastewater nutrient removal and bacterial community structure in the activated sludge process is sparse. Aims To investigate the effects of MWCNTs on wastewater nutrient removal, and bacterial community structure in activated sludge. Methods Three triplicate sequencing batch reactors (SBR) were exposed to wastewater which contained 0, 1, and 20 mg/L MWCNTs. MiSeq sequencing was used to investigate the bacterial community structures in activated sludge samples which were exposed to different concentrations of MWCNTs. Results Exposure to 1 and 20 mg/L MWCNTs had no acute (1 day) impact on nutrient removal from wastewater. After long-term (180 days) exposure to 1 mg/L MWCNTs, the average total nitrogen (TN) removal efficiency was not significantly affected. TN removal efficiency decreased from 84.0% to 71.9% after long-term effects of 20 mg/L MWCNTs. After long-term exposure to 1 and 20 mg/L MWCNTs, the total phosphorus removal efficiencies decreased from 96.8% to 52.3% and from 98.2% to 34.0% respectively. Further study revealed that long-term exposure to 20 mg/L MWCNTs inhibited activities of ammonia monooxygenase and nitrite oxidoreductase. Long-term exposure to 1 and 20 mg/L MWCNTs both inhibited activities of exopolyphosphatase and polyphosphate kinase. MiSeq sequencing data indicated that 20 mg/L MWCNTs significantly decreased the diversity of bacterial community in activated sludge. Long-term exposure to 1 and 20 mg/L MWCNTs differentially decreased the abundance of nitrifying bacteria, especially ammonia-oxidizing bacteria. The abundance of PAOs was decreased after long-term exposure to 20 mg/L MWCNTs. The abundance of glycogen accumulating organisms (GAOs) was increased after long-term exposure to 1 mg/L MWCNTs. Conclusion MWCNTs have adverse effects on biological

  5. Evidence from a carbohydrate incorporation assay for direct activation of bone marrow myelopoietic precursor cells by bacterial cell wall constitutents.

    PubMed Central

    Monner, D A; Gmeiner, J; Mühlradt, P F

    1981-01-01

    The stimulation of incorporation of [3H]galactose into membrane glycoconjugates, measured in a precipitation test, was used as a criterion for activation of bone marrow cells. In this assay, purified bacterial lipopolysaccharide, lipoprotein, and murein monomer and dimer fragments all activated rat bone marrow cells in vitro. The response was dose dependent, followed a defined time course, and was not serum dependent. O-Acetylated murein dimer fragments from Proteus mirabilis were much less active than their unsubstituted counterparts, indicating a structural specificity for murein activation. Removal of adherent and phagocytizing cells from the marrow suspensions did not alter these results. The labeled, activated cells constituted a distinct population of buoyant density 1.064 to 1.069 g/cm3 when centrifuged on a continuous gradient of Percoll. Enrichment of the target cell population was achieved by a combination of adherent cell removal and discontinuous density gradient centrifugation to remove granulocytes and erythropoietic cells. It was concluded that a population of myelopoietic precursors could be activated by direct contact with bacterial cell wall constituents. The stimulation of galactose incorporation was not coupled to active deoxyribonucleic acid synthesis in the marrow cells. Thus, the activation was interpreted as an induction of differentiation rather than a mitotic event. PMID:7014467

  6. XAS study of the active site of a bacterial heme-sensor

    NASA Astrophysics Data System (ADS)

    Della Longa, S.; Arcovito, A.; Brunori, M.; Castiglione, N.; Cutruzzolà, F.; D'Angelo, P.; Giardina, G.; Rinaldo, S.

    2009-11-01

    Denitrifying bacteria control NO and NO2 cytosolic levels by regulating the expression of denitrification gene clusters via REDOX signalling of specific transcriptional factors that may act as NO sensors in vivo. A protein belonging to the subclass DNR (dissimilative nitrate respiration regulator) from Pseudomonas aeruginosa has been recently suggested to be a heme containing protein. Very recently the three dimensional structure of the apo-form of DNR (in the absence of heme) has been determined by X-Ray crystallography, whereas the holo-form (in the presence of heme) has not yet been crystallized. We have investigated the heme local structure in solution of ferric and ferrous holo-DNR by XAS. The Fe K-edge XANES spectrum of the ferric adduct displays typical features of a low-spin hexacoordinate Fe-heme complex, having two histidines ligated. After chemical reduction, relevant changes of the XANES fingerprints suggest a repositioning of the heme inside the hydrophobic core of the protein in agreement with previously reported structural and spectroscopic evidence. Partial release of the axial ligands leaves the Fe(II)heme available, and very reactive, to bind exogenous ligands like NO, thus supporting its role as the cofactor involved in NO sensing activity.

  7. Active Flash: Out-of-core Data Analytics on Flash Storage

    SciTech Connect

    Boboila, Simona; Kim, Youngjae; Vazhkudai, Sudharshan S; Desnoyers, Peter; Shipman, Galen M

    2012-01-01

    Next generation science will increasingly come to rely on the ability to perform efficient, on-the-fly analytics of data generated by high-performance computing (HPC) simulations, modeling complex physical phenomena. Scientific computing workflows are stymied by the traditional chaining of simulation and data analysis, creating multiple rounds of redundant reads and writes to the storage system, which grows in cost with the ever-increasing gap between compute and storage speeds in HPC clusters. Recent HPC acquisitions have introduced compute node-local flash storage as a means to alleviate this I/O bottleneck. We propose a novel approach, Active Flash, to expedite data analysis pipelines by migrating to the location of the data, the flash device itself. We argue that Active Flash has the potential to enable true out-of-core data analytics by freeing up both the compute core and the associated main memory. By performing analysis locally, dependence on limited bandwidth to a central storage system is reduced, while allowing this analysis to proceed in parallel with the main application. In addition, offloading work from the host to the more power-efficient controller reduces peak system power usage, which is already in the megawatt range and poses a major barrier to HPC system scalability. We propose an architecture for Active Flash, explore energy and performance trade-offs in moving computation from host to storage, demonstrate the ability of appropriate embedded controllers to perform data analysis and reduction tasks at speeds sufficient for this application, and present a simulation study of Active Flash scheduling policies. These results show the viability of the Active Flash model, and its capability to potentially have a transformative impact on scientific data analysis.

  8. On-Demand Removal of Bacterial Biofilms via Shape Memory Activation.

    PubMed

    Gu, Huan; Lee, Sang Won; Buffington, Shelby Lois; Henderson, James H; Ren, Dacheng

    2016-08-24

    Bacterial biofilms are a major cause of chronic infections and biofouling; however, effective removal of established biofilms remains challenging. Here we report a new strategy for biofilm control using biocompatible shape memory polymers with defined surface topography. These surfaces can both prevent bacterial adhesion and remove established biofilms upon rapid shape change with moderate increase of temperature, thereby offering more prolonged antifouling properties. We demonstrate that this strategy can achieve a total reduction of Pseudomonas aeruginosa biofilms by 99.9% compared to the static flat control. It was also found effective against biofilms of Staphylococcus aureus and an uropathogenic strain of Escherichia coli. PMID:27517738

  9. Removing Cool Cores and Central Metallicity Peaks in Galaxy Clusters with Powerful Active Galactic Nucleus Outbursts

    NASA Astrophysics Data System (ADS)

    Guo, Fulai; Mathews, William G.

    2010-07-01

    Recent X-ray observations of galaxy clusters suggest that cluster populations are bimodally distributed according to central gas entropy and are separated into two distinct classes: cool core (CC) and non-cool core (NCC) clusters. While it is widely accepted that active galactic nucleus (AGN) feedback plays a key role in offsetting radiative losses and maintaining many clusters in the CC state, the origin of NCC clusters is much less clear. At the same time, a handful of extremely powerful AGN outbursts have recently been detected in clusters, with a total energy ~1061-1062 erg. Using two-dimensional hydrodynamic simulations, we show that if a large fraction of this energy is deposited near the centers of CC clusters, which is likely common due to dense cores, these AGN outbursts can completely remove CCs, transforming them to NCC clusters. Our model also has interesting implications for cluster abundance profiles, which usually show a central peak in CC systems. Our calculations indicate that during the CC to NCC transformation, AGN outbursts efficiently mix metals in cluster central regions and may even remove central abundance peaks if they are not broad enough. For CC clusters with broad central abundance peaks, AGN outbursts decrease peak abundances, but cannot effectively destroy the peaks. Our model may simultaneously explain the contradictory (possibly bimodal) results of abundance profiles in NCC clusters, some of which are nearly flat, while others have strong central peaks similar to those in CC clusters. A statistical analysis of the sizes of central abundance peaks and their redshift evolution may shed interesting insights on the origin of both types of NCC clusters and the evolution history of thermodynamics and AGN activity in clusters.

  10. Blockage of protease-activated receptor 1 ameliorates heat-stress induced intestinal high permeability and bacterial translocation.

    PubMed

    Xu, Qiu-lin; Guo, Xiao-hua; Liu, Jing-xian; Chen, Bin; Liu, Zhi-feng; Su, Lei

    2015-04-01

    Accumulated evidences indicate intestinal lesions play an important role in the pathogenesis of heatstroke. However, the underlying mechanisms by which heat stress causes intestinal barrier dysfunction and bacterial translocation remain unclear. In this study, we investigated the role of protease-activated receptor 1 (PAR1) in heat stress-induced intestinal hyper-permeability and bacterial translocation. Intestinal permeability in heat stressed mouse was evaluated by determining plasma endotoxin concentration and urinal lactulose/mannitol (L/M) ratio with gastric administration of L/M solution. Venous blood, liver, spleen and mesenteric lymph node tissues were collected for bacterial load test. Real time PCR was used to determine ileum PAR1 mRNA expression. In vitro study, permeability was assessed by determining trans-epithelial electrical resistance (TEER) in human intestinal Caco-2 cell line. RWJ-58259, a selective antagonist of PAR1, was used both in vivo and in vitro studies. The results showed that heat stress could increase ileum PAR1 mRNA level, urinal L/M ratio, plasma endotoxin concentration and bacterial load in the blood, spleen and mesenteric lymph nodes. Blocking PAR1 with RWJ-58259 (10 mg/kg) pretreatment could significantly reduce heat stress-induced above changes, but have no role to PAR1 mRNA level. In Caco-2 cells, heat stress-induced high permeability could also be reduced by RWJ-58259 (5-20 µmol/L). In summary, our results demonstrated that PAR1 signaling pathway may play an important role in the heat stress-induced elevation of intestinal permeability, bacterial translocation and the occurrence of endotoxemia. PMID:25492552

  11. Structure-Function Analysis of the Drosophila melanogaster Caudal Transcription Factor Provides Insights into Core Promoter-preferential Activation.

    PubMed

    Shir-Shapira, Hila; Sharabany, Julia; Filderman, Matan; Ideses, Diana; Ovadia-Shochat, Avital; Mannervik, Mattias; Juven-Gershon, Tamar

    2015-07-10

    Regulation of RNA polymerase II transcription is critical for the proper development, differentiation, and growth of an organism. The RNA polymerase II core promoter is the ultimate target of a multitude of transcription factors that control transcription initiation. Core promoters encompass the RNA start site and consist of functional elements such as the TATA box, initiator, and downstream core promoter element (DPE), which confer specific properties to the core promoter. We have previously discovered that Drosophila Caudal, which is a master regulator of genes involved in development and differentiation, is a DPE-specific transcriptional activator. Here, we show that the mouse Caudal-related homeobox (Cdx) proteins (mCdx1, mCdx2, and mCdx4) are also preferential core promoter transcriptional activators. To elucidate the mechanism that enables Caudal to preferentially activate DPE transcription, we performed structure-function analysis. Using a systematic series of deletion mutants (all containing the intact DNA-binding homeodomain) we discovered that the C-terminal region of Caudal contributes to the preferential activation of the fushi tarazu (ftz) Caudal target gene. Furthermore, the region containing both the homeodomain and the C terminus of Caudal was sufficient to confer core promoter-preferential activation to the heterologous GAL4 DNA-binding domain. Importantly, we discovered that Drosophila CREB-binding protein (dCBP) is a co-activator for Caudal-regulated activation of ftz. Strikingly, dCBP conferred the ability to preferentially activate the DPE-dependent ftz reporter to mini-Caudal proteins that were unable to preferentially activate ftz transcription themselves. Taken together, it is the unique combination of dCBP and Caudal that enables the co-activation of ftz in a core promoter-preferential manner. PMID:26018075

  12. A fluorescence-based assay for Core 1 β3galactosyltransferase (T-synthase) activity.

    PubMed

    Ju, Tongzhong; Cummings, Richard D

    2013-01-01

    Mucin-type O-glycans on glycoproteins in animal cells play important roles in many biological processes. Core 1 β3galactosyltransferase (Core 1 β3GalT, T-synthase) is a key enzyme in the O-glycan biosynthetic pathway. Emerging evidence has shown the importance of O-glycans and the absolute requirement of T-synthase in this pathway. The assessment of the T-synthase activity has historically been conducted using a radioactive method. Here we describe a fluorescence-based assay procedure for T-synthase activity. T-synthase utilizes the acceptor substrate 4-methylumbelliferone-α-GalNAc (GalNAcα-(4-MU)) and the donor substrate UDP-Gal to synthesize the disaccharide product Galβ1,3GalNAcα-(4-MU) structure. This product is specifically hydrolyzed by endo-α-N-acetylgalactosaminidase (O-glycosidase) releasing free 4-MU. Free 4-MU is highly fluorescent at pH 9.6-10 and can be easily measured by a fluorescent detector (Ex: 355 nm; Em: 460 nm). This fluorescence-based T-synthase assay is simple, sensitive, reproducible, not affected by enzyme source, and adaptable for high-throughput assays. PMID:23765650

  13. CAN A LONG NANOFLARE STORM EXPLAIN THE OBSERVED EMISSION MEASURE DISTRIBUTIONS IN ACTIVE REGION CORES?

    SciTech Connect

    Mulu-Moore, Fana M.; Winebarger, Amy R.; Warren, Harry P.

    2011-11-20

    All theories that attempt to explain the heating of the high-temperature plasma observed in the solar corona are based on short bursts of energy. The intensities and velocities measured in the cores of quiescent active regions, however, can be steady over many hours of observation. One heating scenario that has been proposed to reconcile such observations with impulsive heating models is the 'long nanoflare storm', where short-duration heating events occur infrequently on many sub-resolution strands; the emission of the strands is then averaged together to explain the observed steady structures. In this Letter, we examine the emission measure distribution predicted for such a long nanoflare storm by modeling an arcade of strands in an active region core. Comparisons of the computed emission measure distributions with recent observations indicate that the long nanoflare storm scenario implies greater than five times more 1 MK emission than is actually observed for all plausible combinations of loop lengths, heating rates, and abundances. We conjecture that if the plasma had 'super coronal' abundances, the model may be able to match the observations at low temperatures.

  14. Elemental abundances and temperatures of quiescent solar active region cores from X-ray observations

    NASA Astrophysics Data System (ADS)

    Del Zanna, G.; Mason, H. E.

    2014-05-01

    A brief review of studies of elemental abundances and emission measures in quiescent solar active region cores is presented. Hinode EUV Imaging Spectrometer (EIS) observations of strong iron spectral lines have shown sharply peaked distributions around 3 MK. EIS observations of lines emitted by a range of elements have allowed good estimates of abundances relative to iron. However, X-ray observations are required to measure the plasma emission above 3 MK and the abundances of oxygen and neon. We revisit, using up-to-date atomic data, older X-ray observations obtained by a sounding rocket and by the Solar Maximum Mission (SMM) Flat Crystal Spectrometer (FCS). We find that the Fe/O and Fe/Ne ratios are normally increased by a factor of 3.2, compared to the photospheric values. Similar results are obtained from FCS observations of six quiescent active region cores. The FCS observations also indicate that the emission measure above 3 MK has a very steep negative slope, with very little plasma observed at 5 MK or above. Appendix A is available in electronic form at http://www.aanda.org

  15. Preservice Secondary Teachers' Conceptions from a Mathematical Modeling Activity and Connections to the Common Core State Standards

    ERIC Educational Resources Information Center

    Stohlmann, Micah; Maiorca, Cathrine; Olson, Travis A.

    2015-01-01

    Mathematical modeling is an essential integrated piece of the Common Core State Standards. However, researchers have shown that mathematical modeling activities can be difficult for teachers to implement. Teachers are more likely to implement mathematical modeling activities if they have their own successful experiences with such activities. This…

  16. The Bacterial Communities of Full-Scale Biologically Active, Granular Activated Carbon Filters Are Stable and Diverse and Potentially Contain Novel Ammonia-Oxidizing Microorganisms

    PubMed Central

    Hope Wilkinson, Katheryn; Strait, Jacqueline M.; Hozalski, Raymond M.; Sadowksy, Michael J.; Hamilton, Matthew J.

    2015-01-01

    The bacterial community composition of the full-scale biologically active, granular activated carbon (BAC) filters operated at the St. Paul Regional Water Services (SPRWS) was investigated using Illumina MiSeq analysis of PCR-amplified 16S rRNA gene fragments. These bacterial communities were consistently diverse (Shannon index, >4.4; richness estimates, >1,500 unique operational taxonomic units [OTUs]) throughout the duration of the 12-month study period. In addition, only modest shifts in the quantities of individual bacterial populations were observed; of the 15 most prominent OTUs, the most highly variable population (a Variovorax sp.) modulated less than 13-fold over time and less than 8-fold from filter to filter. The most prominent population in the profiles was a Nitrospira sp., representing 13 to 21% of the community. Interestingly, very few of the known ammonia-oxidizing bacteria (AOB; <0.07%) and no ammonia-oxidizing Archaea were detected in the profiles. Quantitative PCR of amoA genes, however, suggested that AOB were prominent in the bacterial communities (amoA/16S rRNA gene ratio, 1 to 10%). We conclude, therefore, that the BAC filters at the SPRWS potentially contained significant numbers of unidentified and novel ammonia-oxidizing microorganisms that possess amoA genes similar to those of previously described AOB. PMID:26209671

  17. The Bacterial Communities of Full-Scale Biologically Active, Granular Activated Carbon Filters Are Stable and Diverse and Potentially Contain Novel Ammonia-Oxidizing Microorganisms.

    PubMed

    LaPara, Timothy M; Hope Wilkinson, Katheryn; Strait, Jacqueline M; Hozalski, Raymond M; Sadowksy, Michael J; Hamilton, Matthew J

    2015-10-01

    The bacterial community composition of the full-scale biologically active, granular activated carbon (BAC) filters operated at the St. Paul Regional Water Services (SPRWS) was investigated using Illumina MiSeq analysis of PCR-amplified 16S rRNA gene fragments. These bacterial communities were consistently diverse (Shannon index, >4.4; richness estimates, >1,500 unique operational taxonomic units [OTUs]) throughout the duration of the 12-month study period. In addition, only modest shifts in the quantities of individual bacterial populations were observed; of the 15 most prominent OTUs, the most highly variable population (a Variovorax sp.) modulated less than 13-fold over time and less than 8-fold from filter to filter. The most prominent population in the profiles was a Nitrospira sp., representing 13 to 21% of the community. Interestingly, very few of the known ammonia-oxidizing bacteria (AOB; <0.07%) and no ammonia-oxidizing Archaea were detected in the profiles. Quantitative PCR of amoA genes, however, suggested that AOB were prominent in the bacterial communities (amoA/16S rRNA gene ratio, 1 to 10%). We conclude, therefore, that the BAC filters at the SPRWS potentially contained significant numbers of unidentified and novel ammonia-oxidizing microorganisms that possess amoA genes similar to those of previously described AOB. PMID:26209671

  18. Active Transport of Phosphorylated Carbohydrates Promotes Intestinal Colonization and Transmission of a Bacterial Pathogen.

    PubMed

    Sit, Brandon; Crowley, Shauna M; Bhullar, Kirandeep; Lai, Christine Chieh-Lin; Tang, Calvin; Hooda, Yogesh; Calmettes, Charles; Khambati, Husain; Ma, Caixia; Brumell, John H; Schryvers, Anthony B; Vallance, Bruce A; Moraes, Trevor F

    2015-08-01

    Efficient acquisition of extracellular nutrients is essential for bacterial pathogenesis, however the identities and mechanisms for transport of many of these substrates remain unclear. Here, we investigate the predicted iron-binding transporter AfuABC and its role in bacterial pathogenesis in vivo. By crystallographic, biophysical and in vivo approaches, we show that AfuABC is in fact a cyclic hexose/heptose-phosphate transporter with high selectivity and specificity for a set of ubiquitous metabolites (glucose-6-phosphate, fructose-6-phosphate and sedoheptulose-7-phosphate). AfuABC is conserved across a wide range of bacterial genera, including the enteric pathogens EHEC O157:H7 and its murine-specific relative Citrobacter rodentium, where it lies adjacent to genes implicated in sugar sensing and acquisition. C. rodentium ΔafuA was significantly impaired in an in vivo murine competitive assay as well as its ability to transmit infection from an afflicted to a naïve murine host. Sugar-phosphates were present in normal and infected intestinal mucus and stool samples, indicating that these metabolites are available within the intestinal lumen for enteric bacteria to import during infection. Our study shows that AfuABC-dependent uptake of sugar-phosphates plays a critical role during enteric bacterial infection and uncovers previously unrecognized roles for these metabolites as important contributors to successful pathogenesis. PMID:26295949

  19. Antibacterial activity of plant extracts on foodborne bacterial pathogens and food spoilage bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial foodborne diseases are caused by consumption of foods contaminated with bacteria and/or their toxins. In this study, we evaluated antibacterial properties of twelve different extracts including turmeric, lemon and different kinds of teas against four major pathogenic foodborne bacteria inc...

  20. Active Transport of Phosphorylated Carbohydrates Promotes Intestinal Colonization and Transmission of a Bacterial Pathogen

    PubMed Central

    Sit, Brandon; Crowley, Shauna M.; Bhullar, Kirandeep; Lai, Christine Chieh-Lin; Tang, Calvin; Hooda, Yogesh; Calmettes, Charles; Khambati, Husain; Ma, Caixia; Brumell, John H.; Schryvers, Anthony B.; Vallance, Bruce A.; Moraes, Trevor F.

    2015-01-01

    Efficient acquisition of extracellular nutrients is essential for bacterial pathogenesis, however the identities and mechanisms for transport of many of these substrates remain unclear. Here, we investigate the predicted iron-binding transporter AfuABC and its role in bacterial pathogenesis in vivo. By crystallographic, biophysical and in vivo approaches, we show that AfuABC is in fact a cyclic hexose/heptose-phosphate transporter with high selectivity and specificity for a set of ubiquitous metabolites (glucose-6-phosphate, fructose-6-phosphate and sedoheptulose-7-phosphate). AfuABC is conserved across a wide range of bacterial genera, including the enteric pathogens EHEC O157:H7 and its murine-specific relative Citrobacter rodentium, where it lies adjacent to genes implicated in sugar sensing and acquisition. C. rodentium ΔafuA was significantly impaired in an in vivo murine competitive assay as well as its ability to transmit infection from an afflicted to a naïve murine host. Sugar-phosphates were present in normal and infected intestinal mucus and stool samples, indicating that these metabolites are available within the intestinal lumen for enteric bacteria to import during infection. Our study shows that AfuABC-dependent uptake of sugar-phosphates plays a critical role during enteric bacterial infection and uncovers previously unrecognized roles for these metabolites as important contributors to successful pathogenesis. PMID:26295949

  1. Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

    PubMed Central

    Gharamah, Abdullah A; Moharram, Ahmed M; Ismail, Mady A; AL-Hussaini, Ashraf K

    2014-01-01

    Purpose: This work was conducted to study the ability of bacterial and fungal isolates from keratitis cases in Upper Egypt to produce enzymes, toxins, and to test the isolated fungal species sensitivity to some therapeutic agents. Materials and Methods: One hundred and fifteen patients clinically diagnosed to have microbial keratitis were investigated. From these cases, 37 bacterial isolates and 25 fungal isolates were screened for their ability to produce extra-cellular enzymes in solid media. In addition, the ability of fungal isolates to produce mycotoxins and their sensitivity to 4 antifungal agents were tested. Results: Protease, lipase, hemolysins, urease, phosphatase, and catalase were detected respectively in 48.65%, 37.84%, 59.46%, 43.24%, 67.57%, and 100% out of 37 bacterial isolates tested. Out of 25 fungal isolates tested during the present study, 80% were positive for protease, 84% for lipase and urease, 28% for blood hemolysis, and 100% for phosphatase and catalase enzymes. Thirteen fungal isolates were able to produce detectable amounts of 7 mycotoxins in culture medium (aflatoxins (B1, B2, G1, and G2), sterigmatocystin, fumagillin, diacetoxyscirpenol, zearalenone, T-2 toxin, and trichodermin). Among the antifungal agents tested in this study, terbinafine showed the highest effect against most isolates in vitro. Conclusion: In conclusion, the ability of bacterial and fungal isolates to produce extracellular enzymes and toxins may be aid in the invasion and destruction of eye tissues, which, in turn, lead to vision loss. PMID:24008795

  2. Bacterial delta-aminolevulinic acid synthase activity is not essential for leghemoglobin formation in the soybean/Bradyrhizobium japonicum symbiosis

    SciTech Connect

    Guerinot, M.L.; Chelm, B.K.

    1986-03-01

    Previous studies of legume nodules have indicated that formation of the heme moiety of leghemoglobin is a function of the bacterial symbiont. The authors now show that a hemA mutant of Bradyrhizobium japonicum that cannot carry out the first step in heme biosynthesis forms fully effective nodules on soybeans. The bacterial mutant strain was constructed by first isolated the wild-type hemA gene encoding delta-aminolevulinic acid synthase (EC 2.3.1.37) from a cosmid library, using a fragment of the Rhizobium meliloti hemA gene as a hybridization probe. A deletion of the hemA gene region, generated in vitro, then was used to construct the analogous chromosomal mutation by gene-directed mutagenesis. The mutant strain had no delta-aminolevulinic acid synthase activity and was unable to grow in minimal medium unless delta-aminolevulinic acid was added. Despite its auxotrophy, the mutant strain incited nodules that appeared normal, contained heme, and were capable of high levels of acetylene reduction. These results rule out bacterial delta-aminolevulinic acid synthase activity as the exclusive source of delta-aminolevulinic acid for heme formation in soybean nodules.

  3. Removal of two waterborne pathogenic bacterial strains by activated carbon particles prior to and after charge modification.

    PubMed

    Busscher, Henk J; Dijkstra, Rene J B; Engels, Eefje; Langworthy, Don E; Collias, Dimitris I; Bjorkquist, David W; Mitchell, Michael D; Van der Mei, Henny C

    2006-11-01

    Waterborne diseases constitute a threat to public health despite costly treatment measures aimed at removing pathogenic microorganisms from potable water supplies. This paper compared the removal of Raoultella terrigena ATCC 33257 and Escherichia coli ATCC 25922 by negatively and positively charged types of activated carbon particles. Both strains display bimodal negative zeta-potential distributions in stabilized water. Carbon particles were suspended to an equivalent external geometric surface area of 700 cm2 in 250 mL of a bacterial suspension, with shaking. Samples were taken after different durations for plate counting. Initial removal rates were less elevated for the positively charged carbon particle than expected, yielding the conclusion that bacterial adhesion under shaking is mass-transport limited. After 360 min, however, the log-reduction of the more negatively charged R. terrigena in suspension was largest for the positively charged carbon particles as compared with the negatively charged ones, although conditioning in ultrapure or tap water of positively charged carbon particles for 21 days eliminated the favorable effect of the positive charge due to counterion adsorption from the water. Removal of the less negatively charged E. coli was less affected by aging of the (positively charged) carbon particles, confirming the role of electrostatic interactions in bacterial removal by activated carbon particles. The microporous, negatively charged coconut carbon performed less than the mesoporous, positively charged carbon particle prior to conditioning but did not suffer from loss of effect after conditioning in ultrapure or tap water. PMID:17144313

  4. Discovery and structure-activity relationships of a novel isothiazolone class of bacterial type II topoisomerase inhibitors.

    PubMed

    Cooper, Ian R; McCarroll, Andrew J; McGarry, David; Kirkham, James; Pichowicz, Mark; Walker, Rolf; Warrilow, Catherine; Salisbury, Anne-Marie; Savage, Victoria J; Moyo, Emmanuel; Forward, Henry; Cheung, Jonathan; Metzger, Richard; Gault, Zoe; Nelson, Gary; Hughes, Diarmaid; Cao, Sha; Maclean, John; Charrier, Cédric; Craighead, Mark; Best, Stuart; Stokes, Neil R; Ratcliffe, Andrew J

    2016-09-01

    There is an urgent and unmet medical need for new antibacterial drugs that tackle infections caused by multidrug-resistant (MDR) pathogens. During the course of our wider efforts to discover and exploit novel mechanism of action antibacterials, we have identified a novel series of isothiazolone based inhibitors of bacterial type II topoisomerase. Compounds from the class displayed excellent activity against both Gram-positive and Gram-negative bacteria with encouraging activity against a panel of MDR clinical Escherichia coli isolates when compared to ciprofloxacin. Representative compounds also displayed a promising in vitro safety profile. PMID:27499455

  5. Anti-Pseudomonas aeruginosa IgY antibodies promote bacterial opsonization and augment the phagocytic activity of polymorphonuclear neutrophils.

    PubMed

    Thomsen, Kim; Christophersen, Lars; Jensen, Peter Østrup; Bjarnsholt, Thomas; Moser, Claus; Høiby, Niels

    2016-07-01

    Moderation of polymorphonuclear neutrophils (PMNs) as part of a critical defense against invading pathogens may offer a promising therapeutic approach to supplement the antibiotic eradication of Pseudomonas aeruginosa infection in non-chronically infected cystic fibrosis (CF) patients. We have observed that egg yolk antibodies (IgY) harvested from White leghorn chickens that target P. aeruginosa opsonize the pathogen and enhance the PMN-mediated respiratory burst and subsequent bacterial killing in vitro. The effects on PMN phagocytic activity were observed in different Pseudomonas aeruginosa strains, including clinical isolates from non-chronically infected CF patients. Thus, oral prophylaxis with anti-Pseudomonas aeruginosa IgY may boost the innate immunity against Pseudomonas aeruginosa in the CF setting by facilitating a rapid and prompt bacterial clearance by PMNs. PMID:26901841

  6. Sequences flanking the core-binding site modulate glucocorticoid receptor structure and activity.

    PubMed

    Schöne, Stefanie; Jurk, Marcel; Helabad, Mahdi Bagherpoor; Dror, Iris; Lebars, Isabelle; Kieffer, Bruno; Imhof, Petra; Rohs, Remo; Vingron, Martin; Thomas-Chollier, Morgane; Meijsing, Sebastiaan H

    2016-01-01

    The glucocorticoid receptor (GR) binds as a homodimer to genomic response elements, which have particular sequence and shape characteristics. Here we show that the nucleotides directly flanking the core-binding site, differ depending on the strength of GR-dependent activation of nearby genes. Our study indicates that these flanking nucleotides change the three-dimensional structure of the DNA-binding site, the DNA-binding domain of GR and the quaternary structure of the dimeric complex. Functional studies in a defined genomic context show that sequence-induced changes in GR activity cannot be explained by differences in GR occupancy. Rather, mutating the dimerization interface mitigates DNA-induced changes in both activity and structure, arguing for a role of DNA-induced structural changes in modulating GR activity. Together, our study shows that DNA sequence identity of genomic binding sites modulates GR activity downstream of binding, which may play a role in achieving regulatory specificity towards individual target genes. PMID:27581526

  7. Bacterial community dynamics and activity in relation to dissolved organic matter availability during sea-ice formation in a mesocosm experiment.

    PubMed

    Eronen-Rasimus, Eeva; Kaartokallio, Hermanni; Lyra, Christina; Autio, Riitta; Kuosa, Harri; Dieckmann, Gerhard S; Thomas, David N

    2014-02-01

    The structure of sea-ice bacterial communities is frequently different from that in seawater. Bacterial entrainment in sea ice has been studied with traditional microbiological, bacterial abundance, and bacterial production methods. However, the dynamics of the changes in bacterial communities during the transition from open water to frozen sea ice is largely unknown. Given previous evidence that the nutritional status of the parent water may affect bacterial communities during ice formation, bacterial succession was studied in under ice water and sea ice in two series of mesocosms: the first containing seawater from the North Sea and the second containing seawater enriched with algal-derived dissolved organic matter (DOM). The composition and dynamics of bacterial communities were investigated with terminal restriction fragment length polymorphism (T-RFLP), and cloning alongside bacterial production (thymidine and leucine uptake) and abundance measurements (measured by flow cytometry). Enriched and active sea-ice bacterial communities developed in ice formed in both unenriched and DOM-enriched seawater (0-6 days). γ-Proteobacteria dominated in the DOM-enriched samples, indicative of their capability for opportunistic growth in sea ice. The bacterial communities in the unenriched waters and ice consisted of the classes Flavobacteria, α- and γ-Proteobacteria, which are frequently found in natural sea ice in polar regions. Furthermore, the results indicate that seawater bacterial communities are able to adapt rapidly to sudden environmental changes when facing considerable physicochemical stress such as the changes in temperature, salinity, nutrient status, and organic matter supply during ice formation. PMID:24443388

  8. Bacterial community dynamics and activity in relation to dissolved organic matter availability during sea-ice formation in a mesocosm experiment

    PubMed Central

    Eronen-Rasimus, Eeva; Kaartokallio, Hermanni; Lyra, Christina; Autio, Riitta; Kuosa, Harri; Dieckmann, Gerhard S; Thomas, David N

    2014-01-01

    The structure of sea-ice bacterial communities is frequently different from that in seawater. Bacterial entrainment in sea ice has been studied with traditional microbiological, bacterial abundance, and bacterial production methods. However, the dynamics of the changes in bacterial communities during the transition from open water to frozen sea ice is largely unknown. Given previous evidence that the nutritional status of the parent water may affect bacterial communities during ice formation, bacterial succession was studied in under ice water and sea ice in two series of mesocosms: the first containing seawater from the North Sea and the second containing seawater enriched with algal-derived dissolved organic matter (DOM). The composition and dynamics of bacterial communities were investigated with terminal restriction fragment length polymorphism (T-RFLP), and cloning alongside bacterial production (thymidine and leucine uptake) and abundance measurements (measured by flow cytometry). Enriched and active sea-ice bacterial communities developed in ice formed in both unenriched and DOM-enriched seawater (0–6 days). γ-Proteobacteria dominated in the DOM-enriched samples, indicative of their capability for opportunistic growth in sea ice. The bacterial communities in the unenriched waters and ice consisted of the classes Flavobacteria, α-and γ-Proteobacteria, which are frequently found in natural sea ice in polar regions. Furthermore, the results indicate that seawater bacterial communities are able to adapt rapidly to sudden environmental changes when facing considerable physicochemical stress such as the changes in temperature, salinity, nutrient status, and organic matter supply during ice formation. PMID:24443388

  9. Bacterial Community Dynamics in Full-Scale Activated Sludge Bioreactors: Operational and Ecological Factors Driving Community Assembly and Performance

    PubMed Central

    Valentín-Vargas, Alexis; Toro-Labrador, Gladys; Massol-Deyá, Arturo A.

    2012-01-01

    The assembling of bacterial communities in conventional activated sludge (CAS) bioreactors was thought, until recently, to be chaotic and mostly unpredictable. Studies done over the last decade have shown that specific, and often, predictable random and non-random factors could be responsible for that process. These studies have also motivated a “structure–function” paradigm that is yet to be resolved. Thus, elucidating the factors that affect community assembly in the bioreactors is necessary for predicting fluctuations in community structure and function. For this study activated sludge samples were collected during a one-year period from two geographically distant CAS bioreactors of different size. Combining community fingerprinting analysis and operational parameters data with a robust statistical analysis, we aimed to identify relevant links between system performance and bacterial community diversity and dynamics. In addition to revealing a significant β-diversity between the bioreactors’ communities, results showed that the largest bioreactor had a less dynamic but more efficient and diverse bacterial community throughout the study. The statistical analysis also suggests that deterministic factors, as opposed to stochastic factors, may have a bigger impact on the community structure in the largest bioreactor. Furthermore, the community seems to rely mainly on mechanisms of resistance and functional redundancy to maintain functional stability. We suggest that the ecological theories behind the Island Biogeography model and the species-area relationship were appropriate to predict the assembly of bacterial communities in these CAS bioreactors. These results are of great importance for engineers and ecologists as they reveal critical aspects of CAS systems that could be applied towards improving bioreactor design and operation. PMID:22880016

  10. [Algicidal activity against red-tide algaes by marine bacterial strain N3 isolated from a HABs area, southern China].

    PubMed

    Shi, Rong-jun; Huang, Hong-hui; Qi, Zhan-hui; Hu, Wei-an; Tian, Zi-yang; Dai, Ming

    2013-05-01

    A marine algicidal bacterium N3 was isolated from a HABs area in Mirs Bay, a subtropical bay, in southern China. Algicidal activity and algicidal mode against Phaeodactylum tricornutum, Scrippsiella trochoidea, Prorocentrum micans and Skeletonema costatum were observed by the liquid infection method. The results showed that there were no algicidal activities against P. tricornutum and S. costatum. However, when the bacterial volume fractions were 2% and 10% , S. trochoidea and P. micans could be killed, respectively. S. trochoidea cells which were exposed to strain N3 became irregular in shape and the cellular components lost their integrity and were decomposed. While, the P. micans cells became inflated and the cellular components aggregated, followed by cell lysis. Strain N3 killed S. trochoidea and P. micans directly, and the algicidal activities of the bacterial strain N3 was concentration-dependent. To S. trochoidea, 2% (V/V) of bacteria in algae showed the strongest algicidal activity, all of the S. trochoidea cells were killed within 120 h. But the growth rates of cells, in the 1% and 0. 1% treatment groups, were only slightly lower than that in the control group. In all treatment groups, the densities of strain N3 were in declining trends. While, to P. micans, 10% and 5% of bacteria in algae showed strong algicidal activities, 78% and 70% of the S. trochoidea were killed within 120 h, respectively. However, the number of S. trochoidea after exposure to 1% of bacterial cultures still increased up to 5 incubation days. And in the three treatment groups, the densities of strain N3 experienced a decrease process. The isolated strain N3 was identified as Bacillus sp. by morphological observation, physiological and biochemical characterization, and homology comparisons based on 16S rRNA sequences. PMID:23914549

  11. Modulation of Toll-Like Receptor Activity by Leukocyte Ig-Like Receptors and Their Effects during Bacterial Infection

    PubMed Central

    Pilsbury, Louise E.; Allen, Rachel L.; Vordermeier, Martin

    2010-01-01

    Toll-like receptors (TLRs) are a potent trigger for inflammatory immune responses. Without tight regulation their activation could lead to pathology, so it is imperative to extend our understanding of the regulatory mechanisms that govern TLR expression and function. One family of immunoregulatory proteins which can provide a balancing effect on TLR activity are the Leukocyte Ig-like receptors (LILRs), which act as innate immune receptors for self-proteins. Here we describe the LILR family, their inhibitory effect on TLR activity in cells of the monocytic lineage, their signalling pathway, and their antimicrobial effects during bacterial infection. Agents have already been identified which enhances or inhibits LILR activity raising the future possibility that modulation of LILR function could be used as a means to modulate TLR activity. PMID:20634939

  12. Effects of an enteric anaerobic bacterial culture supernatant and deoxycholate on intestinal calcium absorption and disaccharidase activity.

    PubMed Central

    Walshe, K; Healy, M J; Speekenbrink, A B; Keane, C T; Weir, D G; O'Moore, R R

    1990-01-01

    Fifty two strains of anaerobic bacteria isolated from the upper gut of patients with small intestinal bacterial overgrowth were screened for phospholipase activity. Bacteroides melaninogenicus spp intermedius had the greatest activity. The effects of culture supernatants of this organism and deoxycholate on intestinal calcium absorption and disaccharidase activity were studied using a rat closed loop model. The supernatant decreased the in vitro uptake of calcium by 15% (p less than 0.001). Deoxycholate reduced calcium uptake by 16% (p less than 0.001). Combined culture supernatant and deoxycholate reduced calcium uptake by 39% (p less than 0.001) suggesting a potentiation of supernatant activity by deoxycholate. Culture supernatant and deoxycholate, both alone and combined, significantly reduced lactase, sucrase, and maltase activity. Electron microscopic evidence showed degeneration of microvilli, disruption of mitochondrial structure, and swelling of the endoplasmic reticulum after exposure of the intestinal loops to the supernatant or deoxycholate. Images Figure 2 Figure 3 Figure 4 PMID:1973395

  13. Screening for antibacterial activity of some Turkish plants against fish pathogens: a possible alternative in the treatment of bacterial infections

    PubMed Central

    Turker, Hakan; Yıldırım, Arzu Birinci

    2015-01-01

    The antibacterial activity of ethanolic and aqueous crude extracts from 36 plants in Turkey, including seven endemic species, against fish pathogens was studied using the disc diffusion assay. The extract that was most active against all microbial strains, except Aeromonas salmonicida, was that of Dorycnium pentaphyllum. Some of the extracts also showed a very broad spectrum of potent antimicrobial activity. The extract of Anemone nemorosa showed the highest antimicrobial activity against Vibrio anguillarum. V. anguillarum, a Gram-negative bacterium, appeared to be the most susceptible to the plant extracts used in this experiment. To the best of our knowledge, this is the first report on the antimicrobial activity of 11 of the studied plants. The preliminary screening assay indicated that some of the Turkish plants with antibacterial properties may offer alternative therapeutic agents against bacterial infections in aquaculture industry. PMID:26019642

  14. DIAGNOSING THE TIME DEPENDENCE OF ACTIVE REGION CORE HEATING FROM THE EMISSION MEASURE. II. NANOFLARE TRAINS

    SciTech Connect

    Reep, J. W.; Bradshaw, S. J.; Klimchuk, J. A. E-mail: stephen.bradshaw@rice.edu

    2013-02-20

    The time dependence of heating in solar active regions can be studied by analyzing the slope of the emission measure distribution coolward of the peak. In a previous study we showed that low-frequency heating can account for 0% to 77% of active region core emission measures. We now turn our attention to heating by a finite succession of impulsive events for which the timescale between events on a single magnetic strand is shorter than the cooling timescale. We refer to this scenario as a 'nanoflare train' and explore a parameter space of heating and coronal loop properties with a hydrodynamic model. Our conclusions are (1) nanoflare trains are consistent with 86% to 100% of observed active region cores when uncertainties in the atomic data are properly accounted for; (2) steeper slopes are found for larger values of the ratio of the train duration {Delta} {sub H} to the post-train cooling and draining timescale {Delta} {sub C}, where {Delta} {sub H} depends on the number of heating events, the event duration and the time interval between successive events ({tau} {sub C}); (3) {tau} {sub C} may be diagnosed from the width of the hot component of the emission measure provided that the temperature bins are much smaller than 0.1 dex; (4) the slope of the emission measure alone is not sufficient to provide information about any timescale associated with heating-the length and density of the heated structure must be measured for {Delta} {sub H} to be uniquely extracted from the ratio {Delta} {sub H}/{Delta} {sub C}.

  15. Radiocarbon Evidence of Active Endolithic Microbial Communities in the Hyperarid Core of the Atacama Desert

    PubMed Central

    Wierzchos, Jacek; Davila, Alfonso F.; Slater, Gregory F.

    2013-01-01

    Abstract The hyperarid core of the Atacama Desert is one of the driest and most inhospitable places on Earth, where life is most commonly found in the interior of rocks (i.e., endolithic habitats). Due to the extreme dryness, microbial activity in these habitats is expected to be low; however, the rate of carbon cycling within these microbial communities remains unknown. We address this issue by characterizing the isotopic composition (13C and 14C) of phospholipid fatty acids (PLFA) and glycolipid fatty acids (GLFA) in colonized rocks from four different sites inside the hyperarid core. δ13C results suggest that autotrophy and/or quantitative conversion of organic matter to CO2 are the dominant processes occurring with the rock. Most Δ14C signatures of PLFA and GLFA were consistent with modern atmospheric CO2, indicating that endoliths are using atmospheric carbon as a primary carbon source and are also cycling carbon quickly. However, at one site the PLFA contained 14C from atmospheric nuclear weapons testing that occurred during the 1950s and 1960s, indicating a decadal rate of carbon cycling. At the driest site (Yungay), based on the relative abundance and 14C content of GLFA and PLFA, there was evidence of possible preservation. Hence, in low-moisture conditions, glycolipids may persist while phospholipids are preferentially hydrolyzed. Key Words: Endoliths—Extremophile—Carbon isotopes—Radiocarbon—Lipids. Astrobiology 13, 607–616. PMID:23848470

  16. Modeling active galactic nucleus feedback in cool-core clusters: The formation of cold clumps

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-10

    We perform high-resolution (15-30 pc) adaptive mesh simulations to study the impact of momentum-driven active galactic nucleus (AGN) feedback in cool-core clusters, focusing in this paper on the formation of cold clumps. The feedback is jet-driven with an energy determined by the amount of cold gas within 500 pc of the super-massive black hole. When the intracluster medium in the core of the cluster becomes marginally stable to radiative cooling, with the thermal instability to the free-fall timescale ratio t{sub TI}/t{sub ff} < 3-10, cold clumps of gas start to form along the propagation direction of the AGN jets. By tracing the particles in the simulations, we find that these cold clumps originate from low entropy (but still hot) gas that is accelerated by the jet to outward radial velocities of a few hundred km s{sup –1}. This gas is out of hydrostatic equilibrium and so can cool. The clumps then grow larger as they decelerate and fall toward the center of the cluster, eventually being accreted onto the super-massive black hole. The general morphology, spatial distribution, and estimated Hα morphology of the clumps are in reasonable agreement with observations, although we do not fully replicate the filamentary morphology of the clumps seen in the observations, probably due to missing physics.

  17. Core microbial functional activities in ocean environments revealed by global metagenomic profiling analyses.

    PubMed

    Ferreira, Ari J S; Siam, Rania; Setubal, João C; Moustafa, Ahmed; Sayed, Ahmed; Chambergo, Felipe S; Dawe, Adam S; Ghazy, Mohamed A; Sharaf, Hazem; Ouf, Amged; Alam, Intikhab; Abdel-Haleem, Alyaa M; Lehvaslaiho, Heikki; Ramadan, Eman; Antunes, André; Stingl, Ulrich; Archer, John A C; Jankovic, Boris R; Sogin, Mitchell; Bajic, Vladimir B; El-Dorry, Hamza

    2014-01-01

    Metagenomics-based functional profiling analysis is an effective means of gaining deeper insight into the composition of marine microbial populations and developing a better understanding of the interplay between the functional genome content of microbial communities and abiotic factors. Here we present a comprehensive analysis of 24 datasets covering surface and depth-related environments at 11 sites around the world's oceans. The complete datasets comprises approximately 12 million sequences, totaling 5,358 Mb. Based on profiling patterns of Clusters of Orthologous Groups (COGs) of proteins, a core set of reference photic and aphotic depth-related COGs, and a collection of COGs that are associated with extreme oxygen limitation were defined. Their inferred functions were utilized as indicators to characterize the distribution of light- and oxygen-related biological activities in marine environments. The results reveal that, while light level in the water column is a major determinant of phenotypic adaptation in marine microorganisms, oxygen concentration in the aphotic zone has a significant impact only in extremely hypoxic waters. Phylogenetic profiling of the reference photic/aphotic gene sets revealed a greater variety of source organisms in the aphotic zone, although the majority of individual photic and aphotic depth-related COGs are assigned to the same taxa across the different sites. This increase in phylogenetic and functional diversity of the core aphotic related COGs most probably reflects selection for the utilization of a broad range of alternate energy sources in the absence of light. PMID:24921648

  18. Core Microbial Functional Activities in Ocean Environments Revealed by Global Metagenomic Profiling Analyses

    PubMed Central

    Ferreira, Ari J. S.; Siam, Rania; Setubal, João C.; Moustafa, Ahmed; Sayed, Ahmed; Chambergo, Felipe S.; Dawe, Adam S.; Ghazy, Mohamed A.; Sharaf, Hazem; Ouf, Amged; Alam, Intikhab; Abdel-Haleem, Alyaa M.; Lehvaslaiho, Heikki; Ramadan, Eman; Antunes, André; Stingl, Ulrich; Archer, John A. C.; Jankovic, Boris R.; Sogin, Mitchell; Bajic, Vladimir B.; El-Dorry, Hamza

    2014-01-01

    Metagenomics-based functional profiling analysis is an effective means of gaining deeper insight into the composition of marine microbial populations and developing a better understanding of the interplay between the functional genome content of microbial communities and abiotic factors. Here we present a comprehensive analysis of 24 datasets covering surface and depth-related environments at 11 sites around the world's oceans. The complete datasets comprises approximately 12 million sequences, totaling 5,358 Mb. Based on profiling patterns of Clusters of Orthologous Groups (COGs) of proteins, a core set of reference photic and aphotic depth-related COGs, and a collection of COGs that are associated with extreme oxygen limitation were defined. Their inferred functions were utilized as indicators to characterize the distribution of light- and oxygen-related biological activities in marine environments. The results reveal that, while light level in the water column is a major determinant of phenotypic adaptation in marine microorganisms, oxygen concentration in the aphotic zone has a significant impact only in extremely hypoxic waters. Phylogenetic profiling of the reference photic/aphotic gene sets revealed a greater variety of source organisms in the aphotic zone, although the majority of individual photic and aphotic depth-related COGs are assigned to the same taxa across the different sites. This increase in phylogenetic and functional diversity of the core aphotic related COGs most probably reflects selection for the utilization of a broad range of alternate energy sources in the absence of light. PMID:24921648

  19. Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

    PubMed

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Kamari, Halimah Mohamed; Kong, Yap Chee; Hamzah, Mohd Suhaimi; Elias, Md Suhaimi

    2016-01-01

    A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82. PMID:26405840

  20. Prediction of hammerhead ribozyme intracellular activity with the catalytic core fingerprint.

    PubMed

    Gabryelska, Marta Magdalena; Wyszko, Eliza; Szymański, Maciej; Popenda, Mariusz; Barciszewski, Jan

    2013-05-01

    Hammerhead ribozyme is a versatile tool for down-regulation of gene expression in vivo. Owing to its small size and high activity, it is used as a model for RNA structure-function relationship studies. In the present paper we describe a new extended hammerhead ribozyme HH-2 with a tertiary stabilizing motif constructed on the basis of the tetraloop receptor sequence. This ribozyme is very active in living cells, but shows low activity in vitro. To understand it, we analysed tertiary structure models of substrate-ribozyme complexes. We calculated six unique catalytic core geometry parameters as distances and angles between particular atoms that we call the ribozyme fingerprint. A flanking sequence and tertiary motif change the geometry of the general base, general acid, nucleophile and leaving group. We found almost complete correlation between these parameters and the decrease of target gene expression in the cells. The tertiary structure model calculations allow us to predict ribozyme intracellular activity. Our approach could be widely adapted to characterize catalytic properties of other RNAs. PMID:23418809

  1. Structure of Arabidopsis thaliana 5-methylthioribose Kinase Reveals a More Occluded Active Site Than its Bacterial Homolog

    SciTech Connect

    Ku,S.; Cornell, K.; Howell, P.

    2007-01-01

    Metabolic variations exist between the methionine salvage pathway of humans and a number of plants and microbial pathogens. 5-Methylthioribose (MTR) kinase is a key enzyme required for methionine salvage in plants and many bacteria. The absence of a mammalian homolog suggests that MTR kinase is a good target for the design of specific herbicides or antibiotics. The structure of Arabidopsis thaliana MTR kinase co-crystallized with ATP?S and MTR has been determined at 1.9 Angstroms resolution. The structure is similar to B. subtilis MTR kinase and has the same protein kinase fold observed in other evolutionarily related protein kinase-like phosphotransferases. The active site is comparable between the two enzymes with the DXE-motif coordinating the nucleotide-Mg, the D238 of the HGD catalytic loop polarizing the MTR O1 oxygen, and the RR-motif interacting with the substrate MTR. Unlike its bacterial homolog, however, the Gly-rich loop (G-loop) of A. thaliana MTR kinase has an extended conformation, which shields most of the active site from solvent, a feature that resembles eukaryotic protein kinases more than the bacterial enzyme. The G- and W-loops of A. thaliana and B. subtilis MTR kinase adopt different conformations despite high sequence similarity. The ATP?S analog was hydrolyzed during the co-crystallization procedure, resulting in ADP in the active site. This suggests that the A. thaliana enzyme, like its bacterial homolog, may have significant ATPase activity in the absence of MTR. The structure of A. thaliana MTR kinase provides a template for structure-based design of agrochemicals, particularly herbicides whose effectiveness could be regulated by nutrient levels. Features of the MTR binding site offer an opportunity for a simple organic salt of an MTR analog to specifically inhibit MTR kinase.

  2. Diversity of culturable bacterial populations associated to Tuber borchii ectomycorrhizas and their activity on T. borchii mycelial growth.

    PubMed

    Sbrana, Cristiana; Agnolucci, Monica; Bedini, Stefano; Lepera, Annamaria; Toffanin, Annita; Giovannetti, Manuela; Nuti, Marco P

    2002-06-01

    Isolation and physiological and molecular characterisation of culturable bacterial strains belonging to actinomycetes, pseudomonads and aerobic spore-forming bacteria were carried out on mycorrhizal root tips of Quercus robur var. peduncolata infected by Tuber borchii. Cellular density of the three bacterial groups in ectomycorrhizal root tips was estimated to be 1.3+/-0.11 x 10(6) cfu g(-1) dry weight for total heterotrophic bacteria and 1.08+/-0.6 x 10(5) (mean+/-S.E.), 1.3+/-0.3 x 10(5) and 1.4+/-0.2 x 10(5) cfu g(-1) dry weight for pseudomonads, actinomycetes and spore-forming bacteria respectively. Identification of pseudomonads by the Biolog system indicated, besides the most represented species Pseudomonas fluorescens (biotypes B, F and G), the occurrence of strains belonging to Pseudomonas corrugata. Amplified ribosomal DNA restriction analysis of actinomycetes and spore formers revealed at least three and six different groups of patterns, respectively. Many bacterial isolates were able to induce variations in growth rates of T. borchii mycelium; among these, 101 strains showed antifungal activity, whereas 17 isolates, belonging to spore formers, were able to increase mycelial growth up to 78% when compared to uninoculated mycelial growth. The potential role of these populations in the development and establishment of mycorrhizas is discussed. PMID:12076812

  3. Conjugative DNA transfer induces the bacterial SOS response and promotes antibiotic resistance development through integron activation.

    PubMed

    Baharoglu, Zeynep; Bikard, David; Mazel, Didier

    2010-10-01

    Conjugation is one mechanism for intra- and inter-species horizontal gene transfer among bacteria. Conjugative elements have been instrumental in many bacterial species to face the threat of antibiotics, by allowing them to evolve and adapt to these hostile conditions. Conjugative plasmids are transferred to plasmidless recipient cells as single-stranded DNA. We used lacZ and gfp fusions to address whether conjugation induces the SOS response and the integron integrase. The SOS response controls a series of genes responsible for DNA damage repair, which can lead to recombination and mutagenesis. In this manuscript, we show that conjugative transfer of ssDNA induces the bacterial SOS stress response, unless an anti-SOS factor is present to alleviate this response. We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements. Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell. Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria. PMID:20975940

  4. Structure, Function and On-Off Switching of a Core Unit Contact between CheA Kinase and CheW Adaptor Protein in the Bacterial Chemosensory Array: A Disulfide Mapping and TAM-IDS Study

    PubMed Central

    Natale, Andrew M.; Duplantis, Jane L.; Piasta, Kene N.; Falke, Joseph J.

    2014-01-01

    The ultrasensitive, ultrastable bacterial chemosensory array of Escherichia coli and Salmonella typhimurium is representative of the large, conserved family of sensory arrays that control the cellular chemotaxis of motile bacteria and Archaea. The core framework of the membrane-bound array is a lattice assembled from three components: a transmembrane receptor, a cytoplasmic His kinase (CheA), and a cytoplasmic adaptor protein (CheW). Structural studies in the field have revealed the global architecture of the array and complexes between specific components, but much remains to be learned about the essential protein-protein interfaces that define array structure and transmit signals between components. This study has focused on the structure, function and on-off switching of a key contact between the kinase and adaptor proteins in the working, membrane-bound array. Specifically, the study addressed interface 1 in the putative kinase-adaptor ring where subdomain 1 of the kinase regulatory domain contacts subdomain 2 of the adaptor protein. Two independent approaches – disulfide mapping and site-directed Trp and Ala mutagenesis – were employed to (i) test the structural model of interface 1 and (ii) investigate its functional roles in both stable kinase incorporation and receptor-regulated kinase on-off switching. Studies were carried out in functional, membrane-bound arrays or in live cells. The findings reveal that crystal structures of binary and ternary complexes accurately depict the native interface in its kinase-activating on state. Furthermore, the findings indicate that at least part of the interface becomes less closely packed in its kinase-inhibiting off state. Together, the evidence shows the interface has a dual structural and signaling function that is crucial for stable kinase incorporation into the array, for kinase activation in the array on state, and likely for attractant-triggered kinase on-off switching. A model is presented that describes the

  5. Temperature Analysis of an Active Region Core Loop Using AIA and XRT Data

    NASA Astrophysics Data System (ADS)

    Garst, Jennifer W.; Schmelz, J.; Kimble, J.

    2012-05-01

    Data obtained on December 10, 2010 by both the Atmospheric Imaging Assembly (AIA) and the X-Ray Telescope (XRT) are co-aligned and appropriately scaled in order to do a differential emission measure analysis of the combined data. This project uses Hybrid abundances from Fludra & Schmelz and atomic data from the CHIANTI atomic physics database to analyze an active region core loop and report on the multithermal analysis of the combined data set. The loop being analyzed is visible in the 94, 131, 171, 193, 211, 335 Å passbands on AIA; and the Al-thick, Ti-poly, Al-mesh, Al-poly/Ti-poly, C-Poly/Ti-poly, C-poly, Be-thin, Be-med, Al-med, and Al-poly filters on XRT. Solar physics research at the University of Memphis is supported by NSF ATM-0402729 as well as a Hinode subcontract from NASA/SAO.

  6. High energy neutrinos from primary cosmic rays accelerated in the cores of active galaxies

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Done, C.; Salamon, M. H.; Sommers, P.

    1991-01-01

    The spectra and high-energy neutrino fluxes are calculated from photomeson production in active galactic nuclei (AGN) such as quasars and Seyfert galaxies using recent UV and X-ray observations to define the photon fields and an accretion-disk shock-acceleration model for producing ultrahigh-energy cosmic rays in the AGN. Collectively AGN should produce the dominant isotropic neutrino background between 10 exp 4 and 10 exp 10 GeV. Measurement of this background could be critical in determining the energy-generation mechanism, evolution, and distribution of AGN. High-energy background spectra and spectra from bright AGN such as NGC4151 and 3C273 are predicted which should be observable with present detectors. High energy AGN nus should produce a sphere of stellar disruption around their cores which could explain their observed broad-line emission regions.

  7. Redox-Active Sensing by Bacterial DksA Transcription Factors Is Determined by Cysteine and Zinc Content

    PubMed Central

    Crawford, Matthew A.; Tapscott, Timothy; Fitzsimmons, Liam F.; Liu, Lin; Reyes, Aníbal M.; Libby, Stephen J.; Trujillo, Madia; Fang, Ferric C.; Radi, Rafael

    2016-01-01

    ABSTRACT The four-cysteine zinc finger motif of the bacterial RNA polymerase regulator DksA is essential for protein structure, canonical control of the stringent response to nutritional limitation, and thiol-based sensing of oxidative and nitrosative stress. This interdependent relationship has limited our understanding of DksA-mediated functions in bacterial pathogenesis. Here, we have addressed this challenge by complementing ΔdksA Salmonella with Pseudomonas aeruginosa dksA paralogues that encode proteins differing in cysteine and zinc content. We find that four-cysteine, zinc-bound (C4) and two-cysteine, zinc-free (C2) DksA proteins are able to mediate appropriate stringent control in Salmonella and that thiol-based sensing of reactive species is conserved among C2 and C4 orthologues. However, variations in cysteine and zinc content determine the threshold at which individual DksA proteins sense and respond to reactive species. In particular, zinc acts as an antioxidant, dampening cysteine reactivity and raising the threshold of posttranslational thiol modification with reactive species. Consequently, C2 DksA triggers transcriptional responses in Salmonella at levels of oxidative or nitrosative stress normally tolerated by Salmonella expressing C4 orthologues. Inappropriate transcriptional regulation by C2 DksA increases the susceptibility of Salmonella to the antimicrobial effects of hydrogen peroxide and nitric oxide, and attenuates virulence in macrophages and mice. Our findings suggest that the redox-active sensory function of DksA proteins is finely tuned to optimize bacterial fitness according to the levels of oxidative and nitrosative stress encountered by bacterial species in their natural and host environments. PMID:27094335

  8. Activities for Challenging Gifted Learners by Increasing Complexity in the Common Core

    ERIC Educational Resources Information Center

    McKeone, Alyssa; Caruso, Lenora; Bettle, Kailyn; Chase, Ashley; Bryson, Bridget; Schneider, Jean S.; Rule, Audrey C.

    2015-01-01

    Gifted learners need opportunities for critical and creative thinking to stretch their minds and imaginations. Strategies for increasing complexity in the four core areas of language arts, mathematics, science, and social studies were addressed using the Common Core and Iowa Core Standards through several methods. Descriptive adjective object…

  9. Dual 4- and 5-phosphatase activities regulate SopB-dependent phosphoinositide dynamics to promote bacterial entry.

    PubMed

    Piscatelli, Heather L; Li, Menghan; Zhou, Daoguo

    2016-05-01

    Salmonella are able to invade non-phagocytic cells such as intestinal epithelial cells by modulating the host actin cytoskeleton to produce membrane ruffles. Two type III effector proteins SopB and SopE play key roles to this modulation. SopE is a known guanine nucleotide exchange factor (GEF) capable of activating Rac1 and CDC42. SopB is a phosphatidylinositol 4-phosphatase and 5-phosphatase promoting membrane ruffles and invasion of Salmonella through undefined mechanisms. Previous studies have demonstrated that the 4-phosphatase activity of SopB is required for PtdIns-3-phosphate (PtdIns(3)P) accumulation and SopB-mediated invasion. We show here that both the 4-phosphatase as well as the 5-phosphatase activities of SopB are essential in ruffle formation and subsequent invasion. We found that the 5-phosphatase activity of SopB is likely responsible for generating PtdIns-3,4-bisphosphate (PtdIns(3,4)P2 ) and subsequent recruitment of sorting nexin 9 (SNX9), an actin modulating protein. Intriguingly, the 4-phosphatase activity is responsible for the dephosphorylation of PtdIns(3,4)P2 into PtdIns(3)P. Alone, neither activity is sufficient for ruffling but when acting in conjunction with one another, the 4-phosphatase and 5-phosphatase activities led to SNX9-mediated ruffling and Salmonella invasion. This work reveals the unique ability of bacterial effector protein SopB to utilize both its 4- and 5-phosphatase activities to regulate phosphoinositide dynamics to promote bacterial entry. PMID:26537021

  10. Negative core affect and employee silence: How differences in activation, cognitive rumination, and problem-solving demands matter.

    PubMed

    Madrid, Hector P; Patterson, Malcolm G; Leiva, Pedro I

    2015-11-01

    Employees can help to improve organizational performance by sharing ideas, suggestions, or concerns about practices, but sometimes they keep silent because of the experience of negative affect. Drawing and expanding on this stream of research, this article builds a theoretical rationale based on core affect and cognitive appraisal theories to describe how differences in affect activation and boundary conditions associated with cognitive rumination and cognitive problem-solving demands can explain employee silence. Results of a diary study conducted with professionals from diverse organizations indicated that within-person low-activated negative core affect increased employee silence when, as an invariant factor, cognitive rumination was high. Furthermore, within-person high-activated negative core affect decreased employee silence when, as an invariant factor, cognitive problem-solving demand was high. Thus, organizations should manage conditions to reduce experiences of low-activated negative core affect because these feelings increase silence in individuals high in rumination. In turn, effective management of experiences of high-activated negative core affect can reduce silence for individuals working under high problem-solving demand situations. PMID:26011721

  11. Copper-Doped Inverted Core/Shell Nanocrystals with “Permanent” Optically Active Holes

    SciTech Connect

    Viswanatha, Ranjani; Brovelli, Sergio; Pandey, Anshu; Crooker, Scott A.; Klimov, Victor I.

    2011-09-23

    We have developed a new class of colloidal nanocrystals composed of Cu-doped ZnSe cores overcoated with CdSe shells. Via spectroscopic and magneto-optical studies, we conclusively demonstrate that Cu impurities represent paramagnetic +2 species and serve as a source of permanent optically active holes. This implies that the Fermi level is located below the Cu{sup 2+}/Cu{sup 1+} state, that is, in the lower half of the forbidden gap, which is a signature of a p-doped material. It further suggests that the activation of optical emission due to the Cu level requires injection of only an electron without a need for a valence-band hole. This peculiar electron-only emission mechanism is confirmed by experiments in which the titration of the nanocrystals with hole-withdrawing molecules leads to enhancement of Cu-related photoluminescence while simultaneously suppressing the intrinsic, band-edge exciton emission. In addition to containing permanent optically active holes, these newly developed materials show unprecedented emission tunability from near-infrared (1.2 eV) to the blue (3.1 eV) and reduced losses from reabsorption due to a large Stokes shift (up to 0.7 eV). These properties make them very attractive for applications in light-emission and lasing technologies and especially for the realization of novel device concepts such as “zero-threshold” optical gain.

  12. Nucleus accumbens core acetylcholine is preferentially activated during acquisition of drug- vs food-reinforced behavior.

    PubMed

    Crespo, Jose A; Stöckl, Petra; Zorn, Katja; Saria, Alois; Zernig, Gerald

    2008-12-01

    Acquisition of drug-reinforced behavior is accompanied by a systematic increase of release of the neurotransmitter acetylcholine (ACh) rather than dopamine, the expected prime reward neurotransmitter candidate, in the nucleus accumbens core (AcbC), with activation of both muscarinic and nicotinic ACh receptors in the AcbC by ACh volume transmission being necessary for the drug conditioning. The present findings suggest that the AcbC ACh system is preferentially activated by drug reinforcers, because (1) acquisition of food-reinforced behavior was not paralleled by activation of ACh release in the AcbC whereas acquisition of morphine-reinforced behavior, like that of cocaine or remifentanil (tested previously), was, and because (2) local intra-AcbC administration of muscarinic or nicotinic ACh receptor antagonists (atropine or mecamylamine, respectively) did not block the acquisition of food-reinforced behavior whereas acquisition of drug-reinforced behavior had been blocked. Interestingly, the speed with which a drug of abuse distributed into the AcbC and was eliminated from the AcbC determined the size of the AcbC ACh signal, with the temporally more sharply delineated drug stimulus producing a more pronounced AcbC ACh signal. The present findings suggest that muscarinic and nicotinic ACh receptors in the AcbC are preferentially involved during reward conditioning for drugs of abuse vs sweetened condensed milk as a food reinforcer. PMID:18418362

  13. Structure-activity relationship of lipid core peptide-based Group A Streptococcus vaccine candidates.

    PubMed

    Chan, Amy; Hussein, Waleed M; Ghaffar, Khairunnisa Abdul; Marasini, Nirmal; Mostafa, Ahmed; Eskandari, Sharareh; Batzloff, Michael R; Good, Michael F; Skwarczynski, Mariusz; Toth, Istvan

    2016-07-15

    Infection with Group A Streptococcus (GAS) can result in a range of different illnesses, some of which are fatal. Currently, our efforts to develop a vaccine against GAS focuses on the lipid core peptide (LCP) system, a subunit vaccine containing a lipoamino acid (LAA) moiety which allows the stimulation of systemic antibody activity. In the present study, a peptide (J14) representing the B-cell epitope from the GAS M protein was incorporated alongside a universal T-helper epitope (P25) in four LCP constructs of different spatial orientation or LAA lengths. Through structure-activity studies, it was discovered that while the alteration of the LCP orientation had a weaker effect on immunostimulation, increasing the LAA side chain length within the construct increased antibody responses in murine models. Furthermore, the mice immunised with the lead LCP construct were also able to maintain antibody activity throughout the course of five months. These findings highlight the importance of LAA moieties in the development of intranasal peptide vaccines and confirmed that its side chain length has an effect on the immunogenicity of the structure. PMID:27246859

  14. Crystal Structure of a Bacterial Type IB DNA Topoisomerase Reveals a Preassembled Active Site in the Absence of DNA

    SciTech Connect

    Patel, Asmita; Shuman, Stewart; Mondragon, Alfonso

    2010-03-08

    Type IB DNA topoisomerases are found in all eukarya, two families of eukaryotic viruses (poxviruses and mimivirus), and many genera of bacteria. They alter DNA topology by cleaving and resealing one strand of duplex DNA via a covalent DNA-(3-phosphotyrosyl)-enzyme intermediate. Bacterial type IB enzymes were discovered recently and are described as poxvirus-like with respect to their small size, primary structures, and bipartite domain organization. Here we report the 1.75-{angstrom} crystal structure of Deinococcus radiodurans topoisomerase IB (DraTopIB), a prototype of the bacterial clade. DraTopIB consists of an amino-terminal (N) {beta}-sheet domain (amino acids 1-90) and a predominantly {alpha}-helical carboxyl-terminal (C) domain (amino acids 91-346) that closely resemble the corresponding domains of vaccinia virus topoisomerase IB. The five amino acids of DraTopIB that comprise the catalytic pentad (Arg-137, Lys-174, Arg-239, Asn-280, and Tyr-289) are preassembled into the active site in the absence of DNA in a manner nearly identical to the pentad configuration in human topoisomerase I bound to DNA. This contrasts with the apoenzyme of vaccinia topoisomerase, in which three of the active site constituents are either displaced or disordered. The N and C domains of DraTopIB are splayed apart in an 'open' conformation, in which the surface of the catalytic domain containing the active site is exposed for DNA binding. A comparison with the human topoisomerase I-DNA cocrystal structure suggests how viral and bacterial topoisomerase IB enzymes might bind DNA circumferentially via movement of the N domain into the major groove and clamping of a disordered loop of the C domain around the helix.

  15. Inhibitory activity of cranberry extract on the bacterial adhesiveness in the urine of women: an ex-vivo study.

    PubMed

    Tempera, G; Corsello, S; Genovese, C; Caruso, F E; Nicolosi, D

    2010-01-01

    Strains of uropathogenic E. coli are responsible for approximately 90% of community-acquired, uncomplicated cystitis, and fimbriae represent the adhesive factors enabling E. coli to be anchored to uroepithelial cells in the first step of the infectious process. Recently, a few studies have shown that a correlation between the consumption of cranberry (Vaccinium macrocarpon) and prevention of UTI is related to the ability of proanthocyanidins to reduce the bacterial adhesion to uroepithelial cells. In this study we evaluate the inhibitory activity of urine of healthy women treated with tablets containing cranberry extract on the adhesiveness of E. coli to uroepithelial human cells. Two groups of 12 female volunteers each, aged between 18 and 65 years, were enrolled, one group with negative history and one group with positive history of recurrent cystitis. Subjects were treated with the active product or placebo in a random, cross-over, double-blinded sequence for one week in each of the two treatment sequences. Urine samples were collected at the beginning and the end of each study period. Tests of bacterial adhesiveness were performed with two strains of E. coli (ATCC 25922 and ATCC 35218) on HT1376 human bladder carcinoma cells. Significant reductions of bacterial adhesiveness were observed in women who received cranberry extract (-50.9%; p less than 0.0001), regardless of their medical history and the treatment period in the cross-over sequence. No changes were observed with placebo (-0.29%; n.s.). This ex-vivo study showed that the assumption of cranberry extract in suitable amounts can have an anti-adhesive activity on uropathogenic E. coli. PMID:20646356

  16. Inhibition of reverse transcriptase activity increases stability of the HIV-1 core.

    PubMed

    Yang, Yang; Fricke, Thomas; Diaz-Griffero, Felipe

    2013-01-01

    Previous studies showed that HIV-1 reverse transcription occurs during or before uncoating, linking mechanistically reverse transcription with uncoating. Here we show that inhibition of reverse transcriptase (RT) during HIV-1 infection by pharmacologic or genetic means increased the stability of the HIV-1 core during infection. Interestingly, HIV-1 particles with increased core stability were resistant to the core-destabilizing effects of rhesus TRIM5α (TRIM5α(rh)). Collectively, this work implies that the surface of the HIV-1 core is dynamic and changes upon the ongoing processes within the core. PMID:23077298

  17. Addition of Selenium Nanoparticles to Electrospun Silk Scaffold Improves the Mammalian Cell Activity While Reducing Bacterial Growth

    PubMed Central

    Chung, Stanley; Ercan, Batur; Roy, Amit K.; Webster, Thomas J.

    2016-01-01

    Silk possesses many beneficial wound healing properties, and electrospun scaffolds are especially applicable for skin applications, due to their smaller interstices and higher surface areas. However, purified silk promotes microbial growth. Selenium nanoparticles have shown excellent antibacterial properties and are a novel antimicrobial chemistry. Here, electrospun silk scaffolds were doped with selenium nanoparticles to impart antibacterial properties to the silk scaffolds. Results showed significantly improved bacterial inhibition and mild improvement in human dermal fibroblast metabolic activity. These results suggest that the addition of selenium nanoparticles to electrospun silk is a promising approach to improve wound healing with reduced infection, without relying on antibiotics. PMID:27471473

  18. Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice.

    PubMed

    Shrestha, Bishnu K; Karki, Hari Sharan; Groth, Donald E; Jungkhun, Nootjarin; Ham, Jong Hyun

    2016-01-01

    Potential biological control agents for two major rice diseases, sheath blight and bacterial panicle blight, were isolated from rice plants in this study. Rice-associated bacteria (RABs) isolated from rice plants grown in the field were tested for their antagonistic activities against the rice pathogens, Rhizoctonia solani and Burkholderia glumae, which cause sheath blight and bacterial panicle blight, respectively. Twenty-nine RABs were initially screened based on their antagonistic activities against both R. solani and B. glumae. In follow-up retests, 26 RABs of the 29 RABs were confirmed to have antimicrobial activities, but the rest three RABs did not reproduce any observable antagonistic activity against R. solani or B. glumae. According to16S rDNA sequence identity, 12 of the 26 antagonistic RABs were closest to Bacillus amyloliquefaciens, while seven RABs were to B. methylotrophicus and B, subtilis, respectively. The 16S rDNA sequences of the three non-antagonistic RABs were closest to Lysinibacillus sphaericus (RAB1 and RAB12) and Lysinibacillus macroides (RAB5). The five selected RABs showing highest antimicrobial activities (RAB6, RAB9, RAB16, RAB17S, and RAB18) were closest to B. amyloliquefaciens in DNA sequence of 16S rDNA and gyrB, but to B. subtilis in that of recA. These RABs were observed to inhibit the sclerotial germination of R. solani on potato dextrose agar and the lesion development on detached rice leaves by artificial inoculation of R. solani. These antagonistic RABs also significantly suppressed the disease development of sheath blight and bacterial panicle blight in a field condition, suggesting that they can be potential biological control agents for these rice diseases. However, these antagonistic RABs showed diminished disease suppression activities in the repeated field trial conducted in the following year probably due to their reduced antagonistic activities to the pathogens during the long-term storage in -70C, suggesting that

  19. Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice

    PubMed Central

    Shrestha, Bishnu K.; Karki, Hari Sharan; Groth, Donald E.; Jungkhun, Nootjarin; Ham, Jong Hyun

    2016-01-01

    Potential biological control agents for two major rice diseases, sheath blight and bacterial panicle blight, were isolated from rice plants in this study. Rice-associated bacteria (RABs) isolated from rice plants grown in the field were tested for their antagonistic activities against the rice pathogens, Rhizoctonia solani and Burkholderia glumae, which cause sheath blight and bacterial panicle blight, respectively. Twenty-nine RABs were initially screened based on their antagonistic activities against both R. solani and B. glumae. In follow-up retests, 26 RABs of the 29 RABs were confirmed to have antimicrobial activities, but the rest three RABs did not reproduce any observable antagonistic activity against R. solani or B. glumae. According to16S rDNA sequence identity, 12 of the 26 antagonistic RABs were closest to Bacillus amyloliquefaciens, while seven RABs were to B. methylotrophicus and B, subtilis, respectively. The 16S rDNA sequences of the three non-antagonistic RABs were closest to Lysinibacillus sphaericus (RAB1 and RAB12) and Lysinibacillus macroides (RAB5). The five selected RABs showing highest antimicrobial activities (RAB6, RAB9, RAB16, RAB17S, and RAB18) were closest to B. amyloliquefaciens in DNA sequence of 16S rDNA and gyrB, but to B. subtilis in that of recA. These RABs were observed to inhibit the sclerotial germination of R. solani on potato dextrose agar and the lesion development on detached rice leaves by artificial inoculation of R. solani. These antagonistic RABs also significantly suppressed the disease development of sheath blight and bacterial panicle blight in a field condition, suggesting that they can be potential biological control agents for these rice diseases. However, these antagonistic RABs showed diminished disease suppression activities in the repeated field trial conducted in the following year probably due to their reduced antagonistic activities to the pathogens during the long-term storage in -70C, suggesting that

  20. Brainstem metabotropic glutamate receptors reduce food intake and activate dorsal pontine and medullar structures after peripheral bacterial lipopolysaccharide administration.

    PubMed

    Chaskiel, Léa; Paul, Flora; Gerstberger, Rüdiger; Hübschle, Thomas; Konsman, Jan Pieter

    2016-08-01

    During infection-induced inflammation food intake is reduced. Vagal and brainstem pathways are important both in feeding regulation and immune-to-brain communication. Glutamate is released by vagal afferent terminals in the nucleus of the solitary tract and by its neurons projecting to the parabrachial nuclei. We therefore studied the role of brainstem glutamate receptors in spontaneous food intake of healthy animals and during sickness-associated hypophagia after peripheral administration of bacterial lipopolysaccharides or interleukin-1beta. Brainstem group I and II metabotropic, but not ionotropic, glutamate receptor antagonism increased food intake both in saline- and lipopolysaccharide-treated rats. In these animals, expression of the cellular activation marker c-Fos in the lateral parabrachial nuclei and lipopolysaccharide-induced activation of the nucleus of the solitary tract rostral to the area postrema were suppressed. Group I metabotropic glutamate receptors did not colocalize with c-Fos or neurons regulating gastric function in these structures. Group I metabotropic glutamate receptors were, however, found on raphé magnus neurons that were part of the brainstem circuit innervating the stomach and on trigeminal and hypoglossal motor neurons. In conclusion, our findings show that brainstem metabotropic glutamate receptors reduce food intake and activate the lateral parabrachial nuclei as well as the rostral nucleus of the solitary tract after peripheral bacterial lipopolysaccharide administration. They also provide insight into potential group I metabotropic glutamate receptor-dependent brainstem circuits mediating these effects. PMID:27016016

  1. The Impact of Injections of Different Nutrients on the Bacterial Community and Its Dechlorination Activity in Chloroethene-Contaminated Groundwater

    PubMed Central

    Miura, Takamasa; Yamazoe, Atsushi; Ito, Masako; Ohji, Shoko; Hosoyama, Akira; Takahata, Yoh; Fujita, Nobuyuki

    2015-01-01

    Dehalococcoides spp. are currently the only organisms known to completely reduce cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) to non-toxic ethene. However, the activation of fermenting bacteria that generate acetate, hydrogen, and CO2 is considered necessary to enhance the dechlorination activity of Dehalococcoides and enable the complete dechlorination of chloroethenes. In the present study, we stimulated chloroethene-contaminated groundwater by injecting different nutrients prepared from yeast extract or polylactate ester using a semicontinuous culture system. We then evaluated changes in the bacterial community structure and their relationship with dechlorination activity during the biostimulation. The populations of Dehalococcoides and the phyla Bacteroidetes, Firmicutes, and Spirochaetes increased in the yeast extract-amended cultures and chloroethenes were completely dechlorinated. However, the phylum Proteobacteria was dominant in polylactate ester-amended cultures, in which almost no cis-DCE and VC were dechlorinated. These results provide fundamental information regarding possible interactions among bacterial community members involved in the dechlorination process and support the design of successful biostimulation strategies. PMID:25877696

  2. Tailor-made Au@Ag core-shell nanoparticle 2D arrays on protein-coated graphene oxide with assembly enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Wang, Huiqiao; Liu, Jinbin; Wu, Xuan; Tong, Zhonghua; Deng, Zhaoxiang

    2013-05-01

    Water-dispersible two-dimensional (2D) assemblies of Au@Ag core-shell nanoparticles are obtained through a highly selective electroless silver deposition on pre-assembled gold nanoparticles on bovine serum albumin (BSA)-coated graphene oxide (BSA-GO). While neither BSA-GO nor AuNP-decorated BSA-GO shows any antibacterial ability, the silver-coated GO@Au nanosheets (namely GO@Au@Ag) exhibit an enhanced antibacterial activity against Gram-negative Escherichia coli (E. coli) bacteria, superior to unassembled Au@Ag nanoparticles and even ionic Ag. Such an improvement may be attributed to the increased local concentration of silver nanoparticles around a bacterium and a polyvalent interaction with the bacterial surface. In addition, the colloidal stability of this novel nano-antimicrobial against the formation of random nanoparticle aggregates guarantees a minimized activity loss of the Au@Ag nanoparticles. The antibacterial efficacy of GO@Au@Ag is less sensitive to the existence of Cl-, in comparison with silver ions, providing another advantage for wound dressing applications. Our research unambiguously reveals a strong and very specific interaction between the GO@Au@Ag nanoassembly and E. coli, which could be an important clue toward a rational design, synthesis and assembly of innovative and highly active antibacterial nanomaterials.

  3. The effects of core muscle activation on dynamic trunk position and knee abduction moments: implications for ACL injury.

    PubMed

    Jamison, Steve T; McNally, Michael P; Schmitt, Laura C; Chaudhari, Ajit M W

    2013-09-01

    Anterior cruciate ligament (ACL) injury is one of the most common serious lower-extremity injuries experienced by athletes participating in field and court sports and often occurs during a sudden change in direction or pivot. Both lateral trunk positioning during cutting and peak external knee abduction moments have been associated with ACL injury risk, though it is not known how core muscle activation influences these variables. In this study, the association between core muscle pre-activation and trunk position as well as the association between core muscle pre-activation and peak knee abduction moment during an unanticipated run-to-cut maneuver were investigated in 46 uninjured individuals. Average co-contraction indices and percent differences between muscle pairs were calculated prior to initial contact for internal obliques, external obliques, and L5 extensors using surface electromyography. Outside tilt of the trunk was defined as positive when the trunk was angled away from the cutting direction. No significant associations were found between pre-activations of core muscles and outside tilt of the trunk. Greater average co-contraction index of the L5 extensors was associated with greater peak knee abduction moment (p=0.0107). Increased co-contraction of the L5 extensors before foot contact could influence peak knee abduction moment by stiffening the spine, limiting sagittal plane trunk flexion (a motion pattern previously linked to ACL injury risk) and upper body kinetic energy absorption by the core during weight acceptance. PMID:23891313

  4. Effect of transportation on fecal bacterial communities and fermentative activities in horses: impact of Saccharomyces cerevisiae CNCM I-1077 supplementation.

    PubMed

    Faubladier, C; Chaucheyras-Durand, F; da Veiga, L; Julliand, V

    2013-04-01

    This study evaluated the effect of transportation on fecal bacterial communities and activities in horses with or without supplementation of live yeast and attempted to link those effects with changes in blood stress markers. Four mature horses were assigned to a crossover design and fed a basal diet (60:40 forage to concentrate; 1.45% BW on a DM basis), with or without supplementation, of 2 × 10(10) cfu/d of Saccharomyces cerevisiae CNCM I-1077. After a 14-d adaptation to dietary treatments, the 5-d experiment started 1 d before transportation (d -1). At d 0, horses were simultaneously transported in a truck for 2 h. Feces were sampled 4 h after the morning meal of concentrate at d -1, 0 (immediately after transportation), and 3 for enumeration of the main functional bacterial groups and determination of fermentative variables. Within each dietary treatment, feces were pooled before DNA extraction and molecular analysis of the bacterial communities, using temporal temperature gradient electrophoreses (TTGE). Blood samples were collected at the same time for determination of white blood cells (WBC) counts and glucose and total protein concentrations. Regardless of dietary treatment, the neutrophil to lymphocyte ratio increased during transportation (P < 0.01), indicating that horses were stressed. In both treatments, TTGE profiles were clearly different before and 3 d after transportation, and the percentage of similarity between profiles at d -1 and 3 was greater in supplemented horses compared with the controls. From d 0 to 3, the molar percentage of propionate increased and total concentration of VFA and the acetate + butyrate to propionate ratio decreased, regardless of dietary treatment (P < 0.01, P = 0.02, and P < 0.01, respectively), whereas pH decreased only in control horses (P = 0.03). Regardless of day of sampling, fecal concentrations of lactate-utilizing bacteria and cellulolytic bacteria were greater in supplemented horses than in control horses (P

  5. Modeling active galactic nucleus feedback in cool-core clusters: The balance between heating and cooling

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-01

    We study the long-term evolution of an idealized cool-core galaxy cluster under the influence of momentum-driven active galactic nucleus (AGN) feedback using three-dimensional high-resolution (60 pc) adaptive mesh refinement simulations. The feedback is modeled with a pair of precessing jets whose power is calculated based on the accretion rate of the cold gas surrounding the supermassive black hole (SMBH). The intracluster medium first cools into clumps along the propagation direction of the jets. As the jet power increases, gas condensation occurs isotropically, forming spatially extended structures that resemble the observed Hα filaments in Perseus and many other cool-core clusters. Jet heating elevates the gas entropy, halting clump formation. The cold gas that is not accreted onto the SMBH settles into a rotating disk of ∼10{sup 11} M {sub ☉}. The hot gas cools directly onto the disk while the SMBH accretes from its innermost region, powering the AGN that maintains a thermally balanced state for a few Gyr. The mass cooling rate averaged over 7 Gyr is ∼30 M {sub ☉} yr{sup –1}, an order of magnitude lower than the classic cooling flow value. Medium resolution simulations produce similar results, while in low resolution runs, the cluster experiences cycles of gas condensation and AGN outbursts. Owing to its self-regulating mechanism, AGN feedback can successfully balance cooling with a wide range of model parameters. Our model also produces cold structures in early stages that are in good agreement with the observations. However, the long-lived massive cold disk is unrealistic, suggesting that additional physical processes are still needed.

  6. Preparation and photocatalytic activity of eccentric Au-titania core-shell nanoparticles by block copolymer templates.

    PubMed

    Li, Xue; Fu, Xiaoning; Yang, Hui

    2011-02-21

    A novel route for a preparation of eccentric Au-titania core-shell nanoparticles using gold nanoparticles (AuNPs) with block copolymer shells as a template is reported. AuNPs with poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) block copolymer shells are first prepared by UV irradiation of the solution of PVP-b-PEO/HAuCl(4) complexes. Then the sol-gel reaction of titanium tetra-isopropoxide (TTIP) selectively on the surfaces of AuNPs leads to Au-titania core-shell composite nanoparticles. The eccentric Au-titania core-shell nanoparticles are obtained from the Au-titania core-shell composite nanoparticles by removal of organic interlayer by UV treatment. Photocatalytic activities of the resulting eccentric core-shell nanoparticles are investigated in terms of the degradation of methylene blue (MB). The results show that the eccentric core-shell structures endow the catalyst with greatly enhanced photocatalytic activity. PMID:21157597

  7. Contrasting activity patterns determined by BrdU incorporation in bacterial ribotypes from the Arctic Ocean in winter

    PubMed Central

    Galand, Pierre E.; Alonso-Sáez, Laura; Bertilsson, Stefan; Lovejoy, Connie; Casamayor, Emilio O.

    2013-01-01

    The winter Arctic Ocean is one of the most unexplored marine environments from a microbiological perspective. Heterotrophic bacteria maintain their activity at a baseline level during the extremely low-energy conditions of the winter, but little is known about the specific phylotypes that have the potential to survive and grow in such harsh environment. In this study, we aimed at identifying actively growing ribotypes in winter Arctic Ocean seawater cultures by experimental incubations with the thymidine analog bromodeoxyuridine (BrdU), followed by immunocapturing, terminal restriction fragment length polymorphism fingerprinting, cloning, and sequencing the 16S rRNA gene. We incubated water collected at different months over the Arctic winter and showed that the actively growing bacterial fraction, taking up BrdU, represented only a subset of the total community. Among the BrdU-labeled bacterial taxa we identified the Flavobacteria Polaribacter, the Alphaproteobacteria SAR11, the Gammaproteobacteria Arctic 96B-16 cluster and, predominately, members of Colwellia spp. Interestingly, Colwellia sequences formed three clusters (93 and 97% pairwise 16S rRNA identity) that contributed in contrasting ways to the active communities in the incubations. Polaribacter, Arctic 96B-16 and one cluster of Colwellia were more abundant in the active community represented by the BrdU-labeled DNA. In contrast, SAR11 and two other Colwellia clusters were underrepresented in the BrdU-labeled community compared to total communities. Despite the limitation of the long incubations needed to label slow growing arctic communities, the BrdU approach revealed the potential for active growth in low-energy conditions in some relevant groups of polar bacteria, including Polaribacter and Arctic 96B-16. Moreover, under similar incubation conditions, the growth of different Colwellia ribotypes varied, suggesting that related clusters of Colwellia may have distinct metabolic features. PMID:23750155

  8. Contrasting activity patterns determined by BrdU incorporation in bacterial ribotypes from the Arctic Ocean in winter.

    PubMed

    Galand, Pierre E; Alonso-Sáez, Laura; Bertilsson, Stefan; Lovejoy, Connie; Casamayor, Emilio O

    2013-01-01

    The winter Arctic Ocean is one of the most unexplored marine environments from a microbiological perspective. Heterotrophic bacteria maintain their activity at a baseline level during the extremely low-energy conditions of the winter, but little is known about the specific phylotypes that have the potential to survive and grow in such harsh environment. In this study, we aimed at identifying actively growing ribotypes in winter Arctic Ocean seawater cultures by experimental incubations with the thymidine analog bromodeoxyuridine (BrdU), followed by immunocapturing, terminal restriction fragment length polymorphism fingerprinting, cloning, and sequencing the 16S rRNA gene. We incubated water collected at different months over the Arctic winter and showed that the actively growing bacterial fraction, taking up BrdU, represented only a subset of the total community. Among the BrdU-labeled bacterial taxa we identified the Flavobacteria Polaribacter, the Alphaproteobacteria SAR11, the Gammaproteobacteria Arctic 96B-16 cluster and, predominately, members of Colwellia spp. Interestingly, Colwellia sequences formed three clusters (93 and 97% pairwise 16S rRNA identity) that contributed in contrasting ways to the active communities in the incubations. Polaribacter, Arctic 96B-16 and one cluster of Colwellia were more abundant in the active community represented by the BrdU-labeled DNA. In contrast, SAR11 and two other Colwellia clusters were underrepresented in the BrdU-labeled community compared to total communities. Despite the limitation of the long incubations needed to label slow growing arctic communities, the BrdU approach revealed the potential for active growth in low-energy conditions in some relevant groups of polar bacteria, including Polaribacter and Arctic 96B-16. Moreover, under similar incubation conditions, the growth of different Colwellia ribotypes varied, suggesting that related clusters of Colwellia may have distinct metabolic features. PMID:23750155

  9. Inhibitory activity of Salvadora persica extracts against oral bacterial strains associated with periodontitis: An in-vitro study

    PubMed Central

    Amir Alireza, Rasouli Ghahroudi; Afsaneh, Rezaei; Seied Hosein, Mohseni Salehifard; Siamak, Yaghoobee; Afshin, Khorsand; Zeinab, Kadkhoda; Mahvash, Moosavi Jazi; Amir Reza, Rokn

    2014-01-01

    Aims The use of natural plant extracts in pharmacology, medicine and dental hygiene has found a growing interest in modern scientific research. Salvadora persica is a natural tree whose fibrous branches have been approved by the World Health Organization for oral hygiene. Periodontitis is a highly prevalent adult gingival disease that leads to bone destruction and connective tissue attachment loss. The aim of this research was assessment the antimicrobial activities of methanolic extract of Salvadora persica (miswak) on isolated strains from the oral fluid. Methods In practical section, 50 female university students (21.4 ± 1 year) participated in the study. Based on examination by a periodontist, they were grouped into (Group I, n = 21) and (Group II, n = 29) i.e. with and without periodontitis respectively. Their un-stimulated saliva samples were obtained in sterile tubes. While three bacterial genera, Staphylococcus, Streptococcus and Lactobacillus were identified in all subjects, Enterococcus and Escherichia were only detected in Group I. Results A statistically significant difference in colonization levels between the two groups was observed. The effect of methanolic extract of S. persica against oral bacterial strains isolated from saliva was investigated using agar disc diffusion and microdilution methods. Although methanolic extract of S. persica was effective on growth inhibition of all strains, it was significantly more effective on Gram positive bacteria than Gram negative ones. Conclusions Effective substances present in S. persica extracts, exhibit a broad range of antibacterial activity and affect almost all bacterial species regardless of the Gram-staining nature. PMID:25737914

  10. Chemical Composition, Modulatory Bacterial Resistance and Antimicrobial Activity of Essential Oil the Hyptis martiusii Benth by Direct and Gaseous Contact

    PubMed Central

    de Oliveira, Allan Demetrius Leite; Galvao Rodrigue, Fabiola Fernandes; Douglas Melo Coutinho, Henrique; da Costa, Jose Galberto Martins; de Menezes, Irwin Rose Alencar

    2014-01-01

    Background: Several studies have shown that species of the genus Hyptis, have promising antimicrobial and antifungal effects. Objectives: Identify of chemical constituents of essential oil from leaves of Hyptis martiusii and evaluate its effect against bacterial strains by direct and gaseous contact. Materials and Methods: Essential oil was extracted from leaves of Hyptis martiusii Benth using hydro-distillation, and its composition was determined using gas chromatography–mass spectrometry (GC-MS). Chemical analysis showed that there was a predominance of sesquiterpenes. The leaf essential oil was screened for its minimal inhibitory concentration and modulatory effect of aminoglycoside by the direct (MIC) and gaseous (MID) micro-dilution assays for various pathogenic microorganisms. The essential oil remarkably inhibited the growth of all of the tested bacteria (MIC < 512 μg/mL) except S. aureus (SA358) multidrug resistant (MRSA) by direct contact. Results: Twenty-four compounds representing 92.13% of the essential oil of leaves were characterized; δ -3-carene (6.88%), 1, 8-cineole (7.01%), trans-caryophyllene (9.21%), Cariophyllene oxide (7.47%) and bicyclogermacrene (10.61%) were found as the major components. Modulatory aminoglycoside effect, by direct contact, was showed antagonistic relationship with antimicrobial activity. The gaseous component of the oil inhibited the bacterial growth of all of the tested bacteria in 50% and 25% of oil concentration and demonstrated synergistic interactions can be attributed to the constituting the oil compounds. Conclusions: These results show that this oil influences the activity of the antibiotic and may be used as an adjuvant in the antibiotic therapy of respiratory tract bacterial pathogens. PMID:25237640

  11. USING A DIFFERENTIAL EMISSION MEASURE AND DENSITY MEASUREMENTS IN AN ACTIVE REGION CORE TO TEST A STEADY HEATING MODEL

    SciTech Connect

    Winebarger, Amy R.; Schmelz, Joan T.; Warren, Harry P.; Saar, Steve H.; Kashyap, Vinay L.

    2011-10-10

    The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that heating events occur rapidly enough to keep high-temperature active region loops close to equilibrium. In this paper, we couple observations of active region (AR) 10955 made with the X-Ray Telescope and the EUV Imaging Spectrometer on board Hinode to test a simple steady heating model. First we calculate the differential emission measure (DEM) of the apex region of the loops in the active region core. We find the DEM to be broad and peaked around 3 MK. We then determine the densities in the corresponding footpoint regions. Using potential field extrapolations to approximate the loop lengths and the density-sensitive line ratios to infer the magnitude of the heating, we build a steady heating model for the active region core and find that we can match the general properties of the observed DEM for the temperature range of 6.3 < log T < 6.7. This model, for the first time, accounts for the base pressure, loop length, and distribution of apex temperatures of the core loops. We find that the density-sensitive spectral line intensities and the bulk of the hot emission in the active region core are consistent with steady heating. We also find, however, that the steady heating model cannot address the emission observed at lower temperatures. This emission may be due to foreground or background structures, or may indicate that the heating in the core is more complicated. Different heating scenarios must be tested to determine if they have the same level of agreement.

  12. Core-shell nanocarriers with high paclitaxel loading for passive and active targeting

    NASA Astrophysics Data System (ADS)

    Jin, Zhu; Lv, Yaqi; Cao, Hui; Yao, Jing; Zhou, Jianping; He, Wei; Yin, Lifang

    2016-06-01

    Rapid blood clearance and premature burst release are inherent drawbacks of conventional nanoparticles, resulting in poor tumor selectivity. iRGD peptide is widely recognized as an efficient cell membrane penetration peptide homing to αVβ3 integrins. Herein, core-shell nanocapsules (NCs) and iRGD-modified NCs (iRGD-NCs) with high drug payload for paclitaxel (PTX) were prepared to enhance the antitumor activities of chemotherapy agents with poor water solubility. Improved in vitro and in vivo tumor targeting and penetration were observed with NCs and iRGD-NCs; the latter exhibited better antitumor activity because iRGD enhanced the accumulation and penetration of NCs in tumors. The NCs were cytocompatible, histocompatible, and non-toxic to other healthy tissues. The endocytosis of NCs was mediated by lipid rafts in an energy-dependent manner, leading to better cytotoxicity of PTX against cancer cells. In contrast with commercial product, PTX-loaded NCs (PTX-NCs) increased area under concentration-time curve (AUC) by about 4-fold, prolonged mean resident time (MRT) by more than 8-fold and reduced the elimination rate constant by greater than 68-fold. In conclusion, the present nanocarriers with high drug-loading capacity represent an efficient tumor-targeting drug delivery system with promising potential for cancer therapy.

  13. Core-shell nanocarriers with high paclitaxel loading for passive and active targeting

    PubMed Central

    Jin, Zhu; Lv, Yaqi; Cao, Hui; Yao, Jing; Zhou, Jianping; He, Wei; Yin, Lifang

    2016-01-01

    Rapid blood clearance and premature burst release are inherent drawbacks of conventional nanoparticles, resulting in poor tumor selectivity. iRGD peptide is widely recognized as an efficient cell membrane penetration peptide homing to αVβ3 integrins. Herein, core-shell nanocapsules (NCs) and iRGD-modified NCs (iRGD-NCs) with high drug payload for paclitaxel (PTX) were prepared to enhance the antitumor activities of chemotherapy agents with poor water solubility. Improved in vitro and in vivo tumor targeting and penetration were observed with NCs and iRGD-NCs; the latter exhibited better antitumor activity because iRGD enhanced the accumulation and penetration of NCs in tumors. The NCs were cytocompatible, histocompatible, and non-toxic to other healthy tissues. The endocytosis of NCs was mediated by lipid rafts in an energy-dependent manner, leading to better cytotoxicity of PTX against cancer cells. In contrast with commercial product, PTX-loaded NCs (PTX-NCs) increased area under concentration-time curve (AUC) by about 4-fold, prolonged mean resident time (MRT) by more than 8-fold and reduced the elimination rate constant by greater than 68-fold. In conclusion, the present nanocarriers with high drug-loading capacity represent an efficient tumor-targeting drug delivery system with promising potential for cancer therapy. PMID:27278751

  14. Core-shell nanocarriers with high paclitaxel loading for passive and active targeting.

    PubMed

    Jin, Zhu; Lv, Yaqi; Cao, Hui; Yao, Jing; Zhou, Jianping; He, Wei; Yin, Lifang

    2016-01-01

    Rapid blood clearance and premature burst release are inherent drawbacks of conventional nanoparticles, resulting in poor tumor selectivity. iRGD peptide is widely recognized as an efficient cell membrane penetration peptide homing to αVβ3 integrins. Herein, core-shell nanocapsules (NCs) and iRGD-modified NCs (iRGD-NCs) with high drug payload for paclitaxel (PTX) were prepared to enhance the antitumor activities of chemotherapy agents with poor water solubility. Improved in vitro and in vivo tumor targeting and penetration were observed with NCs and iRGD-NCs; the latter exhibited better antitumor activity because iRGD enhanced the accumulation and penetration of NCs in tumors. The NCs were cytocompatible, histocompatible, and non-toxic to other healthy tissues. The endocytosis of NCs was mediated by lipid rafts in an energy-dependent manner, leading to better cytotoxicity of PTX against cancer cells. In contrast with commercial product, PTX-loaded NCs (PTX-NCs) increased area under concentration-time curve (AUC) by about 4-fold, prolonged mean resident time (MRT) by more than 8-fold and reduced the elimination rate constant by greater than 68-fold. In conclusion, the present nanocarriers with high drug-loading capacity represent an efficient tumor-targeting drug delivery system with promising potential for cancer therapy. PMID:27278751

  15. Viability and Effects on Bacterial Proteins by Oral Rinses with Hypochlorous Acid as Active Ingredient.

    PubMed

    Castillo, Diana Marcela; Castillo, Yormaris; Delgadillo, Nathaly Andrea; Neuta, Yineth; Jola, Johana; Calderón, Justo Leonardo; Lafaurie, Gloria Inés

    2015-10-01

    This study investigated the effect of hypochlorous acid (HOCl) rinses and chlorhexidine (CHX) on the bacterial viability of S. mutans, A. israelii, P. gingivalis, A. actinomycetemcomitans, E. corrodens, C. rectus, K. oxytoca, K. pneumoniae and E. cloacae. The percentage of live bacteria was tested by fluorescence method using Live/Dead kit(r) and BacLight (Molecular Probes(r)) and compared between groups by the Kruskal-Wallis and U Mann-Whitney tests with Bonferroni correction (p value<0.012). The effect of HOCl and CHX on total proteins of P. gingivalis and S. mutans was determined by SDS-PAGE. CHX showed a higher efficacy than HOCl against S. mutans, A. israelii, E. corrodens and E. cloacae (p<0.001) while HOCl was more effective than CHX against P. gingivalis, A. actinomycetemcomitans, C. rectus and K. oxytoca (p=0.001). CHX and HOCl had similar efficacy against K. pneumoniae. Proteins of P. gingivalis and S. mutans were affected similarly by HOCl and CHX. HOCl reduced the bacterial viability especially in periodontopathic bacteria, which may support its use in the control of subgingival biofilm in periodontal patients. PMID:26647939

  16. Acute Exposure to Crystalline Silica Reduces Macrophage Activation in Response to Bacterial Lipoproteins

    PubMed Central

    Beamer, Gillian L.; Seaver, Benjamin P.; Jessop, Forrest; Shepherd, David M.; Beamer, Celine A.

    2016-01-01

    Numerous studies have examined the relationship between alveolar macrophages (AMs) and crystalline silica (SiO2) using in vitro and in vivo immunotoxicity models; however, exactly how exposure to SiO2 alters the functionality of AM and the potential consequences for immunity to respiratory pathogens remains largely unknown. Because recognition and clearance of inhaled particulates and microbes are largely mediated by pattern recognition receptors (PRRs) on the surface of AM, we hypothesized that exposure to SiO2 limits the ability of AM to respond to bacterial challenge by altering PRR expression. Alveolar and bone marrow-derived macrophages downregulate TLR2 expression following acute SiO2 exposure (e.g., 4 h). Interestingly, these responses were dependent on interactions between SiO2 and the class A scavenger receptor CD204, but not MARCO. Furthermore, SiO2 exposure decreased uptake of fluorescently labeled Pam2CSK4 and Pam3CSK4, resulting in reduced secretion of IL-1β, but not IL-6. Collectively, our data suggest that SiO2 exposure alters AM phenotype, which in turn affects their ability to uptake and respond to bacterial lipoproteins. PMID:26913035

  17. Acute Exposure to Crystalline Silica Reduces Macrophage Activation in Response to Bacterial Lipoproteins.

    PubMed

    Beamer, Gillian L; Seaver, Benjamin P; Jessop, Forrest; Shepherd, David M; Beamer, Celine A

    2016-01-01

    Numerous studies have examined the relationship between alveolar macrophages (AMs) and crystalline silica (SiO2) using in vitro and in vivo immunotoxicity models; however, exactly how exposure to SiO2 alters the functionality of AM and the potential consequences for immunity to respiratory pathogens remains largely unknown. Because recognition and clearance of inhaled particulates and microbes are largely mediated by pattern recognition receptors (PRRs) on the surface of AM, we hypothesized that exposure to SiO2 limits the ability of AM to respond to bacterial challenge by altering PRR expression. Alveolar and bone marrow-derived macrophages downregulate TLR2 expression following acute SiO2 exposure (e.g., 4 h). Interestingly, these responses were dependent on interactions between SiO2 and the class A scavenger receptor CD204, but not MARCO. Furthermore, SiO2 exposure decreased uptake of fluorescently labeled Pam2CSK4 and Pam3CSK4, resulting in reduced secretion of IL-1β, but not IL-6. Collectively, our data suggest that SiO2 exposure alters AM phenotype, which in turn affects their ability to uptake and respond to bacterial lipoproteins. PMID:26913035

  18. Differential involvement of the shell and core subterritories of the nucleus accumbens in latent inhibition and amphetamine-induced activity.

    PubMed

    Weiner, I; Gal, G; Rawlins, J N; Feldon, J

    1996-11-01

    Latent inhibition (LI) consists of retardation in conditioning to a stimulus as a consequence of its prior non-reinforced pre-exposure. In view of findings that LI is disrupted in acute schizophrenic patients and evidence from animal experiments pointing to the involvement of the mesolimbic dopamine (DA) system in this phenomenon, the present study investigated the effects of electrolytic lesions to the shell and core subterritories of the nucleus accumbens on LI in rats (Expt. 1). LI was indexed by the amount of suppression of drinking in the presence of a tone that was either pre-exposed or not prior to its pairing with reinforcement (a foot shock). Expt.2 tested the effects of the DA antagonist, haloperidol, on LI in shell- and core-lesioned animals. Expt. 3 tested the effects of shell and core lesions on spontaneous and amphetamine-induced locomotion. In Expt. 1, LI, i.e., lower suppression of drinking in the pre-exposed as compared to the non-pre-exposed animals, was obtained in the sham-operated condition. Core and shell lesions produced distinct effects on LI. Animals with core lesions developed LI, but exhibited an overall lower suppression of drinking in comparison to the sham-operated animals. In contrast, shell lesions led to a disappearance of LI. Expt. 2 replicated the differential effects of shell and core lesions on LI, although in this experiment, core lesion did not attenuate suppression of drinking. Haloperidol prevented shell-induced abolition of LI. In Expt. 3, shell- but not core-lesioned animals were more active than sham controls following amphetamine administration. These results provide evidence for functional differences between the shell and core subregions, as well as for the involvement of the mesolimbic DA system in LI. PMID:8950008

  19. Anopheles gambiae Ag-STAT, a new insect member of the STAT family, is activated in response to bacterial infection.

    PubMed

    Barillas-Mury, C; Han, Y S; Seeley, D; Kafatos, F C

    1999-02-15

    A new insect member of the STAT family of transcription factors (Ag-STAT) has been cloned from the human malaria vector Anopheles gambiae. The domain involved in DNA interaction and the SH2 domain are well conserved. Ag-STAT is most similar to Drosophila D-STAT and to vertebrate STATs 5 and 6, constituting a proposed ancient class A of the STAT family. The mRNA is expressed at all developmental stages, and the protein is present in hemocytes, pericardial cells, midgut, skeletal muscle and fat body cells. There is no evidence of transcriptional activation following bacterial challenge. However, bacterial challenge results in nuclear translocation of Ag-STAT protein in fat body cells and induction of DNA-binding activity that recognizes a STAT target site. In vitro treatment with pervanadate (vanadate and H2O2) translocates Ag-STAT to the nucleus in midgut epithelial cells. This is the first evidence of direct participation of the STAT pathway in immune responses in insects. PMID:10022838

  20. The majority of in vitro macrophage activation exhibited by extracts of some immune enhancing botan