Sample records for obligate intracellular pathogen

  1. Genetic Systems for Studying Obligate Intracellular Pathogens: An Update

    PubMed Central

    Wood, David O.; Wood, Raphael R.; Tucker, Aimee M.

    2013-01-01

    Rapid advancements in the genetic manipulation of obligate intracellular bacterial pathogens have been made over the past two years. In this paper we attempt to summarize the work published since 2011 that documents these exciting accomplishments. While each genus comprising this diverse group of pathogens poses unique problems, requiring modifications of established techniques and the introduction of new tools, all appear amenable to genetic analysis. Significantly, the field is moving forward from a focus on the identification and development of genetic techniques to their application in addressing critical questions related to mechanisms of bacterial pathogenicity and the requirements of obligate intracellular growth. PMID:24581687

  2. Advances in genetic manipulation of obligate intracellular bacterial pathogens.

    PubMed

    Beare, Paul A; Sandoz, Kelsi M; Omsland, Anders; Rockey, Daniel D; Heinzen, Robert A

    2011-01-01

    Infections by obligate intracellular bacterial pathogens result in significant morbidity and mortality worldwide. These bacteria include Chlamydia spp., which causes millions of cases of sexually transmitted disease and blinding trachoma annually, and members of the ?-proteobacterial genera Anaplasma, Ehrlichia, Orientia, and Rickettsia, agents of serious human illnesses including epidemic typhus. Coxiella burnetii, the agent of human Q fever, has also been considered a prototypical obligate intracellular bacterium, but recent host cell-free (axenic) growth has rescued it from obligatism. The historic genetic intractability of obligate intracellular bacteria has severely limited molecular dissection of their unique lifestyles and virulence factors involved in pathogenesis. Host cell restricted growth is a significant barrier to genetic transformation that can make simple procedures for free-living bacteria, such as cloning, exceedingly difficult. Low transformation efficiency requiring long-term culture in host cells to expand small transformant populations is another obstacle. Despite numerous technical limitations, the last decade has witnessed significant gains in genetic manipulation of obligate intracellular bacteria including allelic exchange. Continued development of genetic tools should soon enable routine mutation and complementation strategies for virulence factor discovery and stimulate renewed interest in these refractory pathogens. In this review, we discuss the technical challenges associated with genetic transformation of obligate intracellular bacteria and highlight advances made with individual genera. PMID:21833334

  3. Pathogenic Potential of Novel Chlamydiae and Diagnostic Approaches to Infections Due to These Obligate Intracellular Bacteria

    PubMed Central

    Corsaro, Daniele; Greub, Gilbert

    2006-01-01

    Novel chlamydiae are newly recognized members of the phylum Chlamydiales that are only distantly related to the classic Chlamydiaceae, i.e., Chlamydia and Chlamydophila species. They also exibit an obligate biphasic intracellular life cycle within eukaryote host cells. Some of these new chlamydiae are currently considered potential emerging human and/or animal pathogens. Parachlamydia acanthamoebae and Simkania negevensis are both emerging respiratory human pathogens, Waddlia chondrophila could be a novel abortigenic bovine agent, and Piscichlamydia salmonis has recently been identified as an agent of the gill epitheliocystis in the Atlantic salmon. Fritschea spp. and Rhabdochlamydia spp. seem to be confined to arthropods, but some evidence for human exposure exists. In this review, we first summarize the data supporting a pathogenic potential of the novel chlamydiae for humans and other vertebrates and the interactions that most of these chlamydiae have with free-living amoebae. We then review the diagnostic approaches to infections potentially due to the novel chlamydiae, especially focusing on the currently available PCR-based protocols, mammalian cell culture, the amoebal coculture system, and serology. PMID:16614250

  4. Proteomic Profiling of the Outer Membrane Fraction of the Obligate Intracellular Bacterial Pathogen Ehrlichia ruminantium

    PubMed Central

    Moumène, Amal; Marcelino, Isabel; Ventosa, Miguel; Gros, Olivier; Lefrançois, Thierry; Vachiéry, Nathalie

    2015-01-01

    The outer membrane proteins (OMPs) of Gram-negative bacteria play a crucial role in virulence and pathogenesis. Identification of these proteins represents an important goal for bacterial proteomics, because it aids in vaccine development. Here, we have developed such an approach for Ehrlichia ruminantium, the obligate intracellular bacterium that causes heartwater. A preliminary whole proteome analysis of elementary bodies, the extracellular infectious form of the bacterium, had been performed previously, but information is limited about OMPs in this organism and about their role in the protective immune response. Identification of OMPs is also essential for understanding Ehrlichia’s OM architecture, and how the bacterium interacts with the host cell environment. First, we developed an OMP extraction method using the ionic detergent sarkosyl, which enriched the OM fraction. Second, proteins were separated via one-dimensional electrophoresis, and digested peptides were analyzed via nano-liquid chromatographic separation coupled with mass spectrometry (LC-MALDI-TOF/TOF). Of 46 unique proteins identified in the OM fraction, 18 (39%) were OMPs, including 8 proteins involved in cell structure and biogenesis, 4 in transport/virulence, 1 porin, and 5 proteins of unknown function. These experimental data were compared to the predicted subcellular localization of the entire E. ruminantium proteome, using three different algorithms. This work represents the most complete proteome characterization of the OM fraction in Ehrlichia spp. The study indicates that suitable subcellular fractionation experiments combined with straightforward computational analysis approaches are powerful for determining the predominant subcellular localization of the experimentally observed proteins. We identified proteins potentially involved in E. ruminantium pathogenesis, which are good novel targets for candidate vaccines. Thus, combining bioinformatics and proteomics, we discovered new OMPs for E. ruminantium that are valuable data for those investigating new vaccines against this organism. In summary, we provide both pioneering data and novel insights into the pathogenesis of this obligate intracellular bacterium. PMID:25710494

  5. Proteomic Profiling of the Outer Membrane Fraction of the Obligate Intracellular Bacterial Pathogen Ehrlichia ruminantium.

    PubMed

    Moumène, Amal; Marcelino, Isabel; Ventosa, Miguel; Gros, Olivier; Lefrançois, Thierry; Vachiéry, Nathalie; Meyer, Damien F; Coelho, Ana V

    2015-01-01

    The outer membrane proteins (OMPs) of Gram-negative bacteria play a crucial role in virulence and pathogenesis. Identification of these proteins represents an important goal for bacterial proteomics, because it aids in vaccine development. Here, we have developed such an approach for Ehrlichia ruminantium, the obligate intracellular bacterium that causes heartwater. A preliminary whole proteome analysis of elementary bodies, the extracellular infectious form of the bacterium, had been performed previously, but information is limited about OMPs in this organism and about their role in the protective immune response. Identification of OMPs is also essential for understanding Ehrlichia's OM architecture, and how the bacterium interacts with the host cell environment. First, we developed an OMP extraction method using the ionic detergent sarkosyl, which enriched the OM fraction. Second, proteins were separated via one-dimensional electrophoresis, and digested peptides were analyzed via nano-liquid chromatographic separation coupled with mass spectrometry (LC-MALDI-TOF/TOF). Of 46 unique proteins identified in the OM fraction, 18 (39%) were OMPs, including 8 proteins involved in cell structure and biogenesis, 4 in transport/virulence, 1 porin, and 5 proteins of unknown function. These experimental data were compared to the predicted subcellular localization of the entire E. ruminantium proteome, using three different algorithms. This work represents the most complete proteome characterization of the OM fraction in Ehrlichia spp. The study indicates that suitable subcellular fractionation experiments combined with straightforward computational analysis approaches are powerful for determining the predominant subcellular localization of the experimentally observed proteins. We identified proteins potentially involved in E. ruminantium pathogenesis, which are good novel targets for candidate vaccines. Thus, combining bioinformatics and proteomics, we discovered new OMPs for E. ruminantium that are valuable data for those investigating new vaccines against this organism. In summary, we provide both pioneering data and novel insights into the pathogenesis of this obligate intracellular bacterium. PMID:25710494

  6. Secretome of obligate intracellular Rickettsia.

    PubMed

    Gillespie, Joseph J; Kaur, Simran J; Rahman, M Sayeedur; Rennoll-Bankert, Kristen; Sears, Khandra T; Beier-Sexton, Magda; Azad, Abdu F

    2014-08-28

    The genus Rickettsia (Alphaproteobacteria, Rickettsiales, Rickettsiaceae) is comprised of obligate intracellular parasites, with virulent species of interest both as causes of emerging infectious diseases and for their potential deployment as bioterrorism agents. Currently, there are no effective commercially available vaccines, with treatment limited primarily to tetracycline antibiotics, although others (e.g. josamycin, ciprofloxacin, chloramphenicol, and azithromycin) are also effective. Much of the recent research geared toward understanding mechanisms underlying rickettsial pathogenicity has centered on characterization of secreted proteins that directly engage eukaryotic cells. Herein, we review all aspects of the Rickettsia secretome, including six secretion systems, 19 characterized secretory proteins, and potential moonlighting proteins identified on surfaces of multiple Rickettsia species. Employing bioinformatics and phylogenomics, we present novel structural and functional insight on each secretion system. Unexpectedly, our investigation revealed that the majority of characterized secretory proteins have not been assigned to their cognate secretion pathways. Furthermore, for most secretion pathways, the requisite signal sequences mediating translocation are poorly understood. As a blueprint for all known routes of protein translocation into host cells, this resource will assist research aimed at uniting characterized secreted proteins with their apposite secretion pathways. Furthermore, our work will help in the identification of novel secreted proteins involved in rickettsial 'life on the inside'. PMID:25168200

  7. Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microsporidia comprise a large phylum of obligate intracellular eukaryotes that are fungalrelated parasites responsible for widespread disease, and here we address questions about microsporidia biology and evolution. We sequenced three microsporidian genomes from two species, Nematocida parisii and...

  8. Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth.

    PubMed

    Cuomo, Christina A; Desjardins, Christopher A; Bakowski, Malina A; Goldberg, Jonathan; Ma, Amy T; Becnel, James J; Didier, Elizabeth S; Fan, Lin; Heiman, David I; Levin, Joshua Z; Young, Sarah; Zeng, Qiandong; Troemel, Emily R

    2012-12-01

    Microsporidia comprise a large phylum of obligate intracellular eukaryotes that are fungal-related parasites responsible for widespread disease, and here we address questions about microsporidia biology and evolution. We sequenced three microsporidian genomes from two species, Nematocida parisii and Nematocida sp1, which are natural pathogens of Caenorhabditis nematodes and provide model systems for studying microsporidian pathogenesis. We performed deep sequencing of transcripts from a time course of N. parisii infection. Examination of pathogen gene expression revealed compact transcripts and a dramatic takeover of host cells by Nematocida. We also performed phylogenomic analyses of Nematocida and other microsporidian genomes to refine microsporidian phylogeny and identify evolutionary events of gene loss, acquisition, and modification. In particular, we found that all microsporidia lost the tumor-suppressor gene retinoblastoma, which we speculate could accelerate the parasite cell cycle and increase the mutation rate. We also found that microsporidia acquired transporters that could import nucleosides to fuel rapid growth. In addition, microsporidian hexokinases gained secretion signal sequences, and in a functional assay these were sufficient to export proteins out of the cell; thus hexokinase may be targeted into the host cell to reprogram it toward biosynthesis. Similar molecular changes appear during formation of cancer cells and may be evolutionary strategies adopted independently by microsporidia to proliferate rapidly within host cells. Finally, analysis of genome polymorphisms revealed evidence for a sexual cycle that may provide genetic diversity to alleviate problems caused by clonal growth. Together these events may explain the emergence and success of these diverse intracellular parasites. PMID:22813931

  9. Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth

    PubMed Central

    Cuomo, Christina A.; Desjardins, Christopher A.; Bakowski, Malina A.; Goldberg, Jonathan; Ma, Amy T.; Becnel, James J.; Didier, Elizabeth S.; Fan, Lin; Heiman, David I.; Levin, Joshua Z.; Young, Sarah; Zeng, Qiandong; Troemel, Emily R.

    2012-01-01

    Microsporidia comprise a large phylum of obligate intracellular eukaryotes that are fungal-related parasites responsible for widespread disease, and here we address questions about microsporidia biology and evolution. We sequenced three microsporidian genomes from two species, Nematocida parisii and Nematocida sp1, which are natural pathogens of Caenorhabditis nematodes and provide model systems for studying microsporidian pathogenesis. We performed deep sequencing of transcripts from a time course of N. parisii infection. Examination of pathogen gene expression revealed compact transcripts and a dramatic takeover of host cells by Nematocida. We also performed phylogenomic analyses of Nematocida and other microsporidian genomes to refine microsporidian phylogeny and identify evolutionary events of gene loss, acquisition, and modification. In particular, we found that all microsporidia lost the tumor-suppressor gene retinoblastoma, which we speculate could accelerate the parasite cell cycle and increase the mutation rate. We also found that microsporidia acquired transporters that could import nucleosides to fuel rapid growth. In addition, microsporidian hexokinases gained secretion signal sequences, and in a functional assay these were sufficient to export proteins out of the cell; thus hexokinase may be targeted into the host cell to reprogram it toward biosynthesis. Similar molecular changes appear during formation of cancer cells and may be evolutionary strategies adopted independently by microsporidia to proliferate rapidly within host cells. Finally, analysis of genome polymorphisms revealed evidence for a sexual cycle that may provide genetic diversity to alleviate problems caused by clonal growth. Together these events may explain the emergence and success of these diverse intracellular parasites. PMID:22813931

  10. Rickettsia Phylogenomics: Unwinding the Intricacies of Obligate Intracellular Life

    PubMed Central

    Gillespie, Joseph J.; Williams, Kelly; Shukla, Maulik; Snyder, Eric E.; Nordberg, Eric K.; Ceraul, Shane M.; Dharmanolla, Chitti; Rainey, Daphne; Soneja, Jeetendra; Shallom, Joshua M.; Vishnubhat, Nataraj Dongre; Wattam, Rebecca; Purkayastha, Anjan; Czar, Michael; Crasta, Oswald; Setubal, Joao C.; Azad, Abdu F.; Sobral, Bruno S.

    2008-01-01

    Background Completed genome sequences are rapidly increasing for Rickettsia, obligate intracellular ?-proteobacteria responsible for various human diseases, including epidemic typhus and Rocky Mountain spotted fever. In light of phylogeny, the establishment of orthologous groups (OGs) of open reading frames (ORFs) will distinguish the core rickettsial genes and other group specific genes (class 1 OGs or C1OGs) from those distributed indiscriminately throughout the rickettsial tree (class 2 OG or C2OGs). Methodology/Principal Findings We present 1823 representative (no gene duplications) and 259 non-representative (at least one gene duplication) rickettsial OGs. While the highly reductive (?1.2 MB) Rickettsia genomes range in predicted ORFs from 872 to 1512, a core of 752 OGs was identified, depicting the essential Rickettsia genes. Unsurprisingly, this core lacks many metabolic genes, reflecting the dependence on host resources for growth and survival. Additionally, we bolster our recent reclassification of Rickettsia by identifying OGs that define the AG (ancestral group), TG (typhus group), TRG (transitional group), and SFG (spotted fever group) rickettsiae. OGs for insect-associated species, tick-associated species and species that harbor plasmids were also predicted. Through superimposition of all OGs over robust phylogeny estimation, we discern between C1OGs and C2OGs, the latter depicting genes either decaying from the conserved C1OGs or acquired laterally. Finally, scrutiny of non-representative OGs revealed high levels of split genes versus gene duplications, with both phenomena confounding gene orthology assignment. Interestingly, non-representative OGs, as well as OGs comprised of several gene families typically involved in microbial pathogenicity and/or the acquisition of virulence factors, fall predominantly within C2OG distributions. Conclusion/Significance Collectively, we determined the relative conservation and distribution of 14354 predicted ORFs from 10 rickettsial genomes across robust phylogeny estimation. The data, available at PATRIC (PathoSystems Resource Integration Center), provide novel information for unwinding the intricacies associated with Rickettsia pathogenesis, expanding the range of potential diagnostic, vaccine and therapeutic targets. PMID:19194535

  11. Metabolic Interdependence of Obligate Intracellular Bacteria and Their Insect Hosts†

    PubMed Central

    Zientz, Evelyn; Dandekar, Thomas; Gross, Roy

    2004-01-01

    Mutualistic associations of obligate intracellular bacteria and insects have attracted much interest in the past few years due to the evolutionary consequences for their genome structure. However, much less attention has been paid to the metabolic ramifications for these endosymbiotic microorganisms, which have to compete with but also to adapt to another metabolism—that of the host cell. This review attempts to provide insights into the complex physiological interactions and the evolution of metabolic pathways of several mutualistic bacteria of aphids, ants, and tsetse flies and their insect hosts. PMID:15590782

  12. Molecular pathogenesis of the obligate intracellular bacterium Coxiella burnetii

    PubMed Central

    van Schaik, Erin J.; Chen, Chen; Mertens, Katja; Weber, Mary M.; Samuel, James E.

    2014-01-01

    The agent of Q fever, Coxiella burnetii, is an obligate intracellular bacterium that causes acute and chronic infections. The study of C. burnetii pathogenesis has benefited from two recent fundamental advances: improved genetic tools and the ability to grow the bacterium in extracellular media. In this Review, we describe how these recent advances have improved our understanding of C. burnetii invasion and host cell modulation, including the formation of replication-permissive Coxiella-containing vacuoles. Furthermore, we describe the Dot/Icm (defect in organelle trafficking/intracellular multiplication) system, which is used by C. burnetii to secrete a range of effector proteins into the host cell, and we discuss the role of these effectors in remodelling the host cell. PMID:23797173

  13. Genetic regulation of resistance to intracellular pathogens

    Microsoft Academic Search

    Emil Skamene; Philippe Gros; Adrien Forget; Patricia A. L. Kongshavn; Carole St Charles; Benjamin A. Taylor

    1982-01-01

    Natural resistance of mice to infections with Salmonella typhimurium and Leishmania donovani is regulated by chromosome 1 gene(s) designated Ity and Lsh, respectively1,2. Given the fact that these two microorganisms are taxonomically and antigenically distinct, and yet the host response to them is regulated by the same locus or complex3,4, one might expect that the resistance to other intracellular pathogens

  14. A systems biological view of intracellular pathogens.

    PubMed

    Beiting, Daniel P; Roos, David S

    2011-03-01

    As biomedical research becomes increasingly data-intensive, it is increasingly essential to integrate genomic-scale datasets, so as to generate a more holistic picture of complex biological processes. The systems biology paradigm may differ in strategy from traditional reductionist scientific methods, but the goal remains the same: to generate tenable hypotheses driving the experimental elucidation of biological mechanisms. Intracellular pathogens provide an excellent opportunity for systems analysis, as many of these organisms are amenable to genetic manipulation, allowing their biology to be played off against that of the host. Moreover, many of the most fundamental biological properties of these microbes (host cell invasion, immune evasion, intracellular replication, long-term persistence) are directly linked to pathogenesis and readily quantifiable using genomic-scale technologies. In this review, we summarize and discuss some of the available and foreseeable functional genomics datasets pertaining to host-pathogen interactions and suggest that the host-pathogen interface represents a promising, tractable challenge for systems biological analysis. Success will require developing and leveraging new technologies, expanding data acquisition, and increasing public access to comprehensive datasets, to assemble quantitative and testable models of the host-pathogen relationship. PMID:21349090

  15. Survival Strategy of Obligately Intracellular Ehrlichia chaffeensis: Novel Modulation of Immune Response and Host Cell Cycles

    PubMed Central

    Zhang, Jian-zhi; Sinha, Mala; Luxon, Bruce A.; Yu, Xue-jie

    2004-01-01

    Ehrlichia chaffeensis is an obligatory intracellular bacterium which resides in an early endosome in monocytes. E. chaffeensis infection in a human monocyte cell line (THP1) significantly altered the transcriptional levels of 4.5% of host genes, including those coding for apoptosis inhibitors, proteins regulating cell differentiation, signal transduction, proinflammatory cytokines, biosynthetic and metabolic proteins, and membrane trafficking proteins. The transcriptional profile of the host cell revealed key themes in the pathogenesis of Ehrlichia. First, E. chaffeensis avoided stimulation of or repressed the transcription of cytokines involved in the early innate immune response and cell-mediated immune response to intracellular microbes, such as the interleukin-12 (IL-12), IL-15, and IL-18 genes, which might make Ehrlichia a stealth organism for the macrophage. Second, E. chaffeensis up-regulated NF-?B and apoptosis inhibitors and differentially regulated cell cyclins and CDK expression, which may enhance host cell survival. Third, E. chaffeensis also inhibited the gene transcription of RAB5A, SNAP23, and STX16, which are involved in membrane trafficking. By comparing the transcriptional response of macrophages infected with other bacteria and that of macrophages infected with E. chaffeensis, we have identified few genes that are commonly induced and no commonly repressed genes. These results illustrate the stereotyped macrophage response to other pathogens, in contrast with the novel host response to obligate intracellular Ehrlichia, whose survival depends entirely on a long evolutionary process of outmaneuvering macrophages. PMID:14688131

  16. Pyroptotic cell death defends against intracellular pathogens.

    PubMed

    Jorgensen, Ine; Miao, Edward A

    2015-05-01

    Inflammatory caspases play a central role in innate immunity by responding to cytosolic signals and initiating a twofold response. First, caspase-1 induces the activation and secretion of the two prominent pro-inflammatory cytokines, interleukin-1? (IL-1?) and IL-18. Second, either caspase-1 or caspase-11 can trigger a form of lytic, programmed cell death called pyroptosis. Pyroptosis operates to remove the replication niche of intracellular pathogens, making them susceptible to phagocytosis and killing by a secondary phagocyte. However, aberrant, systemic activation of pyroptosis in vivo may contribute to sepsis. Emphasizing the efficiency of inflammasome detection of microbial infections, many pathogens have evolved to avoid or subvert pyroptosis. This review focuses on molecular and morphological characteristics of pyroptosis and the individual inflammasomes and their contribution to defense against infection in mice and humans. PMID:25879289

  17. Ileal Symbiont Intracellularis, an Obligate Intracellular Bacterium of Porcine Intestines Showing a Relationship to Desulfovibrio Species

    Microsoft Academic Search

    CONNIE J. GEBHART; SUSAN M. BARNS; GAO-FENG LIN

    A new genus and species of obligate intracellular bacteria found in porcine intestines are described. Growth on any bacteriological medium deprived of living cells has not been demonstrated. The organism has been grown intracellularly in cell culture. The 16s rRNA gene sequence data, DNA probe results, and microscopic observations provide evidence that these bacteria differ from those in other described

  18. The genome of obligately intracellular Ehrlichia canis revealsthemes of complex membrane structure and immune evasion strategies

    SciTech Connect

    Mavromatis, K.; Kuyler Doyle, C.; Lykidis, A.; Ivanova, N.; Francino, P.; Chain, P.; Shin, M.; Malfatti, S.; Larimer, F.; Copeland,A.; Detter, J.C.; Land, M.; Richardson, P.M.; Yu, X.J.; Walker, D.H.; McBride, J.W.; Kyrpides, N.C.

    2005-09-01

    Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, a-proteobacterium is the primary etiologic agent of globally distributed canine monocytic ehrlichiosis. Complete genome sequencing revealed that the E. canis genome consists of a single circular chromosome of 1,315,030 bp predicted to encode 925 proteins, 40 stable RNA species, and 17 putative pseudogenes, and a substantial proportion of non-coding sequence (27 percent). Interesting genome features include a large set of proteins with transmembrane helices and/or signal sequences, and a unique serine-threonine bias associated with the potential for O-glycosylation that was prominent in proteins associated with pathogen-host interactions. Furthermore, two paralogous protein families associated with immune evasion were identified, one of which contains poly G:C tracts, suggesting that they may play a role in phase variation and facilitation of persistent infections. Proteins associated with pathogen-host interactions were identified including a small group of proteins (12) with tandem repeats and another with eukaryotic-like ankyrin domains (7).

  19. Alternative Splicing in the Obligate Biotrophic Oomycete Pathogen Pseudoperonospora cubensis.

    PubMed

    Burkhardt, Alyssa; Buchanan, Alex; Cumbie, Jason S; Savory, Elizabeth A; Chang, Jeff H; Day, Brad

    2015-03-01

    Pseudoperonospora cubensis is an obligate pathogen and causative agent of cucurbit downy mildew. To help advance our understanding of the pathogenicity of P. cubensis, we used RNA-Seq to improve the quality of its reference genome sequence. We also characterized the RNA-Seq dataset to inventory transcript isoforms and infer alternative splicing during different stages of its development. Almost half of the original gene annotations were improved and nearly 4,000 previously unannotated genes were identified. We also demonstrated that approximately 24% of the expressed genome and nearly 55% of the intron-containing genes from P. cubensis had evidence for alternative splicing. Our analyses revealed that intron retention is the predominant alternative splicing type in P. cubensis, with alternative 5'- and alternative 3'-splice sites occurring at lower frequencies. Representatives of the newly identified genes and predicted alternatively spliced transcripts were experimentally validated. The results presented herein highlight the utility of RNA-Seq for improving draft genome annotations and, through this approach, we demonstrate that alternative splicing occurs more frequently than previously predicted. In total, the current study provides evidence that alternative splicing plays a key role in transcriptome regulation and proteome diversification in plant-pathogenic oomycetes. PMID:25372122

  20. Evolutionary Genomics of a Temperate Bacteriophage in an Obligate Intracellular Bacteria (Wolbachia)

    E-print Network

    Bordenstein, Seth

    Evolutionary Genomics of a Temperate Bacteriophage in an Obligate Intracellular Bacteria (Wolbachia, Vanderbilt University, Nashville, Tennessee, United States of America Abstract Genome evolution of bacteria is usually influenced by ecology, such that bacteria with a free-living stage have large genomes and high

  1. Caenorhabditis elegans as a model for intracellular pathogen infection

    PubMed Central

    Balla, Keir M.; Troemel, Emily R.

    2014-01-01

    Summary The genetically tractable nematode Caenorhabditis elegans is a convenient host for studies of pathogen infection. With the recent identification of two types of natural intracellular pathogens of C. elegans, this host now provides the opportunity to examine interactions and defence against intracellular pathogens in a whole-animal model for infection. C. elegans is the natural host for a genus of microsporidia, which comprise a phylum of fungal-related pathogens of widespread importance for agriculture and medicine. More recently, C. elegans has been shown to be a natural host for viruses related to the Nodaviridae family. Both microsporidian and viral pathogens infect the C. elegans intestine, which is composed of cells that share striking similarities to human intestinal epithelial cells. Because C. elegans nematodes are transparent, these infections provide a unique opportunity to visualize differentiated intestinal cells in vivo during the course of intracellular infection. Together, these two natural pathogens of C. elegans provide powerful systems in which to study microbial pathogenesis and host responses to intracellular infection. PMID:23617769

  2. Caenorhabditis elegans as a model for intracellular pathogen infection.

    PubMed

    Balla, Keir M; Troemel, Emily R

    2013-08-01

    The genetically tractable nematode Caenorhabditis elegans is a convenient host for studies of pathogen infection. With the recent identification of two types of natural intracellular pathogens of C. elegans, this host now provides the opportunity to examine interactions and defence against intracellular pathogens in a whole-animal model for infection. C. elegans is the natural host for a genus of microsporidia, which comprise a phylum of fungal-related pathogens of widespread importance for agriculture and medicine. More recently, C. elegans has been shown to be a natural host for viruses related to the Nodaviridae family. Both microsporidian and viral pathogens infect the C. elegans intestine, which is composed of cells that share striking similarities to human intestinal epithelial cells. Because C. elegans nematodes are transparent, these infections provide a unique opportunity to visualize differentiated intestinal cells in vivo during the course of intracellular infection. Together, these two natural pathogens of C. elegans provide powerful systems in which to study microbial pathogenesis and host responses to intracellular infection. PMID:23617769

  3. Intracellular activity of azithromycin against bacterial enteric pathogens.

    PubMed Central

    Rakita, R M; Jacques-Palaz, K; Murray, B E

    1994-01-01

    Azithromycin, a new azalide antibiotic, is active in vitro against a variety of enteric bacterial pathogens. Since it is concentrated inside human neutrophils and other cells, it might be particularly useful in the treatment of infections caused by enteropathogens that invade host tissues. The intracellular activity of azithromycin against several enteric pathogens that had been phagocytosed by neutrophils was determined. Azithromycin was effective in reducing the intracellular viabilities of almost all strains tested, including representative strains of Salmonella, Shigella, and enteroinvasive, enteropathogenic, enterotoxigenic, and enterohemorrhagic Escherichia coli. Erythromycin was also effective in this model system, although azithromycin was generally more effective than erythromycin against strains of invasive enteric pathogens. Cefotaxime reduced intracellular bacterial viability to a lesser extent than either azithromycin or erythromycin. The presence of neutrophils did not significantly affect the activity of azithromycin in this system. Azithromycin may be a useful agent for the treatment of bacterial diarrhea, and clinical trials should be considered. PMID:7810998

  4. Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms

    PubMed Central

    Mansilla Pareja, Maria Eugenia; Colombo, Maria I.

    2013-01-01

    Autophagy is involved in several physiological and pathological processes. One of the key roles of the autophagic pathway is to participate in the first line of defense against the invasion of pathogens, as part of the innate immune response. Targeting of intracellular bacteria by the autophagic machinery, either in the cytoplasm or within vacuolar compartments, helps to control bacterial proliferation in the host cell, controlling also the spreading of the infection. In this review we will describe the means used by diverse bacterial pathogens to survive intracellularly and how they are recognized by the autophagic molecular machinery, as well as the mechanisms used to avoid autophagic clearance. PMID:24137567

  5. Bacterial Pathogens Commandeer Rab GTPases to Establish Intracellular Niches

    PubMed Central

    Stein, Mary-Pat; Müller, Matthias P.; Wandinger-Ness, Angela

    2012-01-01

    Intracellular bacterial pathogens deploy virulence factors termed effectors to inhibit degradation by host cells and to establish intracellular niches where growth and differentiation take place. Here, we describe mechanisms by which human bacterial pathogens (including Chlamydiae; Coxiella burnetii; Helicobacter pylori; Legionella pneumophila; Listeria monocytogenes; Mycobacteria; Pseudomonas aeruginosa, Salmonella enterica) modulate endocytic and exocytic Rab GTPases in order to thrive in host cells. Host cell Rab GTPases are critical for intracellular transport following pathogen phagocytosis or endocytosis. At the molecular level bacterial effectors hijack Rab protein function to: evade degradation, direct transport to particular intracellular locations, and monopolize host vesicles carrying molecules that are needed for a stable niche and/or bacterial growth and differentiation. Bacterial effectors may serve as specific receptors for Rab GTPases or as enzymes that post-translationally modify Rab proteins or endosomal membrane lipids required for Rab function. Emerging data indicate that bacterial effector expression is temporally and spatially regulated and multiple virulence factors may act concertedly to usurp Rab GTPase function, alter signaling and ensure niche establishment and intracellular bacterial growth, making this field an exciting area for further study. PMID:22901006

  6. Disrupting Protein Expression with Peptide Nucleic Acids Reduces Infection by Obligate Intracellular Rickettsia

    PubMed Central

    Pelc, Rebecca S.; McClure, Jennifer C.; Kaur, Simran J.; Sears, Khandra T.; Rahman, M. Sayeedur; Ceraul, Shane M.

    2015-01-01

    Peptide Nucleic Acids (PNAs) are single-stranded synthetic nucleic acids with a pseudopeptide backbone in lieu of the phosphodiester linked sugar and phosphate found in traditional oligos. PNA designed complementary to the bacterial Shine-Dalgarno or start codon regions of mRNA disrupts translation resulting in the transient reduction in protein expression. This study examines the use of PNA technology to interrupt protein expression in obligate intracellular Rickettsia sp. Their historically intractable genetic system limits characterization of protein function. We designed PNA targeting mRNA for rOmpB from Rickettsia typhi and rickA from Rickettsia montanensis, ubiquitous factors important for infection. Using an in vitro translation system and competitive binding assays, we determined that our PNAs bind target regions. Electroporation of R. typhi and R. montanensis with PNA specific to rOmpB and rickA, respectively, reduced the bacteria’s ability to infect host cells. These studies open the possibility of using PNA to suppress protein synthesis in obligate intracellular bacteria. PMID:25781160

  7. Lateral Phage Transfer in Obligate Intracellular Bacteria (Wolbachia): Verification from Natural Populations

    PubMed Central

    Chafee, Meghan E.; Funk, Daniel J.; Harrison, Richard G.; Bordenstein, Seth R.

    2010-01-01

    Lateral transfer of mobile DNA is a hallmark of bacteria with a free-living replicative stage; however, its significance in obligate intracellular bacteria and other heritable endosymbionts remains controversial. Comparative sequence analyses from laboratory stocks infected with Wolbachia pipientis provide some of the most compelling evidence that bacteriophage WO-B transfers laterally between infections of the same insect host. Lateral transfer between coinfections, however, has been evaluated neither in natural populations nor between closely related Wolbachia strains. Here, we analyze bacterial and phage genes from two pairs of natural sympatric field isolates, of Gryllus pennsylvanicus field crickets and of Neochlamisus bebbianae leaf beetles, to demonstrate WO-B transfers between supergroup B Wolbachia. N. bebbianae revealed the highest number of phage haplotypes yet recorded, hinting that lab lines could underestimate phage haplotype variation and lateral transfer. Finally, using the approximate age of insect host species as the maximum available time for phage transfer between host-associated bacteria, we very conservatively estimate phage WO-B transfer to occur at least once every 0–5.4 My within a host species. Increasing discoveries of mobile elements, intragenic recombination, and bacterial coinfections in host-switching obligate intracellular bacteria specify that mobile element transfer is common in these species. PMID:19906794

  8. Glutathione activates virulence gene expression of an intracellular pathogen.

    PubMed

    Reniere, Michelle L; Whiteley, Aaron T; Hamilton, Keri L; John, Sonya M; Lauer, Peter; Brennan, Richard G; Portnoy, Daniel A

    2015-01-01

    Intracellular pathogens are responsible for much of the world-wide morbidity and mortality due to infectious diseases. To colonize their hosts successfully, pathogens must sense their environment and regulate virulence gene expression appropriately. Accordingly, on entry into mammalian cells, the facultative intracellular bacterial pathogen Listeria monocytogenes remodels its transcriptional program by activating the master virulence regulator PrfA. Here we show that bacterial and host-derived glutathione are required to activate PrfA. In this study a genetic selection led to the identification of a bacterial mutant in glutathione synthase that exhibited reduced virulence gene expression and was attenuated 150-fold in mice. Genome sequencing of suppressor mutants that arose spontaneously in vivo revealed a single nucleotide change in prfA that locks the protein in the active conformation (PrfA*) and completely bypassed the requirement for glutathione during infection. Biochemical and genetic studies support a model in which glutathione-dependent PrfA activation is mediated by allosteric binding of glutathione to PrfA. Whereas glutathione and other low-molecular-weight thiols have important roles in redox homeostasis in all forms of life, here we demonstrate that glutathione represents a critical signalling molecule that activates the virulence of an intracellular pathogen. PMID:25567281

  9. Metabolic host responses to infection by intracellular bacterial pathogens

    PubMed Central

    Eisenreich, Wolfgang; Heesemann, Jürgen; Rudel, Thomas; Goebel, Werner

    2013-01-01

    The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies. PMID:23847769

  10. Intracellular immunity: finding the enemy within—how cells recognize and respond to intracellular pathogens

    PubMed Central

    Tam, Jerry C. H.; Jacques, David A.

    2014-01-01

    Historically, once a cell became infected, it was considered to be beyond all help. By this stage, the invading pathogen had breached the innate defenses and was beyond the reach of the humoral arm of the adaptive immune response. The pathogen could still be removed by cell-mediated immunity (e.g., by NK cells or cytotoxic T lymphocytes), but these mechanisms necessitated the destruction of the infected cell. However, in recent years, it has become increasingly clear that many cells possess sensor and effector mechanisms for dealing with intracellular pathogens. Most of these mechanisms are not restricted to professional immune cells nor do they all necessitate the destruction of the host. In this review, we examine the strategies that cells use to detect and destroy pathogens once the cell membrane has been penetrated. PMID:24899588

  11. Biological Properties and Cell Tropism of Chp2, a Bacteriophage of the Obligate Intracellular Bacterium Chlamydophila abortus

    Microsoft Academic Search

    J. S. Everson; S. A. Garner; B. Fane; B.-L. Liu; P. R. Lambden; I. N. Clarke

    2002-01-01

    A number of bacteriophages belonging to the Microviridae have been described infecting chlamydiae. Phy- logenetic studies divide the Chlamydiaceae into two distinct genera, Chlamydia and Chlamydophila, containing three and six different species, respectively. In this work we investigated the biological properties and host range of the recently described bacteriophage Chp2 that was originally discovered in Chlamydophila abortus. The obligate intracellular

  12. Nutrient salvaging and metabolism by the intracellular pathogen Legionella pneumophila

    PubMed Central

    Fonseca, Maris V.; Swanson, Michele S.

    2014-01-01

    The Gram-negative bacterium Legionella pneumophila is ubiquitous in freshwater environments as a free-swimming organism, resident of biofilms, or parasite of protozoa. If the bacterium is aerosolized and inhaled by a susceptible human host, it can infect alveolar macrophages and cause a severe pneumonia known as Legionnaires' disease. A sophisticated cell differentiation program equips L. pneumophila to persist in both extracellular and intracellular niches. During its life cycle, L. pneumophila alternates between at least two distinct forms: a transmissive form equipped to infect host cells and evade lysosomal degradation, and a replicative form that multiplies within a phagosomal compartment that it has retooled to its advantage. The efficient changeover between transmissive and replicative states is fundamental to L. pneumophila's fitness as an intracellular pathogen. The transmission and replication programs of L. pneumophila are governed by a number of metabolic cues that signal whether conditions are favorable for replication or instead trigger escape from a spent host. Several lines of experimental evidence gathered over the past decade establish strong links between metabolism, cellular differentiation, and virulence of L. pneumophila. Herein, we focus on current knowledge of the metabolic components employed by intracellular L. pneumophila for cell differentiation, nutrient salvaging and utilization of host factors. Specifically, we highlight the metabolic cues that are coupled to bacterial differentiation, nutrient acquisition systems, and the strategies utilized by L. pneumophila to exploit host metabolites for intracellular replication. PMID:24575391

  13. The Obligate Intracellular Parasite Toxoplasma gondii Secretes a Soluble Phosphatidylserine Decarboxylase*

    PubMed Central

    Gupta, Nishith; Hartmann, Anne; Lucius, Richard; Voelker, Dennis R.

    2012-01-01

    Toxoplasma gondii is an obligate intracellular parasite capable of causing fatal infections in immunocompromised individuals and neonates. Examination of the phosphatidylserine (PtdSer) metabolism of T. gondii reveals that the parasite secretes a soluble form of PtdSer decarboxylase (TgPSD1), which preferentially decarboxylates liposomal PtdSer with an apparent Km of 67 ?m. The specific enzyme activity increases by 3-fold during the replication of T. gondii, and soluble phosphatidylserine decarboxylase (PSD) accounts for ?20% of the total PSD, prior to the parasite egress from the host cells. Extracellular T. gondii secreted ?20% of its total PSD activity at 37 °C, and the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N?,N?-tetraacetic acid tetrakis (acetoxymethyl ester) inhibited the process by 50%. Cycloheximide, brefeldin A, ionic composition of the medium, and exogenous PtdSer did not modulate the enzyme secretion, which suggests a constitutive discharge of a presynthesized pool of PSD in axenic T. gondii. TgPSD1 consists of 968 amino acids with a 26-amino acid hydrophobic peptide at the N terminus and no predicted membrane domains. Parasites overexpressing TgPSD1-HA secreted 10-fold more activity compared with the parental strain. Exposure of apoptotic Jurkat cells to transgenic parasites demonstrated interfacial catalysis by secreted TgPSD1 that reduced host cell surface exposure of PtdSer. Immunolocalization experiments revealed that TgPSD1 resides in the dense granules of T. gondii and is also found in the parasitophorous vacuole of replicating parasites. Together, these findings demonstrate novel features of the parasite enzyme because a secreted, soluble, and interfacially active form of PSD has not been previously described for any organism. PMID:22563079

  14. Genome-wide screen for temperature-regulated genes of the obligate intracellular bacterium, Rickettsia typhi

    PubMed Central

    Dreher-Lesnick, Sheila M; Ceraul, Shane M; Rahman, M Sayeedur; Azad, Abdu F

    2008-01-01

    Background The ability of rickettsiae to survive in multiple eukaryotic host environments provides a good model for studying pathogen-host molecular interactions. Rickettsia typhi, the etiologic agent of murine typhus, is a strictly intracellular gram negative ?-proteobacterium, which is transmitted to humans by its arthropod vector, the oriental rat flea, Xenopsylla cheopis. Thus, R. typhi must cycle between mammalian and flea hosts, two drastically different environments. We hypothesize that temperature plays a role in regulating host-specific gene expression, allowing R. typhi to survive in mammalian and arthropod hosts. In this study, we used Affymetrix microarrays to screen for temperature-induced genes upon a temperature shift from 37°C to 25°C, mimicking the two different host temperatures in vitro. Results Temperature-responsive genes belonged to multiple functional categories including among others, transcription, translation, posttranslational modification/protein turnover/chaperones and intracellular trafficking and secretion. A large number of differentially expressed genes are still poorly characterized, and either have no known function or are not in the COG database. The microarray results were validated with quantitative real time RT-PCR. Conclusion This microarray screen identified various genes that were differentially expressed upon a shift in temperature from 37°C to 25°C. Further characterization of the identified genes may provide new insights into the ability of R. typhi to successfully transition between its mammalian and arthropod hosts. PMID:18412961

  15. The Genome Sequence of Rickettsia felis Identifies the First Putative Conjugative Plasmid in an Obligate Intracellular Parasite

    PubMed Central

    2005-01-01

    We sequenced the genome of Rickettsia felis, a flea-associated obligate intracellular ?-proteobacterium causing spotted fever in humans. Besides a circular chromosome of 1,485,148 bp, R. felis exhibits the first putative conjugative plasmid identified among obligate intracellular bacteria. This plasmid is found in a short (39,263 bp) and a long (62,829 bp) form. R. felis contrasts with previously sequenced Rickettsia in terms of many other features, including a number of transposases, several chromosomal toxin–antitoxin genes, many more spoT genes, and a very large number of ankyrin- and tetratricopeptide-motif-containing genes. Host-invasion-related genes for patatin and RickA were found. Several phenotypes predicted from genome analysis were experimentally tested: conjugative pili and mating were observed, as well as ?-lactamase activity, actin-polymerization-driven mobility, and hemolytic properties. Our study demonstrates that complete genome sequencing is the fastest approach to reveal phenotypic characters of recently cultured obligate intracellular bacteria. PMID:15984913

  16. Dual Mechanisms of Metabolite Acquisition by the Obligate Intracytosolic Pathogen Rickettsia prowazekii Reveal Novel Aspects of Triose Phosphate Transport

    PubMed Central

    Frohlich, Kyla M.

    2013-01-01

    Rickettsia prowazekii is an obligate intracytosolic pathogen and the causative agent of epidemic typhus fever in humans. As an evolutionary model of intracellular pathogenesis, rickettsiae are notorious for their use of transport systems that parasitize eukaryotic host cell biochemical pathways. Rickettsial transport systems for substrates found only in eukaryotic cell cytoplasm are uncommon among free-living microorganisms and often possess distinctive mechanisms. We previously reported that R. prowazekii acquires triose phosphates for phospholipid biosynthesis via the coordinated activities of a novel dihydroxyacetone phosphate transport system and an sn-glycerol-3-phosphate dehydrogenase (K. M. Frohlich et al., J. Bacteriol. 192:4281–4288, 2010). In the present study, we have determined that R. prowazekii utilizes a second, independent triose phosphate acquisition pathway whereby sn-glycerol-3-phosphate is directly transported and incorporated into phospholipids. Herein we describe the sn-glycerol-3-phosphate and dihydroxyacetone phosphate transport systems in isolated R. prowazekii with respect to kinetics, energy coupling, transport mechanisms, and substrate specificity. These data suggest the existence of multiple rickettsial triose phosphate transport systems. Furthermore, the R. prowazekii dihydroxyacetone phosphate transport systems displayed unexpected mechanistic properties compared to well-characterized triose phosphate transport systems from plant plastids. Questions regarding possible roles for dual-substrate acquisition pathways as metabolic virulence factors in the context of a pathogen undergoing reductive evolution are discussed. PMID:23772074

  17. Thymic Independence of Adaptive Immunity to the Intracellular Pathogen Shigella flexneri Serotype 2a

    Microsoft Academic Search

    ALAIN C. BORCZUK; MARCIA B. GOLDBERG

    1999-01-01

    Shigella flexneri is a facultative intracellular pathogen. While immunity to several intracellular pathogens is mediated by T lymphocytes, it is unknown whether cellular immune responses are important to adaptive immunity to S. flexneri. We show that vaccination with S. flexneri serotype 2a confers protection to mice that lack T lymphocytes or gamma interferon (IFN-g), specific depletion of T lymphocytes does

  18. Infection of zebrafish embryos with intracellular bacterial pathogens.

    PubMed

    Benard, Erica L; van der Sar, Astrid M; Ellett, Felix; Lieschke, Graham J; Spaink, Herman P; Meijer, Annemarie H

    2012-01-01

    Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen interactions. The major cell types of the innate immune system, macrophages and neutrophils, develop during the first days of embryogenesis prior to the maturation of lymphocytes that are required for adaptive immune responses. The ease of obtaining large numbers of embryos, their accessibility due to external development, the optical transparency of embryonic and larval stages, a wide range of genetic tools, extensive mutant resources and collections of transgenic reporter lines, all add to the versatility of the zebrafish model. Salmonella enterica serovar Typhimurium (S. typhimurium) and Mycobacterium marinum can reside intracellularly in macrophages and are frequently used to study host-pathogen interactions in zebrafish embryos. The infection processes of these two bacterial pathogens are interesting to compare because S. typhimurium infection is acute and lethal within one day, whereas M. marinum infection is chronic and can be imaged up to the larval stage. The site of micro-injection of bacteria into the embryo determines whether the infection will rapidly become systemic or will initially remain localized. A rapid systemic infection can be established by micro-injecting bacteria directly into the blood circulation via the caudal vein at the posterior blood island or via the Duct of Cuvier, a wide circulation channel on the yolk sac connecting the heart to the trunk vasculature. At 1 dpf, when embryos at this stage have phagocytically active macrophages but neutrophils have not yet matured, injecting into the blood island is preferred. For injections at 2-3 dpf, when embryos also have developed functional (myeloperoxidase-producing) neutrophils, the Duct of Cuvier is preferred as the injection site. To study directed migration of myeloid cells towards local infections, bacteria can be injected into the tail muscle, otic vesicle, or hindbrain ventricle. In addition, the notochord, a structure that appears to be normally inaccessible to myeloid cells, is highly susceptible to local infection. A useful alternative for high-throughput applications is the injection of bacteria into the yolk of embryos within the first hours after fertilization. Combining fluorescent bacteria and transgenic zebrafish lines with fluorescent macrophages or neutrophils creates ideal circumstances for multi-color imaging of host-pathogen interactions. This video article will describe detailed protocols for intravenous and local infection of zebrafish embryos with S. typhimurium or M. marinum bacteria and for subsequent fluorescence imaging of the interaction with cells of the innate immune system. PMID:22453760

  19. Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens

    PubMed Central

    Benard, Erica L.; van der Sar, Astrid M.; Ellett, Felix; Lieschke, Graham J.; Spaink, Herman P.; Meijer, Annemarie H.

    2012-01-01

    Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen interactions 1. The major cell types of the innate immune system, macrophages and neutrophils, develop during the first days of embryogenesis prior to the maturation of lymphocytes that are required for adaptive immune responses. The ease of obtaining large numbers of embryos, their accessibility due to external development, the optical transparency of embryonic and larval stages, a wide range of genetic tools, extensive mutant resources and collections of transgenic reporter lines, all add to the versatility of the zebrafish model. Salmonella enterica serovar Typhimurium (S. typhimurium) and Mycobacterium marinum can reside intracellularly in macrophages and are frequently used to study host-pathogen interactions in zebrafish embryos. The infection processes of these two bacterial pathogens are interesting to compare because S. typhimurium infection is acute and lethal within one day, whereas M. marinum infection is chronic and can be imaged up to the larval stage 2, 3. The site of micro-injection of bacteria into the embryo (Figure 1) determines whether the infection will rapidly become systemic or will initially remain localized. A rapid systemic infection can be established by micro-injecting bacteria directly into the blood circulation via the caudal vein at the posterior blood island or via the Duct of Cuvier, a wide circulation channel on the yolk sac connecting the heart to the trunk vasculature. At 1 dpf, when embryos at this stage have phagocytically active macrophages but neutrophils have not yet matured, injecting into the blood island is preferred. For injections at 2-3 dpf, when embryos also have developed functional (myeloperoxidase-producing) neutrophils, the Duct of Cuvier is preferred as the injection site. To study directed migration of myeloid cells towards local infections, bacteria can be injected into the tail muscle, otic vesicle, or hindbrain ventricle 4-6. In addition, the notochord, a structure that appears to be normally inaccessible to myeloid cells, is highly susceptible to local infection 7. A useful alternative for high-throughput applications is the injection of bacteria into the yolk of embryos within the first hours after fertilization 8. Combining fluorescent bacteria and transgenic zebrafish lines with fluorescent macrophages or neutrophils creates ideal circumstances for multi-color imaging of host-pathogen interactions. This video article will describe detailed protocols for intravenous and local infection of zebrafish embryos with S. typhimurium or M. marinum bacteria and for subsequent fluorescence imaging of the interaction with cells of the innate immune system. PMID:22453760

  20. Comparative Genomics Suggests That the Human Pathogenic Fungus Pneumocystis jirovecii Acquired Obligate Biotrophy through Gene Loss

    PubMed Central

    Cissé, Ousmane H.; Pagni, Marco; Hauser, Philippe M.

    2014-01-01

    Pneumocystis jirovecii is a fungal parasite that colonizes specifically humans and turns into an opportunistic pathogen in immunodeficient individuals. The fungus is able to reproduce extracellularly in host lungs without eliciting massive cellular death. The molecular mechanisms that govern this process are poorly understood, in part because of the lack of an in vitro culture system for Pneumocystis spp. In this study, we explored the origin and evolution of the putative biotrophy of P. jirovecii through comparative genomics and reconstruction of ancestral gene repertoires. We used the maximum parsimony method and genomes of related fungi of the Taphrinomycotina subphylum. Our results suggest that the last common ancestor of Pneumocystis spp. lost 2,324 genes in relation to the acquisition of obligate biotrophy. These losses may result from neutral drift and affect the biosyntheses of amino acids and thiamine, the assimilation of inorganic nitrogen and sulfur, and the catabolism of purines. In addition, P. jirovecii shows a reduced panel of lytic proteases and has lost the RNA interference machinery, which might contribute to its genome plasticity. Together with other characteristics, that is, a sex life cycle within the host, the absence of massive destruction of host cells, difficult culturing, and the lack of virulence factors, these gene losses constitute a unique combination of characteristics which are hallmarks of both obligate biotrophs and animal parasites. These findings suggest that Pneumocystis spp. should be considered as the first described obligate biotrophs of animals, whose evolution has been marked by gene losses. PMID:25062922

  1. Effects of cryopreservation at -80 degrees C on the formulation and pathogenicity of the obligate aphid pathogen Pandora nouryi.

    PubMed

    Zhou, Xiang; Feng, Ming-Guang; Huang, Zhi-Hong

    2014-01-01

    Cryopreservation at -80 degrees C is an alternative to liquid nitrogen storage for Entomophthorales. However, detailed studies about its effects on fungal pathogenicity and formulation are very limited. In the present study, the obligate aphid pathogen Pandora nouryi was formulated as mycelia grown on millet-gel granules after preservation as primary spores at -80 degrees C for 3-18 months, although its ability to produce infectious conidia gradually diminished. The sporulation capacity of this granular formulation was reduced to 18.5 x 10(4) conidia/mg after 18 months of storage, which was still higher than that of mycotized aphids. The half-decline time of sporulation capacity was computed as 13.6 months. The infectivity to the green peach aphid Myzus persicae had no significant decline in 12 months. The ability to yield resting spores within host carcasses remained unchanged, and the probability of resting spore formation increased with the conidial concentrations that infect aphids. Therefore, cryopreservation at -80 degrees C exerted a marginal impact on formulation and pathogenicity of P. nouryi and can substitute for costly liquid nitrogen storage in routine laboratory studies. The potential of the formulation in aphid biocontrol can be maintained although there is a risk of losing fungal sporulation ability in long-term preservation. PMID:25115115

  2. INTRODUCTION: Intracellular pathogens, which include viruses and some bacteria,

    E-print Network

    Napp, Nils

    mechanisms to detect and disable pathogens. RATIONALE: We hypothesized that one method of pathogen detection, coxsackievirus, entero- virus, and the facultative cytosolic bacteria Salmonella--but not enveloped respiratory

  3. The Genome of the Obligate Intracellular Parasite Trachipleistophora hominis: New Insights into Microsporidian Genome Dynamics and Reductive Evolution

    PubMed Central

    Heinz, Eva; Williams, Tom A.; Nakjang, Sirintra; Noël, Christophe J.; Swan, Daniel C.; Goldberg, Alina V.; Harris, Simon R.; Weinmaier, Thomas; Markert, Stephanie; Becher, Dörte; Bernhardt, Jörg; Dagan, Tal; Hacker, Christian; Lucocq, John M.; Schweder, Thomas; Rattei, Thomas; Hall, Neil; Hirt, Robert P.; Embley, T. Martin

    2012-01-01

    The dynamics of reductive genome evolution for eukaryotes living inside other eukaryotic cells are poorly understood compared to well-studied model systems involving obligate intracellular bacteria. Here we present 8.5 Mb of sequence from the genome of the microsporidian Trachipleistophora hominis, isolated from an HIV/AIDS patient, which is an outgroup to the smaller compacted-genome species that primarily inform ideas of evolutionary mode for these enormously successful obligate intracellular parasites. Our data provide detailed information on the gene content, genome architecture and intergenic regions of a larger microsporidian genome, while comparative analyses allowed us to infer genomic features and metabolism of the common ancestor of the species investigated. Gene length reduction and massive loss of metabolic capacity in the common ancestor was accompanied by the evolution of novel microsporidian-specific protein families, whose conservation among microsporidians, against a background of reductive evolution, suggests they may have important functions in their parasitic lifestyle. The ancestor had already lost many metabolic pathways but retained glycolysis and the pentose phosphate pathway to provide cytosolic ATP and reduced coenzymes, and it had a minimal mitochondrion (mitosome) making Fe-S clusters but not ATP. It possessed bacterial-like nucleotide transport proteins as a key innovation for stealing host-generated ATP, the machinery for RNAi, key elements of the early secretory pathway, canonical eukaryotic as well as microsporidian-specific regulatory elements, a diversity of repetitive and transposable elements, and relatively low average gene density. Microsporidian genome evolution thus appears to have proceeded in at least two major steps: an ancestral remodelling of the proteome upon transition to intracellular parasitism that involved reduction but also selective expansion, followed by a secondary compaction of genome architecture in some, but not all, lineages. PMID:23133373

  4. Cryptococcus neoformans Is a Facultative Intracellular Pathogen in Murine Pulmonary Infection

    PubMed Central

    Feldmesser, Marta; Kress, Yvonne; Novikoff, Phyllis; Casadevall, Arturo

    2000-01-01

    To produce chronic infection, microbial pathogens must escape host immune defenses. Infection with the human pathogenic fungus Cryptococcus neoformans is typically chronic. To understand the mechanism by which C. neoformans survives in tissue after the infection of immunocompetent hosts, we systematically studied the course of pulmonary infection in mice by electron microscopy. The macrophage was the primary phagocytic cell at all times of infection, but neutrophils also ingested yeast. Alveolar macrophages rapidly internalized yeast cells after intratracheal infection, and intracellular yeast cells were noted at all times of infection from 2 h through 28 days. However, the proportion of yeast cells in the intracellular and extracellular spaces varied with the time of infection. Early in infection, yeast cells were found predominantly in the intracellular compartment. A shift toward extracellular predominance occurred by 24 h that was accompanied by macrophage cytotoxicity and disruption. Later in infection, intracellular persistence in vivo was associated with replication, residence in a membrane-bound phagosome, polysaccharide accumulation inside cells, and cytotoxicity to macrophages, despite phagolysosomal fusion. Many phagocytic vacuoles with intracellular yeast had discontinuous membranes. Macrophage infection resulted in cells with a distinctive appearance characterized by large numbers of vacuoles filled with polysaccharide antigen. Similar results were observed in vitro using a macrophage-like cell line. Our results show that C. neoformans is a facultative intracellular pathogen in vivo. Furthermore, our observations suggest that C. neoformans occupies a unique niche among the intracellular pathogens whereby survival in phagocytic cells is accompanied by intracellular polysaccharide production. PMID:10858240

  5. Host-Directed Antimicrobial Drugs with Broad-Spectrum Efficacy against Intracellular Bacterial Pathogens

    PubMed Central

    Czy?, Daniel M.; Potluri, Lakshmi-Prasad; Jain-Gupta, Neeta; Riley, Sean P.; Martinez, Juan J.; Steck, Theodore L.; Crosson, Sean; Gabay, Joëlle E.

    2014-01-01

    ABSTRACT We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. PMID:25073644

  6. A Novel Obligate Intracellular Gamma-Proteobacterium Associated with Ixodid Ticks, Diplorickettsia massiliensis, Gen. Nov., Sp. Nov

    PubMed Central

    Mediannikov, Oleg; Sekeyová, Zuzana; Birg, Marie-Laure; Raoult, Didier

    2010-01-01

    Background Obligate intracellular bacteria of arthropods often exhibit a significant role in either human health or arthropod ecology. Methodology/Principal Findings An obligate intracellular gamma-proteobacterium was isolated from the actively questing hard tick Ixodes ricinus using mammalian and amphibian cell lines. Transmission electron microscopy revealed a unique morphology of the bacterium, including intravacuolar localization of bacteria grouped predominantly in pairs and internal structures composed of electron-dense crystal-like structures and regular multilayer sheath-like structures. The isolate 20B was characterized to determine its taxonomic position using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that this strain belongs to the family Coxiellaceae, order Legionellales of Gamma-proteobacteria, and the closest relatives are different Rickettsiella spp. The level of 16S rRNA gene sequence similarity between strain 20B and other recognized species of the family was below 94.5%. Partial sequences of the rpoB, parC and ftsY genes confirmed the phylogenetic position of the new isolate. The G+C content estimated on the basis of whole genome analysis of strain 20B was 37.88%. On the basis of its phenotypic and genotypic properties, together with phylogenetic distinctiveness, we propose that strain 20B to be classified in the new genus Diplorickettsia as the type strain of a novel species named Diplorickettsia massiliensis sp. nov. Conclusions/Significance Considering the source of its isolation (hard tick, often biting humans) the role of this bacterium in the pathology of humans, animals and ticks should be further investigated. PMID:20644718

  7. Directed antigen delivery as a vaccine strategy for an intracellular bacterial pathogen

    NASA Astrophysics Data System (ADS)

    Bouwer, H. G. Archie; Alberti-Segui, Christine; Montfort, Megan J.; Berkowitz, Nathan D.; Higgins, Darren E.

    2006-03-01

    We have developed a vaccine strategy for generating an attenuated strain of an intracellular bacterial pathogen that, after uptake by professional antigen-presenting cells, does not replicate intracellularly and is readily killed. However, after degradation of the vaccine strain within the phagolysosome, target antigens are released into the cytosol for endogenous processing and presentation for stimulation of CD8+ effector T cells. Applying this strategy to the model intracellular pathogen Listeria monocytogenes, we show that an intracellular replication-deficient vaccine strain is cleared rapidly in normal and immunocompromised animals, yet antigen-specific CD8+ effector T cells are stimulated after immunization. Furthermore, animals immunized with the intracellular replication-deficient vaccine strain are resistant to lethal challenge with a virulent WT strain of L. monocytogenes. These studies suggest a general strategy for developing safe and effective, attenuated intracellular replication-deficient vaccine strains for stimulation of protective immune responses against intracellular bacterial pathogens. CD8+ T cell | replication-deficient | Listeria monocytogenes

  8. Intracellular recognition of pathogens and autophagy as an innate immune host defence.

    PubMed

    Yano, Tamaki; Kurata, Shoichiro

    2011-08-01

    Pathogen recognition is the first and crucial step in innate immunity. Molecular families involved in the recognition of pathogens and activation of the innate immune responses in immunoreactive cells include the Toll-like receptor family in mammals and the peptidoglycan recognition protein (PGRP) family in Drosophila, which sense microorganisms in an extracellular or luminal compartment. Other emerging families are the intracellular recognition molecules for bacteria, such as nucleotide binding and oligomerization domain-like receptors in mammals and PGRP--LE in Drosophila, several of which have been shown to detect structures of bacterial peptidoglycan in the host cell cytosol. Exciting advances in recent studies on autophagy indicate that macroautophagy (referred to here as autophagy) is selectively induced by intracellular recognition molecules and has a crucial role in the elimination of intracellular pathogens, including bacteria, viruses and parasites. This review discusses recent studies related to intracellular recognition molecules and innate immune responses to intracellular pathogens, and highlights the role of autophagy in innate immunity. PMID:21729928

  9. Intracellular recognition of pathogens and autophagy as an innate immune host defence

    PubMed Central

    Yano, Tamaki; Kurata, Shoichiro

    2011-01-01

    Pathogen recognition is the first and crucial step in innate immunity. Molecular families involved in the recognition of pathogens and activation of the innate immune responses in immunoreactive cells include the Toll-like receptor family in mammals and the peptidoglycan recognition protein (PGRP) family in Drosophila, which sense microorganisms in an extracellular or luminal compartment. Other emerging families are the intracellular recognition molecules for bacteria, such as nucleotide binding and oligomerization domain-like receptors in mammals and PGRP–LE in Drosophila, several of which have been shown to detect structures of bacterial peptidoglycan in the host cell cytosol. Exciting advances in recent studies on autophagy indicate that macroautophagy (referred to here as autophagy) is selectively induced by intracellular recognition molecules and has a crucial role in the elimination of intracellular pathogens, including bacteria, viruses and parasites. This review discusses recent studies related to intracellular recognition molecules and innate immune responses to intracellular pathogens, and highlights the role of autophagy in innate immunity. PMID:21729928

  10. Intracellular Pathogens within Alveolar Macrophages in a Patient with HIV Infection: Diagnostic Challenge

    PubMed Central

    Shinha, Takashi; Badem, Olga

    2015-01-01

    In HIV-infected individuals, macrophages, the key defense effector cells, manifest defective activity in their interactions with a wide variety of opportunistic pathogens, including fungi and protozoa. Understanding the morphological characteristics of intracellular opportunistic pathogens in addition to their pathogenesis is of critical importance to provide optimal therapy, thereby decreasing morbidity and mortality in HIV-infected patients. We herein present a case of disseminated histoplasmosis confused with disseminated visceral leishmaniasis in an HIV-infected individual from Guyana who developed intracellular organisms within alveolar macrophages. PMID:25874069

  11. Evolution to a Chronic Disease Niche Correlates with Increased Sensitivity to Tryptophan Availability for the Obligate Intracellular Bacterium Chlamydia pneumoniae

    PubMed Central

    Huston, Wilhelmina M.; Barker, Christopher J.; Chacko, Anu

    2014-01-01

    The chlamydiae are obligate intracellular parasites that have evolved specific interactions with their various hosts and host cell types to ensure their successful survival and consequential pathogenesis. The species Chlamydia pneumoniae is ubiquitous, with serological studies showing that most humans are infected at some stage in their lifetime. While most human infections are asymptomatic, C. pneumoniae can cause more-severe respiratory disease and pneumonia and has been linked to chronic diseases such as asthma, atherosclerosis, and even Alzheimer's disease. The widely dispersed animal-adapted C. pneumoniae strains cause an equally wide range of diseases in their hosts. It is emerging that the ability of C. pneumoniae to survive inside its target cells, including evasion of the host's immune attack mechanisms, is linked to the acquisition of key metabolites. Tryptophan and arginine are key checkpoint compounds in this host-parasite battle. Interestingly, the animal strains of C. pneumoniae have a slightly larger genome, enabling them to cope better with metabolite restrictions. It therefore appears that as the evolutionarily more ancient animal strains have evolved to infect humans, they have selectively become more “susceptible” to the levels of key metabolites, such as tryptophan. While this might initially appear to be a weakness, it allows these human C. pneumoniae strains to exquisitely sense host immune attack and respond by rapidly reverting to a persistent phase. During persistence, they reduce their metabolic levels, halting progression of their developmental cycle, waiting until the hostile external conditions have passed before they reemerge. PMID:24682324

  12. Biological Properties and Cell Tropism of Chp2, a Bacteriophage of the Obligate Intracellular Bacterium Chlamydophila abortus

    PubMed Central

    Everson, J. S.; Garner, S. A.; Fane, B.; Liu, B.-L.; Lambden, P. R.; Clarke, I. N.

    2002-01-01

    A number of bacteriophages belonging to the Microviridae have been described infecting chlamydiae. Phylogenetic studies divide the Chlamydiaceae into two distinct genera, Chlamydia and Chlamydophila, containing three and six different species, respectively. In this work we investigated the biological properties and host range of the recently described bacteriophage Chp2 that was originally discovered in Chlamydophila abortus. The obligate intracellular development cycle of chlamydiae has precluded the development of quantitative approaches to assay bacteriophage infectivity. Thus, we prepared hybridomas secreting monoclonal antibodies (monoclonal antibodies 40 and 55) that were specific for Chp2. We demonstrated that Chp2 binds both C. abortus elementary bodies and reticulate bodies in an enzyme-linked immunosorbent assay. Monoclonal antibodies 40 and 55 also detected bacteriophage Chp2 antigens in chlamydia-infected eukaryotic cells. We used these monoclonal antibodies to monitor the ability of Chp2 to infect all nine species of chlamydiae. Chp2 does not infect members of the genus Chlamydia (C. trachomatis, C. suis, or C. muridarum). Chp2 can infect C. abortus, C. felis, and C. pecorum but is unable to infect other members of this genus, including C. caviae and C. pneumoniae, despite the fact that these chlamydial species support the replication of very closely related bacteriophages. PMID:11976304

  13. Evolution to a chronic disease niche correlates with increased sensitivity to tryptophan availability for the obligate intracellular bacterium Chlamydia pneumoniae.

    PubMed

    Huston, Wilhelmina M; Barker, Christopher J; Chacko, Anu; Timms, Peter

    2014-06-01

    The chlamydiae are obligate intracellular parasites that have evolved specific interactions with their various hosts and host cell types to ensure their successful survival and consequential pathogenesis. The species Chlamydia pneumoniae is ubiquitous, with serological studies showing that most humans are infected at some stage in their lifetime. While most human infections are asymptomatic, C. pneumoniae can cause more-severe respiratory disease and pneumonia and has been linked to chronic diseases such as asthma, atherosclerosis, and even Alzheimer's disease. The widely dispersed animal-adapted C. pneumoniae strains cause an equally wide range of diseases in their hosts. It is emerging that the ability of C. pneumoniae to survive inside its target cells, including evasion of the host's immune attack mechanisms, is linked to the acquisition of key metabolites. Tryptophan and arginine are key checkpoint compounds in this host-parasite battle. Interestingly, the animal strains of C. pneumoniae have a slightly larger genome, enabling them to cope better with metabolite restrictions. It therefore appears that as the evolutionarily more ancient animal strains have evolved to infect humans, they have selectively become more "susceptible" to the levels of key metabolites, such as tryptophan. While this might initially appear to be a weakness, it allows these human C. pneumoniae strains to exquisitely sense host immune attack and respond by rapidly reverting to a persistent phase. During persistence, they reduce their metabolic levels, halting progression of their developmental cycle, waiting until the hostile external conditions have passed before they reemerge. PMID:24682324

  14. Discovery of Putative Small Non-Coding RNAs from the Obligate Intracellular Bacterium Wolbachia pipientis

    PubMed Central

    Woolfit, Megan; Algama, Manjula; Keith, Jonathan M.; McGraw, Elizabeth A.; Popovici, Jean

    2015-01-01

    Wolbachia pipientis is an endosymbiotic bacterium that induces a wide range of effects in its insect hosts, including manipulation of reproduction and protection against pathogens. Little is known of the molecular mechanisms underlying the insect-Wolbachia interaction, though it is likely to be mediated via the secretion of proteins or other factors. There is an increasing amount of evidence that bacteria regulate many cellular processes, including secretion of virulence factors, using small non-coding RNAs (sRNAs), but sRNAs have not previously been described from Wolbachia. We have used two independent approaches, one based on comparative genomics and the other using RNA-Seq data generated for gene expression studies, to identify candidate sRNAs in Wolbachia. We experimentally characterized the expression of one of these candidates in four Wolbachia strains, and showed that it is differentially regulated in different host tissues and sexes. Given the roles played by sRNAs in other host-associated bacteria, the conservation of the candidate sRNAs between different Wolbachia strains, and the sex- and tissue-specific differential regulation we have identified, we hypothesise that sRNAs may play a significant role in the biology of Wolbachia, and in particular in its interactions with its host. PMID:25739023

  15. Discovery of Putative Small Non-Coding RNAs from the Obligate Intracellular Bacterium Wolbachia pipientis.

    PubMed

    Woolfit, Megan; Algama, Manjula; Keith, Jonathan M; McGraw, Elizabeth A; Popovici, Jean

    2015-01-01

    Wolbachia pipientis is an endosymbiotic bacterium that induces a wide range of effects in its insect hosts, including manipulation of reproduction and protection against pathogens. Little is known of the molecular mechanisms underlying the insect-Wolbachia interaction, though it is likely to be mediated via the secretion of proteins or other factors. There is an increasing amount of evidence that bacteria regulate many cellular processes, including secretion of virulence factors, using small non-coding RNAs (sRNAs), but sRNAs have not previously been described from Wolbachia. We have used two independent approaches, one based on comparative genomics and the other using RNA-Seq data generated for gene expression studies, to identify candidate sRNAs in Wolbachia. We experimentally characterized the expression of one of these candidates in four Wolbachia strains, and showed that it is differentially regulated in different host tissues and sexes. Given the roles played by sRNAs in other host-associated bacteria, the conservation of the candidate sRNAs between different Wolbachia strains, and the sex- and tissue-specific differential regulation we have identified, we hypothesise that sRNAs may play a significant role in the biology of Wolbachia, and in particular in its interactions with its host. PMID:25739023

  16. Directed antigen delivery as a vaccine strategy for an intracellular bacterial pathogen

    E-print Network

    Higgins, Darren

    , such as Myco- bacterium tuberculosis, Salmonella enterica serovar Typhi, Lis- teria monocytogenes (Lm that effectively stimulate protective immune responses yet do not cause disease, especially in immunocompromised is a facultative intracellular bacterial pathogen of humans and animals (7) and has been extensively studied

  17. Histone Methylation by NUE, a Novel Nuclear Effector of the Intracellular Pathogen Chlamydia trachomatis

    Microsoft Academic Search

    Meghan E. Pennini; Stéphanie Perrinet; Alice Dautry-Varsat; Agathe Subtil

    2010-01-01

    Sequence analysis of the genome of the strict intracellular pathogen Chlamydia trachomatis revealed the presence of a SET domain containing protein, proteins that primarily function as histone methyltransferases. In these studies, we demonstrated secretion of this protein via a type III secretion mechanism. During infection, the protein is translocated to the host cell nucleus and associates with chromatin. We therefore

  18. No Effect of Wolbachia on Resistance to Intracellular Infection by Pathogenic Bacteria in Drosophila

    E-print Network

    Lazzaro, Brian

    in Drosophila melanogaster Susan M. Rottschaefer*, Brian P. Lazzaro Department of Entomology, Cornell University with the endosymbiotic bacterium Wolbachia pipientis confers Drosophila melanogaster and other insects with resistance to Intracellular Infection by Pathogenic Bacteria in Drosophila melanogaster. PLoS ONE 7(7): e40500. doi:10

  19. Delivery of host cell-directed therapeutics for intracellular pathogen clearance

    PubMed Central

    Collier, Michael A.; Gallovic, Matthew D.; Peine, Kevin J.; Duong, Anthony D.; Bachelder, Eric M.; Gunn, John S.; Schlesinger, Larry S.; Ainslie, Kristy M.

    2014-01-01

    Intracellular pathogens present a major health risk because of their innate ability to evade clearance. Their location within host cells and ability to react to the host environment by mutation or transcriptional changes often enables survival mechanisms to resist standard therapies. Host-directed drugs do not target the pathogen, minimizing the potential development of drug resistance; however, they can be difficult to deliver efficiently to intracellular sites. Vehicle delivery of host-mediated response drugs not only improves drug distribution and toxicity profiles, but can reduce the total amount of drug necessary to clear infection. In this article, we will review some host-directed drugs and current drug delivery techniques that can be used to efficiently clear intracellular infections. PMID:24134600

  20. Is Brucella abortus a facultative intracellular pathogen with mitochondria-like activity?

    PubMed

    Ramírez-Romero, R

    1998-07-01

    Brucella abortus is the agent of bovine brucellosis, a zoonotic disease of worldwide importance. In latently infected humans and animals, acute disease may recur under conditions that decrease the host resistance. This bacterium is considered to be a facultative intracellular pathogen. However, its pathogenic attributes appear reduced in comparison with other Gram-negative pathogens. It has been recognized that B. abortus and other Brucella species reach their intracellular location inside the rough endoplasmic reticulum (RER) of placental trophoblasts and other nonphagocytic epithelial cells. This location is the limiting step for their replication and is in contrast to their intraphagosomal survival and growth in macrophages. To reach the RER, Brucella may be handled as another cellular organelle, like mitochondria. Furthermore, because of its inherent morphological and physiological characteristics, this alpha Proteobacteria may display here some mitochondria-like functions. Finally, external signals mediated by the host hormones and/or cytokines may turn this weak endosymbiotic relationship into a pathological one. PMID:9881835

  1. Characterization of an Obligate Intracellular Bacterium in the Midgut Epithelium of the Bulrush Bug Chilacis typhae (Heteroptera, Lygaeidae, Artheneinae)?

    PubMed Central

    Kuechler, Stefan Martin; Dettner, Konrad; Kehl, Siegfried

    2011-01-01

    Many members of the suborder Heteroptera have symbiotic bacteria, which are usually found extracellularly in specific sacs or tubular outgrowths of the midgut or intracellularly in mycetomes. In this study, we describe the second molecular characterization of a symbiotic bacterium in a monophagous, seed-sucking stink bug of the family Lygaeidae (sensu stricto). Chilacis typhae possesses at the end of the first section of the midgut a structure which is composed of circularly arranged, strongly enlarged midgut epithelial cells. It is filled with an intracellular endosymbiont. This “mycetocytic belt” might represent an evolutionarily intermediate stage of the usual symbiotic structures found in stink bugs. Phylogenetic analysis based on the 16S rRNA and the groEL genes showed that the bacterium belongs to the Gammaproteobacteria, and it revealed a phylogenetic relationship with a secondary bacterial endosymbiont of Cimex lectularius and free-living plant pathogens such as Pectobacterium and Dickeya. The distribution and ultrastructure of the rod-shaped Chilacis endosymbiont were studied in adults and nymph stages using fluorescence in situ hybridization (FISH) and electron microscopy. The detection of symbionts at the anterior poles of developing eggs indicates that endosymbionts are transmitted vertically. A new genus and species name, “Candidatus Rohrkolberia cinguli,” is proposed for this newly characterized clade of symbiotic bacteria. PMID:21378044

  2. Nitric Oxide-Mediated Intracellular Growth Restriction of Pathogenic Rhodococcus equi Can Be Prevented by Iron?

    PubMed Central

    von Bargen, Kristine; Wohlmann, Jens; Taylor, Gregory Alan; Utermöhlen, Olaf; Haas, Albert

    2011-01-01

    Rhodococcus equi is an intracellular pathogen which causes pneumonia in young horses and in immunocompromised humans. R. equi arrests phagosome maturation in macrophages at a prephagolysosome stage and grows inside a privileged compartment. Here, we show that, in murine macrophages activated with gamma interferon and lipopolysaccharide, R. equi does not multiply but stays viable for at least 24 h. Whereas infection control of other intracellular pathogens by activated macrophages is executed by enhanced phagosome acidification or phagolysosome formation, by autophagy or by the interferon-inducible GTPase Irgm1, none of these mechanisms seems to control R. equi infection. Growth control by macrophage activation is fully mimicked by treatment of resting macrophages with nitric oxide donors, and inhibition of bacterial multiplication by either activation or nitric oxide donors is annihilated by cotreatment of infected macrophages with ferrous sulfate. Transcriptional analysis of the R. equi iron-regulated gene iupT demonstrates that intracellular R. equi encounters iron stress in activated, but not in resting, macrophages and that this stress is relieved by extracellular addition of ferrous sulfate. Our results suggest that nitric oxide is central to the restriction of bacterial access to iron in activated macrophages. PMID:21383050

  3. Genome Sequence of Rickettsia bellii Illuminates the Role of Amoebae in Gene Exchanges between Intracellular Pathogens

    PubMed Central

    Ogata, Hiroyuki; La Scola, Bernard; Audic, Stéphane; Renesto, Patricia; Blanc, Guillaume; Robert, Catherine; Fournier, Pierre-Edouard; Claverie, Jean-Michel; Raoult, Didier

    2006-01-01

    The recently sequenced Rickettsia felis genome revealed an unexpected plasmid carrying several genes usually associated with DNA transfer, suggesting that ancestral rickettsiae might have been endowed with a conjugation apparatus. Here we present the genome sequence of Rickettsia bellii, the earliest diverging species of known rickettsiae. The 1,552,076 base pair–long chromosome does not exhibit the colinearity observed between other rickettsia genomes, and encodes a complete set of putative conjugal DNA transfer genes most similar to homologues found in Protochlamydia amoebophila UWE25, an obligate symbiont of amoebae. The genome exhibits many other genes highly similar to homologues in intracellular bacteria of amoebae. We sought and observed sex pili-like cell surface appendages for R. bellii. We also found that R. bellii very efficiently multiplies in the nucleus of eukaryotic cells and survives in the phagocytic amoeba, Acanthamoeba polyphaga. These results suggest that amoeba-like ancestral protozoa could have served as a genetic “melting pot” where the ancestors of rickettsiae and other bacteria promiscuously exchanged genes, eventually leading to their adaptation to the intracellular lifestyle within eukaryotic cells. PMID:16703114

  4. Comparative Genomics Suggests that the Fungal Pathogen Pneumocystis Is an Obligate Parasite Scavenging Amino Acids from Its Host's Lungs

    PubMed Central

    Hauser, Philippe M.; Burdet, Frédéric X.; Cissé, Ousmane H.; Keller, Laurent; Taffé, Patrick; Sanglard, Dominique; Pagni, Marco

    2010-01-01

    Pneumocystis jirovecii is a fungus causing severe pneumonia in immuno-compromised patients. Progress in understanding its pathogenicity and epidemiology has been hampered by the lack of a long-term in vitro culture method. Obligate parasitism of this pathogen has been suggested on the basis of various features but remains controversial. We analysed the 7.0 Mb draft genome sequence of the closely related species Pneumocystis carinii infecting rats, which is a well established experimental model of the disease. We predicted 8’085 (redundant) peptides and 14.9% of them were mapped onto the KEGG biochemical pathways. The proteome of the closely related yeast Schizosaccharomyces pombe was used as a control for the annotation procedure (4’974 genes, 14.1% mapped). About two thirds of the mapped peptides of each organism (65.7% and 73.2%, respectively) corresponded to crucial enzymes for the basal metabolism and standard cellular processes. However, the proportion of P. carinii genes relative to those of S. pombe was significantly smaller for the “amino acid metabolism” category of pathways than for all other categories taken together (40 versus 114 against 278 versus 427, P<0.002). Importantly, we identified in P. carinii only 2 enzymes specifically dedicated to the synthesis of the 20 standard amino acids. By contrast all the 54 enzymes dedicated to this synthesis reported in the KEGG atlas for S. pombe were detected upon reannotation of S. pombe proteome (2 versus 54 against 278 versus 427, P<0.0001). This finding strongly suggests that species of the genus Pneumocystis are scavenging amino acids from their host's lung environment. Consequently, they would have no form able to live independently from another organism, and these parasites would be obligate in addition to being opportunistic. These findings have implications for the management of patients susceptible to P. jirovecii infection given that the only source of infection would be other humans. PMID:21188143

  5. Comparative Genome Analysis of Wheat Blue Dwarf Phytoplasma, an Obligate Pathogen That Causes Wheat Blue Dwarf Disease in China

    PubMed Central

    Chen, Wang; Li, Yan; Wang, Qiang; Wang, Nan; Wu, Yunfeng

    2014-01-01

    Wheat blue dwarf (WBD) disease is an important disease that has caused heavy losses in wheat production in northwestern China. This disease is caused by WBD phytoplasma, which is transmitted by Psammotettix striatus. Until now, no genome information about WBD phytoplasma has been published, seriously restricting research on this obligate pathogen. In this paper, we report a new sequencing and assembling strategy for phytoplasma genome projects. This strategy involves differential centrifugation, pulsed-field gel electrophoresis, whole genome amplification, shotgun sequencing, de novo assembly, screening of contigs from phytoplasma and the connection of phytoplasma contigs. Using this scheme, the WBD phytoplasma draft genome was obtained. It was comprised of six contigs with a total size of 611,462 bp, covering ?94% of the chromosome. Five-hundred-twenty-five protein-coding genes, two operons for rRNA genes and 32 tRNA genes were identified. Comparative genome analyses between WBD phytoplasma and other phytoplasmas were subsequently carried out. The results showed that extensive arrangements and inversions existed among the WBD, OY-M and AY-WB phytoplasma genomes. Most protein-coding genes in WBD phytoplasma were found to be homologous to genes from other phytoplasmas; only 22 WBD-specific genes were identified. KEGG pathway analysis indicated that WBD phytoplasma had strongly reduced metabolic capabilities. However, 46 transporters were identified, which were involved with dipeptides/oligopeptides, spermidine/putrescine, cobalt and Mn/Zn transport, and so on. A total of 37 secreted proteins were encoded in the WBD phytoplasma chromosome and plasmids. Of these, three secreted proteins were similar to the reported phytoplasma virulence factors TENGU, SAP11 and SAP54. In addition, WBD phytoplasma possessed several proteins that were predicted to play a role in its adaptation to diverse environments. These results will provide clues for research on the pathogenic mechanisms of WBD phytoplasma and will also provide a perspective about the genome sequencing of other phytoplasmas and obligate organisms. PMID:24798075

  6. Histone methylation by NUE, a novel nuclear effector of the intracellular pathogen Chlamydia trachomatis.

    PubMed

    Pennini, Meghan E; Perrinet, Stéphanie; Dautry-Varsat, Alice; Subtil, Agathe

    2010-01-01

    Sequence analysis of the genome of the strict intracellular pathogen Chlamydia trachomatis revealed the presence of a SET domain containing protein, proteins that primarily function as histone methyltransferases. In these studies, we demonstrated secretion of this protein via a type III secretion mechanism. During infection, the protein is translocated to the host cell nucleus and associates with chromatin. We therefore named the protein nuclear effector (NUE). Expression of NUE in mammalian cells by transfection reconstituted nuclear targeting and chromatin association. In vitro methylation assays confirmed NUE is a histone methyltransferase that targets histones H2B, H3 and H4 and itself (automethylation). Mutants deficient in automethylation demonstrated diminished activity towards histones suggesting automethylation functions to enhance enzymatic activity. Thus, NUE is secreted by Chlamydia, translocates to the host cell nucleus and has enzymatic activity towards eukaryotic substrates. This work is the first description of a bacterial effector that directly targets mammalian histones. PMID:20657819

  7. Histone Methylation by NUE, a Novel Nuclear Effector of the Intracellular Pathogen Chlamydia trachomatis

    PubMed Central

    Pennini, Meghan E.; Perrinet, Stéphanie; Dautry-Varsat, Alice; Subtil, Agathe

    2010-01-01

    Sequence analysis of the genome of the strict intracellular pathogen Chlamydia trachomatis revealed the presence of a SET domain containing protein, proteins that primarily function as histone methyltransferases. In these studies, we demonstrated secretion of this protein via a type III secretion mechanism. During infection, the protein is translocated to the host cell nucleus and associates with chromatin. We therefore named the protein nuclear effector (NUE). Expression of NUE in mammalian cells by transfection reconstituted nuclear targeting and chromatin association. In vitro methylation assays confirmed NUE is a histone methyltransferase that targets histones H2B, H3 and H4 and itself (automethylation). Mutants deficient in automethylation demonstrated diminished activity towards histones suggesting automethylation functions to enhance enzymatic activity. Thus, NUE is secreted by Chlamydia, translocates to the host cell nucleus and has enzymatic activity towards eukaryotic substrates. This work is the first description of a bacterial effector that directly targets mammalian histones. PMID:20657819

  8. Search for MicroRNAs Expressed by Intracellular Bacterial Pathogens in Infected Mammalian Cells

    PubMed Central

    Furuse, Yuki; Finethy, Ryan; Saka, Hector A.; Xet-Mull, Ana M.; Sisk, Dana M.; Smith, Kristen L. Jurcic; Lee, Sunhee; Coers, Jörn; Valdivia, Raphael H.; Tobin, David M.; Cullen, Bryan R.

    2014-01-01

    MicroRNAs are expressed by all multicellular organisms and play a critical role as post-transcriptional regulators of gene expression. Moreover, different microRNA species are known to influence the progression of a range of different diseases, including cancer and microbial infections. A number of different human viruses also encode microRNAs that can attenuate cellular innate immune responses and promote viral replication, and a fungal pathogen that infects plants has recently been shown to express microRNAs in infected cells that repress host cell immune responses and promote fungal pathogenesis. Here, we have used deep sequencing of total expressed small RNAs, as well as small RNAs associated with the cellular RNA-induced silencing complex RISC, to search for microRNAs that are potentially expressed by intracellular bacterial pathogens and translocated into infected animal cells. In the case of Legionella and Chlamydia and the two mycobacterial species M. smegmatis and M. tuberculosis, we failed to detect any bacterial small RNAs that had the characteristics expected for authentic microRNAs, although large numbers of small RNAs of bacterial origin could be recovered. However, a third mycobacterial species, M. marinum, did express an ?23-nt small RNA that was bound by RISC and derived from an RNA stem-loop with the characteristics expected for a pre-microRNA. While intracellular expression of this candidate bacterial microRNA was too low to effectively repress target mRNA species in infected cultured cells in vitro, artificial overexpression of this potential bacterial pre-microRNA did result in the efficient repression of a target mRNA. This bacterial small RNA therefore represents the first candidate microRNA of bacterial origin. PMID:25184567

  9. Host-Pathogen Checkpoints and Population Bottlenecks in Persistent and Intracellular Uropathogenic E. coli Bladder Infection

    PubMed Central

    Hannan, Thomas J.; Totsika, Makrina; Mansfield, Kylie J.; Moore, Kate H.; Schembri, Mark A.; Hultgren, Scott J.

    2013-01-01

    Bladder infections affect millions of people yearly, and recurrent symptomatic infections (cystitis) are very common. The rapid increase in infections caused by multi-drug resistant uropathogens threatens to make recurrent cystitis an increasingly troubling public health concern. Uropathogenic E. coli (UPEC) cause the vast majority of bladder infections. Upon entry into the lower urinary tract, UPEC face obstacles to colonization that constitute population bottlenecks, reducing diversity and selecting for fit clones. A critical mucosal barrier to bladder infection is the epithelium (urothelium). UPEC bypass this barrier when they invade urothelial cells and form intracellular bacterial communities (IBCs), a process which requires type 1 pili. IBCs are transient in nature, occurring primarily during acute infection. Chronic bladder infection is common and can be either latent, in the form of the Quiescent Intracellular Reservoir (QIR), or active, in the form of asymptomatic bacteriuria (ASB/ABU) or chronic cystitis. In mice, the fate of bladder infection: QIR, ASB, or chronic cystitis, is determined within the first 24 hours of infection and constitutes a putative host-pathogen mucosal checkpoint that contributes to susceptibility to recurrent cystitis. Knowledge of these checkpoints and bottlenecks is critical for our understanding of bladder infection and efforts to devise novel therapeutic strategies. PMID:22404313

  10. A novel methyltransferase from the intracellular pathogen Plasmodiophora brassicae methylates salicylic acid.

    PubMed

    Ludwig-Müller, Jutta; Jülke, Sabine; Geiß, Kathleen; Richter, Franziska; Mithöfer, Axel; Šola, Ivana; Rusak, Gordana; Keenan, Sandi; Bulman, Simon

    2015-05-01

    The obligate biotrophic pathogen Plasmodiophora brassicae causes clubroot disease in Arabidopsis thaliana, which is characterized by large root galls. Salicylic acid (SA) production is a defence response in plants, and its methyl ester is involved in systemic signalling. Plasmodiophora brassicae seems to suppress plant defence reactions, but information on how this is achieved is scarce. Here, we profile the changes in SA metabolism during Arabidopsis clubroot disease. The accumulation of SA and the emission of methylated SA (methyl salicylate, MeSA) were observed in P.?brassicae-infected Arabidopsis 28 days after inoculation. There is evidence that MeSA is transported from infected roots to the upper plant. Analysis of the mutant Atbsmt1, deficient in the methylation of SA, indicated that the Arabidopsis SA methyltransferase was not responsible for alterations in clubroot symptoms. We found that P.?brassicae possesses a methyltransferase (PbBSMT) with homology to plant methyltransferases. The PbBSMT gene is maximally transcribed when SA production is highest. By heterologous expression and enzymatic analyses, we showed that PbBSMT can methylate SA, benzoic and anthranilic acids. PMID:25135243

  11. Silencing of Host Cell CYBB Gene Expression by the Nuclear Effector AnkA of the Intracellular Pathogen Anaplasma phagocytophilum

    Microsoft Academic Search

    Jose C. Garcia-Garcia; Kristen E. Rennoll-Bankert; Shaaretha Pelly; Aaron M. Milstone; J. Stephen Dumler

    2009-01-01

    Coevolution of intracellular bacterial pathogens and their host cells resulted in the appearance of effector molecules that when translocated into the host cell modulate its function, facilitating bacterial survival within the hostile host environment. Some of these effectors interact with host chromatin and other nuclear compo- nents. In this report, we show that the AnkA protein of Anaplasma phagocytophilum, which

  12. Functional Characterization of the Incomplete Phosphotransferase System (PTS) of the Intracellular Pathogen Brucella melitensis

    PubMed Central

    Dozot, Marie; Poncet, Sandrine; Nicolas, Cécile; Copin, Richard; Bouraoui, Houda; Mazé, Alain; Deutscher, Josef; De Bolle, Xavier; Letesson, Jean-Jacques

    2010-01-01

    Background In many bacteria, the phosphotransferase system (PTS) is a key player in the regulation of the assimilation of alternative carbon sources notably through catabolic repression. The intracellular pathogens Brucella spp. possess four PTS proteins (EINtr, NPr, EIIANtr and an EIIA of the mannose family) but no PTS permease suggesting that this PTS might serve only regulatory functions. Methodology/Principal Findings In vitro biochemical analyses and in vivo detection of two forms of EIIANtr (phosphorylated or not) established that the four PTS proteins of Brucella melitensis form a functional phosphorelay. Moreover, in vitro the protein kinase HprK/P phosphorylates NPr on a conserved serine residue, providing an additional level of regulation to the B. melitensis PTS. This kinase activity was inhibited by inorganic phosphate and stimulated by fructose-1,6 bisphosphate. The genes encoding HprK/P, an EIIAMan-like protein and NPr are clustered in a locus conserved among ?-proteobacteria and also contain the genes for the crucial two-component system BvrR-BvrS. RT-PCR revealed a transcriptional link between these genes suggesting an interaction between PTS and BvrR-BvrS. Mutations leading to the inactivation of EINtr or NPr significantly lowered the synthesis of VirB proteins, which form a type IV secretion system. These two mutants also exhibit a small colony phenotype on solid media. Finally, interaction partners of PTS proteins were identified using a yeast two hybrid screen against the whole B. melitensis ORFeome. Both NPr and HprK/P were shown to interact with an inorganic pyrophosphatase and the EIIAMan-like protein with the E1 component (SucA) of 2-oxoglutarate dehydrogenase. Conclusions/Significance The B. melitensis can transfer the phosphoryl group from PEP to the EIIAs and a link between the PTS and the virulence of this organism could be established. Based on the protein interaction data a preliminary model is proposed in which this regulatory PTS coordinates also C and N metabolism. PMID:20844759

  13. The Role of the Francisella Tularensis Pathogenicity Island in Type VI Secretion, Intracellular Survival, and Modulation of Host Cell Signaling

    PubMed Central

    Bröms, Jeanette E.; Sjöstedt, Anders; Lavander, Moa

    2010-01-01

    Francisella tularensis is a highly virulent gram-negative intracellular bacterium that causes the zoonotic disease tularemia. Essential for its virulence is the ability to multiply within host cells, in particular monocytic cells. The bacterium has developed intricate means to subvert host immune mechanisms and thereby facilitate its intracellular survival by preventing phagolysosomal fusion followed by escape into the cytosol, where it multiplies. Moreover, it targets and manipulates numerous host cell signaling pathways, thereby ameliorating the otherwise bactericidal capacity. Many of the underlying molecular mechanisms still remain unknown but key elements, directly or indirectly responsible for many of the aforementioned mechanisms, rely on the expression of proteins encoded by the Francisella pathogenicity island (FPI), suggested to constitute a type VI secretion system. We here describe the current knowledge regarding the components of the FPI and the roles that have been ascribed to them. PMID:21687753

  14. A Rickettsia Genome Overrun by Mobile Genetic Elements Provides Insight into the Acquisition of Genes Characteristic of an Obligate Intracellular Lifestyle

    PubMed Central

    Joardar, Vinita; Williams, Kelly P.; Driscoll, Timothy; Hostetler, Jessica B.; Nordberg, Eric; Shukla, Maulik; Walenz, Brian; Hill, Catherine A.; Nene, Vishvanath M.; Azad, Abdu F.; Sobral, Bruno W.; Caler, Elisabet

    2012-01-01

    We present the draft genome for the Rickettsia endosymbiont of Ixodes scapularis (REIS), a symbiont of the deer tick vector of Lyme disease in North America. Among Rickettsia species (Alphaproteobacteria: Rickettsiales), REIS has the largest genome sequenced to date (>2 Mb) and contains 2,309 genes across the chromosome and four plasmids (pREIS1 to pREIS4). The most remarkable finding within the REIS genome is the extraordinary proliferation of mobile genetic elements (MGEs), which contributes to a limited synteny with other Rickettsia genomes. In particular, an integrative conjugative element named RAGE (for Rickettsiales amplified genetic element), previously identified in scrub typhus rickettsiae (Orientia tsutsugamushi) genomes, is present on both the REIS chromosome and plasmids. Unlike the pseudogene-laden RAGEs of O. tsutsugamushi, REIS encodes nine conserved RAGEs that include F-like type IV secretion systems similar to that of the tra genes encoded in the Rickettsia bellii and R. massiliae genomes. An unparalleled abundance of encoded transposases (>650) relative to genome size, together with the RAGEs and other MGEs, comprise ?35% of the total genome, making REIS one of the most plastic and repetitive bacterial genomes sequenced to date. We present evidence that conserved rickettsial genes associated with an intracellular lifestyle were acquired via MGEs, especially the RAGE, through a continuum of genomic invasions. Robust phylogeny estimation suggests REIS is ancestral to the virulent spotted fever group of rickettsiae. As REIS is not known to invade vertebrate cells and has no known pathogenic effects on I. scapularis, its genome sequence provides insight on the origin of mechanisms of rickettsial pathogenicity. PMID:22056929

  15. HIV-1 Vif Versus the APOBEC3 Cytidine Deaminases: An Intracellular Duel Between Pathogen and Host Restriction Factors

    PubMed Central

    Wissing, Silke; Galloway, Nicole L. K.; Greene, Warner C.

    2010-01-01

    The Vif protein of HIV is essential for the effective propagation of this pathogenic retrovirus in vivo. Vif acts by preventing virion encapsidation of two potent antiviral factors, the APOBEC3G and APOBEC3F cytidine deaminases. Decreased encapsidation in part involves Vif-mediated recruitment of a ubiquitin E3 ligase complex that promotes polyubiquitylation and proteasome-mediated degradation of APOBEC3G/F. The resultant decline in intracellular levels of these enzymes leads to decreased encapsidation of APOBECG/F into budding virions. This review discusses recent advances in our understanding of the dynamic interplay of Vif with the antiviral APOBEC3 enzymes. PMID:20538015

  16. In vivo proteomic analysis of the intracellular bacterial pathogen, Francisella tularensis, isolated from mouse spleen

    Microsoft Academic Search

    Susan M. Twine; Nadia C. S. Mykytczuk; Mireille D. Petit; Hua Shen; Anders Sjöstedt; J. Wayne Conlan; John F. Kelly

    2006-01-01

    Understanding the pathogenesis of infectious diseases requires comprehensive knowledge of the proteins expressed by the pathogen during in vivo growth in the host. Proteomics provides the tools for such analyses but the protocols required to purify sufficient quantities of the pathogen from the host organism are currently lacking. Here, we present a rapid immunomagnetic protocol for the separation of Francisella

  17. Coinfection of tick cell lines has variable effects on replication of intracellular bacterial and viral pathogens

    PubMed Central

    Moniuszko, Anna; Rückert, Claudia; Alberdi, M. Pilar; Barry, Gerald; Stevenson, Brian; Fazakerley, John K.; Kohl, Alain; Bell-Sakyi, Lesley

    2014-01-01

    Ticks transmit various human and animal microbial pathogens and may harbour more than one pathogen simultaneously. Both viruses and bacteria can trigger, and may subsequently suppress, vertebrate host and arthropod vector anti-microbial responses. Microbial coinfection of ticks could lead to an advantage or disadvantage for one or more of the microorganisms. In this preliminary study, cell lines derived from the ticks Ixodes scapularis and Ixodes ricinus were infected sequentially with 2 arthropod-borne pathogens, Borrelia burgdorferi s.s., Ehrlichia ruminantium, or Semliki Forest virus (SFV), and the effect of coinfection on the replication of these pathogens was measured. Prior infection of tick cell cultures with the spirochaete B. burgdorferi enhanced subsequent replication of the rickettsial pathogen E. ruminantium whereas addition of spirochaetes to cells infected with E. ruminantium had no effect on growth of the latter. Both prior and subsequent presence of B. burgdorferi also had a positive effect on SFV replication. Presence of E. ruminantium or SFV had no measurable effect on B. burgdorferi growth. In tick cells infected first with E. ruminantium and then with SFV, virus replication was significantly higher across all time points measured (24, 48, 72 h post infection), while presence of the virus had no detectable effect on bacterial growth. When cells were infected first with SFV and then with E. ruminantium, there was no effect on replication of either pathogen. The results of this preliminary study indicate that interplay does occur between different pathogens during infection of tick cells. Further study is needed to determine if this results from direct pathogen–pathogen interaction or from effects on host cell defences, and to determine if these observations also apply in vivo in ticks. If presence of one pathogen in the tick vector results in increased replication of another, this could have implications for disease transmission and incidence. PMID:24685441

  18. Coinfection of tick cell lines has variable effects on replication of intracellular bacterial and viral pathogens.

    PubMed

    Moniuszko, Anna; Rückert, Claudia; Alberdi, M Pilar; Barry, Gerald; Stevenson, Brian; Fazakerley, John K; Kohl, Alain; Bell-Sakyi, Lesley

    2014-06-01

    Ticks transmit various human and animal microbial pathogens and may harbour more than one pathogen simultaneously. Both viruses and bacteria can trigger, and may subsequently suppress, vertebrate host and arthropod vector anti-microbial responses. Microbial coinfection of ticks could lead to an advantage or disadvantage for one or more of the microorganisms. In this preliminary study, cell lines derived from the ticks Ixodes scapularis and Ixodes ricinus were infected sequentially with 2 arthropod-borne pathogens, Borrelia burgdorferi s.s., Ehrlichia ruminantium, or Semliki Forest virus (SFV), and the effect of coinfection on the replication of these pathogens was measured. Prior infection of tick cell cultures with the spirochaete B. burgdorferi enhanced subsequent replication of the rickettsial pathogen E. ruminantium whereas addition of spirochaetes to cells infected with E. ruminantium had no effect on growth of the latter. Both prior and subsequent presence of B. burgdorferi also had a positive effect on SFV replication. Presence of E. ruminantium or SFV had no measurable effect on B. burgdorferi growth. In tick cells infected first with E. ruminantium and then with SFV, virus replication was significantly higher across all time points measured (24, 48, 72h post infection), while presence of the virus had no detectable effect on bacterial growth. When cells were infected first with SFV and then with E. ruminantium, there was no effect on replication of either pathogen. The results of this preliminary study indicate that interplay does occur between different pathogens during infection of tick cells. Further study is needed to determine if this results from direct pathogen-pathogen interaction or from effects on host cell defences, and to determine if these observations also apply in vivo in ticks. If presence of one pathogen in the tick vector results in increased replication of another, this could have implications for disease transmission and incidence. PMID:24685441

  19. TLR-Independent Type I Interferon Induction in Response to an Extracellular Bacterial Pathogen via Intracellular Recognition of Its DNA

    PubMed Central

    Charrel-Dennis, Marie; Latz, Eicke; Halmen, Kristen A.; Trieu-Cuot, Patrick; Fitzgerald, Katherine A.; Kasper, Dennis L.; Golenbock, Douglas T.

    2011-01-01

    SUMMARY Type I interferon (IFN) is an important host defense cytokine against intracellular pathogens, mainly viruses. In assessing IFN production in response to group B streptococcus (GBS), we find that IFN-? was produced by macrophages upon stimulation with both heat-killed and live GBS. Exposure of macrophages to heat-killed GBS activated a Toll-like receptor (TLR)-dependent pathway, whereas live GBS activated a TLR/NOD/RIG-like receptor (RLR)-independent pathway. This latter pathway required bacterial phagocytosis, proteolytic bacterial degradation, and phagolysosomal membrane destruction by GBS pore-forming toxins, leading to the release of bacterial DNA into the cytosol. GBS DNA in the cytosol induced IFN-? production via a pathway dependent on the activation of the serine-threonine kinase TBK1 and phosphorylation of the transcription factor IRF3. Thus, activation of IFN-?/-? production during infection with GBS, commonly considered an extracellular pathogen, appears to result from the interaction of GBS DNA with a putative intracellular DNA sensor or receptor. PMID:19064255

  20. The Equine Antimicrobial Peptide eCATH1 Is Effective against the Facultative Intracellular Pathogen Rhodococcus equi in Mice

    PubMed Central

    Schlusselhuber, Margot; Torelli, Riccardo; Martini, Cecilia; Leippe, Matthias; Cattoir, Vincent; Leclercq, Roland; Laugier, Claire; Grötzinger, Joachim; Sanguinetti, Maurizio

    2013-01-01

    Rhodococcus equi, the causal agent of rhodococcosis, is a major pathogen of foals and is also responsible for severe infections in immunocompromised humans. Of great concern, strains resistant to currently used antibiotics have emerged. As the number of drugs that are efficient in vivo is limited because of the intracellular localization of the bacterium inside macrophages, new active but cell-permeant drugs will be needed in the near future. In the present study, we evaluated, by in vitro and ex vivo experiments, the ability of the alpha-helical equine antimicrobial peptide eCATH1 to kill intracellular bacterial cells. Moreover, the therapeutic potential of the peptide was assessed in experimental rhodococcosis induced in mice, while the in vivo toxicity was evaluated by behavioral and histopathological analysis. The study revealed that eCATH1 significantly reduced the number of bacteria inside macrophages. Furthermore, the bactericidal potential of the peptide was maintained in vivo at doses that appeared to have no visible deleterious effects for the mice even after 7 days of treatment. Indeed, daily subcutaneous injections of 1 mg/kg body weight of eCATH1 led to a significant reduction of the bacterial load in organs comparable to that obtained after treatment with 10 mg/kg body weight of rifampin. Interestingly, the combination of the peptide with rifampin showed a synergistic interaction in both ex vivo and in vivo experiments. These results emphasize the therapeutic potential that eCATH1 represents in the treatment of rhodococcosis. PMID:23817377

  1. The Animal Pathogen-Like Type III Secretion System Is Required for the Intracellular Survival of Burkholderia mallei within J774.2 Macrophages

    Microsoft Academic Search

    Wilson J. Ribot; Ricky L. Ulrich

    2006-01-01

    Burkholderia mallei is a highly infectious gram-negative pathogen and is the causative agent of human and animal glanders. By generating polar mutations (disruption of bsaQ and bsaZ) in the B. mallei ATCC 23344 animal pathogen-like type III secretion system (TTS), we demonstrate that this bacterial protein delivery system is required for intracellular growth of B. mallei in J774.2 cells, formation

  2. Intracellular Growth Is Dependent on Tyrosine Catabolism in the Dimorphic Fungal Pathogen Penicillium marneffei

    PubMed Central

    Boyce, Kylie J.; McLauchlan, Alisha; Schreider, Lena; Andrianopoulos, Alex

    2015-01-01

    During infection, pathogens must utilise the available nutrient sources in order to grow while simultaneously evading or tolerating the host’s defence systems. Amino acids are an important nutritional source for pathogenic fungi and can be assimilated from host proteins to provide both carbon and nitrogen. The hpdA gene of the dimorphic fungus Penicillium marneffei, which encodes an enzyme which catalyses the second step of tyrosine catabolism, was identified as up-regulated in pathogenic yeast cells. As well as enabling the fungus to acquire carbon and nitrogen, tyrosine is also a precursor in the formation of two types of protective melanin; DOPA melanin and pyomelanin. Chemical inhibition of HpdA in P. marneffei inhibits ex vivo yeast cell production suggesting that tyrosine is a key nutrient source during infectious growth. The genes required for tyrosine catabolism, including hpdA, are located in a gene cluster and the expression of these genes is induced in the presence of tyrosine. A gene (hmgR) encoding a Zn(II)2-Cys6 binuclear cluster transcription factor is present within the cluster and is required for tyrosine induced expression and repression in the presence of a preferred nitrogen source. AreA, the GATA-type transcription factor which regulates the global response to limiting nitrogen conditions negatively regulates expression of cluster genes in the absence of tyrosine and is required for nitrogen metabolite repression. Deletion of the tyrosine catabolic genes in the cluster affects growth on tyrosine as either a nitrogen or carbon source and affects pyomelanin, but not DOPA melanin, production. In contrast to other genes of the tyrosine catabolic cluster, deletion of hpdA results in no growth within macrophages. This suggests that the ability to catabolise tyrosine is not required for macrophage infection and that HpdA has an additional novel role to that of tyrosine catabolism and pyomelanin production during growth in host cells. PMID:25812137

  3. Controlling the intracellular fate of cytosolic pathogens A PhD studentship based in the Section of Microbiology, Imperial College London.

    E-print Network

    in research in the broad areas of microbial pathogenesis and microbial adaptation to the host. The Section discovered that the host cell employs septins, a novel component of the host cytoskeleton, to restrict and characterize host and pathogen determinants underlying the intracellular fate of cytosolic bacteria (2

  4. Structure of the virulence-associated protein VapD from the intracellular pathogen Rhodococcus equi

    PubMed Central

    Whittingham, Jean L.; Blagova, Elena V.; Finn, Ciaran E.; Luo, Haixia; Miranda-CasoLuengo, Raúl; Turkenburg, Johan P.; Leech, Andrew P.; Walton, Paul H.; Murzin, Alexey G.; Meijer, Wim G.; Wilkinson, Anthony J.

    2014-01-01

    Rhodococcus equi is a multi-host pathogen that infects a range of animals as well as immune-compromised humans. Equine and porcine isolates harbour a virulence plasmid encoding a homologous family of virulence-associated proteins associated with the capacity of R. equi to divert the normal processes of endosomal maturation, enabling bacterial survival and proliferation in alveolar macrophages. To provide a basis for probing the function of the Vap proteins in virulence, the crystal structure of VapD was determined. VapD is a monomer as determined by multi-angle laser light scattering. The structure reveals an elliptical, compact eight-stranded ?-barrel with a novel strand topology and pseudo-twofold symmetry, suggesting evolution from an ancestral dimer. Surface-associated octyl-?-d-glucoside molecules may provide clues to function. Circular-dichroism spectroscopic analysis suggests that the ?-barrel structure is preceded by a natively disordered region at the N-terminus. Sequence comparisons indicate that the core folds of the other plasmid-encoded virulence-associated proteins from R. equi strains are similar to that of VapD. It is further shown that sequences encoding putative R. equi Vap-like proteins occur in diverse bacterial species. Finally, the functional implications of the structure are discussed in the light of the unique structural features of VapD and its partial structural similarity to other ?-barrel proteins. PMID:25084333

  5. AmiA is a penicillin target enzyme with dual activity in the intracellular pathogen Chlamydia pneumoniae

    PubMed Central

    Klöckner, Anna; Otten, Christian; Derouaux, Adeline; Vollmer, Waldemar; Bühl, Henrike; De Benedetti, Stefania; Münch, Daniela; Josten, Michaele; Mölleken, Katja; Sahl, Hans-Georg; Henrichfreise, Beate

    2014-01-01

    Intracellular Chlamydiaceae do not need to resist osmotic challenges and a functional cell wall was not detected in these pathogens. Nevertheless, a recent study revealed evidence for circular peptidoglycan-like structures in Chlamydiaceae and penicillin inhibits cytokinesis, a phenomenon known as the chlamydial anomaly. Here, by characterizing a cell wall precursor-processing enzyme, we provide insights into the mechanisms underlying this mystery. We show that AmiA from Chlamydia pneumoniae separates daughter cells in an Escherichia coli amidase mutant. Contrary to homologues from free-living bacteria, chlamydial AmiA uses lipid II as a substrate and has dual activity, acting as an amidase and a carboxypeptidase. The latter function is penicillin sensitive and assigned to a penicillin-binding protein motif. Consistent with the lack of a regulatory domain in AmiA, chlamydial CPn0902, annotated as NlpD, is a carboxypeptidase, rather than an amidase activator, which is the case for E. coli NlpD. Functional conservation of AmiA implicates a role in cytokinesis and host response modulation. PMID:24953137

  6. AmiA is a penicillin target enzyme with dual activity in the intracellular pathogen Chlamydia pneumoniae.

    PubMed

    Klöckner, Anna; Otten, Christian; Derouaux, Adeline; Vollmer, Waldemar; Bühl, Henrike; De Benedetti, Stefania; Münch, Daniela; Josten, Michaele; Mölleken, Katja; Sahl, Hans-Georg; Henrichfreise, Beate

    2014-01-01

    Intracellular Chlamydiaceae do not need to resist osmotic challenges and a functional cell wall was not detected in these pathogens. Nevertheless, a recent study revealed evidence for circular peptidoglycan-like structures in Chlamydiaceae and penicillin inhibits cytokinesis, a phenomenon known as the chlamydial anomaly. Here, by characterizing a cell wall precursor-processing enzyme, we provide insights into the mechanisms underlying this mystery. We show that AmiA from Chlamydia pneumoniae separates daughter cells in an Escherichia coli amidase mutant. Contrary to homologues from free-living bacteria, chlamydial AmiA uses lipid II as a substrate and has dual activity, acting as an amidase and a carboxypeptidase. The latter function is penicillin sensitive and assigned to a penicillin-binding protein motif. Consistent with the lack of a regulatory domain in AmiA, chlamydial CPn0902, annotated as NlpD, is a carboxypeptidase, rather than an amidase activator, which is the case for E. coli NlpD. Functional conservation of AmiA implicates a role in cytokinesis and host response modulation. PMID:24953137

  7. Granulocyte macrophage-colony stimulating factor induced Zn sequestration enhances macrophage superoxide and limits intracellular pathogen survival.

    PubMed

    Subramanian Vignesh, Kavitha; Landero Figueroa, Julio A; Porollo, Aleksey; Caruso, Joseph A; Deepe, George S

    2013-10-17

    Macrophages possess numerous mechanisms to combat microbial invasion, including sequestration of essential nutrients, like zinc (Zn). The pleiotropic cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) enhances antimicrobial defenses against intracellular pathogens such as Histoplasma capsulatum, but its mode of action remains elusive. We have found that GM-CSF-activated infected macrophages sequestered labile Zn by inducing binding to metallothioneins (MTs) in a STAT3 and STAT5 transcription-factor-dependent manner. GM-CSF upregulated expression of Zn exporters, Slc30a4 and Slc30a7; the metal was shuttled away from phagosomes and into the Golgi apparatus. This distinctive Zn sequestration strategy elevated phagosomal H? channel function and triggered reactive oxygen species generation by NADPH oxidase. Consequently, H. capsulatum was selectively deprived of Zn, thereby halting replication and fostering fungal clearance. GM-CSF mediated Zn sequestration via MTs in vitro and in vivo in mice and in human macrophages. These findings illuminate a GM-CSF-induced Zn-sequestration network that drives phagocyte antimicrobial effector function. PMID:24138881

  8. Analysis of the Bovine Intracellular Enteric Pathogen Interactome Each year the beef and dairy industries lose more than $330 million because of enteric diseases that cause the death of more than

    E-print Network

    Analysis of the Bovine Intracellular Enteric Pathogen Interactome Each year the beef and dairy weight gain. Understanding how cattle respond to enteric pathogens during acute infection is crucial have developed an in vivo bovine ligated ileal loop model to study bovine response to enteric pathogens

  9. Invasion of the Central Nervous System by Intracellular Bacteria

    PubMed Central

    Drevets, Douglas A.; Leenen, Pieter J. M.; Greenfield, Ronald A.

    2004-01-01

    Infection of the central nervous system (CNS) is a severe and frequently fatal event during the course of many diseases caused by microbes with predominantly intracellular life cycles. Examples of these include the facultative intracellular bacteria Listeria monocytogenes, Mycobacterium tuberculosis, and Brucella and Salmonella spp. and obligate intracellular microbes of the Rickettsiaceae family and Tropheryma whipplei. Unfortunately, the mechanisms used by intracellular bacterial pathogens to enter the CNS are less well known than those used by bacterial pathogens with an extracellular life cycle. The goal of this review is to elaborate on the means by which intracellular bacterial pathogens establish infection within the CNS. This review encompasses the clinical and pathological findings that pertain to the CNS infection in humans and includes experimental data from animal models that illuminate how these microbes enter the CNS. Recent experimental data showing that L. monocytogenes can invade the CNS by more than one mechanism make it a useful model for discussing the various routes for neuroinvasion used by intracellular bacterial pathogens. PMID:15084504

  10. The IFN-?-Inducible GTPase, Irga6, Protects Mice against Toxoplasma gondii but Not against Plasmodium berghei and Some Other Intracellular Pathogens

    Microsoft Academic Search

    Oliver Liesenfeld; Iana Parvanova; Jens Zerrahn; Seong-Ji Han; Frederik Heinrich; Melba Muñoz; Frank Kaiser; Toni Aebischer; Thorsten Buch; Ari Waisman; Gaby Reichmann; Olaf Utermöhlen; Esther von Stebut; Friederike D. von Loewenich; Christian Bogdan; Sabine Specht; Michael Saeftel; Achim Hoerauf; Maria M. Mota; Stephanie Könen-Waisman; Stefan H. E. Kaufmann; Jonathan C. Howard

    2011-01-01

    Clearance of infection with intracellular pathogens in mice involves interferon-regulated GTPases of the IRG protein family. Experiments with mice genetically deficient in members of this family such as Irgm1(LRG-47), Irgm3(IGTP), and Irgd(IRG-47) has revealed a critical role in microbial clearance, especially for Toxoplasma gondii. The in vivo role of another member of this family, Irga6 (IIGP, IIGP1) has been studied

  11. The small GTPase RAB-11 directs polarized exocytosis of the intracellular pathogen N. parisii for fecal-oral transmission from C. elegans.

    PubMed

    Szumowski, Suzannah C; Botts, Michael R; Popovich, John J; Smelkinson, Margery G; Troemel, Emily R

    2014-06-01

    Pathogen exit is a key stage in the spread and propagation of infectious disease, with the fecal-oral route being a common mode of disease transmission. However, it is poorly understood which molecular pathways provide the major modes for intracellular pathogen exit and fecal-oral transmission in vivo. Here, we use the transparent nematode Caenorhabditis elegans to investigate intestinal cell exit and fecal-oral transmission by the natural intracellular pathogen Nematocida parisii, which is a recently identified species of microsporidia. We show that N. parisii exits from polarized host intestinal cells by co-opting the host vesicle trafficking system and escaping into the lumen. Using a genetic screen, we identified components of the host endocytic recycling pathway that are required for N. parisii spore exit via exocytosis. In particular, we show that the small GTPase RAB-11 localizes to apical spores, is required for spore-containing compartments to fuse with the apical plasma membrane, and is required for spore exit. In addition, we find that RAB-11-deficient animals exhibit impaired contagiousness, supporting an in vivo role for this host trafficking factor in microsporidia disease transmission. Altogether, these findings provide an in vivo example of the major mode of exit used by a natural pathogen for disease spread via fecal-oral transmission. PMID:24843160

  12. The small GTPase RAB-11 directs polarized exocytosis of the intracellular pathogen N. parisii for fecal-oral transmission from C. elegans

    PubMed Central

    Szumowski, Suzannah C.; Botts, Michael R.; Popovich, John J.; Smelkinson, Margery G.; Troemel, Emily R.

    2014-01-01

    Pathogen exit is a key stage in the spread and propagation of infectious disease, with the fecal-oral route being a common mode of disease transmission. However, it is poorly understood which molecular pathways provide the major modes for intracellular pathogen exit and fecal-oral transmission in vivo. Here, we use the transparent nematode Caenorhabditis elegans to investigate intestinal cell exit and fecal-oral transmission by the natural intracellular pathogen Nematocida parisii, which is a recently identified species of microsporidia. We show that N. parisii exits from polarized host intestinal cells by co-opting the host vesicle trafficking system and escaping into the lumen. Using a genetic screen, we identified components of the host endocytic recycling pathway that are required for N. parisii spore exit via exocytosis. In particular, we show that the small GTPase RAB-11 localizes to apical spores, is required for spore-containing compartments to fuse with the apical plasma membrane, and is required for spore exit. In addition, we find that RAB-11–deficient animals exhibit impaired contagiousness, supporting an in vivo role for this host trafficking factor in microsporidia disease transmission. Altogether, these findings provide an in vivo example of the major mode of exit used by a natural pathogen for disease spread via fecal-oral transmission. PMID:24843160

  13. Institutional obligation

    SciTech Connect

    Rowan, S.S.; Berwager, S.D. (Bonneville Power Administration, Portland, OR (US))

    1988-01-01

    The institutional obligation is to act to meet primary responsibilities in the face of risks. There are risks involved in taking action, both of a quantifiable and unquantifiable nature. This paper explores weighing the risks, choosing approaches that balance primary obligations with broader ones, and presenting ethical philosophies upon which policies and strategies are based. Federal government organizations and utilities--and Bonneville Power Administration qualifies as both--have a variety of responsibilities to the public they serve. The common responsibility is that of service; for Bonneville the primary responsibility is to serve the energy related needs. It is this primary institutional obligation, as it relates to other responsibilities--and the resulting strategy for handling indoor air quality in Bonneville's new homes program--that this paper examines.

  14. HLA-B27 Modulates Intracellular Growth of Salmonella Pathogenicity Island 2 Mutants and Production of Cytokines in Infected Monocytic U937 Cells

    PubMed Central

    Ge, Shichao; He, Qiushui; Granfors, Kaisa

    2012-01-01

    Background Salmonella enterica serovar Enteritidis PT4 KS8822/88 replicates rapidly in HLA-B27-transfected human monocytic U937 cells. In this process, Salmonella pathogenicity island 2 (SPI-2) genes play a crucial role. Our previous study indicated that 118 Salmonella genes, including 8 SPI-2 genes were affected by HLA-B27 antigen during Salmonella infection of U937 cells. Methods/Principal Findings To further investigate Salmonella replication in HLA-B27-positive U937 monocytic cells, two SPI-2 genes, ssaS and sscA up-regulated most during Salmonella infection of HLA-B27-transfected U937 cells, were mutated by using one-step gene disruption method. Intracellular survival and replication of the mutants in the U937 cells was compared to that of the wild type strain. Surprisingly, the two mutated strains replicated significantly more than the wild type bacteria in HLA-B27-transfected cells. Secretion of tumor necrosis factor alpha (TNF-?) and interleukin 10 (IL-10) was significantly induced during the infection of HLA-B27-transfected U937 cells with the mutants. The results indicated that the certain SPI-2 genes in wild type bacteria suppress Salmonella intracellular growth and production of cytokines in infected HLA-B27-transfected cells. HLA-B27-associated modulation of Salmonella SPI-2 genes and cytokine production may have importance in the persistent infection of the bacteria and the pathogenesis of reactive arthritis. Conclusions The study provides evidence that certain virulence factors of pathogens can reduce the intracellular growth in the host cells. We suggest that the limiting intracellular growth might be a strategy for persistence of bacteria in host cells, keeping a balance between pathogenic growth and pathogenesis. PMID:22470519

  15. Non-coding RNA regulation in pathogenic bacteria located inside eukaryotic cells

    PubMed Central

    Ortega, Álvaro D.; Quereda, Juan J.; Pucciarelli, M. Graciela; García-del Portillo, Francisco

    2014-01-01

    Intracellular bacterial pathogens have evolved distinct lifestyles inside eukaryotic cells. Some pathogens coexist with the infected cell in an obligate intracellular state, whereas others transit between the extracellular and intracellular environment. Adaptation to these intracellular lifestyles is regulated in both space and time. Non-coding small RNAs (sRNAs) are post-transcriptional regulatory molecules that fine-tune important processes in bacterial physiology including cell envelope architecture, intermediate metabolism, bacterial communication, biofilm formation, and virulence. Recent studies have shown production of defined sRNA species by intracellular bacteria located inside eukaryotic cells. The molecules targeted by these sRNAs and their expression dynamics along the intracellular infection cycle remain, however, poorly characterized. Technical difficulties linked to the isolation of “intact” intracellular bacteria from infected host cells might explain why sRNA regulation in these specialized pathogens is still a largely unexplored field. Transition from the extracellular to the intracellular lifestyle provides an ideal scenario in which regulatory sRNAs are intended to participate; so much work must be done in this direction. This review focuses on sRNAs expressed by intracellular bacterial pathogens during the infection of eukaryotic cells, strategies used with these pathogens to identify sRNAs required for virulence, and the experimental technical challenges associated to this type of studies. We also discuss varied techniques for their potential application to study RNA regulation in intracellular bacterial infections. PMID:25429360

  16. Truncated hemoglobin, HbN, is post-translationally modified in Mycobacterium tuberculosis and modulates host-pathogen interactions during intracellular infection.

    PubMed

    Arya, Swati; Sethi, Deepti; Singh, Sandeep; Hade, Mangesh Dattu; Singh, Vijender; Raju, Preeti; Chodisetti, Sathi Babu; Verma, Deepshikha; Varshney, Grish C; Agrewala, Javed N; Dikshit, Kanak L

    2013-10-11

    Mycobacterium tuberculosis (Mtb) is a phenomenally successful human pathogen having evolved mechanisms that allow it to survive within the hazardous environment of macrophages and establish long term, persistent infection in the host against the control of cell-mediated immunity. One such mechanism is mediated by the truncated hemoglobin, HbN, of Mtb that displays a potent O2-dependent nitric oxide dioxygenase activity and protects its host from the toxicity of macrophage-generated nitric oxide (NO). Here we demonstrate for the first time that HbN is post-translationally modified by glycosylation in Mtb and remains localized on the cell membrane and the cell wall. The glycan linkage in the HbN was identified as mannose. The elevated expression of HbN in Mtb and M. smegmatis facilitated their entry within the macrophages as compared with isogenic control cells, and mutation in the glycan linkage of HbN disrupted this effect. Additionally, HbN-expressing cells exhibited higher survival within the THP-1 and mouse peritoneal macrophages, simultaneously increasing the intracellular level of proinflammatory cytokines IL-6 and TNF-? and suppressing the expression of co-stimulatory surface markers CD80 and CD86. These results, thus, suggest the involvement of HbN in modulating the host-pathogen interactions and immune system of the host apart from protecting the bacilli from nitrosative stress inside the activated macrophages, consequently driving cells toward increased infectivity and intracellular survival. PMID:23983123

  17. Genome sequencing of the lizard parasite Leishmania tarentolae reveals loss of genes associated to the intracellular stage of human pathogenic species

    PubMed Central

    Raymond, Frédéric; Boisvert, Sébastien; Roy, Gaétan; Ritt, Jean-François; Légaré, Danielle; Isnard, Amandine; Stanke, Mario; Olivier, Martin; Tremblay, Michel J.; Papadopoulou, Barbara; Ouellette, Marc; Corbeil, Jacques

    2012-01-01

    The Leishmania tarentolae Parrot-TarII strain genome sequence was resolved to an average 16-fold mean coverage by next-generation DNA sequencing technologies. This is the first non-pathogenic to humans kinetoplastid protozoan genome to be described thus providing an opportunity for comparison with the completed genomes of pathogenic Leishmania species. A high synteny was observed between all sequenced Leishmania species. A limited number of chromosomal regions diverged between L. tarentolae and L. infantum, while remaining syntenic to L. major. Globally, >90% of the L. tarentolae gene content was shared with the other Leishmania species. We identified 95 predicted coding sequences unique to L. tarentolae and 250 genes that were absent from L. tarentolae. Interestingly, many of the latter genes were expressed in the intracellular amastigote stage of pathogenic species. In addition, genes coding for products involved in antioxidant defence or participating in vesicular-mediated protein transport were underrepresented in L. tarentolae. In contrast to other Leishmania genomes, two gene families were expanded in L. tarentolae, namely the zinc metallo-peptidase surface glycoprotein GP63 and the promastigote surface antigen PSA31C. Overall, L. tarentolae's gene content appears better adapted to the promastigote insect stage rather than the amastigote mammalian stage. PMID:21998295

  18. Intercellular and intracellular signalling systems that globally control the expression of virulence genes in plant pathogenic bacteria.

    PubMed

    Ham, Jong Hyun

    2013-04-01

    Plant pathogenic bacteria utilize complex signalling systems to control the expression of virulence genes at the cellular level and within populations. Quorum sensing (QS), an important intercellular communication mechanism, is mediated by different types of small molecules, including N-acyl homoserine lactones (AHLs), fatty acids and small proteins. AHL-mediated signalling systems dependent on the LuxI and LuxR family proteins play critical roles in the virulence of a wide range of Gram-negative plant pathogenic bacteria belonging to the Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Xanthomonas spp. and Xylella fastidiosa, members of the Gammaproteobacteria, however, possess QS systems that are mediated by fatty acid-type diffusible signal factors (DSFs). Recent studies have demonstrated that Ax21, a 194-amino-acid protein in Xanthomonas oryzae pv. oryzae, plays dual functions in activating a rice innate immune pathway through binding to the rice XA21 pattern recognition receptor and in regulating bacterial virulence and biofilm formation as a QS signal molecule. In xanthomonads, DSF-mediated QS systems are connected with the signalling pathways mediated by cyclic diguanosine monophosphate (c-di-GMP), which functions as a second messenger for the control of virulence gene expression in these bacterial pathogens. PMID:23186372

  19. TmpL, a Transmembrane Protein Required for Intracellular Redox Homeostasis and Virulence in a Plant and an Animal Fungal Pathogen

    PubMed Central

    Kim, Kwang-Hyung; Willger, Sven D.; Park, Sang-Wook; Puttikamonkul, Srisombat; Grahl, Nora; Cho, Yangrae; Mukhopadhyay, Biswarup; Cramer, Robert A.; Lawrence, Christopher B.

    2009-01-01

    The regulation of intracellular levels of reactive oxygen species (ROS) is critical for developmental differentiation and virulence of many pathogenic fungi. In this report we demonstrate that a novel transmembrane protein, TmpL, is necessary for regulation of intracellular ROS levels and tolerance to external ROS, and is required for infection of plants by the necrotroph Alternaria brassicicola and for infection of mammals by the human pathogen Aspergillus fumigatus. In both fungi, tmpL encodes a predicted hybrid membrane protein containing an AMP-binding domain, six putative transmembrane domains, and an experimentally-validated FAD/NAD(P)-binding domain. Localization and gene expression analyses in A. brassicicola indicated that TmpL is associated with the Woronin body, a specialized peroxisome, and strongly expressed during conidiation and initial invasive growth in planta. A. brassicicola and A. fumigatus ?tmpL strains exhibited abnormal conidiogenesis, accelerated aging, enhanced oxidative burst during conidiation, and hypersensitivity to oxidative stress when compared to wild-type or reconstituted strains. Moreover, A. brassicicola ?tmpL strains, although capable of initial penetration, exhibited dramatically reduced invasive growth on Brassicas and Arabidopsis. Similarly, an A. fumigatus ?tmpL mutant was dramatically less virulent than the wild-type and reconstituted strains in a murine model of invasive aspergillosis. Constitutive expression of the A. brassicicola yap1 ortholog in an A. brassicicola ?tmpL strain resulted in high expression levels of genes associated with oxidative stress tolerance. Overexpression of yap1 in the ?tmpL background complemented the majority of observed developmental phenotypic changes and partially restored virulence on plants. Yap1-GFP fusion strains utilizing the native yap1 promoter exhibited constitutive nuclear localization in the A. brassicicola ?tmpL background. Collectively, we have discovered a novel protein involved in the virulence of both plant and animal fungal pathogens. Our results strongly suggest that dysregulation of oxidative stress homeostasis in the absence of TmpL is the underpinning cause of the developmental and virulence defects observed in these studies. PMID:19893627

  20. Identification of C. burnetii Type IV Secretion Substrates Required for Intracellular Replication and Coxiella-Containing Vacuole Formation

    E-print Network

    Weber, Mary

    2014-05-05

    -negative naturally obligate intracellular pathogen, is the etiological agent of Q fever, a zoonotic disease predominately associated with domestic livestock. The primary route of transmission occurs via inhalation of contaminated aerosols, resulting in an acute..., flu-like illness that is typically self-limiting and readily resolves without antibiotic treatment. However, in rare instances chronic Q fever can develop that results in chronic endocarditis or hepatitis (81). The highly infectious nature...

  1. The Steroid Catabolic Pathway of the Intracellular Pathogen Rhodococcus equi Is Important for Pathogenesis and a Target for Vaccine Development

    PubMed Central

    van der Geize, R.; Grommen, A. W. F.; Hessels, G. I.; Jacobs, A. A. C.; Dijkhuizen, L.

    2011-01-01

    Rhodococcus equi causes fatal pyogranulomatous pneumonia in foals and immunocompromised animals and humans. Despite its importance, there is currently no effective vaccine against the disease. The actinobacteria R. equi and the human pathogen Mycobacterium tuberculosis are related, and both cause pulmonary diseases. Recently, we have shown that essential steps in the cholesterol catabolic pathway are involved in the pathogenicity of M. tuberculosis. Bioinformatic analysis revealed the presence of a similar cholesterol catabolic gene cluster in R. equi. Orthologs of predicted M. tuberculosis virulence genes located within this cluster, i.e. ipdA (rv3551), ipdB (rv3552), fadA6 and fadE30, were identified in R. equi RE1 and inactivated. The ipdA and ipdB genes of R. equi RE1 appear to constitute the ?-subunit and ?-subunit, respectively, of a heterodimeric coenzyme A transferase. Mutant strains RE1?ipdAB and RE1?fadE30, but not RE1?fadA6, were impaired in growth on the steroid catabolic pathway intermediates 4-androstene-3,17-dione (AD) and 3a?-H-4?(3?-propionic acid)-5?-hydroxy-7a?-methylhexahydro-1-indanone (5?-hydroxy-methylhexahydro-1-indanone propionate; 5OH-HIP). Interestingly, RE1?ipdAB and RE1?fadE30, but not RE1?fadA6, also displayed an attenuated phenotype in a macrophage infection assay. Gene products important for growth on 5OH-HIP, as part of the steroid catabolic pathway, thus appear to act as factors involved in the pathogenicity of R. equi. Challenge experiments showed that RE1?ipdAB could be safely administered intratracheally to 2 to 5 week-old foals and oral immunization of foals even elicited a substantial protective immunity against a virulent R. equi strain. Our data show that genes involved in steroid catabolism are promising targets for the development of a live-attenuated vaccine against R. equi infections. PMID:21901092

  2. Tick-Borne Encephalitis Virus Replication, Intracellular Trafficking, and Pathogenicity in Human Intestinal Caco-2 Cell Monolayers

    PubMed Central

    Möller, Lars; Schulzke, Joerg D.; Niedrig, Matthias; Bücker, Roland

    2014-01-01

    Tick-borne encephalitis virus (TBEV) is one of the most important vector-borne viruses in Europe and Asia. Its transmission mainly occurs by the bite of an infected tick. However, consuming milk products from infected livestock animals caused TBEV cases. To better understand TBEV transmission via the alimentary route, we studied viral infection of human intestinal epithelial cells. Caco-2 cells were used to investigate pathological effects of TBEV infection. TBEV-infected Caco-2 monolayers showed morphological changes including cytoskeleton rearrangements and cytoplasmic vacuolization. Ultrastructural analysis revealed dilatation of the rough endoplasmic reticulum and further enlargement to TBEV containing caverns. Caco-2 monolayers maintained an intact epithelial barrier with stable transepithelial electrical resistance (TER) during early stage of infection. Concomitantly, viruses were detected in the basolateral medium, implying a transcytosis pathway. When Caco-2 cells were pre-treated with inhibitors of cellular pathways of endocytosis TBEV cell entry was efficiently blocked, suggesting that actin filaments (Cytochalasin) and microtubules (Nocodazole) are important for PI3K-dependent (LY294002) virus endocytosis. Moreover, experimental fluid uptake assay showed increased intracellular accumulation of FITC-dextran containing vesicles. Immunofluorescence microscopy revealed co-localization of TBEV with early endosome antigen-1 (EEA1) as well as with sorting nexin-5 (SNX5), pointing to macropinocytosis as trafficking mechanism. In the late phase of infection, further evidence was found for translocation of virus via the paracellular pathway. Five days after infection TER was slightly decreased. Epithelial barrier integrity was impaired due to increased epithelial apoptosis, leading to passive viral translocation. These findings illuminate pathomechanisms in TBEV infection of human intestinal epithelial cells and viral transmission via the alimentary route. PMID:24820351

  3. Tick-borne encephalitis virus replication, intracellular trafficking, and pathogenicity in human intestinal Caco-2 cell monolayers.

    PubMed

    Yu, Chao; Achazi, Katharina; Möller, Lars; Schulzke, Joerg D; Niedrig, Matthias; Bücker, Roland

    2014-01-01

    Tick-borne encephalitis virus (TBEV) is one of the most important vector-borne viruses in Europe and Asia. Its transmission mainly occurs by the bite of an infected tick. However, consuming milk products from infected livestock animals caused TBEV cases. To better understand TBEV transmission via the alimentary route, we studied viral infection of human intestinal epithelial cells. Caco-2 cells were used to investigate pathological effects of TBEV infection. TBEV-infected Caco-2 monolayers showed morphological changes including cytoskeleton rearrangements and cytoplasmic vacuolization. Ultrastructural analysis revealed dilatation of the rough endoplasmic reticulum and further enlargement to TBEV containing caverns. Caco-2 monolayers maintained an intact epithelial barrier with stable transepithelial electrical resistance (TER) during early stage of infection. Concomitantly, viruses were detected in the basolateral medium, implying a transcytosis pathway. When Caco-2 cells were pre-treated with inhibitors of cellular pathways of endocytosis TBEV cell entry was efficiently blocked, suggesting that actin filaments (Cytochalasin) and microtubules (Nocodazole) are important for PI3K-dependent (LY294002) virus endocytosis. Moreover, experimental fluid uptake assay showed increased intracellular accumulation of FITC-dextran containing vesicles. Immunofluorescence microscopy revealed co-localization of TBEV with early endosome antigen-1 (EEA1) as well as with sorting nexin-5 (SNX5), pointing to macropinocytosis as trafficking mechanism. In the late phase of infection, further evidence was found for translocation of virus via the paracellular pathway. Five days after infection TER was slightly decreased. Epithelial barrier integrity was impaired due to increased epithelial apoptosis, leading to passive viral translocation. These findings illuminate pathomechanisms in TBEV infection of human intestinal epithelial cells and viral transmission via the alimentary route. PMID:24820351

  4. Codependent and independent effects of nitric oxide-mediated suppression of PhoPQ and Salmonella pathogenicity island 2 on intracellular Salmonella enterica serovar typhimurium survival.

    PubMed

    Bourret, Travis J; Song, Miryoung; Vázquez-Torres, Andrés

    2009-11-01

    Here we show that the Salmonella enterica serovar Typhimurium PhoQ sensor kinase lessens the cytotoxicity of reactive nitrogen species (RNS) generated by inducible nitric oxide synthase (iNOS) in the innate response of mononuclear phagocytic cells. This observation is consistent with the expression patterns of PhoP-activated genes during moderate nitrosative stress in the innate host response. In contrast, RNS synthesized during high-NO fluxes of gamma interferon (IFN-gamma)-activated macrophages repress PhoP-activated lpxO, pagP, and phoP gene transcription. Because PhoP-regulated Salmonella pathogenicity island 2 (SPI2) genes are also repressed by high-order RNS (39), we investigated whether the NO-mediated inhibition of PhoPQ underlies the repression of SPI2. Our studies indicate that a third of the expression of the SPI2 spiC gene recorded in nonactivated macrophages depends on PhoQ. Transcription of spiC is repressed in IFN-gamma-primed macrophages in an iNOS-dependent manner, irrespective of the phoQ status of the bacteria. Transcription of spiC is restored in IFN-gamma-treated, iNOS-deficient macrophages to levels sustained by a phoQ mutant in nonactivated phagocytes, suggesting that most NO-dependent repression of spiC is due to the inhibition of PhoPQ-independent targets. Comparison of the intracellular fitness of spiC, phoQ, and spiC phoQ mutants revealed that PhoPQ and SPI2 have codependent and independent effects on S. Typhimurium survival during innate nitrosative stress. However, the intracellular survival of most S. Typhimurium bacteria is conferred by the PhoPQ two-component regulator, and the SPI2 type III secretion system is repressed by high-order RNS of IFN-gamma-activated macrophages. PMID:19737903

  5. The IFN-?-inducible GTPase, Irga6, protects mice against Toxoplasma gondii but not against Plasmodium berghei and some other intracellular pathogens.

    PubMed

    Liesenfeld, Oliver; Parvanova, Iana; Zerrahn, Jens; Han, Seong-Ji; Heinrich, Frederik; Muñoz, Melba; Kaiser, Frank; Aebischer, Toni; Buch, Thorsten; Waisman, Ari; Reichmann, Gaby; Utermöhlen, Olaf; von Stebut, Esther; von Loewenich, Friederike D; Bogdan, Christian; Specht, Sabine; Saeftel, Michael; Hoerauf, Achim; Mota, Maria M; Könen-Waisman, Stephanie; Kaufmann, Stefan H E; Howard, Jonathan C

    2011-01-01

    Clearance of infection with intracellular pathogens in mice involves interferon-regulated GTPases of the IRG protein family. Experiments with mice genetically deficient in members of this family such as Irgm1(LRG-47), Irgm3(IGTP), and Irgd(IRG-47) has revealed a critical role in microbial clearance, especially for Toxoplasma gondii. The in vivo role of another member of this family, Irga6 (IIGP, IIGP1) has been studied in less detail. We investigated the susceptibility of two independently generated mouse strains deficient in Irga6 to in vivo infection with T. gondii, Mycobacterium tuberculosis, Leishmania mexicana, L. major, Listeria monocytogenes, Anaplasma phagocytophilum and Plasmodium berghei. Compared with wild-type mice, mice deficient in Irga6 showed increased susceptibility to oral and intraperitoneal infection with T. gondii but not to infection with the other organisms. Surprisingly, infection of Irga6-deficient mice with the related apicomplexan parasite, P. berghei, did not result in increased replication in the liver stage and no Irga6 (or any other IRG protein) was detected at the parasitophorous vacuole membrane in IFN-?-induced wild-type cells infected with P. berghei in vitro. Susceptibility to infection with T. gondii was associated with increased mortality and reduced time to death, increased numbers of inflammatory foci in the brains and elevated parasite loads in brains of infected Irga6-deficient mice. In vitro, Irga6-deficient macrophages and fibroblasts stimulated with IFN-? were defective in controlling parasite replication. Taken together, our results implicate Irga6 in the control of infection with T. gondii and further highlight the importance of the IRG system for resistance to this pathogen. PMID:21698150

  6. Depletion of autophagy-related genes ATG3 and ATG5 in Tenebrio molitor leads to decreased survivability against an intracellular pathogen, Listeria monocytogenes.

    PubMed

    Tindwa, Hamisi; Jo, Yong Hun; Patnaik, Bharat Bhusan; Noh, Mi Young; Kim, Dong Hyun; Kim, Iksoo; Han, Yeon Soo; Lee, Yong Seok; Lee, Bok Luel; Kim, Nam Jung

    2015-01-01

    Macroautophagy (autophagy) is an evolutionarily conserved catabolic process involved in physiological and developmental processes including cell survival, death, and innate immunity. Homologues of most of 36 originally discovered autophagy-related (ATG) genes in yeast have been characterized in higher eukaryotes including insects. In this study, the homologues of ATG3 (TmATG3) and ATG5 (TmATG5) were isolated from the coleopteran beetle, Tenebrio molitor by expressed sequence tag and RNAseq approaches. The cDNA of TmATG3 and TmATG5 comprise open-reading frame sizes of 963 and 792 bp encoding polypeptides of 320 and 263 amino acid residues, respectively. TmATG3 and TmATG5 mRNA are expressed in all developmental stages, and mainly in fat body and hemocytes of larvae. TmATG3 and TmATG5 showed an overall sequence identity of 58-95% to other insect Atg proteins. There exist clear one-to-one orthologs of TmATG3 and TmATG5 in Tribolium and that they clustered together in the gene tree. Depletion of TmATG3 and TmATG5 by RNA interference led to a significant reduction in survival ability of T. molitor larvae against an intracellular pathogen, Listeria monocytogenes. Six days post-Listeria challenge, the survival rate in the dsEGFP-injected (where EGFP is enhanced green fluorescent protein) control larvae was significantly higher (55%) compared to 4 and 3% for TmATG3 and TmATG5 double-stranded RNA injected larvae, respectively. These data suggested that TmATG3 and TmATG5 may play putative role in mediating autophagy-based clearance of Listeria in T. molitor model. PMID:25403020

  7. Genome Sequence of the Versatile Fish Pathogen Edwardsiella tarda Provides Insights into its Adaptation to Broad Host Ranges and Intracellular Niches

    PubMed Central

    Xiao, Jingfan; Wu, Haizhen; Wang, Xin; Lv, Yuanzhi; Xu, Lili; Zheng, Huajun; Wang, Shengyue; Zhao, Guoping; Liu, Qin; Zhang, Yuanxing

    2009-01-01

    Background Edwardsiella tarda is the etiologic agent of edwardsiellosis, a devastating fish disease prevailing in worldwide aquaculture industries. Here we describe the complete genome of E. tarda, EIB202, a highly virulent and multi-drug resistant isolate in China. Methodology/Principal Findings E. tarda EIB202 possesses a single chromosome of 3,760,463 base pairs containing 3,486 predicted protein coding sequences, 8 ribosomal rRNA operons, and 95 tRNA genes, and a 43,703 bp conjugative plasmid harboring multi-drug resistant determinants and encoding type IV A secretion system components. We identified a full spectrum of genetic properties related to its genome plasticity such as repeated sequences, insertion sequences, phage-like proteins, integrases, recombinases and genomic islands. In addition, analysis also indicated that a substantial proportion of the E. tarda genome might be devoted to the growth and survival under diverse conditions including intracellular niches, with a large number of aerobic or anaerobic respiration-associated proteins, signal transduction proteins as well as proteins involved in various stress adaptations. A pool of genes for secretion systems, pili formation, nonfimbrial adhesions, invasions and hemagglutinins, chondroitinases, hemolysins, iron scavenging systems as well as the incomplete flagellar biogenesis might feature its surface structures and pathogenesis in a fish body. Conclusion/Significance Genomic analysis of the bacterium offered insights into the phylogeny, metabolism, drug-resistance, stress adaptation, and virulence characteristics of this versatile pathogen, which constitutes an important first step in understanding the pathogenesis of E. tarda to facilitate construction of a practical effective vaccine used for combating fish edwardsiellosis. PMID:19865481

  8. Intracellular Parasite Invasion Strategies

    NASA Astrophysics Data System (ADS)

    Sibley, L. D.

    2004-04-01

    Intracellular parasites use various strategies to invade cells and to subvert cellular signaling pathways and, thus, to gain a foothold against host defenses. Efficient cell entry, ability to exploit intracellular niches, and persistence make these parasites treacherous pathogens. Most intracellular parasites gain entry via host-mediated processes, but apicomplexans use a system of adhesion-based motility called ``gliding'' to actively penetrate host cells. Actin polymerization-dependent motility facilitates parasite migration across cellular barriers, enables dissemination within tissues, and powers invasion of host cells. Efficient invasion has brought widespread success to this group, which includes Toxoplasma, Plasmodium, and Cryptosporidium.

  9. Biological and antibacterial activities of the natural herb Houttuynia cordata water extract against the intracellular bacterial pathogen salmonella within the RAW 264.7 macrophage.

    PubMed

    Kim, Gon Sup; Kim, Dong Hyeok; Lim, Jeong Ju; Lee, Jin Ju; Han, Dae Yong; Lee, Whi Min; Jung, Won Chul; Min, Won Gi; Won, Chung Gil; Rhee, Man Hee; Lee, Hu Jang; Kim, Suk

    2008-11-01

    Salmonellosis is a major bacterial zoonosis that causes a variety of disease syndromes, from self-limiting enteritis to fatal infection in animals and food-borne infection and typhoid fever in humans. Recently, the emergence of multidrug-resistant strains of Salmonella sp. has caused more serious problems in public health. The present study investigated the antibacterial effects of Houttuynia cordata water extract (HCWE) against murine salmonellosis. In RAW 264.7 cells, there was no detectable cytotoxic effect of HCWE at any concentration between 25 and 100 microg/ml after 8-h incubation. The antibacterial activity of HCWE was then examined in a Salmonella enterica serovar (Salmonella typhimurium), and was found to increase in a dose-dependent manner at concentrations from 25 to 100 microg/ml during 8-h incubation. HCWE also affected RAW 264.7 cells including morphologic change and bacterial uptake, but there was no significant difference in bacterial replication in RAW 264.7 cells. With HCWE alone, nitric oxide (NO) production by RAW 264.7 cells did not increase, but when RAW 264.7 cells were infected by S. typhimurium, with or without HCWE, NO production with HCWE was 2-fold higher than that without HCWE. Treatment with HCWE did not affect inducible NO synthase (iNOS) mRNA expression by RAW 264.7 cells, but when RAW 264.7 cells with HCWE were infected by S. typhimurium, iNOS mRNA expression was increased during 8-h incubation. Furthermore, HCWE showed virulence reduction effects in S. typhimurium-infected BALB/c mice. After a lethal dose of S. typhimurium, the mortality rate in the HCWE untreated group was 100% at 7 d, but the HCWE 25, 50, and 100 microg/ml groups survived until 11, 17, and 23 d, respectively. These data suggest that HCWE is stable and beneficial in the treatment of bacterial infection including intracellularly replicating pathogens and may solve antimicrobial misuse and overuse. PMID:18981565

  10. Reconceptualizing the chlamydial inclusion as a pathogen-specified parasitic organelle: an expanded role for Inc proteins

    PubMed Central

    Moore, Elizabeth R.; Ouellette, Scot P.

    2014-01-01

    Chlamydia is an obligate intracellular pathogen that develops in the host cell in a vacuole termed the chlamydial inclusion. The prevailing concept of the chlamydial inclusion is of a parasitophorous vacuole. Here, the inclusion is the recipient of one-way host-pathogen interactions thus draining nutrients from the cell and negatively impacting it. While Chlamydia orchestrates some aspects of cell function, recent data indicate host cells remain healthy up until, and even after, chlamydial egress. Thus, while Chlamydia relies on the host cell for necessary metabolites, the overall function of the host cell, during chlamydial growth and development, is not grossly disturbed. This is consistent with the obligate intracellular organism's interest to maintain viability of its host. To this end, Chlamydia expresses inclusion membrane proteins, Incs, which serve as molecular markers for the inclusion membrane. Incs also contribute to the physical structure of the inclusion membrane and facilitate host-pathogen interactions across it. Given the function of Incs and the dynamic interactions that occur at the inclusion membrane, we propose that the inclusion behaves similarly to an organelle-albeit one that benefits the pathogen. We present the hypothesis that the chlamydial inclusion acts as a pathogen-specified parasitic organelle. This representation integrates the inclusion within existing subcellular trafficking pathways to divert a subset of host-derived metabolites thus maintaining host cell homeostasis. We review the known interactions of the chlamydial inclusion with the host cell and discuss the role of Inc proteins in the context of this model and how this perspective can impact the study of these proteins. Lessons learnt from the chlamydial pathogen-specified parasitic organelle can be applied to other intracellular pathogens. This will increase our understanding of how intracellular pathogens engage the host cell to establish their unique developmental niches. PMID:25401095

  11. Disease Resistance in Atlantic Salmon (Salmo salar): Coinfection of the Intracellular Bacterial Pathogen Piscirickettsia salmonis and the Sea Louse Caligus rogercresseyi

    PubMed Central

    Lhorente, Jean Paul; Gallardo, José A.; Villanueva, Beatriz; Carabaño, María J.; Neira, Roberto

    2014-01-01

    Background Naturally occurring coinfections of pathogens have been reported in salmonids, but their consequences on disease resistance are unclear. We hypothesized that 1) coinfection of Caligus rogercresseyi reduces the resistance of Atlantic salmon to Piscirickettsia salmonis; and 2) coinfection resistance is a heritable trait that does not correlate with resistance to a single infection. Methodology In total, 1,634 pedigreed Atlantic salmon were exposed to a single infection (SI) of P. salmonis (primary pathogen) or coinfection with C. rogercresseyi (secondary pathogen). Low and high level of coinfection were evaluated (LC?=?44 copepodites per fish; HC?=?88 copepodites per fish). Survival and quantitative genetic analyses were performed to determine the resistance to the single infection and coinfections. Main Findings C. rogercresseyi significantly increased the mortality in fish infected with P. salmonis (SI mortality?=?251/545; LC mortality?=?544/544 and HC mortality?=?545/545). Heritability estimates for resistance to P. salmonis were similar and of medium magnitude in all treatments (h2SI?=?0.23±0.07; h2LC?=?0.17±0.08; h2HC?=?0.24±0.07). A large and significant genetic correlation with regard to resistance was observed between coinfection treatments (rg LC-HC?=?0.99±0.01) but not between the single and coinfection treatments (rg SI-LC?=??0.14±0.33; rg SI-HC?=?0.32±0.34). Conclusions/Significance C. rogercresseyi, as a secondary pathogen, reduces the resistance of Atlantic salmon to the pathogen P. salmonis. Resistance to coinfection of Piscirickettsia salmonis and Caligus rogercresseyi in Atlantic salmon is a heritable trait. The absence of a genetic correlation between resistance to a single infection and resistance to coinfection indicates that different genes control these processes. Coinfection of different pathogens and resistance to coinfection needs to be considered in future research on salmon farming, selective breeding and conservation. PMID:24736323

  12. Washing and Disinfecting Fish Gills: Preventing Contamination by Normal Surface Microflora of Cell Cultures Inoculated with Tissue for Isolating Intracellular Pathogens

    Microsoft Academic Search

    Agnar Kvellestad; Laila G. Aune; Birgit H. Dannevig

    2002-01-01

    Contamination of cell cultures by the normal microflora of water, to which fish gills are exposed, is a major obstacle to in vitro culture of the pathogenic and presumptively antibiotic-sensitive rickettsia- and chlamydia-like organisms infecting gill epithelial cells. Therefore, a protocol was developed for removal or inactivation of these potential contaminating organisms. Gills of Atlantic salmon Salmo salar were vigorously

  13. GRANDPARENTS' ENTITLEMENTS AND OBLIGATIONS

    PubMed Central

    Draper, Heather

    2013-01-01

    In this article, it is argued that grandparents' obligations originate from parental obligations (i.e from the relationship they have with their children, the parents of their grandchildren) and not from the role of grandparent per se, and any entitlements flow from the extent to which these obligations are met. The position defended is, therefore, that grandparents qua grandparents are not entitled to form or continue relationships with their grandchildren. A continuation of grandparent-grandchildren relationships may be in the interests of children, but the grandparental nature of the relationship is not decisive. What counts is the extent to which relationships children have with any adults who are not their parents are is significant to them. Sometimes, however, grandparents become parents or co-parents of their grandchildren. They then gain parental rights, and as such are as entitled, ceteris parius, as any parent to expect their relationship with the child to continue. The issue of grandparents' entitlements can come to the fore when parents separate, and grandparents are unhappy with the access they have to their grandchildren. Grandparents' obligations may become a particular issue when parents die, struggle, or fail to care for their children. This article focuses particularly on these kinds of circumstances. PMID:23718643

  14. Modals of Strong Obligation

    ERIC Educational Resources Information Center

    Matthews-Bresky, R. J. H.

    1977-01-01

    Discusses regularities and peculiarities in the use of the modal verbs of obligation "must,""need" and "should," also of the non-modals "have (got) to" and "need to." Agreements and differences in the use of the verbs are shown, with examples. Use of the various tense-forms is discussed. (IFS/WGA)

  15. Identification of pathogenic mechanisms of COCH mutations, abolished cochlin secretion and intracellular aggregate formation: genotype-phenotype correlations in DFNA9 deafness and vestibular disorder

    PubMed Central

    Cho, Hyun-Ju; Morton, Cynthia C.; Jung, Da Jung; Baek, Jeong-In; Choi, Soo-Young; Lee, Jaetae; Lee, Kyu-Yup; Kim, Un-Kyung

    2015-01-01

    Mutations in COCH cause autosomal dominant non-syndromic hearing loss with variable degrees of clinical onset and vestibular malfunction. We selected eight uncharacterized mutations and performed immunocytochemical and Western blot analyses to track cochlin through the secretory pathway. We then performed a comprehensive analysis of clinical information from DFNA9 patients with all 21 known COCH mutations in conjunction with cellular and molecular findings to identify genotype-phenotype correlations. Our studies revealed that five mutants were not secreted into the media: two vWFA domain mutants, which were not transported from the ER to Golgi complex and formed high-molecular-weight aggregates in cell lysates; and three LCCL domain mutants, which were detected as intracellular dimeric cochlins. Mutant cochlins that were not secreted and accumulated in cells result in earlier age of onset of hearing defects. In addition, individuals with LCCL domain mutations show accompanying vestibular dysfunction, whereas those with vWFA domain mutations exhibit predominantly hearing loss. This is the first report showing failure of mutant cochlin transport through the secretory pathway, abolishment of cochlin secretion, and formation and retention of dimers and large multimeric intracellular aggregates, and high correlation with earlier onset and progression of hearing loss in individuals with these DFNA9-causing mutations. PMID:25230692

  16. Nitric Oxide from IFN?-Primed Macrophages Modulates the Antimicrobial Activity of ?-Lactams against the Intracellular Pathogens Burkholderia pseudomallei and Nontyphoidal Salmonella

    PubMed Central

    Jones-Carson, Jessica; Zweifel, Adrienne E.; Tapscott, Timothy; Austin, Chad; Brown, Joseph M.; Jones, Kenneth L.; Voskuil, Martin I.; Vázquez-Torres, Andrés

    2014-01-01

    Our investigations show that nonlethal concentrations of nitric oxide (NO) abrogate the antibiotic activity of ?-lactam antibiotics against Burkholderia pseudomallei, Escherichia coli and nontyphoidal Salmonella enterica serovar Typhimurium. NO protects B. pseudomallei already exposed to ?-lactams, suggesting that this diatomic radical tolerizes bacteria against the antimicrobial activity of this important class of antibiotics. The concentrations of NO that elicit antibiotic tolerance repress consumption of oxygen (O2), while stimulating hydrogen peroxide (H2O2) synthesis. Transposon insertions in genes encoding cytochrome c oxidase-related functions and molybdenum assimilation confer B. pseudomallei a selective advantage against the antimicrobial activity of the ?-lactam antibiotic imipenem. Cumulatively, these data support a model by which NO induces antibiotic tolerance through the inhibition of the electron transport chain, rather than by potentiating antioxidant defenses as previously proposed. Accordingly, pharmacological inhibition of terminal oxidases and nitrate reductases tolerizes aerobic and anaerobic bacteria to ?-lactams. The degree of NO-induced ?-lactam antibiotic tolerance seems to be inversely proportional to the proton motive force (PMF), and thus the dissipation of ?H+ and ?? electrochemical gradients of the PMF prevents ?-lactam-mediated killing. According to this model, NO generated by IFN?-primed macrophages protects intracellular Salmonella against imipenem. On the other hand, sublethal concentrations of imipenem potentiate the killing of B. pseudomallei by NO generated enzymatically from IFN?-primed macrophages. Our investigations indicate that NO modulates the antimicrobial activity of ?-lactam antibiotics. PMID:25121731

  17. RNA sequencing of FACS-sorted immune cell populations from zebrafish infection models to identify cell specific responses to intracellular pathogens.

    PubMed

    Rougeot, Julien; Zakrzewska, Ania; Kanwal, Zakia; Jansen, Hans J; Spaink, Herman P; Meijer, Annemarie H

    2014-01-01

    The zebrafish (Danio rerio) is increasingly used as a model for studying infectious diseases. This nonmammalian vertebrate host, which is transparent at the early life stages, is especially attractive for live imaging of interactions between pathogens and host cells. A number of useful fluorescent reporter lines have recently been developed and significant advances in RNA sequencing technology have been made, which now make it possible to apply the zebrafish model for investigating changes in transcriptional activity of specific immune cell types during the course of an infection process.Here we describe how to sequence RNA extracted from fluorescently labeled macrophages obtained by cell-sorting of 5-day-old zebrafish larvae of the transgenic Tg(mpeg1:Gal4-VP16);Tg(UAS-E1b:Kaede) line. This technique showed reproducible results and allowed to detect specific expression of macrophage markers in the mpeg1 positive cell population, whereas no markers specific for neutrophils or lymphoid cells were detected. This protocol has been also successfully extended to other immune cell types as well as cells infected by Mycobacterium marinum. PMID:25172286

  18. Genomic organization, sequence characterization and expression analysis of Tenebrio molitor apolipophorin-III in response to an intracellular pathogen, Listeria monocytogenes.

    PubMed

    Noh, Ju Young; Patnaik, Bharat Bhusan; Tindwa, Hamisi; Seo, Gi Won; Kim, Dong Hyun; Patnaik, Hongray Howrelia; Jo, Yong Hun; Lee, Yong Seok; Lee, Bok Luel; Kim, Nam Jung; Han, Yeon Soo

    2014-01-25

    Apolipophorin III (apoLp-III) is a well-known hemolymph protein having a functional role in lipid transport and immune response of insects. We cloned full-length cDNA encoding putative apoLp-III from larvae of the coleopteran beetle, Tenebrio molitor (TmapoLp-III), by identification of clones corresponding to the partial sequence of TmapoLp-III, subsequently followed with full length sequencing by a clone-by-clone primer walking method. The complete cDNA consists of 890 nucleotides, including an ORF encoding 196 amino acid residues. Excluding a putative signal peptide of the first 20 amino acid residues, the 176-residue mature apoLp-III has a calculated molecular mass of 19,146Da. Genomic sequence analysis with respect to its cDNA showed that TmapoLp-III was organized into four exons interrupted by three introns. Several immune-related transcription factor binding sites were discovered in the putative 5'-flanking region. BLAST and phylogenetic analyses reveal that TmapoLp-III has high sequence identity (88%) with Tribolium castaneum apoLp-III but shares little sequence homologies (<26%) with other apoLp-IIIs. Homology modeling of Tm apoLp-III shows a bundle of five amphipathic alpha helices, including a short helix 3'. The 'helix-short helix-helix' motif was predicted to be implicated in lipid binding interactions, through reversible conformational changes and accommodating the hydrophobic residues to the exterior for stability. Highest level of TmapoLp-III mRNA was detected at late pupal stages, albeit it is expressed in the larval and adult stages at lower levels. The tissue specific expression of the transcripts showed significantly higher numbers in larval fat body and adult integument. In addition, TmapoLp-III mRNA was found to be highly upregulated in late stages of L. monocytogenes or E. coli challenge. These results indicate that TmapoLp-III may play an important role in innate immune responses against bacterial pathogens in T. molitor. PMID:24200961

  19. Intracellular Neutralization of Virus by Immunoglobulin A Antibodies

    NASA Astrophysics Data System (ADS)

    Mazanec, Mary B.; Kaetzel, Charlotte S.; Lamm, Michael E.; Fletcher, David; Nedrud, John G.

    1992-08-01

    IgA is thought to neutralize viruses at the epithelial surface of mucous membranes by preventing their attachment. Since IgA, a polymeric immunoglobulin, is transported through the lining of epithelial cells by the polymeric-immunoglobulin receptor and since viruses are obligate intracellular parasites, we hypothesized that IgA antibodies may also interfere with viral replication by binding to newly synthesized viral proteins within infected cells. Polarized monolayers of Madin-Darby canine kidney epithelial cells expressing the polymeric-immunoglobulin receptor were infected on the apical surface with Sendai virus. Anti-Sendai virus IgA monoclonal antibody delivered from the basolateral surface colocalized with viral protein within the cell, as documented by immunofluorescence. More importantly, anti-viral IgA reduced virus titers >1000-fold (P < 0.0001) in apical supernatants and >10-fold (P < 0.0001) in cell lysates from monolayers treated with anti-viral IgA compared with those treated with either anti-viral IgG or an irrelevant IgA monoclonal antibody. We believe that the differences in viral titers between cell layers treated with specific IgA, which enters the epithelial cell by binding to the polymeric-immunoglobulin receptor, and those treated with specific IgG, which does not enter the cells, or irrelevant IgA indicate that specific intracellular IgA antibodies can inhibit viral replication. Thus, in addition to the classical role of humoral antibodies in extracellular defense, IgA antibody may be able to neutralize microbial pathogens intracellularly, giving IgA a role in host defense that has traditionally been reserved for cell-mediated immunity.

  20. Chlamydia trachomatis-induced alterations in the host cell proteome are required for intracellular growth

    PubMed Central

    Olive, Andrew J.; Haff, Madeleine G.; Emanuele, Michael J.; Sack, Laura M.; Barker, Jeffrey R.; Elledge, Stephen J.; Starnbach, Michael N.

    2014-01-01

    Summary Intracellular pathogens directly alter host cells in order to replicate and survive. While infection-induced changes in host transcription can be readily assessed, post-transcriptional alterations are more difficult to catalog. We applied the global protein stability (GPS) platform, which assesses protein stability based on relative changes in an adjoining fluorescent tag, to identify changes in the host proteome following infection with the obligate intracellular bacteria Chlamydia trachomatis. Our results indicate that C. trachomatis profoundly remodels the host proteome independently of changes in transcription. Additionally, C. trachomatis replication depends on a subset of altered proteins, such as Pin1 and Men1, which regulate the host transcription factor AP-1 controlling host inflammation, stress, and cell survival. Furthermore, AP-1-dependent transcription is activated during infection, and required for efficient Chlamydia growth. In summary, this experimental approach revealed that C. trachomatis broadly alters host proteins and can be applied to examine host-pathogen interactions and develop host-based therapeutics. PMID:24439903

  1. No organization without obligations: How to formalize collective obligation?

    E-print Network

    Dignum, Frank

    of autonomous agents interact to achieve a certain task, for example to ful#12;l an obligation directed) has the responsibility to bring about a certain situation (to express group liability, e.g. liability

  2. Chlamydia pneumoniae harness host NLRP3 inflammasome-mediated caspase-1 activation for optimal intracellular growth in murine macrophages.

    PubMed

    Itoh, Ryota; Murakami, Issaku; Chou, Bin; Ishii, Kazunari; Soejima, Toshinori; Suzuki, Toshihiko; Hiromatsu, Kenji

    2014-09-26

    Chlamydia pneumoniae is an obligate intracellular pathogen that replicates within a vacuole and acquires host cell nutrients. We show that C. pneumoniae utilizes host innate immune signaling NLRP3/ASC/caspase-1 inflammasome for intracellular growth. Bone marrow-derived macrophages (BMMs) secreted mature interleukin-1? upon infection with C. pneumoniae depending on the NLRP3 inflammasome activation. Intracellular growth of C. pneumoniae was severely impaired in BMMs from Nlrp3(-/-), Asc(-/-), and Casp1(-/-) mice but not wild type or Nlrc4(-/-) mice. Furthermore defective NLRP3 inflammasome components led to accumulation of lipid droplets inside the infected BMMs, suggesting that uptake and/or utilization of lipids is disturbed in the absence of NLRP3 inflammasome activation. These results suggest C. pneumoniae has evolved to harness both host innate immune response and NLRP3 inflammasome activation, for the acquisition of essential nutrients necessary for intracellular growth. This unique property of C. pneumoniae may shed a new light on how C. pneumoniae increase the risk of atherosclerosis and metabolic syndrome. PMID:25193701

  3. The cell-penetrating peptide, Pep-1, has activity against intracellular chlamydial growth but not extracellular forms of Chlamydia trachomatis

    PubMed Central

    Park, Narae; Yamanaka, Kinrin; Tran, Dat; Chandrangsu, Pete; Akers, Johnny C.; de Leon, Jessica C.; Morrissette, Naomi S.; Selsted, Michael E.; Tan, Ming

    2009-01-01

    Objectives In the course of studies to identify novel treatment strategies against the pathogenic bacterium, Chlamydia, we tested the carrier peptide, Pep-1, for activity against an intracellular infection. Methods Using a cell culture model of Chlamydia trachomatis infection, the effect of Pep-1 was measured by incubating the peptide with extracellular chlamydiae prior to infection, or by adding Pep-1 to the medium at varying times after infection, and assaying for inhibition of inclusion formation. Results Pep-1 had a concentration-dependent effect on chlamydial growth with 100% inhibition of inclusion formation at 8 mg/L peptide. There was a window of susceptibility during the chlamydial developmental cycle with a maximal effect when treatment was begun within 12 h of infection. Pep-1 treatment caused a severe reduction in the production of infectious progeny even when started later, when the effect on inclusion formation was minimal. Furthermore, electron micrographs showed a paucity of progeny elementary bodies (EBs) in the inclusion. In contrast, pre-incubation of EBs with Pep-1 prior to infection did not affect inclusion formation. Taken together, these findings indicate that the antichlamydial effect was specific for the intracellular stage of chlamydial infection. By comparison, Pep-1 had no antimicrobial activity against Escherichia coli and Staphylococcus aureus or the obligate intracellular parasite, Toxoplasma gondii. Conclusions Pep-1 has antichlamydial activity by preventing intracellular chlamydial growth and replication but has no effect on extracellular chlamydiae. PMID:18957395

  4. 402 nature genetics volume 32 november 2002 Genome sequence of the endocellular obligate symbiont

    E-print Network

    Aksoy, Serap

    such intracellular microbe for nutritional provision- ing and fecundity. As a result of co-evolution with hosts over nutrition and fecundity, have been retained. Unexpectedly, this oblig- ate's genome bears hallmarks of both. Many arthropods with restricted diets, such as vertebrate blood, plant juice or wood, rely on symbiotic

  5. The Francisella Intracellular Life Cycle: Toward Molecular Mechanisms of Intracellular Survival and Proliferation

    PubMed Central

    Chong, Audrey; Celli, Jean

    2010-01-01

    The tularemia-causing bacterium Francisella tularensis is a facultative intracellular organism with a complex intracellular lifecycle that ensures its survival and proliferation in a variety of mammalian cell types, including professional phagocytes. Because this cycle is essential to Francisella pathogenesis and virulence, much research has focused on deciphering the mechanisms of its intracellular survival and replication and characterizing both bacterial and host determinants of the bacterium's intracellular cycle. Studies of various strains and host cell models have led to the consensual paradigm of Francisella as a cytosolic pathogen, but also to some controversy about its intracellular cycle. In this review, we will detail major findings that have advanced our knowledge of Francisella intracellular survival strategies and also attempt to reconcile discrepancies that exist in our molecular understanding of the Francisella–phagocyte interactions. PMID:21687806

  6. Being Pathogenic, Plastic, and Sexual while Living with a Nearly Minimal Bacterial Genome

    PubMed Central

    Sirand-Pugnet, Pascal; Lartigue, Carole; Marenda, Marc; Jacob, Daniel; Barré, Aurélien; Barbe, Valérie; Schenowitz, Chantal; Mangenot, Sophie; Couloux, Arnaud; Segurens, Beatrice; de Daruvar, Antoine; Blanchard, Alain; Citti, Christine

    2007-01-01

    Mycoplasmas are commonly described as the simplest self-replicating organisms, whose evolution was mainly characterized by genome downsizing with a proposed evolutionary scenario similar to that of obligate intracellular bacteria such as insect endosymbionts. Thus far, analysis of mycoplasma genomes indicates a low level of horizontal gene transfer (HGT) implying that DNA acquisition is strongly limited in these minimal bacteria. In this study, the genome of the ruminant pathogen Mycoplasma agalactiae was sequenced. Comparative genomic data and phylogenetic tree reconstruction revealed that ?18% of its small genome (877,438 bp) has undergone HGT with the phylogenetically distinct mycoides cluster, which is composed of significant ruminant pathogens. HGT involves genes often found as clusters, several of which encode lipoproteins that usually play an important role in mycoplasma–host interaction. A decayed form of a conjugative element also described in a member of the mycoides cluster was found in the M. agalactiae genome, suggesting that HGT may have occurred by mobilizing a related genetic element. The possibility of HGT events among other mycoplasmas was evaluated with the available sequenced genomes. Our data indicate marginal levels of HGT among Mycoplasma species except for those described above and, to a lesser extent, for those observed in between the two bird pathogens, M. gallisepticum and M. synoviae. This first description of large-scale HGT among mycoplasmas sharing the same ecological niche challenges the generally accepted evolutionary scenario in which gene loss is the main driving force of mycoplasma evolution. The latter clearly differs from that of other bacteria with small genomes, particularly obligate intracellular bacteria that are isolated within host cells. Consequently, mycoplasmas are not only able to subvert complex hosts but presumably have retained sexual competence, a trait that may prevent them from genome stasis and contribute to adaptation to new hosts. PMID:17511520

  7. The Olive Fly Endosymbiont, “Candidatus Erwinia dacicola,” Switches from an Intracellular Existence to an Extracellular Existence during Host Insect Development? †

    PubMed Central

    Estes, Anne M.; Hearn, David J.; Bronstein, Judith L.; Pierson, Elizabeth A.

    2009-01-01

    As polyphagous, holometabolous insects, tephritid fruit flies (Diptera: Tephritidae) provide a unique habitat for endosymbiotic bacteria, especially those microbes associated with the digestive system. Here we examine the endosymbiont of the olive fly [Bactrocera oleae (Rossi) (Diptera: Tephritidae)], a tephritid of great economic importance. “Candidatus Erwinia dacicola” was found in the digestive systems of all life stages of wild olive flies from the southwestern United States. PCR and microscopy demonstrated that “Ca. Erwinia dacicola” resided intracellularly in the gastric ceca of the larval midgut but extracellularly in the lumen of the foregut and ovipositor diverticulum of adult flies. “Ca. Erwinia dacicola” is one of the few nonpathogenic endosymbionts that transitions between intracellular and extracellular lifestyles during specific stages of the host's life cycle. Another unique feature of the olive fly endosymbiont is that unlike obligate endosymbionts of monophagous insects, “Ca. Erwinia dacicola” has a G+C nucleotide composition similar to those of closely related plant-pathogenic and free-living bacteria. These two characteristics of “Ca. Erwinia dacicola,” the ability to transition between intracellular and extracellular lifestyles and a G+C nucleotide composition similar to those of free-living relatives, may facilitate survival in a changing environment during the development of a polyphagous, holometabolous host. We propose that insect-bacterial symbioses should be classified based on the environment that the host provides to the endosymbiont (the endosymbiont environment). PMID:19767463

  8. 38 CFR 17.607 - Obligated service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...AFFAIRS MEDICAL Va Health Professional Scholarship Program § 17.607 Obligated service...for which the participant received a scholarship award under these regulations...obligation. A participant who received a scholarship as a full-time student must be...

  9. 38 CFR 17.607 - Obligated service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...AFFAIRS MEDICAL Va Health Professional Scholarship Program § 17.607 Obligated service...for which the participant received a scholarship award under these regulations...obligation. A participant who received a scholarship as a full-time student must be...

  10. 38 CFR 17.607 - Obligated service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...AFFAIRS MEDICAL Va Health Professional Scholarship Program § 17.607 Obligated service...for which the participant received a scholarship award under these regulations...obligation. A participant who received a scholarship as a full-time student must be...

  11. 45 CFR 2400.65 - Teaching obligation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...obligation. 2400.65 Section 2400.65 Public Welfare Regulations Relating to Public Welfare (Continued) JAMES MADISON MEMORIAL FELLOWSHIP FOUNDATION FELLOWSHIP PROGRAM REQUIREMENTS Special Conditions § 2400.65 Teaching obligation....

  12. 45 CFR 2400.65 - Teaching obligation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...obligation. 2400.65 Section 2400.65 Public Welfare Regulations Relating to Public Welfare (Continued) JAMES MADISON MEMORIAL FELLOWSHIP FOUNDATION FELLOWSHIP PROGRAM REQUIREMENTS Special Conditions § 2400.65 Teaching obligation....

  13. 45 CFR 2400.65 - Teaching obligation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...obligation. 2400.65 Section 2400.65 Public Welfare Regulations Relating to Public Welfare (Continued) JAMES MADISON MEMORIAL FELLOWSHIP FOUNDATION FELLOWSHIP PROGRAM REQUIREMENTS Special Conditions § 2400.65 Teaching obligation....

  14. 45 CFR 2400.65 - Teaching obligation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...obligation. 2400.65 Section 2400.65 Public Welfare Regulations Relating to Public Welfare (Continued) JAMES MADISON MEMORIAL FELLOWSHIP FOUNDATION FELLOWSHIP PROGRAM REQUIREMENTS Special Conditions § 2400.65 Teaching obligation....

  15. 45 CFR 2400.65 - Teaching obligation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...obligation. 2400.65 Section 2400.65 Public Welfare Regulations Relating to Public Welfare (Continued) JAMES MADISON MEMORIAL FELLOWSHIP FOUNDATION FELLOWSHIP PROGRAM REQUIREMENTS Special Conditions § 2400.65 Teaching obligation....

  16. 34 CFR 108.5 - Compliance obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION EQUAL ACCESS TO PUBLIC SCHOOL FACILITIES FOR THE BOY SCOUTS OF AMERICA AND OTHER DESIGNATED YOUTH GROUPS § 108.5 Compliance obligations. (a) The obligation of covered entities...

  17. 38 CFR 17.607 - Obligated service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...AFFAIRS MEDICAL Va Health Professional Scholarship Program § 17.607 Obligated service...for which the participant received a scholarship award under these regulations...obligation. A participant who received a scholarship as a full-time student must be...

  18. 34 CFR 108.5 - Compliance obligations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION EQUAL ACCESS TO PUBLIC SCHOOL FACILITIES FOR THE BOY SCOUTS OF AMERICA AND OTHER DESIGNATED YOUTH GROUPS § 108.5 Compliance obligations. (a) The obligation of covered entities...

  19. 34 CFR 108.5 - Compliance obligations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION EQUAL ACCESS TO PUBLIC SCHOOL FACILITIES FOR THE BOY SCOUTS OF AMERICA AND OTHER DESIGNATED YOUTH GROUPS § 108.5 Compliance obligations. (a) The obligation of covered entities...

  20. EVIDENCE FOR THE MACROPHAGE INDUCING GENE IN MYCOBACTERIUM INTRACELLULARE

    EPA Science Inventory

    Background: The Mycobacterium avium Complex (MAC) includes the species M. avium (MA), M. intracellulare (MI), and possibly others. Organisms belonging to the MAC are phylogenetically closely related, opportunistic pathogens. The macrophage inducing gene (mig) is the only well-des...

  1. Ehrlichia chaffeensis: a Prototypical Emerging Pathogen

    PubMed Central

    Paddock, Christopher D.; Childs, James E.

    2003-01-01

    Ehrlichia chaffeensis is an obligately intracellular, tick-transmitted bacterium that is maintained in nature in a cycle involving at least one and perhaps several vertebrate reservoir hosts. The moderate to severe disease caused by E. chaffeensis in humans, first identified in 1986 and reported for more than 1,000 patients through 2000, represents a prototypical “emerging infection.” Knowledge of the biology and natural history of E. chaffeensis, and of the epidemiology, clinical features, and laboratory diagnosis of the zoonotic disease it causes (commonly referred to as human monocytic ehrlichiosis [HME]) has expanded considerably in the period since its discovery. In this review, we summarize briefly the current understanding of the microbiology, pathogenesis, and clinical manifestations associated with this pathogen but focus primarily on discussing various ecological factors responsible for the recent recognition of this important and potentially life-threatening tick-borne disease. Perhaps the most pivotal element in the emergence of HME has been the staggering increases in white-tailed deer populations in the eastern United States during the 20th century. This animal serves as a keystone host for all life stages of the principal tick vector (Amblyomma americanum) and is perhaps the most important vertebrate reservoir host for E. chaffeensis. The contributions of other components, including expansion of susceptible human populations, growth and broadening geographical distributions of other potential reservoir species and A. americanum, and improvements in confirmatory diagnostic methods, are also explored. PMID:12525424

  2. The Obligate Human Pathogen, Neisseria gonorrhoeae, Is Polyploid

    Microsoft Academic Search

    Deborah M Tobiason; H. Steven Seifert

    2006-01-01

    We show using several methodologies that the Gram-negative, diplococcal-bacterium Neisseria gonorrhoeae has more than one complete genome copy per cell. Gene dosage measurements demonstrated that only a single replication initiation event per chromosome occurs per round of cell division, and that there is a single origin of replication. The region containing the origin does not encode any genes previously associated

  3. The essential role of the CopN protein in Chlamydia pneumoniae intracellular growth

    PubMed Central

    Huang, Jin; Lesser, Cammie F.; Lory, Stephen

    2008-01-01

    Bacterial virulence determinants can be identified, according to the molecular Koch’s postulates1, if inactivation of a gene associated with a suspected virulence trait results in a loss in pathogenicity. This approach is commonly used with genetically tractable organisms. However, the current lack of tools for targeted gene disruptions in obligate intracellular microbial pathogens seriously hampers the identification of their virulence factors. Here we demonstrate an approach to studying potential virulence factors of genetically intractable organisms, such as Chlamydia. Heterologous expression of Chlamydia pneumoniae CopN in yeast and mammalian cells resulted in a cell cycle arrest, presumably owing to alterations in the microtubule cytoskeleton. A screen of a small molecule library identified two compounds that alleviated CopN-induced growth inhibition in yeast. These compounds interfered with C. pneumoniae replication in mammalian cells, presumably by ‘knocking out’ CopN function, revealing an essential role of CopN in the support of C. pneumoniae growth during infection. This work demonstrates the role of a specific chlamydial protein in virulence. The chemical biology approach described here can be used to identify virulence factors, and the reverse chemical genetic strategy can result in the identification of lead compounds for the development of novel therapeutics. PMID:18830244

  4. Autophagy vitalizes the pathogenicity of pathogenic fungi.

    PubMed

    Liu, Xiao-Hong; Gao, Hui-Min; Xu, Fei; Lu, Jian-Ping; Devenish, Rodney J; Lin, Fu-Cheng

    2012-10-01

    Plant pathogenic fungi utilize a series of complex infection structures, in particular the appressorium, to gain entry to and colonize plant tissue. As a consequence of the accumulation of huge quantities of glycerol in the cell the appressorium generates immense intracellular turgor pressure allowing the penetration peg of the appressorium to penetrate the leaf cuticle. Autophagic processes are ubiquitous in eukaryotic cells and facilitate the bulk degradation of macromolecules and organelles. The study of autophagic processes has been extended from the model yeast Saccharomyces cerevisiae to pathogenic fungi such as the rice blast fungus Magnaporthe oryzae. Significantly, null mutants for the expression of M. oryzae autophagy gene homologs lose their pathogenicity for infection of host plants. Clarification of the functions and network of interactions between the proteins expressed by M. oryzae autophagy genes will lead to a better understanding of the role of autophagy in fungal pathogenesis and help in the development of new strategies for disease control. PMID:22935638

  5. Hijacking of Host Cellular Functions by an Intracellular Parasite, the Microsporidian Anncaliia algerae

    PubMed Central

    Panek, Johan; El Alaoui, Hicham; Mone, Anne; Urbach, Serge; Demettre, Edith; Texier, Catherine; Brun, Christine; Zanzoni, Andreas; Peyretaillade, Eric; Parisot, Nicolas; Lerat, Emmanuelle; Peyret, Pierre; Delbac, Frederic; Biron, David G.

    2014-01-01

    Intracellular pathogens including bacteria, viruses and protozoa hijack host cell functions to access nutrients and to bypass cellular defenses and immune responses. These strategies have been acquired through selective pressure and allowed pathogens to reach an appropriate cellular niche for their survival and growth. To get new insights on how parasites hijack host cellular functions, we developed a SILAC (Stable Isotope Labeling by Amino Acids in Cell culture) quantitative proteomics workflow. Our study focused on deciphering the cross-talk in a host-parasite association, involving human foreskin fibroblasts (HFF) and the microsporidia Anncaliia algerae, a fungus related parasite with an obligate intracellular lifestyle and a strong host dependency. The host-parasite cross-talk was analyzed at five post-infection times 1, 6, 12 and 24 hours post-infection (hpi) and 8 days post-infection (dpi). A significant up-regulation of four interferon-induced proteins with tetratricopeptide repeats IFIT1, IFIT2, IFIT3 and MX1 was observed at 8 dpi suggesting a type 1 interferon (IFN) host response. Quantitative alteration of host proteins involved in biological functions such as signaling (STAT1, Ras) and reduction of the translation activity (EIF3) confirmed a host type 1 IFN response. Interestingly, the SILAC approach also allowed the detection of 148 A. algerae proteins during the kinetics of infection. Among these proteins many are involved in parasite proliferation, and an over-representation of putative secreted effectors proteins was observed. Finally our survey also suggests that A. algerae could use a transposable element as a lure strategy to escape the host innate immune system. PMID:24967735

  6. Characterizing the Intracellular Distribution of Metabolites in Intact Chlamydia-Infected Cells by Raman and Two-Photon Microscopy

    PubMed Central

    Szaszák, Márta; Chang, Jiun Chiun; Leng, Weinan; Rupp, Jan; Ojcius, David M.; Kelley, Anne Myers

    2013-01-01

    Chlamydiaspecies are obligate intracellular pathogens that proliferate only within infected cells. Currently, there are no known techniques or systems that can probe the spatial distribution of metabolites of interest within intact Chlamydia-infected cells. Here we investigate the ability of Raman microscopy to probe the chemical composition of different compartments (nucleus, inclusion, and cytoplasm) of C. trachomatis-infected epithelial cells. The overall intensity of the Raman spectrum is greatest in the inclusions and lowest in the cytoplasm in fixed cells. Difference spectra generated by normalizing to the intensity of the strong 1004 cm?1 phenylalanine line show distinct differences among the three compartments. Most notably, the concentrations of adenine are greater in both the inclusions and the nucleus than in the cytoplasm, as seen by Raman microscopy. The source of the adenine was explored through a complementary approach, using two-photon microscopy imaging. Autofluorescence measurements of living, infected cells show that the adenine-containing molecules, NAD(P)H and FAD, are present mainly in the cytoplasm, suggesting that these molecules are not the source of the additional adenine signal in the nucleus and inclusions. Experiments of infected cells stained with a DNA-binding dye, Hoechst 33258, reveal that most of the DNA is present in the nucleus and the inclusions, suggesting that DNA/RNA is the main source of the additional Raman adenine signal in the nucleus and inclusions. Thus, Raman and two-photon microscopy are among the few non-invasive methods available to investigate cells infected with Chlamydia and, together, should also be useful for studying infection by other intracellular pathogens that survive within intracellular vacuoles. PMID:23541981

  7. M1 Protein-Dependent Intracellular Trafficking Promotes Persistence and Replication of Streptococcus pyogenes in Macrophages

    Microsoft Academic Search

    Erika Hertzén; Linda Johansson; Robert Wallin; Heike Schmidt; Mirko Kroll; Anders P. Rehn; Malak Kotb; Matthias Mörgelin; Anna Norrby-Teglund

    2010-01-01

    Streptococcus pyogenes is an important human pathogen that causes a variety of diseases including life-threatening invasive diseases, such as toxic shock and deep tissue infections. Although S. pyogenes are classically considered extracellular pathogens, a clinical significance of an intracellular source has been emphasized. In patients with deep tissue infections, an intracellular reservoir of S. pyogenes within macrophages was shown to

  8. Real-time molecular monitoring of chemical environment in obligate anaerobes during oxygen adaptive response

    PubMed Central

    Holman, Hoi-Ying N.; Wozei, Eleanor; Lin, Zhang; Comolli, Luis R.; Ball, David A.; Borglin, Sharon; Fields, Matthew W.; Hazen, Terry C.; Downing, Kenneth H.

    2009-01-01

    Determining the transient chemical properties of the intracellular environment can elucidate the paths through which a biological system adapts to changes in its environment, for example, the mechanisms that enable some obligate anaerobic bacteria to survive a sudden exposure to oxygen. Here we used high-resolution Fourier transform infrared (FTIR) spectromicroscopy to continuously follow cellular chemistry within living obligate anaerobes by monitoring hydrogen bond structures in their cellular water. We observed a sequence of well orchestrated molecular events that correspond to changes in cellular processes in those cells that survive, but only accumulation of radicals in those that do not. We thereby can interpret the adaptive response in terms of transient intracellular chemistry and link it to oxygen stress and survival. This ability to monitor chemical changes at the molecular level can yield important insights into a wide range of adaptive responses. PMID:19541631

  9. Real-Time Molecular Monitoring of Chemical Environment in ObligateAnaerobes during Oxygen Adaptive Response

    SciTech Connect

    Holman, Hoi-Ying N.; Wozei, Eleanor; Lin, Zhang; Comolli, Luis R.; Ball, David. A.; Borglin, Sharon; Fields, Matthew W.; Hazen, Terry C.; Downing, Kenneth H.

    2009-02-25

    Determining the transient chemical properties of the intracellular environment canelucidate the paths through which a biological system adapts to changes in its environment, for example, the mechanisms which enable some obligate anaerobic bacteria to survive a sudden exposure to oxygen. Here we used high-resolution Fourier Transform Infrared (FTIR) spectromicroscopy to continuously follow cellular chemistry within living obligate anaerobes by monitoring hydrogen bonding in their cellular water. We observed a sequence of wellorchestrated molecular events that correspond to changes in cellular processes in those cells that survive, but only accumulation of radicals in those that do not. We thereby can interpret the adaptive response in terms of transient intracellular chemistry and link it to oxygen stress and survival. This ability to monitor chemical changes at the molecular level can yield important insights into a wide range of adaptive responses.

  10. 38 CFR 17.607 - Obligated service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...AFFAIRS MEDICAL Va Health Professional Scholarship Program § 17.607 Obligated service...school year or part thereof for which a scholarship was awarded, but for no less than 2...obligation. A participant who receives a scholarship as a full-time student must be...

  11. Collectivizing rescue obligations in bioethics.

    PubMed

    Garrett, Jeremy R

    2015-02-01

    Bioethicists invoke a duty to rescue in a wide range of cases. Indeed, arguably, there exists an entire medical paradigm whereby vast numbers of medical encounters are treated as rescue cases. The intuitive power of the rescue paradigm is considerable, but much of this power stems from the problematic way that rescue cases are conceptualized-namely, as random, unanticipated, unavoidable, interpersonal events for which context is irrelevant and beneficence is the paramount value. In this article, I critique the basic assumptions of the rescue paradigm, reframe the ethical landscape in which rescue obligations are understood, and defend the necessity and value of a wider social and institutional view. Along the way, I move back and forth between ethical theory and a concrete case where the duty to rescue has been problematically applied: the purported duty to regularly return incidental findings and individual research results in genomic and genetic research. PMID:25674948

  12. Macrophage defense mechanisms against intracellular bacteria.

    PubMed

    Weiss, Günter; Schaible, Ulrich E

    2015-03-01

    Macrophages and neutrophils play a decisive role in host responses to intracellular bacteria including the agent of tuberculosis (TB), Mycobacterium tuberculosis as they represent the forefront of innate immune defense against bacterial invaders. At the same time, these phagocytes are also primary targets of intracellular bacteria to be abused as host cells. Their efficacy to contain and eliminate intracellular M. tuberculosis decides whether a patient initially becomes infected or not. However, when the infection becomes chronic or even latent (as in the case of TB) despite development of specific immune activation, phagocytes have also important effector functions. Macrophages have evolved a myriad of defense strategies to combat infection with intracellular bacteria such as M. tuberculosis. These include induction of toxic anti-microbial effectors such as nitric oxide and reactive oxygen intermediates, the stimulation of microbe intoxication mechanisms via acidification or metal accumulation in the phagolysosome, the restriction of the microbe's access to essential nutrients such as iron, fatty acids, or amino acids, the production of anti-microbial peptides and cytokines, along with induction of autophagy and efferocytosis to eliminate the pathogen. On the other hand, M. tuberculosis, as a prime example of a well-adapted facultative intracellular bacterium, has learned during evolution to counter-balance the host's immune defense strategies to secure survival or multiplication within this otherwise hostile environment. This review provides an overview of innate immune defense of macrophages directed against intracellular bacteria with a focus on M. tuberculosis. Gaining more insights and knowledge into this complex network of host-pathogen interaction will identify novel target sites of intervention to successfully clear infection at a time of rapidly emerging multi-resistance of M. tuberculosis against conventional antibiotics. PMID:25703560

  13. Macrophage defense mechanisms against intracellular bacteria

    PubMed Central

    Weiss, Günter; Schaible, Ulrich E

    2015-01-01

    Macrophages and neutrophils play a decisive role in host responses to intracellular bacteria including the agent of tuberculosis (TB), Mycobacterium tuberculosis as they represent the forefront of innate immune defense against bacterial invaders. At the same time, these phagocytes are also primary targets of intracellular bacteria to be abused as host cells. Their efficacy to contain and eliminate intracellular M. tuberculosis decides whether a patient initially becomes infected or not. However, when the infection becomes chronic or even latent (as in the case of TB) despite development of specific immune activation, phagocytes have also important effector functions. Macrophages have evolved a myriad of defense strategies to combat infection with intracellular bacteria such as M. tuberculosis. These include induction of toxic anti-microbial effectors such as nitric oxide and reactive oxygen intermediates, the stimulation of microbe intoxication mechanisms via acidification or metal accumulation in the phagolysosome, the restriction of the microbe's access to essential nutrients such as iron, fatty acids, or amino acids, the production of anti-microbial peptides and cytokines, along with induction of autophagy and efferocytosis to eliminate the pathogen. On the other hand, M. tuberculosis, as a prime example of a well-adapted facultative intracellular bacterium, has learned during evolution to counter-balance the host's immune defense strategies to secure survival or multiplication within this otherwise hostile environment. This review provides an overview of innate immune defense of macrophages directed against intracellular bacteria with a focus on M. tuberculosis. Gaining more insights and knowledge into this complex network of host-pathogen interaction will identify novel target sites of intervention to successfully clear infection at a time of rapidly emerging multi-resistance of M. tuberculosis against conventional antibiotics. PMID:25703560

  14. 24 CFR 891.755 - Obligations of the family.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Obligations of the family. 891.755 Section 891.755...Projects for the Nonelderly Handicapped Families and Individuals-Section 162 Assistance § 891.755 Obligations of the family. The obligations of the...

  15. 29 CFR 5.31 - Meeting wage determination obligations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    29 Labor 1 2014-07-01 2013-07-01 true Meeting wage determination obligations...determination may discharge his minimum wage obligations for the payment...subcontractor may discharge his minimum wage obligations for the...

  16. 46 CFR 298.30 - Nature and content of Obligations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...46 Shipping 8 2010-10-01 2010-10-01 false Nature and content of Obligations. 298.30 Section 298.30...ASSISTANCE OBLIGATION GUARANTEES Documentation § 298.30 Nature and content of Obligations. (a) Single page....

  17. 46 CFR 298.30 - Nature and content of Obligations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...46 Shipping 8 2012-10-01 2012-10-01 false Nature and content of Obligations. 298.30 Section 298.30...ASSISTANCE OBLIGATION GUARANTEES Documentation § 298.30 Nature and content of Obligations. (a) Single page....

  18. 46 CFR 298.30 - Nature and content of Obligations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...46 Shipping 8 2011-10-01 2011-10-01 false Nature and content of Obligations. 298.30 Section 298.30...ASSISTANCE OBLIGATION GUARANTEES Documentation § 298.30 Nature and content of Obligations. (a) Single page....

  19. 46 CFR 298.30 - Nature and content of Obligations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...46 Shipping 8 2014-10-01 2014-10-01 false Nature and content of Obligations. 298.30 Section 298.30...ASSISTANCE OBLIGATION GUARANTEES Documentation § 298.30 Nature and content of Obligations. (a) Single page....

  20. 46 CFR 298.30 - Nature and content of Obligations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...46 Shipping 8 2013-10-01 2013-10-01 false Nature and content of Obligations. 298.30 Section 298.30...ASSISTANCE OBLIGATION GUARANTEES Documentation § 298.30 Nature and content of Obligations. (a) Single page....

  1. 31 CFR 225.5 - Pledge of definitive Government obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Pledge of definitive Government obligations. 225.5 Section...ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS...225.5 Pledge of definitive Government obligations. (a) Type...

  2. 31 CFR 225.5 - Pledge of definitive Government obligations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... false Pledge of definitive Government obligations. 225.5 Section...ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS...225.5 Pledge of definitive Government obligations. (a) Type...

  3. 31 CFR 225.5 - Pledge of definitive Government obligations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... false Pledge of definitive Government obligations. 225.5 Section...ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS...225.5 Pledge of definitive Government obligations. (a) Type...

  4. 31 CFR 225.5 - Pledge of definitive Government obligations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... false Pledge of definitive Government obligations. 225.5 Section...ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS...225.5 Pledge of definitive Government obligations. (a) Type...

  5. 31 CFR 225.5 - Pledge of definitive Government obligations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Pledge of definitive Government obligations. 225.5 Section...ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS...225.5 Pledge of definitive Government obligations. (a) Type...

  6. 47 CFR 64.1300 - Payphone compensation obligation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Payphone compensation obligation. 64.1300... FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER... § 64.1300 Payphone compensation obligation. (a...by contract. (c) The compensation obligation set forth...

  7. Multi-locus tree and species tree approaches toward resolving a complex clade of downy mildews (Straminipila, Oomycota), including pathogens of beet and spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate species determination of plant pathogens is a prerequisite for their control and quarantine, and further for assessing their potential threat to crops. The family Peronosporaceae (Straminipila; Oomycota) consists of obligate biotrophic pathogens that cause downy mildew disease on angiosperm...

  8. doi:10.1155/2011/971968 Review Article Parasite Mitogen-Activated Protein Kinases as Drug Discovery Targets to Treat Human Protozoan Pathogens

    E-print Network

    License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Protozoan pathogens are a highly diverse group of unicellular organisms, several of which are significant human pathogens. One group of protozoan pathogens includes obligate intracellular parasites such as agents of malaria, leishmaniasis, babesiosis, and toxoplasmosis. The other group includes extracellular pathogens such as agents of giardiasis and amebiasis. An unfortunate unifying theme for most human protozoan pathogens is that highly effective treatments for them are generally lacking. We will review targeting protozoan mitogen-activated protein kinases (MAPKs) as a novel drug discovery approach towards developing better therapies, focusing on Plasmodia, Leishmania,andToxoplasma, about which the most is known. 1. General Properties of MAPKs Virtually all eukaryotic organisms possess MAPKs, signal transduction molecules that regulate cell functions such as tissue morphogenesis, cytoskeletal rearrangements, proliferation, differentiation, survival, immune responses, and adaptation/stress-response [1–3]. Encephalitozoon cuniculi is the only example to date of a eukaryote apparently lacking

  9. Intracellular Parasitism of Chlamydiae: Specific Infectivity of Chlamydiaphage Chp2 in Chlamydophila abortus?

    PubMed Central

    Skilton, R. J.; Cutcliffe, L. T.; Pickett, M. A.; Lambden, P. R.; Fane, B. A.; Clarke, I. N.

    2007-01-01

    The obligate intracellular nature of chlamydiae presents challenges to the characterization of its phages, which are potential tools for a genetic transfer system. An assay for phage infectivity is described, and the infectious properties of phage Chp2 were determined. PMID:17468245

  10. cPLA2 Regulates the Expression of Type I Interferons and Intracellular Immunity to Chlamydia trachomatis*

    PubMed Central

    Vignola, Mark J.; Kashatus, David F.; Taylor, Gregory A.; Counter, Christopher M.; Valdivia, Raphael H.

    2010-01-01

    Infection with the obligate bacterial intracellular pathogen Chlamydia trachomatis leads to the sustained activation of the small GTPase RAS and many of its downstream signaling components. In particular, the mitogen-activated protein kinase ERK and the calcium-dependent phospholipase cPLA2 are activated and are important for the onset of inflammatory responses. In this study we tested if activation of ERK and cPLA2 occurred as a result of RAS signaling during infection and determined the relative contribution of these signaling components to chlamydial replication and survival. We provide genetic and pharmacological evidence that during infection RAS, ERK, and, to a lesser extent, cPLA2 activation are uncoupled, suggesting that Chlamydia activates individual components of this signaling pathway in a non-canonical manner. In human cell lines, inhibition of ERK or cPLA2 signaling did not adversely impact C. trachomatis replication. In contrast, in murine cells, inhibition of ERK and cPLA2 played a significant protective role against C. trachomatis. We determined that cPLA2-deficient murine cells are permissive for C. trachomatis replication because of their impaired expression of ? interferon and the induction of immunity-related GTPases (IRG) important for the containment of intracellular pathogens. Furthermore, the MAPK p38 was primarily responsible for cPLA2 activation in Chlamydia-infected cells and IRG expression. Overall, these findings define a previously unrecognized role for cPLA2 in the induction of cell autonomous cellular immunity to Chlamydia and highlight the many non-canonical signaling pathways engaged during infection. PMID:20452986

  11. Intracellular functions of galectins

    Microsoft Academic Search

    Fu-Tong Liu; Ronald J Patterson; John L Wang

    2002-01-01

    Many galectin family members are detected primarily intracellularly in most of the systems studied, although certain members can be found both inside and outside of cells. Specific functions that are consistent with their intracellular localization have now been documented for some of the galectins. Galectin-1 and -3 have been identified as redundant pre-mRNA splicing factors. Galectin-3, -7, and -12 have

  12. 7 CFR 989.37 - Obligation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...MARKETING SERVICE (Marketing Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE RAISINS PRODUCED FROM GRAPES GROWN IN CALIFORNIA Order Regulating Handling Raisin Administrative Committee § 989.37 Obligation....

  13. Naval Engineering A National Naval Obligation

    E-print Network

    Chryssostomidis, Chryssostomos

    2000-05-16

    As part of its national obligations, ONR must ensure US world leadership in those unique technology areas that insure naval superiority. ONR accomplishes this mission through research, recruitment and education, maintaining ...

  14. 19 CFR 10.849 - Importer obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Haitian Hemispheric Opportunity through Partnership Encouragement Act of 2006 § 10.849 Importer obligations. (a)...

  15. 19 CFR 10.849 - Importer obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Haitian Hemispheric Opportunity through Partnership Encouragement Act of 2006 § 10.849 Importer obligations. (a)...

  16. 19 CFR 10.849 - Importer obligations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Haitian Hemispheric Opportunity through Partnership Encouragement Act of 2006 § 10.849 Importer obligations. (a)...

  17. 19 CFR 10.849 - Importer obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Haitian Hemispheric Opportunity through Partnership Encouragement Act of 2006 § 10.849 Importer obligations. (a)...

  18. 19 CFR 10.849 - Importer obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Haitian Hemispheric Opportunity through Partnership Encouragement Act of 2006 § 10.849 Importer obligations. (a)...

  19. 19 CFR 10.805 - Importer obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Bahrain Free Trade Agreement Import Requirements § 10.805 Importer obligations. (a) General. An importer who...

  20. 38 CFR 17.632 - Obligated service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...17.632 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS MEDICAL Visual Impairment and Orientation and Mobility Professional Scholarship Program § 17.632 Obligated service. (a) General provision....

  1. 19 CFR 10.585 - Importer obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Dominican Republic-Central America-United States Free Trade Agreement Import Requirements § 10.585 Importer obligations. (a) General. An...

  2. 19 CFR 10.1005 - Importer obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Korea Free Trade Agreement Import Requirements § 10.1005 Importer obligations. (a) General. An importer who...

  3. 19 CFR 10.1005 - Importer obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Korea Free Trade Agreement Import Requirements § 10.1005 Importer obligations. (a) General. An importer who...

  4. 5 CFR 352.908 - Agency obligation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS REEMPLOYMENT RIGHTS Reemployment Rights After Service With the Panama Canal Commission § 352.908 Agency obligation. (a) Time limits. An employee is to be reemployed by the...

  5. 5 CFR 352.908 - Agency obligation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS REEMPLOYMENT RIGHTS Reemployment Rights After Service With the Panama Canal Commission § 352.908 Agency obligation. (a) Time limits. An employee is to be reemployed by the...

  6. 5 CFR 352.908 - Agency obligation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS REEMPLOYMENT RIGHTS Reemployment Rights After Service With the Panama Canal Commission § 352.908 Agency obligation. (a) Time limits. An employee is to be reemployed by the...

  7. 5 CFR 352.908 - Agency obligation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS REEMPLOYMENT RIGHTS Reemployment Rights After Service With the Panama Canal Commission § 352.908 Agency obligation. (a) Time limits. An employee is to be reemployed by the...

  8. 5 CFR 352.908 - Agency obligation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS REEMPLOYMENT RIGHTS Reemployment Rights After Service With the Panama Canal Commission § 352.908 Agency obligation. (a) Time limits. An employee is to be reemployed by the...

  9. 19 CFR 10.512 - Importer obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Singapore Free Trade Agreement Import Requirements § 10.512 Importer obligations. (a) General. An...

  10. 46 CFR Sec. 11 - Guarantee obligations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 11 Guarantee obligations. (a) Under the provisions of Article 10 of the NSA-LUMPSUMREP Contract the Contractor's guarantee liability...

  11. 46 CFR Sec. 11 - Guarantee obligations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 11 Guarantee obligations. (a) Under the provisions of Article 10 of the NSA-LUMPSUMREP Contract the Contractor's guarantee liability...

  12. 46 CFR Sec. 11 - Guarantee obligations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 11 Guarantee obligations. (a) Under the provisions of Article 10 of the NSA-LUMPSUMREP Contract the Contractor's guarantee liability...

  13. 46 CFR Sec. 11 - Guarantee obligations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 11 Guarantee obligations. (a) Under the provisions of Article 10 of the NSA-LUMPSUMREP Contract the Contractor's guarantee liability...

  14. 46 CFR Sec. 11 - Guarantee obligations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 11 Guarantee obligations. (a) Under the provisions of Article 10 of the NSA-LUMPSUMREP Contract the Contractor's guarantee liability...

  15. 19 CFR 10.765 - Importer obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Morocco Free Trade Agreement Import Requirements § 10.765 Importer obligations. (a) General . An importer who...

  16. 19 CFR 10.412 - Importer obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

  17. 19 CFR 10.412 - Importer obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

  18. 19 CFR 10.412 - Importer obligations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

  19. 19 CFR 10.412 - Importer obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

  20. 19 CFR 10.412 - Importer obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

  1. Filial Obligations in Post-Divorce Stepfamilies

    Microsoft Academic Search

    Marilyn Coleman; Lawrence H. Ganong; Jason D. Hans; Elizabeth A. Sharp; Tanja C. Rothrauff

    2005-01-01

    The purpose of this study was to assess adult children's obligations to assist older divorced parents and stepparents. Attitudes of 1,009 randomly selected participants were elicited using a vignette that portrayed a situation adult (step)children experience in post-divorce families. Findings suggest that, (a) adult children are obligated to help their divorced parents, (b) kinship is not a sufficient reason for

  2. Authentic Springs of Action and Obligation

    Microsoft Academic Search

    Ishtiyaque Haji

    2008-01-01

    What is the connection between action that is caused by inauthentic antecedent springs of action, such as surreptitiously\\u000a engineered-in desires and beliefs, and moral obligation? If, for example, an agent performs an action that derives from such\\u000a antecedent springs can it be that the agent is not obligated to perform this action owing to the inauthenticity of its causal antecedents?

  3. TRENDS IN CODON AND AMINO ACID USAGE IN HUMAN PATHOGEN TROPHERYMA WHIPPLEI, THE ONLY KNOWN

    E-print Network

    Wong, Limsoon

    ACTINOBACTERIA WITH REDUCED GENOME SABYASACHI DAS, SANDIP PAUL and CHITRA DUTTA Bioinformatics Centre, Indian multisystemic bacterial infection caused by an intracellular pathogenic actinobacteria Tropheryma whipplei.1

  4. Chloride Channels of Intracellular Membranes

    PubMed Central

    Edwards, John C.; Kahl, Christina R.

    2010-01-01

    Proteins implicated as intracellular chloride channels include the intracellular ClC proteins, the bestrophins, the cystic fibrosis transmembrane conductance regulator, the CLICs, and the recently described Golgi pH regulator. This paper examines current hypotheses regarding roles of intracellular chloride channels and reviews the evidence supporting a role in intracellular chloride transport for each of these proteins. PMID:20100480

  5. Microsporidia Are Natural Intracellular Parasites of the Nematode Caenorhabditis elegans

    PubMed Central

    Troemel, Emily R; Félix, Marie-Anne; Whiteman, Noah K; Barrière, Antoine; Ausubel, Frederick M

    2008-01-01

    For decades the soil nematode Caenorhabditis elegans has been an important model system for biology, but little is known about its natural ecology. Recently, C. elegans has become the focus of studies of innate immunity and several pathogens have been shown to cause lethal intestinal infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells, and no pathogen has been isolated from wild-caught C. elegans. Here we describe an intracellular pathogen isolated from wild-caught C. elegans that we show is a new species of microsporidia. Microsporidia comprise a large class of eukaryotic intracellular parasites that are medically and agriculturally important, but poorly understood. We show that microsporidian infection of the C. elegans intestine proceeds through distinct stages and is transmitted horizontally. Disruption of a conserved cytoskeletal structure in the intestine called the terminal web correlates with the release of microsporidian spores from infected cells, and appears to be part of a novel mechanism by which intracellular pathogens exit from infected cells. Unlike in bacterial intestinal infections, the p38 MAPK and insulin/insulin-like growth factor (IGF) signaling pathways do not appear to play substantial roles in resistance to microsporidian infection in C. elegans. We found microsporidia in multiple wild-caught isolates of Caenorhabditis nematodes from diverse geographic locations. These results indicate that microsporidia are common parasites of C. elegans in the wild. In addition, the interaction between C. elegans and its natural microsporidian parasites provides a system in which to dissect intracellular intestinal infection in vivo and insight into the diversity of pathogenic mechanisms used by intracellular microbes. PMID:19071962

  6. Microsporidia are natural intracellular parasites of the nematode Caenorhabditis elegans.

    PubMed

    Troemel, Emily R; Félix, Marie-Anne; Whiteman, Noah K; Barrière, Antoine; Ausubel, Frederick M

    2008-12-01

    For decades the soil nematode Caenorhabditis elegans has been an important model system for biology, but little is known about its natural ecology. Recently, C. elegans has become the focus of studies of innate immunity and several pathogens have been shown to cause lethal intestinal infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells, and no pathogen has been isolated from wild-caught C. elegans. Here we describe an intracellular pathogen isolated from wild-caught C. elegans that we show is a new species of microsporidia. Microsporidia comprise a large class of eukaryotic intracellular parasites that are medically and agriculturally important, but poorly understood. We show that microsporidian infection of the C. elegans intestine proceeds through distinct stages and is transmitted horizontally. Disruption of a conserved cytoskeletal structure in the intestine called the terminal web correlates with the release of microsporidian spores from infected cells, and appears to be part of a novel mechanism by which intracellular pathogens exit from infected cells. Unlike in bacterial intestinal infections, the p38 MAPK and insulin/insulin-like growth factor (IGF) signaling pathways do not appear to play substantial roles in resistance to microsporidian infection in C. elegans. We found microsporidia in multiple wild-caught isolates of Caenorhabditis nematodes from diverse geographic locations. These results indicate that microsporidia are common parasites of C. elegans in the wild. In addition, the interaction between C. elegans and its natural microsporidian parasites provides a system in which to dissect intracellular intestinal infection in vivo and insight into the diversity of pathogenic mechanisms used by intracellular microbes. PMID:19071962

  7. Intracellular biology and virulence determinants of Francisella tularensis revealed by transcriptional profiling inside macrophages

    PubMed Central

    Wehrly, Tara D.; Chong, Audrey; Virtaneva, Kimmo; Sturdevant, Dan E.; Child, Robert; Edwards, Jessica A.; Brouwer, Dedeke; Nair, Vinod; Fischer, Elizabeth R.; Wicke, Luke; Curda, Alissa J.; Kupko, John J.; Martens, Craig; Crane, Deborah D.; Bosio, Catharine M.; Porcella, Stephen F.; Celli, Jean

    2009-01-01

    Summary The highly infectious bacterium Francisella tularensis is a facultative intracellular pathogen, whose virulence requires proliferation inside host cells, including macrophages. Here we have performed a global transcriptional profiling of the highly virulent F. tularensis subsp. tularensis Schu S4 strain during its intracellular cycle within primary murine macrophages, to characterize its intracellular biology and identify pathogenic determinants based on their intracellular expression profiles. Phagocytosed bacteria rapidly responded to their intracellular environment and subsequently altered their transcriptional profile. Differential gene expression profiles were revealed that correlated with specific intracellular locale of the bacteria. Upregulation of general and oxidative stress response genes was a hallmark of the early phagosomal and late endosomal stages, while induction of transport and metabolic genes characterized the cytosolic replication stage. Expression of the Francisella Pathogenicity Island (FPI) genes, which are required for intracellular proliferation, increased during the intracellular cycle. Similarly, 27 chromosomal loci encoding putative hypothetical, secreted, outer membrane proteins or transcriptional regulators were identified as upregulated. Among these, deletion of FTT0383, FTT0369c or FTT1676 abolished the ability of Schu S4 to survive or proliferate intracellularly and cause lethality in mice, therefore identifying novel determinants of Francisella virulence from their intracellular expression profile. PMID:19388904

  8. Mechanisms of Francisella tularensis Intracellular Pathogenesis

    PubMed Central

    Celli, Jean

    2013-01-01

    Francisella tularensis is a zoonotic intracellular pathogen and the causative agent of the debilitating febrile illness tularemia. Although natural infections by F. tularensis are sporadic and generally localized, the low infectious dose, with the ability to be transmitted to humans via multiple routes and the potential to cause life-threatening infections, has led to concerns that this bacterium could be used as an agent of bioterror and released intentionally into the environment. Recent studies of F. tularensis and other closely related Francisella species have greatly increased our understanding of mechanisms used by this organism to infect and cause disease within the host. Here, we review the intracellular life cycle of Francisella and highlight key genetic determinants and/or pathways that contribute to the survival and proliferation of this bacterium within host cells. PMID:23545572

  9. Abnormalities in the handling of intracellular bacteria in Crohn's disease.

    PubMed

    Lapaquette, Pierre; Darfeuille-Michaud, Arlette

    2010-09-01

    Ileal lesions in Crohn's disease (CD) patients are colonized by pathogenic adherent-invasive Escherichia coli (AIEC) able to invade and to replicate within intestinal epithelial cells. Recent advances have highlighted the importance of the innate immune system and the critical relationship between the gut flora and the intestinal mucosa. Several combinations of genetic predisposing factors to CD have been described, with the most significant replicable associations including genes for intracellular receptor of bacterial cell walls (NOD2/CARD15), and for bacterial clearance and antigen processing through autophagy (ATG16L1 and IRGM). We recently reported that in IRGM and ATG16L1 deficient cells, intracellular AIEC LF82 bacteria have enhanced replication and that autophagy deficiency surprisingly did not interfere with the ability of intracellular bacteria to survive and/or replicate for any other E. coli strains tested, including nonpathogenic, environmental, commensal, or pathogenic strains involved in gastroenteritis. As autophagy is an innate defense mechanism acting as a cell-autonomous system for elimination of intracellular pathogens, these findings lead weight to the notion that intracellular bacteria including AIEC might play a role in CD pathogenesis. PMID:20616747

  10. Pathogen–host reorganization during Chlamydia invasion revealed by cryo-electron tomography

    PubMed Central

    Nans, Andrea; Saibil, Helen R; Hayward, Richard D

    2014-01-01

    Invasion of host cells is a key early event during bacterial infection, but the underlying pathogen–host interactions are yet to be fully visualized in three-dimensional detail. We have captured snapshots of the early stages of bacterial-mediated endocytosis in situ by exploiting the small size of chlamydial elementary bodies (EBs) for whole-cell cryo-electron tomography. Chlamydiae are obligate intracellular bacteria that infect eukaryotic cells and cause sexually transmitted infections and trachoma, the leading cause of preventable blindness. We demonstrate that Chlamydia trachomatis?LGV2 EBs are intrinsically polarized. One pole is characterized by a tubular inner membrane invagination, while the other exhibits asymmetric periplasmic expansion to accommodate an array of type III secretion systems (T3SSs). Strikingly, EBs orient with their T3SS-containing pole facing target cells, enabling the T3SSs to directly contact the cellular plasma membrane. This contact induces enveloping macropinosomes, actin-rich filopodia and phagocytic cups to zipper tightly around the internalizing bacteria. Once encapsulated into tight early vacuoles, EB polarity and the T3SSs are lost. Our findings reveal previously undescribed structural transitions in both pathogen and host during the initial steps of chlamydial invasion. PMID:24809274

  11. Unveiling the Intracellular Survival Gene Kit of Trypanosomatid Parasites

    PubMed Central

    Bartholomeu, Daniella Castanheira; de Paiva, Rita Marcia Cardoso; Mendes, Tiago A. O.; DaRocha, Wanderson D.; Teixeira, Santuza M. R.

    2014-01-01

    Trypanosomatids are unicellular protozoans of medical and economical relevance since they are the etiologic agents of infectious diseases in humans as well as livestock. Whereas Trypanosoma cruzi and different species of Leishmania are obligate intracellular parasites, Trypanosoma brucei and other trypanosomatids develop extracellularly throughout their entire life cycle. After their genomes have been sequenced, various comparative genomic studies aimed at identifying sequences involved with host cell invasion and intracellular survival have been described. However, for only a handful of genes, most of them present exclusively in the T. cruzi or Leishmania genomes, has there been any experimental evidence associating them with intracellular parasitism. With the increasing number of published complete genome sequences of members of the trypanosomatid family, including not only different Trypanosoma and Leishmania strains and subspecies but also trypanosomatids that do not infect humans or other mammals, we may now be able to contemplate a slightly better picture regarding the specific set of parasite factors that defines each organism's mode of living and the associated disease phenotypes. Here, we review the studies concerning T. cruzi and Leishmania genes that have been implicated with cell invasion and intracellular parasitism and also summarize the wealth of new information regarding the mode of living of intracellular parasites that is resulting from comparative genome studies that are based on increasingly larger trypanosomatid genome datasets. PMID:25474314

  12. Quantification and characterization of mucosa-associated and intracellular Escherichia coli in inflamatory bowel disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background and aims: Mucosa-associated E. coli are abundant in Crohn’s disease (CD) but whether these bacteria gain intracellular access within the mucosa is less certain. If E. coli does gain intracellular access in CD, the contribution of bacterial pathogenicity as opposed to a defect in host inna...

  13. Novel bioactive hydrophobic gentamicin carriers for the treatment of intracellular bacterial infections

    Microsoft Academic Search

    Edurne Imbuluzqueta; Elisa Elizondo; Carlos Gamazo; Evelyn Moreno-Calvo; Jaume Veciana; Nora Ventosa; María J. Blanco-Prieto

    2011-01-01

    Gentamicin (GEN) is an aminoglycoside antibiotic with a potent antibacterial activity against a wide variety of bacteria. However, its poor cellular penetration limits its use in the treatment of infections caused by intracellular pathogens. One potential strategy to overcome this problem is the use of particulate carriers that can target the intracellular sites of infection. In this study GEN was

  14. 40 CFR 1043.30 - General obligations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...EMISSIONS FROM MARINE ENGINES AND VESSELS SUBJECT TO THE MARPOL PROTOCOL § 1043.30 General obligations. (a) 33 U.S...prohibits any person from violating any provisions of the MARPOL Protocol, whether or not they are a manufacturer, owner or...

  15. 40 CFR 1043.30 - General obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...EMISSIONS FROM MARINE ENGINES AND VESSELS SUBJECT TO THE MARPOL PROTOCOL § 1043.30 General obligations. (a) 33 U.S...prohibits any person from violating any provisions of the MARPOL Protocol, whether or not they are a manufacturer, owner or...

  16. The author’s opportunity and obligation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peer review is a critical component of the scientific method and therefore should be an obligation for everyone who desires to publish their research results in refereed journals. This editorial is written to address a specific problem being encountered by editors of Soil & Tillage Research, but the...

  17. The Intracellular Bacteria Chlamydia Hijack Peroxisomes and Utilize Their Enzymatic Capacity to Produce Bacteria-Specific Phospholipids

    PubMed Central

    Boncompain, Gaelle; Müller, Constanze; Meas-Yedid, Vannary; Schmitt-Kopplin, Philippe; Lazarow, Paul B.; Subtil, Agathe

    2014-01-01

    Chlamydia trachomatis is an obligate intracellular pathogen responsible for loss of eyesight through trachoma and for millions of cases annually of sexually transmitted diseases. The bacteria develop within a membrane-bounded inclusion. They lack enzymes for several biosynthetic pathways, including those to make some phospholipids, and exploit their host to compensate. Three-dimensional fluorescence microscopy demonstrates that small organelles of the host, peroxisomes, are translocated into the Chlamydia inclusion and are found adjacent to the bacteria. In cells deficient for peroxisome biogenesis the bacteria are able to multiply and give rise to infectious progeny, demonstrating that peroxisomes are not essential for bacterial development in vitro. Mass spectrometry-based lipidomics reveal the presence in C. trachomatis of plasmalogens, ether phospholipids whose synthesis begins in peroxisomes and have never been described in aerobic bacteria before. Some of the bacterial plasmalogens are novel structures containing bacteria-specific odd-chain fatty acids; they are not made in uninfected cells nor in peroxisome-deficient cells. Their biosynthesis is thus accomplished by the metabolic collaboration of peroxisomes and bacteria. PMID:24465954

  18. 12 CFR 966.2 - Issuance of consolidated obligations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...Section 966.2 Banks and Banking FEDERAL HOUSING FINANCE BOARD FEDERAL HOME LOAN BANK LIABILITIES CONSOLIDATED... (a) Consolidated obligations issued by the Finance Board. The Finance Board may issue consolidated obligations...

  19. 18 CFR 367.22 - Accounting for asset retirement obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Accounting for asset retirement obligations...General Instructions § 367.22 Accounting for asset retirement obligations...retirement cost must be stated at the fair value of the asset retirement...

  20. 18 CFR 367.22 - Accounting for asset retirement obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Accounting for asset retirement obligations...General Instructions § 367.22 Accounting for asset retirement obligations...retirement cost must be stated at the fair value of the asset retirement...

  1. 18 CFR 367.22 - Accounting for asset retirement obligations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Accounting for asset retirement obligations...General Instructions § 367.22 Accounting for asset retirement obligations...retirement cost must be stated at the fair value of the asset retirement...

  2. 18 CFR 367.22 - Accounting for asset retirement obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Accounting for asset retirement obligations...General Instructions § 367.22 Accounting for asset retirement obligations...retirement cost must be stated at the fair value of the asset retirement...

  3. 22 CFR 221.15 - Fiscal Agent obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...false Fiscal Agent obligations. 221.15 Section 221.15 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS AND CONDITIONS The Guarantee § 221.15 Fiscal Agent obligations. Failure of the...

  4. 22 CFR 221.15 - Fiscal Agent obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...false Fiscal Agent obligations. 221.15 Section 221.15 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS AND CONDITIONS The Guarantee § 221.15 Fiscal Agent obligations. Failure of the...

  5. 22 CFR 221.15 - Fiscal Agent obligations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...false Fiscal Agent obligations. 221.15 Section 221.15 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS AND CONDITIONS The Guarantee § 221.15 Fiscal Agent obligations. Failure of the...

  6. 22 CFR 221.15 - Fiscal Agent obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...false Fiscal Agent obligations. 221.15 Section 221.15 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS AND CONDITIONS The Guarantee § 221.15 Fiscal Agent obligations. Failure of the...

  7. 22 CFR 221.15 - Fiscal Agent obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Fiscal Agent obligations. 221.15 Section 221.15 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS AND CONDITIONS The Guarantee § 221.15 Fiscal Agent obligations. Failure of the...

  8. Divine voluntarism: moral obligation supervenes on God's antecedent will

    E-print Network

    Nam, Mi Young

    2004-11-15

    undesirable implications, e.g., that moral obligation is arbitrary and that God's goodness is trivial. Also, while it avoids these undesirable implications, divine voluntarism must not imply that God is, in some way, restricted by moral obligation which exists...

  9. 47 CFR 24.247 - Triggering a reimbursement obligation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...reimbursement obligation. 24.247 Section 24.247 Telecommunication FEDERAL COMMUNICATIONS...the 1850-1990 Mhz Band § 24.247 Triggering a reimbursement obligation...1996, as amended at 62 FR 12757, Mar. 18, 1997; 69 FR 67836,...

  10. 47 CFR 24.247 - Triggering a reimbursement obligation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...reimbursement obligation. 24.247 Section 24.247 Telecommunication FEDERAL COMMUNICATIONS...the 1850-1990 Mhz Band § 24.247 Triggering a reimbursement obligation...1996, as amended at 62 FR 12757, Mar. 18, 1997; 69 FR 67836,...

  11. 47 CFR 24.247 - Triggering a reimbursement obligation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...reimbursement obligation. 24.247 Section 24.247 Telecommunication FEDERAL COMMUNICATIONS...the 1850-1990 Mhz Band § 24.247 Triggering a reimbursement obligation...1996, as amended at 62 FR 12757, Mar. 18, 1997; 69 FR 67836,...

  12. 47 CFR 24.247 - Triggering a reimbursement obligation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...reimbursement obligation. 24.247 Section 24.247 Telecommunication FEDERAL COMMUNICATIONS...the 1850-1990 Mhz Band § 24.247 Triggering a reimbursement obligation...1996, as amended at 62 FR 12757, Mar. 18, 1997; 69 FR 67836,...

  13. 47 CFR 24.247 - Triggering a reimbursement obligation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...reimbursement obligation. 24.247 Section 24.247 Telecommunication FEDERAL COMMUNICATIONS...the 1850-1990 Mhz Band § 24.247 Triggering a reimbursement obligation...1996, as amended at 62 FR 12757, Mar. 18, 1997; 69 FR 67836,...

  14. 29 CFR 1984.102 - Obligations and prohibited acts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Obligations and prohibited acts. 1984.102 Section 1984.102 Labor Regulations Relating to Labor (Continued...Investigations, Findings and Preliminary Orders § 1984.102 Obligations and prohibited acts....

  15. 29 CFR 1984.102 - Obligations and prohibited acts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Obligations and prohibited acts. 1984.102 Section 1984.102 Labor Regulations Relating to Labor (Continued...Investigations, Findings and Preliminary Orders § 1984.102 Obligations and prohibited acts....

  16. 38 CFR 17.608 - Deferment of obligated service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...obligated service. (a) Request for deferment. A participant receiving a degree from a school of medicine, osteopathy, dentistry, optometry, or podiatry, may request deferment of obligated service to complete an approved program of advanced...

  17. 38 CFR 17.608 - Deferment of obligated service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...obligated service. (a) Request for deferment. A participant receiving a degree from a school of medicine, osteopathy, dentistry, optometry, or podiatry, may request deferment of obligated service to complete an approved program of advanced...

  18. 38 CFR 17.608 - Deferment of obligated service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...obligated service. (a) Request for deferment. A participant receiving a degree from a school of medicine, osteopathy, dentistry, optometry, or podiatry, may request deferment of obligated service to complete an approved program of advanced...

  19. 38 CFR 17.608 - Deferment of obligated service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...obligated service. (a) Request for deferment. A participant receiving a degree from a school of medicine, osteopathy, dentistry, optometry, or podiatry, may request deferment of obligated service to complete an approved program of advanced...

  20. 38 CFR 17.608 - Deferment of obligated service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...obligated service. (a) Request for deferment. A participant receiving a degree from a school of medicine, osteopathy, dentistry, optometry, or podiatry, may request deferment of obligated service to complete an approved program of advanced...

  1. 18 CFR 35.18 - Asset retirement obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...components related to the asset retirement obligations...components related to asset retirement obligations...depreciation and accumulated deferred income taxes, may not be reflected...base costs related to asset retirement costs in...

  2. 18 CFR 154.315 - Asset retirement obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...components related to the asset retirement obligations...components related to asset retirement obligations...depreciation and accumulated deferred income taxes, may not be reflected...base costs related to asset retirement...

  3. 18 CFR 154.315 - Asset retirement obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...components related to the asset retirement obligations...components related to asset retirement obligations...depreciation and accumulated deferred income taxes, may not be reflected...base costs related to asset retirement...

  4. 18 CFR 35.18 - Asset retirement obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...components related to the asset retirement obligations...components related to asset retirement obligations...depreciation and accumulated deferred income taxes, may not be reflected...base costs related to asset retirement costs in...

  5. 29 CFR 4043.20 - Post-Event filing obligation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 2010-07-01 false Post-Event filing obligation. 4043.20 ...AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events § 4043.20 Post-Event filing obligation. The plan...

  6. 47 CFR 51.703 - Reciprocal compensation obligation of LECs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Reciprocal compensation obligation of LECs. 51... FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER...INTERCONNECTION Reciprocal Compensation for Transport and Termination... § 51.703 Reciprocal compensation obligation of LECs....

  7. Lateral phage transfer in obligate intracellular bacteria (Wolbachia): Verification from natural populations

    E-print Network

    Bordenstein, Seth

    and methods, but not Abstract: 11,132 Number of references 30 #12;Abstract. Lateral transfer of mobile DNA that bacteriophage WO-B transfers laterally between infections of the same insect host. Lateral transfer between strains. Here we analyze bacterial and phage genes from two pairs of natural sympatric field isolates

  8. Intervention of Phytohormone Pathways by Pathogen Effectors[OPEN

    PubMed Central

    Kazan, Kemal; Lyons, Rebecca

    2014-01-01

    The constant struggle between plants and microbes has driven the evolution of multiple defense strategies in the host as well as offense strategies in the pathogen. To defend themselves from pathogen attack, plants often rely on elaborate signaling networks regulated by phytohormones. In turn, pathogens have adopted innovative strategies to manipulate phytohormone-regulated defenses. Tactics frequently employed by plant pathogens involve hijacking, evading, or disrupting hormone signaling pathways and/or crosstalk. As reviewed here, this is achieved mechanistically via pathogen-derived molecules known as effectors, which target phytohormone receptors, transcriptional activators and repressors, and other components of phytohormone signaling in the host plant. Herbivores and sap-sucking insects employ obligate pathogens such as viruses, phytoplasma, or symbiotic bacteria to intervene with phytohormone-regulated defenses. Overall, an improved understanding of phytohormone intervention strategies employed by pests and pathogens during their interactions with plants will ultimately lead to the development of new crop protection strategies. PMID:24920334

  9. A Toxoplasma gondii protein with homology to intracellular type Na +\\/H + exchangers is important for osmoregulation and invasion

    Microsoft Academic Search

    Maria E. Francia; Sarah Wicher; Douglas A. Pace; Jack Sullivan; Silvia N. J. Moreno; Gustavo Arrizabalaga

    2011-01-01

    The obligate intracellular parasite Toxoplasma gondii is exposed to a variety of physiological conditions while propagating in an infected organism. The mechanisms by which Toxoplasma overcomes these dramatic changes in its environment are not known. In yeast and plants, ion detoxification and osmotic regulation are controlled by vacuolar compartments. A novel compartment named the plant-like vacuole or vacuolar compartment (PLV\\/VAC)

  10. 7 CFR 1488.12 - Coverage of bank obligations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Coverage of bank obligations. 1488.12 Section 1488...Export Credit Sales Program (GSM-5) Bank Obligations and Repayment § 1488.12 Coverage of bank obligations. (a) U.S. banks and...

  11. 34 CFR 686.43 - Obligation to repay the grant.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Obligation to repay the grant. 686.43 Section 686.43 Education...FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.43 Obligation to repay the grant. (a) The TEACH Grant amounts...

  12. 34 CFR 686.43 - Obligation to repay the grant.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Obligation to repay the grant. 686.43 Section 686.43 Education...FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.43 Obligation to repay the grant. (a) The TEACH Grant amounts...

  13. 34 CFR 686.43 - Obligation to repay the grant.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Obligation to repay the grant. 686.43 Section 686.43 Education...FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.43 Obligation to repay the grant. (a) The TEACH Grant amounts...

  14. 34 CFR 686.43 - Obligation to repay the grant.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Obligation to repay the grant. 686.43 Section 686.43 Education...FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.43 Obligation to repay the grant. (a) The TEACH Grant amounts...

  15. 34 CFR 686.43 - Obligation to repay the grant.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Obligation to repay the grant. 686.43 Section 686.43 Education...FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.43 Obligation to repay the grant. (a) The TEACH Grant amounts...

  16. Invasion and Intracellular Survival by Protozoan Parasites

    PubMed Central

    Sibley, L. David

    2013-01-01

    Summary Intracellular parasitism has arisen only a few times during the long ancestry of protozoan parasites including in diverse groups such as microsporidians, kinetoplastids, and apicomplexans. Strategies used to gain entry differ widely from injection (e.g. microsporidians), active penetration of the host cell (e.g. Toxoplasma), recruitment of lysosomes to a plasma membrane wound (e.g. Trypanosoma cruzi), to host cell-mediated phagocytosis (e.g. Leishmania). The resulting range of intracellular niches is equally diverse ranging from cytosolic (e.g. T. cruzi) to residing within a nonfusigenic vacuole (e.g. Toxoplasma, Encephalitizoon) or a modified phagolysosome (e.g. Leishmania). These lifestyle choices influence access to nutrients, interaction with host cell signaling pathways, and detection by pathogen recognition systems. As such, intracellular life requires a repertoire of adaptations to assure entry-exit from the cell, as well as to thwart innate immune mechanisms and prevent clearance. Elucidating these pathways at the cellular and molecular level may identify key steps that can be targeted to reduce parasite survival or augment immunological responses and thereby prevent disease. PMID:21349087

  17. Proteomics of Plant Pathogenic Fungi

    PubMed Central

    González-Fernández, Raquel; Prats, Elena; Jorrín-Novo, Jesús V.

    2010-01-01

    Plant pathogenic fungi cause important yield losses in crops. In order to develop efficient and environmental friendly crop protection strategies, molecular studies of the fungal biological cycle, virulence factors, and interaction with its host are necessary. For that reason, several approaches have been performed using both classical genetic, cell biology, and biochemistry and the modern, holistic, and high-throughput, omic techniques. This work briefly overviews the tools available for studying Plant Pathogenic Fungi and is amply focused on MS-based Proteomics analysis, based on original papers published up to December 2009. At a methodological level, different steps in a proteomic workflow experiment are discussed. Separate sections are devoted to fungal descriptive (intracellular, subcellular, extracellular) and differential expression proteomics and interactomics. From the work published we can conclude that Proteomics, in combination with other techniques, constitutes a powerful tool for providing important information about pathogenicity and virulence factors, thus opening up new possibilities for crop disease diagnosis and crop protection. PMID:20589070

  18. 40 CFR 80.1107 - How is the Renewable Volume Obligation calculated?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false How is the Renewable Volume Obligation calculated? 80.1107 Section...Standard § 80.1107 How is the Renewable Volume Obligation calculated? (a) The Renewable Volume Obligation for an obligated party is...

  19. 40 CFR 80.1107 - How is the Renewable Volume Obligation calculated?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false How is the Renewable Volume Obligation calculated? 80.1107 Section...Standard § 80.1107 How is the Renewable Volume Obligation calculated? (a) The Renewable Volume Obligation for an obligated party is...

  20. 40 CFR 80.1107 - How is the Renewable Volume Obligation calculated?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false How is the Renewable Volume Obligation calculated? 80.1107 Section...Standard § 80.1107 How is the Renewable Volume Obligation calculated? (a) The Renewable Volume Obligation for an obligated party is...

  1. 40 CFR 80.1107 - How is the Renewable Volume Obligation calculated?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false How is the Renewable Volume Obligation calculated? 80.1107 Section...Standard § 80.1107 How is the Renewable Volume Obligation calculated? (a) The Renewable Volume Obligation for an obligated party is...

  2. 40 CFR 80.1107 - How is the Renewable Volume Obligation calculated?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false How is the Renewable Volume Obligation calculated? 80.1107 Section...Standard § 80.1107 How is the Renewable Volume Obligation calculated? (a) The Renewable Volume Obligation for an obligated party is...

  3. ELECTRICAL STIMULATION RESEARCH TECHNIQUES Intracellular Stimulation

    E-print Network

    Byrne, John H.

    ELECTRICAL STIMULATION RESEARCH TECHNIQUES Chapter 2 Intracellular Stimulation John H. Byrne Introduction . . . . . . . . . 37 II. Intracellular Stimulation and Recording with Separate Electrodes 38 Ill. A Simple Circuit for Intracellular Stimulation with Two Electrodes 42 IV. Intracellular Stimulation

  4. Fungal Pathogens: Survival and Replication within Macrophages.

    PubMed

    Gilbert, Andrew S; Wheeler, Robert T; May, Robin C

    2014-11-10

    The innate immune system is a critical line of defense against pathogenic fungi. Macrophages act at an early stage of infection, detecting and phagocytizing infectious propagules. To avoid killing at this stage, fungal pathogens use diverse strategies ranging from evasion of uptake to intracellular parasitism. This article will discuss five of the most important human fungal pathogens (Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, Coccidiodes immitis, and Histoplasma capsulatum) and consider the strategies and virulence factors adopted by each to survive and replicate within macrophages. PMID:25384769

  5. Nanovehicular Intracellular Delivery Systems

    PubMed Central

    PROKOP, ALES; DAVIDSON, JEFFREY M.

    2013-01-01

    This article provides an overview of principles and barriers relevant to intracellular drug and gene transport, accumulation and retention (collectively called as drug delivery) by means of nanovehicles (NV). The aim is to deliver a cargo to a particular intracellular site, if possible, to exert a local action. Some of the principles discussed in this article apply to noncolloidal drugs that are not permeable to the plasma membrane or to the blood–brain barrier. NV are defined as a wide range of nanosized particles leading to colloidal objects which are capable of entering cells and tissues and delivering a cargo intracelullarly. Different localization and targeting means are discussed. Limited discussion on pharmacokinetics and pharmacodynamics is also presented. NVs are contrasted to micro-delivery and current nanotechnologies which are already in commercial use. Newer developments in NV technologies are outlined and future applications are stressed. We also briefly review the existing modeling tools and approaches to quantitatively describe the behavior of targeted NV within the vascular and tumor compartments, an area of particular importance. While we list “elementary” phenomena related to different level of complexity of delivery to cancer, we also stress importance of multi-scale modeling and bottom-up systems biology approach. PMID:18200527

  6. Subversion of inflammasome activation and pyroptosis by pathogenic bacteria

    PubMed Central

    Cunha, Larissa D.; Zamboni, Dario S.

    2013-01-01

    Activation of the inflammasome occurs in response to a notably high number of pathogenic microbes and is a broad innate immune response that effectively contributes to restriction of pathogen replication and generation of adaptive immunity. Activation of these platforms leads to caspase-1- and/or caspase-11-dependent secretion of proteins, including cytokines, and induction of a specific form of cell death called pyroptosis, which directly or indirectly contribute for restriction of pathogen replication. Not surprisingly, bona fide intracellular pathogens developed strategies for manipulation of cell death to guarantee intracellular replication. In this sense, the remarkable advances in the knowledge of the inflammasome field have been accompanied by several reports characterizing the inhibition of this platform by several pathogenic bacteria. Herein, we review some processes used by pathogenic bacteria, including Yersinia spp., Pseudomonas aeruginosa, Vibrio parahaemolyticus, Chlamydia trachomatis, Francisella tularensis, Shigella flexneri, Legionella pneumophila, and Coxiella burnetii to evade the activation of the inflammasome and the induction of pyroptosis. PMID:24324933

  7. Intracellular sensing of complement C3 activates cell autonomous immunity

    PubMed Central

    Tam, Jerry C.H.; Bidgood, Susanna R.; McEwan, William A.; James, Leo C.

    2014-01-01

    Pathogens traverse multiple barriers during infection including cell membranes. Here we show that during this transition pathogens carry covalently attached complement C3 into the cell, triggering immediate signalling and effector responses. Sensing of C3 in the cytosol activates MAVS-dependent signalling cascades and induces proinflammatory cytokine secretion. C3 also flags viruses for rapid proteasomal degradation, thereby preventing their replication. This system can detect both viral and bacterial pathogens but is antagonized by enteroviruses, such as rhinovirus and poliovirus, which cleave C3 using their 3C protease. The antiviral Rupintrivir inhibits 3C protease and prevents C3 cleavage, rendering enteroviruses susceptible to intracellular complement sensing. Thus, complement C3 allows cells to detect and disable pathogens that have invaded the cytosol. PMID:25190799

  8. Cationic Antimicrobial Peptide LL-37 Is Effective against both Extra- and Intracellular Staphylococcus aureus

    PubMed Central

    Noore, Jabeen; Noore, Adly

    2013-01-01

    The increasing resistance of bacteria to conventional antibiotics and the challenges posed by intracellular bacteria, which may be responsible for chronic and recurrent infections, have driven the need for advanced antimicrobial drugs for effective elimination of both extra- and intracellular pathogens. The purpose of this study was to determine the killing efficacy of cationic antimicrobial peptide LL-37 compared to conventional antibiotics against extra- and intracellular Staphylococcus aureus. Bacterial killing assays and an infection model of osteoblasts and S. aureus were studied to determine the bacterial killing efficacy of LL-37 and conventional antibiotics against extra- and intracellular S. aureus. We found that LL-37 was effective in killing extracellular S. aureus at nanomolar concentrations, while lactoferricin B was effective at micromolar concentrations and doxycycline and cefazolin at millimolar concentrations. LL-37 was surprisingly more effective in killing the clinical strain than in killing an ATCC strain of S. aureus. Moreover, LL-37 was superior to conventional antibiotics in eliminating intracellular S. aureus. The kinetic studies further revealed that LL-37 was fast in eliminating both extra- and intracellular S. aureus. Therefore, LL-37 was shown to be very potent and prompt in eliminating both extra- and intracellular S. aureus and was more effective in killing extra- and intracellular S. aureus than commonly used conventional antibiotics. LL-37 could potentially be used to treat chronic and recurrent infections due to its effectiveness in eliminating not only extracellular but also intracellular pathogens. PMID:23274662

  9. Obligate biotrophy features unraveled by the genomic analysis of the rust fungi, Melampsora larici-populina and Puccinia graminis f. sp. tritici

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rust fungi are some of the most devastating pathogens of crop plants. They are obligate biotrophs, which extract nutrients only from living plant tissues and cannot grow apart from their hosts. Their lifestyle has slowed the dissection of molecular mechanisms underlying host invasion and avoidance...

  10. Carbon based nutrition of Staphylococcus aureus and the role of sugar phosphate transporters in intracellular bacterial replication 

    E-print Network

    Bell, John Alexander

    2014-06-28

    The Gram positive bacterium Staphylococcus aureus is a major cause of human disease in industrialized countries. This multifaceted pathogen is adapted to thrive in a variety of host niches, including the intracellular ...

  11. Heat tolerance of free living and of intracellular Listeria.

    PubMed

    Ly, T M; Müller, H E

    1989-12-01

    Listeria monocytogenes, L. innocua, and L. seeligeri are ingested by Tetrahymena pyriformis. They are not killed but survive and lyse bacteriovorous protozoans after about 8 days. The question important in food processing whether intracellular L. monocytogenes are protected against pasteurization was investigated using a model of Tetrahymena containing previously ingested Listeria. The study showed that Tetrahymena containing Listeria are more susceptible against application of heat, but intracellular Listeria, phagocytized within Tetrahymena, are not more protected than free and extracellular bacteria. Therefore, a properly performed pasteurization, i.e. of milk, kills intracellular Listeria as fast as extracellular living organisms. Finally, the pathogenic L. monocytogenes showed a higher susceptibility and lower tolerance against application of heat than apathogenic L. innocua and L. seeligeri. PMID:2516720

  12. Intracellular Salmonella inhibit antigen presentation by dendritic cells.

    PubMed

    Cheminay, Cédric; Möhlenbrink, Annette; Hensel, Michael

    2005-03-01

    Dendritic cells (DC) are important APCs linking innate and adaptive immunity. During analysis of the intracellular activities of Salmonella enterica in DC, we observed that viable bacteria suppress Ag-dependent T cell proliferation. This effect was dependent on the induction of inducible NO synthase by DC and on the function of virulence genes in Salmonella pathogenicity island 2 (SPI2). Intracellular activities of Salmonella did not affect the viability, Ag uptake, or maturation of DC, but resulted in reduced presentation of antigenic peptides by MHC class II molecules. Increased resistance to reinfection was observed after vaccination of mice with SPI2-deficient Salmonella compared with mice vaccinated with SPI2-proficient Salmonella, and this correlated with an increased amount of CD4(+) as well as CD8(+) T cells. Our study is the first example of interference of an intracellular bacterial pathogen with Ag presentation by DC. The subversion of DC functions is a novel strategy deployed by this pathogen to escape immune defense, colonize host organs, and persist in the infected host. PMID:15728500

  13. Back from the Dormant Stage: Second Messenger Cyclic ADP-Ribose Essential for Toxoplasma gondii Pathogenicity

    NSDL National Science Digital Library

    Andreas H. Guse (University Medical Centre Hamburg-Eppendorf; Institute of Biochemistry and Molecular Biology and Centre of Experimental Medicine REV)

    2008-04-29

    Cyclic adenosine diphosphoribose (cADPR) is an endogenous Ca2+-mobilizing second messenger found in cells of animals, plants, and protozoans. It is formed by a specific class of enzymes, the ADP-ribosyl cyclases. cADPR stimulates Ca2+ release by means of ryanodine receptors located in the sarcoplasmic and endoplasmic reticulum. Recently, a role for cADPR has been demonstrated in the obligate intracellular protozoan pathogen Toxoplasma gondii. In T. gondii, stress conditions evoked synthesis of the plant hormone abscisic acid by the apicoplast, a remnant organelle of an algal endosymbiont of T. gondii. Abscisic acid in turn activated formation of cADPR within T. gondii, resulting in Ca2+ release and secretion of proteins involved in egress of T. gondii from its host cell. Evidence for a synthetic pathway of plant origin was obtained with the ABA synthesis inhibitor fluridone, which antagonized cellular egress and induced differentiation of long-lived semidormant cystic forms of T. gondii. Moreover, fluridone protected mice from toxoplasmosis.

  14. The role of autophagy in the intracellular survival of Campylobacter concisus

    PubMed Central

    Burgos-Portugal, Jose A.; Mitchell, Hazel M.; Castaño-Rodríguez, Natalia; Kaakoush, Nadeem O.

    2014-01-01

    Campylobacter concisus is an emerging pathogen that has been associated with gastrointestinal diseases. Given the importance of autophagy for the elimination of intracellular bacteria and the subversion of this process by pathogenic bacteria, we investigated the role of autophagy in C. concisus intracellular survival. Gentamicin protection assays were employed to assess intracellular levels of C. concisus within Caco-2 cells, following autophagy induction and inhibition. To assess the interaction between C. concisus and autophagosomes, confocal microscopy, scanning electron microscopy, and transmission electron microscopy were employed. Expression levels of 84 genes involved in the autophagy process were measured using qPCR. Autophagy inhibition resulted in two- to four-fold increases in intracellular levels of C. concisus within Caco-2 cells, while autophagy induction resulted in a significant reduction in intracellular levels or bacterial clearance. C. concisus strains with low intracellular survival levels showed a dramatic increase in these levels upon autophagy inhibition. Confocal microscopy showed co-localization of the bacterium with autophagosomes, while transmission electron microscopy identified intracellular bacteria persisting within autophagic vesicles. Further, qPCR showed that following infection, 13 genes involved in the autophagy process were significantly regulated, and a further five showed borderline results, with an overall indication towards a dampening effect exerted by the bacterium on this process. Our data collectively indicates that while autophagy is important for the clearance of C. concisus, some strains may manipulate this process to benefit their intracellular survival. PMID:24918042

  15. Obligately barophilic bacterium from the Mariana trench.

    PubMed Central

    Yayanos, A A; Dietz, A S; Van Boxtel, R

    1981-01-01

    An amphipod (Hirondellea gigas) was retrieved with decompression in an insulated trap from an ocean depth of 10,476 m. Bacterial isolates were obtained from the dead and cold animal by using silica gel medium incubated at 1000 bars (1 bar = 10(5) Pa) and 2 degrees C. The isolate designated MT41 was found to be obligately barophilic and did not grow at a pressure close to that of 380 bars found at average depths of the sea. The optimal generation time of about 25 hr was at 2 degrees C and 690 bars. The generation time at 2 degrees C and 1,035 bars, a pressure close to that at the depth of origin, was about 33 hr. Among the conclusions are: (i) pressure is an important determinant of zonation along the water column of the sea; (ii) some obligately barophilic bacteria survive decompressions; (iii) the pressure of optimal growth at 2 degrees C appears to be less than the pressure at the depth of origin and may be diagnostic for the depth of origin; (iv) rates of reproduction are slow yet significant and an order of magnitude greater than previously thought; and (v) much of deep-sea microbiology may have been done with spurious deep-sea organisms due to warming of samples. Images PMID:6946468

  16. Experimental replacement of an obligate insect symbiont.

    PubMed

    Moran, Nancy A; Yun, Yueli

    2015-02-17

    Symbiosis, the close association of unrelated organisms, has been pivotal in biological diversification. In the obligate symbioses found in many insect hosts, organisms that were once independent are permanently and intimately associated, resulting in expanded ecological capabilities. The primary model for this kind of symbiosis is the association between the bacterium Buchnera and the pea aphid (Acyrthosiphon pisum). A longstanding obstacle to efforts to illuminate genetic changes underlying obligate symbioses has been the inability to experimentally disrupt and reconstitute symbiont-host partnerships. Our experiments show that Buchnera can be experimentally transferred between aphid matrilines and, furthermore, that Buchnera replacement has a massive effect on host fitness. Using a recipient pea aphid matriline containing Buchnera that are heat sensitive because of an allele eliminating the heat shock response of a small chaperone, we reduced native Buchnera through heat exposure and introduced a genetically distinct Buchnera from another matriline, achieving complete replacement and stable inheritance. This transfer disrupted 100 million years (?1 billion generations) of continuous maternal transmission of Buchnera in its host aphids. Furthermore, aphids with the Buchnera replacement enjoyed a dramatic increase in heat tolerance, directly demonstrating a strong effect of symbiont genotype on host ecology. PMID:25561531

  17. Characterization of an ATP translocase identified in the plant pathogen, Candidatus Liberibacter asiaticus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ATP/ADP translocases allow for the transport of ATP across a lipid bilayer, which is normally impermeable to this molecule due to its size and charge. These transport proteins appear to be unique to mitochondria, plant plastids, and obligate-intracellular bacteria. Of the bacterial ATP/ADP translo...

  18. Metabolism of the vacuolar pathogen Legionella and implications for virulence

    PubMed Central

    Manske, Christian; Hilbi, Hubert

    2014-01-01

    Legionella pneumophila is a ubiquitous environmental bacterium that thrives in fresh water habitats, either as planktonic form or as part of biofilms. The bacteria also grow intracellularly in free-living protozoa as well as in mammalian alveolar macrophages, thus triggering a potentially fatal pneumonia called “Legionnaires' disease.” To establish its intracellular niche termed the “Legionella-containing vacuole” (LCV), L. pneumophila employs a type IV secretion system and translocates ~300 different “effector” proteins into host cells. The pathogen switches between two distinct forms to grow in its extra- or intracellular niches: transmissive bacteria are virulent for phagocytes, and replicative bacteria multiply within their hosts. The switch between these forms is regulated by different metabolic cues that signal conditions favorable for replication or transmission, respectively, causing a tight link between metabolism and virulence of the bacteria. Amino acids represent the prime carbon and energy source of extra- or intracellularly growing L. pneumophila. Yet, the genome sequences of several Legionella spp. as well as transcriptome and proteome data and metabolism studies indicate that the bacteria possess broad catabolic capacities and also utilize carbohydrates such as glucose. Accordingly, L. pneumophila mutant strains lacking catabolic genes show intracellular growth defects, and thus, intracellular metabolism and virulence of the pathogen are intimately connected. In this review we will summarize recent findings on the extra- and intracellular metabolism of L. pneumophila using genetic, biochemical and cellular microbial approaches. Recent progress in this field sheds light on the complex interplay between metabolism, differentiation and virulence of the pathogen. PMID:25250244

  19. Modulation of pathogen recognition by autophagy.

    PubMed

    Oh, Ji Eun; Lee, Heung Kyu

    2012-01-01

    Autophagy is an ancient biological process for maintaining cellular homeostasis by degradation of long-lived cytosolic proteins and organelles. Recent studies demonstrated that autophagy is availed by immune cells to regulate innate immunity. On the one hand, cells exert direct effector function by degrading intracellular pathogens; on the other hand, autophagy modulates pathogen recognition and downstream signaling for innate immune responses. Pathogen recognition via pattern recognition receptors induces autophagy. The function of phagocytic cells is enhanced by recruitment of autophagy-related proteins. Moreover, autophagy acts as a delivery system for viral replication complexes to migrate to the endosomal compartments where virus sensing occurs. In another case, key molecules of the autophagic pathway have been found to negatively regulate immune signaling, thus preventing aberrant activation of cytokine production and consequent immune responses. In this review, we focus on the recent advances in the role of autophagy in pathogen recognition and modulation of innate immune responses. PMID:22566926

  20. INTRACELLULAR SIGNALING AND DEVELOPMENTAL NEUROTOXICITY.

    EPA Science Inventory

    A book chapter in ?Molecular Toxicology: Transcriptional Targets? reviewed the role of intracellular signaling in the developmental neurotoxicity of environmental chemicals. This chapter covered a number of aspects including the development of the nervous system, role of intrace...

  1. Importance of branched-chain amino acid utilization in Francisella intracellular adaptation.

    PubMed

    Gesbert, Gael; Ramond, Elodie; Tros, Fabiola; Dairou, Julien; Frapy, Eric; Barel, Monique; Charbit, Alain

    2015-01-01

    Intracellular bacterial pathogens have adapted their metabolism to optimally utilize the nutrients available in infected host cells. We recently reported the identification of an asparagine transporter required specifically for cytosolic multiplication of Francisella. In the present work, we characterized a new member of the major super family (MSF) of transporters, involved in isoleucine uptake. We show that this transporter (here designated IleP) plays a critical role in intracellular metabolic adaptation of Francisella. Inactivation of IleP severely impaired intracellular F. tularensis subsp. novicida multiplication in all cell types tested and reduced bacterial virulence in the mouse model. To further establish the importance of the ileP gene in F. tularensis pathogenesis, we constructed a chromosomal deletion mutant of ileP (?FTL_1803) in the F. tularensis subsp. holarctica live vaccine strain (LVS). Inactivation of IleP in the F. tularensis LVS provoked comparable intracellular growth defects, confirming the critical role of this transporter in isoleucine uptake. The data presented establish, for the first time, the importance of isoleucine utilization for efficient phagosomal escape and cytosolic multiplication of Francisella and suggest that virulent F. tularensis subspecies have lost their branched-chain amino acid biosynthetic pathways and rely exclusively on dedicated uptake systems. This loss of function is likely to reflect an evolution toward a predominantly intracellular life style of the pathogen. Amino acid transporters should be thus considered major players in the adaptation of intracellular pathogens. PMID:25332124

  2. Standard of care, institutional obligations, and distributive justice.

    PubMed

    MacKay, Douglas

    2015-05-01

    The problem of standard of care in clinical research concerns the level of treatment that investigators must provide to subjects in clinical trials. Commentators often formulate answers to this problem by appealing to two distinct types of obligations: professional obligations and natural duties. In this article, I investigate whether investigators also possess institutional obligations that are directly relevant to the problem of standard of care, that is, those obligations a person has because she occupies a particular institutional role. I examine two types of institutional contexts: (1) public research agencies - agencies or departments of states that fund or conduct clinical research in the public interest; and (2) private-for-profit corporations. I argue that investigators who are employed or have their research sponsored by the former have a distinctive institutional obligation to conduct their research in a way that is consistent with the state's duty of distributive justice to provide its citizens with access to basic health care, and its duty to aid citizens of lower income countries. By contrast, I argue that investigators who are employed or have their research sponsored by private-for-profit corporations do not possess this obligation nor any other institutional obligation that is directly relevant to the ethics of RCTs. My account of the institutional obligations of investigators aims to contribute to the development of a reasonable, distributive justice-based account of standard of care. PMID:24117682

  3. Cultural Generality of the Integration of Obligation and Other Motives

    ERIC Educational Resources Information Center

    Yang, Jen-Shou

    2012-01-01

    The purpose of the present study is twofold. One is to assess the cultural generality of the information integration rule for moral obligation. The other is to examine how people integrate moral obligation and self-interest. Two studies were implemented following the functional measurement methodology with Chinese samples. Study 1 replicated the…

  4. The Evolutionary Pathway to Obligate Scavenging in Gyps Vultures

    Microsoft Academic Search

    Brian J. Dermody; Colby J. Tanner; Andrew L. Jackson

    2011-01-01

    The evolutionary pathway to obligate scavenging in Gyps vultures remains unclear. We propose that communal roosting plays a central role in setting up the information transfer network critical for obligate scavengers in ephemeral environments and that the formation of a flotilla-like foraging group is a likely strategy for foraging Gyps vultures. Using a spatial, individual-based, optimisation model we find that

  5. Deconfounding Distance Effects in Judgments of Moral Obligation

    ERIC Educational Resources Information Center

    Nagel, Jonas; Waldmann, Michael R.

    2013-01-01

    A heavily disputed question of moral philosophy is whether spatial distance between agent and victim is normatively relevant for the degree of obligation to help strangers in need. In this research, we focus on the associated descriptive question whether increased distance does in fact reduce individuals' sense of helping obligation. One problem…

  6. The Role Obligations of Students and Lecturers in Higher Education

    ERIC Educational Resources Information Center

    Regan, Julie-Anne

    2012-01-01

    The current discussion of consumerism in higher education focuses largely on what the providers are obliged to do for the consumers, against the background of rising tuition fees. This framework does not always sit comfortably with lecturers in the context of a learning and teaching relationship, as it appears to ignore the reciprocal obligations

  7. Energy Saving Obligations Cutting the Gordian Knot of leverage?

    E-print Network

    Paris-Sud XI, Université de

    leverage and additionality. KEYWORDS Energy Savings Obligation, Leverage, Financing hal-01016112,version1 and there was no requirement for member states to implement the instrument. This has now changed: The new Energy Efficiency1 Energy Saving Obligations Cutting the Gordian Knot of leverage? Pre-print version to appear

  8. In Defence of Associative Political Obligations: Part One

    Microsoft Academic Search

    John Horton

    2007-01-01

    Part One of this article seeks to defend the idea of associative political obligations against a number of criticisms that have been advanced opposing it.The purpose of this defence is not to demonstrate that the associative account is therefore the best explanation of political obligations, but only that the principal reasons which have been given for rejecting it are much

  9. Opportunism and competition in the non-fossil fuel obligation

    E-print Network

    Watson, Andrew

    Opportunism and competition in the non-fossil fuel obligation Paolo Agnolucci July 2005 Tyndall are the responsibility of the author(s) alone and not the Tyndall Centre. #12;Summary The Non-Fossil Fuel Order (NFFO Electricity; Renewable Policy, Non-Fossil Fuel Obligation; Moral Hazard; Post-contractual Opportunism #12

  10. Parental Beliefs about Nonresident Fathers' Obligations and Rights

    ERIC Educational Resources Information Center

    Lin, I-Fen; McLanahan, Sara S.

    2007-01-01

    We examine whether parents rely on principles of equity or equality in making judgments about nonresident fathers' obligations and rights. The data are taken from the first wave of the Fragile Families and Child Wellbeing Study. The analysis sample includes 4,304 new mothers and 3,414 new fathers. Results indicate that fathers perceive obligations

  11. Daughters’ Obligation to Care in the Context of Past Abuse

    Microsoft Academic Search

    Judith Wuest; Jean Malcolm; Marilyn Merritt-Gray

    2010-01-01

    Using theoretical sampling, we extended a previous grounded theory study of women's caring through interviews with 16 women currently giving care to parents who had abused them as children to more fully understand daughters’ obligation to care in the context of past abuse. Past relationship was characterized by emotional distance, “never being good enough,” degradation, control, and unpredictability. Obligation to

  12. Schooling properties of an obligate and a facultative fish species

    E-print Network

    Paris-Sud XI, Université de

    Schooling properties of an obligate and a facultative fish species M. SORIA* , P. FREON § and P, Nouvelle-Calédonie, France Schooling fish species are conventionally subdivided into obligate interactions, Schooling behaviour, Polarity, Pelagic fish Running headline: Schooling properties of two fish

  13. 7 CFR 1488.12 - Coverage of bank obligations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Commodities From Private Stocks Under CCC Export Credit Sales Program (GSM-5) Bank Obligations and Repayment § 1488.12 Coverage...obligation. (j) Collection of accounts receivable purchased under GSM-5 will be effected through the issuance by CCC of sight...

  14. 12 CFR 987.8 - Additional requirements; notice of attachment for Book-entry consolidated obligations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...requirements; notice of attachment for Book-entry consolidated obligations. 987...HOUSING FINANCE BOARD OFFICE OF FINANCE BOOK-ENTRY PROCEDURE FOR CONSOLIDATED OBLIGATIONS...requirements; notice of attachment for Book-entry consolidated obligations....

  15. 12 CFR 1270.18 - Additional requirements; notice of attachment for Book-entry consolidated obligations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...requirements; notice of attachment for Book-entry consolidated obligations. 1270...FEDERAL HOME LOAN BANKS LIABILITIES Book-Entry Procedure for Consolidated Obligations...requirements; notice of attachment for Book-entry consolidated obligations....

  16. 12 CFR 1270.18 - Additional requirements; notice of attachment for Book-entry consolidated obligations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...requirements; notice of attachment for Book-entry consolidated obligations. 1270...FEDERAL HOME LOAN BANKS LIABILITIES Book-Entry Procedure for Consolidated Obligations...requirements; notice of attachment for Book-entry consolidated obligations....

  17. 12 CFR 987.8 - Additional requirements; notice of attachment for Book-entry consolidated obligations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...requirements; notice of attachment for Book-entry consolidated obligations. 987...HOUSING FINANCE BOARD OFFICE OF FINANCE BOOK-ENTRY PROCEDURE FOR CONSOLIDATED OBLIGATIONS...requirements; notice of attachment for Book-entry consolidated obligations....

  18. 12 CFR 1270.18 - Additional requirements; notice of attachment for Book-entry consolidated obligations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...requirements; notice of attachment for Book-entry consolidated obligations. 1270...FEDERAL HOME LOAN BANKS LIABILITIES Book-Entry Procedure for Consolidated Obligations...requirements; notice of attachment for Book-entry consolidated obligations....

  19. 42 CFR 1001.1501 - Default of health education loan or scholarship obligations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Default of health education loan or scholarship obligations. 1001.1501 Section... Default of health education loan or scholarship obligations. (a) Circumstance for...determines is in default on repayments of scholarship obligations or loans in...

  20. 42 CFR 1001.1501 - Default of health education loan or scholarship obligations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Default of health education loan or scholarship obligations. 1001.1501 Section... Default of health education loan or scholarship obligations. (a) Circumstance for...determines is in default on repayments of scholarship obligations or loans in...

  1. 42 CFR 1001.1501 - Default of health education loan or scholarship obligations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Default of health education loan or scholarship obligations. 1001.1501 Section... Default of health education loan or scholarship obligations. (a) Circumstance for...determines is in default on repayments of scholarship obligations or loans in...

  2. 42 CFR 1001.1501 - Default of health education loan or scholarship obligations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Default of health education loan or scholarship obligations. 1001.1501 Section... Default of health education loan or scholarship obligations. (a) Circumstance for...determines is in default on repayments of scholarship obligations or loans in...

  3. 42 CFR 1001.1501 - Default of health education loan or scholarship obligations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Default of health education loan or scholarship obligations. 1001.1501 Section... Default of health education loan or scholarship obligations. (a) Circumstance for...determines is in default on repayments of scholarship obligations or loans in...

  4. 31 CFR 225.9 - Return of Government obligations to obligor.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Return of Government obligations to obligor. 225... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.9 Return of Government obligations to obligor....

  5. 31 CFR 225.9 - Return of Government obligations to obligor.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Return of Government obligations to obligor. 225... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.9 Return of Government obligations to obligor....

  6. 31 CFR 225.9 - Return of Government obligations to obligor.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Return of Government obligations to obligor. 225... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.9 Return of Government obligations to obligor....

  7. 31 CFR 225.9 - Return of Government obligations to obligor.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Return of Government obligations to obligor. 225... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.9 Return of Government obligations to obligor....

  8. 31 CFR 225.9 - Return of Government obligations to obligor.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Return of Government obligations to obligor. 225... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.9 Return of Government obligations to obligor....

  9. A Lack of Parasitic Reduction in the Obligate Parasitic Green Alga Helicosporidium

    PubMed Central

    Pombert, Jean-François; Blouin, Nicolas Achille; Lane, Chris; Boucias, Drion; Keeling, Patrick J.

    2014-01-01

    The evolution of an obligate parasitic lifestyle is often associated with genomic reduction, in particular with the loss of functions associated with increasing host-dependence. This is evident in many parasites, but perhaps the most extreme transitions are from free-living autotrophic algae to obligate parasites. The best-known examples of this are the apicomplexans such as Plasmodium, which evolved from algae with red secondary plastids. However, an analogous transition also took place independently in the Helicosporidia, where an obligate parasite of animals with an intracellular infection mechanism evolved from algae with green primary plastids. We characterised the nuclear genome of Helicosporidium to compare its transition to parasitism with that of apicomplexans. The Helicosporidium genome is small and compact, even by comparison with the relatively small genomes of the closely related green algae Chlorella and Coccomyxa, but at the functional level we find almost no evidence for reduction. Nearly all ancestral metabolic functions are retained, with the single major exception of photosynthesis, and even here reduction is not complete. The great majority of genes for light-harvesting complexes, photosystems, and pigment biosynthesis have been lost, but those for other photosynthesis-related functions, such as Calvin cycle, are retained. Rather than loss of whole function categories, the predominant reductive force in the Helicosporidium genome is a contraction of gene family complexity, but even here most losses affect families associated with genome maintenance and expression, not functions associated with host-dependence. Other gene families appear to have expanded in response to parasitism, in particular chitinases, including those predicted to digest the chitinous barriers of the insect host or remodel the cell wall of Helicosporidium. Overall, the Helicosporidium genome presents a fascinating picture of the early stages of a transition from free-living autotroph to parasitic heterotroph where host-independence has been unexpectedly preserved. PMID:24809511

  10. A lack of parasitic reduction in the obligate parasitic green alga Helicosporidium.

    PubMed

    Pombert, Jean-François; Blouin, Nicolas Achille; Lane, Chris; Boucias, Drion; Keeling, Patrick J

    2014-05-01

    The evolution of an obligate parasitic lifestyle is often associated with genomic reduction, in particular with the loss of functions associated with increasing host-dependence. This is evident in many parasites, but perhaps the most extreme transitions are from free-living autotrophic algae to obligate parasites. The best-known examples of this are the apicomplexans such as Plasmodium, which evolved from algae with red secondary plastids. However, an analogous transition also took place independently in the Helicosporidia, where an obligate parasite of animals with an intracellular infection mechanism evolved from algae with green primary plastids. We characterised the nuclear genome of Helicosporidium to compare its transition to parasitism with that of apicomplexans. The Helicosporidium genome is small and compact, even by comparison with the relatively small genomes of the closely related green algae Chlorella and Coccomyxa, but at the functional level we find almost no evidence for reduction. Nearly all ancestral metabolic functions are retained, with the single major exception of photosynthesis, and even here reduction is not complete. The great majority of genes for light-harvesting complexes, photosystems, and pigment biosynthesis have been lost, but those for other photosynthesis-related functions, such as Calvin cycle, are retained. Rather than loss of whole function categories, the predominant reductive force in the Helicosporidium genome is a contraction of gene family complexity, but even here most losses affect families associated with genome maintenance and expression, not functions associated with host-dependence. Other gene families appear to have expanded in response to parasitism, in particular chitinases, including those predicted to digest the chitinous barriers of the insect host or remodel the cell wall of Helicosporidium. Overall, the Helicosporidium genome presents a fascinating picture of the early stages of a transition from free-living autotroph to parasitic heterotroph where host-independence has been unexpectedly preserved. PMID:24809511

  11. The Evolution of Genomic Instability in the Obligate Endosymbionts of Whiteflies

    PubMed Central

    Sloan, Daniel B.; Moran, Nancy A.

    2013-01-01

    Many insects depend on ancient associations with intracellular bacteria to perform essential metabolic functions. These endosymbionts exhibit striking examples of convergence in genome architecture, including a high degree of structural stability that is not typical of their free-living counterparts. However, the recently sequenced genome of the obligate whitefly endosymbiont Portiera revealed features that distinguish it from other ancient insect associates, such as a low gene density and the presence of perfectly duplicated sequences. Here, we report the comparative analysis of Portiera genome sequences both within and between host species. In one whitefly lineage (Bemisia tabaci), we identify large-scale structural polymorphisms in the Portiera genome that exist even within individual insects. This variation is likely mediated by recombination across identical repeats that are maintained by gene conversion. The complete Portiera genome sequence from a distantly related whitefly host (Trialeurodes vaporarium) confirms a history of extensive genome rearrangement in this ancient endosymbiont. Using gene-order-based phylogenetic analysis, we show that the majority of rearrangements have occurred in the B. tabaci lineage, coinciding with an increase in the rate of nucleotide substitutions, a proliferation of short tandem repeats (microsatellites) in intergenic regions, and the loss of many widely conserved genes involved in DNA replication, recombination, and repair. These results indicate that the loss of recombinational machinery is unlikely to be the cause of the extreme structural conservation that is generally observed in obligate endosymbiont genomes and that large, repetitive intergenic regions are an important substrate for genomic rearrangements. PMID:23542079

  12. Review of International Experience with Renewable Energy Obligation Support Mechanisms

    SciTech Connect

    Wiser, R.

    2005-06-01

    The main policy instruments currently used in the EU Member States to achieve the targets set for electricity produced from renewable energy sources are: (1) the quota obligation system; (2) the feed-in tariff system; and (3) the tendering system. The current study aims to review the experience gained with the quota obligation system. The report provides an overview of the regions where obligation systems have been implemented and contains a detailed evaluation of the performance of the obligation systems in the USA, the UK and in Sweden. The obligation systems in these countries have been evaluated based on the following criteria: Effectiveness; Market efficiency; Certainty for the renewable energy industry; Cost effectiveness; Stakeholder support for the obligation system; and Equity. The evaluation of international experiences with the obligation system gives rise to a mixed picture. Although an obligation in theory is effective and cost effective, it seems too early to conclude that the system delivers these promises in practice. On the one hand this is due to the limited period of implementation that makes it hard to distinguish between the direct effect of the system and some teething problems that will be solved in due time. On the other hand, the conclusion can be drawn that the obligation is a complex system, which will only function well if designed carefully. It does seem worthwhile, however, to continue monitoring the experiences with the obligation system abroad, because this will further reveal whether the system is indeed effective and cost effective in practice. In the longer term, e.g. beyond 2010, the introduction of an obligation system in the Netherlands could be considered. Finally, as the design of support schemes is being improved, it appears that the basic concepts of both the obligation system and the feed in system have been refined in such a way that the two systems are gradually converging. An important difference between the two systems however remains, namely that an obligation system relies more on market forces whereas the feed-in system is based on a greater involvement of the government.

  13. Mechanisms of Borrelia burgdorferi internalization and intracellular innate immune signaling

    PubMed Central

    Petnicki-Ocwieja, Tanja; Kern, Aurelie

    2014-01-01

    Lyme disease is a long-term infection whose most severe pathology is characterized by inflammatory arthritis of the lower bearing joints, carditis, and neuropathy. The inflammatory cascades are initiated through the early recognition of invading Borrelia burgdorferi spirochetes by cells of the innate immune response, such as neutrophils and macrophage. B. burgdorferi does not have an intracellular niche and thus much research has focused on immune pathways activated by pathogen recognition molecules at the cell surface, such as the Toll-like receptors (TLRs). However, in recent years, studies have shown that internalization of the bacterium by host cells is an important component of the defense machinery in response to B. burgdorferi. Upon internalization, B. burgdorferi is trafficked through an endo/lysosomal pathway resulting in the activation of a number of intracellular pathogen recognition receptors including TLRs and Nod-like receptors (NLRs). Here we will review the innate immune molecules that participate in both cell surface and intracellular immune activation by B. burgdorferi. PMID:25566512

  14. 5 CFR 2422.34 - Rights and obligations during the pendency of representation proceedings.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...obligations during the pendency of representation proceedings. 2422.34...LABOR RELATIONS AUTHORITY REPRESENTATION PROCEEDINGS § 2422.34...obligations during the pendency of representation proceedings. (a)...

  15. 5 CFR 2422.34 - Rights and obligations during the pendency of representation proceedings.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...obligations during the pendency of representation proceedings. 2422.34...LABOR RELATIONS AUTHORITY REPRESENTATION PROCEEDINGS § 2422.34...obligations during the pendency of representation proceedings. (a)...

  16. 5 CFR 2422.34 - Rights and obligations during the pendency of representation proceedings.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...obligations during the pendency of representation proceedings. 2422.34...LABOR RELATIONS AUTHORITY REPRESENTATION PROCEEDINGS § 2422.34...obligations during the pendency of representation proceedings. (a)...

  17. Molecular basis of host specificity in human pathogenic bacteria

    PubMed Central

    Pan, Xiaolei; Yang, Yang; Zhang, Jing-Ren

    2014-01-01

    Pathogenic bacteria display various levels of host specificity or tropism. While many bacteria can infect a wide range of hosts, certain bacteria have strict host selectivity for humans as obligate human pathogens. Understanding the genetic and molecular basis of host specificity in pathogenic bacteria is important for understanding pathogenic mechanisms, developing better animal models and designing new strategies and therapeutics for the control of microbial diseases. The molecular mechanisms of bacterial host specificity are much less understood than those of viral pathogens, in part due to the complexity of the molecular composition and cellular structure of bacterial cells. However, important progress has been made in identifying and characterizing molecular determinants of bacterial host specificity in the last two decades. It is now clear that the host specificity of bacterial pathogens is determined by multiple molecular interactions between the pathogens and their hosts. Furthermore, certain basic principles regarding the host specificity of bacterial pathogens have emerged from the existing literature. This review focuses on selected human pathogenic bacteria and our current understanding of their host specificity.

  18. The interface between virulence and host response to the pathogenic fungus Histoplasma capsulatum

    Microsoft Academic Search

    Wendy A. Szymczak; George S. Deepe Jr; Michael S. Winters

    2008-01-01

    Intracellular pathogens have evolved machinery to evade the immune response in order to survive within a host. Histoplasma capsulatum, one of the intracellular pathogens, is a dimorphic fungus that dodges innate and adaptive immunity; it escapes immunity\\u000a presumably through virulence factors that permit fungal survival and replication within the host. This review discusses immune\\u000a factors that contribute to the control

  19. Iron in intracellular infection: to provide or to deprive?

    PubMed Central

    Silva-Gomes, Sandro; Vale-Costa, Sílvia; Appelberg, Rui; Gomes, Maria S.

    2013-01-01

    Due to their chemical versatility, transition metals were incorporated as cofactors for several basic metabolic pathways in living organisms. This same characteristic makes them potentially harmful, since they can be engaged in deleterious reactions like Fenton chemistry. As such, organisms have evolved highly specialized mechanisms to supply their own metal needs while keeping their toxic potential in check. This dual character comes into play in host-pathogen interactions, given that the host can either deprive the pathogen of these key nutrients or exploit them to induce toxicity toward the invading agent. Iron stands as the prototypic example of how a metal can be used to limit the growth of pathogens by nutrient deprivation, a mechanism widely studied in Mycobacterium infections. However, the host can also take advantage of iron-induced toxicity to control pathogen proliferation, as observed in infections caused by Leishmania. Whether we may harness either of the two pathways for therapeutical purposes is still ill-defined. In this review, we discuss how modulation of the host iron availability impacts the course of infections, focusing on those caused by two relevant intracellular pathogens, Mycobacterium and Leishmania. PMID:24367768

  20. Professionalism for Medicine: Opportunities and Obligations*

    PubMed Central

    Cruess, Sylvia R; Cruess, Richard L; Johnston, Sharon

    2004-01-01

    Physicians' dual roles-as healer and professional-are linked by codes of ethics governing behaviour and are empowered by science.Being part of a profession entails a societal contract. The profession is granted a monopoly over the use of a body of knowledge and the privilege of self-regulation and, in return, guarantees society professional competence, integrity and the provision of altruistic service.Societal attitudes to professionalism have changed from supportive to increasingly critical-with physicians being criticised for pursuing their own financial interests, and failing to self-regulate in a way that guarantees competence.Professional values are also threatened by many other factors. The most important are the changes in healthcare delivery in the developed world, with control shifting from the profession to the State and/or the corporate sector.For the ideal of professionalism to survive, physicians must understand it and its role in the social contract. They must meet the obligations necessary to sustain professionalism and ensure that healthcare systems support, rather than subvert, behaviour that is compatible with professionalism's values. PMID:15296199

  1. Constraint-based analysis of metabolic capacity of Salmonella typhimurium during host-pathogen interaction

    Microsoft Academic Search

    Anu Raghunathan; Jennifer Reed; Sookil Shin; Bernhard Palsson; Simon Daefler

    2009-01-01

    BACKGROUND: Infections with Salmonella cause significant morbidity and mortality worldwide. Replication of Salmonella typhimurium inside its host cell is a model system for studying the pathogenesis of intracellular bacterial infections. Genome-scale modeling of bacterial metabolic networks provides a powerful tool to identify and analyze pathways required for successful intracellular replication during host-pathogen interaction. RESULTS: We have developed and validated a

  2. Graduate Schools Infection & Immunity and Biology & Medicine

    E-print Network

    Halazonetis, Thanos

    Graduate Schools Infection & Immunity and Biology & Medicine Seminars in Microbiology Monday, 2nd interactions of obligate intracellular pathogens with their hosts, specifically symbiotic protists. His

  3. A Francisella tularensis Pathogenicity Island Required for Intramacrophage Growth

    Microsoft Academic Search

    Francis E. Nano; Na Zhang; Siobhan C. Cowley; Karl E. Klose; Karen K. M. Cheung; Michael J. Roberts; Jagjit S. Ludu; Gregg W. Letendre; Anda I. Meierovics; Gwen Stephens; Karen L. Elkins

    2004-01-01

    Francisella tularensis is a gram-negative, facultative intracellular pathogen that causes the highly infectious zoonotic disease tularemia. We have discovered a ca. 30-kb pathogenicity island of F. tularensis (FPI) that includes four large open reading frames (ORFs) of 2.5 to 3.9 kb and 13 ORFs of 1.5 kb or smaller. Previously, two small genes located near the center of the FPI

  4. 22 CFR 230.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Fiscal Agent obligations. 230.07 Section 230.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...

  5. 22 CFR 230.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...false Fiscal Agent obligations. 230.07 Section 230.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...

  6. 22 CFR 230.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...false Fiscal Agent obligations. 230.07 Section 230.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...

  7. 22 CFR 230.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...false Fiscal Agent obligations. 230.07 Section 230.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...

  8. 22 CFR 230.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...false Fiscal Agent obligations. 230.07 Section 230.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...

  9. 12 CFR 560.42 - State and local government obligations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Indirect payments, such as through a special fund, may qualify as general obligations if a state or political subdivision with taxing authority has unconditionally agreed to provide funds to cover payments. (d) What is appropriate underwriting for...

  10. 12 CFR 160.42 - State and local government obligations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Indirect payments, such as through a special fund, may qualify as general obligations if a state or political subdivision with taxing authority has unconditionally agreed to provide funds to cover payments. (d) For all securities, the...

  11. 12 CFR 160.42 - State and local government obligations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Indirect payments, such as through a special fund, may qualify as general obligations if a state or political subdivision with taxing authority has unconditionally agreed to provide funds to cover payments. (d) For all securities, the...

  12. 7 CFR 760.507 - Obligations of a participant.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...PROGRAMS INDEMNITY PAYMENT PROGRAMS Tree Assistance Program § 760.507 Obligations... (a) Eligible orchardists and nursery tree growers must execute all required documents... (b) Eligible orchardist or nursery tree growers must allow representatives...

  13. 7 CFR 760.507 - Obligations of a participant.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...PROGRAMS INDEMNITY PAYMENT PROGRAMS Tree Assistance Program § 760.507 Obligations... (a) Eligible orchardists and nursery tree growers must execute all required documents... (b) Eligible orchardist or nursery tree growers must allow representatives...

  14. 7 CFR 760.507 - Obligations of a participant.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...PROGRAMS INDEMNITY PAYMENT PROGRAMS Tree Assistance Program § 760.507 Obligations... (a) Eligible orchardists and nursery tree growers must execute all required documents... (b) Eligible orchardist or nursery tree growers must allow representatives...

  15. 7 CFR 783.7 - Obligations of a participant.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...Regulations of the Department of Agriculture (Continued) FARM SERVICE AGENCY, DEPARTMENT OF AGRICULTURE SPECIAL PROGRAMS TREE ASSISTANCE PROGRAM § 783.7 Obligations of a participant. (a) Eligible orchardists must execute all required...

  16. 7 CFR 760.507 - Obligations of a participant.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...PROGRAMS INDEMNITY PAYMENT PROGRAMS Tree Assistance Program § 760.507 Obligations... (a) Eligible orchardists and nursery tree growers must execute all required documents... (b) Eligible orchardist or nursery tree growers must allow representatives...

  17. 7 CFR 1416.705 - Obligations of a participant.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS 2006 EMERGENCY AGRICULTURAL DISASTER ASSISTANCE PROGRAMS 2005 Hurricane Tree Assistance Program § 1416.705 Obligations of a participant. (a) Eligible producers must execute all required...

  18. 38 CFR 17.633 - Deferment of obligated service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...17.633 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS MEDICAL Visual Impairment and Orientation and Mobility Professional Scholarship Program § 17.633 Deferment of obligated service. Deferment of...

  19. 32 CFR 220.9 - Rights and obligations of beneficiaries.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...party payer's plan. Such beneficiaries are also required to provide...might be applicable, a beneficiary has an obligation to provide...and this part, including identification of policy numbers, claim...2) Uniformed Services beneficiaries are required to...

  20. 48 CFR 243.204-70-4 - Limitations on obligations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE CONTRACT MANAGEMENT CONTRACT MODIFICATIONS Change Orders 243.204-70-4 Limitations on obligations. (a) The Government shall not...

  1. 48 CFR 243.204-70-4 - Limitations on obligations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT OF DEFENSE CONTRACT MANAGEMENT CONTRACT MODIFICATIONS Change Orders 243.204-70-4 Limitations on obligations. (a) The Government shall not...

  2. 7 CFR 930.163 - Deferment of restricted obligation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW YORK, PENNSYLVANIA, OREGON, UTAH, WASHINGTON, AND WISCONSIN Administrative Rules and Regulations § 930.163 Deferment of restricted obligation. A handler...

  3. 18 CFR 367.2300 - Account 230, Asset retirement obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...SUBJECT TO THE PROVISIONS OF THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT Balance Sheet Chart of Accounts Other Noncurrent Liabilities § 367.2300 Account 230, Asset retirement obligations....

  4. 22 CFR 231.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Agent obligations. 231.07 Section 231.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ARAB REPUBLIC OF EGYPT LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUBLIC LAW...

  5. 22 CFR 231.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Agent obligations. 231.07 Section 231.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ARAB REPUBLIC OF EGYPT LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUBLIC LAW...

  6. 22 CFR 231.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Agent obligations. 231.07 Section 231.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ARAB REPUBLIC OF EGYPT LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUBLIC LAW...

  7. 22 CFR 231.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Agent obligations. 231.07 Section 231.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ARAB REPUBLIC OF EGYPT LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUBLIC LAW...

  8. 22 CFR 231.07 - Fiscal Agent obligations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Agent obligations. 231.07 Section 231.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT ARAB REPUBLIC OF EGYPT LOAN GUARANTEES ISSUED UNDER THE EMERGENCY WARTIME SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUBLIC LAW...

  9. 31 CFR 223.18 - Performance of agency obligations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE SURETY COMPANIES DOING BUSINESS WITH THE UNITED STATES § 223.18 Performance of agency obligations. (a)...

  10. 31 CFR 223.18 - Performance of agency obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE SURETY COMPANIES DOING BUSINESS WITH THE UNITED STATES § 223.18 Performance of agency obligations. (a)...

  11. 31 CFR 223.18 - Performance of agency obligations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE SURETY COMPANIES DOING BUSINESS WITH THE UNITED STATES § 223.18 Performance of agency obligations. (a)...

  12. 31 CFR 223.18 - Performance of agency obligations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE SURETY COMPANIES DOING BUSINESS WITH THE UNITED STATES § 223.18 Performance of agency obligations. (a)...

  13. 32 CFR 220.9 - Rights and obligations of beneficiaries.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.9 Rights and obligations...be required. (b) Availability of healthcare services unaffected. The availability of healthcare services in any facility of the...

  14. 32 CFR 220.9 - Rights and obligations of beneficiaries.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.9 Rights and obligations...be required. (b) Availability of healthcare services unaffected. The availability of healthcare services in any facility of the...

  15. 32 CFR 220.9 - Rights and obligations of beneficiaries.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.9 Rights and obligations...be required. (b) Availability of healthcare services unaffected. The availability of healthcare services in any facility of the...

  16. 32 CFR 220.9 - Rights and obligations of beneficiaries.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.9 Rights and obligations...be required. (b) Availability of healthcare services unaffected. The availability of healthcare services in any facility of the...

  17. Intracellular bacteriolysis triggers a massive apoptotic cell death in Shigella-infected epithelial cells

    Microsoft Academic Search

    Ivan Tattoli; Luigi Lembo-Fazio; Giulia Nigro; Leticia A. M. Carneiro; Elisabetta Ferraro; Giacomo Rossi; Maria Celeste Martino; Maria Egle de Stefano; Francesco Cecconi; Stephen E. Girardin; Dana J. Philpott; Maria Lina Bernardini

    2008-01-01

    Infected epithelial cells, which act as a first barrier against pathogens, seldom undergo apoptosis. Rather, infected epithelial cells undergo a slow cell death that displays hallmarks of necrosis. Here, we demonstrate that rapid intracellular lysis of Shigella flexneri, provoked by either the use of a diaminopimelic acid auxotroph mutant or treatment of infected cells with antibiotics of the ?-lactam family,

  18. Immunological mechanisms contributing to the double burden of diabetes and intracellular bacterial infections.

    PubMed

    Hodgson, Kelly; Morris, Jodie; Bridson, Tahnee; Govan, Brenda; Rush, Catherine; Ketheesan, Natkunam

    2015-02-01

    Diabetes has been recognized as an important risk factor for a variety of intracellular bacterial infections, but research into the dysregulated immune mechanisms contributing to the impaired host-pathogen interactions is in its infancy. Diabetes is characterized by a chronic state of low-grade inflammation due to activation of pro-inflammatory mediators and increased formation of advanced glycation end products. Increased oxidative stress also exacerbates the chronic inflammatory processes observed in diabetes. The reduced phagocytic and antibacterial activity of neutrophils and macrophages provides an intracellular niche for the pathogen to replicate. Phagocytic and antibacterial dysfunction may be mediated directly through altered glucose metabolism and oxidative stress. Furthermore, impaired activation of natural killer cells contributes to decreased levels of interferon-?, required for promoting macrophage antibacterial mechanisms. Together with impaired dendritic cell function, this impedes timely activation of adaptive immune responses. Increased intracellular oxidation of antigen-presenting cells in individuals with diabetes alters the cytokine profile generated and the subsequent balance of T-cell immunity. The establishment of acute intracellular bacterial infections in the diabetic host is associated with impaired T-cell-mediated immune responses. Concomitant to the greater intracellular bacterial burden and potential cumulative effect of chronic inflammatory processes, late hyper-inflammatory cytokine responses are often observed in individuals with diabetes, contributing to systemic pathology. The convergence of intracellular bacterial infections and diabetes poses new challenges for immunologists, providing the impetus for multidisciplinary research. PMID:25262977

  19. Nitric oxide detoxification by Fusarium verticillioides flavohemoglobin and role in pathogenicity of maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium verticillioides is a non-obligate plant pathogen of maize causing a number of specific diseases, including root rot, kernel rot, seed rot, stalk rot, and seedling blight. The saprophytic nature of this fungus, its production of the mycotoxin fumonisin, and complex relationship maize puts t...

  20. Employer obligations versus fulfillment and the effects on organizational citizenship and innovative work

    Microsoft Academic Search

    Sandra K. Newton; Linda I. Nowak

    This research investigated the relationship among discrepancies between the employers' obligations and the level of fulfillment of those obligations and the information technology (IT) professionals' citizenship and innovative work behaviors. The dimensional approach to the psychological contract was used to demonstrate the IT professional's perceptions of their employer's obligations and the level of fulfillment of those obligations. Survey data from

  1. A Longitudinal Study of Family Obligation and Depressive Symptoms Among Chinese American Adolescents

    Microsoft Academic Search

    Linda P. Juang; Jeffrey T. Cookston

    2009-01-01

    The purpose of this 2-year, 3-wave longitudinal study of Chinese American adolescents was to examine how family obligation behaviors and attitudes change over time; how gender, nativity, and birth order predict these trajectories; and whether family obligation relates to depressive symptoms. Findings suggest that family obligation behaviors decreased over the 2-year period but that family obligation attitudes were stable. Moreover,

  2. Temperature dependent virulence of obligate and facultative fungal pathogens of honeybee brood

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chalkbrood (Ascosphaera apis) and stonebrood (Aspergillus flavus) are well known fungal brood diseases of honeybees (Apis mellifera), but they have hardly been systematically studied because the difficulty of rearing larvae in vitro has precluded controlled experimentation. Chalkbrood is a chronic h...

  3. Brucella microti: the genome sequence of an emerging pathogen

    Microsoft Academic Search

    Stéphane Audic; Magali Lescot; Jean-Michel Claverie; Holger C Scholz

    2009-01-01

    BACKGROUND: Using a combination of pyrosequencing and conventional Sanger sequencing, the complete genome sequence of the recently described novel Brucella species, Brucella microti, was determined. B. microti is a member of the genus Brucella within the Alphaproteobacteria, which consists of medically important highly pathogenic facultative intracellular bacteria. In contrast to all other Brucella species, B. microti is a fast growing

  4. Draft Genome Sequence of the Fish Pathogen Piscirickettsia salmonis

    PubMed Central

    Eppinger, Mark; McNair, Katelyn; Zogaj, Xhavit; Dinsdale, Elizabeth A.; Edwards, Robert A.

    2013-01-01

    Piscirickettsia salmonis is a Gram-negative intracellular fish pathogen that has a significant impact on the salmon industry. Here, we report the genome sequence of P. salmonis strain LF-89. This is the first draft genome sequence of P. salmonis, and it reveals interesting attributes, including flagellar genes, despite this bacterium being considered nonmotile. PMID:24201203

  5. The destructive citrus pathogen, ‘Candidatus Liberibacter asiaticus’ encodes a functional flagellin characteristic of a pathogen-associated molecular pattern

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is presently the most devastating citrus disease worldwide. As an intracellular plant pathogen and insect symbiont, the HLB bacterium, ‘Candidatus Liberibacter asiaticus’ (Las) retains the entire flagellum-encoding gene cluster in its significantly reduced genome. Las encodes a...

  6. Intracellular calcium channels in protozoa.

    PubMed

    Docampo, Roberto; Moreno, Silvia N J; Plattner, Helmut

    2014-09-15

    Ca(2+)-signaling pathways and intracellular Ca(2+) channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other intracellular channels predates the divergence of animals and fungi as evidenced by their presence in the choanoflagellate Monosiga brevicollis, the closest known relative to metazoans. The first protozoan IP3R cloned, from the ciliate Paramecium, displays strong sequence similarity to the rat type 3 IP3R. This ciliate has a large number of IP3- and ryanodine(Ry)-like receptors in six subfamilies suggesting the evolutionary adaptation to local requirements for an expanding diversification of vesicle trafficking. IP3Rs have also been functionally characterized in trypanosomatids, where they are essential for growth, differentiation, and establishment of infection. The presence of the mitochondrial calcium uniporter (MCU) in a number of protozoa indicates that mitochondrial regulation of Ca(2+) signaling is also an early appearance in evolution, and contributed to the discovery of the molecular nature of this channel in mammalian cells. There is only sequence evidence for the occurrence of two-pore channels (TPCs), transient receptor potential Ca(2+) channels (TRPCs) and intracellular mechanosensitive Ca(2+)-channels in Paramecium and in parasitic protozoa. PMID:24291099

  7. Stochastic models of intracellular transport

    NASA Astrophysics Data System (ADS)

    Bressloff, Paul C.; Newby, Jay M.

    2013-01-01

    The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures.

  8. Pathogens Hijack the Epigenome

    PubMed Central

    Silmon de Monerri, Natalie C.; Kim, Kami

    2015-01-01

    Pathogens have evolved strategies to promote their survival by dramatically modifying the transcriptional profile and protein content of the host cells they infect. Modifications of the host transcriptome and proteome are mediated by pathogen-encoded effector molecules that modulate host cells through a variety of different mechanisms. Recent studies highlight the importance of the host chromatin and other epigenetic regulators as targets of pathogens. Host gene regulatory mechanisms may be targeted through cytoplasmic signaling, directly by pathogen effector proteins, and possibly by pathogen RNA. Although many of these changes are short-lived and persist only during the course of infection, several studies indicate that pathogens are able to induce long-term, heritable changes that are essential to pathogenesis of infectious diseases and persistence of pathogens within their hosts. In this review, we discuss how pathogens modulate the epigenome of host cells, a new and flourishing avenue of host-pathogen interaction studies. PMID:24525150

  9. Intracellular methicillin selection of Listeria monocytogenes mutants unable to replicate in a macrophage cell line.

    PubMed Central

    Camilli, A; Paynton, C R; Portnoy, D A

    1989-01-01

    To dissect the determinants of Listeria monocytogenes that are required for pathogenicity, we designed an intracellular selection protocol based on penicillin selection to isolate mutants defective for intracellular growth. Eight independent mutants obtained by insertion of Tn916 were isolated that were resistant to methicillin treatment following internalization by the J774 macrophage-like cell line. Seven mutants were absolutely defective for intracellular growth, whereas one showed abortive intracellular growth. The majority of the mutants were nonhemolytic and lacked a secreted 58-kDa polypeptide thought to be the L. monocytogenes hemolysin, listeriolysin O. Southern blot analysis indicated that one mutant contained a Tn916 insertion in hlyA, the listeriolysin O structural gene, which resulted in a truncated listeriolysin O polypeptide, whereas another mutant contained an insertion immediately upstream of hlyA, which resulted in reduced expression of listeriolysin O. The other mutants contained Tn916 insertions in genes other than hlyA, although all but one were nonhemolytic. Revertants isolated by their ability to grow within tissue culture cells regained hemolytic activity. These data show that intracellular methicillin selection facilitates isolation of mutations in genes required for intracellular growth and strengthens the premise that listeriolysin O is essential for intracellular growth. Images PMID:2501788

  10. What are the public obligations to AIDS patients?

    PubMed

    Kelley, David

    2002-01-01

    The operating assumption in most discussions of health policy is that government has some responsibility for the health of its citizens and that it may legitimately tax, subsidize, and regulate its citizens in the exercise of that responsibility. On this assumption, public obligations to HIV/AIDS patients are a function of their needs in relationship to other health needs. This paper challenges the operating assumption by arguing that it cannot be grounded in the obligations that individuals have to each other. The paper rests on its own assumption: the moral theory of individualism. On this theory, individuals are ends in themselves who have the right to choose their own actions and uses of their resources; they do not have unchosen obligations to help others. In regard to HIV/AIDS patients, consequently, individuals have no duty to help, nor any other obligation beyond that of respecting their rights; and there is no valid basis for government regulations or subsidies on their behalf. The paper argues against the two approaches commonly used to defend a more expansive view of individual obligations and the role of government. The first is the assumption of welfare rights to goods and services; the second is the assumption that distributive justice requires some redistribution of health care resources. PMID:15971567

  11. Intracellular trafficking of nonviral vectors

    Microsoft Academic Search

    L K Medina-Kauwe; J Xie; S Hamm-Alvarez

    2005-01-01

    Nonviral vectors continue to be attractive alternatives to viruses due to their low toxicity and immunogenicity, lack of pathogenicity, and ease of pharmacologic production. However, nonviral vectors also continue to suffer from relatively low levels of gene transfer compared to viruses, thus the drive to improve these vectors continues. Many studies on vector–cell interactions have reported that nonviral vectors bind

  12. Effector-triggered defence against apoplastic fungal pathogens

    PubMed Central

    Stotz, Henrik U.; Mitrousia, Georgia K.; de Wit, Pierre J.G.M.; Fitt, Bruce D.L.

    2014-01-01

    R gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed ‘effector-triggered defence’ (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of crops. PMID:24856287

  13. Tick vaccines and the control of tick-borne pathogens

    PubMed Central

    Merino, Octavio; Alberdi, Pilar; Pérez de la Lastra, José M.; de la Fuente, José

    2013-01-01

    Ticks are obligate hematophagous ectoparasites that transmit a wide variety of pathogens to humans and animals. The incidence of tick-borne diseases has increased worldwide in both humans and domestic animals over the past years resulting in greater interest in the study of tick-host-pathogen interactions. Advances in vector and pathogen genomics and proteomics have moved forward our knowledge of the vector-pathogen interactions that take place during the colonization and transmission of arthropod-borne microbes. Tick-borne pathogens adapt from the vector to the mammalian host by differential gene expression thus modulating host processes. In recent years, studies have shown that targeting tick proteins by vaccination can not only reduce tick feeding and reproduction, but also the infection and transmission of pathogens from the tick to the vertebrate host. In this article, we review the tick-protective antigens that have been identified for the formulation of tick vaccines and the effect of these vaccines on the control of tick-borne pathogens. PMID:23847771

  14. Pathogen life-history trade-offs revealed in allopatry.

    PubMed

    Susi, Hanna; Laine, Anna-Liisa

    2013-11-01

    Trade-offs in life-history traits is a central tenet in evolutionary biology, yet their ubiquity and relevance to realized fitness in natural populations remains questioned. Trade-offs in pathogens are of particular interest because they may constrain the evolution and epidemiology of diseases. Here, we studied life-history traits determining transmission in the obligate fungal pathogen, Podosphaera plantaginis, infecting Plantago lanceolata. We find that although traits are positively associated on sympatric host genotypes, on allopatric host genotypes relationships between infectivity and subsequent transmission traits change shape, becoming even negative. The epidemiological prediction of this change in life-history relationships in allopatry is lower disease prevalence in newly established pathogen populations. An analysis of the natural pathogen metapopulation confirms that disease prevalence is lower in newly established pathogen populations and they are more prone to go extinct during winter than older pathogen populations. Hence, life-history trade-offs mediated by pathogen local adaptation may influence epidemiological dynamics at both population and metapopulation levels. PMID:24152013

  15. PATHOGENS: VIEWS OF EPA'S PATHOGEN EQUIVALENCY COMMITTEE

    EPA Science Inventory

    This presentation reviews the pathogenic microorganisms that may be found in municipal sewage sludge and the commonly employed Class A and B processes for controlling pathogens. It notes how extensively they are used and discusses issues and concerns with their application. Pre...

  16. Endosymbiosis In Statu Nascendi: Close Phylogenetic RelationshipBetween Obligately Endosymbiotic and Obligately Free-LivingPolynucleobacter Strains (Betaproteobacteria)

    SciTech Connect

    Vannini, Claudia; Pockl, Matthias; Petroni, Giulio; Wu, Qinglong; Lang, Elke; Stackebrandt, Erko; Schrallhammer, Martina; Richardson, PaulM.; Hahn, Martin W.

    2006-07-21

    Bacterial strains affiliated to the phylogenetically shallowsubcluster C (PnecC) of the 28 Polynucleobacter cluster, which ischaracterized by a minimal 16S rRNA gene sequence similarity of approx.98.5 percent, have been reported to occur as obligate endosymbionts of 30ciliates (Euplotes spp.), as well as to occur as free-living cells in thepelagic zone of freshwater habitats. We investigated if these two groupsof closely related bacteria represent 32 strains fundamentally differingin lifestyle, or if they simply represent different stages of afacultative endosymbiotic lifestyle. The phylogenetic analysis of 16SrRNA gene and 16S34 23S ITS sequences of five endosymbiont strains fromtwo different Euplotes species and 40 pure culture strains demonstratedhost-species-specific clustering of the endosymbiont 36 sequences withinthe PnecC subcluster. The sequences of the endosymbionts showedcharacteristics indicating an obligate endosymbiotic lifestyle.Cultivation experiments 38 revealed fundamental differences inphysiological adaptations, and determination of the genome sizesindicated a slight size reduction in endosymbiotic strains. We concludethat the 40 two groups of PnecC bacteria represent obligately free-livingand obligately endosymbiotic strains, respectively, and do not representdifferent stages of the same complex lifecycle. 42 These closely relatedstrains occupy completely separated ecological niches. To our bestknowledge, this is the closest phylogenetic relationship between obligateendosymbionts and 44 obligately free-living bacteria everrevealed.

  17. Francisella tularensis Harvests Nutrients Derived via ATG5-Independent Autophagy to Support Intracellular Growth

    PubMed Central

    Ziehr, Benjamin; Taft-Benz, Sharon; Moorman, Nathaniel; Kawula, Thomas

    2013-01-01

    Francisella tularensis is a highly virulent intracellular pathogen that invades and replicates within numerous host cell types including macrophages, hepatocytes and pneumocytes. By 24 hours post invasion, F. tularensis replicates up to 1000-fold in the cytoplasm of infected cells. To achieve such rapid intracellular proliferation, F. tularensis must scavenge large quantities of essential carbon and energy sources from the host cell while evading anti-microbial immune responses. We found that macroautophagy, a eukaryotic cell process that primarily degrades host cell proteins and organelles as well as intracellular pathogens, was induced in F. tularensis infected cells. F. tularensis not only survived macroautophagy, but optimal intracellular bacterial growth was found to require macroautophagy. Intracellular growth upon macroautophagy inhibition was rescued by supplying excess nonessential amino acids or pyruvate, demonstrating that autophagy derived nutrients provide carbon and energy sources that support F. tularensis proliferation. Furthermore, F. tularensis did not require canonical, ATG5-dependent autophagy pathway induction but instead induced an ATG5-independent autophagy pathway. ATG5-independent autophagy induction caused the degradation of cellular constituents resulting in the release of nutrients that the bacteria harvested to support bacterial replication. Canonical macroautophagy limits the growth of several different bacterial species. However, our data demonstrate that ATG5-independent macroautophagy may be beneficial to some cytoplasmic bacteria by supplying nutrients to support bacterial growth. PMID:23966861

  18. Barcoding Hedgehog for Intracellular Transport

    NSDL National Science Digital Library

    Thomas B. Kornberg (San Francisco; University of California REV)

    2011-11-22

    Hedgehog, an essential protein for the development of many vertebrate and invertebrate organs, signals at both short and long distances to control growth and patterning. The mechanism by which it moves between source and target cells is not known, but characterization of the covalent modification of its N terminus with palmitate and of its C terminus with cholesterol has led to the suggestion that the lipophilic properties of the modified protein serve to regulate movement after its secretion into the extracellular space. Another interpretation and model is that the C-terminal cholesterol acts to target Hedgehog to an intracellular trafficking pathway that prepares Hedgehog for release in an encapsulated form.

  19. The intracellular galactoglycome in Trichoderma reesei during growth on lactose.

    PubMed

    Karaffa, Levente; Coulier, Leon; Fekete, Erzsébet; Overkamp, Karin M; Druzhinina, Irina S; Mikus, Marianna; Seiboth, Bernhard; Novák, Levente; Punt, Peter J; Kubicek, Christian P

    2013-06-01

    Lactose (1,4-0-?-D-galactopyranosyl-D-glucose) is used as a soluble carbon source for the production of cellulases and hemicellulases for-among other purposes-use in biofuel and biorefinery industries. The mechanism how lactose induces cellulase formation in T. reesei is enigmatic, however. Previous results from our laboratory raised the hypothesis that intermediates from the two galactose catabolic pathway may give rise to the accumulation of intracellular oligogalactosides that could act as inducer. Here we have therefore used high-performance anion-exchange chromatography-mass spectrometry to study the intracellular galactoglycome of T. reesei during growth on lactose, in T. reesei mutants impaired in galactose catabolism, and in strains with different cellulase productivities. Lactose, allo-lactose, and lactulose were detected in the highest amounts in all strains, and two trisaccharides (Gal-?-1,6-Gal-?-1,4-Glc/Fru and Gal-?-1,4-Gal-?-1,4-Glc/Fru) also accumulated to significant levels. Glucose and galactose, as well as four further oligosaccharides (Gal-?-1,3/1,4/1,6-Gal; Gal-?-1,2-Glc) were only detected in minor amounts. In addition, one unknown disaccharide (Hex-?-1,1-Hex) and four trisaccharides were also detected. The accumulation of the unknown hexose disaccharide was shown to correlate with cellulase formation in the improved mutant strains as well as the galactose pathway mutants, and Gal-?-1,4-Gal-?-1,4-Glc/Fru and two other unknown hexose trisaccharides correlated with cellulase production only in the pathway mutants, suggesting that these compounds could be involved in cellulase induction by lactose. The nature of these oligosaccharides, however, suggests their formation by transglycosylation rather than by glycosyltransferases. Based on our results, the obligate nature of both galactose catabolic pathways for this induction must have another biochemical basis than providing substrates for inducer formation. PMID:23299458

  20. Settling Down: The Genome of Serratia symbiotica from the Aphid Cinara tujafilina Zooms in on the Process of Accommodation to a Cooperative Intracellular Life

    PubMed Central

    Manzano-Marín, Alejandro; Latorre, Amparo

    2014-01-01

    Particularly interesting cases of mutualistic endosymbioses come from the establishment of co-obligate associations of more than one species of endosymbiotic bacteria. Throughout symbiotic accommodation from a free-living bacterium, passing through a facultative stage and ending as an obligate intracellular one, the symbiont experiences massive genomic losses and phenotypic adjustments. Here, we scrutinized the changes in the coevolution of Serratia symbiotica and Buchnera aphidicola endosymbionts in aphids, paying particular attention to the transformations undergone by S. symbiotica to become an obligate endosymbiont. Although it is already known that S. symbiotica is facultative in Acyrthosiphon pisum, in Cinara cedri it has established a co-obligate endosymbiotic consortium along with B. aphidicola to fulfill the aphid’s nutritional requirements. The state of this association in C. tujafilina, an aphid belonging to the same subfamily (Lachninae) that C. cedri, remained unknown. Here, we report the genome of S. symbiotica strain SCt-VLC from the aphid C. tujafilina. While being phylogenetically and genomically very closely related to the facultative endosymbiont S. symbiotica from the aphid A. pisum, it shows a variety of metabolic, genetic, and architectural features, which point toward this endosymbiont being one step closer to an obligate intracellular one. We also describe in depth the process of genome rearrangements suffered by S. symbiotica and the role mobile elements play in gene inactivations. Finally, we postulate the supply to the host of the essential riboflavin (vitamin B2) as key to the establishment of S. symbiotica as a co-obligate endosymbiont in the aphids belonging to the subfamily Lachninane. PMID:24951564

  1. Settling down: the genome of Serratia symbiotica from the aphid Cinara tujafilina zooms in on the process of accommodation to a cooperative intracellular life.

    PubMed

    Manzano-Marín, Alejandro; Latorre, Amparo

    2014-07-01

    Particularly interesting cases of mutualistic endosymbioses come from the establishment of co-obligate associations of more than one species of endosymbiotic bacteria. Throughout symbiotic accommodation from a free-living bacterium, passing through a facultative stage and ending as an obligate intracellular one, the symbiont experiences massive genomic losses and phenotypic adjustments. Here, we scrutinized the changes in the coevolution of Serratia symbiotica and Buchnera aphidicola endosymbionts in aphids, paying particular attention to the transformations undergone by S. symbiotica to become an obligate endosymbiont. Although it is already known that S. symbiotica is facultative in Acyrthosiphon pisum, in Cinara cedri it has established a co-obligate endosymbiotic consortium along with B. aphidicola to fulfill the aphid's nutritional requirements. The state of this association in C. tujafilina, an aphid belonging to the same subfamily (Lachninae) that C. cedri, remained unknown. Here, we report the genome of S. symbiotica strain SCt-VLC from the aphid C. tujafilina. While being phylogenetically and genomically very closely related to the facultative endosymbiont S. symbiotica from the aphid A. pisum, it shows a variety of metabolic, genetic, and architectural features, which point toward this endosymbiont being one step closer to an obligate intracellular one. We also describe in depth the process of genome rearrangements suffered by S. symbiotica and the role mobile elements play in gene inactivations. Finally, we postulate the supply to the host of the essential riboflavin (vitamin B2) as key to the establishment of S. symbiotica as a co-obligate endosymbiont in the aphids belonging to the subfamily Lachninane. PMID:24951564

  2. Clinical review: Influenza pandemic – physicians and their obligations

    Microsoft Academic Search

    Devanand Anantham; Wendy McHugh; Stephen O'Neill; Lachlan Forrow

    2008-01-01

    An influenza pandemic threatens to be the most lethal public health crisis to confront the world. Physicians will have critical roles in diagnosis, containment and treatment of influenza, and their commitment to treat despite increased personal risks is essential for a successful public health response. The obligations of the medical profession stem from the unique skills of its practitioners, who

  3. 34 CFR 75.707 - When obligations are made.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    34 ? Education ? 1 ? 2013-07-01 ? 2013-07-01 ? false ? When obligations are made. ? 75.707 ? Section 75.707 ? Education ? Office of the Secretary, Department of Education ? DIRECT GRANT PROGRAMS ? What Are the Administrative Responsibilities of a Grantee? ? General Administrative Responsibilities...

  4. Oxidation of Inorganic Sulfur Compounds by Obligately Organotrophic Bacteria

    Microsoft Academic Search

    D. Yu. Sorokin

    2003-01-01

    New data obtained by the author and other researchers on two different groups of obligately heterotrophic bacteria capable of inorganic sulfur oxidation are reviewed. Among culturable marine and (halo)alkaliphilic heterotrophs oxidizing sulfur compounds (thiosulfate and, much less actively, elemental sulfur and sulfide) incompletely to tetrathionate, representatives of the gammaproteobacteria, especially from the Halomonas group, dominate. Some denitrifying species from this

  5. Who can be morally obligated to be a vegetarian?

    Microsoft Academic Search

    Evelyn Pluhar

    1992-01-01

    Kathryn Paxton George has recently argued that vegetarianism cannot be a moral obligation for most human beings, even if Tom Regan is correct in arguing that humans and certain nonhuman animals are equally inherently valuable. She holds that Regan's liberty principle permits humans to kill and eat innocent others who have a right to life, provided that doing so prevents

  6. European air transport public service obligations: a periodic review

    Microsoft Academic Search

    Aisling Reynolds-Feighan

    1995-01-01

    The ‘Third Package’ of European Union air transport liberalisation measures came into effect on 1 January 1993 and has substantially reduced the restrictions on interstate flight operations. The package of measures also includes provision for the member states to impose ‘public service obligations’ on low-density routes which were deemed necessary for the purposes of regional development. In this paper, it

  7. Classification Revisions Reduce Reported Federal Development Obligations. InfoBrief.

    ERIC Educational Resources Information Center

    Jankowski, John E.

    This document reports on federal Research and Development (R&D) funding trends for the last 10 years and explains the sources of Federal R&D revisions. The data are obtained from an annual census of approximately 30 federal agencies that report obligation data to the National Science Foundation Survey of Federal Funds for R&D. (YDS)

  8. Are YA Novelists Morally Obligated To Offer Their Readers Hope?

    ERIC Educational Resources Information Center

    Ritter, John H.

    2003-01-01

    Presents a letter from a sixth-grade student to the author and presents his response letter which are found in a compilation of author/reader correspondence called "Letters of Hope." Discusses the role of the storyteller and considers if writers of young adult literature feel an obligation to provide hope for their readers. (SG)

  9. A test for obligate apomixis in grain sorghum R473

    Microsoft Academic Search

    D. R. Marshall; R. W. Downes

    1977-01-01

    Segregation patterns in progeny arrays of selfed plants, heterozygous for the Mdh 1 isozyme marker locus, were used in an attempt to confirm the presence of apomixis in the grain sorghum line R473. No evidence for obligate apomictic reproduction was obtained. However, our studies did not rule out the possibility of a low level of facultative apomixis in R473.

  10. Asset retirement obligations: a reporting concern for healthcare facilities.

    PubMed

    Berg, Gary G; Bayes, Paul E; Morgan, Robert G

    2008-11-01

    FASB statements and SEC guidelines give direction as to how healthcare organizations should account for their asset retirement obligations (AROs) where environmental issues are concerned. A key consideration is that current costs associated with environmental problems, such as encapsulating asbestos, are to be accounted for as part of an asset's cost and depreciated over the asset's remaining life. PMID:18990844

  11. Revisional metabolic/bariatric surgery: a moral obligation.

    PubMed

    Buchwald, Henry

    2015-03-01

    Revisional metabolic/bariatric surgery is a moral obligation; for not to perform revisional surgery is a denial of the precepts of our discipline and an abandonment of the underprivileged population who has placed its trust and future in our hands. PMID:25344464

  12. Obama states obligation to act on climate change

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-11-01

    Obama states obligation to act on climate change Noting increased global temperatures, Arctic ice melt, and severe weather events, President Barack Obama said that climate change is real and called for a conversation across the country to determine what can be done about it.

  13. Civic Engagement in Teacher Education: Activities or Obligation?

    ERIC Educational Resources Information Center

    Erickson, Lynnette B.

    2011-01-01

    Some might question whether teacher education programs have an obligation to promote or enhance the teaching of civic responsibility and engagement, especially if they believe that the primary purpose of education is to prepare students to enter the workforce or be successful as individuals. However, others have a more encompassing view of…

  14. Eradication of intracellular Francisella tularensis in THP-1 human macrophages with a novel autophagy inducing agent

    PubMed Central

    2009-01-01

    Background Autophagy has been shown recently to play an important role in the intracellular survival of several pathogenic bacteria. In this study, we investigated the effect of a novel small-molecule autophagy-inducing agent, AR-12, on the survival of Francisella tularensis, the causative bacterium of tularemia in humans and a potential bioterrorism agent, in macrophages. Methods and results Our results show that AR-12 induces autophagy in THP-1 macrophages, as indicated by increased autophagosome formation, and potently inhibits the intracellular survival of F. tularensis (type A strain, Schu S4) and F. novicida in macrophages in association with increased bacterial co-localization with autophagosomes. The effect of AR-12 on intracellular F. novicida was fully reversed in the presence of the autophagy inhibitor, 3-methyl adenine or the lysosome inhibitor, chloroquine. Intracellular F. novicida were not susceptible to the inhibitory activity of AR-12 added at 12 h post-infection in THP-1 macrophages, and this lack of susceptibility was independent of the intracellular location of bacteria. Conclusion Together, AR-12 represents a proof-of-principle that intracellular F. tularensis can be eradicated by small-molecule agents that target innate immunity. PMID:20003180

  15. 31 CFR 225.3 - Pledge of Government obligations in lieu of a bond with surety or sureties.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Pledge of Government obligations in lieu of a bond with... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.3 Pledge of Government obligations in lieu of a bond...

  16. 31 CFR 225.3 - Pledge of Government obligations in lieu of a bond with surety or sureties.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Pledge of Government obligations in lieu of a bond with... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.3 Pledge of Government obligations in lieu of a bond...

  17. 31 CFR 225.3 - Pledge of Government obligations in lieu of a bond with surety or sureties.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Pledge of Government obligations in lieu of a bond with... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.3 Pledge of Government obligations in lieu of a bond...

  18. 31 CFR 225.3 - Pledge of Government obligations in lieu of a bond with surety or sureties.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Pledge of Government obligations in lieu of a bond with... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.3 Pledge of Government obligations in lieu of a bond...

  19. 31 CFR 225.3 - Pledge of Government obligations in lieu of a bond with surety or sureties.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Pledge of Government obligations in lieu of a bond with... ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.3 Pledge of Government obligations in lieu of a bond...

  20. 24 CFR 811.110 - Refunding of obligations issued to finance Section 8 projects.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Refunding of obligations issued to finance Section 8 projects. 811.110 Section...110 Refunding of obligations issued to finance Section 8 projects. (a) This...savings and, if necessary, HUD will finance in refunding bond debt service...

  1. 40 CFR 80.1407 - How are the Renewable Volume Obligations calculated?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...following formulas: (1) Cellulosic biofuel. RVOCB,i = (RFStdCB,i ...Renewable Volume Obligation for cellulosic biofuel for an obligated party for calendar year...RFStdCB,i = The standard for cellulosic biofuel for calendar year i, determined by...

  2. 40 CFR 80.1407 - How are the Renewable Volume Obligations calculated?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...following formulas: (1) Cellulosic biofuel. RVOCB,i = (RFStdCB,i ...Renewable Volume Obligation for cellulosic biofuel for an obligated party for calendar year...RFStdCB,i = The standard for cellulosic biofuel for calendar year i, determined by...

  3. 40 CFR 80.1407 - How are the Renewable Volume Obligations calculated?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...following formulas: (1) Cellulosic biofuel. RVOCB,i = (RFStdCB,i ...Renewable Volume Obligation for cellulosic biofuel for an obligated party for calendar year...RFStdCB,i = The standard for cellulosic biofuel for calendar year i, determined by...

  4. 40 CFR 80.1407 - How are the Renewable Volume Obligations calculated?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...following formulas: (1) Cellulosic biofuel. RVOCB,i = (RFStdCB,i ...Renewable Volume Obligation for cellulosic biofuel for an obligated party for calendar year...RFStdCB,i = The standard for cellulosic biofuel for calendar year i, determined by...

  5. 40 CFR 80.1407 - How are the Renewable Volume Obligations calculated?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...following formulas: (1) Cellulosic biofuel. RVOCB,i = (RFStdCB,i ...Renewable Volume Obligation for cellulosic biofuel for an obligated party for calendar year...RFStdCB,i = The standard for cellulosic biofuel for calendar year i, determined by...

  6. 31 CFR 1010.940 - Photographic or other reproductions of Government obligations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Photographic or other reproductions of Government obligations. 1010...1010.940 Photographic or other reproductions of Government obligations. Nothing...authorize the microfilming or other reproduction of: (a) Currency or other...

  7. 31 CFR 103.52 - Photographic or other reproductions of Government obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Photographic or other reproductions of Government obligations. 103... § 103.52 Photographic or other reproductions of Government obligations. Nothing...authorize the microfilming or other reproduction of (a) Currency or other...

  8. 31 CFR 1010.940 - Photographic or other reproductions of Government obligations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Photographic or other reproductions of Government obligations. 1010...1010.940 Photographic or other reproductions of Government obligations. Nothing...authorize the microfilming or other reproduction of: (a) Currency or other...

  9. 31 CFR 1010.940 - Photographic or other reproductions of Government obligations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Photographic or other reproductions of Government obligations. 1010...1010.940 Photographic or other reproductions of Government obligations. Nothing...authorize the microfilming or other reproduction of: (a) Currency or other...

  10. 31 CFR 1010.940 - Photographic or other reproductions of Government obligations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Photographic or other reproductions of Government obligations. 1010...1010.940 Photographic or other reproductions of Government obligations. Nothing...authorize the microfilming or other reproduction of: (a) Currency or other...

  11. 18 CFR 292.303 - Electric utility obligations under this subpart.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Electric utility obligations under this subpart...AND COGENERATION Arrangements Between Electric Utilities and Qualifying Cogeneration...Policies Act of 1978 § 292.303 Electric utility obligations under this...

  12. 12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 false Obligations of Funding Corporation; no adverse claims. ...DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION BOOK-ENTRY PROCEDURE § 1511.5 Obligations of Funding Corporation; no adverse...

  13. 12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 false Obligations of Funding Corporation; no adverse claims. ...DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION BOOK-ENTRY PROCEDURE § 1511.5 Obligations of Funding Corporation; no adverse...

  14. 12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 false Obligations of Funding Corporation; no adverse claims. ...DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION BOOK-ENTRY PROCEDURE § 1511.5 Obligations of Funding Corporation; no adverse...

  15. 12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 false Obligations of Funding Corporation; no adverse claims. ...DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION BOOK-ENTRY PROCEDURE § 1511.5 Obligations of Funding Corporation; no adverse...

  16. 12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 false Obligations of Funding Corporation; no adverse claims. ...DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION BOOK-ENTRY PROCEDURE § 1511.5 Obligations of Funding Corporation; no adverse...

  17. 28 CFR 45.10 - Procedures to promote compliance with crime victims' rights obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Procedures to promote compliance with crime victims' rights obligations. 45.10... Procedures to promote compliance with crime victims' rights obligations. (a...that relate to protection of the rights of crime victims. See 18 U.S.C. 3771....

  18. 42 CFR 1004.10 - Statutory obligations of practitioners and other persons.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... false Statutory obligations of practitioners and other persons. 1004.10 Section...IMPOSITION OF SANCTIONS ON HEALTH CARE PRACTITIONERS AND PROVIDERS OF HEALTH CARE SERVICES...1004.10 Statutory obligations of practitioners and other persons. It is the...

  19. 42 CFR 1004.10 - Statutory obligations of practitioners and other persons.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... false Statutory obligations of practitioners and other persons. 1004.10 Section...IMPOSITION OF SANCTIONS ON HEALTH CARE PRACTITIONERS AND PROVIDERS OF HEALTH CARE SERVICES...1004.10 Statutory obligations of practitioners and other persons. It is the...

  20. 42 CFR 1004.10 - Statutory obligations of practitioners and other persons.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... false Statutory obligations of practitioners and other persons. 1004.10 Section...IMPOSITION OF SANCTIONS ON HEALTH CARE PRACTITIONERS AND PROVIDERS OF HEALTH CARE SERVICES...1004.10 Statutory obligations of practitioners and other persons. It is the...

  1. 42 CFR 1004.10 - Statutory obligations of practitioners and other persons.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... false Statutory obligations of practitioners and other persons. 1004.10 Section...IMPOSITION OF SANCTIONS ON HEALTH CARE PRACTITIONERS AND PROVIDERS OF HEALTH CARE SERVICES...1004.10 Statutory obligations of practitioners and other persons. It is the...

  2. 42 CFR 1004.10 - Statutory obligations of practitioners and other persons.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... false Statutory obligations of practitioners and other persons. 1004.10 Section...IMPOSITION OF SANCTIONS ON HEALTH CARE PRACTITIONERS AND PROVIDERS OF HEALTH CARE SERVICES...1004.10 Statutory obligations of practitioners and other persons. It is the...

  3. Origins, Diversity, and Diversification of the Native Hawaiian Leafhoppers (Hemiptera: Cicadellidae: Nesophrosyne) and Their Obligate Endosymbionts

    E-print Network

    O'Grady, Patrick M.

    Origins, Diversity, and Diversification of the Native Hawaiian Leafhoppers (Hemiptera: Cicadellidae Leafhoppers (Hemiptera: Cicadellidae: Nesophrosyne) and Their Obligate Endosymbionts Copyright 2012 By Gordon Leafhoppers (Hemiptera: Cicadellidae: Nesophrosyne) and Their Obligate Endosymbionts by Gordon Morse Bennett

  4. 43 CFR 3137.76 - What happens if I do not meet a continuing development obligation?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...happens if I do not meet a continuing development obligation? 3137.76 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.76 ...happens if I do not meet a continuing development obligation? (a) After...

  5. 43 CFR 3137.71 - What must I do to meet continuing development obligations?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...What must I do to meet continuing development obligations? 3137.71 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.71 What must I do to meet continuing development obligations? (a) Once you...

  6. 47 CFR 14.61 - Obligations with respect to internet browsers built into mobile phones.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... false Obligations with respect to internet browsers built into mobile phones...EQUIPMENT BY PEOPLE WITH DISABILITIES Internet Browsers Built Into Telephones Used With...14.61 Obligations with respect to internet browsers built into mobile phones....

  7. 47 CFR 14.61 - Obligations with respect to internet browsers built into mobile phones.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... false Obligations with respect to internet browsers built into mobile phones...EQUIPMENT BY PEOPLE WITH DISABILITIES Internet Browsers Built Into Telephones Used With...14.61 Obligations with respect to internet browsers built into mobile phones....

  8. Moral obligations of nurses and physicians in neonatal end-of-life care

    PubMed Central

    Epstein, Elizabeth Gingell

    2013-01-01

    The aim of this study was to explore the obligations of nurses and physicians in providing end-of-life care. Nineteen nurses and 11 physicians from a single newborn intensive care unit participated. Using content analysis, an overarching obligation of creating the best possible experience for infants and parents was identified, within which two categories of obligations (decision making and the end of life itself) emerged. Obligations in decision making included talking to parents and timing withdrawal. End-of-life obligations included providing options, preparing parents, being with, advocating, creating peace and normalcy, and providing comfort. Nurses and physicians perceived obligations in both categories, although nurse obligations centered on the end of life while physician obligations focused on decision making. The findings demonstrate that, although the ultimate goal is shared by both disciplines, the paths to achieving that goal are often different. This has important implications for collaboration, communication, and improving the end of life. PMID:20801960

  9. 32 CFR 220.2 - Statutory obligation of third party payer to pay.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

  10. 32 CFR 220.2 - Statutory obligation of third party payer to pay.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

  11. 32 CFR 220.2 - Statutory obligation of third party payer to pay.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

  12. 32 CFR 220.2 - Statutory obligation of third party payer to pay.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

  13. 32 CFR 220.2 - Statutory obligation of third party payer to pay.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

  14. 40 CFR 152.97 - Rights and obligations of data submitters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Rights and obligations of data submitters. 152.97 Section 152...PROCEDURES Procedures To Ensure Protection of Data Submitters' Rights § 152.97 Rights and obligations of data submitters. (a) Right to be...

  15. 40 CFR 152.97 - Rights and obligations of data submitters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Rights and obligations of data submitters. 152.97 Section 152...PROCEDURES Procedures To Ensure Protection of Data Submitters' Rights § 152.97 Rights and obligations of data submitters. (a) Right to be...

  16. 40 CFR 152.97 - Rights and obligations of data submitters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Rights and obligations of data submitters. 152.97 Section 152...PROCEDURES Procedures To Ensure Protection of Data Submitters' Rights § 152.97 Rights and obligations of data submitters. (a) Right to be...

  17. 40 CFR 152.97 - Rights and obligations of data submitters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Rights and obligations of data submitters. 152.97 Section 152...PROCEDURES Procedures To Ensure Protection of Data Submitters' Rights § 152.97 Rights and obligations of data submitters. (a) Right to be...

  18. SERS nanosensors for intracellular redox potential measurements 

    E-print Network

    Auchinvole, Craig Alexander R

    2012-06-22

    Redox regulation and homeostasis are critically important in the regulation of cell function; however, there are significant challenges in quantitatively measuring and monitoring intracellular redox potentials. The work ...

  19. 26 CFR 1.551-3 - Deduction for obligations of the United States and its instrumentalities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...obligations of the United States and its instrumentalities. 1.551-3 Section 1.551-3...obligations of the United States and its instrumentalities. (a) Each United States...obligations of the United States or its instrumentalities (as specified in sections...

  20. 25 CFR 163.42 - Obligated service and breach of contract.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Obligated service and breach of contract. 163.42 Section 163...Training § 163.42 Obligated service and breach of contract. (a) Obligated service...receipt of the request for waiver. (b) Breach of contract. Any individual who...

  1. 26 CFR 1.1037-1 - Certain exchanges of United States obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...value of $930, at which price such obligation is initially...obligation there was no intention to call it before maturity...the same as the issue price of the obligation...Example 1. (a) A purchases in the market for...old bond). The issue price of the new bond for...

  2. 40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

  3. 40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

  4. 40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

  5. 40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

  6. 40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

  7. 31 CFR 225.4 - Pledge of book-entry Government obligations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

  8. 31 CFR 225.4 - Pledge of book-entry Government obligations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

  9. 31 CFR 225.4 - Pledge of book-entry Government obligations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

  10. 31 CFR 225.4 - Pledge of book-entry Government obligations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

  11. 31 CFR 225.4 - Pledge of book-entry Government obligations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

  12. Origin of a complex key innovation in an obligate insectplant mutualism

    E-print Network

    Krenn, Harald W.

    Origin of a complex key innovation in an obligate insect­plant mutualism Olle Pellmyr* and Harald W. The well known obligate pollination mutualism between yuccas and yucca moths is a major model system. Obligate mutualisms between plants and pollinators provide some of the most apparent examples

  13. Crohn's disease-associated adherent-invasive E. coli are selectively favoured by impaired autophagy to replicate intracellularly.

    PubMed

    Lapaquette, Pierre; Glasser, Anne-Lise; Huett, Alan; Xavier, Ramnik J; Darfeuille-Michaud, Arlette

    2010-01-01

    Ileal lesions in Crohn's disease (CD) patients are colonized by pathogenic adherent-invasive Escherichia coli (AIEC) able to invade and to replicate within intestinal epithelial cells. Recent genome-wide association studies have highlighted the autophagy pathway as being associated with CD risk. In the present study we investigated whether defects in autophagy enhance replication of commensal and pathogenic Escherichia coli and CD-associated AIEC. We show that functional autophagy limits intracellular AIEC replication and that a subpopulation of the intracellular bacteria is located within LC3-positive autophagosomes. In IRGM and ATG16L1 deficient cells intracellular AIEC LF82 bacteria have enhanced replication. Surprisingly autophagy deficiency did not interfere with the ability of intracellular bacteria to survive and/or replicate for any other E. coli strains tested, including non-pathogenic, environmental, commensal, or pathogenic strains involved in gastro enteritis. Together these findings demonstrate a central role for autophagy restraining Adherent-Invasive E. coli strains associated with ileal CD. AIEC infection in patients with polymorphisms in autophagy genes may have a significant impact on the outcome of intestinal inflammation. PMID:19747213

  14. Staphylococcus aureus promotes autophagy by decreasing intracellular cAMP levels

    PubMed Central

    Mestre, María Belén; Colombo, María Isabel

    2012-01-01

    Staphylococcus aureus is an intracellular bacterium responsible for serious infectious processes. This pathogen escapes from the phagolysosomal pathway into the cytoplasm, a strategy that allows intracellular bacterial replication and survival with the consequent killing of the eukaryotic host cell and spreading of the infection. S. aureus is able to secrete several virulence factors such as enzymes and toxins. Our recent findings indicate that the main virulence factor of S. aureus, the pore-forming toxin ?-hemolysin (Hla), is the secreted factor responsible for the activation of an alternative autophagic pathway. We have demonstrated that this noncanonical autophagic response is inhibited by artificially elevating the intracellular levels of cAMP. This effect is mediated by RAPGEF3/EPAC (Rap guanine nucleotide exchange factor (GEF)3/exchange protein activated by cAMP), a cAMP downstream effector that functions as a GEF for the small GTPase Rap. We have presented evidence that RAPGEF3 and RAP2B, through calpain activation, are the proteins involved in the regulation of Hla and S. aureus-induced autophagy. In addition, we have found that both, RAPGEF3 and RAP2B, are recruited to the S. aureus–containing phagosome. Of note, adding purified ?-toxin or infecting the cells with S. aureus leads to a decrease in intracellular cAMP levels, which promotes autophagy induction, a response that favors pathogen intracellular survival, as previously demonstrated. We have identified some key signaling molecules involved in the autophagic response upon infection with a bacterial pathogen, which have important implications in understanding innate immune defense mechanisms. PMID:23047465

  15. The fungal pathogen Cryptococcus neoformans manipulates macrophage phagosome maturation.

    PubMed

    Smith, Leanne M; Dixon, Emily F; May, Robin C

    2015-05-01

    Phagocytosis by cells of the innate immune system, such as macrophages, and the subsequent successful maturation of the phagosome, is key for the clearance of pathogens. The fungal pathogen Cryptococcus?neoformans is known to overcome killing by host phagocytes and both replicate within these cells and also escape via a non-lytic process termed vomocytosis. Here we demonstrate that, during intracellular growth, cryptococci modify phagolysosome maturation. Live cryptococci, but not heat-killed pathogens or inert targets, induce the premature removal of the early phagosome markers Rab5 and Rab11. In addition, significant acidification of the phagosome, calcium flux and protease activity is hindered, thus rendering the phagosome permissive for cryptococcal proliferation. Interestingly, several attenuated cryptococcal mutants retain this ability to subvert phagosomal maturation, suggesting that hitherto unidentified pathogen mechanisms regulate this process. PMID:25394938

  16. Pathogenic adaptations to host-derived antibacterial copper

    PubMed Central

    Chaturvedi, Kaveri S.; Henderson, Jeffrey P.

    2014-01-01

    Recent findings suggest that both host and pathogen manipulate copper content in infected host niches during infections. In this review, we summarize recent developments that implicate copper resistance as an important determinant of bacterial fitness at the host-pathogen interface. An essential mammalian nutrient, copper cycles between copper (I) (Cu+) in its reduced form and copper (II) (Cu2+) in its oxidized form under physiologic conditions. Cu+ is significantly more bactericidal than Cu2+ due to its ability to freely penetrate bacterial membranes and inactivate intracellular iron-sulfur clusters. Copper ions can also catalyze reactive oxygen species (ROS) generation, which may further contribute to their toxicity. Transporters, chaperones, redox proteins, receptors and transcription factors and even siderophores affect copper accumulation and distribution in both pathogenic microbes and their human hosts. This review will briefly cover evidence for copper as a mammalian antibacterial effector, the possible reasons for this toxicity, and pathogenic resistance mechanisms directed against it. PMID:24551598

  17. Recruitment of galectin-3 during cell invasion and intracellular trafficking of Trypanosoma cruzi extracellular amastigotes.

    PubMed

    Machado, Fabrício Castro; Cruz, Lilian; da Silva, Aline Alves; Cruz, Mário Costa; Mortara, Renato Arruda; Roque-Barreira, Maria Cristina; da Silva, Claudio Vieira

    2014-02-01

    The invasion of host cells by the intracellular protozoan Trypanosoma cruzi requires interactions with host cell molecules, and the replication of the parasite requires escape from a parasitophorous vacuole into the host cell cytosol. Galectin-3, a member of ?-galactosidase-binding lectin family, has numerous extracellular and intracellular functions. In this study, we investigated the role of galectin-3 during the invasion and intracellular trafficking of T. cruzi extracellular amastigotes (EAs). Endogenous galectin-3 from mouse peritoneal macrophages accumulated around the pathogen during cell invasion by EAs. In addition, galectin-3 accumulated around parasites after their escape from the parasitophorous vacuole. Thus, galectin-3 behaved as a novel marker of phagolysosome lysis during the infection of host cells by T. cruzi. PMID:24225883

  18. Early Acidification of Phagosomes Containing Brucella suis Is Essential for Intracellular Survival in Murine Macrophages

    Microsoft Academic Search

    FRANCOISE PORTE; JEAN-PIERRE LIAUTARD; STEPHAN KOHLER

    1999-01-01

    Brucella suis is a facultative intracellular pathogen of mammals, residing in macrophage vacuoles. In this work, we studied the phagosomal environment of these bacteria in order to better understand the mechanisms allowing survival and multiplication of B. suis. Intraphagosomal pH in murine J774 cells was determined by measuring the fluorescence intensity of opsonized, carboxyfluorescein-rhodamine- and Oregon Green 488- rhodamine-labeled bacteria.

  19. Plant NBS-LRR proteins in pathogen sensing and host defense

    PubMed Central

    DeYoung, Brody J; Innes, Roger W

    2007-01-01

    Plant proteins belonging to the nucleotide-binding site–leucine-rich repeat (NBS-LRR) family are used for pathogen detection. Like the mammalian Nod-LRR protein ‘sensors’ that detect intracellular conserved pathogen-associated molecular patterns, plant NBS-LRR proteins detect pathogen-associated proteins, most often the effector molecules of pathogens responsible for virulence. Many virulence proteins are detected indirectly by plant NBS-LRR proteins from modifications the virulence proteins inflict on host target proteins. However, some NBS-LRR proteins directly bind pathogen proteins. Association with either a modified host protein or a pathogen protein leads to conformational changes in the amino-terminal and LRR domains of plant NBS-LRR proteins. Such conformational alterations are thought to promote the exchange of ADP for ATP by the NBS domain, which activates ‘downstream’ signaling, by an unknown mechanism, leading to pathogen resistance. PMID:17110940

  20. Flavobacteria as Intracellular Symbionts in Cockroaches

    Microsoft Academic Search

    Claudio Bandi; Giuseppe Damiani; Lorenzo Magrassi; Aldo Grigolo; Renato Fani; Luciano Sacchi

    1994-01-01

    Animal cells are the sole habitat for a variety of bacteria. Molecular sequence data have been used to position a number of these intracellular microorganisms in the overall scheme of eubacterial evolution. Most of them have been classified as proteobacteria or chlamydiae. Here we present molecular evidence placing an intracellular symbiont among the flavobacteria-bacteroides. This microorganism inhabits specialized cells in

  1. Pathogenic Microorganisms in Water

    NSDL National Science Digital Library

    Melissa Lenczewski

    Pathogenic Microorganisms in Water: Traditionally, groundwater has been used without treatment because the soil acts as a filter, removing pathogenic microorganisms. Some potential sources of pathogens (or disease causing organisms) in groundwater include septic tanks, leaking sewer lines, sewage sludge, intentional groundwater recharge with sewage, irrigation with sewage, direct injection of sewage, domestic solid waste disposal (landfills) and sewage oxidation ponds. The objective of the session is to introduce hydrogeologist to the types of microorganisms, sources of pathogens, and a simple exercise that can be incorporated into a hydrogeology class.

  2. Proteomes of host cell membranes modified by intracellular activities of Salmonella enterica.

    PubMed

    Vorwerk, Stephanie; Krieger, Viktoria; Deiwick, Jörg; Hensel, Michael; Hansmeier, Nicole

    2015-01-01

    Intracellular pathogens need to establish a growth-stimulating host niche for survival and replication. A unique feature of the gastrointestinal pathogen Salmonella enterica serovar Typhimurium is the creation of extensive membrane networks within its host. An understanding of the origin and function of these membranes is crucial for the development of new treatment strategies. However, the characterization of this compartment is very challenging, and only fragmentary knowledge of its composition and biogenesis exists. Here, we describe a new proteome-based approach to enrich and characterize Salmonella-modified membranes. Using a Salmonella mutant strain that does not form this unique membrane network as a reference, we identified a high-confidence set of host proteins associated with Salmonella-modified membranes. This comprehensive analysis allowed us to reconstruct the interactions of Salmonella with host membranes. For example, we noted that Salmonella redirects endoplasmic reticulum (ER) membrane trafficking to its intracellular niche, a finding that has not been described for Salmonella previously. Our system-wide approach therefore has the potential to rapidly close gaps in our knowledge of the infection process of intracellular pathogens and demonstrates a hitherto unrecognized complexity in the formation of Salmonella host niches. PMID:25348832

  3. Facultative versus obligate nitrogen fixation strategies and their ecosystem consequences.

    PubMed

    Menge, Duncan N L; Levin, Simon A; Hedin, Lars O

    2009-10-01

    Symbiotic nitrogen (N) fixers are critical components of many terrestrial ecosystems. There is evidence that some N fixers fix N at the same rate regardless of environmental conditions (a strategy we call obligate), while others adjust N fixation to meet their needs (a strategy we call facultative). Although these strategies are likely to have qualitatively different impacts on their environment, the relative effectiveness and ecosystem-level impacts of each strategy have not been explored. Using a simple mathematical model, we determine the best facultative strategy and show that it excludes any obligate strategy (fixer or nonfixer) in our basic model. To provide an explanation for the existence of nonfixers and obligate fixers, we show that both costs of being facultative and time lags inherent in the process of N fixation can select against facultative N fixers and also produce the seemingly paradoxical patterns of sustained N limitation and N richness. Finally, we speculate on why the costs and lags may differ between temperate and tropical regions and thus whether they can explain patterns in both biomes simultaneously. PMID:19694561

  4. Floral scents repel facultative flower visitors, but attract obligate ones

    PubMed Central

    Junker, Robert R.; Blüthgen, Nico

    2010-01-01

    Background and Aims Biological mutualisms rely on communication between partners, but also require protective measures against exploitation. Animal-pollinated flowers need to attract pollinators but also to avoid conflicts with antagonistic consumers. The view of flower visitors as mutualistic and antagonistic agents considers primarily the plants' interest. A classification emphasizing the consumer's point of view, however, may be more useful when considering animal's adaptations to flower visits which may include a tolerance against defensive floral scent compounds. Methods In a meta-analysis covering 18 studies on the responses of animals to floral scents, the animals were assigned to the categories of obligate and facultative flower visitors which considers their dependency on floral resources. Their responses on floral scents were compared. Key Results On average, obligate flower visitors, often corresponding to pollinators, were attracted to floral scent compounds. In contrast, facultative and mainly antagonistic visitors were strongly repelled by floral scents. The findings confirm that floral scents have a dual function both as attractive and defensive cues. Conclusions Whether an animal depends on floral resources determines its response to these signals, suggesting that obligate flower visitors evolved a tolerance against primarily defensive compounds. Therefore, floral scent bouquets in conjunction with nutritious rewards may solve the conflicting tasks of attracting mutualists while repelling antagonists. PMID:20228087

  5. Virulence Plasmids of Nonsporulating Gram-Positive Pathogens

    PubMed Central

    Van Tyne, Daria; Gilmore, Michael S.

    2014-01-01

    SUMMARY Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis. PMID:25544937

  6. Emerging foodborne pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The emergence of new foodborne pathogens is due to a number of factors. An important factor is the globalization of the food supply with the possibility of the introduction of foodborne pathogens from other countries. Animal husbandry, food production, food processing, and food distribution system...

  7. Highly Pathogenic Avian Influenza

    E-print Network

    Boyer, Edmond

    Highly Pathogenic Avian Influenza Virus (H5N1) Outbreak in Captive Wild Birds and Cats, Cambodia Tamao Wildlife Rescue Centre, Cambodia, was affected by the highly pathogenic influenza virus (H5N1). Birds from 26 species died. Influenza virus subtype H5N1 was detected in 6 of 7 species tested. Cats

  8. Emerging Escherichia Pathogen

    PubMed Central

    Permpalung, Nitipong; Sentochnik, Deborah E.

    2013-01-01

    Escherichia hermannii was first identified as a new species in 1982. It has rarely been reported as a human pathogen. We report the first case of E. hermannii as the sole pathogen in a catheter-related bloodstream infection. PMID:23740732

  9. Plant pathogen resistance

    DOEpatents

    Greenberg, Jean T; Jung, Ho Won; Tschaplinski, Timothy

    2012-11-27

    Azelaic acid or its derivatives or analogs induce a robust and a speedier defense response against pathogens in plants. Azelaic acid treatment alone does not induce many of the known defense-related genes but activates a plant's defense signaling upon pathogen exposure.

  10. BACTERIAL WATERBORNE PATHOGENS

    EPA Science Inventory

    Bacterial pathogens are examples of classical etiological agents of waterborne disease. While these agents no longer serve as major threats to U.S. water supplies, they are still important pathogens in areas with substandard sanitation and poor water treatment facilities. In th...

  11. Glacial refugia in pathogens: European genetic structure of anther smut pathogens on Silene latifolia and Silene dioica.

    PubMed

    Vercken, Elodie; Fontaine, Michael C; Gladieux, Pierre; Hood, Michael E; Jonot, Odile; Giraud, Tatiana

    2010-01-01

    Climate warming is predicted to increase the frequency of invasions by pathogens and to cause the large-scale redistribution of native host species, with dramatic consequences on the health of domesticated and wild populations of plants and animals. The study of historic range shifts in response to climate change, such as during interglacial cycles, can help in the prediction of the routes and dynamics of infectious diseases during the impending ecosystem changes. Here we studied the population structure in Europe of two Microbotryum species causing anther smut disease on the plants Silene latifolia and Silene dioica. Clustering analyses revealed the existence of genetically distinct groups for the pathogen on S. latifolia, providing a clear-cut example of European phylogeography reflecting recolonization from southern refugia after glaciation. The pathogen genetic structure was congruent with the genetic structure of its host species S. latifolia, suggesting dependence of the migration pathway of the anther smut fungus on its host. The fungus, however, appeared to have persisted in more numerous and smaller refugia than its host and to have experienced fewer events of large-scale dispersal. The anther smut pathogen on S. dioica also showed a strong phylogeographic structure that might be related to more northern glacial refugia. Differences in host ecology probably played a role in these differences in the pathogen population structure. Very high selfing rates were inferred in both fungal species, explaining the low levels of admixture between the genetic clusters. The systems studied here indicate that migration patterns caused by climate change can be expected to include pathogen invasions that follow the redistribution of their host species at continental scales, but also that the recolonization by pathogens is not simply a mirror of their hosts, even for obligate biotrophs, and that the ecology of hosts and pathogen mating systems likely affects recolonization patterns. PMID:21187901

  12. Processes for managing pathogens.

    PubMed

    Godfree, Alan; Farrell, Joseph

    2005-01-01

    Wastewater contains human, animal, and plant pathogens capable of causing viral, bacterial, or parasitic infections. There are several routes whereby sewage pathogens may affect human health, including direct contact, contamination of food crops, zoonoses, and vectors. The range and numbers of pathogens in municipal wastewater vary with the level of endemic disease in the community, discharges from commercial activities, and seasonal factors. Regulations to control pathogen risk in the United States and Europe arising from land application of biosolids are based on the concept of multiple barriers to the prevention of transmission. The barriers are (i) treatment to reduce pathogen content and vector attraction, (ii) restrictions on crops grown on land to which biosolids have been applied, and (iii) minimum intervals following application and grazing or harvesting. Wastewater treatment reduces number of pathogens in the wastewater by concentrating them with the solids in the sludge. Although some treatment processes are designed specifically to inactivate pathogens, many are not, and the actual mechanisms of microbial inactivation are not fully understood for all processes. Vector attraction is reduced by stabilization (reduction of readily biodegradable material) and/or incorporation immediately following application. Concerns about health risks have renewed interest in the effects of treatment (on pathogens) and advanced treatment methods, and work performed in the United States suggests that Class A pathogen reduction can be achieved less expensively than previously thought. Effective pathogen risk management requires control to the complete chain of sludge treatment, biosolids handling and application, and post-application activities. This may be achieved by adherence to quality management systems based on hazard analysis critical control point (HACCP) principles. PMID:15647539

  13. Regulation of toxin production in the pathogenic clostridia.

    PubMed

    Carter, Glen P; Cheung, Jackie K; Larcombe, Sarah; Lyras, Dena

    2014-01-01

    The genus Clostridium comprises a large, heterogeneous group of obligate anaerobic, Gram-positive spore forming bacilli. Members of this genus are ubiquitous in the environment and although most species are considered saprophytic, several are pathogenic to both humans and animals. These bacteria cause a variety of diseases including neuroparalysis, gas gangrene, necrotic enteritis, food poisoning, toxic shock syndrome and pseudomembraneous colitis, which in most cases arise as a consequence of the production of potent exotoxins. Treatment options are often limited, underscoring the need for new treatment strategies and novel therapeutics. Understanding the fundamental mechanisms and signals that control toxin production in the pathogenic clostridia may lead to the identification of novel therapeutic targets that can be exploited in the development of new antimicrobial agents. PMID:24563915

  14. Take the tube: remodelling of the endosomal system by intracellular Salmonella enterica.

    PubMed

    Liss, Viktoria; Hensel, Michael

    2015-05-01

    Salmonella enterica is a facultative intracellular pathogen residing in a unique host cell-derived membrane compartment, termed Salmonella-containing vacuole or SCV. By the activity of effector proteins translocated by the SPI2-endoced type III secretion system (T3SS), the biogenesis of the SCV is manipulated to generate a habitat permissive for intracellular proliferation. By taking control of the host cell vesicle fusion machinery, intracellular Salmonella creates an extensive interconnected system of tubular membranes arising from vesicles of various origins, collectively termed Salmonella-induced tubules (SIT). Recent work investigated the dynamic properties of these manipulations. New host cell targets of SPI2-T3SS effector proteins were identified. By applying combinations of live cell imaging and ultrastructural analyses, the detailed organization of membrane compartments inhabited and modified by intracellular Salmonella is now available. These studies provided unexpected new details on the intracellular environments of Salmonella. For example, one kind of SIT, the LAMP1-positive Salmonella-induced filaments (SIF), are composed of double-membrane tubules, with an inner lumen containing host cell cytosol and cytoskeletal filaments, and an outer lumen containing endocytosed cargo. The novel findings call for new models for the biogenesis of SCV and SIT and give raise to many open questions we discuss in this review. PMID:25802001

  15. Identification of a Novel Small Non-Coding RNA Modulating the Intracellular Survival of Brucella melitensis

    PubMed Central

    Wang, Yufei; Ke, Yuehua; Xu, Jie; Wang, Ligui; Wang, Tongkun; Liang, Hui; Zhang, Wei; Gong, Chunli; Yuan, Jiuyun; Zhuang, Yubin; An, Chang; Lei, Shuangshuang; Du, Xinying; Wang, Zhoujia; Li, Wenna; Yuan, Xitong; Huang, Liuyu; Yang, Xiaoli; Chen, Zeliang

    2015-01-01

    Bacterial small non-coding RNAs (sRNAs) are gene expression modulators respond to environmental changes, stressful conditions, and pathogenesis. In this study, by using a combined bioinformatic and experimental approach, eight novel sRNA genes were identified in intracellular pathogen Brucella melitensis. BSR0602, one sRNA that was highly induced in stationary phase, was further examined and found to modulate the intracellular survival of B. melitensis. BSR0602 was present at very high levels in vitro under stresses similar to those encountered during infection in host macrophages. Furthermore, BSR0602 was found to be highly expressed in the spleens of infected mice, suggesting its potential role in the control of pathogenesis. BSR0602 targets the mRNAs coding for gntR, a global transcriptional regulator, which is required for B. melitensis virulence. Overexpression of BSR0602 results in distinct reduction in the gntR mRNA level. B. melitensis with high level of BSR0602 is defective in bacteria intracellular survival in macrophages and defective in growth in the spleens of infected mice. Therefore, BSR0602 may directly inhibit the expression of gntR, which then impairs Brucellae intracellular survival and contributes to Brucella infection. Our findings suggest that BSR0602 is responsible for bacterial adaptation to stress conditions and thus modulate B. melitensis intracellular survival.

  16. Stochastic resonance in an intracellular genetic perceptron

    NASA Astrophysics Data System (ADS)

    Bates, Russell; Blyuss, Oleg; Zaikin, Alexey

    2014-03-01

    Intracellular genetic networks are more intelligent than was first assumed due to their ability to learn. One of the manifestations of this intelligence is the ability to learn associations of two stimuli within gene-regulating circuitry: Hebbian-type learning within the cellular life. However, gene expression is an intrinsically noisy process; hence, we investigate the effect of intrinsic and extrinsic noise on this kind of intracellular intelligence. We report a stochastic resonance in an intracellular associative genetic perceptron, a noise-induced phenomenon, which manifests itself in noise-induced increase of response in efficiency after the learning event under the conditions of optimal stochasticity.

  17. Stochastic resonance in an intracellular genetic perceptron.

    PubMed

    Bates, Russell; Blyuss, Oleg; Zaikin, Alexey

    2014-03-01

    Intracellular genetic networks are more intelligent than was first assumed due to their ability to learn. One of the manifestations of this intelligence is the ability to learn associations of two stimuli within gene-regulating circuitry: Hebbian-type learning within the cellular life. However, gene expression is an intrinsically noisy process; hence, we investigate the effect of intrinsic and extrinsic noise on this kind of intracellular intelligence. We report a stochastic resonance in an intracellular associative genetic perceptron, a noise-induced phenomenon, which manifests itself in noise-induced increase of response in efficiency after the learning event under the conditions of optimal stochasticity. PMID:24730883

  18. Module No: 410112Sources of ObligationModule Title: Co-requisite: Effects of ObligationsIntroduction of LawPre-requisite

    E-print Network

    students with the basic as well as advanced knowledge in Sources of Obligation in Jordan Law 2. Develop of this module, a student will be able to: A/1 Understand the basic principles and concepts of obligation. Practical Training (Depends on module Practice Discussions regarding Jordan's civil law texts relevant

  19. Signaling During Pathogen Infection

    NSDL National Science Digital Library

    Sylvia Munter (University of Heidelberg Medical School; Department of Parasitology REV)

    2006-05-16

    Pathogens infect almost every living organism. In animals, including humans, the diversity of pathogens ranges from viruses, bacteria, and unicellular parasites to complex fungi, worms, and arthropods. Because pathogens have coevolved with their hosts and have sometimes been coopted as symbionts or commensals, each pathogen/host pair represents a striking success story of survival that reflects the biological complexity of both parties. All invading microorganisms face similar problems, such as gaining access to their host, achieving successful replication, and spreading to a similar or different host. It is therefore not surprising that many different pathogens target similar organs, cell types, and even molecules to achieve their goals. However, no two microbial parasites appear to be completely alike. Although they often target similar signaling networks, they do so in subtly different ways to achieve the desired outcome. This review has eight figures, three movies, and 139 citations and emphasizes two well-established signaling pathways that are often activated during the interaction of different pathogens with their host cells. It illustrates a small part of how the dissection of host/pathogen interactions can reveal, on a molecular scale, a nature shaped by evolutionary forces that can rival the great descriptions of our macroscopic world.

  20. Nanoparticles for intracellular-targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Paulo, Cristiana S. O.; Pires das Neves, Ricardo; Ferreira, Lino S.

    2011-12-01

    Nanoparticles (NPs) are very promising for the intracellular delivery of anticancer and immunomodulatory drugs, stem cell differentiation biomolecules and cell activity modulators. Although initial studies in the area of intracellular drug delivery have been performed in the delivery of DNA, there is an increasing interest in the use of other molecules to modulate cell activity. Herein, we review the latest advances in the intracellular-targeted delivery of short interference RNA, proteins and small molecules using NPs. In most cases, the drugs act at different cellular organelles and therefore the drug-containing NPs should be directed to precise locations within the cell. This will lead to the desired magnitude and duration of the drug effects. The spatial control in the intracellular delivery might open new avenues to modulate cell activity while avoiding side-effects.

  1. Introduction Magnetotactic bacteria (MTB) biomineralize intracellular, membrane-

    E-print Network

    Walker, Lawrence R.

    Introduction Magnetotactic bacteria (MTB) biomineralize intracellular, membrane- bounded, magnetic in the environment. Abstract Magnetotactic bacteria is the categorical name for a group of prokaryotes of this study is on two magnetite-producing, magnetotactic sulfate-reducing bacteria (SRB), Desulfovibrio

  2. Killing dental pathogens using antibacterial graphene oxide.

    PubMed

    He, Jianliang; Zhu, Xiaodan; Qi, Zhengnan; Wang, Chang; Mao, Xiaojun; Zhu, Cailian; He, Zhiyan; Li, Mingyu; Tang, Zisheng

    2015-03-11

    Dental caries and periodontal diseases have a close relationship with microbes such as Streptococcus mutans, Porphyromonas gingivalis and Fusobacterium nucleatum. Graphene oxide (GO), as the derivative of graphene, plays an important role in many areas including biology and medicine. In particular, it has been known as a promising antimicrobial nanomaterial. In this study, we focused on the antimicrobial property of GO against dental pathogens. With the utilization of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduced test, colony forming units (CFU) counting, growth curve observation, live/dead fluorescent staining, and confocal laser scanning microscopy (CLSM), we found GO nanosheets were highly effective in inhibiting the growth of dental pathogens. Transmission electron microscopy (TEM) images revealed that the cell wall and membrane of bacteria lost their integrity and the intracellular contents leaked out after they were treated by GO. Therefore, GO nanosheets would be an effective antibacterial material against dental pathogens and the potential applications in dental care and therapy are promising. PMID:25705785

  3. Tapping into molecular conversation between oomycete plant pathogens and their hosts

    Microsoft Academic Search

    Mahmut Tör

    Several plant pathogenic oomycetes have been under investigation using modern molecular approaches. Genome sequencing and\\u000a annotations are underway or near to completion for some of the species. Pathogen-associated molecular pattern molecules (PAMPs)\\u000a and effector molecules perform inter- and intracellular tasks as adaptation factors and manipulators of the defence network.\\u000a Hundreds of secreted putative effectors have been discovered and conserved molecular

  4. Tapping into molecular conversation between oomycete plant pathogens and their hosts

    Microsoft Academic Search

    Mahmut Tör

    2008-01-01

    Several plant pathogenic oomycetes have been under investigation using modern molecular approaches. Genome sequencing and\\u000a annotations are underway or near to completion for some of the species. Pathogen-associated molecular pattern molecules (PAMPs)\\u000a and effector molecules perform inter- and intracellular tasks as adaptation factors and manipulators of the defence network.\\u000a Hundreds of secreted putative effectors have been discovered and conserved molecular

  5. Coxiella burnetii effector proteins that localize to the parasitophorous vacuole membrane promote intracellular replication.

    PubMed

    Larson, Charles L; Beare, Paul A; Voth, Daniel E; Howe, Dale; Cockrell, Diane C; Bastidas, Robert J; Valdivia, Raphael H; Heinzen, Robert A

    2015-02-01

    The intracellular bacterial pathogen Coxiella burnetii directs biogenesis of a parasitophorous vacuole (PV) that acquires host endolysosomal components. Formation of a PV that supports C. burnetii replication requires a Dot/Icm type 4B secretion system (T4BSS) that delivers bacterial effector proteins into the host cell cytosol. Thus, a subset of T4BSS effectors are presumed to direct PV biogenesis. Recently, the PV-localized effector protein CvpA was found to promote C. burnetii intracellular growth and PV expansion. We predict additional C. burnetii effectors localize to the PV membrane and regulate eukaryotic vesicle trafficking events that promote pathogen growth. To identify these vacuolar effector proteins, a list of predicted C. burnetii T4BSS substrates was compiled using bioinformatic criteria, such as the presence of eukaryote-like coiled-coil domains. Adenylate cyclase translocation assays revealed 13 proteins were secreted in a Dot/Icm-dependent fashion by C. burnetii during infection of human THP-1 macrophages. Four of the Dot/Icm substrates, termed Coxiella vacuolar protein B (CvpB), CvpC, CvpD, and CvpE, labeled the PV membrane and LAMP1-positive vesicles when ectopically expressed as fluorescently tagged fusion proteins. C. burnetii ?cvpB, ?cvpC, ?cvpD, and ?cvpE mutants exhibited significant defects in intracellular replication and PV formation. Genetic complementation of the ?cvpD and ?cvpE mutants rescued intracellular growth and PV generation, whereas the growth of C. burnetii ?cvpB and ?cvpC was rescued upon cohabitation with wild-type bacteria in a common PV. Collectively, these data indicate C. burnetii encodes multiple effector proteins that target the PV membrane and benefit pathogen replication in human macrophages. PMID:25422265

  6. A bacterial siren song: intimate interactions between neutrophils and pathogenic Neisseria

    PubMed Central

    Criss, Alison K.; Seifert, H. Steven

    2012-01-01

    Preface Neisseria gonorrhoeae and Neisseria meningitidis are Gram-negative bacterial pathogens that are exquisitely adapted for growth at human mucosal surfaces and for efficient transmission between hosts. One factor that is essential to neisserial pathogenesis is the interaction between the bacteria and neutrophils, which are recruited in high numbers during infection. Although this vigorous host response could simply reflect effective immune recognition of the bacteria, there is mounting evidence that in fact these obligate human pathogens manipulate the innate immune response to promote infectious processes. This Review summarizes the mechanisms used by pathogenic neisseriae to resist and modulate the antimicrobial activities of neutrophils. It also details some of the major outstanding questions about the Neisseria–neutrophil relationship and proposes potential benefits of this relationship for the pathogen. PMID:22290508

  7. Proteomics of bacterial pathogens.

    PubMed

    Cash, Phillip

    2003-01-01

    The rapid growth of proteomics that has been built upon the available bacterial genome sequences has opened provided new approaches to the analysis of bacterial functional genomics. In the study of pathogenic bacteria the combined technologies of genomics, proteomics and bioinformatics has provided valuable tools for the study of complex phenomena determined by the action of multiple gene sets. The review considers some of the recent developments in the establishment of proteomic databases as well as attempts to define pathogenic determinants at the level of the proteome for some of the major human pathogens. Proteomics can also provide practical applications through the identification of immunogenic proteins that may be potential vaccine targets as well as in extending our understanding of antibiotic action. There is little doubt that proteomics has provided us with new and valuable information on bacterial pathogens and will continue to be an important source of information in the coming years. PMID:12934927

  8. 10th Circuit narrows obligation for job reassignment under ADA.

    PubMed

    1998-06-26

    [Name removed], an assembler at [name removed], developed chronic dermatitis and muscular injuries. [Name removed] tried to reassign [name removed] to other tasks. When [name removed] returned to work after several months of leave, [name removed] claimed it could not accommodate him. In the resulting suit, the 10th U.S. Circuit Court of Appeals ruled, contrary to Equal Employment Opportunity Commission (EEOC) guidance and decisions by a number of other circuit courts, that employers are not obliged to reassign workers to another position if a disability renders them unable to do their assigned job. PMID:11365519

  9. Porphyromonas gingivalis Evasion of Autophagy and Intracellular Killing by Human Myeloid Dendritic Cells Involves DC-SIGN-TLR2 Crosstalk.

    PubMed

    El-Awady, Ahmed R; Miles, Brodie; Scisci, Elizabeth; Kurago, Zoya B; Palani, Chithra D; Arce, Roger M; Waller, Jennifer L; Genco, Caroline A; Slocum, Connie; Manning, Matthew; Schoenlein, Patricia V; Cutler, Christopher W

    2015-02-01

    Signaling via pattern recognition receptors (PRRs) expressed on professional antigen presenting cells, such as dendritic cells (DCs), is crucial to the fate of engulfed microbes. Among the many PRRs expressed by DCs are Toll-like receptors (TLRs) and C-type lectins such as DC-SIGN. DC-SIGN is targeted by several major human pathogens for immune-evasion, although its role in intracellular routing of pathogens to autophagosomes is poorly understood. Here we examined the role of DC-SIGN and TLRs in evasion of autophagy and survival of Porphyromonas gingivalis in human monocyte-derived DCs (MoDCs). We employed a panel of P. gingivalis isogenic fimbriae deficient strains with defined defects in Mfa-1 fimbriae, a DC-SIGN ligand, and FimA fimbriae, a TLR2 agonist. Our results show that DC-SIGN dependent uptake of Mfa1+P. gingivalis strains by MoDCs resulted in lower intracellular killing and higher intracellular content of P. gingivalis. Moreover, Mfa1+P. gingivalis was mostly contained within single membrane vesicles, where it survived intracellularly. Survival was decreased by activation of TLR2 and/or autophagy. Mfa1+P. gingivalis strain did not induce significant levels of Rab5, LC3-II, and LAMP1. In contrast, P. gingivalis uptake through a DC-SIGN independent manner was associated with early endosomal routing through Rab5, increased LC3-II and LAMP-1, as well as the formation of double membrane intracellular phagophores, a characteristic feature of autophagy. These results suggest that selective engagement of DC-SIGN by Mfa-1+P. gingivalis promotes evasion of antibacterial autophagy and lysosome fusion, resulting in intracellular persistence in myeloid DCs; however TLR2 activation can overcome autophagy evasion and pathogen persistence in DCs. PMID:25679217

  10. Porphyromonas gingivalis Evasion of Autophagy and Intracellular Killing by Human Myeloid Dendritic Cells Involves DC-SIGN-TLR2 Crosstalk

    PubMed Central

    El-Awady, Ahmed R.; Miles, Brodie; Scisci, Elizabeth; Kurago, Zoya B.; Palani, Chithra D.; Arce, Roger M.; Waller, Jennifer L.; Genco, Caroline A.; Slocum, Connie; Manning, Matthew; Schoenlein, Patricia V.; Cutler, Christopher W.

    2015-01-01

    Signaling via pattern recognition receptors (PRRs) expressed on professional antigen presenting cells, such as dendritic cells (DCs), is crucial to the fate of engulfed microbes. Among the many PRRs expressed by DCs are Toll-like receptors (TLRs) and C-type lectins such as DC-SIGN. DC-SIGN is targeted by several major human pathogens for immune-evasion, although its role in intracellular routing of pathogens to autophagosomes is poorly understood. Here we examined the role of DC-SIGN and TLRs in evasion of autophagy and survival of Porphyromonas gingivalis in human monocyte-derived DCs (MoDCs). We employed a panel of P. gingivalis isogenic fimbriae deficient strains with defined defects in Mfa-1 fimbriae, a DC-SIGN ligand, and FimA fimbriae, a TLR2 agonist. Our results show that DC-SIGN dependent uptake of Mfa1+P. gingivalis strains by MoDCs resulted in lower intracellular killing and higher intracellular content of P. gingivalis. Moreover, Mfa1+P. gingivalis was mostly contained within single membrane vesicles, where it survived intracellularly. Survival was decreased by activation of TLR2 and/or autophagy. Mfa1+P. gingivalis strain did not induce significant levels of Rab5, LC3-II, and LAMP1. In contrast, P. gingivalis uptake through a DC-SIGN independent manner was associated with early endosomal routing through Rab5, increased LC3-II and LAMP-1, as well as the formation of double membrane intracellular phagophores, a characteristic feature of autophagy. These results suggest that selective engagement of DC-SIGN by Mfa-1+P. gingivalis promotes evasion of antibacterial autophagy and lysosome fusion, resulting in intracellular persistence in myeloid DCs; however TLR2 activation can overcome autophagy evasion and pathogen persistence in DCs. PMID:25679217

  11. Human Pathogen Importation Importing "Human" Pathogens from Outside Canada

    E-print Network

    Human Pathogen Importation Importing "Human" Pathogens from Outside Canada 1) Permits.gc.ca/ols-bsl/pathogen/index.html and scroll to the bottom of the page where you can download the "Application for Permit to Import Human Human Pathogens" and "CL2 Checklist" to PHAC at (613) 941-0596. There are no fees for this service. 5

  12. Intracellular Vibrio parahaemolyticus Escapes the Vacuole and Establishes a Replicative Niche in the Cytosol of Epithelial Cells

    PubMed Central

    de Souza Santos, Marcela

    2014-01-01

    ABSTRACT Vibrio parahaemolyticus is a globally disseminated Gram-negative marine bacterium and the leading cause of seafood-borne acute gastroenteritis. Pathogenic bacterial isolates encode two type III secretion systems (T3SS), with the second system (T3SS2) considered the main virulence factor in mammalian hosts. For many decades, V. parahaemolyticus has been studied as an exclusively extracellular bacterium. However, the recent characterization of the T3SS2 effector protein VopC has suggested that this pathogen has the ability to invade, survive, and replicate within epithelial cells. Herein, we characterize this intracellular lifestyle in detail. We show that following internalization, V. parahaemolyticus is contained in vacuoles that develop into early endosomes, which subsequently mature into late endosomes. V. parahaemolyticus then escapes into the cytoplasm prior to vacuolar fusion with lysosomes. Vacuolar acidification is an important trigger for this escape. The cytoplasm serves as the pathogen’s primary intracellular replicative niche; cytosolic replication is rapid and robust, with cells often containing over 150 bacteria by the time of cell lysis. These results show how V. parahaemolyticus successfully establishes an intracellular lifestyle that could contribute to its survival and dissemination during infection. PMID:25205094

  13. From the Cover: Candicidin-producing Streptomyces support leaf-cutting ants to protect their fungus garden against the pathogenic fungus Escovopsis

    Microsoft Academic Search

    Susanne Haeder; Rainer Wirth; Hubert Herz; Dieter Spiteller

    2009-01-01

    Leaf-cutting ants such as Acromyrmex octospinosus live in obligate symbiosis with fungi of the genus Leucoagaricus, which they grow with harvested leaf material. The symbiotic fungi, in turn, serve as a major food source for the ants. This mutualistic relation is disturbed by the specialized pathogenic fungus Escovopsis sp., which can overcome Leucoagaricus sp. and thus destroy the ant colony.

  14. 76 FR 74721 - Reexamination of Roaming Obligations of Commercial Mobile Radio Service Providers and Other...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-01

    ...FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 20...Roaming Obligations of Commercial Mobile Radio Service Providers and Other Providers of Mobile Data Services AGENCY: Federal Communications Commission. ACTION:...

  15. Evolution of obligate pollination mutualism in New Caledonian Phyllanthus (Euphorbiaceae).

    PubMed

    Kawakita, Atsushi; Kato, Makoto

    2004-03-01

    About half a dozen obligate pollination mutualisms between plants and their seed-consuming pollinators are currently recognized, including fig-fig wasp, yucca-yucca moth, and the recently discovered Glochidion tree-Epicephala moth mutualisms. A common principle among these interactions is that the pollinators consume only a limited amount of the seed crop within a developing fruit (or fig in the case of fig-fig wasp mutualism), thereby ensuring a net benefit to plant reproduction. A novel obligate, seed-parasitic pollination mutualism between two species of New Caledonian Phyllanthus (Euphorbiaceae), a close relative of Glochidion, and Epicephala moths (Gracillariidae) is an exception to this principle. The highly specialized flowers of Phyllanthus are actively and exclusively pollinated by species-specific Epicephala moths, whose larvae consume all six ovules of the developing fruit. Some flowers pollinated by the moths remain untouched, and thus a fraction of the fruits is left intact. Additional evidence for a similar association of Epicephala moths in other Phyllanthus species suggests that this interaction is a coevolved, species-specific pollination mutualism. Implications for the evolutionary stability of the system, as well as differences in mode of interaction with respect to the Glochidion-Epicephala mutualism, are discussed. PMID:21653396

  16. The Evolutionary Pathway to Obligate Scavenging in Gyps Vultures

    PubMed Central

    Dermody, Brian J.; Tanner, Colby J.; Jackson, Andrew L.

    2011-01-01

    The evolutionary pathway to obligate scavenging in Gyps vultures remains unclear. We propose that communal roosting plays a central role in setting up the information transfer network critical for obligate scavengers in ephemeral environments and that the formation of a flotilla-like foraging group is a likely strategy for foraging Gyps vultures. Using a spatial, individual-based, optimisation model we find that the communal roost is critical for establishing the information network that enables information transfer owing to the spatial-concentration of foragers close to the roost. There is also strong selection pressure for grouping behaviour owing to the importance of maintaining network integrity and hence information transfer during foraging. We present a simple mechanism for grouping, common in many animal species, which has the added implication that it negates the requirement for roost-centric information transfer. The formation of a flotilla-like foraging group also improves foraging efficiency through the reduction of overlapping search paths. Finally, we highlight the importance of consideration of information transfer mechanisms in order to maximise the success of vulture reintroduction programmes. PMID:21931786

  17. Obligate symbionts activate immune system development in the tsetse fly.

    PubMed

    Weiss, Brian L; Maltz, Michele; Aksoy, Serap

    2012-04-01

    Many insects rely on the presence of symbiotic bacteria for proper immune system function. However, the molecular mechanisms that underlie this phenomenon are poorly understood. Adult tsetse flies (Glossina spp.) house three symbiotic bacteria that are vertically transmitted from mother to offspring during this insect's unique viviparous mode of reproduction. Larval tsetse that undergo intrauterine development in the absence of their obligate mutualist, Wigglesworthia, exhibit a compromised immune system during adulthood. In this study, we characterize the immune phenotype of tsetse that develop in the absence of all of their endogenous symbiotic microbes. Aposymbiotic tsetse (Glossina morsitans morsitans [Gmm(Apo)]) present a severely compromised immune system that is characterized by the absence of phagocytic hemocytes and atypical expression of immunity-related genes. Correspondingly, these flies quickly succumb to infection with normally nonpathogenic Escherichia coli. The susceptible phenotype exhibited by Gmm(Apo) adults can be reversed when they receive hemocytes transplanted from wild-type donor flies prior to infection. Furthermore, the process of immune system development can be restored in intrauterine Gmm(Apo) larvae when their mothers are fed a diet supplemented with Wigglesworthia cell extracts. Our finding that molecular components of Wigglesworthia exhibit immunostimulatory activity within tsetse is representative of a novel evolutionary adaptation that steadfastly links an obligate symbiont with its host. PMID:22368278

  18. Inhibition of the PtdIns(5) kinase PIKfyve disrupts intracellular replication of Salmonella

    PubMed Central

    Kerr, Markus C; Wang, Jack T H; Castro, Natalie A; Hamilton, Nicholas A; Town, Liam; Brown, Darren L; Meunier, Frederic A; Brown, Nat F; Stow, Jennifer L; Teasdale, Rohan D

    2010-01-01

    3-phosphorylated phosphoinositides (3-PtdIns) orchestrate endocytic trafficking pathways exploited by intracellular pathogens such as Salmonella to gain entry into the cell. To infect the host, Salmonellae subvert its normal macropinocytic activity, manipulating the process to generate an intracellular replicative niche. Disruption of the PtdIns(5) kinase, PIKfyve, be it by interfering mutant, siRNA-mediated knockdown or pharmacological means, inhibits the intracellular replication of Salmonella enterica serovar typhimurium in epithelial cells. Monitoring the dynamics of macropinocytosis by time-lapse 3D (4D) videomicroscopy revealed a new and essential role for PI(3,5)P2 in macropinosome-late endosome/lysosome fusion, which is distinct from that of the small GTPase Rab7. This PI(3,5)P2-dependent step is required for the proper maturation of the Salmonella-containing vacuole (SCV) through the formation of Salmonella-induced filaments (SIFs) and for the engagement of the Salmonella pathogenicity island 2-encoded type 3 secretion system (SPI2-T3SS). Finally, although inhibition of PIKfyve in macrophages did inhibit Salmonella replication, it also appears to disrupt the macrophage's bactericidal response. PMID:20300065

  19. Esterified trityl radicals as intracellular oxygen probes.

    PubMed

    Liu, Yangping; Villamena, Frederick A; Sun, Jian; Wang, Tse-yao; Zweier, Jay L

    2009-04-01

    Triarylmethyl (trityl) radicals exhibit high stability and narrow linewidth under physiological conditions which provide high sensitivity and resolution for the measurement of O2 concentrations, making them attractive as EPR oximetry probes. However, the application of previously available compounds has been limited by their poor intracellular permeability. We recently reported the synthesis and characterization of esterified trityl radicals as potential intracellular EPR probes and their oxygen sensitivity, redox properties, and enzyme-mediated hydrolysis were investigated. In this paper, we report the cellular permeability and stability of these trityls in the presence of bovine aortic endothelial cells. Results show that the acetoxymethoxycarbonyl-containing trityl AMT-02 exhibits high stability in the presence of cells and can be effectively internalized. The intracellular hydrolysis of AMT-02 to the carboxylate form of the trityl (CT-03) was also observed. In addition, this internalized trityl probe was applied to measure intracellular O2 concentrations and the effects of menadione and KCN on the rates of O2 consumption in endothelial cells. This study demonstrates that these esterified trityl radicals can function as effective EPR oximetry probes measuring intracellular O2 concentration and consumption. PMID:19135524

  20. Natural killer (NK) cells contribute to the innate immune defence against tumours and microbial pathogens. They

    E-print Network

    Utrecht, Universiteit

    to distinguish between normal cells and transformed cells or cells infected with intracellular pathogens1 (BOX 1 receptors expressed by NK cells that detect alterations in the cell surface of the infected or transformed, which emphasizes the importance of NK cells in host defence. Although NK cells were initially identified