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1

Advances in Genetic Manipulation of Obligate Intracellular Bacterial Pathogens  

PubMed Central

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

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

2011-01-01

2

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

PubMed Central

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

Corsaro, Daniele; Greub, Gilbert

2006-01-01

3

An Optimal Method of Iron Starvation of the Obligate Intracellular Pathogen, Chlamydia Trachomatis  

PubMed Central

Iron is an essential cofactor in a number of critical biochemical reactions, and as such, its acquisition, storage, and metabolism is highly regulated in most organisms. The obligate intracellular bacterium, Chlamydia trachomatis experiences a developmental arrest when iron within the host is depleted. The nature of the iron starvation response in Chlamydia is relatively uncharacterized because of the likely inefficient method of iron depletion, which currently relies on the compound deferoxamine mesylate (DFO). Inefficient induction of the iron starvation response precludes the identification of iron-regulated genes. This report evaluated DFO with another iron chelator, 2,2?-bipyridyl (Bpdl) and presented a systematic comparison of the two across a range of criteria. We demonstrate that the membrane permeable Bpdl was superior to DFO in the inhibition of chlamydia development, the induction of aberrant morphology, and the induction of an iron starvation transcriptional response in both host and bacteria. Furthermore, iron starvation using Bpdl identified the periplasmic iron-binding protein-encoding ytgA gene as iron-responsive. Overall, the data present a compelling argument for the use of Bpdl, rather than DFO, in future iron starvation studies of chlamydia and other intracellular bacteria. PMID:21687412

Thompson, Christopher C.; Carabeo, Rey A.

2011-01-01

4

Current Biology 16, 16461651, August 22, 2006 2006 Elsevier Ltd All rights reserved DOI 10.1016/j.cub.2006.06.060 The Obligate Intracellular Pathogen  

E-print Network

, the causative agent of tra- choma and many sexually transmitted diseases [2], leads to the accumulation, and signaling [1]. We report that infection with the obligate intracellular pathogen Chlamydia trachomatis and replication in infected cells. The co-option of mammalian LD function by a pathogenic bacterium represents

Valdivia, Raphael

5

Laser microdissection coupled with RNA-seq analysis of porcine enterocytes infected with an obligate intracellular pathogen (Lawsonia intracellularis)  

PubMed Central

Background Lawsonia intracellularis is an obligate intracellular bacterium and the etiologic agent of proliferative enteropathy. The disease is endemic in pigs, emerging in horses and has been described in various other species including nonhuman primates. Cell proliferation is associated with bacterial replication in enterocyte cytoplasm, but the molecular basis of the host-pathogen interaction is unknown. We used laser capture microdissection coupled with RNA-seq technology to characterize the transcriptional responses of infected enterocytes and the host-pathogen interaction. Results Proliferative enterocytes was associated with activation of transcription, protein biosynthesis and genes acting on the G1 phase of the host cell cycle (Rho family). The lack of differentiation in infected enterocytes was demonstrated by the repression of membrane transporters related to nutrient acquisition. The activation of the copper uptake transporter by infected enterocytes was associated with high expression of the Zn/Cu superoxide dismutase by L. intracellularis. This suggests that the intracellular bacteria incorporate intracytoplasmic copper and express a sophisticated mechanism to cope with oxidative stress. Conclusions The feasibility of coupling microdissection and RNA-seq was demonstrated by characterizing the host-bacterial interactions from a specific cell type in a heterogeneous tissue. High expression of L. intracellularis genes encoding hypothetical proteins and activation of host Rho genes infers the role of unrecognized bacterial cyclomodulins in the pathogenesis of proliferative enteropathy. PMID:23800029

2013-01-01

6

Innovative approach for transcriptomic analysis of obligate intracellular pathogen: selective capture of transcribed sequences of Ehrlichia ruminantium  

Microsoft Academic Search

BACKGROUND: Whole genome transcriptomic analysis is a powerful approach to elucidate the molecular mechanisms controlling the pathogenesis of obligate intracellular bacteria. However, the major hurdle resides in the low quantity of prokaryotic mRNAs extracted from host cells. Our model Ehrlichia ruminantium (ER), the causative agent of heartwater, is transmitted by tick Amblyomma variegatum. This bacterium affects wild and domestic ruminants

Loïc Emboulé; France Daigle; Damien F Meyer; Bernard Mari; Valérie Pinarello; Christian Sheikboudou; Virginie Magnone; Roger Frutos; Alain Viari; Pascal Barbry; Dominique Martinez; Thierry Lefrançois; Nathalie Vachiéry

2009-01-01

7

Virulence determinants in the obligate intracellular pathogen Chlamydia trachomatis revealed by forward genetic approaches.  

PubMed

Chlamydia trachomatis, a pathogen responsible for diseases of significant clinical and public health importance, remains poorly characterized because of its intractability to routine molecular genetic manipulation. We have developed a combinatorial approach to rapidly generate a comprehensive library of genetically defined mutants. Chemical mutagenesis, coupled with whole-genome sequencing (WGS) and a system for DNA exchange within infected cells, was used to generate Chlamydia mutants with distinct phenotypes, map the underlying genetic lesions, and generate isogenic strains. As a result, we identified mutants with altered glycogen metabolism, including an attenuated strain defective for type II secretion. The coupling of chemically induced gene variation and WGS to establish genotype-phenotype associations should be broadly applicable to the large list of medically and environmentally important microorganisms currently intractable to genetic analysis. PMID:22232666

Nguyen, Bidong D; Valdivia, Raphael H

2012-01-24

8

Mobile DNA in obligate intracellular bacteria  

Microsoft Academic Search

The small genomes of obligate intracellular bacteria are often presumed to be impervious to mobile DNA and the fluid genetic processes that drive diversification in free-living bacteria. Categorized by reductive evolution and streamlining, the genomes of some obligate intracellular bacteria manifest striking degrees of stability and gene synteny. However, recent findings from complete genome sequences of obligate intracellular species and

William S. Reznikoff; Seth R. Bordenstein

2005-01-01

9

Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth  

PubMed Central

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

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

10

Rickettsia Phylogenomics: Unwinding the Intricacies of Obligate Intracellular Life  

Microsoft Academic Search

BackgroundCompleted 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

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

2008-01-01

11

Rickettsia Phylogenomics: Unwinding the Intricacies of Obligate Intracellular Life  

PubMed Central

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

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

12

Metabolic Interdependence of Obligate Intracellular Bacteria and Their Insect Hosts†  

PubMed Central

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

Zientz, Evelyn; Dandekar, Thomas; Gross, Roy

2004-01-01

13

Genetic regulation of resistance to intracellular pathogens  

Microsoft Academic Search

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

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

1982-01-01

14

Determining the Repertoire of Immunodominant Proteins via Whole-Genome Amplification of Intracellular Pathogens  

PubMed Central

Culturing many obligate intracellular bacteria is difficult or impossible. However, these organisms have numerous adaptations allowing for infection persistence and immune system evasion, making them some of the most interesting to study. Recent advancements in genome sequencing, pyrosequencing and Phi29 amplification, have allowed for examination of whole-genome sequences of intracellular bacteria without culture. We have applied both techniques to the model obligate intracellular pathogen Anaplasma marginale and the human pathogen Anaplasma phagocytophilum, in order to examine the ability of phi29 amplification to determine the sequence of genes allowing for immune system evasion and long-term persistence in the host. When compared to traditional pyrosequencing, phi29-mediated genome amplification had similar genome coverage, with no additional gaps in coverage. Additionally, all msp2 functional pseudogenes from two strains of A. marginale were detected and extracted from the phi29-amplified genomes, highlighting its utility in determining the full complement of genes involved in immune evasion. PMID:22558468

Dark, Michael J.; Lundgren, Anna M.; Barbet, Anthony F.

2012-01-01

15

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

SciTech Connect

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).

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

16

Manipulation of Rab GTPase Function by Intracellular Bacterial Pathogens  

PubMed Central

Summary: Intracellular bacterial pathogens have evolved highly specialized mechanisms to enter and survive within their eukaryotic hosts. In order to do this, bacterial pathogens need to avoid host cell degradation and obtain nutrients and biosynthetic precursors, as well as evade detection by the host immune system. To create an intracellular niche that is favorable for replication, some intracellular pathogens inhibit the maturation of the phagosome or exit the endocytic pathway by modifying the identity of their phagosome through the exploitation of host cell trafficking pathways. In eukaryotic cells, organelle identity is determined, in part, by the composition of active Rab GTPases on the membranes of each organelle. This review describes our current understanding of how selected bacterial pathogens regulate host trafficking pathways by the selective inclusion or retention of Rab GTPases on membranes of the vacuoles that they occupy in host cells during infection. PMID:18063721

Brumell, John H.; Scidmore, Marci A.

2007-01-01

17

Modulation of iron homeostasis in macrophages by bacterial intracellular pathogens  

PubMed Central

Background Intracellular bacterial pathogens depend on acquisition of iron for their success as pathogens. The host cell requires iron as an essential component for cellular functions that include innate immune defense mechanisms. The transferrin receptor TfR1 plays an important part for delivering iron to the host cell during infection. Its expression can be modulated by infection, but its essentiality for bacterial intracellular survival has not been directly investigated. Results We identified two distinct iron-handling scenarios for two different bacterial pathogens. Francisella tularensis drives an active iron acquisition program via the TfR1 pathway program with induction of ferrireductase (Steap3), iron membrane transporter Dmt1, and iron regulatory proteins IRP1 and IRP2, which is associated with a sustained increase of the labile iron pool inside the macrophage. Expression of TfR1 is critical for Francisella's intracellular proliferation. This contrasts with infection of macrophages by wild-type Salmonella typhimurium, which does not require expression of TfR1 for successful intracellular survival. Macrophages infected with Salmonella lack significant induction of Dmt1, Steap3, and IRP1, and maintain their labile iron pool at normal levels. Conclusion The distinction between two different phenotypes of iron utilization by intracellular pathogens will allow further characterization and understanding of host-cell iron metabolism and its modulation by intracellular bacteria. PMID:20184753

2010-01-01

18

Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms  

PubMed Central

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

Mansilla Pareja, Maria Eugenia; Colombo, Maria I.

2013-01-01

19

Fluorogenic Substrate Detection of Viable Intracellular and Extracellular Pathogenic Protozoa  

NASA Astrophysics Data System (ADS)

Viable Leishmania promastigotes and amastigotes were detected by epifluorescence microscopy with fluorescein diacetate being used to mark living parasites and the nucleic acid-binding compound ethidium bromide to stain dead cells. This procedure is superior to other assays because it is faster and detects viable intracellular as well as extracellular Leishmania. Furthermore, destruction of intracellular pathogens by macrophages is more accurately determined with fluorescein diacetate than with other stains. The procedure may have applications in programs to develop drugs and vaccines against protozoa responsible for human and animal disease.

Jackson, Peter R.; Pappas, Michael G.; Hansen, Brian D.

1985-01-01

20

Metabolic host responses to infection by intracellular bacterial pathogens  

PubMed Central

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

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

2013-01-01

21

The Genome of the Obligately Intracellular Bacterium Ehrlichia canis Reveals Themes of Complex Membrane Structure and Immune Evasion Strategies  

SciTech Connect

Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, {alpha}-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, 17 putative pseudogenes, and a substantial proportion of noncoding sequence (27%). 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. Genes associated with pathogen-host interactions were identified, including a small group encoding proteins (n = 12) with tandem repeats and another group encoding proteins with eukaryote-like ankyrin domains (n = 7).

Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Doyle, C Kuyler [Center for Biodenfense and Emerging Infectious Diseases; Lykidis, A [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Francino, M P [U.S. Department of Energy, Joint Genome Institute; Chain, Patrick S [ORNL; Shin, M [U.S. Department of Energy, Joint Genome Institute; Malfatti, Stephanie [Lawrence Livermore National Laboratory (LLNL); Larimer, Frank W [ORNL; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Detter, J C [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Yu, X J [Center for Biodenfense and Emerging Infectious Diseases; Walker, D H [Center for Biodenfense and Emerging Infectious Diseases; McBride, J W [Center for Biodenfense and Emerging Infectious Diseases; Kyripides, N C [U.S. Department of Energy, Joint Genome Institute

2006-01-01

22

Intracellular immunity: finding the enemy within--how cells recognize and respond to intracellular pathogens  

PubMed Central

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

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

2014-01-01

23

Diverse intracellular pathogens activate type III interferon expression from peroxisomes.  

PubMed

Type I interferon responses are considered the primary means by which viral infections are controlled in mammals. Despite this view, several pathogens activate antiviral responses in the absence of type I interferons. The mechanisms controlling type I interferon-independent responses are undefined. We found that RIG-I like receptors (RLRs) induce type III interferon expression in a variety of human cell types, and identified factors that differentially regulate expression of type I and type III interferons. We identified peroxisomes as a primary site of initiation of type III interferon expression, and revealed that the process of intestinal epithelial cell differentiation upregulates peroxisome biogenesis and promotes robust type III interferon responses in human cells. These findings highlight the importance of different intracellular organelles in specific innate immune responses. PMID:24952503

Odendall, Charlotte; Dixit, Evelyn; Stavru, Fabrizia; Bierne, Helene; Franz, Kate M; Durbin, Ann Fiegen; Boulant, Steeve; Gehrke, Lee; Cossart, Pascale; Kagan, Jonathan C

2014-08-01

24

In Vivo Monitoring of Obligate Biotrophic Pathogen Growth by Kinetic PCR  

PubMed Central

The plant kingdom is constantly challenged by a battery of evolving pathogens. New species or races of pathogens are discovered on crops that were initially bred for disease resistance, and globalization is facilitating the movement of exotic pests. Among these pests, obligate biotrophic parasites make up some of the most damaging groups and have been particularly challenging to study. Here we demonstrate the utility of kinetic PCR (kPCR) (real-time PCR, quantitative PCR) to assess the growth of poplar rust, caused by Melampsora species, by quantification of pathogen DNA. kPCR allowed the construction of reliable growth curves from inoculation through the final stages of uredinial maturation, as well as pathogen monitoring before symptoms become visible. Growth parameters, such as latency period, generation time in logarithmic growth, and the increase in DNA mass at saturation, were compared in compatible, incompatible, and nonhost interactions. Pathogen growth was monitored in different applications dealing with plant pathology, such as host and pathogen diversity and transgenic crop improvement. Finally, the capacity of kPCR to differentiate pathogens in the same sample has broad molecular ecology applications for dynamically monitoring the growth of fungi in their environments or in mixed populations or to measure the efficacy of pest control strategies. PMID:15746359

Boyle, Brian; Hamelin, Richard C.; Seguin, Armand

2005-01-01

25

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

Microsoft Academic Search

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

ALAIN C. BORCZUK; MARCIA B. GOLDBERG

1999-01-01

26

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

PubMed Central

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

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

2014-01-01

27

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

PubMed

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

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

2014-01-01

28

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

PubMed Central

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

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

2014-01-01

29

Population and molecular genetics of susceptibility to intracellular pathogens  

Microsoft Academic Search

In the mouse, innate resistance to infection with certain species of Mycobacteria, Salmonella typhimurium and Leishmania donovani is controlled by the expression of a single dominant chromosome 1 gene, designated Bcg. The major effect of the Beg locus is the modulation of the growth rate of these pathogens in cells of the reticuloendothelial tissues during early infection. Using a positional

D. Malo; J. Hu; E. Skamene; E. Schurr

1994-01-01

30

Salmonella enterica Serovar Typhimurium Response Involved in Attenuation of Pathogen Intracellular Proliferation  

PubMed Central

Salmonella enterica serovar Typhimurium proliferates within cultured epithelial and macrophage cells. Intracellular bacterial proliferation is, however, restricted within normal fibroblast cells. To characterize this phenomenon in detail, we investigated the possibility that the pathogen itself might contribute to attenuating the intracellular growth rate. S. enterica serovar Typhimurium mutants were selected in normal rat kidney fibroblasts displaying an increased intracellular proliferation rate. These mutants harbored loss-of-function mutations in the virulence-related regulatory genes phoQ, rpoS, slyA, and spvR. Lack of a functional PhoP-PhoQ system caused the most dramatic change in the intracellular growth rate. phoP- and phoQ-null mutants exhibited an intracellular growth rate 20- to 30-fold higher than that of the wild-type strain. This result showed that the PhoP-PhoQ system exerts a master regulatory function for preventing bacterial overgrowth within fibroblasts. In addition, an overgrowing clone was isolated harboring a mutation in a previously unknown serovar Typhimurium open reading frame, named igaA for intracellular growth attenuator. Mutations in other serovar Typhimurium virulence genes, such as ompR, dam, crp, cya, mviA, spiR (ssrA), spiA, and rpoE, did not result in pathogen intracellular overgrowth. Nonetheless, lack of either SpiA or the alternate sigma factor RpoE led to a substantial decrease in intracellular bacterial viability. These results prove for the first time that specific serovar Typhimurium virulence regulators are involved in a response designed to attenuate the intracellular growth rate within a nonphagocytic host cell. This growth-attenuating response is accompanied by functions that ensure the viability of intracellular bacteria. PMID:11553591

Cano, David A.; Martinez-Moya, Marina; Pucciarelli, M. Graciela; Groisman, Eduardo A.; Casadesus, Josep; Garcia-Del Portillo, Francisco

2001-01-01

31

Salmonella enterica serovar Typhimurium response involved in attenuation of pathogen intracellular proliferation.  

PubMed

Salmonella enterica serovar Typhimurium proliferates within cultured epithelial and macrophage cells. Intracellular bacterial proliferation is, however, restricted within normal fibroblast cells. To characterize this phenomenon in detail, we investigated the possibility that the pathogen itself might contribute to attenuating the intracellular growth rate. S. enterica serovar Typhimurium mutants were selected in normal rat kidney fibroblasts displaying an increased intracellular proliferation rate. These mutants harbored loss-of-function mutations in the virulence-related regulatory genes phoQ, rpoS, slyA, and spvR. Lack of a functional PhoP-PhoQ system caused the most dramatic change in the intracellular growth rate. phoP- and phoQ-null mutants exhibited an intracellular growth rate 20- to 30-fold higher than that of the wild-type strain. This result showed that the PhoP-PhoQ system exerts a master regulatory function for preventing bacterial overgrowth within fibroblasts. In addition, an overgrowing clone was isolated harboring a mutation in a previously unknown serovar Typhimurium open reading frame, named igaA for intracellular growth attenuator. Mutations in other serovar Typhimurium virulence genes, such as ompR, dam, crp, cya, mviA, spiR (ssrA), spiA, and rpoE, did not result in pathogen intracellular overgrowth. Nonetheless, lack of either SpiA or the alternate sigma factor RpoE led to a substantial decrease in intracellular bacterial viability. These results prove for the first time that specific serovar Typhimurium virulence regulators are involved in a response designed to attenuate the intracellular growth rate within a nonphagocytic host cell. This growth-attenuating response is accompanied by functions that ensure the viability of intracellular bacteria. PMID:11553591

Cano, D A; Martínez-Moya, M; Pucciarelli, M G; Groisman, E A; Casadesús, J; García-Del Portillo, F

2001-10-01

32

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

PubMed

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

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

2014-06-01

33

Differential modulation of intracellular survival of cytosolic and vacuolar pathogens by curcumin.  

PubMed

Curcumin, a principal component of turmeric, acts as an immunomodulator regulating the host defenses in response to a diseased condition. The role of curcumin in controlling certain infectious diseases is highly controversial. It is known to alleviate symptoms of Helicobacter pylori infection and exacerbate that of Leishmania infection. We have evaluated the role of curcumin in modulating the fate of various intracellular bacterial pathogens. We show that pretreatment of macrophages with curcumin attenuates the infections caused by Shigella flexneri (clinical isolates) and Listeria monocytogenes and aggravates those caused by Salmonella enterica serovar Typhi CT18 (a clinical isolate), Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Yersinia enterocolitica. Thus, the antimicrobial nature of curcumin is not a general phenomenon. It modulated the intracellular survival of cytosolic (S. flexneri and L. monocytogenes) and vacuolar (Salmonella spp., Y. enterocolitica, and S. aureus) bacteria in distinct ways. Through colocalization experiments, we demonstrated that curcumin prevented the active phagosomal escape of cytosolic pathogens and enhanced the active inhibition of lysosomal fusion by vacuolar pathogens. A chloroquine resistance assay confirmed that curcumin retarded the escape of the cytosolic pathogens, thus reducing their inter- and intracellular spread. We have demonstrated that the membrane-stabilizing activity of curcumin is crucial for its differential effect on the virulence of the bacteria. PMID:22890770

Marathe, Sandhya A; Sen, Minakshi; Dasgupta, Ishani; Chakravortty, Dipshikha

2012-11-01

34

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

PubMed Central

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

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

2011-01-01

35

The adaptor protein CARD9 is required for innate immune responses to intracellular pathogens  

Microsoft Academic Search

The caspase-recruitment domain–containing adaptor protein CARD9 regulates the innate signaling responses to fungal infection. Here we show that CARD9 is required for innate immune responses against intracellular pathogens. We generated Card9?\\/? mice and found that CARD9-deficient macrophages had defects in activation of the kinases p38 and Jnk but not of transcription factor NF-?B after bacterial and viral infection. CARD9-deficient mice

Yen-Michael S Hsu; Yongliang Zhang; Yun You; Donghai Wang; Hongxiu Li; Omar Duramad; Xiao-Feng Qin; Chen Dong; Xin Lin

2006-01-01

36

Naip5 Affects Host Susceptibility to the Intracellular Pathogen Legionella pneumophila  

Microsoft Academic Search

Background:Legionella pneumophila is a gram-negative bacterial pathogen that is the cause of Legionnaires' Disease. Legionella produces disease because it can replicate inside a specialized compartment of host macrophages. Macrophages isolated from various inbred mice exhibit large differences in permissiveness for intracellular replication of Legionella. A locus affecting this host-resistance phenotype, Lgn1, has been mapped to chromosome 13, but the responsible

Sheryl A. Goodart; Joseph D. Growney; Vey Hadinoto; Matthew G. Endrizzi; E. Michelle Long; Keyvan Sadigh; Andrew L. Abney; Isaac Bernstein-Hanley; William F. Dietrich

2003-01-01

37

Identification of a Quorum-Sensing Signal Molecule in the Facultative Intracellular Pathogen Brucella melitensis  

PubMed Central

Brucella melitensis is a gram-negative alpha2-proteobacterium responsible for abortion in goats and for Malta fever in humans. This facultative intracellular pathogen invades and survives within both professional and nonprofessional phagocytes. A dichloromethane extract of spent culture supernatant from B. melitensis induces bioluminescence in an Escherichia coli acyl-homoserine lactone (acyl-HSL) biosensor strain based upon the activity of the LasR protein of Pseudomonas aeruginosa. HPLC fractionation of the extract, followed by mass spectrometry, identified the major active molecule as N-dodecanoylhomoserine lactone (C12-HSL). This is the first report of the production of an acyl-HSL by an intracellular pathogen. The addition of synthetic C12-HSL to an early log phase culture of either B. melitensis or Brucella suis 1330 reduces the transcription of the virB operon, which contains virulence genes known to be required for intracellular survival. This mimics events seen during the stationary phase of growth and suggests that quorum sensing may play a role in the control of virulence in Brucella. PMID:12010991

Taminiau, Bernard; Daykin, Mavis; Swift, Simon; Boschiroli, Maria-Laura; Tibor, Anne; Lestrate, Pascal; De Bolle, Xavier; O'Callaghan, David; Williams, Paul; Letesson, Jean-Jacques

2002-01-01

38

A Transcriptomic Network Identified in Uninfected Macrophages Responding to Inflammation Controls Intracellular Pathogen Survival  

PubMed Central

Summary Intracellular pathogens modulate host cell function to promote their survival. However, in vitro infection studies do not account for the impact of host-derived inflammatory signals. Examining the response of liver-resident macrophages (Kupffer cells) in mice infected with the parasite Leishmania donovani, we identified a transcriptomic network operating in uninfected Kupffer cells exposed to inflammation but absent from Kupffer cells from the same animal that contained intracellular Leishmania. To test the hypothesis that regulated expression of genes within this transcriptomic network might impact parasite survival, we pharmacologically perturbed the activity of retinoid X receptor alpha (RXR?), a key hub within this network, and showed that this intervention enhanced the innate resistance of Kupffer cells to Leishmania infection. Our results illustrate a broadly applicable strategy for understanding the host response to infection in vivo and identify Rxra as the hub of a gene network controlling antileishmanial resistance. PMID:24034621

Beattie, Lynette; d'El-Rei Hermida, Micely; Moore, John W.J.; Maroof, Asher; Brown, Najmeeyah; Lagos, Dimitris; Kaye, Paul M.

2013-01-01

39

HIGS: Host-Induced Gene Silencing in the Obligate Biotrophic Fungal Pathogen Blumeria graminis[W][OA  

PubMed Central

Powdery mildew fungi are obligate biotrophic pathogens that only grow on living hosts and cause damage in thousands of plant species. Despite their agronomical importance, little direct functional evidence for genes of pathogenicity and virulence is currently available because mutagenesis and transformation protocols are lacking. Here, we show that the accumulation in barley (Hordeum vulgare) and wheat (Triticum aestivum) of double-stranded or antisense RNA targeting fungal transcripts affects the development of the powdery mildew fungus Blumeria graminis. Proof of concept for host-induced gene silencing was obtained by silencing the effector gene Avra10, which resulted in reduced fungal development in the absence, but not in the presence, of the matching resistance gene Mla10. The fungus could be rescued from the silencing of Avra10 by the transient expression of a synthetic gene that was resistant to RNA interference (RNAi) due to silent point mutations. The results suggest traffic of RNA molecules from host plants into B. graminis and may lead to an RNAi-based crop protection strategy against fungal pathogens. PMID:20884801

Nowara, Daniela; Gay, Alexandra; Lacomme, Christophe; Shaw, Jane; Ridout, Christopher; Douchkov, Dimitar; Hensel, Gotz; Kumlehn, Jochen; Schweizer, Patrick

2010-01-01

40

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

PubMed Central

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

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

2014-01-01

41

Comparative genome analysis of wheat blue dwarf phytoplasma, an obligate pathogen that causes wheat blue dwarf disease in China.  

PubMed

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

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

2014-01-01

42

Secondary lymphoid organ homing phenotype of human myeloid dendritic cells disrupted by an intracellular oral pathogen.  

PubMed

Several intracellular pathogens, including a key etiological agent of chronic periodontitis, Porphyromonas gingivalis, infect blood myeloid dendritic cells (mDCs). This infection results in pathogen dissemination to distant inflammatory sites (i.e., pathogen trafficking). The alteration in chemokine-chemokine receptor expression that contributes to this pathogen trafficking function, particularly toward sites of neovascularization in humans, is unclear. To investigate this, we utilized human monocyte-derived DCs (MoDCs) and primary endothelial cells in vitro, combined with ex vivo-isolated blood mDCs and serum from chronic periodontitis subjects and healthy controls. Our results, using conditional fimbria mutants of P. gingivalis, show that P. gingivalis infection of MoDCs induces an angiogenic migratory profile. This profile is enhanced by expression of DC-SIGN on MoDCs and minor mfa-1 fimbriae on P. gingivalis and is evidenced by robust upregulation of CXCR4, but not secondary lymphoid organ (SLO)-homing CCR7. This disruption of SLO-homing capacity in response to respective chemokines closely matches surface expression of CXCR4 and CCR7 and is consistent with directed MoDC migration through an endothelial monolayer. Ex vivo-isolated mDCs from the blood of chronic periodontitis subjects, but not healthy controls, expressed a similar migratory profile; moreover, sera from chronic periodontitis subjects expressed elevated levels of CXCL12. Overall, we conclude that P. gingivalis actively "commandeers" DCs by reprogramming the chemokine receptor profile, thus disrupting SLO homing, while driving migration toward inflammatory vascular sites. PMID:24126519

Miles, Brodie; Zakhary, Ibrahim; El-Awady, Ahmed; Scisci, Elizabeth; Carrion, Julio; O'Neill, John C; Rawlings, Aaron; Stern, J Kobi; Susin, Cristiano; Cutler, Christopher W

2014-01-01

43

Intracellular imaging of host-pathogen interactions using combined CARS and two-photon fluorescence microscopies.  

PubMed

Intracellular imaging is a key tool in the investigation of host-pathogen interactions. Advances in this area are particularly sought to understand the effect of viral infection processes on the host cell and its metabolic functions including those cases where host cell lipid metabolism is modulated as a result of infection. We demonstrate the use of combined coherent anti-Stokes Raman scattering (CARS) and two-photon fluorescence microscopies to image fibroblast cells infected by cytomegalovirus. CARS is used to image the host cell membrane, lipid droplets and morphology of the nucleus. Cell nuclei are found to expand during infection, approximately doubling in area. Some cells also show accumulations of lipid droplets at the nuclear periphery. Using a genetically modified virus strain expressing the green fluorescent protein also enables two-photon imaging of the same cells to reveal the location, nature and extent of viral protein expression. PMID:19670191

Robinson, Iain; Ochsenkühn, Michael Andreas; Campbell, Colin J; Giraud, Gerard; Hossack, William J; Arlt, Jochen; Crain, Jason

2010-03-01

44

Search for microRNAs expressed by intracellular bacterial pathogens in infected mammalian cells.  

PubMed

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

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

45

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

PubMed Central

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

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

2013-01-01

46

Intracellular Growth of Legionella pneumophila in Dictyostelium discoideum, a System for Genetic Analysis of Host-Pathogen Interactions  

Microsoft Academic Search

Conditions were established in which Legionella pneumophila, an intracellular bacterial pathogen, could replicate within the unicellular organism Dictyostelium discoideum. By several criteria, L. pneumophila grew by the same mechanism within D. discoideum as it does in amoebae and macrophages. Bacteria grew within membrane-bound vesicles associated with rough endoplasmic reticulum, and L. pneumophila dot\\/icm mutants, blocked for growth in macrophages and

JONATHAN M. SOLOMON; ADAM RUPPER; JAMES A. CARDELLI; RALPH R. ISBERG

2000-01-01

47

Global Analysis of Quorum Sensing Targets in the Intracellular Pathogen Brucella melitensis 16 M  

PubMed Central

Many pathogenic bacteria use a regulatory process termed quorum sensing (QS) to produce and detect small diffusible molecules to synchronize gene expression within a population. In Gram-negative bacteria, the detection of, and response to, these molecules depends on transcriptional regulators belonging to the LuxR family. Such a system has been discovered in the intracellular pathogen Brucella melitensis, a Gram-negative bacterium responsible for brucellosis, a worldwide zoonosis that remains a serious public health concern in countries were the disease is endemic. Genes encoding two LuxR-type regulators, VjbR and BabR, have been identified in the genome of B. melitensis 16 M. A ?vjbR mutant is highly attenuated in all experimental models of infection tested, suggesting a crucial role for QS in the virulence of Brucella. At present, no function has been attributed to BabR. The experiments described in this report indicate that 5% of the genes in the B. melitensis 16 M genome are regulated by VjbR and/or BabR, suggesting that QS is a global regulatory system in this bacterium. The overlap between BabR and VjbR targets suggest a cross-talk between these two regulators. Our results also demonstrate that VjbR and BabR regulate many genes and/or proteins involved in stress response, metabolism, and virulence, including those potentially involved in the adaptation of Brucella to the oxidative, pH, and nutritional stresses encountered within the host. These findings highlight the involvement of QS as a major regulatory system in Brucella and lead us to suggest that this regulatory system could participate in the spatial and sequential adaptation of Brucella strains to the host environment. PMID:20387905

2010-01-01

48

Rapid Pathogen-Induced Apoptosis: A Mechanism Used by Dendritic Cells to Limit Intracellular Replication of Legionella pneumophila  

PubMed Central

Dendritic cells (DCs) are specialized phagocytes that internalize exogenous antigens and microbes at peripheral sites, and then migrate to lymphatic organs to display foreign peptides to naïve T cells. There are several examples where DCs have been shown to be more efficient at restricting the intracellular replication of pathogens compared to macrophages, a property that could prevent DCs from enhancing pathogen dissemination. To understand DC responses to pathogens, we investigated the mechanisms by which mouse DCs are able to restrict replication of the intracellular pathogen Legionella pneumophila. We show that both DCs and macrophages have the ability to interfere with L. pneumophila replication through a cell death pathway mediated by caspase-1 and Naip5. L. pneumophila that avoided Naip5-dependent responses, however, showed robust replication in macrophages but remained unable to replicate in DCs. Apoptotic cell death mediated by caspase-3 was found to occur much earlier in DCs following infection by L. pneumophila compared to macrophages infected similarly. Eliminating the pro-apoptotic proteins Bax and Bak or overproducing the anti-apoptotic protein Bcl-2 were both found to restore L. pneumophila replication in DCs. Thus, DCs have a microbial response pathway that rapidly activates apoptosis to limit pathogen replication. PMID:19521510

Nogueira, Catarina V.; Lindsten, Tullia; Jamieson, Amanda M.; Case, Christopher L.; Shin, Sunny; Thompson, Craig B.; Roy, Craig R.

2009-01-01

49

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

PubMed Central

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

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

2010-01-01

50

The Emerging Human Pathogen Photorhabdus asymbiotica Is a Facultative Intracellular Bacterium and Induces Apoptosis of Macrophage-Like Cells?  

PubMed Central

Photorhabdus species are gram-negative entomopathogenic bacteria of the family Enterobacteriaceae. Among the different members of the genus, one species, Photorhabdus asymbiotica, is a pathogen of both insects and humans. The pathogenicity mechanisms of this bacterium are unknown. Here we show that P. asymbiotica is a facultative intracellular pathogen that is able to replicate inside human macrophage-like cells. Furthermore, P. asymbiotica was shown for the first time in an intracellular location after insect infection. We also demonstrated that among Australian and American clinical isolates, only the Australian strains were able to invade nonphagocytic human cells. In cell culture infection experiments, Australian clinical isolates as well as cell-free bacterial culture supernatant induced strong apoptosis of a macrophage cell line at 6 h postinfection. American isolates also induced cellular death, but much later than that induced by Australian ones. Mammalian cultured cells analyzed for key features of apoptosis displayed apoptotic nuclear morphology, activation of the initiator caspases 8 and 9 and the executioner caspases 3 and 7, and poly(ADP-ribose) polymerase proteolysis, suggesting activation of both the intrinsic and extrinsic apoptotic pathways. PMID:19075024

Costa, S. C. P.; Girard, P. A.; Brehelin, M.; Zumbihl, R.

2009-01-01

51

Two phosphodiesterase genes, PDEL and PDEH, regulate development and pathogenicity by modulating intracellular cyclic AMP levels in Magnaporthe oryzae.  

PubMed

Cyclic AMP (cAMP) signaling plays an important role in regulating multiple cellular responses, such as growth, morphogenesis, and/or pathogenicity of eukaryotic organisms such as fungi. As a second messenger, cAMP is important in the activation of downstream effector molecules. The balance of intracellular cAMP levels depends on biosynthesis by adenylyl cyclases (ACs) and hydrolysis by cAMP phosphodiesterases (PDEases). The rice blast fungus Magnaporthe oryzae contains a high-affinity (PdeH/Pde2) and a low-affinity (PdeL/Pde1) PDEases, and a previous study showed that PdeH has a major role in asexual differentiation and pathogenicity. Here, we show that PdeL is required for asexual development and conidial morphology, and it also plays a minor role in regulating cAMP signaling. This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity. Consistent with both PdeH and PdeL functioning in cAMP signaling, disruption of PDEH only partially rescued the mutant phenotype of ?magB and ?pka1. Further studies suggest that PdeH might function through a feedback mechanism to regulate the expression of pathogenicity factor Mpg1 during surface hydrophobicity and pathogenic development. Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies. PMID:21386978

Zhang, Haifeng; Liu, Kaiyue; Zhang, Xing; Tang, Wei; Wang, Jiansheng; Guo, Min; Zhao, Qian; Zheng, Xiaobo; Wang, Ping; Zhang, Zhengguang

2011-01-01

52

Two Phosphodiesterase Genes, PDEL and PDEH, Regulate Development and Pathogenicity by Modulating Intracellular Cyclic AMP Levels in Magnaporthe oryzae  

PubMed Central

Cyclic AMP (cAMP) signaling plays an important role in regulating multiple cellular responses, such as growth, morphogenesis, and/or pathogenicity of eukaryotic organisms such as fungi. As a second messenger, cAMP is important in the activation of downstream effector molecules. The balance of intracellular cAMP levels depends on biosynthesis by adenylyl cyclases (ACs) and hydrolysis by cAMP phosphodiesterases (PDEases). The rice blast fungus Magnaporthe oryzae contains a high-affinity (PdeH/Pde2) and a low-affinity (PdeL/Pde1) PDEases, and a previous study showed that PdeH has a major role in asexual differentiation and pathogenicity. Here, we show that PdeL is required for asexual development and conidial morphology, and it also plays a minor role in regulating cAMP signaling. This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity. Consistent with both PdeH and PdeL functioning in cAMP signaling, disruption of PDEH only partially rescued the mutant phenotype of ?magB and ?pka1. Further studies suggest that PdeH might function through a feedback mechanism to regulate the expression of pathogenicity factor Mpg1 during surface hydrophobicity and pathogenic development. Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies. PMID:21386978

Zhang, Haifeng; Liu, Kaiyue; Zhang, Xing; Tang, Wei; Wang, Jiansheng; Guo, Min; Zhao, Qian; Zheng, Xiaobo; Wang, Ping; Zhang, Zhengguang

2011-01-01

53

The ``Domino Theory'' of Gene Death: Gradual and Mass Gene Extinction Events in Three Lineages of Obligate Symbiotic Bacterial Pathogens  

E-print Network

extensive genome reduction: Mycobacterium leprae, Shigella flexneri, and Salmonella typhi. We infer additional examples of extensive reductive evolution are Shigella flexneri, a pathogen responsible for many between S. flexneri and Escherichia coli genomes revealed that at least 254 genes have become

Graur, Dan

54

The Francisella pathogenicity island protein IglA localizes to the bacterial cytoplasm and is needed for intracellular growth  

PubMed Central

Background Francisella tularensis is a gram negative, facultative intracellular bacterium that is the etiological agent of tularemia. F. novicida is closely related to F. tularensis but has low virulence for humans while being highly virulent in mice. IglA is a 21 kDa protein encoded by a gene that is part of an iglABCD operon located on the Francisella pathogenicity island (FPI). Results Bioinformatics analysis of the FPI suggests that IglA and IglB are components of a newly described type VI secretion system. In this study, we showed that IglA regulation is controlled by the global regulators MglA and MglB. During intracellular growth IglA production reaches a maximum at about 10 hours post infection. Biochemical fractionation showed that IglA is a soluble cytoplasmic protein and immunoprecipitation experiments demonstrate that it interacts with the downstream-encoded IglB. When the iglB gene was disrupted IglA could not be detected in cell extracts of F. novicida, although IglC could be detected. We further demonstrated that IglA is needed for intracellular growth of F. novicida. A non-polar iglA deletion mutant was defective for growth in mouse macrophage-like cells, and in cis complementation largely restored the wild type macrophage growth phenotype. Conclusion The results of this study demonstrate that IglA and IglB are interacting cytoplasmic proteins that are required for intramacrophage growth. The significance of the interaction may be to secrete effector molecules that affect host cell processes. PMID:17233889

de Bruin, Olle M; Ludu, Jagjit S; Nano, Francis E

2007-01-01

55

Intracellular Persisting Staphylococcus aureus Is the Major Pathogen in Recurrent Tonsillitis  

PubMed Central

Background The two major indications for tonsillectomy are recurrent tonsillitis (RT) and peritonsillar abscess (PTA). Unlike PTAs, which are primarily treated surgically, RT is often cured by tonsillectomy only after a series of failed drug therapy attempts. Although the bacteriological background of RT has been studied, the reason for the lack of success of conservative therapeutic approaches is not well understood. Methods In a prospective study, tonsil specimens from 130 RT patients and 124 PTA patients were examined for the presence of extra- and intracellular bacteria using antibiotic protection assays. Staphylococcus aureus isolates from RT patients were characterized by pulsed-field gel electrophoresis (PFGE), spa-typing and MSCRAMM-gene-PCR. Their ability for biofilm formation was tested and their cell invasiveness was confirmed by a flow cytometric invasion assay (FACS), fluorescent in situ hybridization (FISH) and immunohistochemistry. Findings S. aureus was the predominant species (57.7%) in RT patients, whereas Streptococcus pyogenes was most prevalent (20.2%) in PTA patients. Three different assays (FACS, FISH, antibiotic protection assay) showed that nearly all RT-associated S. aureus strains were located inside tonsillar cells. Correspondingly, the results of the MSCRAMM-gene-PCRs confirmed that 87% of these S. aureus isolates were invasive strains and not mere colonizers. Based upon PFGE analyses of genomic DNA and on spa-gene typing the vast majority of the S. aureus isolates belonged to different clonal lineages. Conclusions Our results demonstrate that intracellular residing S. aureus is the most common cause of RT and indicate that S. aureus uses this location to survive the effects of antibiotics and the host immune response. A German translation of the Abstract is provided as supplementary material (Abstract S1). PMID:20209109

Zautner, Andreas E.; Krause, Merit; Stropahl, Gerhard; Holtfreter, Silva; Frickmann, Hagen; Maletzki, Claudia; Kreikemeyer, Bernd; Pau, Hans Wilhelm; Podbielski, Andreas

2010-01-01

56

Role of PPE18 Protein in Intracellular Survival and Pathogenicity of Mycobacterium tuberculosis in Mice  

PubMed Central

Background Ever since its discovery the mycobacterial proline-proline-glutamic acid (PPE) family of proteins has generated a huge amount of interest. Understanding the role of these proteins in the pathogenesis of Mycobacterium tuberculosis (Mtb) is important. We have demonstrated earlier that the PPE18 protein of Mtb induces IL-10 production in macrophages with subsequent downregulation of pro-inflammatory cytokines like IL-12 and TNF-? and favors a T-helper (Th) 2-type of immune response. Methodology/Principal Findings Using a ppe18 genetic knock-out Mtb strain, we have now carried out infection studies in mice to understand the role of PPE18 in Mtb virulence. The studies reveal that lack of PPE18 leads to attenuation of Mtb in vivo. Mice infected with the ppe18 deleted strain have reduced infection burden in lung, liver and spleen and have better survival rates compared to mice infected with the wild-type Mtb strain. Conclusions/Significance Taken together our data suggest that PPE18 could be a crucial virulence factor for intracellular survival of Mtb. PMID:23300718

Kumar, Santosh; Sharma, Pawan; Mukhopadhyay, Sangita

2012-01-01

57

Insights into the CtrA Regulon in Development of Stress Resistance in Obligatory Intracellular Pathogen Ehrlichia chaffeensis  

PubMed Central

Summary Ehrlichia chaffeensis is an obligate intracellular bacterium that causes human monocytic ehrlichiosis. Ehrlichiae have a biphasic developmental cycle consisting of dense-cored cells (DCs) and reticulate cells (RCs). Isolated DCs are more stress resistant and infectious than RCs. Here, we report that a response regulator, CtrA was upregulated in human monocytes at the late growth stage when DCs develop. E. chaffeensis CtrA bound to the promoters of late-stage transcribed genes: ctrA, ompA (peptidoglycan-associated lipoprotein), bolA (stress-induced morphogen), and surE (stationary phase survival protein), which contain CtrA-binding motifs, and transactivated ompA, surE, and bolA promoter-lacZ fusions in Escherichia coli. OmpA was predominantly expressed in DCs. E. chaffeensis binding to and subsequent infection of monocytes were inhibited by anti-OmpA IgG. E. chaffeensis BolA bound to the promoters of genes encoding outer surface proteins TRP120 and ECH_1038, which were expressed in DCs, and transactivated trp120 and ECH_1038 promoter-lacZ fusions. E. chaffeensis bolA complemented a stress-sensitive E. coli bolA mutant. E. coli expressing E. chaffeensis surE exhibited increased resistance to osmotic stress. Our results suggest that E. chaffeensis CtrA plays a role in coordinating development of the stress resistance for passage from the present to the next host cells through its regulon. PMID:22014113

Cheng, Zhihui; Miura, Koshiro; Popov, Vsevolod L.; Kumagai, Yumi; Rikihisa, Yasuko

2011-01-01

58

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

PubMed Central

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

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

2014-01-01

59

Granulocyte Macrophage-Colony Stimulating Factor-induced Zn Sequestration Enhances Macrophage Superoxide and Limits Intracellular Pathogen Survival  

PubMed Central

SUMMARY Macrophages possess numerous mechanisms to combat microbial invasion, including sequestration of essential nutrients, like 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 and 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 (ROS) 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

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

2013-01-01

60

Biotic and abiotic regulation of resting spore formation in vivo of obligate aphid pathogen Pandora nouryi: modeling analysis and biological implication.  

PubMed

Entomophthoralean fungus Pandora nouryi is an obligate aphid pathogen that enables to produce resting spores (azygospores) for surviving host absence. To explore possible mechanisms involved in the regulation of resting spore formation in vivo, host cohorts consisting of 40-60 nymphs of green peach aphid Myzus persicae produced within 24h on cabbage leaf discs in petri dishes were exposed to spore showers of P. nouryi at the concentrations (C) from a very few to nearly 2000 conidia/mm(2) and then reared for 7-11 days at the regimes of 10-25 degrees C (T) and 8-16 h daylight (H(L)) or ambient (17.5+/-3.1 degrees C, 13:11 L:D). Aphid mortalities observed from 35-83 cohorts (showered separately) at each regime showed typical sigmoid trend and fit well a general logistic equation (0.79pathogen interaction. This indicates the dependence of resting spore formation on the spore concentration. The effects of T and H(L) on P over C were well elucidated by the fitted modified logistic equations P=0.578/{1+exp[1.710-(0.136-0.0053T)C]} and P=0.534/{1+exp[1.639+(0.034-0.0053H(L))C]} (both r(2)=0.79). Our results highlight that the resting spore formation in vivo of P. nouryi is regulated primarily by the concentration of host-infecting conidia discharged from cadavers and facilitated by lower temperature and longer daylight. PMID:19931538

Zhou, Xiang; Feng, Ming-Guang

2010-02-01

61

Invasion of the Central Nervous System by Intracellular Bacteria  

PubMed Central

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

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

2004-01-01

62

Obliging children.  

PubMed

Children may sometimes undergo healthcare procedures that are not intended to improve their health status. Such interventions might include the use of young children as bone marrow donors or their enrolment in non-therapeutic research. One of the justifications used to legitimise these interventions is the premise that children have obligations to others; to their family in the case of related bone marrow transplantation, and to wider society in the case of non-therapeutic research. However, this 'obligation model' (the notion that children possess positive obligations to advance the health status of others) fails as a justificatory paradigm because it is based upon a confusion, identified by Hart, between two notions; that of 'being under an obligation to do something' and that of 'being obliged to do something'. Instead the 'obligation model' is a device employed to put a justificatory gloss upon a consequentialist decision-making process; removing the legitimising gloss allows for a more transparent look at the conflict between parental rights and an individual child's right to bodily integrity. PMID:21289034

Lyons, Barry

2011-01-01

63

Genome-Wide RNAi Screen in IFN-?-Treated Human Macrophages Identifies Genes Mediating Resistance to the Intracellular Pathogen Francisella tularensis  

PubMed Central

Interferon-gamma (IFN-?) inhibits intracellular replication of Francisella tularensis in human monocyte-derived macrophages (HMDM) and in mice, but the mechanisms of this protective effect are poorly characterized. We used genome-wide RNA interference (RNAi) screening in the human macrophage cell line THP-1 to identify genes that mediate the beneficial effects of IFN-? on F. tularensis infection. A primary screen identified ?200 replicated candidate genes. These were prioritized according to mRNA expression in IFN-?-primed and F. tularensis-challenged macrophages. A panel of 20 top hits was further assessed by re-testing using individual shRNAs or siRNAs in THP-1 cells, HMDMs and primary human lung macrophages. Six of eight validated genes tested were also found to confer resistance to Listeria monocytogenes infection, suggesting a broadly shared host gene program for intracellular pathogens. The F. tularensis-validated hits included ‘druggable’ targets such as TNFRSF9, which encodes CD137. Treating HMDM with a blocking antibody to CD137 confirmed a beneficial role of CD137 in macrophage clearance of F. tularensis. These studies reveal a number of important mediators of IFN-? activated host defense against intracellular pathogens, and implicate CD137 as a potential therapeutic target and regulator of macrophage interactions with Francisella tularensis. PMID:22359626

Zhou, Hongwei; DeLoid, Glen; Browning, Erica; Gregory, David J.; Tan, Fengxiao; Bedugnis, Alice S.; Imrich, Amy; Koziel, Henry; Kramnik, Igor; Lu, Quan; Kobzik, Lester

2012-01-01

64

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

PubMed Central

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.

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

2014-01-01

65

Functional characterization of a putative aquaporin from Encephalitozoon cuniculi, a microsporidia pathogenic to humans  

Microsoft Academic Search

The microsporidia are a group of obligate intracellular parasitic protists that have been implicated as both human and veterinary pathogens. The infectious process of these organisms is believed to be dependent upon the rapid influx of water into spores, presumably via aquaporins (AQPs), transmembrane channels that facilitate osmosis. An AQP-like sequence of the microsporidium Encephalitozoon cuniculi (EcAQP), when cloned and

Kaya Ghosh; Clint D. Cappiello; Sean M. McBride; James L. Occi; Ann Cali; Peter M. Takvorian; Thomas V. McDonald; Louis M. Weiss

2006-01-01

66

Complete genome sequence of the Q-fever pathogen Coxiella burnetii  

Microsoft Academic Search

The 1,995,275-bp genome of Coxiella burnetii, Nine Mile phase I RSA493, a highly virulent zoonotic pathogen and category B bioterrorism agent, was sequenced by the random shotgun method. This bacterium is an obligate intracellular acidophile that is highly adapted for life within the eukaryotic phagolysosome. Genome analysis revealed many genes with potential roles in adhesion, invasion, intracellular trafficking, host-cell modulation,

Rekha Seshadri; Ian T. Paulsen; Timothy D. Read; Karen E. Nelson; William C. Nelson; Naomi L. Ward; Hervé Tettelin; Tanja M. Davidsen; Maureen J. Beanan; Robert T. Deboy; Sean C. Daugherty; Lauren M. Brinkac; Ramana Madupu; Robert J. Dodson; Hoda M. Khouri; Kathy H. Lee; Heather A. Carty; David Scanlan; Robert A. Heinzen; Herbert A. Thompson; James E. Samuel; Claire M. Fraser; John F. Heidelberg

2003-01-01

67

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

PubMed

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

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

68

Truncated Hemoglobin, HbN, Is Post-translationally Modified in Mycobacterium tuberculosis and Modulates Host-Pathogen Interactions during Intracellular Infection*  

PubMed Central

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

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.

2013-01-01

69

Characterization of a Lipopolysaccharide-Targeted Monoclonal Antibody and Its Variable Fragments as Candidates for Prophylaxis against the Obligate Intracellular Bacterial Pathogen Coxiella burnetii.  

PubMed

Our previous study demonstrated that treatment of Coxiella burnetii with the phase I lipopolysaccharide (PI-LPS)-targeted monoclonal antibody (MAb) 1E4 significantly inhibited C. burnetii infection in mice, suggesting that 1E4 is a protective MAb. To determine whether passive transfer of antibodies (Abs) can provide protection against C. burnetii natural infection, we examined if passive transfer of 1E4 would protect SCID mice against C. burnetii aerosol infection. The results indicated that 1E4 conferred significant protection against aerosolized C. burnetii, suggesting that 1E4 may be useful for preventing C. burnetii natural infection. To further understand the mechanisms of 1E4-mediated protection and to test the possibility of using humanized 1E4 to prevent C. burnetii infection, we examined whether the Fab fragment of 1E4 (Fab1E4), a recombinant murine single-chain variable fragment (muscFv1E4), and a humanized single-chain variable fragment (huscFv1E4) retained the ability of 1E4 to inhibit C. burnetii infection. The results indicated that Fab1E4, muscFv1E4, and huscFv1E4 were able to inhibit C. burnetii infection in mice but that their ability to inhibit C. burnetii infection was lower than that of 1E4. In addition, treatment of C. burnetii with Fab1E4, muscFv1E4, or huscFv1E4 can block C. burnetii infection of macrophages. Interestingly, treatment of C. burnetii with huscFv1E4 can significantly reduce C. burnetii infectivity in human macrophages. This report provides the first evidence to demonstrate that the humanized variable fragments of an LPS-specific MAb can neutralize C. burnetii infection and appears to be a promising step toward the potential use of a humanized MAb as emergency prophylaxis against C. burnetii exposure. PMID:25114119

Peng, Ying; Schoenlaub, Laura; Elliott, Alexandra; Mitchell, William J; Zhang, Guoquan

2014-11-01

70

Proteome profiling and functional classification of intracellular proteins from conidia of the human-pathogenic mold Aspergillus fumigatus.  

PubMed

Aspergillus fumigatus is a ubiquitously distributed filamentous fungus that has emerged as one of the most serious life-threatening pathogens in immunocompromised patients. The mechanisms for its pathogenicity are poorly understood. Here, we analyzed the proteome of dormant A. fumigatus conidia as the fungal entity having the initial contact with the host. Applying two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), we established a 2-D reference map of conidial proteins. By MALDI-TOF mass spectrometry, we identified a total number of 449 different proteins. We show that 57 proteins of our map are over-represented in resting conidia compared to mycelium. Enzymes involved in reactive oxygen intermediates (ROI) detoxification, pigment biosynthesis, and conidial rodlet layer formation were highly abundant in A. fumigatus spores and most probably account for their enormous stress resistance. Interestingly, pyruvate decarboxylase and alcohol dehydrogenase were detectable in dormant conidia, suggesting that alcoholic fermentation plays a role during dormancy or early germination. Moreover, we show that enzymes for rapid reactivation of protein biosynthesis and metabolic processes are preserved in resting conidia, which therefore feature the potential to immediately respond to an environmental stimulus by germination. The generated data lay the foundations for further proteomic analyses and a better understanding of fungal pathogenesis. PMID:20507060

Teutschbein, Janka; Albrecht, Daniela; Pötsch, Maria; Guthke, Reinhard; Aimanianda, Vishukumar; Clavaud, Cécile; Latgé, Jean-Paul; Brakhage, Axel A; Kniemeyer, Olaf

2010-07-01

71

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

PubMed

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

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

2014-01-01

72

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

PubMed Central

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

Moller, Lars; Schulzke, Joerg D.; Niedrig, Matthias; Bucker, Roland

2014-01-01

73

Codependent and Independent Effects of Nitric Oxide-Mediated Suppression of PhoPQ and Salmonella Pathogenicity Island 2 on Intracellular Salmonella enterica Serovar Typhimurium Survival?  

PubMed Central

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-?)-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-?-primed macrophages in an iNOS-dependent manner, irrespective of the phoQ status of the bacteria. Transcription of spiC is restored in IFN-?-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-?-activated macrophages. PMID:19737903

Bourret, Travis J.; Song, Miryoung; Vazquez-Torres, Andres

2009-01-01

74

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

PubMed Central

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

Han, Seong-Ji; Heinrich, Frederik; Munoz, Melba; Kaiser, Frank; Aebischer, Toni; Buch, Thorsten; Waisman, Ari; Reichmann, Gaby; Utermohlen, Olaf; von Stebut, Esther; von Loewenich, Friederike D.; Bogdan, Christian; Specht, Sabine; Saeftel, Michael; Hoerauf, Achim; Mota, Maria M.; Konen-Waisman, Stephanie; Kaufmann, Stefan H. E.; Howard, Jonathan C.

2011-01-01

75

The Iron-Regulated iupABC Operon Is Required for Saprophytic Growth of the Intracellular Pathogen Rhodococcus equi at Low Iron Concentrations  

PubMed Central

Rhodococcus equi is a facultative intracellular pathogen which proliferates rapidly in both manure-enriched soil and alveolar macrophages. Although both environments are characterized by extremely low concentrations of free iron, very little is known regarding the strategies employed by R. equi to thrive under these conditions. This paper reports the characterization of an R. equi transposome mutant that fails to grow at low iron concentrations. The transposome was shown to be inserted into iupA, the first gene of the iupABC operon encoding an ABC transport system highly similar to siderophore uptake systems. Disruption of the iupA gene also resulted in a failure of R. equi to utilize heme and hemoglobin as a source of iron. Introduction of the iupABC operon in trans restored the wild-type phenotype of the mutant strain. iupABC transcripts were 180-fold more abundant in R. equi grown in iron-depleted medium than in organisms grown in iron-replete medium. Proliferation of the iupABC mutant strain in macrophages was comparable to that of the wild-type strain. Furthermore, the iupABC mutant was not attenuated in mice, showing that the iupABC operon is not required for virulence. PMID:15866930

Miranda-CasoLuengo, Raul; Duffy, Pamela S.; O'Connell, Enda P.; Graham, Brian J.; Mangan, Michael W.; Prescott, John F.; Meijer, Wim G.

2005-01-01

76

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

E-print Network

overview Listeria monocytogenes, Shigella flexneri and Mycobacterium marinum are intracellular bacteria the motility of S. flexneri and target them for destruction by autophagy, an important mechanism of innate

77

Mechanisms of cellular invasion by intracellular parasites.  

PubMed

Numerous disease-causing parasites must invade host cells in order to prosper. Collectively, such pathogens are responsible for a staggering amount of human sickness and death throughout the world. Leishmaniasis, Chagas disease, toxoplasmosis, and malaria are neglected diseases and therefore are linked to socio-economical and geographical factors, affecting well-over half the world's population. Such obligate intracellular parasites have co-evolved with humans to establish a complexity of specific molecular parasite-host cell interactions, forming the basis of the parasite's cellular tropism. They make use of such interactions to invade host cells as a means to migrate through various tissues, to evade the host immune system, and to undergo intracellular replication. These cellular migration and invasion events are absolutely essential for the completion of the lifecycles of these parasites and lead to their for disease pathogenesis. This review is an overview of the molecular mechanisms of protozoan parasite invasion of host cells and discussion of therapeutic strategies, which could be developed by targeting these invasion pathways. Specifically, we focus on four species of protozoan parasites Leishmania, Trypanosoma cruzi, Plasmodium, and Toxoplasma, which are responsible for significant morbidity and mortality. PMID:24221133

Walker, Dawn M; Oghumu, Steve; Gupta, Gaurav; McGwire, Bradford S; Drew, Mark E; Satoskar, Abhay R

2014-04-01

78

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

PubMed Central

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.

Moore, Elizabeth R.; Ouellette, Scot P.

2014-01-01

79

Characterization of a multimeric, eukaryotic prolyl aminopeptidase: an inducible and highly specific intracellular peptidase from the non-pathogenic fungus Talaromyces emersonii  

PubMed Central

Fungi are capable of degrading proteins in their environment by secreting peptidases. However, the link between extracellular digestion and intracellular proteolysis has scarcely been investigated. Mycelial lysates of the filamentous fungus Talaromyces emersonii were screened for intracellular peptidase production. Five distinct proteolytic activities with specificity for the p-nitroanilide (pNA) peptides Suc-AAPF-pNA, Suc-AAA-pNA, K-pNA, F-pNA and P-pNA were identified. The native enzyme responsible for the removal of N-terminal proline residues was purified to homogeneity by ammonium sulfate fractionation followed by five successive chromatographic steps. The enzyme, termed Talaromyces emersonii prolyl aminopeptidase (TePAP), displayed a 50-fold specificity for cleaving N-terminal Pro–X (kcat/Km=2.1×106?M?1?s?1) compared with Ala–X or Val–X bonds. This intracellular aminopeptidase was optimally active at pH?7.4 and 50?°C. Peptide sequencing facilitated the design of degenerate oligonucleotides from homologous sequences encoding putative fungal proline aminopeptidases, enabling subsequent cloning of the gene. TePAP was shown to be relatively uninhibited by classical serine peptidase inhibitors and to be sensitive to selected cysteine- and histidine-modifying reagents, yet gene sequence analysis identified the protein as a serine peptidase with an ?/? hydrolase fold. Northern analysis indicated that Tepap mRNA levels were regulated by the composition of the growth medium. Highest Tepap transcript levels were observed when the fungus was grown in medium containing glucose and the protein hydrolysate casitone. Interestingly, both the induction profile and substrate preference of this enzyme suggest potential co-operativity between extracellular and intracellular proteolysis in this organism. Gel filtration chromatography suggested that the enzyme exists as a 270?kDa homo-hexamer, whereas most bacterial prolyl aminopeptidases (PAPs) are monomers. Phylogenetic analysis of known PAPs revealed two diverse subfamilies that are distinguishable on the basis of primary and secondary structure and appear to correlate with the subunit composition of the native enzymes. Sequence comparisons revealed that PAPs with key conserved topological features are widespread in bacterial and fungal kingdoms, and this study identified many putative PAP candidates within sequenced genomes. This work represents, to our knowledge, the first detailed biochemical and molecular analysis of an inducible PAP from a eukaryote and the first intracellular peptidase isolated from the thermophilic fungus T. emersonii. PMID:19556294

Mahon, Cathal S.; O'Donoghue, Anthony J.; Goetz, David H.; Murray, Patrick G.; Craik, Charles S.; Tuohy, Maria G.

2009-01-01

80

Identification of the clpB and bipA genes and an evaluation of their expression as related to intracellular survival for the bacterial pathogen Piscirickettsia salmonis.  

PubMed

Piscirickettsia salmonis is the pathogen responsible for salmonid rickettsial septicemia (SRS), a disease that affects a wide variety of marine cultivated fish species and causes economic losses for the aquaculture industry worldwide. Many in vitro studies have reported on the capacity of this microorganism to replicate in the interior of cytoplasmic vesicles from varied fish cell lines. However, the mechanisms used by this bacteria to survive, replicate, and propagate in cell lines, especially in macrophages and monocytes, are unknown. A number of studies have described the diverse proteins in pathogens such as Legionella pneumophila, Coxiella burnetii, and Francisella tularensis which allow these to evade the cellular immune response and replicate in the interior of macrophages in different hosts. Some of these proteins are the virulence factor BipA/TypA and the heat shock protein ClpB, both of which have been widely characterized. The results of the current study present the complete coding sequence of the genes clpB and bipA from the P. salmonis genome. Moreover, the experimental results suggest that during the infectious process of the SHK-1 cellular line in P. salmonis, the pathogen significantly increases the expression of proteins ClpB and BipA. This would permit the pathogen to adapt to the hostile conditions produced by the macrophage and thus evade mechanisms of cellular degradation while facilitating replication in the interior of this salmon cell line. PMID:25205198

Isla, A; Haussmann, D; Vera, T; Kausel, G; Figueroa, J

2014-10-10

81

MgtC as a horizontally-acquired virulence factor of intracellular bacterial pathogens: evidence from molecular phylogeny and comparative genomics.  

PubMed

MgtC is a virulence factor required for intramacrophage survival and growth in low Mg2+ medium in two pathogens that are not phylogenetically related, Salmonella typhimurium and Mycobacterium tuberculosis. In S. typhimurium, mgtC is carried by the SPI-3 pathogenicity island and hybridization studies have suggested that the distribution of mgtC among enterobacteria is limited. In the present study, we searched for the presence of mgtC-like sequences in eubacterial genomes. Analyses of MgtC-like proteins phylogeny and mgtC-like chromosomal context support the hypothesis that mgtC has been acquired by horizontal gene transfer repeatedly throughout bacterial evolution. In addition, the phylogenetic analysis revealed the existence of a subgroup of proteins, that includes the S. typhimurium and M. tuberculosis MgtC proteins, as well as MgtC-related proteins from other pathogens that are able to survive in macrophages, B. melitensis and Y. pestis. We propose that MgtC has a similar function in all these distantly related pathogens, most likely providing the ability to grow in a low Mg2+ environment. PMID:14708580

Blanc-Potard, Anne-Béatrice; Lafay, Bénédicte

2003-10-01

82

Identification of Pathogenic Mechanisms of COCH Mutations, Abolished Cochlin Secretion, and Intracellular Aggregate Formation: Genotype-Phenotype Correlations in DFNA9 Deafness and Vestibular Disorder.  

PubMed

Mutations in COCH (coagulation factor C homology) cause autosomal-dominant nonsyndromic 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 von Willebrand factor A (vWFA) domain mutants, which were not transported from the endoplasmic reticulum 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

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

2014-12-01

83

Genome degeneration affects both extracellular and intracellular bacterial endosymbionts  

PubMed Central

The obligate intracellular bacterial endosymbionts of insects are a paradigm for reductive genome evolution. A study published recently in BMC Biology demonstrates that similar evolutionary forces shaping genome structure may also apply to extracellular endosymbionts. PMID:19435469

Feldhaar, Heike; Gross, Roy

2009-01-01

84

Gene Conversion Maintains Nonfunctional Transposable Elements in an Obligate Mutualistic Endosymbiont  

E-print Network

LETTER Gene Conversion Maintains Nonfunctional Transposable Elements in an Obligate Mutualistic that ISs constitute 2.4% of the genome of the obligate mutualistic endosymbiont Wolbachia wBm. AlthoughBm. Mutualistic intracellular symbiosis between bacteria and eukaryotes is a widespread phenomenon that has signif

Cordaux, Richard

85

On public obligation.  

PubMed

Poverty has a potent and provable impact on health, education, opportunity, safety, dignity, and overall quality of life for Americans. This article argues that our obligations to ameliorate poverty are not only private, religious, and charitable, they are public and governmental as well. PMID:23189436

Nichol, Gene R

2012-01-01

86

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

PubMed Central

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

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

2014-01-01

87

Cyclic Diguanylate Signaling Proteins Control Intracellular Growth of Legionella pneumophila  

E-print Network

Cyclic Diguanylate Signaling Proteins Control Intracellular Growth of Legionella pneumophila Assaf, and virulence. The role of cyclic diguanylate signaling in the lifestyle of Legionella pneumophila of Legionnaires' disease, Legionella pneumophila, is an intracellular pathogen that grows inside environmental

88

Guinea pigs sublethally infected with aerosolized Legionella pneumophila develop humoral and cell-mediated immune responses and are protected against lethal aerosol challenge. A model for studying host defense against lung infections caused by intracellular pathogens  

PubMed Central

We have employed the guinea pig model of L. pneumophila infection, which mimics Legionnaires' disease in humans both clinically and pathologically, to study humoral and cell-mediated immune responses to L. pneumophila and to examine protective immunity after aerosol exposure, the natural route of infection. Guinea pigs exposed to sublethal concentrations of L. pneumophila by aerosol developed strong humoral immune responses. By the indirect fluorescent antibody assay, exposed guinea pigs had a median serum antibody titer (expressed as the reciprocal of the highest positive dilution) of 32, whereas control guinea pigs had a median titer of less than 1. Sublethally infected (immunized) guinea pigs also developed strong cell-mediated immune responses. In response to L. pneumophila antigens, splenic lymphocytes from immunized but not control animals proliferated strongly in vitro, as measured by their capacity to incorporate [3H]thymidine. Moreover, immunized but not control guinea pigs developed strong cutaneous delayed-type hypersensitivity to intradermally injected L. pneumophila antigens. Sublethally infected (immunized) guinea pigs exhibited strong protective immunity to L. pneumophila. In two independent experiments, all 22 immunized guinea pigs survived aerosol challenge with one or three times the lethal dose of L. pneumophila whereas none of 16 sham- immunized control guinea pigs survived (p less than 0.0001 in each experiment). Immunized guinea pigs were not protected significantly from challenge with 10 times the lethal dose. Immunized but not control animals cleared the bacteria from their lungs. This study demonstrates that guinea pigs sublethally infected with L. pneumophila by the aerosol route develop strong humoral immune responses to this pathogen, develop strong cell-mediated immune responses and cutaneous delayed- type hypersensitivity to L. pneumophila antigens, are protected against subsequent lethal aerosol challenge, and are able to clear the bacteria from their lungs. The guinea pig model of L. pneumophila pulmonary infection is as an excellent one for studying general principles of host defense against pulmonary infections caused by intracellular pathogens. PMID:3819647

1987-01-01

89

Chlamydial infections of fish: diverse pathogens and emerging causes of disease in aquaculture species.  

PubMed

Chlamydial infections of fish are emerging as an important cause of disease in new and established aquaculture industries. To date, epitheliocystis, a skin and gill disease associated with infection by these obligate intracellular pathogens, has been described in over 90 fish species, including hosts from marine and fresh water environments. Aided by advances in molecular detection and typing, recent years have seen an explosion in the description of these epitheliocystis-related chlamydial pathogens of fish, significantly broadening our knowledge of the genetic diversity of the order Chlamydiales. Remarkably, in most cases, it seems that each new piscine host studied has revealed the presence of a phylogenetically unique and novel chlamydial pathogen, providing researchers with a fascinating opportunity to understand the origin, evolution and adaptation of their traditional terrestrial chlamydial relatives. Despite the advances in this area, much still needs to be learnt about the epidemiology of chlamydial infections in fish if these pathogens are to be controlled in farmed environments. The lack of in vitro methods for culturing of chlamydial pathogens of fish is a major hindrance to this field. This review provides an update on our current knowledge of the taxonomy and diversity of chlamydial pathogens of fish, discusses the impact of these infections on the health, and highlights further areas of research required to understand the biology and epidemiology of this important emerging group of fish pathogens of aquaculture species. PMID:24932463

Stride, M C; Polkinghome, A; Nowak, B F

2014-06-25

90

The outcome of Cryptococcus neoformans intracellular pathogenesis in human monocytes  

Microsoft Academic Search

BACKGROUND: Cryptococcus neoformans is an encapsulated yeast that is a facultative intracellular pathogen. The interaction between macrophages and C. neoformans is critical for extrapulmonary dissemination of this pathogenic yeast. C. neoformans can either lyse macrophages or escape from within them through a process known as phagosomal extrusion. However, most studies of intracellular pathogenesis have been made with mouse cells and

Mauricio Alvarez; Tamika Burns; Yong Luo; Liise-anne Pirofski; Arturo Casadevall

2009-01-01

91

Intracellular Neutralization of Virus by Immunoglobulin A Antibodies  

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

92

Autophagy in intracellular bacterial infection.  

PubMed

Numerous pathogens have developed the capacity to invade host cells to be protected from components of the systemic immune system. However, once in the host cells they utilize sophisticated strategies to avoid the powerful machinery built by the cells to kill invading pathogens. In the last few years cumulative evidence indicates that autophagy is one of the most remarkable tools of the intracellular host cell defense machinery that bacteria must confront upon cell invasion. However, several pathogens subvert the autophagic pathway and, manipulate this process at the molecular level, as a strategy to establish a persistent infection. In this review we have summarized the interaction between autophagy and different bacterial pathogens including those that take advantage of the host cell autophagy, allowing successful colonization, as well as those microorganisms which are controlled by autophagy as part of the innate surveillance mechanism. PMID:19303905

Campoy, Emanuel; Colombo, María I

2009-09-01

93

Classification Revisions Reduce Reported Federal Development Obligations  

NSF Publications Database

... See Related Reports Classification Revisions Reduce Reported Federal Development Obligations by ... reported obligations. For example, if $1 billion previously classified and reported as "development ...

94

[Facultative and obligate pathogenic moulds in skin affections].  

PubMed

Molds are vegetable microorganisms, which differ from dermatophytes sensitive to griseofulvin, and from yeasts, which do not form aerial mycelium. Most of the molds, phytopathogenic or which live from dead organic substances, are apathogenic to humans. Only a couple of dozen species can parasitize on the skin, usually together with dermatophytes or yeasts. Onychomycoses with molds appear mostly in elderly people, and fungus affections of external auditory passage in seborrheic eczema of the ear. The hair can be infected by Piedraia hortae, resulting in hard black nodules. After the identification of molds on the skin, criticism is necessary, since in more than 95% of the cases they are accidental germs. Several cultures and microscopic tests are necessary to assure the diagnosis. Broad-spectrum antimycotics is the predominant choice for treatment, but also amphotericin B, nystatin and pimaricin. PMID:146687

Rieth, H

1978-01-01

95

Ehrlichia chaffeensis: a Prototypical Emerging Pathogen  

PubMed Central

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

Paddock, Christopher D.; Childs, James E.

2003-01-01

96

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...

97

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Teaching obligation. 2400.65 Section 2400... Special Conditions § 2400.65 Teaching obligation. Upon receiving...the Fellow is employed indicating the teaching activities of the Fellow during...

2011-10-01

98

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Teaching obligation. 2400.65 Section 2400... Special Conditions § 2400.65 Teaching obligation. Upon receiving...the Fellow is employed indicating the teaching activities of the Fellow during...

2013-10-01

99

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Teaching obligation. 2400.65 Section 2400... Special Conditions § 2400.65 Teaching obligation. Upon receiving...the Fellow is employed indicating the teaching activities of the Fellow during...

2012-10-01

100

An Update Semantics for Prima Facie Obligations  

Microsoft Academic Search

The deontic logic dus is a deontic update semantics for prescriptive obligations based on the update semantics of Veltman. In dus the denition of logical validity of obligations is not based on static truth values but on dynamic action transitions. In this paper prescriptive prima facie obligations are formalized in update semantics. The logic formalizes the specicity principle, has reinstatement

Leendert W. N. Van Der Torre; Yao-hua Tan

1998-01-01

101

Criblamydia sequanensis, a new intracellular Chlamydiales isolated from Seine river water using amoebal co-culture.  

PubMed

Accumulating evidence supports a role for Chlamydia-related organisms as emerging pathogens for human and animals. Assessment of their pathogenicity requires strain availability, at least for animal models and serological studies. As these obligate intracellular species are able to grow inside amoebae, we used co-culture with Acanthamoeba castellanii in an attempt to recover new Chlamydia-related species from river water. We isolated two strains from eight water samples. The first strain is a new Parachlamydia acanthamoebae strain that differs from previously described isolates by only two bases in the complete 16S rRNA gene sequence. The second isolate is the first representative of a new Chlamydiales family, as demonstrated by genetic and phylogenetic analyses of the 16S rRNA, 23S rRNA, ADP/ATP translocase and RnpB encoding genes. Using fluorescent in situ hybridization and electron microscopy, we demonstrated that it grows in high numbers in amoebae, where it exhibits a Chlamydia-like developmental cycle with reticulate bodies and star-like elementary bodies. Based on these results, we propose to name this new species 'Criblamydia sequanensis'. This work confirmed that amoebal co-culture is a relevant method to isolate new chlamydiae, and that it can be successfully applied to ecosystems colonized with a complex microbial community. PMID:17107554

Thomas, Vincent; Casson, Nicola; Greub, Gilbert

2006-12-01

102

Chlamydiae Assemble a Pathogen Synapse to Hijack the Host Endoplasmic Reticulum  

PubMed Central

Chlamydiae are obligate intracellular bacterial pathogens that replicate within a specialized membrane-bound compartment, termed an ‘inclusion’. The inclusion membrane is a critical host–pathogen interface, yet the extent of its interaction with cellular organelles and the origin of this membrane remain poorly defined. Here we show that the host endoplasmic reticulum (ER) is specifically recruited to the inclusion, and that key rough ER (rER) proteins are enriched on and translocated into the inclusion. rER recruitment is a Chlamydia-orchestrated process that occurs independently of host trafficking. Generation of infectious progeny requires an intact ER, since ER vacuolation early during infection stalls inclusion development, whereas disruption post ER recruitment bursts the inclusion. Electron tomography and immunolabelling of Chlamydia-infected cells reveal ‘pathogen synapses’ at which ordered arrays of chlamydial type III secretion complexes connect to the inclusion membrane only at rER contact sites. Our data show a supramolecular assembly involved in pathogen hijack of a key host organelle. PMID:22901061

Dumoux, Maud; Clare, Daniel K; Saibil, Helen R; Hayward, Richard D

2012-01-01

103

Host-cell interactions with pathogenic Rickettsia species  

PubMed Central

Pathogenic Rickettsia species are Gram-negative, obligate intracellular bacteria responsible for the spotted fever and typhus groups of diseases around the world. It is now well established that a majority of sequelae associated with human rickettsioses are the outcome of the pathogen's affinity for endothelium lining the blood vessels, the consequences of which are vascular inflammation, insult to vascular integrity and compromised vascular permeability, collectively termed ‘Rickettsial vasculitis’. Signaling mechanisms leading to transcriptional activation of target cells in response to Rickettsial adhesion and/or invasion, differential activation of host-cell signaling due to infection with spotted fever versus typhus subgroups of Rickettsiae, and their contributions to the host's immune responses and determination of cell fate are the major subtopics of this review. Also included is a succinct analysis of established in vivo models and their use for understanding Rickettsial interactions with host cells and pathogenesis of vasculotropic rickettsioses. Continued progress in these important but relatively under-explored areas of bacterial pathogenesis research should further highlight unique aspects of Rickettsial interactions with host cells, elucidate the biological basis of endothelial tropism and reveal novel chemotherapeutic and vaccination strategies for debilitating Rickettsial diseases. PMID:19327117

Sahni, Sanjeev K; Rydkina, Elena

2009-01-01

104

NLR functions beyond pathogen recognition  

Microsoft Academic Search

The last 10 years have witnessed the identification of a new class of intracellular pattern-recognition molecules—the nucleotide-binding domain and leucine-rich repeat–containing family (NLR). Members of this family garnered interest as pattern-recognition receptors able to trigger inflammatory responses against pathogens. Many studies support a pathogen-recognition function for human NLR proteins and shed light on their role in the broader control of

Thomas A Kufer; Philippe J Sansonetti

2011-01-01

105

Hijacking of host cellular functions by an intracellular parasite, the microsporidian Anncaliia algerae.  

PubMed

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

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

106

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

PubMed Central

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

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

107

Host metabolism regulates intracellular growth of Trypanosoma cruzi.  

PubMed

Metabolic coupling of intracellular pathogens with host cells is essential for successful colonization of the host. Establishment of intracellular infection by the protozoan Trypanosoma cruzi leads to the development of human Chagas' disease, yet the functional contributions of the host cell toward the infection process remain poorly characterized. Here, a genome-scale functional screen identified interconnected metabolic networks centered around host energy production, nucleotide metabolism, pteridine biosynthesis, and fatty acid oxidation as key processes that fuel intracellular T. cruzi growth. Additionally, the host kinase Akt, which plays essential roles in various cellular processes, was critical for parasite replication. Targeted perturbations in these host metabolic pathways or Akt-dependent signaling pathways modulated the parasite's replicative capacity, highlighting the adaptability of this intracellular pathogen to changing conditions in the host. These findings identify key cellular process regulating intracellular T. cruzi growth and illuminate the potential to leverage host pathways to limit T. cruzi infection. PMID:23332160

Caradonna, Kacey L; Engel, Juan C; Jacobi, David; Lee, Chih-Hao; Burleigh, Barbara A

2013-01-16

108

The Francisella tularensis migR, trmE, and cphA Genes Contribute to F. tularensis Pathogenicity Island Gene Regulation and Intracellular Growth by Modulation of the Stress Alarmone ppGpp  

PubMed Central

The Francisella tularensis pathogenicity island (FPI) encodes many proteins that are required for virulence. Expression of these genes depends upon the FevR (PigR) regulator and its interactions with the MglA/SspA and RNA polymerase transcriptional complex. Experiments to identify how transcription of the FPI genes is activated have led to identification of mutations within the migR, trmE, and cphA genes that decrease FPI expression. Recent data demonstrated that the small alarmone ppGpp, produced by RelA and SpoT, is important for stabilizing MglA/SspA and FevR (PigR) interactions in Francisella. Production of ppGpp is commonly known to be activated by cellular and nutritional stress in bacteria, which indicates that cellular and nutritional stresses act as important signals for FPI activation. In this work, we demonstrate that mutations in migR, trmE, or cphA significantly reduce ppGpp accumulation. The reduction in ppGpp levels was similar for each of the mutants and correlated with a corresponding reduction in iglA reporter expression. In addition, we observed that there were differences in the ability of each of these mutants to replicate within various mammalian cells, indicating that the migR, trmE, and cphA genes are likely parts of different cellular stress response pathways in Francisella. These results also indicate that different nutritional and cellular stresses exist in different mammalian cells. This work provides new information to help understand how Francisella regulates its virulence genes in response to host cell environments, and it contributes to our growing knowledge of this highly successful bacterial pathogen. PMID:23716606

Faron, Matthew; Fletcher, Joshua R.; Rasmussen, Jed A.; Long, Matthew E.; Allen, Lee-Ann H.

2013-01-01

109

The Francisella tularensis migR, trmE, and cphA genes contribute to F. tularensis pathogenicity island gene regulation and intracellular growth by modulation of the stress alarmone ppGpp.  

PubMed

The Francisella tularensis pathogenicity island (FPI) encodes many proteins that are required for virulence. Expression of these genes depends upon the FevR (PigR) regulator and its interactions with the MglA/SspA and RNA polymerase transcriptional complex. Experiments to identify how transcription of the FPI genes is activated have led to identification of mutations within the migR, trmE, and cphA genes that decrease FPI expression. Recent data demonstrated that the small alarmone ppGpp, produced by RelA and SpoT, is important for stabilizing MglA/SspA and FevR (PigR) interactions in Francisella. Production of ppGpp is commonly known to be activated by cellular and nutritional stress in bacteria, which indicates that cellular and nutritional stresses act as important signals for FPI activation. In this work, we demonstrate that mutations in migR, trmE, or cphA significantly reduce ppGpp accumulation. The reduction in ppGpp levels was similar for each of the mutants and correlated with a corresponding reduction in iglA reporter expression. In addition, we observed that there were differences in the ability of each of these mutants to replicate within various mammalian cells, indicating that the migR, trmE, and cphA genes are likely parts of different cellular stress response pathways in Francisella. These results also indicate that different nutritional and cellular stresses exist in different mammalian cells. This work provides new information to help understand how Francisella regulates its virulence genes in response to host cell environments, and it contributes to our growing knowledge of this highly successful bacterial pathogen. PMID:23716606

Faron, Matthew; Fletcher, Joshua R; Rasmussen, Jed A; Long, Matthew E; Allen, Lee-Ann H; Jones, Bradley D

2013-08-01

110

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

SciTech Connect

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.

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

111

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

PubMed Central

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

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

112

Speaking up: a moral obligation.  

PubMed

As we rush around attending to the essentials of our lives (family, friends, clients, employers), what is left? Nursing Forum invites readers to engage in thoughts and activities that may awaken an untouched place. We hope these writings will kindle your personal involvement in something that was previously avoided--because of bias, fear, or uneasiness--in order to stretch your mind and spirit. The purpose of this paper is to explore the act of speaking up as a moral obligation and its relationship to moral courage and habit. The difficulties of speaking up and the consequences of silence are examined. The benefits of speaking up are raising self-respect, gaining courage, forming good habits and passing on that legacy. PMID:8716884

Kelly, B

1996-01-01

113

5 CFR 724.404 - Agency obligations.  

Code of Federal Regulations, 2010 CFR

...IMPLEMENTATION OF TITLE II OF THE NOTIFICATION AND FEDERAL EMPLOYEE ANTIDISCRIMINATION AND RETALIATION ACT OF 2002 Best Practices § 724.404 Agency obligations. (a) Within 30 working days of issuance of the advisory guidelines...

2010-01-01

114

21 CFR 26.62 - General obligations.  

Code of Federal Regulations, 2010 CFR

...MEDICAL DEVICE PRODUCT EVALUATION REPORTS: UNITED STATES AND THE EUROPEAN COMMUNITY âFrameworkâ Provisions § 26.62 General obligations...assessment bodies (CAB's) and/or authorities. (b) The European Community (EC) and its Member States shall, as...

2010-04-01

115

7 CFR 989.37 - Obligation.  

Code of Federal Regulations, 2011 CFR

...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....

2011-01-01

116

Federal Academic Science and Engineering Obligations Decreased  

NSF Publications Database

... Obligations Decreased Slightly in FY 1996 (April 27, 1998) This data brief highlights the major ... Fiscal Year 1996. A full set of Detailed Statistical Tables covering FY 1996 and prior years will be ...

117

19 CFR 10.865 - Importer obligations.  

Code of Federal Regulations, 2012 CFR

...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Oman Free Trade Agreement Import Requirements § 10.865 Importer obligations. (a) General. An importer who makes...

2012-04-01

118

19 CFR 10.865 - Importer obligations.  

Code of Federal Regulations, 2011 CFR

...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Oman Free Trade Agreement Import Requirements § 10.865 Importer obligations. (a) General. An importer who makes...

2011-04-01

119

19 CFR 10.865 - Importer obligations.  

Code of Federal Regulations, 2013 CFR

...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Oman Free Trade Agreement Import Requirements § 10.865 Importer obligations. (a) General. An importer who makes...

2013-04-01

120

19 CFR 10.865 - Importer obligations.  

...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Oman Free Trade Agreement Import Requirements § 10.865 Importer obligations. (a) General. An importer who makes...

2014-04-01

121

Naval Engineering A National Naval Obligation  

E-print Network

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 ...

Chryssostomidis, Chryssostomos

2000-05-16

122

46 CFR Sec. 11 - Guarantee obligations.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

123

5 CFR 352.908 - Agency obligation.  

Code of Federal Regulations, 2010 CFR

...OFFICE 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...

2010-01-01

124

Obligate symbionts activate immune system development in the tsetse fly  

PubMed Central

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 3 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 (GmmApo) 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 non-pathogenic E. coli. The susceptible phenotype exhibited by GmmApo 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 GmmApo larvae when their moms 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 it's host. PMID:22368278

Weiss, Brian L.; Maltz, Michele; Aksoy, Serap

2012-01-01

125

Plasmodiophorids: The Challenge to Understand Soil-Borne, Obligate Biotrophs with a Multiphasic Life Cycle  

Microsoft Academic Search

\\u000a Plasmodiophorids are an enigmatic group of obligate biotrophic pathogens of higher plants. Together with their sister group\\u000a phagomyxids, which infect stramenopiles, they form the monophyletic eukaryote clade phytomyxids. They have long been treated\\u000a as a basal group of fungi, but recent molecular phylogenies point to a close affiliation with the protozoan phylum Cercozoa.\\u000a The soil-borne and plant-associated nature of plasmodiophorids

Sigrid Neuhauser; Simon Bulman; Martin Kirchmair

126

Microsporidia Are Natural Intracellular Parasites of the Nematode Caenorhabditis elegans  

PubMed Central

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

Troemel, Emily R; Felix, Marie-Anne; Whiteman, Noah K; Barriere, Antoine; Ausubel, Frederick M

2008-01-01

127

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

PubMed

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

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

2014-10-01

128

Microsporidia Are Natural Intracellular Parasites of the Nematode Caenorhabditis  

E-print Network

Microsporidia Are Natural Intracellular Parasites of the Nematode Caenorhabditis elegans Emily R, United States of America For decades the soil nematode Caenorhabditis elegans has been an important model infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells

Ausubel, Frederick M.

129

Antimicrobial susceptibility and molecular characterization of Mycobacterium intracellulare in China.  

PubMed

Mycobacterium avium complex (MAC) is the most common non-tuberculosis mycobacterial pathogen isolated from respiratory samples, mainly including two species, Mycobacterium avium (M. avium) and Mycobacterium intracellulare (M. intracellulare). Although these two species belong to the same group, M. avium and M. intracellulare reveal significantly differences in pathogenicity and biology. Nevertheless, little is known regarding the drug resistant details profile of M. avium or M. intracellulare instead of MAC. Here, we examined the antimicrobial susceptibility profiles of 52 clinical M. intracellulare isolates against fourteen antimicrobial agents, which are widely selected for the treatment of nontuberculous mycobacteria (NTM) infection. The drug susceptibility test revealed that clarithromycin (47/52, 90.4%), rifampicin (41/52, 78.8%) and capreomycin (40/52, 76.9%) revealed highly antimicrobial activities against M. intracellulare isolates in vitro. Furthermore, all clarithromycin resistant isolates harbored mutations in the 23S rRNA gene, and the percentage of amikacin resistant ones with mutation in the rrs gene is 62.5% (10/16). The Hunter-Gaston Discriminatory Index (HGDI) value for the 16-loci Variable Number of Tandem Repeat (VNTR) typing of M. intracellulare isolates was 0.994, and M. intracellulare resistance to moxifloxacin was significantly more commonly found in clustered strains than in nonclustered strains (?(2)=5.551, P=0.040). In conclusion, our data demonstrated that clarithromycin and capreomycin revealed highly antimicrobial activities against M. intracellulare isolates, and clarithromycin and amikacin resistance could be detected more readily and rapidly using molecular scanning of corresponding drug target than conventional drug susceptibility testing. We also found that infection by clustered strains was significantly associated with resistance to moxifloxacin. PMID:25131955

Zhao, Xiuqin; Wang, Yufeng; Pang, Yu

2014-10-01

130

Intracellular antibody immunity.  

PubMed

Antibodies allow the immune system to target pathogens despite their tremendous diversity and rapid evolution. Once bound to a pathogen, antibodies induce a broad range of effector mechanisms, including phagocytosis and complement. However, these mechanisms are all initiated in the extracellular space, meaning that pathogens like viruses evade them upon infection of their target cells. Recently, it has been shown that, in addition to mediating extracellular immune responses, antibodies also activate immunity inside infected cells. Antibodies that are bound to the surface of non-enveloped viruses or bacteria are carried into the cell during pathogen entry. Once inside the cell, these pathogen-attached antibodies are recognised by a highly conserved, high affinity cytosolic antibody receptor called TRIM21. TRIM21 initiates both sensor and effector responses that reduce viral replication and induce an antiviral state. These responses are an important part of antiviral immunity and the removal of TRIM21 results in uncontrolled viraemia and death in a mouse model of infection. PMID:24722852

Watkinson, Ruth E; McEwan, William A; James, Leo C

2014-07-01

131

Identification of cytoplasmic membrane protein antigens of Mycobacterium avium, M. intracellulare, and M. scrofulaceum  

E-print Network

where these slow-growing pathogenic bacteria have been isolated (Brookset al. 1984; Falkinhamet al. 1980Identification of cytoplasmic membrane protein antigens of Mycobacterium avium, M. intracellulare. intracellulare, and M. scrofulaceum. Can. J. Microbiol. 35: 529-534. The cytoplasmic membrane isolated from

Falkinham, Joseph

132

Apoptosis paves the detour path for CD8 T cell activation against intracellular bacteria  

Microsoft Academic Search

Summary Intracellular bacteria such as Mycobacterium tubercu- losis primarily infect macrophages. Within these host cells, the pathogens are confined to phagosomes and their antigens are secluded from the classical MHC I presentation pathway. Moreover, macrophages fail to express certain antigen presenting molecules like CD1 proteins. As a result of this intracellular lifestyle, the pathways for the induction of MHC I-

Florian Winau; Stefan H. E. Kaufmann; Ulrich E. Schaible

2004-01-01

133

Patients' ethical obligation for their health.  

PubMed Central

In contemporary medical ethics health is rarely acknowledged to be an ethical obligation. This oversight is due to the preoccupation of most bioethicists with a rationalist, contract model for ethics in which moral obligation is limited to truth-telling and promise-keeping. Such an ethics is poorly suited to medicine because it fails to appreciate that medicine's basis as a moral enterprise is oriented towards health values. A naturalistic model for medical ethics is proposed which builds upon biological and medical values. This perspective clarifies ethical obligations to ourselves and to others for life and health. It provides a normative framework for the doctor-patient relationship within which to formulate medical advice and by which to evaluate patient choice. PMID:6502640

Sider, R C; Clements, C D

1984-01-01

134

Cell Host & Microbe Autophagy Induction by the Pathogen Receptor CD46  

E-print Network

Cell Host & Microbe Article Autophagy Induction by the Pathogen Receptor CD46 Pierre.09.006 SUMMARY Autophagy is a highly regulated self-degradative mechanism required at a basal level for intracellular clearance and recycling of cytoplasmic contents. Upon intracellular pathogen invasion, autophagy

135

Intervention of Phytohormone Pathways by Pathogen Effectors[OPEN  

PubMed Central

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

Kazan, Kemal; Lyons, Rebecca

2014-01-01

136

Benefit Finding and Perceived Obligations of Victims  

E-print Network

of abuse and thought about the lesson of victimization for the perpetrator or the victim. Participants perceived the victim as more obligated to help and to not do harm when focused on the victim as compared to the perpetrator, to the extent...

Warner, Ruth

2007-12-11

137

Higher Education's Cultural Obligations: Views and Reviews.  

ERIC Educational Resources Information Center

Perspectives on the cultural obligations of higher education are presented in this collection of papers. Higher education's possible and probable cultural function is addressed from the perspective of business, the arts, education, and religion. Also discussed is the role of institutions of higher education in establishing a system of values,…

Reid, John Y., Ed.

138

Fetal Diagnosis – Obligations of the Clinician  

Microsoft Academic Search

Fetal echocardiography allows for accurate diagnosis of major heart abnormalities by 16–18 weeks. The parents have up to 22 weeks to consider possible termination. What are the obligations of the clinician once an abnormality is found? Should only information be provided or is there a role in influencing the parents’ decision? Two diverse examples are provided to discuss these questions.

Samuel Menahem; Lynn Gillam

2007-01-01

139

Resistance to Bacterial Pathogens in Plants  

E-print Network

(yellowing). For example, wilt-causing bacteria clog the vascular tissue, preventing movement of water-surface-based surveillance system that detects conserved pathogen molecules and (3) an intracellular surveillance system system, plants have to rely solely on their innate immune system to defend themselves against invading

Innes, Roger

140

Invasion and Intracellular Survival by Protozoan Parasites  

PubMed Central

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

Sibley, L. David

2013-01-01

141

LOW PATHOGENIC POTENTIAL IN HETEROTROPHIC BACTERIA FROM POTABLE WATER  

EPA Science Inventory

Forty-five isolates of HPC bacteria, most of which express virulence-related characteristics are being tested for pathogenicity in immunocompromised mice. All forty-five were negative for facultative intracellular pathogenicity. All twenty-three isolates tested thus far were a...

142

Pathogen–endoplasmic-reticulum interactions: in through the out door  

Microsoft Academic Search

A key determinant for the survival of intracellular pathogens is their ability to subvert the cellular processes of the host to establish a compartment that allows replication. Although most microorganisms internalized by host cells are efficiently cleared following fusion with lysosomes, many pathogens have evolved mechanisms to escape this degradation. In this Review, we provide insight into the molecular processes

Craig R. Roy; Suzana P. Salcedo; Jean-Pierre E. Gorvel

2006-01-01

143

28 CFR 811.3 - Notice of obligation to register.  

Code of Federal Regulations, 2012 CFR

...AGENCY FOR THE DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.3 Notice of obligation to register. (a) Sex offenders may be notified of their obligation...See sections 4, 6 and 8 of the Sex Offender Registration Act of...

2012-07-01

144

28 CFR 811.3 - Notice of obligation to register.  

Code of Federal Regulations, 2011 CFR

...AGENCY FOR THE DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.3 Notice of obligation to register. (a) Sex offenders may be notified of their obligation...See sections 4, 6 and 8 of the Sex Offender Registration Act of...

2011-07-01

145

28 CFR 811.3 - Notice of obligation to register.  

Code of Federal Regulations, 2013 CFR

...AGENCY FOR THE DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.3 Notice of obligation to register. (a) Sex offenders may be notified of their obligation...See sections 4, 6 and 8 of the Sex Offender Registration Act of...

2013-07-01

146

12 CFR 966.2 - Issuance of consolidated obligations.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

147

12 CFR 966.2 - Issuance of consolidated obligations.  

Code of Federal Regulations, 2010 CFR

...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...

2010-01-01

148

28 CFR 42.307 - Obligations of recipients.  

...2014-07-01 false Obligations of recipients. 42.307 Section 42.307 Judicial Administration DEPARTMENT OF JUSTICE... Equal Employment Opportunity Program Guidelines § 42.307 Obligations of recipients. The...

2014-07-01

149

24 CFR 291.565 - Continuing obligations after purchase.  

Code of Federal Regulations, 2010 CFR

... false Continuing obligations after purchase. 291.565 Section 291.565 Housing...HUD-ACQUIRED SINGLE FAMILY PROPERTY Good Neighbor Next Door Sales Program § 291.565 Continuing obligations after purchase. To remain in compliance with...

2010-04-01

150

23 CFR 230.205 - Supportive services funds obligation.  

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS EXTERNAL PROGRAMS Supportive Services for Minority, Disadvantaged, and Women Business Enterprises § 230.205 Supportive services funds obligation. Supportive services funds shall be obligated...

2014-04-01

151

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

E-print Network

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...

Nam, Mi Young

2004-11-15

152

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2011 CFR

...subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage obligations for the payment of both straight...contractor or subcontractor may discharge his minimum wage obligations for the payment of straight...

2011-07-01

153

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2012 CFR

...subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage obligations for the payment of both straight...contractor or subcontractor may discharge his minimum wage obligations for the payment of straight...

2012-07-01

154

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2013 CFR

...subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage obligations for the payment of both straight...contractor or subcontractor may discharge his minimum wage obligations for the payment of straight...

2013-07-01

155

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2010 CFR

...subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage obligations for the payment of both straight...contractor or subcontractor may discharge his minimum wage obligations for the payment of straight...

2010-07-01

156

29 CFR 5.31 - Meeting wage determination obligations.  

...subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage obligations for the payment of both straight...contractor or subcontractor may discharge his minimum wage obligations for the payment of straight...

2014-07-01

157

16 CFR 436.2 - Obligation to furnish documents.  

Code of Federal Regulations, 2010 CFR

...Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES DISCLOSURE REQUIREMENTS AND PROHIBITIONS CONCERNING FRANCHISING Franchisors' Obligations § 436.2 Obligation to furnish documents. In connection with the offer or...

2010-01-01

158

12 CFR 560.42 - State and local government obligations.  

Code of Federal Regulations, 2010 CFR

...Federal Savings Associations § 560.42 State and local government obligations. (a) What limitations apply? Pursuant to HOLA section 5(c)(1)(H), a Federal savings association (“you”) may invest in obligations issued by any state,...

2010-01-01

159

29 CFR 4043.20 - Post-Event filing obligation.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 2011-07-01 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...

2011-07-01

160

29 CFR 4043.20 - Post-Event filing obligation.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 2012-07-01 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...

2012-07-01

161

29 CFR 4043.20 - Post-Event filing obligation.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 2013-07-01 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...

2013-07-01

162

29 CFR 4043.20 - Post-Event filing obligation.  

Code of Federal Regulations, 2010 CFR

... 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...

2010-07-01

163

Exploring Anti-Bacterial Compounds against Intracellular Legionella  

PubMed Central

Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation. The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. Thus, L. pneumophila can act as an ‘accidental’ human pathogen and cause a severe pneumonia known as Legionnaires’ disease. The intracellular localisation of L. pneumophila protects it from some antibiotics, and this fact must be taken into account to develop new anti-bacterial compounds. In addition, the intracellular lifestyle of L. pneumophila may render the bacteria susceptible to compounds diminishing bacterial virulence and decreasing intracellular survival and replication of this pathogen. The development of a single infection cycle intracellular replication assay using GFP-producing L. pneumophila and Acanthamoebacastellanii amoeba is reported here. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. pneumophila replication, several known host-targeting compounds were tested, including modulators of cytoskeletal dynamics, vesicle scission and Ras GTPase localisation. Our results reveal a hitherto unrealized potential antibiotic property of the ?-lactone-based Ras depalmitoylation inhibitor palmostatin M, but not the closely related inhibitor palmostatin B. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target. PMID:24058631

Harrison, Christopher F.; Kicka, Sebastien; Trofimov, Valentin; Berschl, Kathrin; Ouertatani-Sakouhi, Hajer; Ackermann, Nikolaus; Hedberg, Christian; Cosson, Pierre; Soldati, Thierry; Hilbi, Hubert

2013-01-01

164

Nanovehicular Intracellular Delivery Systems  

PubMed Central

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

PROKOP, ALES; DAVIDSON, JEFFREY M.

2013-01-01

165

Ultrastructural Changes in an Obligately Barophilic Marine Bacterium after Decompression  

PubMed Central

The bacterial isolate MT-41 from 10,476 m, nearly the greatest ocean depth, is obligately barophilic. The purpose of this study was to describe the morphological changes in MT-41 due to nearly isothermal decompression followed by incubation at atmospheric pressure. Two cultures were grown at 103.5 MPa and 2°C and then decompressed to atmospheric pressure (0.101 MPa). One of the cultures was fixed just before decompression. The other culture, kept at 0°C, was sampled immediately and four more times over 168 h. The number of CFU (assayed at 103.5 MPa and 2°C) declined with incubation time at atmospheric pressure. Decompression itself did not lead to immediate morphological changes. The ultrastructure, however, was altered with increasing time at atmospheric pressure. The first aberrations were intracellular vesicles and membrane fragments in the medium. After these changes were plasmolysis, cell lysis, the formation of extracellular vesicles, and the formation of ghost cells. Intact cells in the longest incubation at atmospheric pressure had the normal cytoplasmic granularity suggestive of ribosomes but had few and poorly stained fibrils in the bacterial nucleoids. From the practical standpoint, samples of hadal deep-sea regions need to be fixed either in situ or shortly after arrival at the sea surface even when recovered in insulated sampling gear. This should prevent drastic structural degradation of sampled cells, thus allowing both accurate estimates of deep-sea benthic standing stock and realistic morphological descriptions. Images PMID:16348489

Chastain, Roger A.; Yayanos, A. Aristides

1991-01-01

166

Experimental evolution of nodule intracellular infection in legume symbionts  

PubMed Central

Soil bacteria known as rhizobia are able to establish an endosymbiosis with legumes that takes place in neoformed nodules in which intracellularly hosted bacteria fix nitrogen. Intracellular accommodation that facilitates nutrient exchange between the two partners and protects bacteria from plant defense reactions has been a major evolutionary step towards mutualism. Yet the forces that drove the selection of the late event of intracellular infection during rhizobium evolution are unknown. To address this question, we took advantage of the previous conversion of the plant pathogen Ralstonia solanacearum into a legume-nodulating bacterium that infected nodules only extracellularly. We experimentally evolved this draft rhizobium into intracellular endosymbionts using serial cycles of legume-bacterium cocultures. The three derived lineages rapidly gained intracellular infection capacity, revealing that the legume is a highly selective environment for the evolution of this trait. From genome resequencing, we identified in each lineage a mutation responsible for the extracellular–intracellular transition. All three mutations target virulence regulators, strongly suggesting that several virulence-associated functions interfere with intracellular infection. We provide evidence that the adaptive mutations were selected for their positive effect on nodulation. Moreover, we showed that inactivation of the type three secretion system of R. solanacearum that initially allowed the ancestral draft rhizobium to nodulate, was also required to permit intracellular infection, suggesting a similar checkpoint for bacterial invasion at the early nodulation/root infection and late nodule cell entry levels. We discuss our findings with respect to the spread and maintenance of intracellular infection in rhizobial lineages during evolutionary times. PMID:23426010

Guan, Su Hua; Gris, Carine; Cruveiller, Stephane; Pouzet, Cecile; Tasse, Lena; Leru, Aurelie; Maillard, Aline; Medigue, Claudine; Batut, Jacques; Masson-Boivin, Catherine; Capela, Delphine

2013-01-01

167

A new role of the complement system: C3 provides protection in a mouse model of lung infection with intracellular Chlamydia psittaci.  

PubMed

The complement system modulates the intensity of innate and specific immunity. While it protects against infections by extracellular bacteria its role in infection with obligate intracellular bacteria, such as the avian and human pathogen Chlamydia (C.) psittaci, is still unknown. In the present study, knockout mice lacking C3 and thus all main complement effector functions were intranasally infected with C. psittaci strain DC15. Clinical parameters, lung histology, and cytokine levels were determined. A subset of infections was additionally performed with mice lacking C5 or C5a receptors. Complement activation occurred before symptoms of pneumonia appeared. Mice lacking C3 were ?100 times more susceptible to the intracellular bacteria compared to wild-type mice, with all C3(-/-) mice succumbing to infection after day 9. At a low infective dose, C3(-/-) mice became severely ill after an even longer delay, the kinetics suggesting a so far unknown link of complement to the adaptive, protective immune response against chlamydiae. The lethal phenotype of C3(-/-) mice is not based on differences in the anti-chlamydial IgG response (which is slightly delayed) as demonstrated by serum transfer experiments. In addition, during the first week of infection, the absence of C3 was associated with partial protection characterized by reduced weight loss, better clinical score and lower bacterial burden, which might be explained by a different mechanism. Lack of complement functions downstream of C5 had little effect. This study demonstrates for the first time a strong and complex influence of complement effector functions, downstream of C3 and upstream of C5, on the outcome of an infection with intracellular bacteria, such as C. psittaci. PMID:23189195

Bode, Jenny; Dutow, Pavel; Sommer, Kirsten; Janik, Katrin; Glage, Silke; Tümmler, Burkhard; Munder, Antje; Laudeley, Robert; Sachse, Konrad W; Klos, Andreas

2012-01-01

168

26 CFR 1.691(e)-1 - Installment obligations transmitted at death when prior law applied.  

... Installment obligations transmitted at death when prior law applied. 1.691(e... Installment obligations transmitted at death when prior law applied. (a) In general...transmission of installment obligations at the death of a holder of such obligations were...

2014-04-01

169

Cationic antimicrobial peptide LL-37 is effective against both extra- and intracellular Staphylococcus aureus.  

PubMed

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

Noore, Jabeen; Noore, Adly; Li, Bingyun

2013-03-01

170

Antimicrobial responses of teleost phagocytes and innate immune evasion strategies of intracellular bacteria.  

PubMed

During infection, macrophage lineage cells eliminate infiltrating pathogens through a battery of antimicrobial responses, where the efficacy of these innate immune responses is pivotal to immunological outcomes. Not surprisingly, many intracellular pathogens have evolved mechanisms to overcome macrophage defenses, using these immune cells as residences and dissemination strategies. With pathogenic infections causing increasing detriments to both aquacultural and wild fish populations, it is imperative to garner greater understanding of fish phagocyte antimicrobial responses and the mechanisms by which aquatic pathogens are able to overcome these teleost macrophage barriers. Insights into the regulation of macrophage immunity of bony fish species will lend to the development of more effective aquacultural prophylaxis as well as broadening our understanding of the evolution of these immune processes. Accordingly, this review focuses on recent advances in the understanding of teleost macrophage antimicrobial responses and the strategies by which intracellular fish pathogens are able to avoid being killed by phagocytes, with a focus on Mycobacterium marinum. PMID:23954721

Grayfer, Leon; Hodgkinson, Jordan W; Belosevic, Miodrag

2014-04-01

171

Intracellular microbes and haemophagocytosis.  

PubMed

Haemophagocytosis (hemophagocytosis) is the phenomenon of activated macrophage consumption of red and white blood cells, including professional phagocytes and lymphocytes. It can occur in patients with severe cases of intracellular microbial infection, including avian influenza, leishmaniasis, tuberculosis and typhoid fever. While well-known to physicians since at least the mid-1800s, haemophagocytosis has been little studied due to a paucity of tractable animal and cell culture models. Recently, haemophagocytosis has been described in a mouse model of typhoid fever, and it was noted that the infectious agent, Salmonella enterica, resides within haemophagocytic macrophages in mice. In addition, a cell culture model for haemophagocytosis revealed that S. enterica preferentially replicate in haemophagocytic macrophages. This review describes how, at the molecular and cellular levels, S. enterica may promote and take advantage of haemophagocytosis to establish long-term systemic infections in mammals. The role, relevance and possible molecular mechanisms of haemophagocytosis are discussed within the context of other microbial infections and of genetic deficiencies in which haemophagocytosis occurs and is associated with morbidity. PMID:18616693

Silva-Herzog, Eugenia; Detweiler, Corrella S

2008-11-01

172

Metabolism of the vacuolar pathogen Legionella and implications for virulence  

PubMed Central

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

Manske, Christian; Hilbi, Hubert

2014-01-01

173

Rapid Identification and Detection of Intracellular Survival Testing of Mycobacterium smegmatis mc 2 155 that Contains eis Gene from Mycobacterium tuberculosis by Flow Cytometry  

Microsoft Academic Search

Mycobacterium tuberculosis is a facultative intracellular pathogen that has evolved the ability to survive and multiply within human macrophages. The\\u000a enhanced intracellular survival (eis) gene (Rv2416c) from M. tuberculosis has been identified as a potential factor that can enhance the intracellular survival of Mycobacterium smegmatis in the macrophage cell line. However, the time requirements for intracellular survival testing of Mycobacterium

Zichun He; Shengjin Li; Xiangdong Zhou

174

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

NSDL National Science Digital Library

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.

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

2008-04-29

175

"Obligated aliens": recognizing sperm donors' ethical obligation to disclose genetic information.  

PubMed

Sperm donors' obligations are typically constrained to the immediate circumstances surrounding the donation and to its time frame. This paper makes the case for recognizing an ongoing ethical obligation that binds sperm donors to disclose, in a timely manner, meaningful genetic information to recipients and donor-conceived children. The paper delineates and conceptualizes the suggested (potentially reciprocal) duty and argues that it is not the genetic link between the donor and the donor-conceived child that binds donors by said duty, but rather social responsibility. Accordingly, an original perception of the donor as an obligated alien is suggested and developed. The main thesis of the paper is supported inter alia by a comparison between transmitting infectious diseases and passing faulty genes on to donor-conceived children. The paper also provides an in-depth analysis of the conflicting interests of the parties generated by such an obligation and proposes a model for embedding this ethical duty in a (legal) contractual framework. PMID:23678628

Tamir, Sivan

2013-03-01

176

Is there a moral obligation not to infect others?  

PubMed

The emergence of HIV infection and AIDS has refocused concern on the obligations surrounding the carrying and transmission of communicable diseases. This article asks three related questions: Is there a general duty not to spread contagion? Are there special obligations not to communicate disease in the workplace? And does the mode of transmission of the disease affect the ethics of transmission and, if so, how and to what extent? There seems to be a strong prima facie obligation not to harm others by making them ill where this is avoidable, and this obligation not to communicate disease applies as much to relatively trivial diseases like the common cold as it does to HIV disease. The reasonableness of expecting people to live up to this obligation, however, depends on society reciprocating the obligation in the form of providing protection and compensation. PMID:7488907

Harris, J; Holm, S

1995-11-01

177

Obligately barophilic bacterium from the Mariana trench.  

PubMed

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. PMID:6946468

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

1981-08-01

178

7 CFR 1450.105 - Obligations of participant.  

Code of Federal Regulations, 2012 CFR

...Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOMASS CROP ASSISTANCE PROGRAM (BCAP) Matching Payments § 1450.105 Obligations of participant. (a) All...

2012-01-01

179

7 CFR 1450.105 - Obligations of participant.  

Code of Federal Regulations, 2011 CFR

...Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOMASS CROP ASSISTANCE PROGRAM (BCAP) Matching Payments § 1450.105 Obligations of participant. (a) All...

2011-01-01

180

7 CFR 1450.105 - Obligations of participant.  

Code of Federal Regulations, 2013 CFR

...Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOMASS CROP ASSISTANCE PROGRAM (BCAP) Matching Payments § 1450.105 Obligations of participant. (a) All...

2013-01-01

181

7 CFR 1450.105 - Obligations of participant.  

...Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOMASS CROP ASSISTANCE PROGRAM (BCAP) Matching Payments § 1450.105 Obligations of participant. (a) All...

2014-01-01

182

Prison Break: Pathogens' Strategies To Egress from Host Cells  

PubMed Central

Summary: A wide spectrum of pathogenic bacteria and protozoa has adapted to an intracellular life-style, which presents several advantages, including accessibility to host cell metabolites and protection from the host immune system. Intracellular pathogens have developed strategies to enter and exit their host cells while optimizing survival and replication, progression through the life cycle, and transmission. Over the last decades, research has focused primarily on entry, while the exit process has suffered from neglect. However, pathogen exit is of fundamental importance because of its intimate association with dissemination, transmission, and inflammation. Hence, to fully understand virulence mechanisms of intracellular pathogens at cellular and systemic levels, it is essential to consider exit mechanisms to be a key step in infection. Exit from the host cell was initially viewed as a passive process, driven mainly by physical stress as a consequence of the explosive replication of the pathogen. It is now recognized as a complex, strategic process termed “egress,” which is just as well orchestrated and temporally defined as entry into the host and relies on a dynamic interplay between host and pathogen factors. This review compares egress strategies of bacteria, pathogenic yeast, and kinetoplastid and apicomplexan parasites. Emphasis is given to recent advances in the biology of egress in mycobacteria and apicomplexans. PMID:23204363

Friedrich, Nikolas; Hagedorn, Monica; Soldati-Favre, Dominique

2012-01-01

183

Genetic ignorance, moral obligations and social duties.  

PubMed

In a contribution to The Journal of Medicine and Philosophy, Professor Rosamond Rhodes argues that individuals sometimes have an obligation to know about their genetic disorders, because this is required by their status as autonomous persons. Her analysis, which is based on Kant's concept of autonomy and Aristotle's notion of friendship, is extended here to consequentialist concerns. These are of paramount importance if, as we believe and Professor Rhodes herself implies, the Kantian and Aristotelian doctrines can be helpful only in the sphere of private morality, not in the public realm. Better tools for assessing the right to genetic ignorance as an issue of public policy can, we contend, be found in Mill's ideas concerning liberty and the prevention of harm. Our own conclusion, based on the Millian way of thinking, is that individuals probably do have the right to remain in ignorance in the cases Professor Rhodes presents as examples of a duty to know. PMID:10732878

Takala, T; Häyry, M

2000-02-01

184

Ethical theory, "common morality," and professional obligations.  

PubMed

We have two aims in this paper. The first is negative: to demonstrate the problems in Bernard Gert's account of common morality, in particular as it applies to professional morality. The second is positive: to suggest a more satisfactory explanation of the moral basis of professional role morality, albeit one that is broadly consistent with Gert's notion of common morality, but corrects and supplements Gert's theory. The paper is in three sections. In the first, we sketch the main features of Gert's account of common morality in general. In the second, we outline Gert's explanation of the source of professional moral rules and demonstrate its inadequacy. In the third section, we provide an account of our own collectivist needs-based view of the source of the role-moral obligations of many professional roles, including those of health care professionals. PMID:19199076

Alexandra, Andrew; Miller, Seumas

2009-01-01

185

[Facultative and obligate aerobic methylobacteria synthesize cytokinins].  

PubMed

The presence and expression of genes controlling the synthesis and secretion of cytokinins by the pink-pigmented facultative methylotroph Methylobacterium mesophilicum VKM B-2143 with the serine pathway and nonpigmented obligate methylotroph Methylovorus mays VKM B-2221 with the ribulose monophosphate pathway of C1 metabolism were shown using the polymerase chain reaction (PCR) and reverse transcription-PCR methods. The presence of the corresponding mRNA in M. mesophilicum cells grown on methanol or succinate suggests that the expression of these genes is constitutive. The cytokinin activity of culture liquid and its fractions was determined by a biotest with Amarantus caudatus L. seedlings. Using enzyme-linked immunosorbent analysis, we detected zeatin (riboside) in the culture liquid of both bacteria studied. The data obtained show that the aerobic methylobacteria are phytosymbionts that are able to utilize the single- and polycarbon compounds secreted by symbiotic plants and to synthesize cytokinins. PMID:11195573

Ivanova, E G; Doronina, N V; Shepeliakovskaia, A O; Laman, A G; Brovko, F A; Trotsenko, Iu A

2000-01-01

186

Utilities` ``obligation to serve`` under deregulation  

SciTech Connect

The utility no longer has protected status, and the traditional franchise concept is under attack. Exclusive rights once conveyed to the utilities are being denied and not just in the area of gas sales. Exclusive rights once conveyed to utilities will be denied in more areas. State by state, the utilities` franchise is being examined to see which, if any, of its provisions are necessary in a deregulated environment. Can the free market provide everything that`s been provided for many years under monopolistic arrangements? Some of the most critical and difficult of these provisions concern the obligation to serve, which utilities, in most states, have assumed as part of their franchise agreement. Regulators, courts, utilities, marketers and others are busy sorting through these issues, but resolution could take years. The paper discusses deregulation, universal service fee, representation without taxation, suppliers and marketer restrictions.

Alexander, C.B.

1997-02-01

187

The Role Obligations of Students and Lecturers in Higher Education  

ERIC Educational Resources Information Center

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

Regan, Julie-Anne

2012-01-01

188

Schooling properties of an obligate and a facultative fish species  

E-print Network

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

Paris-Sud XI, Université de

189

The Evolutionary Pathway to Obligate Scavenging in Gyps Vultures  

Microsoft Academic Search

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

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

2011-01-01

190

Deconfounding Distance Effects in Judgments of Moral Obligation  

ERIC Educational Resources Information Center

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…

Nagel, Jonas; Waldmann, Michael R.

2013-01-01

191

Molecular basis of host specificity in human pathogenic bacteria  

PubMed Central

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.

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

2014-01-01

192

Metallochaperones regulate intracellular copper levels.  

PubMed

Copper (Cu) is an important enzyme co-factor that is also extremely toxic at high intracellular concentrations, making active efflux mechanisms essential for preventing Cu accumulation. Here, we have investigated the mechanistic role of metallochaperones in regulating Cu efflux. We have constructed a computational model of Cu trafficking and efflux based on systems analysis of the Cu stress response of Halobacterium salinarum. We have validated several model predictions via assays of transcriptional dynamics and intracellular Cu levels, discovering a completely novel function for metallochaperones. We demonstrate that in addition to trafficking Cu ions, metallochaperones also function as buffers to modulate the transcriptional responsiveness and efficacy of Cu efflux. This buffering function of metallochaperones ultimately sets the upper limit for intracellular Cu levels and provides a mechanistic explanation for previously observed Cu metallochaperone mutation phenotypes. PMID:23349626

Pang, W Lee; Kaur, Amardeep; Ratushny, Alexander V; Cvetkovic, Aleksandar; Kumar, Sunil; Pan, Min; Arkin, Adam P; Aitchison, John D; Adams, Michael W W; Baliga, Nitin S

2013-01-01

193

Metallochaperones Regulate Intracellular Copper Levels  

PubMed Central

Copper (Cu) is an important enzyme co-factor that is also extremely toxic at high intracellular concentrations, making active efflux mechanisms essential for preventing Cu accumulation. Here, we have investigated the mechanistic role of metallochaperones in regulating Cu efflux. We have constructed a computational model of Cu trafficking and efflux based on systems analysis of the Cu stress response of Halobacterium salinarum. We have validated several model predictions via assays of transcriptional dynamics and intracellular Cu levels, discovering a completely novel function for metallochaperones. We demonstrate that in addition to trafficking Cu ions, metallochaperones also function as buffers to modulate the transcriptional responsiveness and efficacy of Cu efflux. This buffering function of metallochaperones ultimately sets the upper limit for intracellular Cu levels and provides a mechanistic explanation for previously observed Cu metallochaperone mutation phenotypes. PMID:23349626

Pang, W. Lee; Kaur, Amardeep; Ratushny, Alexander V.; Cvetkovic, Aleksandar; Kumar, Sunil; Pan, Min; Arkin, Adam P.; Aitchison, John D.; Adams, Michael W. W.; Baliga, Nitin S.

2013-01-01

194

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

Microsoft Academic Search

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

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

2009-01-01

195

60 FR 61700 - Schedule of Submission Dates for Statements of Net Outstanding Campaign Obligations Required from...  

Federal Register 2010, 2011, 2012, 2013

...Schedule of Submission Dates for Statements of Net Outstanding Campaign Obligations Required...Notice of submission dates for statements of net outstanding campaign obligations required...publishing submission dates for statements of net outstanding campaign obligations...

1995-12-01

196

20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.  

Code of Federal Regulations, 2010 CFR

...of obligations and duties of operator. 726...of obligations and duties of operator. Every obligation and duty in respect of payment...other treatment and care, the payment...operator by a district director,...

2010-04-01

197

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

PubMed Central

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

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

2014-01-01

198

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

PubMed

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

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

2014-05-01

199

Polyamines are implicated in the emergence of the embryo from obligate diapause.  

PubMed

Embryonic diapause is a poorly understood phenomenon of reversible arrest of embryo development prior to implantation. In many carnivores, such as the mink (Neovison vison), obligate diapause characterizes each gestation. Embryo reactivation is controlled by the uterus by mechanisms that remain elusive. Because polyamines are essential regulators of cell proliferation and growth, it was hypothesized that they trigger embryo reactivation. To test this, mated mink females were treated with ?-difluoromethylornithine, an inhibitor of ornithine decarboxylase 1, the rate-limiting enzyme in polyamine biosynthesis, or saline as a control during the first 5 d of reactivation. This treatment induced polyamine deprivation with the consequence of rearrest in embryo cell proliferation. A mink trophoblast cell line in vitro subjected to ?-difluoromethylornithine treatment likewise displayed an arrest in cell proliferation, morphological changes, and intracellular translocation of ornithine decarboxylase 1 protein. The arrest in embryo development deferred implantation for a period consistent with the length of treatment. Successful implantation and parturition ensued. We conclude that polyamine deprivation brought about a reversible rearrest of embryo development, which returned the mink embryo to diapause and induced a second delay in embryo implantation. The results are the first demonstration of a factor essential to reactivation of embryos in obligate diapause. PMID:21303959

Lefèvre, Pavine L C; Palin, Marie-France; Chen, Gary; Turecki, Gustavo; Murphy, Bruce D

2011-04-01

200

The Evolution of Genomic Instability in the Obligate Endosymbionts of Whiteflies  

PubMed Central

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

Sloan, Daniel B.; Moran, Nancy A.

2013-01-01

201

Intracellular proliferation of S. aureus in osteoblasts and effects of rifampicin and gentamicin on S. aureus intracellular proliferation and survival.  

PubMed

Staphylococcus aureus is the most clinically relevant pathogen regarding implant-associated bone infection and its capability to invade osteoblasts is well known. The aim of this study was to investigate firstly whether S. aureus is not only able to invade but also to proliferate within osteoblasts, secondly to delineate the mechanism of invasion and thirdly to clarify whether rifampicin or gentamicin can inhibit intracellular proliferation and survival of S. aureus. The SAOS-2 osteoblast-like cell line and human primary osteoblasts were infected with S. aureus EDCC5055 and S. aureus Rosenbach 1884. Both S. aureus strains were able to invade efficiently and to proliferate within human osteoblasts. Immunofluorescence microscopy showed intracellular invasion of S. aureus and transmission electron microscopy images could demonstrate bacterial division as a sign of intracellular proliferation as well as cytosolic bacterial persistence. Cytochalasin D, the major actin depolymerisation agent, was able to significantly reduce S. aureus invasion, suggesting that invasion was enabled by promoting actin rearrangement at the cell surface. 7.5 ?g/mL of rifampicin was able to inhibit bacterial survival in SAOS-2 cells with almost complete elimination of bacteria after 4 h. Gentamicin could also kill intracellular S. aureus in a dose-dependent manner, an effect that was significantly lower than that observed using rifampicin. In conclusion, S. aureus is not only able to invade but also to proliferate in osteoblasts. Invasion seems to be associated with actin rearrangement at the cell surface. Rifampicin is effective in intracellular eradication of S. aureus whereas gentamicin only poorly eliminates intracellularly replicating bacteria. PMID:25340805

Mohamed, W; Sommer, U; Sethi, S; Domann, E; Thormann, U; Schütz, I; Lips, K S; Chakraborty, T; Schnettler, R; Alt, V

2014-01-01

202

Host-pathogen diversity in a wild system: Chondrilla juncea – Puccinia chondrillina  

Microsoft Academic Search

The resistance structure of a Turkish population of the clonal, apomictic composite Chondrilla juncea and the pathotypic structure of a co-occurring population of its obligate rust pathogen, Puccinia chondrillina, was determined by sequential inoculation of 19 host lines with 15 pathogen isolates each derived from single pustules collected\\u000a from separate plants among the host population. The resultant matrix of resistant

C. Espiau; D. Riviere; J. J. Burdon; S. Gartner; B. Daclinat; S. Hasan; P. Chaboudez

1997-01-01

203

Immune responses to intracellular bacteria.  

PubMed

The multifaceted dialogue between intracellular bacteria and the mammalian host continues to be an exciting issue from both the scientific and public-health viewpoint. The recent year has witnessed some particularly impressive progress in knowledge about the two major culprits affecting the health of mankind, Mycobacterium tuberculosis and Salmonella typhi - the causative agents of tuberculosis and typhoid fever. PMID:11498297

Raupach, B; Kaufmann, S H

2001-08-01

204

Dynamics of intracellular information decoding  

Microsoft Academic Search

A variety of cellular functions are robust even to substantial intrinsic and extrinsic noise in intracellular reactions and the environment that could be strong enough to impair or limit them. In particular, of substantial importance is cellular decision-making in which a cell chooses a fate or behavior on the basis of information conveyed in noisy external signals. For robust decoding,

Tetsuya J. Kobayashi; Atsushi Kamimura

2011-01-01

205

Physicians' strikes and the competing bases of physicians' moral obligations.  

PubMed

Many authors have addressed the morality of physicians' strikes on the assumption that medical practice is morally different from other kinds of occupations. This article analyzes three prominent theoretical accounts that attempt to ground such special moral obligations for physicians--practice-based accounts, utilitarian accounts, and social contract accounts--and assesses their applicability to the problem of the morality of strikes. After critiquing these views, it offers a fourth view grounding special moral obligations in voluntary commitments, and explains why this is a preferable basis for understanding physicians' moral obligations in general and especially as pertaining to strikes. PMID:24199524

MacDougall, D Robert

2013-09-01

206

Capsule enlargement in Cryptococcus neoformans confers resistance to oxidative stress suggesting a mechanism for intracellular survival  

Microsoft Academic Search

Summary Cryptococcusneoformans is a facultative intracellular pathogen. The most distinctive feature of C. neofor- mans is a polysaccharide capsule that enlarges depending on environmental stimuli. The mechanism by which C. neoformans avoids killing during phago- cytosis is unknown. We hypothesized that capsule growth conferred resistance to microbicidal mol- ecules produced by the host during infection, particu- larly during phagocytosis. We

Oscar Zaragoza; Cara J. Chrisman; Maria Victoria Castelli; Susana Frases; Manuel Cuenca-Estrella; Juan Luis Rodríguez-Tudela; Arturo Casadevall

2008-01-01

207

Phylogenomic evidence supports past endosymbiosis, intracellular and horizontal gene transfer in Cryptosporidium parvum  

Microsoft Academic Search

BACKGROUND: The apicomplexan parasite Cryptosporidium parvum is an emerging pathogen capable of causing illness in humans and other animals and death in immunocompromised individuals. No effective treatment is available and the genome sequence has recently been completed. This parasite differs from other apicomplexans in its lack of a plastid organelle, the apicoplast. Gene transfer, either intracellular from an endosymbiont\\/donor organelle

Jinling Huang; Nandita Mullapudi; Cheryl A Lancto; Marla Scott; Mitchell S Abrahamsen; Jessica C Kissinger

2004-01-01

208

Draft Genome Sequence of the Fish Pathogen Piscirickettsia salmonis  

PubMed Central

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

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

2013-01-01

209

Expressed sequence tag analysis of the soybean rust pathogen Phakopsora pachyrhizi  

Microsoft Academic Search

Soybean rust is caused by the obligate fungal pathogen Phakopsora pachyrhizi Sydow. A unidirectional cDNA library was constructed using mRNA isolated from germinating P. pachyrhizi urediniospores to identify genes expressed at this physiological stage. Single pass sequence analysis of 908 clones revealed 488 unique expressed sequence tags (ESTs, unigenes) of which 107 appeared as multiple copies. BLASTX analysis identified 189

Martha Lucia Posada-Buitrago; Reid D. Frederick

2005-01-01

210

Intracellularly Induced Cyclophilins Play an Important Role in Stress Adaptation and Virulence of Brucella abortus  

PubMed Central

Brucella is an intracellular bacterial pathogen that causes the worldwide zoonotic disease brucellosis. Brucella virulence relies on its ability to transition to an intracellular lifestyle within host cells. Thus, this pathogen must sense its intracellular localization and then reprogram gene expression for survival within the host cell. A comparative proteomic investigation was performed to identify differentially expressed proteins potentially relevant for Brucella intracellular adaptation. Two proteins identified as cyclophilins (CypA and CypB) were overexpressed in the intracellular environment of the host cell in comparison to laboratory-grown Brucella. To define the potential role of cyclophilins in Brucella virulence, a double-deletion mutant was constructed and its resulting phenotype was characterized. The Brucella abortus ?cypAB mutant displayed increased sensitivity to environmental stressors, such as oxidative stress, pH, and detergents. In addition, the B. abortus ?cypAB mutant strain had a reduced growth rate at lower temperature, a phenotype associated with defective expression of cyclophilins in other microorganisms. The B. abortus ?cypAB mutant also displays reduced virulence in BALB/c mice and defective intracellular survival in HeLa cells. These findings suggest that cyclophilins are important for Brucella virulence and survival in the host cells. PMID:23230297

García Fernández, Lucía; DelVecchio, Vito G.; Briones, Gabriel

2013-01-01

211

Sulfur Production by Obligately Chemolithoautotrophic Thiobacillus Species  

PubMed Central

Transient-state experiments with the obligately autotrophic Thiobacillus sp. strain W5 revealed that sulfide oxidation proceeds in two physiological phases, (i) the sulfate-producing phase and (ii) the sulfur- and sulfate-producing phase, after which sulfide toxicity occurs. Specific sulfur-producing characteristics were independent of the growth rate. Sulfur formation was shown to occur when the maximum oxidative capacity of the culture was approached. In order to be able to oxidize increasing amounts of sulfide, the organism has to convert part of the sulfide to sulfur (HS(sup-)(symbl)S(sup0) + H(sup+) + 2e(sup-)) instead of sulfate (HS(sup-) + 4H(inf2)O(symbl)SO(inf4)(sup2-) + 9 H(sup+) + 8e(sup-)), thereby keeping the electron flux constant. Measurements of the in vivo degree of reduction of the cytochrome pool as a function of increasing sulfide supply suggested a redox-related down-regulation of the sulfur oxidation rate. Comparison of the sulfur-producing properties of Thiobacillus sp. strain W5 and Thiobacillus neapolitanus showed that the former has twice the maximum specific sulfide-oxidizing capacity of the latter (3.6 versus 1.9 (mu)mol/mg of protein/min). Their maximum specific oxygen uptake rates were very similar. Significant mechanistic differences in sulfur production between the high-sulfur-producing Thiobacillus sp. strain W5 and the moderate-sulfur-producing species T. neapolitanus were not observed. The limited sulfide-oxidizing capacity of T. neapolitanus appears to be the reason that it can convert only 50% of the incoming sulfide to elemental sulfur. PMID:16535627

Visser, J. M.; Robertson, L. A.; Van Verseveld, H. W.; Kuenen, J. G.

1997-01-01

212

7 CFR 4290.165 - Obligations of Control Persons.  

Code of Federal Regulations, 2010 CFR

...AND RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE RURAL BUSINESS INVESTMENT COMPANY (âRBICâ) PROGRAM Qualifications for the RBIC Program Organizing A Rbic § 4290.165 Obligations of Control Persons. All Control...

2010-01-01

213

7 CFR 400.168 - Obligations of participating insurance company.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF AGRICULTURE GENERAL ADMINISTRATIVE REGULATIONS Reinsurance Agreement-Standards for Approval; Regulations for the 1997 and Subsequent Reinsurance Years § 400.168 Obligations of participating insurance company. The Agreement will...

2010-01-01

214

7 CFR 400.167 - Limitations on Corporation's obligations.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF AGRICULTURE GENERAL ADMINISTRATIVE REGULATIONS Reinsurance Agreement-Standards for Approval; Regulations for the 1997 and Subsequent Reinsurance Years § 400.167 Limitations on Corporation's obligations. The Agreement will...

2010-01-01

215

7 CFR 400.166 - Obligations of the Corporation.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF AGRICULTURE GENERAL ADMINISTRATIVE REGULATIONS Reinsurance Agreement-Standards for Approval; Regulations for the 1997 and Subsequent Reinsurance Years § 400.166 Obligations of the Corporation. The Agreement will include the...

2010-01-01

216

34 CFR 686.43 - Obligation to repay the grant.  

Code of Federal Regulations, 2010 CFR

...Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION TEACHER EDUCATION ASSISTANCE FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.43...

2010-07-01

217

34 CFR 686.40 - Documenting the service obligation.  

Code of Federal Regulations, 2010 CFR

...Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION TEACHER EDUCATION ASSISTANCE FOR COLLEGE AND HIGHER EDUCATION (TEACH) GRANT PROGRAM Service and Repayment Obligations § 686.40...

2010-07-01

218

31 CFR 223.18 - Performance of agency obligations.  

Code of Federal Regulations, 2010 CFR

...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)...

2010-07-01

219

29 CFR 4.146 - Contract obligations after award, generally.  

...2014-07-01 2013-07-01 true Contract obligations after award, generally. 4.146 Section 4.146 Labor Office of the Secretary of Labor LABOR STANDARDS FOR FEDERAL SERVICE CONTRACTS Application of the...

2014-07-01

220

48 CFR 1019.202-70-14 - Obligation.  

Code of Federal Regulations, 2010 CFR

...1019.202-70-14 Section 1019.202-70-14 Federal Acquisition Regulations System DEPARTMENT OF THE TREASURY SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 1019.202-70-14 Obligation. (a) Mentor or protégé...

2010-10-01

221

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2010 CFR

...OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Metropolitan Transportation Planning and Programming § 450.332 Annual listing of obligated projects. (a) In metropolitan planning areas, on an annual...

2010-04-01

222

7 CFR 760.507 - Obligations of a participant.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

223

7 CFR 1416.705 - Obligations of a participant.  

Code of Federal Regulations, 2010 CFR

...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...

2010-01-01

224

7 CFR 783.7 - Obligations of a participant.  

Code of Federal Regulations, 2010 CFR

...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...

2010-01-01

225

7 CFR 760.507 - Obligations of a participant.  

Code of Federal Regulations, 2012 CFR

...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...

2012-01-01

226

15 CFR 782.4 - Assistance in determining your obligations.  

Code of Federal Regulations, 2010 CFR

...false Assistance in determining your obligations. 782.4 Section 782.4 Commerce and Foreign Trade Regulations Relating...INFORMATION REGARDING REPORTING REQUIREMENTS AND PROCEDURES § 782.4 Assistance in determining your...

2010-01-01

227

21 CFR 26.75 - Suspension of recognition obligations.  

Code of Federal Regulations, 2010 CFR

...MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN MEDICAL DEVICE PRODUCT EVALUATION REPORTS: UNITED STATES AND THE EUROPEAN COMMUNITY âFrameworkâ Provisions § 26.75 Suspension of recognition obligations. Either party may suspend its...

2010-04-01

228

18 CFR 367.2300 - Account 230, Asset retirement obligations.  

...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. (a) This...

2014-04-01

229

18 CFR 367.2300 - Account 230, Asset retirement obligations.  

Code of Federal Regulations, 2010 CFR

...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. (a) This...

2010-04-01

230

18 CFR 367.2300 - Account 230, Asset retirement obligations.  

Code of Federal Regulations, 2011 CFR

...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. (a) This...

2011-04-01

231

7 CFR 982.54 - Deferment of restricted obligation.  

Code of Federal Regulations, 2010 CFR

...less than the total bonding value of the handler's deferred...restricted obligation. The bonding value shall be the deferred restricted...shall be based on the estimated value of restricted credits for the current marketing year. Until bonding...

2010-01-01

232

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

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

233

7 CFR 984.54 - Establishment of obligation.  

Code of Federal Regulations, 2010 CFR

...Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Reserve Walnuts § 984.54 Establishment of obligation...kernelweight of certified merchantable walnuts equal to a quantity derived by the...

2010-01-01

234

Influence of Fragmentation on Shrubsteppe-Obligate Passerines.  

E-print Network

??I examined reproductive success and post-fledging dispersal of shrubsteppe-obligate passerines to determine if either mechanism might contribute to the reduced abundance previously reported for these… (more)

Schoeberl, Bruce C.

2003-01-01

235

24 CFR 291.565 - Continuing obligations after purchase.  

...obligations after purchase. To remain in compliance with the GNND Sales Program, the law enforcement officer, teacher, or firefighter/emergency medical technician must, for the entire duration of the owner-occupancy term: (a) Continue to...

2014-04-01

236

22 CFR 231.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2010 CFR

...false Fiscal 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...

2010-04-01

237

Identification of transposon insertion mutants of Francisella tularensis tularensis strain Schu S4 deficient in intracellular replication in the hepatic cell line HepG2  

Microsoft Academic Search

BACKGROUND: Francisella tularensis is a zoonotic intracellular bacterial pathogen that causes tularemia. The subspecies tularensis is highly virulent and is classified as a category A agent of biological warfare because of its low infectious dose by an aerosol route, and its ability to cause severe disease. In macrophages F. tularensis exhibits a rather novel intracellular lifestyle; after invasion it remains

Aiping Qin; Barbara J Mann

2006-01-01

238

TGF-beta-Mediated Sustained ERK1\\/2 Activity Promotes the Inhibition of Intracellular Growth of Mycobacterium avium in Epithelioid Cells Surrogates  

Microsoft Academic Search

Transforming growth factor beta (TGF-?) has been implicated in the pathogenesis of several diseases including infection with intracellular pathogens such as the Mycobacterium avium complex. Infection of macrophages with M. avium induces TGF-? production and neutralization of this cytokine has been associated with decreased intracellular bacterial growth. We have previously demonstrated that epithelioid cell surrogates (ECs) derived from primary murine

Carolina L'Abbate; Ivone Cipriano; Elizabeth Cristina Pérez-Hurtado; Sylvia Cardoso Leão; Célia Regina Whitaker Carneiro; Joel Machado; Guillaume Dalmasso

2011-01-01

239

Obligate insect endosymbionts exhibit increased ortholog length variation and loss of large accessory proteins concurrent with genome shrinkage.  

PubMed

Extreme genome reduction has been observed in obligate intracellular insect mutualists and is an assumed consequence of fixed, long-term host isolation. Rapid accumulation of mutations and pseudogenization of genes no longer vital for an intracellular lifestyle, followed by deletion of many genes, are factors that lead to genome reduction. Size reductions in individual genes due to small-scale deletions have also been implicated in contributing to overall genome shrinkage. Conserved protein functional domains are expected to exhibit low tolerance for mutations and therefore remain relatively unchanged throughout protein length reduction while nondomain regions, presumably under less selective pressures, would shorten. This hypothesis was tested using orthologous protein sets from the Flavobacteriaceae (phylum: Bacteroidetes) and Enterobacteriaceae (subphylum: Gammaproteobacteria) families, each of which includes some of the smallest known genomes. Upon examination of protein, functional domain, and nondomain region lengths, we found that proteins were not uniformly shrinking with genome reduction, but instead increased length variability and variability was observed in both the functional domain and nondomain regions. Additionally, as complete gene loss also contributes to overall genome shrinkage, we found that the largest proteins in the proteomes of nonhost-restricted bacteroidetial and gammaproteobacterial species often were inferred to be involved in secondary metabolic processes, extracellular sensing, or of unknown function. These proteins were absent in the proteomes of obligate insect endosymbionts. Therefore, loss of genes encoding large proteins not required for host-restricted lifestyles in obligate endosymbiont proteomes likely contributes to extreme genome reduction to a greater degree than gene shrinkage. PMID:24671745

Kenyon, Laura J; Sabree, Zakee L

2014-04-01

240

Obligate Insect Endosymbionts Exhibit Increased Ortholog Length Variation and Loss of Large Accessory Proteins Concurrent with Genome Shrinkage  

PubMed Central

Extreme genome reduction has been observed in obligate intracellular insect mutualists and is an assumed consequence of fixed, long-term host isolation. Rapid accumulation of mutations and pseudogenization of genes no longer vital for an intracellular lifestyle, followed by deletion of many genes, are factors that lead to genome reduction. Size reductions in individual genes due to small-scale deletions have also been implicated in contributing to overall genome shrinkage. Conserved protein functional domains are expected to exhibit low tolerance for mutations and therefore remain relatively unchanged throughout protein length reduction while nondomain regions, presumably under less selective pressures, would shorten. This hypothesis was tested using orthologous protein sets from the Flavobacteriaceae (phylum: Bacteroidetes) and Enterobacteriaceae (subphylum: Gammaproteobacteria) families, each of which includes some of the smallest known genomes. Upon examination of protein, functional domain, and nondomain region lengths, we found that proteins were not uniformly shrinking with genome reduction, but instead increased length variability and variability was observed in both the functional domain and nondomain regions. Additionally, as complete gene loss also contributes to overall genome shrinkage, we found that the largest proteins in the proteomes of nonhost-restricted bacteroidetial and gammaproteobacterial species often were inferred to be involved in secondary metabolic processes, extracellular sensing, or of unknown function. These proteins were absent in the proteomes of obligate insect endosymbionts. Therefore, loss of genes encoding large proteins not required for host-restricted lifestyles in obligate endosymbiont proteomes likely contributes to extreme genome reduction to a greater degree than gene shrinkage. PMID:24671745

Kenyon, Laura J.; Sabree, Zakee L.

2014-01-01

241

Mycoplasma hominis and Trichomonas vaginalis: a unique case of symbiotic relationship between two obligate human parasites.  

PubMed

Mollicutes are the smallest and simplest self-replicating microorganisms. Despite the minimal genome and apparent lack of complexity, mycoplasmas show a high degree of adaptation to the most diverse environments. Mycoplasma hominis is a human sexually transmitted mycoplasma which is able to establish a biological association with Trichomonas vaginalis, a pathogenic flagellated protist. M. hominis and T. vaginalis share the same specific natural niche, the human genitourinary tract. Symbiotic relationships between unicellular eukaryotes and bacteria are well known and have been extensively studied, providing interesting insights into the biology of one or both the symbionts. The relationship between T. vaginalis and M. hominis is unique in that it was the first described association of two obligated human parasites. Several aspects of this relationship have been investigated, showing how the trichomonad may be viewed not only as a new niche for M. hominis, but also as a "Trojan horse" for the transmission of the bacterial infection to the human host. PMID:16720288

Dessì, Daniele; Rappelli, Paola; Diaz, Nicia; Cappuccinelli, Piero; Fiori, Pier Luigi

2006-01-01

242

Comparative analysis of Chlamydia psittaci genomes reveals the recent emergence of a pathogenic lineage with a broad host range.  

PubMed

Chlamydia psittaci is an obligate intracellular bacterium. Interest in Chlamydia stems from its high degree of virulence as an intestinal and pulmonary pathogen across a broad range of animals, including humans. C. psittaci human pulmonary infections, referred to as psittacosis, can be life-threatening, which is why the organism was developed as a bioweapon in the 20th century and is listed as a CDC biothreat agent. One remarkable recent result from comparative genomics is the finding of frequent homologous recombination across the genome of the sexually transmitted and trachoma pathogen Chlamydia trachomatis. We sought to determine if similar evolutionary dynamics occurred in C. psittaci. We analyzed 20 C. psittaci genomes from diverse strains representing the nine known serotypes of the organism as well as infections in a range of birds and mammals, including humans. Genome annotation revealed a core genome in all strains of 911 genes. Our analyses showed that C. psittaci has a history of frequently switching hosts and undergoing recombination more often than C. trachomatis. Evolutionary history reconstructions showed genome-wide homologous recombination and evidence of whole-plasmid exchange. Tracking the origins of recombinant segments revealed that some strains have imported DNA from as-yet-unsampled or -unsequenced C. psittaci lineages or other Chlamydiaceae species. Three ancestral populations of C. psittaci were predicted, explaining the current population structure. Molecular clock analysis found that certain strains are part of a clonal epidemic expansion likely introduced into North America by South American bird traders, suggesting that psittacosis is a recently emerged disease originating in New World parrots. PMID:23532978

Read, Timothy D; Joseph, Sandeep J; Didelot, Xavier; Liang, Brooke; Patel, Lisa; Dean, Deborah

2013-01-01

243

Pathogen Life-History Trade-Offs Revealed in Allopatry  

PubMed Central

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

Susi, Hanna; Laine, Anna-Liisa

2013-01-01

244

Tick vaccines and the control of tick-borne pathogens  

PubMed Central

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

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

2013-01-01

245

Original article Mannitol enhances intracellular calcium diffusion  

E-print Network

Cedex 03, France b Department of Biostructure and Function, University of Connecticut Health Center intracellular calcium will raise the effective intracellular gradient and thereby amplify intracellular calcium]. It has been known for many years that sugars like lactose, or polyols like sorbitol or mannitol, when

Paris-Sud XI, Université de

246

Intracellular ion channels and cancer  

PubMed Central

Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome, and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K+ channels (Ca2+-dependent BKCa and IKCa, ATP-dependent KATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K+ channel-3 (TASK-3)), Ca2+ uniporter MCU, Mg2+-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC) and the Permeability Transition Pore (MPTP) contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER)-located inositol 1,4,5-trisphosphate (IP3) receptor, the ER-located Ca2+ depletion sensor STIM1 (stromal interaction molecule 1), a component of the store-operated Ca2+ channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment. PMID:24027528

Leanza, Luigi; Biasutto, Lucia; Manago, Antonella; Gulbins, Erich; Zoratti, Mario; Szabo, Ildiko

2013-01-01

247

Barcoding Hedgehog for Intracellular Transport  

NSDL National Science Digital Library

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.

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

2011-11-22

248

What are the public obligations to AIDS patients?  

PubMed

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

Kelley, David

2002-01-01

249

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

PubMed Central

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

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

2013-01-01

250

The ClpP protease homologue is required for the transmission traits and cell division of the pathogen Legionella pneumophila  

Microsoft Academic Search

BACKGROUND: Legionella pneumophila, the intracellular bacterial pathogen that causes Legionnaires' disease, exhibit characteristic transmission traits such as elevated stress tolerance, shortened length and virulence during the transition from the replication phase to the transmission phase. ClpP, the catalytic core of the Clp proteolytic complex, is widely involved in many cellular processes via the regulation of intracellular protein quality. RESULTS: In

Xiang-hui Li; Yong-lun Zeng; Ye Gao; Xiao-cong Zheng; Qin-fen Zhang; Shi-ning Zhou; Yong-jun Lu

2010-01-01

251

Environmental and safety obligations of the Chemical Weapons Convention  

SciTech Connect

Among its many unique and precedent-setting provisions, the Chemical Weapons Convention (CWC) includes important requirements for States Parties to protect the public safety and the environment in the course of carrying out the treaty. These obligations will apply to the destruction of chemical weapons, of former chemical weapons production facilities, and to other activities under the Convention such as the verification scheme. This morning, I will briefly discuss the Convention`s safety and environmental obligations, concentrating on their effects in this country as the United States chemical weapons stockpile is destroyed.

Tanzman, E.A.

1994-04-07

252

The effects of macrophage source on the mechanism of phagocytosis and intracellular survival of Leishmania  

PubMed Central

Leishmania spp. protozoa are obligate intracellular parasites that replicate in macrophages during mammalian infection. Efficient phagocytosis and survival in macrophages are important determinants of parasite virulence. Macrophage lines differ dramatically in their ability to sustain intracellular Leishmania infantum chagasi (Lic). We report that the U937 monocytic cell line supported the intracellular replication and cell-to-cell spread of Lic during 72 hours after parasite addition, whereas primary human monocyte-derived macrophages (MDMs) did not. Electron microscopy and live cell imaging illustrated that Lic promastigotes anchored to MDMs via their anterior ends and were engulfed through symmetrical pseudopods. In contrast, U937 cells bound Lic in diverse orientations, and extended membrane lamellae to reorient and internalize parasites through coiling phagocytosis. Lic associated tightly with the parasitophorous vacuole (PV) membrane in both cell types. PVs fused with LAMP-1-expressing compartments 24 hours after phagocytosis by MDMs, whereas U937 cell PVs remained LAMP-1 negative. The expression of one phagocytic receptor (CR3) was higher in MDMs than U937 cells, leading us to speculate that parasite uptake proceeds through dissimilar pathways between these cells. We hypothesize that the mechanism of phagocytosis differs between primary versus immortalized human macrophage cells, with corresponding differences in the subsequent intracellular fate of the parasite. PMID:21723411

Hsiao, Chia-Hung Christine; Ueno, Norikiyo; Shao, Jian Q.; Schroeder, Kristin R.; Moore, Kenneth C.; Donelson, John E.; Wilson, Mary E.

2011-01-01

253

Stress adaptation in a pathogenic fungus  

PubMed Central

Candida albicans is a major fungal pathogen of humans. This yeast is carried by many individuals as a harmless commensal, but when immune defences are perturbed it causes mucosal infections (thrush). Additionally, when the immune system becomes severely compromised, C. albicans often causes life-threatening systemic infections. A battery of virulence factors and fitness attributes promote the pathogenicity of C. albicans. Fitness attributes include robust responses to local environmental stresses, the inactivation of which attenuates virulence. Stress signalling pathways in C. albicans include evolutionarily conserved modules. However, there has been rewiring of some stress regulatory circuitry such that the roles of a number of regulators in C. albicans have diverged relative to the benign model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. This reflects the specific evolution of C. albicans as an opportunistic pathogen obligately associated with warm-blooded animals, compared with other yeasts that are found across diverse environmental niches. Our understanding of C. albicans stress signalling is based primarily on the in vitro responses of glucose-grown cells to individual stresses. However, in vivo this pathogen occupies complex and dynamic host niches characterised by alternative carbon sources and simultaneous exposure to combinations of stresses (rather than individual stresses). It has become apparent that changes in carbon source strongly influence stress resistance, and that some combinatorial stresses exert non-additive effects upon C. albicans. These effects, which are relevant to fungus–host interactions during disease progression, are mediated by multiple mechanisms that include signalling and chemical crosstalk, stress pathway interference and a biological transistor. PMID:24353214

Brown, Alistair J. P.; Budge, Susan; Kaloriti, Despoina; Tillmann, Anna; Jacobsen, Mette D.; Yin, Zhikang; Ene, Iuliana V.; Bohovych, Iryna; Sandai, Doblin; Kastora, Stavroula; Potrykus, Joanna; Ballou, Elizabeth R.; Childers, Delma S.; Shahana, Shahida; Leach, Michelle D.

2014-01-01

254

How complex are intracellular immune receptor signaling complexes?  

PubMed Central

Nucleotide binding leucine-rich repeat proteins (NLRs) are the major class of intracellular immune receptors in plants. NLRs typically function to specifically recognize pathogen effectors and to initiate and control defense responses that severely limit pathogen growth in plants (termed effector-triggered immunity, or ETI). Despite numerous reports supporting a central role in innate immunity, the molecular mechanisms driving NLR activation and downstream signaling remain largely elusive. Recent reports shed light on the pre- and post-activation dynamics of a few NLR-containing protein complexes. Recent technological advances in the use of proteomics may enable high-resolution definition of immune protein complexes and possible activation-relevant post-translational modifications of the components in these complexes. In this review, we focus on research aimed at characterizing pre- and post-activation NLR protein complexes and the molecular events that follow activation. We discuss the use of new or improved technologies as tools to unveil the molecular mechanisms that define NLR-mediated pathogen recognition. PMID:23109935

Bonardi, Vera; Dangl, Jeffery L.

2012-01-01

255

The intracellular galactoglycome in Trichoderma reesei during growth on lactose.  

PubMed

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

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

256

Pathogenic adaptations to host-derived antibacterial copper  

PubMed Central

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

Chaturvedi, Kaveri S.; Henderson, Jeffrey P.

2014-01-01

257

Vaccines against dangerous pathogens  

Microsoft Academic Search

Dangerous pathogens are defined by the UK Health and Safety Executive's advisory committee as category 3 (those which cause severe human disease for which prophylaxis or therapy is usually available) or category 4 (as for category 3, but for which prophylaxis or therapy is not available). Research and development of vaccines for such pathogens is challenging, due to the safety

E D Williamson; R W Titball

2002-01-01

258

Emerging Escherichia pathogen.  

PubMed

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

Kaewpoowat, Quanhathai; Permpalung, Nitipong; Sentochnik, Deborah E

2013-08-01

259

Emerging Escherichia Pathogen  

PubMed Central

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

Permpalung, Nitipong; Sentochnik, Deborah E.

2013-01-01

260

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...

261

Plant pathogen resistance  

DOEpatents

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.

Greenberg, Jean T; Jung, Ho Won; Tschaplinski, Timothy

2012-11-27

262

Delineation of Diverse Macrophage Activation Programs in Response to Intracellular Parasites and Cytokines  

PubMed Central

Background The ability to reside and proliferate in macrophages is characteristic of several infectious agents that are of major importance to public health, including the intracellular parasites Trypanosoma cruzi (the etiological agent of Chagas disease) and Leishmania species (etiological agents of Kala-Azar and cutaneous leishmaniasis). Although recent studies have elucidated some of the ways macrophages respond to these pathogens, the relationships between activation programs elicited by these pathogens and the macrophage activation programs elicited by bacterial pathogens and cytokines have not been delineated. Methodology/Principal Findings To provide a global perspective on the relationships between macrophage activation programs and to understand how certain pathogens circumvent them, we used transcriptional profiling by genome-wide microarray analysis to compare the responses of mouse macrophages following exposure to the intracellular parasites T. cruzi and Leishmania mexicana, the bacterial product lipopolysaccharide (LPS), and the cytokines IFNG, TNF, IFNB, IL-4, IL-10, and IL-17. We found that LPS induced a classical activation state that resembled macrophage stimulation by the Th1 cytokines IFNG and TNF. However, infection by the protozoan pathogen L. mexicana produced so few transcriptional changes that the infected macrophages were almost indistinguishable from uninfected cells. T. cruzi activated macrophages produced a transcriptional signature characterized by the induction of interferon-stimulated genes by 24 h post-infection. Despite this delayed IFN response by T. cruzi, the transcriptional response of macrophages infected by the kinetoplastid pathogens more closely resembled the transcriptional response of macrophages stimulated by the cytokines IL-4, IL-10, and IL-17 than macrophages stimulated by Th1 cytokines. Conclusions/Significance This study provides global gene expression data for a diverse set of biologically significant pathogens and cytokines and identifies the relationships between macrophage activation states induced by these stimuli. By comparing macrophage activation programs to pathogens and cytokines under identical experimental conditions, we provide new insights into how macrophage responses to kinetoplastids correlate with the overall range of macrophage activation states. PMID:20361029

Zhang, Shuyi; Kim, Charles C.; Batra, Sajeev; McKerrow, James H.; Loke, P'ng

2010-01-01

263

CHANGING OBLIGATIONS AND THE PSYCHOLOGICAL CONTRACT: A LONGITUDINAL STUDY  

Microsoft Academic Search

In an exploratory longitudinal study of business school alumni, we investigated changes in employment obligations as perceived by em- ployees. During the first two years of employment, employees came to perceive that they owed less to their employers while seeing tbeir em- ployers as owing them more. An employer's failure to fulfill its com- mitments was found to be significantly

SANDRA L. ROBINSON; MATTHEW S. KRAATZ; DENISE M. ROUSSEAU

1994-01-01

264

47 CFR 76.56 - Signal carriage obligations.  

Code of Federal Regulations, 2010 CFR

...than 50 percent of the broadcast week. For purposes of this definition, only identical episodes of a television series are considered...must-carry obligations may do so, subject to approval by the franchising authority pursuant to Section 611 of the...

2010-10-01

265

European air transport public service obligations: a periodic review  

Microsoft Academic Search

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

Aisling Reynolds-Feighan

1995-01-01

266

Filial obligations to elderly parents: a duty to care?  

PubMed Central

A continuing need for care for elderly, combined with looser family structures prompt the question what filial obligations are. Do adult children of elderly have a duty to care? Several theories of filial obligation are reviewed. The reciprocity argument is not sensitive to the parent–child relationship after childhood. A theory of friendship does not offer a correct parallel for the relationship between adult child and elderly parent. Arguments based on need or vulnerability run the risk of being unjust to those on whom a needs-based claim is laid. To compare filial obligations with promises makes too much of parents’ expectations, however reasonable they may be. The good of being in an unchosen relationship seems the best basis for filial obligations, with an according duty to maintain the relationship when possible. We suggest this relationship should be maintained even if one of the parties is no longer capable of consciously contributing to it. We argue that this entails a duty to care about one’s parents, not for one’s parents. This implies that care for the elderly is not in the first place a task for adult children. PMID:20922568

Van Delden, Johannes J. M.

2010-01-01

267

Wild dogs, Lycaon pictus, are a social species, obligated  

E-print Network

conditions apply for the African wild dog, Lycaon pictus, and data on this species in Zimbabwe support ourWild dogs, Lycaon pictus, are a social species, obligated to breed in a group, in which only one extinctions?: The case of wild dogs Angulo et al. Angulo et al. Frontiers in Zoology 2013, 10:11 http

Courchamp, Franck

268

11 CFR 9034.5 - Net outstanding campaign obligations.  

Code of Federal Regulations, 2010 CFR

...was determined. (e) Contributions received from joint fundraising activities conducted under 11 CFR 9034.8 may be used to...obligations as of the date these funds are received by the fundraising representative committee and shall be included in the...

2010-01-01

269

11 CFR 9034.5 - Net outstanding campaign obligations.  

Code of Federal Regulations, 2011 CFR

...was determined. (e) Contributions received from joint fundraising activities conducted under 11 CFR 9034.8 may be used to...obligations as of the date these funds are received by the fundraising representative committee and shall be included in the...

2011-01-01

270

Specifying and monitoring economic environments using rights and obligations  

Microsoft Academic Search

We provide a formal scripting language to capture the semantics of economic environments. The language is based on a set of well-defined design principles and makes explicit an agent's rights, as derived from property, and an agent's obligations, as derived from restrictions placed on its actions either voluntarily or as a consequence of other actions. Coupled with the language is

Loizos Michael; David C. Parkes; Avi Pfeffer

2010-01-01

271

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2012 CFR

...Metropolitan Transportation Planning and Programming § 450.332 Annual listing of...for which funds under 23 U.S.C. or 49 U.S.C. Chapter 53 were obligated in the...available for subsequent years. (c) The listing shall be...

2012-04-01

272

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2013 CFR

...Metropolitan Transportation Planning and Programming § 450.332 Annual listing of...for which funds under 23 U.S.C. or 49 U.S.C. Chapter 53 were obligated in the...available for subsequent years. (c) The listing shall be...

2013-04-01

273

23 CFR 450.332 - Annual listing of obligated projects.  

...Metropolitan Transportation Planning and Programming § 450.332 Annual listing of...for which funds under 23 U.S.C. or 49 U.S.C. Chapter 53 were obligated in the...available for subsequent years. (c) The listing shall be...

2014-04-01

274

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2011 CFR

...Metropolitan Transportation Planning and Programming § 450.332 Annual listing of...for which funds under 23 U.S.C. or 49 U.S.C. Chapter 53 were obligated in the...available for subsequent years. (c) The listing shall be...

2011-04-01

275

Acts of Commanding and Changing Obligations Tomoyuki Yamada  

E-print Network

Acts of Commanding and Changing Obligations Tomoyuki Yamada Graduate School of Letters, Hokkaido. In what follows, I will try to model changes brought about by various acts of commanding in terms of a variant of update logic. I will combine a multi-agent variant of the language of monadic deontic logic

Amsterdam, University of

276

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

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

Manzano-Marín, Alejandro; Latorre, Amparo

2014-07-01

277

What are bloodborne pathogens? Bloodborne pathogens are infectious materials  

E-print Network

available Hepatitis B vaccinations to all employees with occupational exposure to bloodborne pathogens receive regular training that covers the dangers of bloodborne pathogens, preventive practices, and post

Pawlowski, Wojtek

278

Recent developments in copper and zinc homeostasis in bacterial pathogens.  

PubMed

Copper and zinc homeostasis systems in pathogenic bacteria are required to resist host efforts to manipulate the availability and toxicity of these metal ions. Central to this microbial adaptive response is the involvement of metal-trafficking and metal-sensing proteins that ultimately exercise control of metal speciation in the cell. Cu-specific and Zn-specific metalloregulatory proteins regulate the transcription of metal-responsive genes while metallochaperones and related proteins ensure that these metals are appropriately buffered by the intracellular milieu and delivered to correct intracellular targets. In this review, we summarize recent findings on how bacterial pathogens mount a metal-specific response to derail host efforts to win the 'fight over metals.' PMID:24463765

Braymer, Joseph J; Giedroc, David P

2014-04-01

279

30 CFR 585.900 - Who must meet the decommissioning obligations in this subpart?  

Code of Federal Regulations, 2012 CFR

... Environmental and Safety Management, Inspections, and Facility Assessments for Activities Conducted Under SAPs, COPs and GAPs Decommissioning Obligations and Requirements § 585.900 Who must meet the decommissioning obligations in this...

2012-07-01

280

30 CFR 585.901 - When do I accrue decommissioning obligations?  

Code of Federal Regulations, 2012 CFR

... Environmental and Safety Management, Inspections, and Facility Assessments for Activities Conducted Under SAPs, COPs and GAPs Decommissioning Obligations and Requirements § 585.901 When do I accrue decommissioning obligations? You accrue...

2012-07-01

281

18 CFR 37.5 - Obligations of Transmission Providers and Responsible Parties.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Obligations of Transmission Providers and Responsible Parties...SYSTEMS § 37.5 Obligations of Transmission Providers and Responsible Parties. (a) Each Transmission Provider is required to provide...

2012-04-01

282

Federal Agencies' AcademicS&E Obligations Continued to Climb in FY 1995  

NSF Publications Database

Federal Agencies' Academic S&E Obligations Continued to Climb in FY 1995 (May 16, 1997) This Data ... analytic summary of Federal academic science and engineering obligations collected through the ...

283

40 CFR 152.97 - Rights and obligations of data submitters.  

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

284

40 CFR 152.97 - Rights and obligations of data submitters.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

285

40 CFR 152.97 - Rights and obligations of data submitters.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

286

28 CFR 811.5 - Commencement of the obligation to register.  

Code of Federal Regulations, 2013 CFR

...AGENCY FOR THE DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.5 Commencement...obligation to register. (a) A sex offender's obligation to register starts when the sex offender is found guilty or not...

2013-07-01

287

28 CFR 811.5 - Commencement of the obligation to register.  

Code of Federal Regulations, 2011 CFR

...AGENCY FOR THE DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.5 Commencement...obligation to register. (a) A sex offender's obligation to register starts when the sex offender is found guilty or not...

2011-07-01

288

28 CFR 811.5 - Commencement of the obligation to register.  

Code of Federal Regulations, 2012 CFR

...AGENCY FOR THE DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.5 Commencement...obligation to register. (a) A sex offender's obligation to register starts when the sex offender is found guilty or not...

2012-07-01

289

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

290

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

291

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

292

18 CFR 37.5 - Obligations of Transmission Providers and Responsible Parties.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Obligations of Transmission Providers and Responsible Parties...SYSTEMS § 37.5 Obligations of Transmission Providers and Responsible Parties. (a) Each Transmission Provider is required to provide...

2011-04-01

293

18 CFR 37.5 - Obligations of Transmission Providers and Responsible Parties.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Obligations of Transmission Providers and Responsible Parties...SYSTEMS § 37.5 Obligations of Transmission Providers and Responsible Parties. (a) Each Transmission Provider is required to provide...

2010-04-01

294

59 FR- Statement of the Commission Regarding Disclosure Obligations of Municipal Securities Issuers and...  

Federal Register 2010, 2011, 2012, 2013

...Statement of the Commission Regarding Disclosure Obligations; Final Rule 17 CFR Part 240 Municipal Securities Disclosure and Confirmation of Transactions...Statement of the Commission Regarding Disclosure Obligations of Municipal...

1994-03-17

295

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

Code of Federal Regulations, 2012 CFR

...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...

2012-04-01

296

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

...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...

2014-04-01

297

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

Code of Federal Regulations, 2010 CFR

...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...

2010-04-01

298

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

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

299

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

Code of Federal Regulations, 2011 CFR

...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...

2011-04-01

300

29 CFR 37.27 - What are the obligations of small recipients regarding Equal Opportunity Officers?  

Code of Federal Regulations, 2010 CFR

...obligations of small recipients regarding Equal Opportunity Officers? 37.27 Section 37...IMPLEMENTATION OF THE NONDISCRIMINATION AND EQUAL OPPORTUNITY PROVISIONS OF THE WORKFORCE INVESTMENT...obligations of small recipients regarding Equal Opportunity Officers? Although small...

2010-07-01

301

29 CFR 37.26 - What are a recipient's obligations relating to the Equal Opportunity Officer?  

Code of Federal Regulations, 2010 CFR

...recipient's obligations relating to the Equal Opportunity Officer? 37.26 Section 37.26...IMPLEMENTATION OF THE NONDISCRIMINATION AND EQUAL OPPORTUNITY PROVISIONS OF THE WORKFORCE INVESTMENT...recipient's obligations relating to the Equal Opportunity Officer? A recipient has the...

2010-07-01

302

29 CFR 37.29 - What are a recipient's obligations to disseminate its equal opportunity policy?  

Code of Federal Regulations, 2010 CFR

...obligations to disseminate its equal opportunity policy? 37.29 Section 37.29...IMPLEMENTATION OF THE NONDISCRIMINATION AND EQUAL OPPORTUNITY PROVISIONS OF THE WORKFORCE INVESTMENT...obligations to disseminate its equal opportunity policy? (a) A recipient...

2010-07-01

303

12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

304

12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.  

Code of Federal Regulations, 2013 CFR

...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...

2013-01-01

305

12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.  

...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...

2014-01-01

306

12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.  

Code of Federal Regulations, 2010 CFR

...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...

2010-01-01

307

12 CFR 1511.5 - Obligations of Funding Corporation; no adverse claims.  

Code of Federal Regulations, 2012 CFR

...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...

2012-01-01

308

26 CFR 1.662(a)-4 - Amounts used in discharge of a legal obligation.  

Code of Federal Regulations, 2011 CFR

...exists whether or not the parent's earnings and resources...law. In the case of a parent's obligation to support his child, to the extent that the parent's legal obligation...it is to be determined without consideration of the...

2011-04-01

309

26 CFR 1.662(a)-4 - Amounts used in discharge of a legal obligation.  

Code of Federal Regulations, 2013 CFR

...exists whether or not the parent's earnings and resources...law. In the case of a parent's obligation to support his child, to the extent that the parent's legal obligation...it is to be determined without consideration of the...

2013-04-01

310

26 CFR 1.662(a)-4 - Amounts used in discharge of a legal obligation.  

Code of Federal Regulations, 2012 CFR

...exists whether or not the parent's earnings and resources...law. In the case of a parent's obligation to support his child, to the extent that the parent's legal obligation...it is to be determined without consideration of the...

2012-04-01

311

26 CFR 1.662(a)-4 - Amounts used in discharge of a legal obligation.  

Code of Federal Regulations, 2010 CFR

...exists whether or not the parent's earnings and resources...law. In the case of a parent's obligation to support his child, to the extent that the parent's legal obligation...it is to be determined without consideration of the...

2010-04-01

312

31 CFR 354.5 - Obligations of Sallie Mae; no adverse claims.  

Code of Federal Regulations, 2010 CFR

...false Obligations of Sallie Mae; no adverse claims. 354.5 Section 354.5 Money and Finance: Treasury Regulations Relating...STUDENT LOAN MARKETING ASSOCIATION (SALLIE MAE) § 354.5 Obligations of Sallie Mae; no adverse...

2010-07-01

313

78 FR 63276 - Interim Policy, FAA Review of Solar Energy System Projects on Federally Obligated Airports  

Federal Register 2010, 2011, 2012, 2013

...Interim Policy, FAA Review of Solar Energy System Projects on Federally Obligated...obligated airports to construct solar energy systems on airport property. FAA...measuring ocular impact of proposed solar energy systems which are effective...

2013-10-23

314

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

315

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

316

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

317

31 CFR 103.52 - Photographic or other reproductions of Government obligations.  

Code of Federal Regulations, 2010 CFR

...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...

2010-07-01

318

43 CFR 3137.41 - What continuing development obligations must I define in a unit agreement?  

Code of Federal Regulations, 2012 CFR

...continuing development obligations must I define in a unit agreement? A unit agreement must provide for submission of supplemental...initial obligations — (a) Meets or exceeds the rate of non-unit operations in the vicinity of the unit; and...

2012-10-01

319

43 CFR 3137.41 - What continuing development obligations must I define in a unit agreement?  

Code of Federal Regulations, 2013 CFR

...continuing development obligations must I define in a unit agreement? A unit agreement must provide for submission of supplemental...initial obligations — (a) Meets or exceeds the rate of non-unit operations in the vicinity of the unit; and...

2013-10-01

320

43 CFR 3137.41 - What continuing development obligations must I define in a unit agreement?  

Code of Federal Regulations, 2011 CFR

...continuing development obligations must I define in a unit agreement? A unit agreement must provide for submission of supplemental...initial obligations — (a) Meets or exceeds the rate of non-unit operations in the vicinity of the unit; and...

2011-10-01

321

46 CFR 287.22 - Time extensions for expenditure or obligation.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Time extensions for expenditure or obligation. 287...CONSTRUCTION RESERVE FUNDS § 287.22 Time extensions for expenditure or obligation. (a) Extensions. The Administration, upon...

2010-10-01

322

26 CFR 2.1-22 - Time extensions for expenditure or obligation.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Time extensions for expenditure or obligation. 2...CONSTRUCTION RESERVE FUND § 2.1-22 Time extensions for expenditure or obligation. (a) Extensions. The Administration, upon...

2010-04-01

323

18 CFR 292.309 - Termination of obligation to purchase from qualifying facilities.  

Code of Federal Regulations, 2013 CFR

...contract that expires by its own terms is a “new contract or obligation” without a continuing obligation...PJM Interconnection, L.L.C. (PJM), ISO New England, Inc. (ISO-NE), and New York Independent System Operator (NYISO)...

2013-04-01

324

18 CFR 292.309 - Termination of obligation to purchase from qualifying facilities.  

Code of Federal Regulations, 2011 CFR

...contract that expires by its own terms is a “new contract or obligation” without a continuing obligation...PJM Interconnection, L.L.C. (PJM), ISO New England, Inc. (ISO-NE), and New York Independent System Operator (NYISO)...

2011-04-01

325

18 CFR 292.309 - Termination of obligation to purchase from qualifying facilities.  

Code of Federal Regulations, 2012 CFR

...contract that expires by its own terms is a “new contract or obligation” without a continuing obligation...PJM Interconnection, L.L.C. (PJM), ISO New England, Inc. (ISO-NE), and New York Independent System Operator (NYISO)...

2012-04-01

326

18 CFR 292.309 - Termination of obligation to purchase from qualifying facilities.  

Code of Federal Regulations, 2010 CFR

...contract that expires by its own terms is a “new contract or obligation” without a continuing obligation...PJM Interconnection, L.L.C. (PJM), ISO New England, Inc. (ISO-NE), and New York Independent System Operator (NYISO)...

2010-04-01

327

28 CFR 43.2 - Obligations of persons receiving care and treatment.  

...false Obligations of persons receiving care and treatment. 43.2 Section 43...RECOVERY OF COST OF HOSPITAL AND MEDICAL CARE AND TREATMENT FURNISHED BY THE UNITED STATES...2 Obligations of persons receiving care and treatment. (a) In the...

2014-07-01

328

28 CFR 45.10 - Procedures to promote compliance with crime victims' rights obligations.  

Code of Federal Regulations, 2011 CFR

... 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....

2011-07-01

329

40 CFR 152.97 - Rights and obligations of data submitters.  

Code of Federal Regulations, 2010 CFR

... 23 2010-07-01 2010-07-01 false Rights and obligations of data submitters. 152.97...Procedures To Ensure Protection of Data Submitters' Rights § 152.97 Rights and obligations of data submitters. (a)...

2010-07-01

330

18 CFR 292.303 - Electric utility obligations under this subpart.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 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...

2012-04-01

331

18 CFR 292.303 - Electric utility obligations under this subpart.  

Code of Federal Regulations, 2011 CFR

...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...

2011-04-01

332

Legionella pneumophila Philadelphia1 tatB and tatC affect intracellular replication and biofilm formation  

Microsoft Academic Search

Legionella pneumophila is a facultative intracellular human pathogen and an important cause of Legionnaires’ disease, a severe form of pneumonia. Recently, we showed the presence of a putative twin-arginine translocation (Tat) pathway in L. pneumophila Philadelphia-1. This secretion pathway is used to transport completely folded proteins across the cytoplasmic membrane. The importance of the Tat pathway in L. pneumophila was

Emmy De Buck; Liesbeth Maes; Eef Meyen; Lieve Van Mellaert; Nick Geukens; Jozef Anné; Elke Lammertyn

2005-01-01

333

Smooth and rough lipopolysaccharide phenotypes of Brucella induce different intracellular trafficking and cytokine\\/chemokine release in human monocytes  

Microsoft Academic Search

Virulence of the intracellular pathogen Brucella for humans is mainly associated with its lipopolysaccharide (LPS) phenotype, with smooth LPS phenotypes generally being virulent and rough ones not. The reason for this association is not quite understood. We now demonstrate by flow cytometry, electron microscopy, and ELISA that human peripheral blood monocytes interact both quantitatively and qualitatively different with smooth and

Michael G. Rittig; Andreas Kaufmann; Adrian Robins; Barry Shaw; Hans Sprenger; Diethard Gemsa; Vincent Foulongne; Bruno Rouot; Jacques Dornand

2003-01-01

334

42 CFR 68a.14 - When can a CR-LRP payment obligation be discharged in bankruptcy?  

Code of Federal Regulations, 2010 CFR

...payment obligation be discharged in bankruptcy? 68a.14 Section 68a.14...payment obligation be discharged in bankruptcy? Any payment obligation incurred...68a.12 may be discharged in bankruptcy under Title 11 of the...

2010-10-01

335

Dynamics of intracellular information decoding.  

PubMed

A variety of cellular functions are robust even to substantial intrinsic and extrinsic noise in intracellular reactions and the environment that could be strong enough to impair or limit them. In particular, of substantial importance is cellular decision-making in which a cell chooses a fate or behavior on the basis of information conveyed in noisy external signals. For robust decoding, the crucial step is filtering out the noise inevitably added during information transmission. As a minimal and optimal implementation of such an information decoding process, the autocatalytic phosphorylation and autocatalytic dephosphorylation (aPadP) cycle was recently proposed. Here, we analyze the dynamical properties of the aPadP cycle in detail. We describe the dynamical roles of the stationary and short-term responses in determining the efficiency of information decoding and clarify the optimality of the threshold value of the stationary response and its information-theoretical meaning. Furthermore, we investigate the robustness of the aPadP cycle against the receptor inactivation time and intrinsic noise. Finally, we discuss the relationship among information decoding with information-dependent actions, bet-hedging and network modularity. PMID:21832798

Kobayashi, Tetsuya J; Kamimura, Atsushi

2011-10-01

336

Glacial refugia in pathogens: European genetic structure of anther smut pathogens on Silene latifolia and Silene dioica.  

PubMed

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

Vercken, Elodie; Fontaine, Michael C; Gladieux, Pierre; Hood, Michael E; Jonot, Odile; Giraud, Tatiana

2010-01-01

337

Glacial Refugia in Pathogens: European Genetic Structure of Anther Smut Pathogens on Silene latifolia and Silene dioica  

PubMed Central

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

Vercken, Elodie; Fontaine, Michael C.; Gladieux, Pierre; Hood, Michael E.; Jonot, Odile; Giraud, Tatiana

2010-01-01

338

Influenza virus activates inflammasomes through intracellular M2 channel  

PubMed Central

Influenza virus, a negative stranded RNA virus causing severe illness in humans and animals, stimulates the inflammasome through the NOD-like receptor (NLR), NLRP3. However, the mechanism by which influenza virus activates the NLRP3 inflammasome is unknown. Here, we show that the influenza virus M2 protein, a proton-selective ion channel important in viral pathogenesis, stimulates the NLRP3 inflammasome pathway. M2 channel activity was required for influenza activation of inflammasomes, and was sufficient to activate inflammasomes in primed macrophages and dendritic cells. M2-induced inflammasome activation required its localization to Golgi and was dependent on pH gradient. Our results reveal a mechanism by which influenza virus infection activates inflammasomes, and identifies the sensing of disturbances in intracellular ionic concentrations as a novel pathogen recognition pathway. PMID:20383149

Ichinohe, Takeshi; Pang, Iris Kok-shuen; Iwasaki, Akiko

2010-01-01

339

Studies of polyamine metabolism in obligately alkalophilic Bacillus alcalophilus that grow at pH 11  

SciTech Connect

Bacillus alcalophilus, an obligately alkalophilic bacterium, grow at pH 11 with an intracellular pH greater than 9.5. Polyamines are positively charged at physiological pH, but less than 50% of polyamines will be charged at pH 9.5 and above. In view of the importance of polycationic nature of polyamines in their physiological functions, it is of interest to study the polyamine metabolism in B. alcalophilus, an unusual organism that grow at very high pH. Spermidine is the major polyamine in this organism, accounts for more than 90% of total polyamine. The level of spermidine fluctuates between 10 to 30 nmol per mg protein during growth. In contrast, putrescine and spermine levels stay constant during entire period of growth. No ornithine decarboxylase (DC) activity can be detected in B. alcalophilus under all conditions examined. When (/sup 3/H)arginine was added to the bacterial culture, the distribution of radioactivity in polyamine pool was 3% for putrescine, 94% for spermidine, and 3% for spermine, suggesting the presence of arginine pathway for polyamine biosynthesis. B. alcalophilus appears to possess a polyamine transport system that is Na/sup +/-dependent. Putrescine uptake in B. alcalophilus is sensitive to the inhibition of gramicidine S (10 ..mu..M) and valinomycin (2..mu..M).

Cheng, S.; Chen, K.Y.

1987-05-01

340

Multiple ecto-nucleoside triphosphate diphosphohydrolases facilitate intracellular replication of Legionella pneumophila.  

PubMed

Legionella pneumophila is an opportunistic pathogen that replicates within alveolar macrophages resulting in the onset of severe atypical pneumonia. Previously we have identified Lpg1905, a eukaryotic-type ecto-NTPDase (nucleoside triphosphate diphosphohydrolase) from L. pneumophila that was required for optimal intracellular replication and virulence in a mouse lung infection model. In the present study, we characterized the activity of a second eukaryotic-type NTPDase, Lpg0971, from L. pneumophila. We observed that recombinant Lpg0971 hydrolysed only ATP and exhibited divalent cation preference for manganese (II) ions. Similar to lpg1905, an lpg0971 mutant carrying the plasmid pMIP was attenuated in a mouse lung infection model and impaired for replication in human macrophages and amoebae. Increased trafficking of the LCV (Legionella-containing vacuole) to a LAMP-1 (lysosome-associated membrane protein-1)-positive compartment was observed for both the lpg1905 and lpg0971 mutants carrying pMIP. Complementation with either lpg1905 or lpg0971 restored intracellular replication, suggesting that a minimum level of ATPase activity was required for this function. A double lpg1905/0971 mutant was not more impaired for intracellular replication than the single mutants and complementation of the double mutant with lpg0971, but not lpg1905, restored intracellular replication. This suggested that although the NTPDases have overlapping activities they have distinct functions. Unlike many eukaryotic-type proteins from L. pneumophila, neither Lpg1905 nor Lpg0971 were translocated into the host cell by the Dot/Icm (defective in organelle trafficking/intracellular multiplication) type IV secretion system. Overall our data suggest that the ability of L. pneumophila to replicate in eukaryotic cells relies in part on the ability of the pathogen to hydrolyse ATP within an intracellular compartment. PMID:24957128

Riedmaier, Patrice; Sansom, Fiona M; Sofian, Trifina; Beddoe, Travis; Schuelein, Ralf; Newton, Hayley J; Hartland, Elizabeth L

2014-09-01

341

Rac and Rab GTPases dual effector Nischarin regulates vesicle maturation to facilitate survival of intracellular bacteria.  

PubMed

The intracellular pathogenic bacterium Salmonella enterica serovar typhimurium (Salmonella) relies on acidification of the Salmonella-containing vacuole (SCV) for survival inside host cells. The transport and fusion of membrane-bound compartments in a cell is regulated by small GTPases, including Rac and members of the Rab GTPase family, and their effector proteins. However, the role of these components in survival of intracellular pathogens is not completely understood. Here, we identify Nischarin as a novel dual effector that can interact with members of Rac and Rab GTPase (Rab4, Rab14 and Rab9) families at different endosomal compartments. Nischarin interacts with GTP-bound Rab14 and PI(3)P to direct the maturation of early endosomes to Rab9/CD63-containing late endosomes. Nischarin is recruited to the SCV in a Rab14-dependent manner and enhances acidification of the SCV. Depletion of Nischarin or the Nischarin binding partners--Rac1, Rab14 and Rab9 GTPases--reduced the intracellular growth of Salmonella. Thus, interaction of Nischarin with GTPases may regulate maturation and subsequent acidification of vacuoles produced after phagocytosis of pathogens. PMID:23386062

Kuijl, Coenraad; Pilli, Manohar; Alahari, Suresh K; Janssen, Hans; Khoo, Poh-Sim; Ervin, Karen E; Calero, Monica; Jonnalagadda, Sobhanaditya; Scheller, Richard H; Neefjes, Jacques; Junutula, Jagath R

2013-03-01

342

Rac and Rab GTPases dual effector Nischarin regulates vesicle maturation to facilitate survival of intracellular bacteria  

PubMed Central

The intracellular pathogenic bacterium Salmonella enterica serovar typhimurium (Salmonella) relies on acidification of the Salmonella-containing vacuole (SCV) for survival inside host cells. The transport and fusion of membrane-bound compartments in a cell is regulated by small GTPases, including Rac and members of the Rab GTPase family, and their effector proteins. However, the role of these components in survival of intracellular pathogens is not completely understood. Here, we identify Nischarin as a novel dual effector that can interact with members of Rac and Rab GTPase (Rab4, Rab14 and Rab9) families at different endosomal compartments. Nischarin interacts with GTP-bound Rab14 and PI(3)P to direct the maturation of early endosomes to Rab9/CD63-containing late endosomes. Nischarin is recruited to the SCV in a Rab14-dependent manner and enhances acidification of the SCV. Depletion of Nischarin or the Nischarin binding partners—Rac1, Rab14 and Rab9 GTPases—reduced the intracellular growth of Salmonella. Thus, interaction of Nischarin with GTPases may regulate maturation and subsequent acidification of vacuoles produced after phagocytosis of pathogens. PMID:23386062

Kuijl, Coenraad; Pilli, Manohar; Alahari, Suresh K; Janssen, Hans; Khoo, Poh-Sim; Ervin, Karen E; Calero, Monica; Jonnalagadda, Sobhanaditya; Scheller, Richard H; Neefjes, Jacques; Junutula, Jagath R

2013-01-01

343

29 CFR 37.20 - What is a grant applicant's obligation to provide a written assurance?  

...2014-07-01 2013-07-01 true What is a grant applicant's obligation to...Obligations of Recipients § 37.20 What is a grant applicant's obligation to...United States on the basis of race, color, religion, sex, national origin, age,...

2014-07-01

344

29 CFR 37.20 - What is a grant applicant's obligation to provide a written assurance?  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false What is a grant applicant's obligation to...Obligations of Recipients § 37.20 What is a grant applicant's obligation to...United States on the basis of race, color, religion, sex, national origin, age,...

2013-07-01

345

29 CFR 37.20 - What is a grant applicant's obligation to provide a written assurance?  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false What is a grant applicant's obligation to...Obligations of Recipients § 37.20 What is a grant applicant's obligation to...United States on the basis of race, color, religion, sex, national origin, age,...

2011-07-01

346

29 CFR 37.20 - What is a grant applicant's obligation to provide a written assurance?  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false What is a grant applicant's obligation to...Obligations of Recipients § 37.20 What is a grant applicant's obligation to...United States on the basis of race, color, religion, sex, national origin, age,...

2012-07-01

347

29 CFR 37.20 - What is a grant applicant's obligation to provide a written assurance?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 true What is a grant applicant's obligation to...Obligations of Recipients § 37.20 What is a grant applicant's obligation to...United States on the basis of race, color, religion, sex, national origin, age,...

2010-07-01

348

20 CFR 703.115 - Discharge by the carrier of obligations and duties of employer.  

Code of Federal Regulations, 2010 CFR

...carrier of obligations and duties of employer. 703...carrier of obligations and duties of employer. Every obligation and duty in respect of payment...and other treatment and care, the payment or...employer to the district director and to the...

2010-04-01

349

30 CFR 243.8 - When will MMS suspend my obligation to comply with an order?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false When will MMS suspend my obligation to comply with an...General Provisions § 243.8 When will MMS suspend my obligation to comply with an...require payment of a specified amount, MMS will suspend your obligation to comply...

2010-07-01

350

A Method for Functional Trans-Complementation of Intracellular Francisella tularensis  

PubMed Central

Francisella tularensis is a highly infectious bacterial pathogen that invades and replicates within numerous host cell types. After uptake, F. tularensis bacteria escape the phagosome, replicate within the cytosol, and suppress cytokine responses. However, the mechanisms employed by F. tularensis to thrive within host cells are mostly unknown. Potential F. tularensis mutants involved in host-pathogen interactions are typically discovered by negative selection screens for intracellular replication or virulence. Mutants that fulfill these criteria fall into two categories: mutants with intrinsic intracellular growth defects and mutants that fail to modify detrimental host cell processes. It is often difficult and time consuming to discriminate between these two possibilities. We devised a method to functionally trans-complement and thus identify mutants that fail to modify the host response. In this assay, host cells are consistently and reproducibly infected with two different F. tularensis strains by physically tethering the bacteria to antibody-coated beads. To examine the efficacy of this protocol, we tested phagosomal escape, cytokine suppression, and intracellular replication for F. tularensis ?ripA and ?pdpC. ?ripA has an intracellular growth defect that is likely due to an intrinsic defect and fails to suppress IL-1? secretion. In the co-infection model, ?ripA was unable to replicate in the host cell when wild-type bacteria infected the same cell, but cytokine suppression was rescued. Therefore, ?ripA intracellular growth is due to an intrinsic bacterial defect while cytokine secretion results from a failed host-pathogen interaction. Likewise, ?pdpC is deficient for phagosomal escape, intracellular survival and suppression of IL-1? secretion. Wild-type bacteria that entered through the same phagosome as ?pdpC rescued all of these phenotypes, indicating that ?pdpC failed to properly manipulate the host. In summary, functional trans-complementation using bead-bound bacteria co-infections is a method to rapidly identify mutants that fail to modify a host response. Francisella tularensis is a facultative intracellular bacterial pathogen and is the causative agent of the disease tularemia. F. tularensis enters host cells through phagocytosis, escapes the phagosome, and replicates in the host cell cytosol while suppressing cytokine secretion [1]–[4]. Although substantial progress has been made in understanding the intracellular life cycle of F. tularensis, the F. tularensis proteins responsible for manipulating many host cell pathways are unknown. Identifying novel host-pathogen effector proteins is difficult because there is no rapid method to reliably distinguish between bacterial proteins that modify host processes and proteins that are involved in bacterial processes that are required for the bacteria to survive or replicate in the intracellular environment. The ability to identify mutants that are deficient for host-pathogen interactions is important because it can aid in prioritizing the investigation of genes of interest and in downstream experimental design. Moreover, certain mutant phenotypes, such as decreased phagosomal escape, hinder investigation of other potential phenotypes. A method to specifically complement these phenotypes would allow for further characterizations of certain F. tularensis mutants. Thus we sought to develop a method to easily identify and functionally complement mutants that are deficient for interactions with the host. PMID:24505427

Steele, Shaun; Taft-Benz, Sharon; Kawula, Thomas

2014-01-01

351

Bordetella pertussis entry into respiratory epithelial cells and intracellular survival.  

PubMed

Bordetella pertussis is the causative agent of pertussis, aka whooping cough. Although generally considered an extracellular pathogen, this bacterium has been found inside respiratory epithelial cells, which might represent a survival strategy inside the host. Relatively little is known, however, about the mechanism of internalization and the fate of B. pertussis inside the epithelia. We show here that B. pertussis is able to enter those cells by a mechanism dependent on microtubule assembly, lipid raft integrity, and the activation of a tyrosine-kinase-mediated signaling. Once inside the cell, a significant proportion of the intracellular bacteria evade phagolysosomal fusion and remain viable in nonacidic lysosome-associated membrane-protein-1-negative compartments. In addition, intracellular B. pertussis was found able to repopulate the extracellular environment after complete elimination of the extracellular bacteria with polymyxin B. Taken together, these data suggest that B. pertussis is able to survive within respiratory epithelial cells and by this means potentially contribute to host immune system evasion. PMID:23893966

Lamberti, Yanina; Gorgojo, Juan; Massillo, Cintia; Rodriguez, Maria E

2013-12-01

352

Federal Obligations for Research by Agency and Detailed Field of Science and Engineering: Fiscal Years 1970-2002  

NSF Publications Database

... Federal Obligations for Research by Agency and Detailed Field of Science and Engineering: Fiscal ... Format Federal Obligations for Research by Agency and Detailed Field of Science and Engineering ...

353

Legionella pneumophilaRequires Polyamines for Optimal Intracellular Growth ?  

PubMed Central

The Gram-negative intracellular pathogen Legionella pneumophilareplicates in a membrane-bound compartment known as the Legionella-containing vacuole (LCV), into which it abundantly releases its chaperonin, HtpB. To determine whether HtpB remains within the LCV or reaches the host cell cytoplasm, we infected U937 human macrophages and CHO cells with L. pneumophilaexpressing a translocation reporter consisting of the Bordetella pertussisadenylate cyclase fused to HtpB. These infections led to increased cyclic AMP levels, suggesting that HtpB reaches the host cell cytoplasm. To identify potential functions of cytoplasmic HtpB, we expressed it in the yeast Saccharomyces cerevisiae, where HtpB induced pseudohyphal growth. A yeast-two-hybrid screen showed that HtpB interacted with S-adenosylmethionine decarboxylase (SAMDC), an essential yeast enzyme (encoded by SPE2) that is required for polyamine biosynthesis. Increasing the copy number of SPE2induced pseudohyphal growth in S. cerevisiae; thus, we speculated that (i) HtpB induces pseudohyphal growth by activating polyamine synthesis and (ii) L. pneumophilamay require exogenous polyamines for growth. A pharmacological inhibitor of SAMDC significantly reduced L. pneumophilareplication in L929 mouse cells and U937 macrophages, whereas exogenously added polyamines moderately favored intracellular growth, confirming that polyamines and host SAMDC activity promote L. pneumophilaproliferation. Bioinformatic analysis revealed that most known enzymes required for polyamine biosynthesis in bacteria (including SAMDC) are absent in L. pneumophila, further suggesting a need for exogenous polyamines. We hypothesize that HtpB may function to ensure a supply of polyamines in host cells, which are required for the optimal intracellular growth of L. pneumophila. PMID:21742865

Nasrallah, Gheyath K.; Riveroll, Angela L.; Chong, Audrey; Murray, Lois E.; Lewis, P. Jeffrey; Garduno, Rafael A.

2011-01-01

354

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

355

Duty of care is underpinned by a range of obligations.  

PubMed

The courts have long established that nurses are in a duty situation and owe a duty of care to their patients (Kent v Griffiths [2001]). Traditionally, the profession set the standard of care and nurses were required to act in accordance with a practice accepted by a responsible body of their peers (Bolam v Friern HMC [1957]).The introduction of the Human Rights Act 1998 gave rise to a positive obligation on government to ensure that laws, policies and procedures are in place to protect violations of human rights. Nurses must now inform their practice with relevant statute law, common law and professional standards in order to properly discharge their duty of care. Richard Griffith considers the law that now underpins a nurse's duty of care and uses a recent report from the Health Service Ombudsman for England to illustrate the obligations that underpin the nurse-patient relationship. PMID:24809155

Griffith, Richard

356

To what do we have moral obligations and why? II.  

PubMed

Following up on his 1 June 1985 article on moral obligations to living human beings versus other sentient beings, Gillon focuses on arguments for and against prohuman "speciesism," the claim that "viability" is a justifiable criterion for differentiating between humans that may be killed and those that may not, and claims that "personhood" is a morally relevant differentiating concept. He discusses the positions taken by Peter Singer and Dame Mary Warnock on "speciesism," and the theories of such philosphers as John Locke, Immanuel Kant, and Michael Tooley regarding the essence of personhood. He sees no solid basis for grounding the scope of moral obligations on simple sentience, membership in the human species, or technical differentia such as viability, and concludes that medical ethics still suffers from the lack of an adequate theory on which to base a right to life. PMID:3924233

Gillon, R

1985-06-01

357

Clinical findings in obligate carriers of type I Usher syndrome  

SciTech Connect

Seventeen obligate carriers from nine families with autosomal recessive Usher syndrome type I underwent otological, audiological, vestibular, and ophthalmological examination in order to identify possible manifestations of heterozygosity. Linkage studies were performed and six families showed linkage to chromosome region 11q13.5 while 3 families have so far failed to show linkage to the candidate regions. Eight obligate carriers had an abnormal puretone audiogram. Two different audiometric patterns could be distinguished when hearing loss was corrected for age and sex. Four carriers (24%) had significant sensorineural hearing loss (SNHL) which increased at higher frequencies. The other 13 carriers had SNHL of about 10 dB at 0.25 and 0.5 kHz, but less at higher frequencies. Vestibular findings were generally normal. Electrooculography demonstrated a significant lower mean light peak/dark trough ratio in Usher type I carriers compared to normal control individuals. The methods used in this study were found not to be specific enough to clinically identify carriers of Usher type I syndrome. Nevertheless it is remarkable that a number of obligate carriers showed significant audiological and ophthalmological abnormalities. 29 refs., 1 fig., 3 tabs.

Wagenaar, M.; Rahe, B. ter; Aarem, A. van; Huygen, P.; Admiraal, R. [University Hospital Nijmegen (Netherlands)] [and others

1995-11-20

358

Floral scents repel facultative flower visitors, but attract obligate ones  

PubMed Central

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

Junker, Robert R.; Blüthgen, Nico

2010-01-01

359

Kant's assessment of motivation in the fulfillment of social obligations.  

PubMed

This paper explores the motivations of physicians who promote the health of their communities through the fulfillment of social obligations beyond the boundaries of their own patients. Based on the assumption that physicians do not have social obligations, this paper looks at the normative, motivational question, namely "How should physicians be motivated to fulfill social obligations?" The paper traces the Kantian view of morality and motivation. The distinctions between required, merely permissible, and forbidden actions is drawn. Furthermore, Kant's view that required actions done in accordance with duty are of no moral worth is critiqued from three stand points. First, it is argued that just because motivations outside of Kantian-based duty are not as good, it does not follow that these motivations are of no moral worth. Second, it is argued that there are some motivations behind required actions that are clearly better than other motivations. Third, it is argued that required actions done in accordance with duty are clearly better than those actions done without relevance to duty. The paper concludes that many required actions done in accordance with duty are performed from motivations that do have moral worth. PMID:17146908

Knupp, Jackie

2006-01-01

360

Stochastic resonance in an intracellular genetic perceptron  

NASA Astrophysics Data System (ADS)

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.

Bates, Russell; Blyuss, Oleg; Zaikin, Alexey

2014-03-01

361

Detection of Intracellular Bacterial Communities in Human Urinary Tract Infection  

PubMed Central

Background Urinary tract infections (UTIs) are one of the most common bacterial infections and are predominantly caused by uropathogenic Escherichia coli (UPEC). While UTIs are typically considered extracellular infections, it has been recently demonstrated that UPEC bind to, invade, and replicate within the murine bladder urothelium to form intracellular bacterial communities (IBCs). These IBCs dissociate and bacteria flux out of bladder facet cells, some with filamentous morphology, and ultimately establish quiescent intracellular reservoirs that can seed recurrent infection. This IBC pathogenic cycle has not yet been investigated in humans. In this study we sought to determine whether evidence of an IBC pathway could be found in urine specimens from women with acute UTI. Methods and Findings We collected midstream, clean-catch urine specimens from 80 young healthy women with acute uncomplicated cystitis and 20 asymptomatic women with a history of UTI. Investigators were blinded to culture results and clinical history. Samples were analyzed by light microscopy, immunofluorescence, and electron microscopy for evidence of exfoliated IBCs and filamentous bacteria. Evidence of IBCs was found in 14 of 80 (18%) urines from women with UTI. Filamentous bacteria were found in 33 of 80 (41%) urines from women with UTI. None of the 20 urines from the asymptomatic comparative group showed evidence of IBCs or filaments. Filamentous bacteria were present in all 14 of the urines with IBCs compared to 19 (29%) of 66 samples with no evidence of IBCs (p < 0.001). Of 65 urines from patients with E. coli infections, 14 (22%) had evidence of IBCs and 29 (45%) had filamentous bacteria, while none of the gram-positive infections had IBCs or filamentous bacteria. Conclusions The presence of exfoliated IBCs and filamentous bacteria in the urines of women with acute cystitis suggests that the IBC pathogenic pathway characterized in the murine model may occur in humans. The findings support the occurrence of an intracellular bacterial niche in some women with cystitis that may have important implications for UTI recurrence and treatment. PMID:18092884

Rosen, David A; Hooton, Thomas M; Stamm, Walter E; Humphrey, Peter A; Hultgren, Scott J

2007-01-01

362

Evolution of microbial pathogens.  

PubMed Central

Various genetic mechanisms including point mutations, genetic rearrangements and lateral gene transfer processes contribute to the evolution of microbes. Long-term processes leading to the development of new species or subspecies are termed macroevolution, and short-term developments, which occur during days or weeks, are considered as microevolution. Both processes, macro- and microevolution need horizontal gene transfer, which is particularly important for the development of pathogenic microorganisms. Plasmids, bacteriophages and so-called pathogenicity islands (PAIs) play a crucial role in the evolution of pathogens. During microevolution, genome variability of pathogenic microbes leads to new phenotypes, which play an important role in the acute development of an infectious disease. Infections due to Staphylococcus epidermidis, Candida albicans and Escherichia coli will be described with special emphasis on processes of microevolution. In contrast, the development of PAIs is a process involved in macroevolution. PAIs are especially important in processes leading to new pathotypes or even species. In this review, particular attention will be given to the fact that the evolution of pathogenic microbes can be considered as a specific example for microbial evolution in general. PMID:10874741

Morschhauser, J; Kohler, G; Ziebuhr, W; Blum-Oehler, G; Dobrindt, U; Hacker, J

2000-01-01

363

A bacterial siren song: intimate interactions between neutrophils and pathogenic Neisseria  

PubMed Central

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

Criss, Alison K.; Seifert, H. Steven

2012-01-01

364

Pathogens: raft hijackers.  

PubMed

Throughout evolution, organisms have developed immune-surveillance networks to protect themselves from potential pathogens. At the cellular level, the signalling events that regulate these defensive responses take place in membrane rafts--dynamic microdomains that are enriched in cholesterol and glycosphingolipids--that facilitate many protein-protein and lipid-protein interactions at the cell surface. Pathogens have evolved many strategies to ensure their own survival and to evade the host immune system, in some cases by hijacking rafts. However, understanding the means by which pathogens exploit rafts might lead to new therapeutic strategies to prevent or alleviate certain infectious diseases, such as those caused by HIV-1 or Ebola virus. PMID:12876558

Mañes, Santos; del Real, Gustavo; Martínez-A, Carlos

2003-07-01

365

Neopolyploidy and pathogen resistance  

PubMed Central

Despite the well-documented historical importance of polyploidy, the mechanisms responsible for the establishment and evolutionary success of novel polyploid lineages remain unresolved. One possibility, which has not been previously evaluated theoretically, is that novel polyploid lineages are initially more resistant to pathogens than the diploid progenitor species. Here, we explore this possibility by developing and analysing mathematical models of interactions between newly formed polyploid lineages and their pathogens. We find that for the genetic mechanisms of pathogen resistance with the best empirical support, newly formed polyploid populations of hosts are expected to be more resistant than their diploid progenitors. This effect can be quite strong and, in the case of perennial species with recurrent polyploid formation, may last indefinitely, potentially providing a general explanation for the successful establishment of novel polyploid lineages. PMID:17686733

Oswald, Benjamin P; Nuismer, Scott L

2007-01-01

366

Salmonella typhi: from a human pathogen to a vaccine vector.  

PubMed

Salmonella (S.) typhi is an important intracellular pathogen. Among the more than 2,300 closely-related Salmonella serovars bacteria recognized, S. typhi is the only one that is pathogenic exclusively for humans, in whom it causes typhoid or enteric fever. The pathogen has been around for many years and many studies have been done in an effort to combat it. Molecular and biologic features of S. typhi and host factors and immune responses involved in Salmonella invasion have been extensively studies. Vaccines that have been developed most notably are Vi polysaccharide and Ty21a. However, as the results show, there is still a long way to go. It is also shown that multi-drug resistance has occurred to the few available antibiotics. More and more studies have shown that Salmonella can be used as a vaccine vector carrying antigens of other pathogens. This has been promising in that the immune system can be elicited in response to both the Salmonella bacteria and the antigen of the pathogen in question. This review aims to highlight some of the milestones attained in the fight against the disease from the time S. typhi was seen as a pathogen causing typhoid fever to the use of Salmonella as a vaccine vector. PMID:18445338

Zhang, Xiao-Lian; Jeza, Victor Tunje; Pan, Qin

2008-04-01

367

Bacterial pathogen manipulation of host membrane trafficking.  

PubMed

Pathogens use a vast number of strategies to alter host membrane dynamics. Targeting the host membrane machinery is important for the survival and pathogenesis of several extracellular, vacuolar, and cytosolic bacteria. Membrane manipulation promotes bacterial replication while suppressing host responses, allowing the bacterium to thrive in a hostile environment. This review provides a comprehensive summary of various strategies used by both extracellular and intracellular bacteria to hijack host membrane trafficking machinery. We start with mechanisms used by bacteria to alter the plasma membrane, delve into the hijacking of various vesicle trafficking pathways, and conclude by summarizing bacterial adaptation to host immune responses. Understanding bacterial manipulation of host membrane trafficking provides insights into bacterial pathogenesis and uncovers the molecular mechanisms behind various processes within a eukaryotic cell. PMID:25103867

Asrat, Seblewongel; de Jesús, Dennise A; Hempstead, Andrew D; Ramabhadran, Vinay; Isberg, Ralph R

2014-10-11

368

Rapid Detection of Pathogens  

Microsoft Academic Search

Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents.

David Perlin

2005-01-01

369

Intracellular Vibrio parahaemolyticus Escapes the Vacuole and Establishes a Replicative Niche in the Cytosol of Epithelial Cells  

PubMed Central

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

de Souza Santos, Marcela

2014-01-01

370

The Brucella suis genome reveals fundamental similarities between animal and plant pathogens and symbionts  

Microsoft Academic Search

The 3.31-Mb genome sequence of the intracellular pathogen and potential bioterrorism agent, Brucella suis, was determined. Comparison of B. suis with Brucella melitensis has defined a finite set of differences that could be responsible for the differences in virulence and host preference between these organisms, and indicates that phage have played a significant role in their divergence. Analysis of the

Ian T. Paulsen; Rekha Seshadri; Karen E. Nelson; John F. Heidelberg; Timothy D. Read; Robert J. Dodson; Lowell Umayam; Lauren M. Brinkac; Maureen J. Beanan; Sean C. Daugherty; Robert T. Deboy; A. Scott Durkin; James F. Kolonay; Ramana Madupu; William C. Nelson; Bola Ayodeji; Margaret Kraul; Jyoti Shetty; Joel Malek; Susan E. van Aken; Steven Riedmuller; Herve Tettelin; Steven R. Gill; Owen White; Steven L. Salzberg; David L. Hoover; Luther E. Lindler; Shirley M. Halling; Stephen M. Boyle; Claire M. Fraser

2002-01-01

371

Comparison of the 'Ca. Liberibacter asiaticus' Genome Adapted for an Intracellular Lifestyle with Other Members of the Rhizobiales  

PubMed Central

An intracellular plant pathogen ‘Candidatus Liberibacter asiaticus,’ a member of the Rhizobiales, is related to Sinorhizobium meliloti, Bradyrhizobium japonicum, nitrogen fixing endosymbionts, Agrobacterium tumefaciens, a plant pathogen, and Bartonella henselae, an intracellular mammalian pathogen. Whole chromosome comparisons identified at least 50 clusters of conserved orthologous genes found on the chromosomes of all five metabolically diverse species. The intracellular pathogens ‘Ca. Liberibacter asiaticus’ and Bartonella henselae have genomes drastically reduced in gene content and size as well as a relatively low content of guanine and cytosine. Codon and amino acid preferences that emphasize low guanosine and cytosine usage are globally employed in these genomes, including within regions of microsynteny and within signature sequences of orthologous proteins. The length of orthologous proteins is generally conserved, but not their isoelectric points, consistent with extensive amino acid substitutions to accommodate selection for low GC content. The ‘Ca. Liberibacter asiaticus’ genome apparently has all of the genes required for DNA replication present in Sinorhizobium meliloti except it has only two, rather than three RNaseH genes. The gene set required for DNA repair has only one rather than ten DNA ligases found in Sinorhizobium meliloti, and the DNA PolI of ‘Ca. Liberibacter asiaticus’ lacks domains needed for excision repair. Thus the ability of ‘Ca. Liberibacter asiaticus’ to repair mutations in its genome may be impaired. Both ‘Ca. Liberibacter asiaticus and Bartonella henselae lack enzymes needed for the metabolism of purines and pyrimidines, which must therefore be obtained from the host. The ‘Ca. Liberibacter asiaticus’ genome also has a greatly reduced set of sigma factors used to control transcription, and lacks sigma factors 24, 28 and 38. The ‘Ca. Liberibacter asiaticus’ genome has all of the hallmarks of a reduced genome of a pathogen adapted to an intracellular lifestyle. PMID:21876745

Hartung, John S.; Shao, Jonathan; Kuykendall, L. David

2011-01-01

372

GABAAergic stimulation modulates intracellular protein arginine methylation.  

PubMed

Changes in cytoplasmic pH are known to regulate diverse cellular processes and influence neuronal activities. In neurons, the intracellular alkalization is shown to occur after stimulating several channels and receptors. For example, it has previously demonstrated in P19 neurons that a sustained intracellular alkalinization can be mediated by the Na(+)/H(+) antiporter. In addition, the benzodiazepine binding subtypes of the ?-amino butyric acid type A (GABAA) receptor mediate a transient intracellular alkalinization when they are stimulated. Because the activities of many enzymes are sensitive to pH shift, here we investigate the effects of intracellular pH modulation resulted from stimulating GABAA receptor on the protein arginine methyltransferases (PRMT) activities. We show that the major benzodiazepine subtype (2?1, 2?2, 1?2) is constitutively expressed in both undifferentiated P19 cells and retinoic acid (RA) differentiated P19 neurons. Furthermore stimulation with diazepam and, diazepam plus muscimol produce an intracellular alkalinization that can be detected ex vivo with the fluorescence dye. The alkalinization results in significant perturbation in protein arginine methylation activity as measured in methylation assays with specific protein substrates. Altered protein arginine methylation is also observed when cells are treated with the GABAA agonist muscimol but not an antagonist, bicuculline. These data suggest that pH-dependent and pH-independent methylation pathways can be activated by GABAAergic stimulation, which we verified using hippocampal slice preparations from a mouse model of fragile X syndrome. PMID:24793772

Denman, Robert B; Xie, Wen; Merz, George; Sung, Ying-Ju

2014-06-20

373

Host-to-Pathogen Gene Transfer Facilitated Infection of Insects by a Pathogenic Fungus  

PubMed Central

Metarhizium robertsii is a plant root colonizing fungus that is also an insect pathogen. Its entomopathogenicity is a characteristic that was acquired during evolution from a plant endophyte ancestor. This transition provides a novel perspective on how new functional mechanisms important for host switching and virulence have evolved. From a random T-DNA insertion library, we obtained a pathogenicity defective mutant that resulted from the disruption of a sterol carrier gene (Mr-npc2a). Phylogenetic analysis revealed that Metarhizium acquired Mr-npc2a from an insect by horizontal gene transfer (HGT). Mr-NPC2a binds to cholesterol, an animal sterol, rather than the fungal sterol ergosterol, indicating it retains the specificity of insect NPC2 proteins. Mr-NPC2a is an intracellular protein and is exclusively expressed in the hemolymph of living insects. The disruption of Mr-npc2a reduced the amount of sterol in cell membranes of the yeast-like hyphal bodies that facilitate dispersal in the host body. These were consequently more susceptible to insect immune responses than the wild type. Transgenic expression of Mr-NPC2a increased the virulence of Beauveria bassiana, an endophytic insect-pathogenic fungus that lacks a Mr-NPC2a homolog. PMID:24722668

Zhao, Hong; Xu, Chuan; Lu, Hsiao-Ling; Chen, Xiaoxuan; St. Leger, Raymond J.; Fang, Weiguo

2014-01-01

374

WATERBORNE PATHOGENS IN URBAN WATERSHEDS  

EPA Science Inventory

Pathogens are microorganisms that can cause sickness or even death. A serious concern for managers of water resources, pathogens in the urban environment easily enter waters through a number of pathways, including discharge of inadequately treated sewage, stormwater runoff, combi...

375

The evolutionary pathway to obligate scavenging in Gyps vultures.  

PubMed

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

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

2011-01-01

376

The Evolutionary Pathway to Obligate Scavenging in Gyps Vultures  

PubMed Central

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

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

2011-01-01

377

Intracellular trafficking of P-glycoprotein.  

PubMed

Overexpression of P-glycoprotein (P-gp) is a major cause of multidrug resistance in cancer. P-gp is mainly localized in the plasma membrane and can efflux structurally and chemically unrelated substrates, including anticancer drugs. P-gp is also localized in intracellular compartments, such as endoplasmic reticulum (ER), Golgi, endosomes and lysosomes, and cycles between endosomal compartments and the plasma membrane in a microtubular-actin dependent manner. Intracellular trafficking pathways for P-gp and participation of different Rab proteins depend on cellular polarization and choice of primary culture, cell line or neoplasm. Interruption of P-gp trafficking to the plasma membrane increases intracellular P-gp accumulation and anticancer drug levels, suggesting a potential approach to overcome P-gp-mediated multidrug resistance in cancer. PMID:22212176

Fu, Dong; Arias, Irwin M

2012-03-01

378

Potential lactoferrin activity against pathogenic viruses.  

PubMed

Lactoferrin (LF) is an 80-kDa globular glycoprotein with high affinity for metal ions, particularly for iron. This protein possesses many biological functions, including the binding and release of iron and serves as one of the important components of the innate immune system, where it acts as a potent inhibitor of several pathogens. LF has efficacious antibacterial and antiviral activities against a wide range of Gram-positive and Gram-negative bacteria and against both naked and enveloped DNA and RNA viruses. In its antiviral pursuit, LF acts predominantly at the acute phase of the viral infection or even at the intracellular stage, as in hepatitis C virus infection. LF inhibits the entry of viral particles into host cells, either by direct attachment to the viral particles or by blocking their cellular receptors. This wide range of activities may be attributed to the capacity of LF to bind iron and its ability to interfere with the cellular receptors of both hosts and pathogenic microbes. PMID:25282173

Redwan, Elrashdy M; Uversky, Vladimir N; El-Fakharany, Esmail M; Al-Mehdar, Hussein

2014-10-01

379

Olive knot and its pathogens  

Microsoft Academic Search

Olive knot, caused by a pathogen or pathogens within the group of bacterial pathogens currently known as Pseudomonas savastanoi, is described. The ecology, transmission and methods of control of the pathogens are discussed. Strategies to minimise the\\u000a effects of infection are recommended and these depend on attention to specific details in programs for pruning, irrigation\\u000a and use of fertiliser. Introduction

J. M. Young

2004-01-01

380

Multiplex detection of agricultural pathogens  

DOEpatents

Described are kits and methods useful for detection of agricultural pathogens in a sample. Genomic sequence information from agricultural pathogens was analyzed to identify signature sequences, e.g., polynucleotide sequences useful for confirming the presence or absence of a pathogen in a sample. Primer and probe sets were designed and optimized for use in a PCR based, multiplexed Luminex assay and/or an array assay to successfully identify the presence or absence of pathogens in a sample.

Siezak, Thomas R.; Gardner, Shea; Torres, Clinton; Vitalis, Elizabeth; Lenhoff, Raymond J.

2013-01-15

381

Endosomal escape: a bottleneck in intracellular delivery.  

PubMed

With advances in therapeutic science, apart from drugs, newer bioactive moieties like oligonucleotides, proteins, peptides, enzymes and antibodies are constantly being introduced for the betterment of therapeutic efficacy. These moieties have intracellular components of the cells like cytoplasm and nucleus as one of their pharmacological sites for exhibiting therapeutic activity. Despite their promising efficacy, their intracellular bioavailability has been critically hampered leading to failure in the treatment of numerous diseases and disorders. The endosomal uptake pathway is known to be a rate-limiting barrier for such systems. Bioactive molecules get trapped in the endosomal vesicles and degraded in the lysosomal compartment, necessitating the need for effective strategies that facilitate the endosomal escape and enhance the cytosolic bioavailability of bioactives. Microbes like viruses and bacteria have developed their innate mechanistic tactics to translocate their genome and toxins by efficiently penetrating the host cell membrane. Understanding this mechanism and exploring it further for intracellular delivery has opened new avenues to surmount the endosomal barrier. These strategies include membrane fusion, pore formation and proton sponge effects. On the other hand, progress in designing a novel smart polymeric carrier system that triggers endosomal escape by undergoing modulations in the intracellular milieu has further led to an improvement in intracellular delivery. These comprise pH, enzyme and temperature-induced modulators, synthetic cationic lipids and photo-induced physical disruption. Each of the aforementioned strategies has its own unique mechanism to escape the endosome. This review recapitulates the numerous strategies designed to surmount the bottleneck of endosomal escape and thereby achieve successful intracellular uptake of bioactives. PMID:24730275

Shete, Harshad K; Prabhu, Rashmi H; Patravale, Vandana B

2014-01-01

382

Chitosan against cutaneous pathogens.  

PubMed

Propionibacterium acnes and Staphylococcus aureus are cutaneous pathogens that have become increasingly resistant to antibiotics. We sought to determine if chitosan, a polymer of deacetylated chitin, could be used as a potential treatment against these bacteria. We found that higher molecular weight chitosan had superior antimicrobial properties compared to lower molecular weights, and that this activity occurred in a pH dependent manner. Electron and fluorescence microscopy revealed that chitosan forms aggregates and binds to the surface of bacteria, causing shrinkage of the bacterial membrane from the cell wall. Of special relevance, clinical isolates of P. acnes were vulnerable to chitosan, which could be combined with benzoyl peroxide for additive antibacterial effect. Chitosan also demonstrated significantly less cytotoxicity to monocytes than benzoyl peroxide. Overall, chitosan demonstrates many promising qualities for treatment of cutaneous pathogens. PMID:23829873

Champer, Jackson; Patel, Julie; Fernando, Nathalie; Salehi, Elaheh; Wong, Victoria; Kim, Jenny

2013-01-01

383

Quorum Sensing and Self-Quorum Quenching in the Intracellular Pathogen Brucellamelitensis  

PubMed Central

Brucella quorum sensing has been described as an important regulatory system controlling crucial virulence determinants such as the VirB type IV secretion system and the flagellar genes. However, the basis of quorum sensing, namely the production of autoinducers in Brucella has been questioned. Here, we report data obtained from the use of a genetic tool allowing the in situ detection of long-chain N-acyl-homoserine lactones (AHL) activity at single bacterium level in Brucella melitensis. These data are consistent with an intrinsic production of AHL by B. melitensis in low concentration both during in vitro growth and macrophage infection. Moreover, we identified a protein, named AibP, which is homologous to the AHL-acylases of various bacterial species. In vitro and during infection, expression of aibP coincided with a decrease in endogenous AHL activity within B. melitensis, suggesting that AibP could efficiently impair AHL accumulation. Furthermore, we showed that deletion of aibP in B. melitensis resulted in enhanced virB genes expression and VirB8 production as well as in a reduced flagellar genes expression and production of FlgE (hook protein) and FliC (flagellin) in vitro. Altogether, these results suggest that AHL-dependent quorum sensing and AHL-quorum quenching coexist in Brucella, at least to regulate its virulence. PMID:24349302

Terwagne, Matthieu; Mirabella, Aurelie; Lemaire, Julien; Deschamps, Chantal; De Bolle, Xavier; Letesson, Jean-Jacques

2013-01-01

384

NMR measurements of intracellular ions in hypertension  

NASA Astrophysics Data System (ADS)

The NMR methods for the measurement of intracellular free Na+, K+, Mg2+, Ca2+, and H+ are introduced. The recent literature is then presented showing applications of these methods to cells and tissues from hypertensive animal model systems, and humans with essential hypertension. The results support the hypothesis of consistent derangement of the intracellular ionic environment in hypertension. The theory that this derangement may be a common link in the disease states of high blood pressure and abnormal insulin and glucose metabolism, which are often associated clinically, is discussed.

Veniero, Joseph C.; Gupta, R. K.

1993-08-01

385

Intracellular Calcium Receptors: Calmodulin and Related Proteins  

NASA Technical Reports Server (NTRS)

Studies on intracellular calcium receptors, calmodulin and related proteins were carried out. Calcium binding proteins, like calmodulin fall into a class of proteins that are predominantly intracellular and reversibly bind calcium with dissociation constants in the micromolar to nanomolar range. Calcium regulation of these proteins appears to be due to localized increases in calcium concentrations in the cytoplasm. The main thrust of the research is concerned with purifying and characterizing the calcium receptors and trying to elucidate mechanistically how they are involved in cellular responses.

Watterson, D. M.

1983-01-01

386

Adhesion by Pathogenic Corynebacteria  

Microsoft Academic Search

\\u000a Pathogenic members of the genus Corynebacterium cause a wide range of serious infections in humans including diphtheria. Adhesion to host cells is a crucial step during\\u000a infection. In Corynebacterium diphtheriae, adhesion is mediated primarily by filamentous structures called pili or fimbriae that are covalently attached to the bacterial\\u000a cell wall. C. diphtheriae produces three distinct pilus structures, SpaA-, SpaD- and

Elizabeth A. Rogers; Asis Das; Hung Ton-That

387

Pathogenic agents in freshwater resources  

Microsoft Academic Search

Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and

Edwin E. Geldreich

1996-01-01

388

48 CFR 49.108-2 - Prime contractor's rights and obligations.  

Code of Federal Regulations, 2010 CFR

...108-2 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT TERMINATION OF CONTRACTS General Principles 49.108-2 Prime contractor's rights and obligations. (a) Termination...

2010-10-01

389

25 CFR 163.42 - Obligated service and breach of contract.  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER GENERAL FORESTRY REGULATIONS Forestry Education, Education Assistance, Recruitment...Obligated service. (1) Individuals completing forestry education programs with an...

2011-04-01

390

25 CFR 163.42 - Obligated service and breach of contract.  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER GENERAL FORESTRY REGULATIONS Forestry Education, Education Assistance, Recruitment...Obligated service. (1) Individuals completing forestry education programs with an...

2012-04-01

391

25 CFR 163.42 - Obligated service and breach of contract.  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF THE INTERIOR LAND AND WATER GENERAL FORESTRY REGULATIONS Forestry Education, Education Assistance, Recruitment...Obligated service. (1) Individuals completing forestry education programs with an...

2013-04-01

392

Federal Science And Engineering Obligations To Academic And Nonprofit Institutions Reached Record Highs In FY 2003  

NSF Publications Database

... Record Highs In FY 2003 by Richard Bennof Statistics from the National Science Foundation (NSF ... The National Science Foundation collects statistics on federal obligations to independent nonprofit ...

393

Pathogen Recognition and Inflammatory Signaling in Innate Immune Defenses  

PubMed Central

Summary: The innate immune system constitutes the first line of defense against invading microbial pathogens and relies on a large family of pattern recognition receptors (PRRs), which detect distinct evolutionarily conserved structures on pathogens, termed pathogen-associated molecular patterns (PAMPs). Among the PRRs, the Toll-like receptors have been studied most extensively. Upon PAMP engagement, PRRs trigger intracellular signaling cascades ultimately culminating in the expression of a variety of proinflammatory molecules, which together orchestrate the early host response to infection, and also is a prerequisite for the subsequent activation and shaping of adaptive immunity. In order to avoid immunopathology, this system is tightly regulated by a number of endogenous molecules that limit the magnitude and duration of the inflammatory response. Moreover, pathogenic microbes have developed sophisticated molecular strategies to subvert host defenses by interfering with molecules involved in inflammatory signaling. This review presents current knowledge on pathogen recognition through different families of PRRs and the increasingly complex signaling pathways responsible for activation of an inflammatory and antimicrobial response. Moreover, medical implications are discussed, including the role of PRRs in primary immunodeficiencies and in the pathogenesis of infectious and autoimmune diseases, as well as the possibilities for translation into clinical and therapeutic applications. PMID:19366914

Mogensen, Trine H.

2009-01-01

394

The Role of Cysteine Proteinases and their Inhibitors in the Host-Pathogen Cross Talk  

PubMed Central

Proteinases and their inhibitors play essential functional roles in basic biological processes in both hosts and pathogens. Endo/lysosomal cathepsins participate in immune response in pathogen recognition and elimination. They are essential for both antigen processing and presentation (host adaptive immune response) and activation of endosomal Toll like receptors (innate immune response). Pathogens can produce proteases and also natural inhibitors to subvert the host immune response. Several pathogens are sensed through the intracellular pathogen recognition receptors, but only some of them use the host proteolytic system to escape into the cytosol. In this review, I provide an update on the most recent developments regarding the role of proteinases and their inhibitors in the initiation and regulation of immune responses. PMID:23305363

Kopitar-Jerala, Natasa

2012-01-01

395

Noncanonical inflammasome activation of caspase-4/caspase-11 mediates epithelial defenses against enteric bacterial pathogens.  

PubMed

Inflammasome-mediated host defenses have been extensively studied in innate immune cells. Whether inflammasomes function for innate defense in intestinal epithelial cells, which represent the first line of defense against enteric pathogens, remains unknown. We observed enhanced Salmonella enterica serovar Typhimurium colonization in the intestinal epithelium of caspase-11-deficient mice, but not at systemic sites. In polarized epithelial monolayers, siRNA-mediated depletion of caspase-4, a human ortholog of caspase-11, also led to increased bacterial colonization. Decreased rates of pyroptotic cell death, a host defense mechanism that extrudes S. Typhimurium-infected cells from the polarized epithelium, accounted for increased pathogen burdens. The caspase-4 inflammasome also governs activation of the proinflammatory cytokine, interleukin (IL)-18, in response to intracellular (S. Typhimurium) and extracellular (enteropathogenic Escherichia coli) enteric pathogens, via intracellular LPS sensing. Therefore, an epithelial cell-intrinsic noncanonical inflammasome plays a critical role in antimicrobial defense at the intestinal mucosal surface. PMID:25121752

Knodler, Leigh A; Crowley, Shauna M; Sham, Ho Pan; Yang, Hyungjun; Wrande, Marie; Ma, Caixia; Ernst, Robert K; Steele-Mortimer, Olivia; Celli, Jean; Vallance, Bruce A

2014-08-13

396

Searching for Moniliophthora perniciosa pathogenicity genes.  

PubMed

The basidiomycete Moniliophthora perniciosa is the causal agent of witches' broom disease of Theobroma cacao (cacao). Pathogenesis mechanisms of this hemibiotrophic fungus are largely unknown. An approach to identify putative pathogenicity genes is searching for sequences induced in mycelia grown under in vitro conditions. Using this approach, genes from M. perniciosa induced under limiting nitrogen and light were identified from a cDNA library enriched by suppression subtractive hybridization as potential putative pathogenicity genes. From the 159 identified unique sequences, 59 were annotated and classified by gene ontology. Two sequences were categorized as "Defence genes, Virulence, and Cell response" presumably coding for allergenic proteins, whose homologues from other fungi are inducers of animal or plant defences. Differential gene expression was evaluated by quantitative amplification of reversed transcripts (RT-qPCR) of the putative identified genes coding for the two allergenic proteins (Aspf13 and 88KD), and for the enzymes Arylsulfatase (AS); Aryl-Alcohol Oxidase; Aldo-Keto Reductase (AK); Cytochrome P450 (P450); Phenylalanine Ammonia-Lyase; and Peroxidase from mycelia grown under contrasting N concentrations. All genes were validated for differential expression, except for the putative Peroxidase. The same eight genes were analysed for expression in susceptible plants inoculated with M. perniciosa, and six were induced during the early asymptomatic stage of the disease. In infected host tissues, transcripts of 88KD and AS were found more abundant at the biotrophic phase, while those from Aspf13, AK, PAL, and P450 accumulated at the necrotrophic phase, enabling to suggest that mycelia transition from biotrophic to necrotrophic might occur earlier than currently considered. These sequences appeared to be virulence life-style genes, which encode factors or enzymes that enable invasion, colonization or intracellular survival, or manipulate host factors to benefit the pathogen's own survival in the hostile environment. PMID:20943194

Leal, Gildemberg A; Gomes, Luiz H; Albuquerque, Paulo S B; Tavares, Flávio C A; Figueira, Antonio

2010-10-01

397

MicroRNA-155 Promotes Autophagy to Eliminate Intracellular Mycobacteria by Targeting Rheb  

PubMed Central

Mycobacterium tuberculosis is a hard-to-eradicate intracellular pathogen that infects one-third of the global population. It can live within macrophages owning to its ability to arrest phagolysosome biogenesis. Autophagy has recently been identified as an effective way to control the intracellular mycobacteria by enhancing phagosome maturation. In the present study, we demonstrate a novel role of miR-155 in regulating the autophagy-mediated anti-mycobacterial response. Both in vivo and in vitro studies showed that miR-155 expression was significantly enhanced after mycobacterial infection. Forced expression of miR-155 accelerated the autophagic response in macrophages, thus promoting the maturation of mycobacterial phagosomes and decreasing the survival rate of intracellular mycobacteria, while transfection with miR-155 inhibitor increased mycobacterial survival. However, macrophage-mediated mycobacterial phagocytosis was not affected after miR-155 overexpression or inhibition. Furthermore, blocking autophagy with specific inhibitor 3-methyladenine or silencing of autophagy related gene 7 (Atg7) reduced the ability of miR-155 to promote autophagy and mycobacterial elimination. More importantly, our study demonstrated that miR-155 bound to the 3?-untranslated region of Ras homologue enriched in brain (Rheb), a negative regulator of autophagy, accelerated the process of autophagy and sequential killing of intracellular mycobacteria by suppressing Rheb expression. Our results reveal a novel role of miR-155 in regulating autophagy-mediated mycobacterial elimination by targeting Rheb, and provide potential targets for clinical treatment. PMID:24130493

Zhou, Lin; MinhaoWu; Wu, Yongjian; Zhu, Min; Lai, XiaoMin; Chen, Tao; Feng, Lianqiang; Li, Meiyu; Huang, Chunyu; Zhong, Qiu; Huang, Xi

2013-01-01

398

The Brucella suis virB operon is induced intracellularly in macrophages  

PubMed Central

A type IV secretion system similar to the VirB system of the phytopathogen Agrobacterium tumefaciens is essential for the intracellular survival and multiplication of the mammalian pathogen Brucella. Reverse transcriptase–PCR showed that the 12 genes encoding the Brucella suis VirB system form an operon. Semiquantitative measurements of virB mRNA levels by slot blotting showed that transcription of the virB operon, but not the flanking genes, is regulated by environmental factors in vitro. Flow cytometry used to measure green fluorescent protein expression from the virB promoter confirmed the data from slot blots. Fluorescence-activated cell sorter analysis and fluorescence microscopy showed that the virB promoter is induced in macrophages within 3 h after infection. Induction only occurred once the bacteria were inside the cells, and phagosome acidification was shown to be the major signal inducing intracellular expression. Because phagosome acidification is essential for the intracellular multiplication of Brucella, we suggest that it is the signal that triggers the secretion of unknown effector molecules. These effector molecules play a role in the remodeling of the phagosome to create the unique intracellular compartment in which Brucella replicates. PMID:11830669

Boschiroli, Maria Laura; Ouahrani-Bettache, Safia; Foulongne, Vincent; Michaux-Charachon, Sylvie; Bourg, Gisele; Allardet-Servent, Annick; Cazevieille, Chantal; Liautard, Jean Pierre; Ramuz, Michel; O'Callaghan, David

2002-01-01

399

Duplications and losses in gene families of rust pathogens highlight putative effectors  

PubMed Central

Rust fungi are a group of fungal pathogens that cause some of the world's most destructive diseases of trees and crops. A shared characteristic among rust fungi is obligate biotrophy, the inability to complete a lifecycle without a host. This dependence on a host species likely affects patterns of gene expansion, contraction, and innovation within rust pathogen genomes. The establishment of disease by biotrophic pathogens is reliant upon effector proteins that are encoded in the fungal genome and secreted from the pathogen into the host's cell apoplast or within the cells. This study uses a comparative genomic approach to elucidate putative effectors and determine their evolutionary histories. We used OrthoMCL to identify nearly 20,000 gene families in proteomes of 16 diverse fungal species, which include 15 basidiomycetes and one ascomycete. We inferred patterns of duplication and loss for each gene family and identified families with distinctive patterns of expansion/contraction associated with the evolution of rust fungal genomes. To recognize potential contributors for the unique features of rust pathogens, we identified families harboring secreted proteins that: (i) arose or expanded in rust pathogens relative to other fungi, or (ii) contracted or were lost in rust fungal genomes. While the origin of rust fungi appears to be associated with considerable gene loss, there are many gene duplications associated with each sampled rust fungal genome. We also highlight two putative effector gene families that have expanded in Cqf that we hypothesize have roles in pathogenicity. PMID:25018762

Pendleton, Amanda L.; Smith, Katherine E.; Feau, Nicolas; Martin, Francis M.; Grigoriev, Igor V.; Hamelin, Richard; Nelson, C. Dana; Burleigh, J. Gordon; Davis, John M.

2014-01-01

400

Pulmonary Mycobacterium intracellulare disease with a solitary pulmonary nodule detected at the onset of pneumothorax.  

PubMed

A 61-year-old man with a past history of pulmonary emphysema 6 years earlier was admitted to the emergency department at our hospital because of cough and dyspnea. Left pneumothorax was recognized on a chest radiograph. After his admission to the emergency department, chest drainage was inserted and the left lung was expanded. Afterwards, a nodular shadow (>1.5 cm) was found in the left upper lobe, and differentiation from pulmonary adenocarcinoma was required. As a definite diagnosis could not be made by bronchoscopy, video-assisted thoracoscopic surgery was performed, and a solitary nodule in the left upper lobe was resected. Histologically, a caseating epitheloid granuloma with acid-fast bacilli was found. Regarding the causative pathogen, Mycobacterium intracellulare was identified from the surgically resected specimen. We have reported a peculiar case of pulmonary M. intracellulare disease, detected at the onset of left secondary pneumothorax caused by pulmonary emphysema, which required differentiation from pulmonary adenocarcinoma. PMID:16944259

Kobashi, Yoshihiro; Fukuda, Minoru; Yoshida, Kouichiro; Miyashita, Naoyuki; Oka, Mikio

2006-08-01

401

Intracellular regulation of neuronal nicotinic cholinoreceptors.  

PubMed

Experiments on isolated superior cervical ganglia from rats were used to study the effects of substances affecting intracellular second messengers on membrane currents evoked by iontophoretic application of acetylcholine (ACh currents) and on excitatory postsynaptic currents (EPSC) induced by single discharges of preganglionic nerve fibers. These studies showed that the adenylate cyclase activator forskolin, the phosphodiesterase inhibitor isobutylmethylxanthine (IMBX), and the protein kinase C activator phorbol ester decreased the amplitude of the ACh current. Neither IMBX nor phorbol ester had any effect on the amplitude or decay time constant of EPSC, while forskolin increased the amplitude of EPSC without altering its decay time constant. Thapsigargin, which liberates intracellular calcium, not only decreased the amplitude of the ACh current, but also decreased EPSC amplitude without affecting its decay time constant. These results suggest that intracellular signaling via protein kinases A and C may affect neuronal nicotinic cholinoceptors (nAChR) only by altering receptor desensitization and not affecting receptor sensitivity to transmitters released from nerves or the kinetics of receptor ion channels. At the same time, neuronal nAChR are influenced by intracellular calcium, which decreases their ability to be activated by exogenous (perhaps acting via desensitization) and nerve-released acetylcholine without affecting the kinetics of ion channel function. PMID:10768368

Voitenko, S V; Bobryshev, A Y; Skok, V I

2000-01-01

402

Evolution of signal transduction in intracellular symbiosis  

Microsoft Academic Search

Plant roots form intracellular symbioses with fungi and bacteria resulting in arbuscular mycorrhiza and nitrogen-fixing root nodules, respectively. A novel receptor like-kinase has been discovered that is required for the transduction of both bacterial and fungal symbiotic signals. This kinase defines an ancient signalling pathway that probably evolved in the context of arbuscular mycorrhiza and has been recruited subsequently for

Catherine Kistner; Martin Parniske

2002-01-01

403

Section III Intracellular Methods and Assays  

E-print Network

Abstract The twocomponent pathway in Escherichia coli chemotaxis has be- come a paradigm for bacterial intracellular kinase activity and thus to analyze properties of the chemotaxis signaling network. Introduction E. coli Chemotaxis Motile chemotactic bacteria are able to follow gradients of certain chemicals

Shimizu, Tom

404

Ehrlichia chaffeensis TRP32 Interacts with Host Cell Targets That Influence Intracellular Survival  

PubMed Central

Ehrlichia chaffeensis is an obligately intracellular bacterium that exhibits tropism for mononuclear phagocytes and survives by evading host cell defense mechanisms. Recently, molecular interactions of E. chaffeensis tandem repeat proteins 47 and 120 (TRP47 and -120) and the eukaryotic host cell have been described. In this investigation, yeast two-hybrid analysis demonstrated that an E. chaffeensis type 1 secretion system substrate, TRP32, interacts with a diverse group of human proteins associated with major biological processes of the host cell, including protein synthesis, trafficking, degradation, immune signaling, cell signaling, iron metabolism, and apoptosis. Eight target proteins, including translation elongation factor 1 alpha 1 (EF1A1), deleted in azoospermia (DAZ)-associated protein 2 (DAZAP2), ferritin light polypeptide (FTL), CD63, CD14, proteasome subunit beta type 1 (PSMB1), ring finger and CCCH-type domain 1 (RC3H1), and tumor protein p53-inducible protein 11 (TP53I11) interacted with TRP32 as determined by coimmunoprecipitation assays, colocalization with TRP32 in HeLa and THP-1 cells, and/or RNA interference. Interactions between TRP32 and host targets localized to the E. chaffeensis morulae or in the host cell cytoplasm adjacent to morulae. Common or closely related interacting partners of E. chaffeensis TRP32, TRP47, and TRP120 demonstrate a molecular convergence on common cellular processes and molecular cross talk between Ehrlichia TRPs and host targets. These findings further support the role of TRPs as effectors that promote intracellular survival. PMID:22547548

Luo, Tian

2012-01-01

405

Mutual obligation, shared responsibility agreements & indigenous health strategy  

PubMed Central

Since 2004 the Howard Coalition government has implemented a new policy framework and administrative arrangements as part of its program of reform in Indigenous affairs. In this paper I will describe both the parameters of this reform program and review the processes established to support the implementation of national Indigenous health strategy. In particular, I will consider both the shift from a policy framework based on 'self-determination' to one based on 'mutual obligation', and the implementation of Shared Responsibility Agreements (SRAs) that are based on the latter principle. I will use the example of the Mulan SRA to illustrate the difficulties in articulating the 'new arrangements' with current approaches to Indigenous health planning and strategy implementation. I conclude that 'new arrangements' pose a number of problems for Indigenous health planning and strategy that need to be addressed. PMID:16999873

Anderson, Ian PS

2006-01-01

406

Regulating Intracellular Antiviral Defense and Permissiveness to Hepatitis C Virus RNA Replication through a Cellular RNA Helicase, RIG-I  

Microsoft Academic Search

Virus-responsive signaling pathways that induce alpha\\/beta interferon production and engage intracellular immune defenses influence the outcome of many viral infections. The processes that trigger these defenses and their effect upon host permissiveness for specific viral pathogens are not well understood. We show that structured hepatitis C virus (HCV) genomic RNA activates interferon regulatory factor 3 (IRF3), thereby inducing interferon in

Rhea Sumpter; Y.-M. Loo; E. Foy; K. Li; M. Yoneyama; T. Fujita; S. M. Lemon; M. Gale

2005-01-01

407

BRIEF COMMUNICATION The Role of Intracellular Receptor NODs for Cytokine Production by Macrophages Infected with Mycobacterium leprae  

E-print Network

The nucleotide-oligomerization domain (NOD) proteins are members of the NOD-like receptor (NLR) family, which are intracellular and cytoplasmic receptors. We analyzed the role of NODs for cytokine production by macrophages infected with intracellular pathogen M. leprae, the causative agent of leprosy. Production of pro-inflammatory cytokines such as IL-1? and TNF-? was inhibited in the presence of cytochalasin D, an agent blocking phagocytosis, suggesting that intracellular signaling was, partially, required for macrophage activation to M. leprae infection. Next, we investigated the role of NOD1 and NOD2 proteins on NF-?B activation and cytokine expression. Treatment with M. leprae significantly increased NF-?B activation and expression of TNF-? and IL-1? in NOD1- and NOD2-transfected cells. Interestingly, their activation and expression were inhibited by cytochalasin

Tae Jin Kang; Gue-tae Chae

408

BK polyomavirus: emerging pathogen  

PubMed Central

BK polyomavirus (BKPyV) is a small double-stranded DNA virus that is an emerging pathogen in immunocompromised individuals. BKPyV is widespread in the general population, but primarily causes disease when immune suppression leads to reactivation of latent virus. Polyomavirus-associated nephropathy and hemorrhagic cystitis in renal and bone marrow transplant patients, respectively, are the most common diseases associated with BKPyV reactivation and lytic infection. In this review, we discuss the clinical relevance, effects on the host, virus life cycle, and current treatment protocols. PMID:22402031

Bennett, Shauna M.; Broekema, Nicole M.; Imperiale, Michael J.

2013-01-01

409

Host-Pathogen Interactions  

PubMed Central

A polysaccharide from the fungal pathogen Colletotrichum lindemuthianum causes browning and phytoalexin production when applied to the cut surfaces of bean (Phaseolus vulgaris) cotyledons and hypocotyls. The application of an amount of polysaccharide equivalent to less than 100 ng of glucose will elicit this response in the bean tissues. The polysaccharide has been isolated both from culture filtrates and from the mycelial walls of the fungus. Purification of the polysaccharide involved anion and cation exchange chromatography and gel filtration. The polysaccharide has an apparent molecular weight between 1,000,000 and 5,000,000 daltons, and consists predominantly of 3- and 4-linked glucosyl residues. PMID:16659289

Anderson-Prouty, Anne J.; Albersheim, Peter

1975-01-01

410

Host-pathogen interactions and immune evasion strategies in Francisella tularensis pathogenicity  

PubMed Central

Francisella tularensis is an intracellular Gram-negative bacterium that causes life-threatening tularemia. Although the prevalence of natural infection is low, F. tularensis remains a tier I priority pathogen due to its extreme virulence and ease of aerosol dissemination. F. tularensis can infect a host through multiple routes, including the intradermal and respiratory routes. Respiratory infection can result from a very small inoculum (ten organisms or fewer) and is the most lethal form of infection. Following infection, F. tularensis employs strategies for immune evasion that delay the immune response, permitting systemic distribution and induction of sepsis. In this review we summarize the current knowledge of F. tularensis in an immunological context, with emphasis on the host response and bacterial evasion of that response. PMID:25258544

Steiner, Don J; Furuya, Yoichi; Metzger, Dennis W

2014-01-01

411

The Role of Family Obligations and School Adjustment in Explaining the Immigrant Paradox  

ERIC Educational Resources Information Center

This study examined the role of family obligations and school adjustment in explaining immigrant adolescents' adaptation. Despite a relatively low socio-economic status, immigrant adolescents have been found to have a pattern of adaptation superior to that of national adolescents. Immigrant adolescents' strong sense of family obligations and…

van Geel, Mitch; Vedder, Paul

2011-01-01

412

The Lived Experience of How Adult Nursing Students Blend Lifestyle Obligations with Nursing School Expectations  

ERIC Educational Resources Information Center

Many adult nursing students have lifestyle obligations that require integration with nursing school programs in order to graduate and fulfill their dreams of becoming a nurse. Fourteen participants shared their stories of how they were able to blend their lifestyles commitments with nursing school. Student interaction between lifestyle obligations

Coutrier, Karen A.

2011-01-01

413

Cognitive Representations of Obligation and Prohibition Signs when They Provide the Same Amount of Semantic Information  

ERIC Educational Resources Information Center

The aim of this research was to test whether there is an inherent difficulty in understanding prohibition signs rather than obligation signs. In the experiment conducted, participants decided whether simple car movements presented on a computer screen were allowed or not according to either obligation or prohibition traffic signs. The information…

Castro, C.; Moreno-Rios, S.; Tornay, F. J.

2012-01-01

414

Conceptualising Hy-Bivalent Subjectivities to Facilitate an Examination of Australian Government Mutual Obligations Policies  

ERIC Educational Resources Information Center

This paper illustrates how the work of feminist theorists Valerie Walkerdine, Helen Lucey and June Melody, Beverly Skeggs, and Nancy Fraser were used together to examine the lived effects of Australian government Mutual Obligations policies. As "active" welfare policies, Mutual Obligations construct particular relations between themselves and…

Edwards, Jan

2006-01-01

415

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

...cellulosic biofuel, in gallons. (2) Biomass-based diesel. RVOBBD,i = (RFStdBBD... = The Renewable Volume Obligation for biomass-based diesel for an obligated party... RFStdBBD,i = The standard for biomass-based diesel for calendar year i,...

2014-07-01

416

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

Code of Federal Regulations, 2010 CFR

...cellulosic biofuel, in gallons. (2) Biomass-based diesel. RVOBBD,i = (RFStdBBD... = The Renewable Volume Obligation for biomass-based diesel for an obligated party... RFStdBBD,i = The standard for biomass-based diesel for calendar year i,...

2010-07-01

417

34 CFR 370.47 - When must grant funds be obligated?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false When must grant funds be obligated? 370.47 Section 370.47...PROGRAM What Post-Award Conditions Must Be Met by a Designated Agency? § 370.47 When must grant funds be obligated? (a) Any funds...

2010-07-01

418

17 CFR 240.17Ad-17 - Transfer agents' obligation to search for lost securityholders.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Transfer agents' obligation to search for lost securityholders...Company Rules § 240.17Ad-17 Transfer agents' obligation to search for lost securityholders...a)(1) Every recordkeeping transfer agent whose master securityholder...

2011-04-01

419

Abalone farm discharges the withering syndrome pathogen into the wild  

PubMed Central

An intracellular bacterium Candidatus Xenohaliotis californiensis, also called Withering-Syndrome Rickettsia-Like Organism (WS-RLO), is the cause of mass mortalities that are the chief reason for endangerment of black abalone (Haliotis cracherodii). Using a real-time PCR assay, we found that a shore-based abalone farm (AF) in Santa Barbara, CA, USA discharged WS-RLO DNA into the ocean. Several other shore-based AFs discharge effluent into critical habitat for black abalone in California and this might affect the recovery of wild black abalone. Existing regulatory frameworks exist that could help protect wild species from pathogens released from shore-based aquaculture. PMID:24367359

Lafferty, Kevin D.; Ben-Horin, Tal

2013-01-01

420

Abalone farm discharges the withering syndrome pathogen into the wild  

USGS Publications Warehouse

An intracellular bacterium Candidatus Xenohaliotis californiensis, also called Withering-Syndrome Rickettsia-Like Organism (WS-RLO), is the cause of mass mortalities that are the chief reason for endangerment of black abalone (Haliotis cracherodii). Using a real-time PCR assay, we found that a shore-based abalone farm (AF) in Santa Barbara, CA, USA discharged WS-RLO DNA into the ocean. Several other shore-based AFs discharge effluent into critical habitat for black abalone in California and this might affect the recovery of wild black abalone. Existing regulatory frameworks exist that could help protect wild species from pathogens released from shore-based aquaculture.

Lafferty, Kevin D.; Ben-Horin, Tal

2014-01-01

421

A method for detecting intracellular perforin in mouse lymphocytes.  

PubMed

Cytotoxic lymphocytes destroy pathogen-infected and transformed cells through the cytotoxic granule exocytosis death pathway, which is dependent on the delivery of proapoptotic granzymes into the target cell cytosol by the pore-forming protein, perforin. Despite the importance of mouse models in understanding the role of cytotoxic lymphocytes in immune-mediated disease and their role in cancer immune surveillance, no reliable intracellular detection method exists for mouse perforin. Consequently, rapid, flow-based assessment of cytotoxic potential has been problematic, and complex assays of function are generally required. In this study, we have developed a novel method for detecting perforin in primary mouse cytotoxic T lymphocytes by immunofluorescence and flow cytometry. We used this new technique to validate perforin colocalization with granzyme B in cytotoxic granules polarized to the immunological synapse, and to assess the expression of perforin in cytotoxic T lymphocytes at various stages of activation. The sensitivity of this technique also allowed us to distinguish perforin levels in Prf1(+/+) and Prf1(+/-) mice. This new methodology will have broad applications and contribute to advances within the fields of lymphocyte biology, infectious disease, and cancer. PMID:25348626

Brennan, Amelia J; House, Imran G; Oliaro, Jane; Ramsbottom, Kelly M; Hagn, Magdalena; Yagita, Hideo; Trapani, Joseph A; Voskoboinik, Ilia

2014-12-01

422

Shiga Toxins: Intracellular Trafficking to the ER Leading to Activation of Host Cell Stress Responses  

PubMed Central

Despite efforts to improve hygenic conditions and regulate food and drinking water safety, the enteric pathogens, Shiga toxin-producing Escherichia coli (STEC) and Shigella dysenteriae serotype 1 remain major public health concerns due to widespread outbreaks and the severity of extra-intestinal diseases they cause, including acute renal failure and central nervous system complications. Shiga toxins are the key virulence factors expressed by these pathogens mediating extra-intestinal disease. Delivery of the toxins to the endoplasmic reticulum (ER) results in host cell protein synthesis inhibition, activation of the ribotoxic stress response, the ER stress response, and in some cases, the induction of apoptosis. Intrinsic and/or extrinsic apoptosis inducing pathways are involved in executing cell death following intoxication. In this review we provide an overview of the current understanding Shiga toxin intracellular trafficking, host cellular responses to the toxin and ER stress-induced apoptosis with an emphasis on recent findings. PMID:22069648

Lee, Moo-Seung; Cherla, Rama P.; Tesh, Vernon L.

2010-01-01

423

Cryptosporidium Pathogenicity and Virulence  

PubMed Central

Cryptosporidium is a protozoan parasite of medical and veterinary importance that causes gastroenteritis in a variety of vertebrate hosts. Several studies have reported different degrees of pathogenicity and virulence among Cryptosporidium species and isolates of the same species as well as evidence of variation in host susceptibility to infection. The identification and validation of Cryptosporidium virulence factors have been hindered by the renowned difficulties pertaining to the in vitro culture and genetic manipulation of this parasite. Nevertheless, substantial progress has been made in identifying putative virulence factors for Cryptosporidium. This progress has been accelerated since the publication of the Cryptosporidium parvum and C. hominis genomes, with the characterization of over 25 putative virulence factors identified by using a variety of immunological and molecular techniques and which are proposed to be involved in aspects of host-pathogen interactions from adhesion and locomotion to invasion and proliferation. Progress has also been made in the contribution of host factors that are associated with variations in both the severity and risk of infection. Here we provide a review comprised of the current state of knowledge on Cryptosporidium infectivity, pathogenesis, and transmissibility in light of our contemporary understanding of microbial virulence. PMID:23297262

Bouzid, Maha; Chalmers, Rachel M.; Tyler, Kevin M.

2013-01-01

424

Host-Pathogen Interactions  

PubMed Central

An elicitor of glyceollin accumulation in soybeans (Glycine max L.) has been isolated from a commercially available extract of brewers' yeast. Yeast is not a known pathogen of plants. The elicitor was isolated by precipitation in 80% (v/v) ethanol followed by column chromatography on DEAE-cellulose, sulfopropyl-Sephadex, and concanavalin A-Sepharose. Compositional and structural analysis showed the elicitor to be a glucan containing terminal, 3-, 6-, and 3,6-linked glucosyl residues. The yeast elicitor stimulates the accumulation of glyceollin in the cotyledons and hypocotyls of soybeans when as little as 15 nanograms or 100 nanograms of the elicitor is applied to the respective tissues. The yeast elicitor is very similar in both structure and absolute elicitor activity to an elicitor isolated from the mycelial walls of Phytophthora megasperma var. sojae, a pathogen of soybeans. These and other results of this laboratory suggest that plants are able to respond to the presence of a wide range of fungi by recognizing, as foreign to the plant, structural polysaccharides of the mycelial walls of the fungi. PMID:16660446

Hahn, Michael G.; Albersheim, Peter

1978-01-01

425

Copper Homeostasis at the Host-Pathogen Interface*  

PubMed Central

The trace element copper is indispensable for all aerobic life forms. Its ability to cycle between two oxidation states, Cu1+ and Cu2+, has been harnessed by a wide array of metalloenzymes that catalyze electron transfer reactions. The metabolic needs for copper are sustained by a complex series of transporters and carrier proteins that regulate its intracellular accumulation and distribution in both pathogenic microbes and their animal hosts. However, copper is also potentially toxic due in part to its ability to generate reactive oxygen species. Recent studies suggest that the macrophage phagosome accumulates copper during bacterial infection, which may constitute an important mechanism of killing. Bacterial countermeasures include the up-regulation of copper export and detoxification genes during infection, which studies suggest are important determinants of virulence. In this minireview, we summarize recent developments that suggest an emerging role for copper as an unexpected component in determining the outcome of host-pathogen interactions. PMID:22389498

Hodgkinson, Victoria; Petris, Michael J.

2012-01-01

426

Felt obligation and the family life cycle: a study on intergenerational relationships.  

PubMed

Since the 1990s researchers have considered as the dominant view on family obligation a set of responsibilities, duties, and obligation of care and assistance,that adult children should assume when parents are old or infirm. This concept is limited, because it assumes that family obligation is salient only in one period of life: when parents reach old age and are infirm. In contrast, a relational approach to family obligation considers family relationships as central to understanding children's duties and responsibilities. Following Stein, family obligation can be defined as felt obligation: expectations for appropriate and negotiated behaviour, perceived within the context of specific personal relationships with kin across life course. Felt obligation is conceptualized in five dimensions: a duty to maintain contact, assistance, avoidance of conflict, personal sharing, and self-sufficiency. The purpose of the present study was to analyze perceptions of felt obligation in intergenerational relationships (parent-child and family of origin) in different phases of the family life cycle in a specific cultural context (Italy). The sample was composed of 92 parents with children of different ages (infants, school-aged children, and young adults).The measure addressed the five dimensions of felt obligation, all assessed in various phases of family life. Results indicated differences in dimensions of felt obligation between intergenerational relationships (both parent-child and with family of origin). Some of these differences, such as self-sufficiency and personal sharing, assumed more importance and salience in some periods of the life cycle than in others. PMID:23016537

Del Corso, Annalisa Rossi; Lanz, Margherita

2013-01-01

427

The Complete Genome of Teredinibacter turnerae T7901: An Intracellular Endosymbiont of Marine Wood-Boring Bivalves (Shipworms)  

PubMed Central

Here we report the complete genome sequence of Teredinibacter turnerae T7901. T. turnerae is a marine gamma proteobacterium that occurs as an intracellular endosymbiont in the gills of wood-boring marine bivalves of the family Teredinidae (shipworms). This species is the sole cultivated member of an endosymbiotic consortium thought to provide the host with enzymes, including cellulases and nitrogenase, critical for digestion of wood and supplementation of the host's nitrogen-deficient diet. T. turnerae is closely related to the free-living marine polysaccharide degrading bacterium Saccharophagus degradans str. 2–40 and to as yet uncultivated endosymbionts with which it coexists in shipworm cells. Like S. degradans, the T. turnerae genome encodes a large number of enzymes predicted to be involved in complex polysaccharide degradation (>100). However, unlike S. degradans, which degrades a broad spectrum (>10 classes) of complex plant, fungal and algal polysaccharides, T. turnerae primarily encodes enzymes associated with deconstruction of terrestrial woody plant material. Also unlike S. degradans and many other eubacteria, T. turnerae dedicates a large proportion of its genome to genes predicted to function in secondary metabolism. Despite its intracellular niche, the T. turnerae genome lacks many features associated with obligate intracellular existence (e.g. reduced genome size, reduced %G+C, loss of genes of core metabolism) and displays evidence of adaptations common to free-living bacteria (e.g. defense against bacteriophage infection). These results suggest that T. turnerae is likely a facultative intracellular ensosymbiont whose niche presently includes, or recently included, free-living existence. As such, the T. turnerae genome provides insights into the range of genomic adaptations associated with intracellular endosymbiosis as well as enzymatic mechanisms relevant to the recycling of plant materials in marine environments and the production of cellulose-derived biofuels. PMID:19568419

Yang, Joyce C.; Madupu, Ramana; Durkin, A. Scott; Ekborg, Nathan A.; Pedamallu, Chandra S.; Hostetler, Jessica B.; Radune, Diana; Toms, Bradley S.; Henrissat, Bernard; Coutinho, Pedro M.; Schwarz, Sandra; Field, Lauren; Trindade-Silva, Amaro E.; Soares, Carlos A. G.; Elshahawi, Sherif; Hanora, Amro; Schmidt, Eric W.; Haygood, Margo G.; Posfai, Janos; Benner, Jack; Madinger, Catherine; Nove, John; Anton, Brian; Chaudhary, Kshitiz; Foster, Jeremy; Holman, Alex; Kumar, Sanjay; Lessard, Philip A.; Luyten, Yvette A.; Slatko, Barton; Wood, Nicole; Wu, Bo; Teplitski, Max; Mougous, Joseph D.; Ward, Naomi; Eisen, Jonathan A.; Badger, Jonathan H.; Distel, Daniel L.

2009-01-01

428

The complete genome of Teredinibacter turnerae T7901: an intracellular endosymbiont of marine wood-boring bivalves (shipworms).  

PubMed

Here we report the complete genome sequence of Teredinibacter turnerae T7901. T. turnerae is a marine gamma proteobacterium that occurs as an intracellular endosymbiont in the gills of wood-boring marine bivalves of the family Teredinidae (shipworms). This species is the sole cultivated member of an endosymbiotic consortium thought to provide the host with enzymes, including cellulases and nitrogenase, critical for digestion of wood and supplementation of the host's nitrogen-deficient diet. T. turnerae is closely related to the free-living marine polysaccharide degrading bacterium Saccharophagus degradans str. 2-40 and to as yet uncultivated endosymbionts with which it coexists in shipworm cells. Like S. degradans, the T. turnerae genome encodes a large number of enzymes predicted to be involved in complex polysaccharide degradation (>100). However, unlike S. degradans, which degrades a broad spectrum (>10 classes) of complex plant, fungal and algal polysaccharides, T. turnerae primarily encodes enzymes associated with deconstruction of terrestrial woody plant material. Also unlike S. degradans and many other eubacteria, T. turnerae dedicates a large proportion of its genome to genes predicted to function in secondary metabolism. Despite its intracellular niche, the T. turnerae genome lacks many features associated with obligate intracellular existence (e.g. reduced genome size, reduced %G+C, loss of genes of core metabolism) and displays evidence of adaptations common to free-living bacteria (e.g. defense against bacteriophage infection). These results suggest that T. turnerae is likely a facultative intracellular ensosymbiont whose niche presently includes, or recently included, free-living existence. As such, the T. turnerae genome provides insights into the range of genomic adaptations associated with intracellular endosymbiosis as well as enzymatic mechanisms relevant to the recycling of plant materials in marine environments and the production of cellulose-derived biofuels. PMID:19568419

Yang, Joyce C; Madupu, Ramana; Durkin, A Scott; Ekborg, Nathan A; Pedamallu, Chandra S; Hostetler, Jessica B; Radune, Diana; Toms, Bradley S; Henrissat, Bernard; Coutinho, Pedro M; Schwarz, Sandra; Field, Lauren; Trindade-Silva, Amaro E; Soares, Carlos A G; Elshahawi, Sherif; Hanora, Amro; Schmidt, Eric W; Haygood, Margo G; Posfai, Janos; Benner, Jack; Madinger, Catherine; Nove, John; Anton, Brian; Chaudhary, Kshitiz; Foster, Jeremy; Holman, Alex; Kumar, Sanjay; Lessard, Philip A; Luyten, Yvette A; Slatko, Barton; Wood, Nicole; Wu, Bo; Teplitski, Max; Mougous, Joseph D; Ward, Naomi; Eisen, Jonathan A; Badger, Jonathan H; Distel, Daniel L

2009-01-01

429

A host-restricted viral vector for antigen-specific immunization against Lyme disease pathogen.  

PubMed

Newcastle disease virus (NDV) is an avian virus that is attenuated in primates and is a potential vaccine vector for human use. We evaluated NDV as a vector for expressing selected antigens of the Lyme disease pathogen Borrelia burgdorferi. A series of recombinant NDVs were generated that expressed intracellular or extracellular forms of two B. burgdorferi antigens: namely, the basic membrane protein A (BmpA) and the outer surface protein C (OspC). Expression of the intracellular and extracellular forms of these antigens was confirmed in cultured chicken cells. C3H or Balb/C mice that were immunized intranasally with the NDV vectors mounted vigorous serum antibody responses against the NDV vector, but failed to mount a robust response against either the intracellular or extracellular forms of BmpA or OspC. By contrast, a single immunization of hamsters with the NDV vectors via the intranasal, intramuscular, or intraperitoneal route resulted in rapid and rigorous antibody responses against the intracellular or extracellular forms of BmpA and OspC. When groups of hamsters were separately inoculated with various NDV vectors and challenged with B. burgdorferi (10(8)cells/animal), immunization with vector expressing either intracellular or extracellular BmpA was associated with a significant reduction of the pathogen load in the joints. Taken together, our studies highlighted the importance of NDV as vaccine vector that can be used for simple yet effective immunization of hosts against bacterial infections including Lyme disease. PMID:21600949

Xiao, Sa; Kumar, Manish; Yang, Xiuli; Akkoyunlu, Mustafa; Collins, Peter L; Samal, Siba K; Pal, Utpal

2011-07-18

430

A host-restricted viral vector for antigen-specific immunization against Lyme disease pathogen  

PubMed Central

Newcastle disease virus (NDV) is an avian virus that is attenuated in primates and is a potential vaccine vector for human use. We evaluated NDV as a vector for expressing selected antigens of the Lyme disease pathogen Borrelia burgdorferi. A series of recombinant NDVs were generated that expressed intracellular or extracellular forms of two Borrelia burgdorferi antigens: namely, the basic membrane protein A (BmpA) and the outer surface protein C (OspC). Expression of the intracellular and extracellular forms of these antigens was confirmed in cultured chicken cells. C3H or Balb/C mice that were immunized intranasally with the NDV vectors mounted vigorous serum antibody responses against the NDV vector, but failed to mount a robust response against either the intracellular or extracellular forms of BmpA or OspC. In contrast, a single immunization of hamsters with the NDV vectors via the intranasal, intramuscular, or intraperitoneal route resulted in rapid and rigorous antibody responses against the intracellular or extracellular forms of BmpA and OspC. When groups of hamsters were separately inoculated with various NDV vectors and challenged with B. burgdorferi (108 cells/animal), immunization with vector expressing either intracellular or extracellular BmpA was associated with a significant reduction of the pathogen load in the joints. Taken together, our studies highlighted the importance of NDV as vaccine vector that can be used for simple yet effective immunization of hosts against bacterial infections including Lyme disease. PMID:21600949

Xiao, Sa; Kumar, Manish; Yang, Xiuli; Akkoyunlu, Mustafa; Collins, Peter L.; Samal, Siba K.; Pal, Utpal

2011-01-01

431

Adaptor protein complexes and intracellular transport  

PubMed Central

The AP (adaptor protein) complexes are heterotetrameric protein complexes that mediate intracellular membrane trafficking along endocytic and secretory transport pathways. There are five different AP complexes: AP-1, AP-2 and AP-3 are clathrin-associated complexes; whereas AP-4 and AP-5 are not. These five AP complexes localize to different intracellular compartments and mediate membrane trafficking in distinct pathways. They recognize and concentrate cargo proteins into vesicular carriers that mediate transport from a donor membrane to a target organellar membrane. AP complexes play important roles in maintaining the normal physiological function of eukaryotic cells. Dysfunction of AP complexes has been implicated in a variety of inherited disorders, including: MEDNIK (mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis and keratodermia) syndrome, Fried syndrome, HPS (Hermansky–Pudlak syndrome) and HSP (hereditary spastic paraplegia). PMID:24975939

Park, Sang Yoon; Guo, Xiaoli

2014-01-01

432

Adaptor protein complexes and intracellular transport.  

PubMed

The AP (adaptor protein) complexes are heterotetrameric protein complexes that mediate intracellular membrane trafficking along endocytic and secretory transport pathways. There are five different AP complexes: AP-1, AP-2 and AP-3 are clathrin-associated complexes; whereas AP-4 and AP-5 are not. These five AP complexes localize to different intracellular compartments and mediate membrane trafficking in distinct pathways. They recognize and concentrate cargo proteins into vesicular carriers that mediate transport from a donor membrane to a target organellar membrane. AP complexes play important roles in maintaining the normal physiological function of eukaryotic cells. Dysfunction of AP complexes has been implicated in a variety of inherited disorders, including: MEDNIK (mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis and keratodermia) syndrome, Fried syndrome, HPS (Hermansky-Pudlak syndrome) and HSP (hereditary spastic paraplegia). PMID:24975939

Park, Sang Yoon; Guo, Xiaoli

2014-01-01

433

Intracellular regulation of neuronal nicotinic cholinorceptors  

Microsoft Academic Search

Experiments on isolated superior cervical ganglia from rats were used to study the effects of substances affecting intracellular\\u000a second messengers on membrane currents evoked by iontophoretic application of acetylcholine (ACh currents) and on excitatory\\u000a postsynaptic currents (EPSC) induced by single discharges of preganglionic nerve fibers. These studies showed that the adenylate\\u000a cyclase activator forskolin, the phosphodiesterase inhibitor isobutylmethylxanthine (IMBX), and

S. V. Voitenko; A. Yu. Bobryshev; V. I. Skok

2000-01-01

434

Intracellular Calcium Handling and Inherited Arrhythmogenic Diseases  

Microsoft Academic Search

\\u000a Inherited arrhythmogenic diseases occur in the absence of morphological abnormalities of the heart, and common symptoms are\\u000a syncope and sudden death due to ventricular tachycardia\\/fibrillation. In this chapter, we discuss genetic abnormalities that\\u000a lead to altered intracellular calcium handling and susceptibility to ventricular tachyarrhythmias. The three diseases that\\u000a we will discuss are as follows: (1) catecholaminergic polymorphic ventricular tachycardia (CPVT)

Nicola Monteforte; Carlo Napolitano; Raffaella Bloise; Silvia G. Priori

435

Toward Intracellular Targeted Delivery of Cancer Therapeutics  

PubMed Central

A number of anti-cancer drugs have their targets localized to particular intracellular compartments. These drugs reach the targets mainly through diffusion, dependent on biophysical and biochemical forces that allow cell penetration. This means that both cancer cells and normal cells will be subjected to such diffusion; hence many of these drugs, like chemotherapeutics, are potentially toxic and the concentration achieved at the site of their action is often suboptimal. The same relates to radiation that indiscriminately affects normal and diseased cells. However, nature-designed systems enable compounds present in the extracellular environment to end up inside the cell and even travel to more specific intracellular compartments. For example, viruses and bacterial toxins can more or less specifically recognize eukaryotic cells, enter these cells, and direct some protein portions to designated intracellular areas. These phenomena have led to creative thinking, such as employing viruses or bacterial toxins for cargo delivery to cells and, more specifically, to cancer cells. Proteins can be genetically engineered in order to not only mimic what viruses and bacterial toxins can do, but also to add new functions, extending or changing the intracellular routes. It is possible to make conjugates or, more preferably, single-chain proteins that recognize cancer cells and deliver cargo inside the cells, even to the desired subcellular compartment. These findings offer new opportunities to deliver drugs/labels only to cancer cells and only to their site of action within the cells. The development of such dual-specificity vectors for targeting cancer cells is an attractive and potentially safer and more efficacious way of delivering drugs. We provide examples of this approach for delivering brain cancer therapeutics, using a specific biomarker on glioblastoma tumor cells. PMID:22671766

Pandya, Hetal; Debinski, Waldemar

2013-01-01

436

24 CFR 350.4 - Law governing rights and obligations of United States, and Federal Reserve Banks as Depositories...  

Code of Federal Regulations, 2010 CFR

...obligations of United States, and Federal Reserve Banks as Depositories; Rights...Person against United States, and Federal Reserve Banks as Depositories; Law Governing...obligations of United States, and Federal Reserve Banks as Depositories;...

2010-04-01

437

24 CFR 81.92 - Law governing rights and obligations of United States, Federal Reserve Banks, and GSEs; rights of...  

Code of Federal Regulations, 2010 CFR

...obligations of United States, Federal Reserve Banks, and GSEs; rights of any Person against United States, Federal Reserve Banks, and GSEs; Law governing...obligations of United States, Federal Reserve Banks, and GSEs; rights...

2010-04-01

438

12 CFR 1.130 - Type II securities; guidelines for obligations issued for university and housing purposes.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Type II securities; guidelines for obligations issued for university...Interpretations § 1.130 Type II securities; guidelines for obligations issued for university...the hospital staff, and training of medical students, interns, residents,...

2011-01-01

439

45 CFR 309.135 - What requirements apply to funding, obligating and liquidating Federal title IV-D grant funds?  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false What requirements apply to funding, obligating and liquidating Federal title...IV-D) PROGRAM Tribal IV-D Program Funding § 309.135 What requirements apply to funding, obligating and liquidating Federal...

2012-10-01

440

45 CFR 309.135 - What requirements apply to funding, obligating and liquidating Federal title IV-D grant funds?  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false What requirements apply to funding, obligating and liquidating Federal title...IV-D) PROGRAM Tribal IV-D Program Funding § 309.135 What requirements apply to funding, obligating and liquidating Federal...

2011-10-01

441

45 CFR 309.135 - What requirements apply to funding, obligating and liquidating Federal title IV-D grant funds?  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false What requirements apply to funding, obligating and liquidating Federal title...IV-D) PROGRAM Tribal IV-D Program Funding § 309.135 What requirements apply to funding, obligating and liquidating Federal...

2010-10-01

442

45 CFR 309.135 - What requirements apply to funding, obligating and liquidating Federal title IV-D grant funds?  

Code of Federal Regulations, 2013 CFR

...2012-10-01 true What requirements apply to funding, obligating and liquidating Federal title...IV-D) PROGRAM Tribal IV-D Program Funding § 309.135 What requirements apply to funding, obligating and liquidating Federal...

2013-10-01

443

42 CFR 411.22 - Reimbursement obligations of primary payers and entities that received payment from primary payers.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Reimbursement obligations of primary payers and entities that received payment from primary payers. 411.22 Section 411.22...411.22 Reimbursement obligations of primary payers and entities that received...

2010-10-01

444

45 CFR 309.135 - What requirements apply to funding, obligating and liquidating Federal title IV-D grant funds?  

...2012-10-01 true What requirements apply to funding, obligating and liquidating Federal title...IV-D) PROGRAM Tribal IV-D Program Funding § 309.135 What requirements apply to funding, obligating and liquidating Federal...

2014-10-01

445

26 CFR 46.4701-1 - Tax on issuer of registration-required obligation not in registered form.  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES EXCISE TAX ON POLICIES ISSUED BY FOREIGN INSURERS AND OBLIGATIONS NOT IN REGISTERED FORM Excise Tax on Obligations Not in Registered Form §...

2011-04-01

446

26 CFR 46.4701-1 - Tax on issuer of registration-required obligation not in registered form.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES EXCISE TAX ON POLICIES ISSUED BY FOREIGN INSURERS AND OBLIGATIONS NOT IN REGISTERED FORM Excise Tax on Obligations Not in Registered Form §...

2010-04-01

447

42 CFR 137.251. - What obligation does the retroceding Self-Governance Tribe have with respect to returning...  

Code of Federal Regulations, 2010 CFR

...obligation does the retroceding Self-Governance Tribe have with respect to...HUMAN SERVICES TRIBAL SELF-GOVERNANCE Retrocession § 137.251...obligation does the retroceding Self-Governance Tribe have with respect...

2010-10-01

448

[Intracellular regulation of neuronal nicotinic cholinergic receptors].  

PubMed

Effects of substances affecting intracellular secondary messengers on the membrane currents evoked by ionophoretic application of acetylcholine (ACh currents) and on the excitatory postsynaptic currents (EPSC) evoked by single stimuli applied to preganglionic nerve fibres, were studied in neurones of the rat isolated superior cervical ganglion. Forskolin, the protein kinase A activator, and isobutyl-methyxanthine, the phosphodiesterase inhibitor, decreased the ACh currents. Neither forskolin nor isobutyl-methylxanthine affected the EPSC amplitude or the EPSC decay time constant. Phorbol ester, the protein kinase C activator, decreased the ACh current but did not affect either EPSC amplitude or the EPSC decay time constant. Thapsigargin, the intracellular calcium releaser, decreased the ACh current and the EPSC amplitude but did not affect the EPSC decay time constant. The data obtained suggest that nicotinic acetylcholine receptors (nAChRs) of ganglion neurones are not modulated through the pathways involving protein kinase A or protein kinase C. The nAChRs sensitivity to both exogenous and nerve-released acetylcholine is reduced by intracellular calcium without affecting kinetics of their ionic channels. PMID:10097266

Vo?tenko, S V; Bobryshev, A Iu; Skok, V I

1998-10-01

449

Error Propagation Analysis for Quantitative Intracellular Metabolomics  

PubMed Central

Model-based analyses have become an integral part of modern metabolic engineering and systems biology in order to gain knowledge about complex and not directly observable cellular processes. For quantitative analyses, not only experimental data, but also measurement errors, play a crucial role. The total measurement error of any analytical protocol is the result of an accumulation of single errors introduced by several processing steps. Here, we present a framework for the quantification of intracellular metabolites, including error propagation during metabolome sample processing. Focusing on one specific protocol, we comprehensively investigate all currently known and accessible factors that ultimately impact the accuracy of intracellular metabolite concentration data. All intermediate steps are modeled, and their uncertainty with respect to the final concentration data is rigorously quantified. Finally, on the basis of a comprehensive metabolome dataset of Corynebacterium glutamicum, an integrated error propagation analysis for all parts of the model is conducted, and the most critical steps for intracellular metabolite quantification are detected. PMID:24957773

Tillack, Jana; Paczia, Nicole; Noh, Katharina; Wiechert, Wolfgang; Noack, Stephan

2012-01-01

450

Insight into cross-talk between intra-amoebal pathogens  

PubMed Central

Background Amoebae are phagocytic protists where genetic exchanges might take place between amoeba-resistant bacteria. These amoebal pathogens are able to escape the phagocytic behaviour of their host. They belong to different bacterial phyla and often show a larger genome size than human-infecting pathogens. This characteristic is proposed to be the result of frequent gene exchanges with other bacteria that share a sympatric lifestyle and contrasts with the genome reduction observed among strict human pathogens. Results We sequenced the genome of a new amoebal pathogen, Legionella drancourtii, and compared its gene content to that of a Chlamydia-related bacterium, Parachlamydia acanthamoebae. Phylogenetic reconstructions identified seven potential horizontal gene transfers (HGTs) between the two amoeba-resistant bacteria, including a complete operon of four genes that encodes an ABC-type transporter. These comparisons pinpointed potential cases of gene exchange between P. acanthamoebae and Legionella pneumophila, as well as gene exchanges between other members of the Legionellales and Chlamydiales orders. Moreover, nine cases represent possible HGTs between representatives from the Legionellales or Chlamydiales and members of the Rickettsiales order. Conclusions This study identifies numerous gene exchanges between intracellular Legionellales and Chlamydiales bacteria, which could preferentially occur within common inclusions in their amoebal hosts. Therefore it contributes to improve our knowledge on the intra-amoebal gene properties associated to their specific lifestyle. PMID:22047552

2011-01-01

451

Fungal pathogens of Proteaceae.  

PubMed

Species of Leucadendron, Leucospermum and Protea (Proteaceae) are in high demand for the international floriculture market due to their brightly coloured and textured flowers or bracts. Fungal pathogens, however, create a serious problem in cultivating flawless blooms. The aim of the present study was to characterise several of these pathogens using morphology, culture characteristics, and DNA sequence data of the rRNA-ITS and LSU genes. In some cases additional genes such as TEF 1-? and CHS were also sequenced. Based on the results of this study, several novel species and genera are described. Brunneosphaerella leaf blight is shown to be caused by three species, namely B. jonkershoekensis on Protea repens, B. nitidae sp. nov. on Protea nitida and B. protearum on a wide host range of Protea spp. (South Africa). Coniothyrium-like species associated with Coniothyrium leaf spot are allocated to other genera, namely Curreya grandicipis on Protea grandiceps, and Microsphaeropsis proteae on P. nitida (South Africa). Diaporthe leucospermi is described on Leucospermum sp. (Australia), and Diplodina microsperma newly reported on Protea sp. (New Zealand). Pyrenophora blight is caused by a novel species, Pyrenophora leucospermi, and not Drechslera biseptata or D. dematoidea as previously reported. Fusicladium proteae is described on Protea sp. (South Africa), Pestalotiopsis protearum on Leucospermum cuneiforme (Zimbabwe), Ramularia vizellae and R. stellenboschensis on Protea spp. (South Africa), and Teratosphaeria capensis on Protea spp. (Portugal, South Africa). Aureobasidium leaf spot is shown to be caused by two species, namely A. proteae comb. nov. on Protea spp. (South Africa), and A. leucospermi sp. nov. on Leucospermum spp. (Indonesia, Portugal, South Africa). Novel genera and species elucidated in this study include Gordonomyces mucovaginatus and Pseudopassalora gouriqua (hyphomycetes), and Xenoconiothyrium catenata (coelomycete), all on Protea spp. (South Africa). PMID:22403475

Crous, P W; Summerell, B A; Swart, L; Denman, S; Taylor, J E; Bezuidenhout, C M; Palm, M E; Marincowitz, S; Groenewald, J Z

2011-12-01

452

Rapid Detection of Pathogens  

SciTech Connect

Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development and the Perlin lab in sample preparation and testing in animal models.

David Perlin

2005-08-14

453

Transcriptional regulation by Ferric Uptake Regulator (Fur) in pathogenic bacteria.  

PubMed

In the ancient anaerobic environment, ferrous iron (Fe(2+)) was one of the first metal cofactors. Oxygenation of the ancient world challenged bacteria to acquire the insoluble ferric iron (Fe(3+)) and later to defend against reactive oxygen species (ROS) generated by the Fenton chemistry. To acquire Fe(3+), bacteria produce low-molecular weight compounds, known as siderophores, which have extremely high affinity for Fe(3+). However, during infection the host restricts iron from pathogens by producing iron- and siderophore-chelating proteins, by exporting iron from intracellular pathogen-containing compartments, and by limiting absorption of dietary iron. Ferric Uptake Regulator (Fur) is a transcription factor which utilizes Fe(2+) as a corepressor and represses siderophore synthesis in pathogens. Fur, directly or indirectly, controls expression of enzymes that protect against ROS damage. Thus, the challenges of iron homeostasis and defense against ROS are addressed via Fur. Although the role of Fur as a repressor is well-documented, emerging evidence demonstrates that Fur can function as an activator. Fur activation can occur through three distinct mechanisms (1) indirectly via small RNAs, (2) binding at cis regulatory elements that enhance recruitment of the RNA polymerase holoenzyme (RNAP), and (3) functioning as an antirepressor by removing or blocking DNA binding of a repressor of transcription. In addition, Fur homologs control defense against peroxide stress (PerR) and control uptake of other metals such as zinc (Zur) and manganese (Mur) in pathogenic bacteria. Fur family members are important for virulence within bacterial pathogens since mutants of fur, perR, or zur exhibit reduced virulence within numerous animal and plant models of infection. This review focuses on the breadth of Fur regulation in pathogenic bacteria. PMID:24106689

Troxell, Bryan; Hassan, Hosni M

2013-01-01

454

Intracellular diffusion restrictions in isolated cardiomyocytes from rainbow trout  

Microsoft Academic Search

BACKGROUND: Restriction of intracellular diffusion of adenine nucleotides has been studied intensively on adult rat cardiomyocytes. However, their cause and role in vivo is still uncertain. Intracellular membrane structures have been suggested to play a role. We therefore chose to study cardiomyocytes from rainbow trout (Oncorhynchus mykiss), which are thinner and have fewer intracellular membrane structures than adult rat cardiomyocytes.

Niina Sokolova; Marko Vendelin; Rikke Birkedal

2009-01-01

455

42 CFR 62.29 - Under what circumstances can the Loan Repayment Program obligation be discharged in bankruptcy?  

Code of Federal Regulations, 2010 CFR

...Repayment Program obligation be discharged in bankruptcy? 62.29 Section 62.29 Public...Repayment Program obligation be discharged in bankruptcy? Any payment obligation incurred...subpart may be released by a discharge in bankruptcy under title 11 of the United...

2010-10-01

456

66 FR 20659 - Notice of New Exposure Draft Change in Certain Requirements for Reconciling Obligations and Net...  

Federal Register 2010, 2011, 2012, 2013

...Requirements for Reconciling Obligations and Net Cost of Operations--Amendment of SFFAS...Requirements for Reconciling Obligations and Net Cost of Operations--Amendment to SFFAS...the reconciliation of obligations and the net cost of operations in the statement of...

2001-04-24

457

Methylophilus quaylei sp. nov., a new aerobic obligately methylotrophic bacterium.  

PubMed

A new obligately methylotrophic bacterium (strain MTT) with the ribulose monophosphate pathway of carbon assimilation is described. The isolate, utilizing only methanol, is an aerobic, Gram-negative, asporogenous, non-motile short rod multiplying by binary fission. Its cellular fatty acids profile consists primarily of straight-chain saturated C16:0 and unsaturated C16:l acids. The major ubiquinone is Q-8. The dominant phospholipids are phosphatidylethanolamine and phosphatidylglycerol. Diphosphatidylglycerol (cardiolipin) is absent. Optimal growth conditions are 25-29 degree C, pH 6.5 - 7.5, 0.5% CH3OH and 0.05% NaCl. Strain MTT lacks alpha-ketoglutarate dehydrogenase, the glyoxylate shunt enzymes, and glutamate dehydrogenase. Ammonium is assimilated by the operation of the glutamate cycle enzymes: glutamine synthetase and glutamate synthase. An exopolysaccharide consisting of rhamnose, glucose and galactose is formed under nitrogen limitation. The G + C content of the DNA is 54.0 mol%. Based on 16S rDNA sequence analysis and DNA-DNA relatedness (29-34%) with type strains of the genus Methylophilus, the novel isolate was classified as a new species of this genus and named Methylophilus quaylei MTT (VKM B-2338T, DSMZ, etc.). PMID:15997702

Doronina, Nina; Ivanova, Ekaterina; Trotsenko, Yuri; Pshenichnikova, Anna; Kalinina, Ekaterina; Shvets, Vitaly

2005-06-01

458

Health facilities' obligations when a patient refuses treatment.  

PubMed

Recent cases involving the decisions of Elizabeth Bouvia and G. Ross Henninger to starve themselves to death highlight the ethical obligations of patients, health care facilities, and the courts. When a patient seeks the hospital's cooperation in his or her attempt to commit suicide, society's responsibility is not merely to restrain the patient from suicide but to offer physical care, financial aid, and personal support. The hospital's duty is to intervene, and the court's responsibility is to allow such intervention. The most compassionate way in which the hospital can help is to force-feed the patient. If a patient is mentally competent, the refusal to eat is morally wrong. The patient is morally not permitted to commit suicide, though the avoidance of treatment may be justified in cases when force-feeding would be considered an extraordinary means, because of the patient's age or physical condition, for example. If a patient is incompetent, the refusal to eat is not a fully rational act; for the hospital to refrain from force-feeding would not be considered cooperation in suicide, since the incompetent patient cannot commit suicide. To avoid court rulings that order compliance with a patient's wishes, health care facilities in the future may have to require patients or their families to agree in writing to treatment by ordinary means. PMID:10268324

Gallagher, J

1984-09-01

459