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1

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

, and signaling [1]. We report that infection with the obligate intracellular pathogen Chlamydia trachomatis.cub.2006.06.060 Report The Obligate Intracellular Pathogen Chlamydia trachomatis Targets Host Lipid of neutral-lipid-rich struc- tures with features of LDs at the cytoplasmic surface of the bacteria

Valdivia, Raphael

2

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

3

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

4

A MyD88-Dependent Early IL-17 Production Protects Mice against Airway Infection with the Obligate Intracellular Pathogen Chlamydia muridarum1  

PubMed Central

We found that IL-17, a signature cytokine of Th17, was produced early in the innate immunity phase after an intranasal infection with the obligate intracellular pathogen Chlamydia muridarum. The airway IL-17, which peaked at 48 h after infection, was dependent on live chlamydial organism replication and MyD88-mediated signaling pathways. Treatment with antibiotics or knockout of the MyD88 gene, but not Toll/IL receptor domain-containing adapter-inducing IFN-?, can block the early IL-17 production. Treatment of mice with an anti-IL-17-neutralizing mAb enhanced growth of chlamydial organisms in the lung, dissemination to other organs, and decreased mouse survival, whereas treatment with an isotype-matched control IgG had no effect. Although IL-17 did not directly affect chlamydial growth in cell culture, it enhanced the production of other inflammatory cytokines and chemokines by Chlamydia-infected cells and promoted neutrophil infiltration in mouse airways during chlamydial infection, which may contribute to the antichlamydial effect of IL-17. These observations suggest that an early IL-17 response as an innate immunity component plays an important role in initiating host defense against infection with intracellular bacterial pathogens in the airway. PMID:19542374

Zhang, Xiaoyun; Gao, Lifen; Lei, Lei; Zhong, Youmin; Dube, Peter; Berton, Michael T.; Arulanandam, Bernard; Zhang, Jinshun; Zhong, Guangming

2009-01-01

5

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

6

Molecular pathogenesis of the obligate intracellular bacterium Coxiella burnetii  

PubMed Central

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

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

2014-01-01

7

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

8

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

E-print Network

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

Bordenstein, Seth

9

Multi locus sequence typing of Chlamydiales: clonal groupings within the obligate intracellular bacteria Chlamydia trachomatis  

Microsoft Academic Search

BACKGROUND: The obligate intracellular growing bacterium Chlamydia trachomatis causes diseases like trachoma, urogenital infection and lymphogranuloma venereum with severe morbidity. Several serovars and genotypes have been identified, but these could not be linked to clinical disease or outcome. The related Chlamydophila pneumoniae, of which no subtypes are recognized, causes respiratory infections worldwide. We developed a multi locus sequence typing (MLST)

Yvonne Pannekoek; Giovanna Morelli; Barica Kusecek; Servaas A Morré; Jacobus M Ossewaarde; Ankie A Langerak; Arie van der Ende

2008-01-01

10

Transposon Mutagenesis of the Obligate Intracellular Pathogen Rickettsia prowazekii  

Microsoft Academic Search

Genetic analysis of Rickettsia prowazekii has been hindered by the lack of selectable markers and efficient mechanisms for generating rickettsial gene knockouts. We have addressed these problems by adapting a gene that codes for rifampin resistance for expression in R. prowazekii and by incorporating this selection into a transposon mutagenesis system suitable for generating rickettsial gene knockouts. The arr-2 gene

Aiping Qin; Aimee M. Tucker; Andria Hines; David O. Wood

2004-01-01

11

Nramp1: a link between intracellular iron transport and innate resistance to intracellular pathogens  

Microsoft Academic Search

Nramp1 (natural resistance-associated macrophage protein one) regulates intracellular pathogen proliferation and macrophage inflamma- tory responses. Murine Nramp1 exhibits a natural polymorphism with alleles termed resistant and susceptible. Alleles restrict or allow the prolifera- tion of intracellular pathogens, respectively. Struc- tural predictions suggest that Nramp1 encodes the prototypic member of a transporter family. Nramp1 exhibits sequence identity to Nramp2, which regu-

C. Howard Barton; Thelma E. Biggs; Stephen T. Baker; Holly Bowen; Peter G. P. Atkinson

1999-01-01

12

Caenorhabditis elegans as a model for intracellular pathogen infection  

PubMed Central

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

Balla, Keir M.; Troemel, Emily R.

2014-01-01

13

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

14

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

PubMed Central

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

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

2010-01-01

15

Bacterial Pathogens Commandeer Rab GTPases to Establish Intracellular Niches  

PubMed Central

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

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

2012-01-01

16

Manipulation of costimulatory molecules by intracellular pathogens: veni, vidi, vici!!  

PubMed

Some of the most successful pathogens of human, such as Mycobacterium tuberculosis (Mtb), HIV, and Leishmania donovani not only establish chronic infections but also remain a grave global threat. These pathogens have developed innovative strategies to evade immune responses such as antigenic shift and drift, interference with antigen processing/presentation, subversion of phagocytosis, induction of immune regulatory pathways, and manipulation of the costimulatory molecules. Costimulatory molecules expressed on the surface of various cells play a decisive role in the initiation and sustenance of immunity. Exploitation of the "code of conduct" of costimulation pathways provides evolutionary incentive to the pathogens and thereby abates the functioning of the immune system. Here we review how Mtb, HIV, Leishmania sp., and other pathogens manipulate costimulatory molecules to establish chronic infection. Impairment by pathogens in the signaling events delivered by costimulatory molecules may be responsible for defective T-cell responses; consequently organisms grow unhindered in the host cells. This review summarizes the convergent devices that pathogens employ to tune and tame the immune system using costimulatory molecules. Studying host-pathogen interaction in context with costimulatory signals may unveil the molecular mechanism that will help in understanding the survival/death of the pathogens. We emphasize that the very same pathways can potentially be exploited to develop immunotherapeutic strategies to eliminate intracellular pathogens. PMID:22719245

Khan, Nargis; Gowthaman, Uthaman; Pahari, Susanta; Agrewala, Javed N

2012-01-01

17

Glutathione activates virulence gene expression of an intracellular pathogen.  

PubMed

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

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

2015-01-01

18

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

19

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, Jürgen; Rudel, Thomas; Goebel, Werner

2013-01-01

20

Specific isolation of RNA from the grape powdery mildew pathogen Erysiphe necator, an epiphytic, obligate parasite  

Technology Transfer Automated Retrieval System (TEKTRAN)

RNA expression profiling of obligately parasitic plant microbes is hampered by the requisite interaction of host and parasite. For superficial pathogens like grape powdery mildew as well as for epiphytic saprophytes, growth along the outside surface of the plant allows separation from the host and ...

21

Interleukin-10 and Immunity against Prokaryotic and Eukaryotic Intracellular Pathogens ?  

PubMed Central

The generation of an effective immune response against an infection while also limiting tissue damage requires a delicate balance between pro- and anti-inflammatory responses. Interleukin-10 (IL-10) has potent immunosuppressive effects and is essential for regulation of immune responses. However, the immunosuppressive properties of IL-10 can also be exploited by pathogens to facilitate their own survival. In this minireview, we discuss the role of IL-10 in modulating intracellular bacterial, fungal, and parasitic infections. Using information from several different infection models, we bring together and highlight some common pathways for IL-10 regulation and function that cannot be fully appreciated by studies of a single pathogen. PMID:21576331

Cyktor, Joshua C.; Turner, Joanne

2011-01-01

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

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

PubMed

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

2014-08-01

24

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

PubMed Central

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

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

2012-01-01

25

Analysis of Fluorescent Protein Expression in Transformants of Rickettsia monacensis, an Obligate Intracellular Tick Symbiont  

PubMed Central

We developed and applied transposon-based transformation vectors for molecular manipulation and analysis of spotted fever group rickettsiae, which are obligate intracellular bacteria that infect ticks and, in some cases, mammals. Using the Epicentre EZ::TN transposon system, we designed transposons for simultaneous expression of a reporter gene and a chloramphenicol acetyltransferase (CAT) resistance marker. Transposomes (transposon-transposase complexes) were electroporated into Rickettsia monacensis, a rickettsial symbiont isolated from the tick Ixodes ricinus. Each transposon contained an expression cassette consisting of the rickettsial ompA promoter and a green fluorescent protein (GFP) reporter gene (GFPuv) or the ompB promoter and a red fluorescent protein reporter gene (DsRed2), followed by the ompA transcription terminator and a second ompA promoter CAT gene cassette. Selection with chloramphenicol gave rise to rickettsial populations with chromosomally integrated single-copy transposons as determined by PCR, Southern blotting, and sequence analysis. Reverse transcription-PCR and Northern blots demonstrated transcription of all three genes. GFPuv transformant rickettsiae exhibited strong fluorescence in individual cells, but DsRed2 transformants did not. Western blots confirmed expression of GFPuv in R. monacensis and in Escherichia coli, but DsRed2 was expressed only in E. coli. The DsRed2 gene, but not the GFPuv gene, contains many GC-rich amino acid codons that are rare in the preferred codon suite of rickettsiae, possibly explaining the failure to express DsRed2 protein in R. monacensis. We demonstrated that our vectors provide a means to study rickettsia-host cell interactions by visualizing GFPuv-fluorescent R. monacensis associated with actin tails in tick host cells. PMID:15812043

Baldridge, Gerald D.; Burkhardt, Nicole; Herron, Michael J.; Kurtti, Timothy J.; Munderloh, Ulrike G.

2005-01-01

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

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

2014-01-01

27

Infection of zebrafish embryos with intracellular bacterial pathogens.  

PubMed

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

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

2012-01-01

28

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

PubMed Central

We have developed a vaccine strategy for generating an attenuated strain of an intracellular bacterial pathogen that, after uptake by professional antigen-presenting cells, does not replicate intracellularly and is readily killed. However, after degradation of the vaccine strain within the phagolysosome, target antigens are released into the cytosol for endogenous processing and presentation for stimulation of CD8+ effector T cells. Applying this strategy to the model intracellular pathogen Listeria monocytogenes, we show that an intracellular replication-deficient vaccine strain is cleared rapidly in normal and immunocompromised animals, yet antigen-specific CD8+ effector T cells are stimulated after immunization. Furthermore, animals immunized with the intracellular replication-deficient vaccine strain are resistant to lethal challenge with a virulent WT strain of L. monocytogenes. These studies suggest a general strategy for developing safe and effective, attenuated intracellular replication-deficient vaccine strains for stimulation of protective immune responses against intracellular bacterial pathogens. PMID:16549792

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

2006-01-01

29

Actin-Based Motility of Intracellular Microbial Pathogens  

PubMed Central

A diverse group of intracellular microorganisms, including Listeria monocytogenes, Shigella spp., Rickettsia spp., and vaccinia virus, utilize actin-based motility to move within and spread between mammalian host cells. These organisms have in common a pathogenic life cycle that involves a stage within the cytoplasm of mammalian host cells. Within the cytoplasm of host cells, these organisms activate components of the cellular actin assembly machinery to induce the formation of actin tails on the microbial surface. The assembly of these actin tails provides force that propels the organisms through the cell cytoplasm to the cell periphery or into adjacent cells. Each of these organisms utilizes preexisting mammalian pathways of actin rearrangement to induce its own actin-based motility. Particularly remarkable is that while all of these microbes use the same or overlapping pathways, each intercepts the pathway at a different step. In addition, the microbial molecules involved are each distinctly different from the others. Taken together, these observations suggest that each of these microbes separately and convergently evolved a mechanism to utilize the cellular actin assembly machinery. The current understanding of the molecular mechanisms of microbial actin-based motility is the subject of this review. PMID:11729265

Goldberg, Marcia B.

2001-01-01

30

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

PubMed Central

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

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

2012-01-01

31

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

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

2014-01-01

32

Manipulation of Costimulatory Molecules by Intracellular Pathogens: Veni, Vidi, Vici!!  

Microsoft Academic Search

Some of the most successful pathogens of human, such as Mycobacterium tuberculosis (Mtb), HIV, and Leishmania donovani not only establish chronic infections but also remain a grave global threat. These pathogens have developed innovative strategies to evade immune responses such as antigenic shift and drift, interference with antigen processing\\/presentation, subversion of phagocytosis, induction of immune regulatory pathways, and manipulation of

Nargis Khan; Uthaman Gowthaman; Susanta Pahari; Javed N. Agrewala

2012-01-01

33

Human blood monocytes support persistence, but not replication of the intracellular pathogen C. pneumoniae.  

PubMed

BackgroundIntracellular pathogens have devised various mechanisms to subvert the host immune response in order to survive and replicate in host cells. Here, we studied the infection of human blood monocytes with the intracellular pathogen C. pneumoniae and the effect on cytokine and chemokine profiles in comparison to stimulation with LPS.ResultsMonocytes purified from peripheral blood mononuclear cells by negative depletion were infected with C. pneumoniae. While immunofluorescence confirmed the presence of chlamydial lipopolysaccharide (LPS) in the cytoplasm of infected monocytes, real-time PCR did not provide evidence for replication of the intracellular pathogen. Complementary to PCR, C. pneumoniae infection was confirmed by an oligonucleotide DNA microarray for the detection of intracellular pathogens. Raman microspectroscopy revealed different molecular fingerprints for infected and non-infected monocytes, which were mainly due to changes in lipid and fatty acid content. Stimulation of monocytes with C. pneumoniae or with LPS induced similar profiles of tumor necrosis factor-alpha (TNF-¿) and interleukin (IL)-6, but higher levels of IL-1ß, IL-12p40 and IL-12p70 for C. pneumoniae which were statistically significant. C. pneumoniae also induced release of the chemokines MCP-1, MIP-1¿ and MIP-1ß, and CXCL-8, which correlated with TNF-¿ secretion.ConclusionInfection of human blood monocytes with intracellular pathogens triggers altered cytokine and chemokine pattern as compared to stimulation with extracellular ligands such as LPS. Complementing conventional methods, an oligonucleotide DNA microarray for the detection of intracellular pathogens as well as Raman microspectroscopy provide useful tools to trace monocyte infection. PMID:25488836

Buchacher, Tanja; Wiesinger-Mayr, Herbert; Vierlinger, Klemens; Rüger, Beate M; Stanek, Gerold; Fischer, Michael B; Weber, Viktoria

2014-12-01

34

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

PubMed Central

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

2014-01-01

35

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

36

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

37

The Intracellular Pathogen Rhodococcus equi Produces a Catecholate Siderophore Required for Saprophytic Growth  

Microsoft Academic Search

Little is known about the iron acquisition systems of the soilborne facultative intracellular pathogen Rhodococcus equi. We previously reported that expression of iupABC, encoding a putative siderophore ABC transporter system, is iron regulated and required for growth at low iron concentrations. Here we show that disruption of iupA leads to the concomitant accumulation of catecholates and a chromophore with absorption

Raul Miranda-CasoLuengo; John F. Prescott; J. A. Vazquez-Boland; W. G. Meijer

2008-01-01

38

Delivery of host cell-directed therapeutics for intracellular pathogen clearance  

PubMed Central

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

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

2014-01-01

39

Infected Dendritic Cells Facilitate Systemic Dissemination and Transplacental Passage of the Obligate Intracellular Parasite Neospora caninum in Mice  

PubMed Central

The obligate intracellular parasite Neospora caninum disseminates across the placenta and the blood-brain barrier, to reach sites where it causes severe pathology or establishes chronic persistent infections. The mechanisms used by N. caninum to breach restrictive biological barriers remain elusive. To examine the cellular basis of these processes, migration of different N. caninum isolates (Nc-1, Nc-Liverpool, Nc-SweB1 and the Spanish isolates: Nc-Spain 3H, Nc-Spain 4H, Nc-Spain 6, Nc-Spain 7 and Nc-Spain 9) was studied in an in vitro model based on a placental trophoblast-derived BeWo cell line. Here, we describe that infection of dendritic cells (DC) by N. caninum tachyzoites potentiated translocation of parasites across polarized cellular monolayers. In addition, powered by the parasite's own gliding motility, extracellular N. caninum tachyzoites were able to transmigrate across cellular monolayers. Altogether, the presented data provides evidence of two putative complementary pathways utilized by N. caninum, in an isolate-specific fashion, for passage of restrictive cellular barriers. Interestingly, adoptive transfer of tachyzoite-infected DC in mice resulted in increased parasitic loads in various organs, e.g. the central nervous system, compared to infections with free parasites. Inoculation of pregnant mice with infected DC resulted in an accentuated vertical transmission to the offspring with increased parasitic loads and neonatal mortality. These findings reveal that N. caninum exploits the natural cell trafficking pathways in the host to cross cellular barriers and disseminate to deep tissues. The findings are indicative of conserved dissemination strategies among coccidian apicomplexan parasites. PMID:22403627

Collantes-Fernandez, Esther; Arrighi, Romanico B. G.; Álvarez-García, Gema; Weidner, Jessica M.; Regidor-Cerrillo, Javier; Boothroyd, John C.; Ortega-Mora, Luis M.; Barragan, Antonio

2012-01-01

40

Type IV Pili in Francisella – A Virulence Trait in an Intracellular Pathogen  

PubMed Central

Francisella tularensis is a highly virulent intracellular human pathogen that is capable of rapid proliferation in the infected host. Mutants affected in intracellular survival and growth are highly attenuated which highlights the importance of the intracellular phase of the infection. Genomic analysis has revealed that Francisella encodes all genes required for expression of functional type IV pili (Tfp), and in this focused review we summarize recent findings regarding this system in the pathogenesis of tularemia. Tfp are dynamic adhesive structures that have been identified as major virulence determinants in several human pathogens, but it is not obvious what role these structures could have in an intracellular pathogen like Francisella. In the human pathogenic strains, genes required for secretion and assembly of Tfp and one pilin, PilA, have shown to be required for full virulence. Importantly, specific genetic differences have been identified between the different Francisella subspecies where in the most pathogenic type A variants all genes are intact while several Tfp genes are pseudogenes in the less pathogenic type B strains. This suggests that there has been a selection for expression of Tfp with different properties in the different subspecies. There is also a possibility that the genetic differences reflect adaptation to different environmental niches of the subspecies and plays a role in transmission of tularemia. This is also in line with recent findings where Tfp pilins are found to be glycosylated which could reflect a role for Tfp in the environment to promote survival and transmission. We are still far from understanding the role of Tfp in virulence and transmission of tularemia, but with the genomic information and genetic tools available we are in a good position to address these issues in the future. PMID:21687421

Salomonsson, Emelie Näslund; Forslund, Anna-Lena; Forsberg, Åke

2011-01-01

41

Gene Gain and Loss during Evolution of Obligate Parasitism in the White Rust Pathogen of Arabidopsis thaliana  

PubMed Central

Biotrophic eukaryotic plant pathogens require a living host for their growth and form an intimate haustorial interface with parasitized cells. Evolution to biotrophy occurred independently in fungal rusts and powdery mildews, and in oomycete white rusts and downy mildews. Biotroph evolution and molecular mechanisms of biotrophy are poorly understood. It has been proposed, but not shown, that obligate biotrophy results from (i) reduced selection for maintenance of biosynthetic pathways and (ii) gain of mechanisms to evade host recognition or suppress host defence. Here we use Illumina sequencing to define the genome, transcriptome, and gene models for the obligate biotroph oomycete and Arabidopsis parasite, Albugo laibachii. A. laibachii is a member of the Chromalveolata, which incorporates Heterokonts (containing the oomycetes), Apicomplexa (which includes human parasites like Plasmodium falciparum and Toxoplasma gondii), and four other taxa. From comparisons with other oomycete plant pathogens and other chromalveolates, we reveal independent loss of molybdenum-cofactor-requiring enzymes in downy mildews, white rusts, and the malaria parasite P. falciparum. Biotrophy also requires “effectors” to suppress host defence; we reveal RXLR and Crinkler effectors shared with other oomycetes, and also discover and verify a novel class of effectors, the “CHXCs”, by showing effector delivery and effector functionality. Our findings suggest that evolution to progressively more intimate association between host and parasite results in reduced selection for retention of certain biosynthetic pathways, and particularly reduced selection for retention of molybdopterin-requiring biosynthetic pathways. These mechanisms are not only relevant to plant pathogenic oomycetes but also to human pathogens within the Chromalveolata. PMID:21750662

Kemen, Eric; Gardiner, Anastasia; Schultz-Larsen, Torsten; Kemen, Ariane C.; Balmuth, Alexi L.; Robert-Seilaniantz, Alexandre; Bailey, Kate; Holub, Eric; Studholme, David J.; MacLean, Dan; Jones, Jonathan D. G.

2011-01-01

42

The intracellular pathogen Orientia tsutsugamushi responsible for scrub typhus induces lipid droplet formation in mouse fibroblasts.  

PubMed

Mammalian cells store excess fatty acids in the form of triglycerides within lipid droplets. The intracellular bacterium Orientia tsutsugamush is the causative agent of severe human rickettiosis. We found that O. tsutsugamushi infection induces the formation of lipid droplets in mouse L-929 fibroblasts. In infected cells, a parallel increase in the number of lipid droplets and pathogens was observed. Interestingly, the pathogen-infection induced the accumulation of triglycerides even without external supply of fatty acids. These results suggest that O. tsutsugamushi alters lipid metabolism of host cells to induce lipid droplets. PMID:25251025

Ogawa, Motohiko; Fukasawa, Masayoshi; Satoh, Masaaki; Hanada, Kentaro; Saijo, Masayuki; Uchiyama, Tsuneo; Ando, Shuji

2014-11-01

43

Intracellular antibody-bound pathogens stimulate immune signaling via Fc-receptor TRIM21  

PubMed Central

Antibodies can be carried into the cell during pathogen infection where they are detected by the ubiquitously expressed cytosolic antibody receptor TRIM21. Here we show that TRIM21 recognition of intracellular antibodies activates immune signaling. TRIM21 catalyses K63-ubiquitin chain formation, stimulating transcription factor pathways NF-?B, AP-1 and IRF3, IRF5, IRF7. Activation results in proinflammatory cytokine production, modulation of natural killer (NK) stress ligands and the induction of an antiviral state. Intracellular antibody signaling is abrogated by genetic deletion of TRIM21 and is recovered by ectopic TRIM21 expression. Antibody sensing by TRIM21 can be stimulated upon infection by DNA or RNA non-enveloped viruses or intracellular bacteria. The antibody-TRIM21 detection system provides potent, comprehensive innate immune activation, independent of known pattern recognition receptors. PMID:23455675

McEwan, W.A; Tam, J.C.H; Watkinson, R.E; Bidgood, S.R; Mallery, D.L; James, L.C

2013-01-01

44

Molecular methods to investigate adhesion, transmigration, invasion and intracellular survival of the foodborne pathogen Campylobacter jejuni.  

PubMed

Campylobacter jejuni is a spiral-shaped Gram-negative pathogen and major agent of gastrointestinal foodborne illness in humans worldwide. This pathogen encodes numerous described pathogenicity-associated factors involved in important processes including bacterial adhesion to, transmigration across, invasion into and intracellular survival within intestinal epithelial cells. This review article highlights various molecular techniques applied in the studies of each of these individual steps of C. jejuni host cell interactions in vitro including gentamicin protection assay, chemotaxis and motility assays, transwell and intracellular survival assays, G-Lisa, siRNA knockdown, immunohistochemistry, immunofluorescence, electron microscopy and luciferase reporter assays. We discuss the strengths and limitations of the methods as well as the different cell model systems applied. Future work should employ new technologies including modern microscopic, proteomics-based and cell signaling approaches to identify and characterise novel virulence mechanisms, which are crucial to provide fresh insights into the diversity of strategies employed by this important pathogen to cause disease. PMID:23872466

Backert, Steffen; Hofreuter, Dirk

2013-10-01

45

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, Götz; Kumlehn, Jochen; Schweizer, Patrick

2010-01-01

46

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

47

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

48

Antigen selection based on expression levels during infection facilitates vaccine development for an intracellular pathogen  

PubMed Central

Vaccines effective against intracellular pathogens could save the lives of millions of people every year, but vaccine development has been hampered by the slow largely empirical search for protective antigens. In vivo highly expressed antigens might represent a small attractive antigen subset that could be rapidly evaluated, but experimental evidence supporting this rationale, as well as practical strategies for its application, is largely lacking because of technical difficulties. Here, we used Salmonella strains expressing differential amounts of a fluorescent model antigen during infection to show that, in a mouse typhoid fever model, CD4 T cells preferentially recognize abundant Salmonella antigens. To identify a large number of natural Salmonella antigens with high expression levels during infection, we used a quantitative in vivo screening strategy. Immunization studies with five particularly attractive candidates revealed two highly protective antigens that might permit the development of an improved typhoid fever vaccine. In conclusion, we have established a rationale and an experimental strategy that will substantially facilitate vaccine development for Salmonella and possibly other intracellular pathogens. PMID:15173591

Rollenhagen, Claudia; Sörensen, Meike; Rizos, Konstantin; Hurvitz, Robert; Bumann, Dirk

2004-01-01

49

Epigenetic Regulation of the Nitrosative Stress Response and Intracellular Macrophage Survival by Extraintestinal Pathogenic Escherichia coli  

PubMed Central

Summary Extraintestinal pathogenic Escherichia coli (ExPEC) reside in the enteric tract as a commensal reservoir, but can transition to a pathogenic state by invading normally sterile niches, establishing infection, and disseminating to invasive sites like the bloodstream. Macrophages are required for ExPEC dissemination, suggesting the pathogen has developed mechanisms to persist within professional phagocytes. Here, we report that FimX, an ExPEC-associated DNA invertase that regulates the major virulence factor type 1 pili (T1P), is also an epigenetic regulator of a LuxR-like response regulator HyxR. FimX regulated hyxR expression through bidirectional phase inversion of its promoter region at sites different from the type 1 pili promoter and independent of integration host factor IHF. In vitro, transition from high to low HyxR expression produced enhanced tolerance of reactive nitrogen intermediates (RNI), primarily through de-repression of hmpA, encoding a nitric oxide detoxifying flavohemoglobin. However, in the macrophage, HyxR produced large effects on intracellular survival in the presence and absence of RNI and independent of Hmp. Collectively, we have shown that the ability of ExPEC to survive in macrophages is contingent upon the proper transition from high to low HyxR expression through epigenetic regulatory control by FimX. PMID:22221182

Bateman, Stacey L.; Seed, Patrick C.

2013-01-01

50

The "domino theory" of gene death: gradual and mass gene extinction events in three lineages of obligate symbiotic bacterial pathogens.  

PubMed

During the adaptation of an organism to a parasitic lifestyle, various gene functions may be rendered superfluous due to the fact that the host may supply these needs. As a consequence, obligate symbiotic bacterial pathogens tend to undergo reductive genomic evolution through gene death (nonfunctionalization or pseudogenization) and deletion. Here, we examine the evolutionary sequence of gene-death events during the process of genome miniaturization in three bacterial species that have experienced extensive genome reduction: Mycobacterium leprae, Shigella flexneri, and Salmonella typhi. We infer that in all three lineages, the distribution of functional categories is similar in pseudogenes and genes but different from that of absent genes. Based on an analysis of evolutionary distances, we propose a two-step "domino effect" model for reductive genome evolution. The process starts with a gradual gene-by-gene-death sequence of events. Eventually, a crucial gene within a complex pathway or network is rendered nonfunctional triggering a "mass gene extinction" of the dependent genes. In contrast to published reports according to which genes belonging to certain functional categories are prone to nonfunctionalization more frequently and earlier than genes belonging to other functional categories, we could discern no characteristic regularity in the temporal order of function loss. PMID:16237210

Dagan, Tal; Blekhman, Ran; Graur, Dan

2006-02-01

51

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

PubMed Central

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

52

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

53

Molecular Evolutionary Consequences of Niche Restriction in Francisella tularensis, a Facultative Intracellular Pathogen  

PubMed Central

Francisella tularensis is a potent mammalian pathogen well adapted to intracellular habitats, whereas F. novicida and F. philomiragia are less virulent in mammals and appear to have less specialized lifecycles. We explored adaptations within the genus that may be linked to increased host association, as follows. First, we determined the genome sequence of F. tularensis subsp. mediasiatica, the only subspecies that had not been previously sequenced. This genome, and those of 12 other F. tularensis isolates, were then compared to the genomes of F. novicida (three isolates) and F. philomiragia (one isolate). Signs of homologous recombination were found in ?19.2% of F. novicida and F. philomiragia genes, but none among F. tularensis genomes. In addition, random insertions of insertion sequence elements appear to have provided raw materials for secondary adaptive mutations in F. tularensis, e.g. for duplication of the Francisella Pathogenicity Island and multiplication of a putative glycosyl transferase gene. Further, the five major genetic branches of F. tularensis seem to have converged along independent routes towards a common gene set via independent losses of gene functions. Our observations suggest that despite an average nucleotide identity of >97%, F. tularensis and F. novicida have evolved as two distinct population lineages, the former characterized by clonal structure with weak purifying selection, the latter by more frequent recombination and strong purifying selection. F. tularensis and F. novicida could be considered the same bacterial species, given their high similarity, but based on the evolutionary analyses described in this work we propose retaining separate species names. PMID:19521508

Larsson, Pär; Elfsmark, Daniel; Svensson, Kerstin; Wikström, Per; Forsman, Mats; Brettin, Thomas; Keim, Paul; Johansson, Anders

2009-01-01

54

13C-Flux Spectral Analysis of Host-Pathogen Metabolism Reveals a Mixed Diet for Intracellular Mycobacterium tuberculosis  

PubMed Central

Summary Whereas intracellular carbon metabolism has emerged as an attractive drug target, the carbon sources of intracellularly replicating pathogens, such as the tuberculosis bacillus Mycobacterium tuberculosis, which causes long-term infections in one-third of the world’s population, remain mostly unknown. We used a systems-based approach—13C-flux spectral analysis (FSA) complemented with manual analysis—to measure the metabolic interaction between M. tuberculosis and its macrophage host cell. 13C-FSA analysis of experimental data showed that M. tuberculosis obtains a mixture of amino acids, C1 and C2 substrates from its host cell. We experimentally confirmed that the C1 substrate was derived from CO2. 13C labeling experiments performed on a phosphoenolpyruvate carboxykinase mutant revealed that intracellular M. tuberculosis has access to glycolytic C3 substrates. These findings provide constraints for developing novel chemotherapeutics. PMID:23911587

Beste, Dany J.V.; Nöh, Katharina; Niedenführ, Sebastian; Mendum, Tom A.; Hawkins, Nathaniel D.; Ward, Jane L.; Beale, Michael H.; Wiechert, Wolfgang; McFadden, Johnjoe

2013-01-01

55

Rapid and Sensitive Detection of an Intracellular Pathogen in Human Peripheral Leukocytes with Hybridizing Magnetic Relaxation Nanosensors  

PubMed Central

Bacterial infections are still a major global healthcare problem. The quick and sensitive detection of pathogens responsible for these infections would facilitate correct diagnosis of the disease and expedite treatment. Of major importance are intracellular slow-growing pathogens that reside within peripheral leukocytes, evading recognition by the immune system and detection by traditional culture methods. Herein, we report the use of hybridizing magnetic nanosensors (hMRS) for the detection of an intracellular pathogen, Mycobacterium avium spp. paratuberculosis (MAP). The hMRS are designed to bind to a unique genomic sequence found in the MAP genome, causing significant changes in the sample’s magnetic resonance signal. Clinically relevant samples, including tissue and blood, were screened with hMRS and results were compared with traditional PCR analysis. Within less than an hour, the hMRS identified MAP-positive samples in a library of laboratory cultures, clinical isolates, blood and homogenized tissues. Comparison of the hMRS with culture methods in terms of prediction of disease state revealed that the hMRS outperformed established culture methods, while being significantly faster (1 hour vs 12 weeks). Additionally, using a single instrument and one nanoparticle preparation we were able to detect the intracellular bacterial target in clinical samples at the genomic and epitope levels. Overall, since the nanoparticles are robust in diverse environmental settings and substantially more affordable than PCR enzymes, the potential clinical and field-based use of hMRS in the multiplexed identification of microbial pathogens and other disease-related biomarkers via a single, deployable instrument in clinical and complex environmental samples is foreseen. PMID:22496916

Kaittanis, Charalambos; Boukhriss, Hamza; Santra, Santimukul; Naser, Saleh A.; Perez, J. Manuel

2012-01-01

56

A Rickettsia genome overrun by mobile genetic elements provides insight into the acquisition of genes characteristic of an obligate intracellular lifestyle.  

PubMed

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

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

2012-01-01

57

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

PubMed Central

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

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

2010-01-01

58

Intracellular Pathogen Leishmania donovani Activates Hypoxia Inducible Factor-1 by Dual Mechanism for Survival Advantage within Macrophage  

PubMed Central

Recent evidence established a crucial role for mammalian oxygen sensing transcription factor hypoxia inducible factor-1 (HIF-1) in innate immunity against intracellular pathogens. In response to most of these pathogens host phagocytes increase transcription of HIF-1?, the regulatory component of HIF-1 to express various effector molecules against invaders. Leishmania donovani (LD), a protozoan parasite and the causative agent of fatal visceral leishmaniasis resides in macrophages within mammalian host. The mechanism of HIF-1 activation or its role in determining the fate of LD in infected macrophages is still not known. To determine that J774 macrophages were infected with LD and about four-fold increase in HIF-1 activity and HIF-1? expression were detected. A strong increase in HIF-1? expression and nuclear localization was also detected in LD-infected J774 cells, peritoneal macrophages and spleen derived macrophages of LD-infected BALB/c mice. A two-fold increase in HIF-1? mRNA was detected in LD-infected macrophages suggesting involvement of a transcriptional mechanism that was confirmed by promoter activity. We further revealed that LD also induced HIF-1? expression by depleting host cellular iron pool to affect prolyl hydroxylase activity resulting in to stabilization of HIF-1?. To determine the role of HIF-1 on intracellular LD, cells were transfected with HIF-1? siRNA to attenuate its expression and then infected with LD. Although, initial infection rate of LD in HIF-1? attenuated cells was not affected but intracellular growth of LD was significantly inhibited; while, over-expression of stabilized form of HIF-1? promoted intracellular growth of LD in host macrophage. Our results strongly suggest that LD activates HIF-1 by dual mechanism for its survival advantage within macrophage. PMID:22701652

Singh, Amit Kumar; Mukhopadhyay, Chaitali; Biswas, Sudipta; Singh, Vandana Kumari; Mukhopadhyay, Chinmay K.

2012-01-01

59

Cellular and molecular host-pathogen interactions during Chlamydia pneumoniae infection  

Microsoft Academic Search

Chlamydia pneumoniae is a Gram-negative bacterial pathogen that has evolved to survive completely within the intracellular environment of a host cell. The obligate intracellular lifestyle of this bacterium necessitates an efficient invasion strategy, exemplified by a broad host cell tropism with little propensity for any single cell type and the ability to replicate within both professional phagocytic cells and cells

Brian Kenneth Coombes

2002-01-01

60

CELLULAR AND MOLECULAR HOST-PATHOGEN INTERACTIONS DURING CHLAMYDIA PNEUMONIAE INFECTION  

Microsoft Academic Search

Chlamydia pneumoniae is a Gram-negative bacterial pathogen that has evolved to survive completely within the intracellular environment of a host cell. The obligate intracellular lifestyle of this bacterium necessitates an efficient invasion strategy, exemplified by a broad host cell tropism with little propensity for any single cell type and the ability to replicate within both professional phagocytic cells and cells

Brian K Coombes

2002-01-01

61

Type II cytokines impair host defense against an intracellular fungal pathogen by amplifying macrophage generation of IL-33.  

PubMed

Interleukin (IL)-4 subverts protective immunity to multiple intracellular pathogens, including the fungus Histoplasma capsulatum. Previously, we reported that H. capsulatum-challenged CCR2(-/-) mice manifest elevated pulmonary fungal burden owing to exaggerated IL-4. Paradoxical to our anticipation in IL-33 driving IL-4, we discovered that the latter prompted IL-33 in mutant mice. In infected CCR2(-/-) animals, amplified IL-33 succeeded the heightened IL-4 response and inhibition of IL-4 signaling decreased IL-33. Moreover, macrophages, but not epithelial cells or dendritic cells, from these mice expressed higher IL-33 in comparison with controls. Dissection of mechanisms that promulgated IL-33 revealed type-II cytokines and H. capsulatum synergistically elicited an IL-33 response in macrophages via signal transducer and activator of transcription factor 6/interferon-regulatory factor-4 and Dectin-1 pathways, respectively. Neutralizing IL-33 in CCR2(-/-) animals, but not controls, enhanced their resistance to histoplasmosis. Thus we describe a previously unrecognized role for IL-4 in instigating IL-33 in macrophages. Furthermore, in the presence of intracellular fungal pathogens, the type-II cytokine-driven IL-33 response impairs immunity. PMID:25118166

Verma, A; Kroetz, D N; Tweedle, J L; Deepe, G S

2015-03-01

62

Dormant Intracellular Salmonella enterica Serovar Typhimurium Discriminates among Salmonella Pathogenicity Island 2 Effectors To Persist inside Fibroblasts  

PubMed Central

Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that the S. enterica serovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations. PMID:24144726

Núñez-Hernández, Cristina; Alonso, Ana; Pucciarelli, M. Graciela; Casadesús, Josep

2014-01-01

63

Dormant intracellular Salmonella enterica serovar Typhimurium discriminates among Salmonella pathogenicity island 2 effectors to persist inside fibroblasts.  

PubMed

Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that the S. enterica serovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations. PMID:24144726

Núñez-Hernández, Cristina; Alonso, Ana; Pucciarelli, M Graciela; Casadesús, Josep; García-del Portillo, Francisco

2014-01-01

64

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

65

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

Microsoft Academic Search

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

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

2005-01-01

66

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, Raúl; Turkenburg, Johan P.; Leech, Andrew P.; Walton, Paul H.; Murzin, Alexey G.; Meijer, Wim G.; Wilkinson, Anthony J.

2014-01-01

67

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

68

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

PubMed Central

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

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

2014-01-01

69

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

PubMed

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

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

2014-01-01

70

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

71

Characterization of two pathogenic mutations in cystathionine beta-synthase: different intracellular locations for wild-type and mutant proteins.  

PubMed

Cystathionine ?-synthase (CBS) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the condensation of homocysteine with serine to generate cystathionine. Homocystinuria is an autosomal recessive disorder commonly caused by a deficiency of CBS activity. Here, we characterized a novel CBS mutation (c.260C>A (p.T87N)) and a previously reported variant (c.700G>A (p.D234N)) found in Venezuelan homocystinuric patients, one nonresponsive and one responsive to vitamin B6. Both mutant proteins were expressed in vitro in prokaryotic and eukaryotic cells, finding lower soluble expression in HEK-293 cells (19% T87N and 23% D234N) compared to wild-type CBS. Residual activities obtained for the mutant proteins were 3.5% T87N and 43% D234N. Gel exclusion chromatography demonstrated a tendency of the T87N mutant to aggregate while the distribution of the D234N mutant was similar to wild-type enzyme. Using immunofluorescence microscopy, an unexpected difference in intracellular localization was observed between the wild-type and mutant proteins. While the T87N mutant exhibited a punctate appearance, the wild-type protein was homogeneously distributed inside the cell. Interestingly, the D234N protein showed both distributions. This study demonstrates that the pathogenic CBS mutations generate unstable proteins that are unable (T87N) or partially unable (D234N) to assemble into a functional enzyme, implying that these mutations might be responsible for the homocystinuria phenotype. PMID:23981774

Casique, L; Kabil, O; Banerjee, R; Martinez, J C; De Lucca, M

2013-11-15

72

Parasite Mitogen-Activated Protein Kinases as Drug Discovery Targets to Treat Human Protozoan Pathogens  

PubMed Central

Protozoan pathogens are a highly diverse group of unicellular organisms, several of which are significant human pathogens. One group of protozoan pathogens includes obligate intracellular parasites such as agents of malaria, leishmaniasis, babesiosis, and toxoplasmosis. The other group includes extracellular pathogens such as agents of giardiasis and amebiasis. An unfortunate unifying theme for most human protozoan pathogens is that highly effective treatments for them are generally lacking. We will review targeting protozoan mitogen-activated protein kinases (MAPKs) as a novel drug discovery approach towards developing better therapies, focusing on Plasmodia, Leishmania, and Toxoplasma, about which the most is known. PMID:21637385

Brumlik, Michael J.; Pandeswara, Srilakshmi; Ludwig, Sara M.; Murthy, Kruthi; Curiel, Tyler J.

2011-01-01

73

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

74

SR-A/MARCO-mediated ligand delivery enhances intracellular TLR and NLR function, but ligand scavenging from cell surface limits TLR4 response to pathogens.  

PubMed

Phagocytic and pathogen sensing receptors are responsible for particle uptake and inflammation. It is unclear how these receptors' systems influence each other's function to shape an innate response. The class-A scavenger receptors SR-A (scavenger receptor A) and MARCO (macrophage receptor with collagenous structure) are 2 well-characterized phagocytic receptors that are unable to initiate inflammatory responses by themselves, yet are implicated in the pathogenesis of various inflammatory disorders. However, the mechanism for such an apparent discrepancy is still unclear. We utilized SR-A(-/-), MARCO(-/-), and SR-A(-/-)-MARCO(-/-) mice, along with microbe-derived, environmental, and synthetic polyanions to assess the inflammatory responses following combinatorial ligation of SR-A/MARCO and selected Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) by their shared ligands. In addition to ligating SR-A and MARCO, these agonists also selectively activated the cell-surface sensor TLR4, endosomal TLR3, and the cytosolic NOD2 and NALP3 (NACHT domain-, leucine-rich repeat-, and pyrin domain-containing protein 3). We show that, following recognition of common ligands, SR-A and MARCO attenuate TLR4-mediated responses while enhancing responses by the intracellular TLR3, NOD2, and NALP3. We conclude that SR-A/MARCO-mediated rapid ligand internalization prevented sensing by surface TLRs while increasing ligand availability in intracellular compartments, thus allowing sensing and robust responses by intracellular sensors. PMID:21098741

Mukhopadhyay, Subhankar; Varin, Audrey; Chen, Yunying; Liu, Baoying; Tryggvason, Karl; Gordon, Siamon

2011-01-27

75

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

PubMed

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

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

2012-02-01

76

Characterisation and therapeutic modulation of toll-like receptor signalling in response to the intracellular pathogen F. tularensis  

E-print Network

containing vacuole FimH Fimbriae H protein FPI Francisella pathogenicity island GSK3B Glycogen synthase kinase-3B HDAC Histone deacetylase HLH Helix-loop-helix HMGB-1 High-mobility group box-1 HRP Horseradish peroxidase HSV Herpes simplex virus IFN...

Saint, Richard

2013-01-08

77

Gene Expression Profiles of Blumeria graminis Indicate Dynamic Changes to Primary Metabolism during Development of an Obligate Biotrophic PathogenW?  

PubMed Central

cDNA microarrays of Blumeria graminis f sp hordei transcript profiles during the asexual development cycle reveal the dynamics of global gene expression as the fungus germinates, penetrates, feeds on its host, and produces masses of conidia for dispersal. The expression profiles of genes encoding enzymes involved in primary metabolism show that there is a striking degree of coordinate regulation of some of the genes in the same pathway. In one example, genes encoding several glycolytic enzymes are significantly upregulated as mature appressoria form and also in infected epidermis, which contain fungal haustoria. In another example, mRNAs for lipid degrading enzymes are initially expressed at high levels in the conidia and the early germination stages and decrease significantly later. We discuss these results and draw inferences on the metabolic status of this obligate biotrophic fungus as it infects its host and completes its life cycle. PMID:15951491

Both, Maike; Csukai, Michael; Stumpf, Michael P.H.; Spanu, Pietro D.

2005-01-01

78

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

PubMed Central

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

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

2009-01-01

79

Measuring Intergenerational Obligations  

ERIC Educational Resources Information Center

Researchers have defined intergenerational obligations in diverse ways, and they have used many labels and ways of measuring intergenerational obligations. Using vignettes, we compared responses to questions about what family members should do when another family member needed assistance ("normative obligations") with responses to questions about…

Ganong, Lawrence; Coleman, Marilyn

2005-01-01

80

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

PubMed Central

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

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

2009-01-01

81

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. PMID:25401095

Moore, Elizabeth R.; Ouellette, Scot P.

2014-01-01

82

Complete genome sequence of the Q-fever pathogen Coxiella burnetii  

PubMed Central

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, and detoxification. A previously uncharacterized 13-member family of ankyrin repeat-containing proteins is implicated in the pathogenesis of this organism. Although the lifestyle and parasitic strategies of C. burnetii resemble that of Rickettsiae and Chlamydiae, their genome architectures differ considerably in terms of presence of mobile elements, extent of genome reduction, metabolic capabilities, and transporter profiles. The presence of 83 pseudogenes displays an ongoing process of gene degradation. Unlike other obligate intracellular bacteria, 32 insertion sequences are found dispersed in the chromosome, indicating some plasticity in the C. burnetii genome. These analyses suggest that the obligate intracellular lifestyle of C. burnetii may be a relatively recent innovation. PMID:12704232

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

2003-01-01

83

GRANDPARENTS' ENTITLEMENTS AND OBLIGATIONS  

PubMed Central

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

Draper, Heather

2013-01-01

84

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

85

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

86

ORIGINAL ARTICLE Detection of a novel intracellular microbiome hosted  

E-print Network

ORIGINAL ARTICLE Detection of a novel intracellular microbiome hosted in arbuscular mycorrhizal) are important members of the plant microbiome. They are obligate biotrophs that colonize the roots of most land time that fungi support an intracellular bacterial microbiome, in which distinct types of endobacteria

Bruns, Tom

87

Nitric oxide from IFN?-primed macrophages modulates the antimicrobial activity of ?-lactams against the intracellular pathogens Burkholderia pseudomallei and Nontyphoidal Salmonella.  

PubMed

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; Vázquez-Torres, Andrés

2014-08-01

88

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.; Vázquez-Torres, Andrés

2014-01-01

89

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

PubMed

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

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

2014-01-01

90

Intracellular Locations of Replication Proteins and the Origin of Replication during Chromosome Duplication in the Slowly Growing Human Pathogen Helicobacter pylori  

PubMed Central

We followed the position of the replication complex in the pathogenic bacterium Helicobacter pylori using antibodies raised against the single-stranded DNA binding protein (HpSSB) and the replicative helicase (HpDnaB). The position of the replication origin, oriC, was also localized in growing cells by fluorescence in situ hybridization (FISH) with fluorescence-labeled DNA sequences adjacent to the origin. The replisome assembled at oriC near one of the cell poles, and the two forks moved together toward the cell center as replication progressed in the growing cell. Termination and resolution of the forks occurred near midcell, on one side of the septal membrane. The duplicated copies of oriC did not separate until late in elongation, when the daughter chromosomes segregated into bilobed nucleoids, suggesting sister chromatid cohesion at or near the oriC region. Components of the replication machinery, viz., HpDnaB and HpDnaG (DNA primase), were found associated with the cell membrane. A model for the assembly and location of the H. pylori replication machinery during chromosomal duplication is presented. PMID:24363345

Sharma, Atul; Kamran, Mohammad; Verma, Vijay

2014-01-01

91

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

PubMed

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

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

2014-01-25

92

The combined actions of the copper-responsive repressor CsoR and copper-metallochaperone CopZ modulate CopA-mediated copper efflux in the intracellular pathogen Listeria monocytogenes.  

PubMed

We have characterized the csoR-copA-copZ copper resistance operon of the important human intracellular pathogen Listeria monocytogenes. Transcription of the operon is specifically induced by copper, and mutants lacking the P?-type ATPase CopA have reduced copper tolerance and over-accumulate copper relative to wild type. The copper-responsive repressor CsoR autoregulates transcription by binding to a single 32 bp site spanning the -10 and -35 elements of the promoter. Copper co-ordination by CsoR derepresses transcription of the operon and alters CsoR:DNA complex assembly as determined by DNase I footprinting and electrophoretic mobility shift assays, with some DNA-binding capacity being retained in the presence of 2 mole equivalents of copper. Analysis of the CsoR copper sensory site demonstrated that substitution of Cys?² with Ala generated a CsoR variant that was unresponsive to copper. Importantly, in the absence of CopZ, copper responsiveness of csoR-copA-copZ expression is substantially increased, implying that CopZ reduces the access of CsoR to copper. Furthermore, CopZ is shown to confer copper resistance in mutants lacking copper-inducible csoR-copA-copZ expression, thus providing protection from the deleterious effects of copper within the cytoplasm. PMID:21564342

Corbett, David; Schuler, Stephanie; Glenn, Sarah; Andrew, Peter W; Cavet, Jennifer S; Roberts, Ian S

2011-07-01

93

Comparison of the 'Ca Liberibacter asiaticus' genome adapted for an intracellular lifestyle with other members of the rhizobiales  

Technology Transfer Automated Retrieval System (TEKTRAN)

An intracellular plant pathogen ‘Ca. Liberibacter asiaticus,’ a member of the Rhizobiales, is related to Sinorhizobium meliloti, Bradyrhizobium japonicum, Agrobacterium tumefaciens and Bartonella henselae, an intracellular mammalian pathogen. Whole chromosome comparisons identified at least 52 clust...

94

Visualization of pseudogenes in intracellular bacteria reveals the different tracks to gene destruction  

Microsoft Academic Search

BACKGROUND: Pseudogenes reveal ancestral gene functions. Some obligate intracellular bacteria, such as Mycobacterium leprae and Rickettsia spp., carry substantial fractions of pseudogenes. Until recently, horizontal gene transfers were considered to be rare events in obligate host-associated bacteria. RESULTS: We present a visualization tool that displays the relationships and positions of degraded and partially overlapping gene sequences in multiple genomes. With

Hans-Henrik Fuxelius; Alistair C Darby; Nam-Huyk Cho; Siv GE Andersson

2008-01-01

95

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

PubMed

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

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

2014-09-26

96

Population dynamics of obligate cooperators  

PubMed Central

Obligate cooperative breeding species demonstrate a high rate of group extinction, which may be due to the existence of a critical number of helpers below which the group cannot subsist. Through a simple model, we study the population dynamics of obligate cooperative breeding species, taking into account the existence of a lower threshold below which the instantaneous growth rate becomes negative. The model successively incorporates (i) a distinction between species that need helpers for reproduction, survival or both, (ii) the existence of a migration rate accounting for dispersal, and (iii) stochastic mortality to simulate the effects of random catastrophic events. Our results suggest that the need for a minimum number of helpers increases the risk of extinction for obligate cooperative breeding species. The constraint imposed by this threshold is higher when helpers are needed for reproduction only or for both reproduction and survival. By driving them below this lower threshold, stochastic mortality of lower amplitude and/or lower frequency than for non-cooperative breeders may be sufficient to cause the extinction of obligate cooperative breeding groups. Migration may have a buffering effect only for groups where immigration is higher than emigration; otherwise (when immigrants from nearby groups are not available) it lowers the difference between actual group size and critical threshold, thereby constituting a higher constraint.

Courchamp, F.; Grenfell, B.; Clutton-Brock, T.

1999-01-01

97

38 CFR 17.607 - Obligated service.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

98

38 CFR 17.607 - Obligated service.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

99

38 CFR 17.607 - Obligated service.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

100

38 CFR 17.607 - Obligated service.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

101

17 CFR 200.54 - Constitutional obligations.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Constitutional obligations. 200.54 Section... Canons of Ethics § 200.54 Constitutional obligations. The members...guard against any infringement of the constitutional rights, privileges, or...

2010-04-01

102

5 CFR 724.302 - Reporting obligations.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Reporting obligations. 724... OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL...Report § 724.302 Reporting obligations. ...by April 25, 2007. Future reports must include...Office of Personnel...

2010-01-01

103

Federal Academic Science and Engineering Obligations Decreased  

NSF Publications Database

Federal Academic Science and Engineering Obligations Decreased Slightly in FY 1996 (April 27, 1998 ... findings on academic S&E obligations for Fiscal Year 1996. A full set of Detailed Statistical Tables ...

104

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

PubMed Central

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

Chong, Audrey; Celli, Jean

2010-01-01

105

Rickettsia as obligate and mycetomic bacteria.  

PubMed

Rickettsiae are well known as intracellular pathogens of animals, humans, and plants and facultative and unorganized symbionts of invertebrates. No close relative of mitochondria has yet been associated with nutritional or developmental dependency of its host cell or organism. We have found a mycetomic Rickettsia that is a strict obligatory symbiont of the parthenogenetic booklouse Liposcelis bostrychophila (Psocoptera). These rickettsiae show an evolutionary transition from a solitary to a primary mycetomic bacterium adapted to the development of its host. These intracellular and intranuclear bacteria reside in specialized cells in several tissues. Their distribution changes markedly with the development of their host. The most advanced phenotype is a paired mycetome in the abdomen, described for the first time for Rickettsia and this host order. The mycetomic rickettsiae of two parthenogenetic book lice species are in the spotted fever group and in the basal limoniae group. While mycetomic bacteria are well known for their metabolic or light-emitting functions, these rickettsiae have an essential role in the early development of the oocyte. Removal of the Rickettsia stops egg production and reproduction in the book louse. In two phylogenetically distant psocopteran species, Rickettsia are shown to be associated with four transitional stages from free bacteria, infected cells, through single mycetocytes to organ-forming mycetomes. PMID:17012243

Perotti, M Alejandra; Clarke, Heather K; Turner, Bryan D; Braig, Henk R

2006-11-01

106

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...

107

Genetic Transformation of an Obligate Anaerobe, P. gingivalis for FMN-Green Fluorescent Protein Expression in Studying Host-Microbe Interaction  

PubMed Central

The recent introduction of “oxygen-independent” flavin mononucleotide (FMN)-based fluorescent proteins (FbFPs) is of major interest to both eukaryotic and prokaryotic microbial biologists. Accordingly, we demonstrate for the first time that an obligate anaerobe, the successful opportunistic pathogen of the oral cavity, Porphyromonas gingivalis, can be genetically engineered for expression of the non-toxic green FbFP. The resulting transformants are functional for studying dynamic bacterial processes in living host cells. The visualization of the transformed P. gingivalis (PgFbFP) revealed strong fluorescence that reached a maximum emission at 495 nm as determined by fluorescence microscopy and spectrofluorometry. Human primary gingival epithelial cells (GECs) were infected with PgFbFP and the bacterial invasion of host cells was analyzed by a quantitative fluorescence microscopy and antibiotic protection assays. The results showed similar levels of intracellular bacteria for both wild type and PgFbFP strains. In conjunction with organelle specific fluorescent dyes, utilization of the transformed strain provided direct and accurate determination of the live/metabolically active P. gingivalis' trafficking in the GECs over time. Furthermore, the GECs were co-infected with PgFbFP and the ATP-dependent Clp serine protease-deficient mutant (ClpP-) to study the differential fates of the two strains within the same host cells. Quantitative co-localization analyses displayed the intracellular PgFbFP significantly associated with the endoplasmic reticulum network, whereas the majority of ClpP- organisms trafficked into the lysosomes. Hence, we have developed a novel and reliable method to characterize live host cell-microbe interactions and demonstrated the adaptability of FMN-green fluorescent protein for studying persistent host infections induced by obligate anaerobic organisms. PMID:21525983

Choi, Chul Hee; DeGuzman, Jefferson V.; Lamont, Richard J.; Yilmaz, Özlem

2011-01-01

108

Invasion and Intracellular Survival of Burkholderia cepacia  

PubMed Central

Burkholderia cepacia has emerged as an important pulmonary pathogen in immunocompromised patients and in patients with cystic fibrosis (CF). Little is known about the virulence factors and pathogenesis of B. cepacia, although the persistent and sometimes invasive infections caused by B. cepacia suggest that the organism possesses mechanisms for both cellular invasion and evasion of the host immune response. In this study, cultured human cells were used to analyze the invasion and intracellular survival of B. cepacia J2315, a highly transmissible clinical isolate responsible for morbidity and mortality in CF patients. Quantitative invasion and intracellular growth assays demonstrated that B. cepacia J2315 was able to enter, survive, and replicate intracellularly in U937-derived macrophages and A549 pulmonary epithelial cells. Transmission electron microscopy of infected macrophages confirmed the presence of intracellular B. cepacia and showed that intracellular bacteria were contained within membrane-bound vacuoles. An environmental isolate of B. cepacia, strain J2540, was also examined for its ability to invade and survive intracellularly in cultured human cells. J2540 entered cultured macrophages with an invasion frequency similar to that of the clinical strain, but it was less invasive than the clinical strain in epithelial cells. In marked contrast to the clinical strain, the environmental isolate was unable to survive or replicate intracellularly in either cultured macrophages or epithelial cells. Invasion and intracellular survival may play important roles in the ability of virulent strains of B. cepacia to evade the host immune response and cause persistent infections in CF patients. PMID:10603364

Martin, Daniel W.; Mohr, Christian D.

2000-01-01

109

SNARE Protein Mimicry by an Intracellular Bacterium Cedric Delevoye1  

E-print Network

University Medical Center, New York, New York, United States of America Abstract Many intracellular pathogens to subvert intracellular trafficking are often unknown, and SNARE proteins, which are essential for membrane motifs similar to those found in a bona fide SNARE complex. Moreover, point mutations in the central

Boyer, Edmond

110

Cell biology of the intracellular infection by Legionella pneumophila  

Microsoft Academic Search

Legionella pneumophila has become a paradigm for facultative intracellular pathogens that modulate biogenesis of their phagosomes into replicative niches. The ability to alter host cell biology and tailor it into a hospitable host for intracellular proliferation is at the crux of the mechanism of pathogenesis of Legionnaires’ disease.

Maëlle Molmeret; Dina M. Bitar; Lihui Han; Yousef Abu Kwaik

2004-01-01

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

Collectivizing rescue obligations in bioethics.  

PubMed

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

Garrett, Jeremy R

2015-02-01

113

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

114

38 CFR 17.607 - Obligated service.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

115

Long-Term Survival and Intracellular Replication of Mycoplasma hominis in Trichomonas vaginalis Cells: Potential Role of the Protozoon in Transmitting Bacterial Infection  

PubMed Central

The existence of a symbiotic relationship between Trichomonas vaginalis and Mycoplasma hominis, which is the first reported example of symbiosis between two obligate human pathogens, has been recently reported by our research group. In this work, we examined the cellular location of M. hominis in respect to T. vaginalis. By using gentamicin protection assays, double immunofluorescence, and confocal microscopy, we obtained strong evidence that M. hominis is located within protozoan cells. 5-Bromodeoxyuridine incorporation assays showed that intracellularly located mycoplasmas actively synthesize DNA. Our results demonstrate that M. hominis has the capability of entering trichomonad cells and of replicating inside the protozoon. These findings suggest that symbiosis might provide the bacteria, during human infection, with the capability to resist to environmental stresses, such as host defense mechanisms and pharmacological therapies. PMID:15664961

Dessì, Daniele; Delogu, Giuseppe; Emonte, Eleonora; Catania, Maria Rosaria; Fiori, Pier Luigi; Rappelli, Paola

2005-01-01

116

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

117

The Unappreciated Intracellular Lifestyle of Blastomyces dermatitidis.  

PubMed

Blastomyces dermatitidis, a dimorphic fungus and the causative agent of blastomycosis, is widely considered an extracellular pathogen, with little evidence for a facultative intracellular lifestyle. We infected mice with spores, that is, the infectious particle, via the pulmonary route and studied intracellular residence, transition to pathogenic yeast, and replication inside lung cells. Nearly 80% of spores were inside cells at 24 h postinfection with 10(4) spores. Most spores were located inside of alveolar macrophages, with smaller numbers in neutrophils and dendritic cells. Real-time imaging showed rapid uptake of spores into alveolar macrophages, conversion to yeast, and intracellular multiplication during in vitro coculture. The finding of multiple yeast in a macrophage was chiefly due to intracellular replication rather than multiple phagocytic events or fusion of macrophages. Depletion of alveolar macrophages curtailed infection in mice infected with spores and led to a 26-fold reduction in lung CFU by 6 d postinfection versus nondepleted mice. Phase transition of the spores to yeast was delayed in these depleted mice over a time frame that correlated with reduced lung CFU. Spores cultured in vitro converted to yeast faster in the presence of macrophages than in medium alone. Thus, although advanced B. dermatitidis infection may exhibit extracellular residence in tissue, early lung infection with infectious spores reveals its unappreciated facultative intracellular lifestyle. PMID:25589071

Sterkel, Alana K; Mettelman, Robert; Wüthrich, Marcel; Klein, Bruce S

2015-02-15

118

31 CFR 225.5 - Pledge of definitive Government obligations.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

119

31 CFR 225.5 - Pledge of definitive Government obligations.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

120

31 CFR 225.5 - Pledge of definitive Government obligations.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

121

31 CFR 225.5 - Pledge of definitive Government obligations.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

122

31 CFR 225.5 - Pledge of definitive Government obligations.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

123

49 CFR 22.17 - Compliance with child support obligations.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Compliance with child support obligations. 22.17 Section... § 22.17 Compliance with child support obligations. Any holder...delinquent on any obligation to pay child support arising under: (a) An...

2010-10-01

124

28 CFR 811.3 - Notice of obligation to register.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Notice of obligation to register. 811.3 Section 811.3 Judicial...811.3 Notice of obligation to register. (a) Sex offenders may be notified of their obligation to register under various provisions...

2010-07-01

125

18 CFR 292.311 - Reinstatement of obligation to purchase.  

Code of Federal Regulations, 2010 CFR

...Reinstatement of obligation to purchase. 292.311 Section 292...Reinstatement of obligation to purchase. At any time after the Commission makes a...utility of its obligation to purchase electric energy, a...

2010-04-01

126

18 CFR 292.311 - Reinstatement of obligation to purchase.  

Code of Federal Regulations, 2013 CFR

...Reinstatement of obligation to purchase. 292.311 Section 292...Reinstatement of obligation to purchase. At any time after the Commission makes a...utility of its obligation to purchase electric energy, a...

2013-04-01

127

18 CFR 292.311 - Reinstatement of obligation to purchase.  

Code of Federal Regulations, 2012 CFR

...Reinstatement of obligation to purchase. 292.311 Section 292...Reinstatement of obligation to purchase. At any time after the Commission makes a...utility of its obligation to purchase electric energy, a...

2012-04-01

128

18 CFR 292.311 - Reinstatement of obligation to purchase.  

Code of Federal Regulations, 2011 CFR

...Reinstatement of obligation to purchase. 292.311 Section 292...Reinstatement of obligation to purchase. At any time after the Commission makes a...utility of its obligation to purchase electric energy, a...

2011-04-01

129

18 CFR 292.311 - Reinstatement of obligation to purchase.  

Code of Federal Regulations, 2014 CFR

...Reinstatement of obligation to purchase. 292.311 Section 292...Reinstatement of obligation to purchase. At any time after the Commission makes a...utility of its obligation to purchase electric energy, a...

2014-04-01

130

Host metabolism regulates intracellular growth of Trypanosoma cruzi  

PubMed Central

SUMMARY 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.

2012-01-01

131

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2011 CFR

...Teaching obligation. Upon receiving a Master's degree, each Fellow must teach American history, American government, social studies, or political science on a full-time basis to students in secondary school for a period of not less than one...

2011-10-01

132

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2010 CFR

...Teaching obligation. Upon receiving a Master's degree, each Fellow must teach American history, American government, social studies, or political science on a full-time basis to students in secondary school for a period of not less than one...

2010-10-01

133

19 CFR 10.412 - Importer obligations.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

134

19 CFR 10.412 - 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-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

2011-04-01

135

19 CFR 10.412 - 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-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

2013-04-01

136

19 CFR 10.412 - 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-Chile Free Trade Agreement Import Requirements § 10.412 Importer obligations. (a) General. An importer...

2012-04-01

137

19 CFR 10.412 - Importer obligations.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

138

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

139

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

140

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

141

19 CFR 10.865 - Importer obligations.  

Code of Federal Regulations, 2014 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...

2014-04-01

142

38 CFR 17.632 - Obligated service.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

143

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

144

46 CFR Sec. 11 - Guarantee obligations.  

Code of Federal Regulations, 2010 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...

2010-10-01

145

46 CFR Sec. 11 - Guarantee obligations.  

Code of Federal Regulations, 2011 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...

2011-10-01

146

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

147

46 CFR Sec. 11 - Guarantee obligations.  

Code of Federal Regulations, 2012 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...

2012-10-01

148

46 CFR Sec. 11 - Guarantee obligations.  

Code of Federal Regulations, 2014 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...

2014-10-01

149

19 CFR 10.705 - Importer obligations.  

Code of Federal Regulations, 2010 CFR

...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Import Requirements § 10.705 Importer obligations. (a) General. An importer who...

2010-04-01

150

19 CFR 10.705 - 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-Jordan Free Trade Agreement Import Requirements § 10.705 Importer obligations. (a) General. An importer who...

2013-04-01

151

19 CFR 10.705 - 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-Jordan Free Trade Agreement Import Requirements § 10.705 Importer obligations. (a) General. An importer who...

2011-04-01

152

19 CFR 10.705 - Importer obligations.  

Code of Federal Regulations, 2014 CFR

...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. United States-Jordan Free Trade Agreement Import Requirements § 10.705 Importer obligations. (a) General. An importer who...

2014-04-01

153

19 CFR 10.705 - 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-Jordan Free Trade Agreement Import Requirements § 10.705 Importer obligations. (a) General. An importer who...

2012-04-01

154

Subversion of the cytoskeleton by intracellular bacteria: lessons from Listeria, Salmonella and Vibrio.  

PubMed

Entry into host cells and intracellular persistence by invasive bacteria are tightly coupled to the ability of the bacterium to disrupt the eukaryotic cytoskeletal machinery. Herein we review the main strategies used by three intracellular pathogens to harness key modulators of the cytoskeleton. Two of these bacteria, namely Listeria monocytogenes and Salmonella enterica serovar Typhimurium, exhibit quite distinct intracellular lifestyles and therefore provide a comprehensive panel for the understanding of the intricate bacteria-cytoskeleton interplay during infections. The emerging intracellular pathogen Vibrio parahaemolyticus is depicted as a developing model for the uncovering of novel mechanisms used to hijack the cytoskeleton. PMID:25440316

de Souza Santos, Marcela; Orth, Kim

2015-02-01

155

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

156

Host-Apicomplexan Parasite Interactions: Leveraging Biological Discovery Into Antiparasitic Drug Development.  

E-print Network

??The obligate intracellular pathogens Plasmodium falciparum and Toxoplasma gondii remodel their host cell to facilitate their intracellular development and progress through their asexual life cycle,… (more)

Millholland, Melanie Grace

2013-01-01

157

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

158

Professional obligations, employment responsibilities and collective bargaining  

Microsoft Academic Search

Labour relations scholars have been discussing the proper relationship between professional obligations and collective bargaining at least since Shirley Goldenberg's study for the 1968 Task Force on Industrial Relations. The positions taken have ranged from rabid assertions that professionalism can flower only in a rarefied atmosphere graced with a pupil\\/teacher ratio lower than 12:1 to a recent solemn declaration by

Kenneth P. Swan

1978-01-01

159

The author’s opportunity and obligation  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

160

Classroom Curriculum: Balancing Autonomy and Obligation.  

ERIC Educational Resources Information Center

This study investigated the influences shaping the curriculum decision-making process of four English teachers in two middle schools in order to identify sources of professional autonomy and obligation in classroom curriculum. These teachers made decisions daily by selecting content, texts and materials, modes of presentation, learning activities,…

Hawthorne, Rebecca Killen

161

Chloride Channels of Intracellular Membranes  

PubMed Central

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

Edwards, John C.; Kahl, Christina R.

2010-01-01

162

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

2008-01-01

163

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

PubMed Central

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

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

2009-01-01

164

47 CFR 80.105 - General obligations of coast stations.  

Code of Federal Regulations, 2010 CFR

... false General obligations of coast stations. 80.105 Section 80.105 Telecommunication... SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Operating...Procedures Operating Procedures-Land Stations § 80.105 General obligations...

2010-10-01

165

7 CFR 4274.355 - Loan approval and obligating funds.  

Code of Federal Regulations, 2010 CFR

...false Loan approval and obligating funds. 4274.355 Section 4274.355 Agriculture Regulations of the Department of Agriculture... Intermediary Relending Program (IRP) § 4274.355 Loan approval and obligating funds. The...

2010-01-01

166

47 CFR 24.247 - Triggering a reimbursement obligation.  

Code of Federal Regulations, 2010 CFR

...false Triggering a reimbursement obligation. 24.247 Section 24.247 Telecommunication FEDERAL COMMUNICATIONS COMMISSION...Microwave Relocation from the 1850-1990 Mhz Band § 24.247 Triggering a reimbursement obligation. (a)...

2010-10-01

167

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2010 CFR

...listing of obligated projects. 450.332 ...TRANSPORTATION PLANNING AND RESEARCH PLANNING...Metropolitan Transportation Planning and Programming...listing of obligated projects. (a) In metropolitan planning areas, on...

2010-04-01

168

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2011 CFR

...listing of obligated projects. 450.332 ...TRANSPORTATION PLANNING AND RESEARCH PLANNING...Metropolitan Transportation Planning and Programming...listing of obligated projects. (a) In metropolitan planning areas, on...

2011-04-01

169

47 CFR 90.673 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2011 CFR

... Obligation to abate unacceptable interference. 90.673 Section 90.673 Telecommunication...Procedures and Process-Unacceptable Interference § 90.673 Obligation to abate unacceptable interference. (a) Strict...

2011-10-01

170

47 CFR 22.971 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2014 CFR

... Obligation to abate unacceptable interference. 22.971 Section 22.971 Telecommunication... Obligation to abate unacceptable interference. (a) Strict Responsibility...contributes to causing unacceptable interference to a non-cellular part 90 of...

2014-10-01

171

47 CFR 22.971 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2013 CFR

... Obligation to abate unacceptable interference. 22.971 Section 22.971 Telecommunication... Obligation to abate unacceptable interference. (a) Strict Responsibility...contributes to causing unacceptable interference to a non-cellular part 90 of...

2013-10-01

172

47 CFR 22.971 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2012 CFR

... Obligation to abate unacceptable interference. 22.971 Section 22.971 Telecommunication... Obligation to abate unacceptable interference. (a) Strict Responsibility...contributes to causing unacceptable interference to a non-cellular part 90 of...

2012-10-01

173

47 CFR 22.878 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2013 CFR

... Obligation to abate unacceptable interference. 22.878 Section 22.878 Telecommunication... Obligation to abate unacceptable interference. This section applies only...contributes to causing unacceptable interference to a non-cellular part 90...

2013-10-01

174

47 CFR 90.673 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2013 CFR

... Obligation to abate unacceptable interference. 90.673 Section 90.673 Telecommunication...Procedures and Process-Unacceptable Interference § 90.673 Obligation to abate unacceptable interference. (a) Strict...

2013-10-01

175

47 CFR 22.878 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2012 CFR

... Obligation to abate unacceptable interference. 22.878 Section 22.878 Telecommunication... Obligation to abate unacceptable interference. This section applies only...contributes to causing unacceptable interference to a non-cellular part 90...

2012-10-01

176

47 CFR 22.878 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2011 CFR

... Obligation to abate unacceptable interference. 22.878 Section 22.878 Telecommunication... Obligation to abate unacceptable interference. This section applies only...contributes to causing unacceptable interference to a non-cellular part 90...

2011-10-01

177

47 CFR 22.878 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2010 CFR

... Obligation to abate unacceptable interference. 22.878 Section 22.878 Telecommunication... Obligation to abate unacceptable interference. This section applies only...contributes to causing unacceptable interference to a non-cellular part 90...

2010-10-01

178

47 CFR 90.673 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2010 CFR

... Obligation to abate unacceptable interference. 90.673 Section 90.673 Telecommunication...Procedures and Process-Unacceptable Interference § 90.673 Obligation to abate unacceptable interference. (a) Strict...

2010-10-01

179

47 CFR 22.878 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2014 CFR

... Obligation to abate unacceptable interference. 22.878 Section 22.878 Telecommunication... Obligation to abate unacceptable interference. This section applies only...contributes to causing unacceptable interference to a non-cellular part 90...

2014-10-01

180

47 CFR 90.673 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2012 CFR

... Obligation to abate unacceptable interference. 90.673 Section 90.673 Telecommunication...Procedures and Process-Unacceptable Interference § 90.673 Obligation to abate unacceptable interference. (a) Strict...

2012-10-01

181

47 CFR 22.971 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2010 CFR

... Obligation to abate unacceptable interference. 22.971 Section 22.971 Telecommunication... Obligation to abate unacceptable interference. (a) Strict Responsibility...contributes to causing unacceptable interference to a non-cellular part 90 of...

2010-10-01

182

47 CFR 22.971 - Obligation to abate unacceptable interference.  

Code of Federal Regulations, 2011 CFR

... Obligation to abate unacceptable interference. 22.971 Section 22.971 Telecommunication... Obligation to abate unacceptable interference. (a) Strict Responsibility...contributes to causing unacceptable interference to a non-cellular part 90 of...

2011-10-01

183

22 CFR 221.15 - Fiscal Agent obligations.  

Code of Federal Regulations, 2011 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations pursuant...Guarantee, but may be the subject of action for damages...

2011-04-01

184

22 CFR 221.15 - Fiscal Agent obligations.  

Code of Federal Regulations, 2013 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations pursuant...Guarantee, but may be the subject of action for damages...

2013-04-01

185

22 CFR 230.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2014 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER...SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations...

2014-04-01

186

22 CFR 221.15 - Fiscal Agent obligations.  

Code of Federal Regulations, 2010 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations pursuant...Guarantee, but may be the subject of action for damages...

2010-04-01

187

22 CFR 230.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2010 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER...SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations...

2010-04-01

188

22 CFR 221.15 - Fiscal Agent obligations.  

Code of Federal Regulations, 2014 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations pursuant...Guarantee, but may be the subject of action for damages...

2014-04-01

189

22 CFR 230.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2013 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER...SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations...

2013-04-01

190

22 CFR 230.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2011 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER...SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations...

2011-04-01

191

22 CFR 221.15 - Fiscal Agent obligations.  

Code of Federal Regulations, 2012 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEE STANDARD TERMS...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations pursuant...Guarantee, but may be the subject of action for damages...

2012-04-01

192

22 CFR 230.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2012 CFR

... AGENCY FOR INTERNATIONAL DEVELOPMENT ISRAEL LOAN GUARANTEES ISSUED UNDER...SUPPLEMENTAL APPROPRIATIONS ACT OF 2003, PUB. L. 108-11-STANDARD...Agent obligations. Failure of the Fiscal Agent to perform any of its obligations...

2012-04-01

193

Label-free imaging and spectroscopic analysis of intracellular bacterial infections.  

PubMed

Staphylococcus aureus is one of the most frequent human pathogens that can also act as a facultative intracellular pathogen causing infections that are extremely difficult to treat. Only little is known about the pathogen's intracellular adaptation strategies to escape the host's response. Here, we present an advanced Raman-based imaging approach providing high quality false-color images to specifically identify intracellular S. aureus and to localize them exactly in three dimensions within endothelial cells. At the same time unprecedented insights into the metabolic characteristics of the pathogen are provided in a label-free and nondestructive manner. The spectral information reveals that the intracellular bacteria are in the exponential growth phase with a reduced replication rate and biochemically different from extracellular bacteria proving their adaptation to the host's conditions. This powerful biophotonic analysis tool paves the way for further mechanistic studies of difficult-to-investigate infection processes. PMID:25582952

Große, Christina; Bergner, Norbert; Dellith, Jan; Heller, Regine; Bauer, Michael; Mellmann, Alexander; Popp, Jürgen; Neugebauer, Ute

2015-02-17

194

Intracellular Demography and the Dynamics of Salmonella enterica Infections  

Microsoft Academic Search

An understanding of within-host dynamics of pathogen interactions with eukaryotic cells can shape the development of effective preventive measures and drug regimes. Such investigations have been hampered by the difficulty of identifying and observing directly, within live tissues, the multiple key variables that underlay infection processes. Fluorescence microscopy data on intracellular distributions of Salmonella enterica serovar Typhimurium (S. Typhimurium) show

Sam P Brown; Stephen J Cornell; Mark Sheppard; Andrew J Grant; Duncan J Maskell; Bryan T Grenfell; Pietro Mastroeni

2006-01-01

195

Unveiling the Intracellular Survival Gene Kit of Trypanosomatid Parasites  

PubMed Central

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

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

2014-01-01

196

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

197

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

198

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

199

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

200

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

201

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

Microsoft Academic Search

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

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

2011-01-01

202

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

203

1 Lipopolysaccharide Neutralizing Peptide-Porphyrin Conjugates for 2 Effective Photoinactivation and Intracellular Imaging of Gram-  

E-print Network

and Intracellular Imaging of Gram- 3 Negative Bacteria Strains 4 Fang Liu, Annie Soh Yan Ni, Yingjie Lim, Harini tion of Gram-negative bacterial strains. The intracellular 14 fluorescent imaging and photodynamic activities against Gram-negative bacterial pathogens especially 19 for those with antibiotics resistance when

Xing, Bengang

204

Informed consent: Enforcing pharmaceutical companies' obligations abroad.  

PubMed

The past several years have seen an evolution in the obligations of pharmaceutical companies conducting clinical trials abroad. Key players, such as international human rights organizations, multinational pharmaceutical companies, the United States government and courts, and the media, have played a significant role in defining these obligations. This article examines how such obligations have developed through the lens of past, present, and future recommendations for informed consent protections. In doing so, this article suggests that, no matter how robust obligations appear, they will continue to fall short of providing meaningful protection until they are accompanied by a substantive enforcement mechanism that holds multinational pharmaceutical companies accountable for their conduct. Issues of national sovereignty, particularly in the United States, will continue to prevent meaningful enforcement by an international tribunal or through one universally adopted code of ethics. This article argues that, rather than continuing to pursue an untenable international approach, the Alien Torts Statute (ATS) offers a viable enforcement mechanism, at least for US-based pharmaceutical companies. Recent federal appellate court precedent interpreting the ATS provides the mechanism for granting victims redress and enforcing accountability of sponsors (usually pharmaceutical companies and research and academic institutions) for informed consent misconduct. Substantive human rights protections are vital in order to ensure that every person can realize the "right to health." This article concludes that by building on the federal appellate court's ATS analysis, which grants foreign trial participants the right to pursue claims of human rights violations in US courts, a mechanism can be created for enforcing not only substantive informed consent, but also human rights protections. PMID:20930251

Lee, Stacey B

2010-01-01

205

Drosophila eiger Mutants Are Sensitive to Extracellular Pathogens  

PubMed Central

We showed previously that eiger, the Drosophila tumor necrosis factor homolog, contributes to the pathology induced by infection with Salmonella typhimurium. We were curious whether eiger is always detrimental in the context of infection or if it plays a role in fighting some types of microbes. We challenged wild-type and eiger mutant flies with a collection of facultative intracellular and extracellular pathogens, including a fungus and Gram-positive and Gram-negative bacteria. The response of eiger mutants divided these microbes into two groups: eiger mutants are immunocompromised with respect to extracellular pathogens but show no change or reduced sensitivity to facultative intracellular pathogens. Hence, eiger helps fight infections but also can cause pathology. We propose that eiger activates the cellular immune response of the fly to aid clearance of extracellular pathogens. Intracellular pathogens, which can already defeat professional phagocytes, are unaffected by eiger. PMID:17381241

Schneider, David S; Ayres, Janelle S; Brandt, Stephanie M; Costa, Alexandre; Dionne, Marc S; Gordon, Michael D; Mabery, Eric M; Moule, Madeleine G; Pham, Linh N; Shirasu-Hiza, Mimi M

2007-01-01

206

Drosophila eiger mutants are sensitive to extracellular pathogens.  

PubMed

We showed previously that eiger, the Drosophila tumor necrosis factor homolog, contributes to the pathology induced by infection with Salmonella typhimurium. We were curious whether eiger is always detrimental in the context of infection or if it plays a role in fighting some types of microbes. We challenged wild-type and eiger mutant flies with a collection of facultative intracellular and extracellular pathogens, including a fungus and Gram-positive and Gram-negative bacteria. The response of eiger mutants divided these microbes into two groups: eiger mutants are immunocompromised with respect to extracellular pathogens but show no change or reduced sensitivity to facultative intracellular pathogens. Hence, eiger helps fight infections but also can cause pathology. We propose that eiger activates the cellular immune response of the fly to aid clearance of extracellular pathogens. Intracellular pathogens, which can already defeat professional phagocytes, are unaffected by eiger. PMID:17381241

Schneider, David S; Ayres, Janelle S; Brandt, Stephanie M; Costa, Alexandre; Dionne, Marc S; Gordon, Michael D; Mabery, Eric M; Moule, Madeleine G; Pham, Linh N; Shirasu-Hiza, Mimi M

2007-03-01

207

Proteomics of Plant Pathogenic Fungi  

PubMed Central

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

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

2010-01-01

208

The intracellular bacteria Chlamydia hijack peroxisomes and utilize their enzymatic capacity to produce bacteria-specific phospholipids.  

PubMed

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

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

2014-01-01

209

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

210

Pathogen intelligence  

PubMed Central

Different species inhabit different sensory worlds and thus have evolved diverse means of processing information, learning and memory. In the escalated arms race with host defense, each pathogenic bacterium not only has evolved its individual cellular sensing and behavior, but also collective sensing, interbacterial communication, distributed information processing, joint decision making, dissociative behavior, and the phenotypic and genotypic heterogeneity necessary for epidemiologic success. Moreover, pathogenic populations take advantage of dormancy strategies and rapid evolutionary speed, which allow them to save co-generated intelligent traits in a collective genomic memory. This review discusses how these mechanisms add further levels of complexity to bacterial pathogenicity and transmission, and how mining for these mechanisms could help to develop new anti-infective strategies. PMID:24551600

Steinert, Michael

2014-01-01

211

A New Role of the Complement System: C3 Provides Protection in a Mouse Model of Lung Infection with Intracellular Chlamydia psittaci  

PubMed Central

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

212

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

213

Fungal Pathogens: Survival and Replication within Macrophages.  

PubMed

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

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

2014-11-10

214

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

215

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, Sébastien; Trofimov, Valentin; Berschl, Kathrin; Ouertatani-Sakouhi, Hajer; Ackermann, Nikolaus; Hedberg, Christian; Cosson, Pierre; Soldati, Thierry; Hilbi, Hubert

2013-01-01

216

Exploring anti-bacterial compounds against intracellular Legionella.  

PubMed

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, Sébastien; Trofimov, Valentin; Berschl, Kathrin; Ouertatani-Sakouhi, Hajer; Ackermann, Nikolaus; Hedberg, Christian; Cosson, Pierre; Soldati, Thierry; Hilbi, Hubert

2013-01-01

217

Obligately barophilic bacterium from the Mariana trench.  

PubMed Central

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

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

1981-01-01

218

Verifying nonproliferation treaties: Obligation, process, and sovereignty  

SciTech Connect

The foregoing chapters examine what verification is and why states would bother with so difficult and politically sensitive an issue when negotiating agreements on arms control and disarmament issues. Now it is necessary to confront the question of whether there are any meaningful conclusions to be drawn from this exercise. Are the patterns discerned in the history of these treaties meaningful for understanding how other treaties have evolved or will evolve. Are there lessons here which might benefit future negotiators. This final chapter seeks to provide some answers, albeit partial ones, to these questions. There are in fact several interesting and potentially important conclusions to be drawn. Verification of multilateral treaty obligations contains its own intrinsic structure and logic, independent of the obligations undertaken by the parties and the political context in which those undertakings are negotiated and made. The many significant similarities in the verification processes for the CFE Treaty, the NPT, and the CWC demonstrate the degree to which there is such an underlying structure regardless of whether the behavior or activity is strictly military or has essentially civilian dimensions, whether all relevant states participate or only some of the most important states agree from the beginning to participate, and whether the agreement is global or regional in scope.

Kessler, J.C.

1995-10-01

219

Experimental evolution of nodule intracellular infection in legume symbionts.  

PubMed

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, Stéphane; Pouzet, Cécile; Tasse, Lena; Leru, Aurélie; Maillard, Aline; Médigue, Claudine; Batut, Jacques; Masson-Boivin, Catherine; Capela, Delphine

2013-07-01

220

23 CFR 230.205 - Supportive services funds obligation.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

221

[Using of antibodies against Microsporia Hsp70 family proteins for analysis of secretome of intracellular parasites].  

PubMed

Microsporidia is a large group of fungi-related unicellular parasites with obligate intracellular lifestyle. Unlike other protozoan intracellular parasites (Kinetoplastida and Apicomplexa), most microsporidian species develop in direct contact with the host cell cytoplasm. This fact, acquisition of unique transporters to exploit host metabolic system (alongside the strong minimization of own machinery) and predicted repertoire of microsporidia secretome altogether suggest an active role of parasite proteins in the control of infected cell. Lack of information about secretome of microsporidia intracellular stages is largely due to the methodological difficulties of working with the obligate intracellular parasites. An important problem of such study is the contamination of preparations of host cell cytoplasm by inner (nonsecreted) parasite proteins. Even the homogenization of infected tissue in mild conditions and removal of parasite cells by low-speed centrifugation may result in their partial disruption. We expressed the fragments of three Hsp70 family chaperones from the microsporidium Paranosema (Antonospora) locustae in bacteria Escherichia coli. Immunoblotting with proteins of microsporidia intracellular stages and infected host tissue (locust fat bodies) demonstrated that antibodies against recombinant polypeptides may be used to monitor the integrity of parasite cells during homogenization of infected host tissue and subsequent removal of parasites by centrifugation. PMID:23458023

Dolgikh, V V; Senderski?, I V; Pavlova, O A; Timofeev, S A; Naumov, A M

2012-01-01

222

Intracellular sensing of complement C3 activates cell autonomous immunity.  

PubMed

Pathogens traverse multiple barriers during infection, including cell membranes. We found that during this transition, pathogens carried covalently attached complement C3 into the cell, triggering immediate signaling and effector responses. Sensing of C3 in the cytosol activated mitochondrial antiviral signaling (MAVS)-dependent signaling cascades and induced proinflammatory cytokine secretion. C3 also flagged viruses for rapid proteasomal degradation, preventing their replication. This system could detect both viral and bacterial pathogens but was antagonized by enteroviruses, such as rhinovirus and poliovirus, which cleave C3 using their 3C protease. The antiviral rupintrivir inhibited 3C protease and prevented C3 cleavage, rendering enteroviruses susceptible to intracellular complement sensing. Thus, complement C3 allows cells to detect and disable pathogens that have invaded the cytosol. PMID:25190799

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

2014-09-01

223

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

E-print Network

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

Bell, John Alexander

2014-06-28

224

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

225

Intracellular starch formation in corynebacteria.  

PubMed

Carrier, E. Bernard (Louisiana State University, Baton Rouge, La.) and C. S. McCleskey. Intracellular starch formation in cor-yne bacteria. J. Bacteriol. 83:1029-1036. 1962.-Cor-ynebacterium tritici, C. striatum, C. renale, and C. pseudodiphtheriticum produce an intracellular starch-like material when grown on native starches; glucose-1-phosphate, mono-, di-, and trisaccharides do not serve as substrates for intracellular starch formation. C. pseudotuberculosis and C. kutscheri produce intracellular starch from starch substrates and glucose-1-phosphate. C. diphtheriae produces starch from glucose-1-phosphate only. PMID:13876866

CARRIER, E B; McCLESKEY, C S

1962-05-01

226

INTRACELLULAR STARCH FORMATION IN CORYNEBACTERIA  

PubMed Central

Carrier, E. Bernard (Louisiana State University, Baton Rouge, La.) and C. S. McCleskey. Intracellular starch formation in cor-yne bacteria. J. Bacteriol. 83:1029–1036. 1962.—Cor-ynebacterium tritici, C. striatum, C. renale, and C. pseudodiphtheriticum produce an intracellular starch-like material when grown on native starches; glucose-1-phosphate, mono-, di-, and trisaccharides do not serve as substrates for intracellular starch formation. C. pseudotuberculosis and C. kutscheri produce intracellular starch from starch substrates and glucose-1-phosphate. C. diphtheriae produces starch from glucose-1-phosphate only. Images PMID:13876866

Carrier, E. Bernard; McCleskey, C. S.

1962-01-01

227

Eosinophil intracellular signalling: apoptosis.  

PubMed

Eosinophil apoptosis is considered critical for the resolution of eosinophilic inflammation in the airways of asthmatics. Apoptosis can be mediated by an extrinsic receptor-activated pathway or alternatively by an intrinsic pathway via distortion of mitochondrial function. Both of these pathways lead to activation of the caspase cascade resulting in degradation of cellular components. We describe here two methods to explore intracellular mechanisms mediating eosinophil apoptosis. Eosinophil staining by fluorescent probe JC-1 followed by flow cytometric analysis is a reliable method for determination of the state of mitochondrial membrane potential (??m). Lost ??m indicates distorted mitochondrial function and apoptosis. We also describe a method to explore the activation of effector caspase-6 by assessing degradation of its substrate lamin A/C by immunoblotting. PMID:24986608

Ilmarinen, Pinja; Moilanen, Eeva; Kankaanranta, Hannu

2014-01-01

228

12 CFR 997.5 - Termination of the obligation.  

Code of Federal Regulations, 2010 CFR

...Treasury if the term of that obligation extends beyond April 15, 2030, will terminate when the aggregate actual quarterly payments...first obligation of the REFCORP was issued and ends on April 15, 2030. (b) Date of the final payment. The aggregate...

2010-01-01

229

7 CFR 1488.12 - Coverage of bank obligations.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

230

7 CFR 1488.12 - Coverage of bank obligations.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

231

7 CFR 1488.12 - Coverage of bank obligations.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

232

The Hidden Effect of Rules: Behavioural consequences of Obligations  

Microsoft Academic Search

How formal institutions (e.g. laws and public policies) affect human behaviour represents a crucial issue in economic analysis. Formal rules are defined as obligations backed by incentives. The economic literature has largely studied the role of material incentives in shaping individual behaviour. Yet, the role of obligations, i.e. what formal rules ask people to do or not to do, remains

Roberto Galbiati; Pietro Vertova

2006-01-01

233

Child Support Obligations and Low-Income Fathers  

ERIC Educational Resources Information Center

Using the 1994-1998 waves of the Current Population Survey--Child Support Supplement (N = 5,387), the aims of this study are to document child support obligation rates of nonresident fathers, to examine the effect of the obligation rate on child support compliance, and to calculate the trade-off between fathers' financial responsibility and…

Huang, Chien-Chung; Mincy, Ronald B.; Garfinkel, Irwin

2005-01-01

234

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

235

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

236

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

237

Opportunism and competition in the non-fossil fuel obligation  

E-print Network

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

Watson, Andrew

238

Real-time PCR and spore trap-based detection of the downy mildew pathogen, Peronospora effusa  

Technology Transfer Automated Retrieval System (TEKTRAN)

Peronospora effusa is an obligate pathogen and the causal agent of downy mildew on spinach. The pathogen can be dispersed by splashing rain and wind, and may overwinter as oospores. Outbreaks of downy mildew on spinach are common in the cool climate of central coastal California, including the Sal...

239

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

240

A common heritable factor influences prosocial obligations across multiple domains  

PubMed Central

Although it has been shown that prosocial behaviour is heritable, it has not yet been established whether narrower aspects of prosociality are heritable, nor whether a common mechanism influences prosociality across its multiple domains. Here, we examine civic duty, work-place commitment and concern for the welfare of others with a study of prosocial obligations in 958 adult twin-pairs. Multivariate modelling indicated the existence of genetic factors underlying general prosocial obligations in females, with familial effects (genetic and shared-environment effects were indistinguishable) influencing this general mechanism in males. At the domain-specific level, modest genetic effects were observed in females for civic and work obligations, with shared-environment effects influencing welfare obligations. In males, genetic influences were observed for welfare obligation, with unique environments affecting work and civic duty. PMID:21307044

Lewis, Gary J.; Bates, Timothy C.

2011-01-01

241

Adaptive value of polymorphism in intracellular self/not-self discrimination?  

PubMed

A microbial pathogen species can adapt to its host species to the extent that members of the host species are uniform. Loss of this uniformity would make it difficult for a pathogen species to transfer, from one member of the host species to another, what it had "learned" through selection of its members with advantageous mutations. The existence of major histocompatibility complex (MHC) polymorphism indicates that non-uniformity within a species is an effective host defence strategy. By virtue of this molecular discontinuity among its members the host species can "present a moving target" to the pathogen. Many proteins other than MHC proteins show polymorphism - a phenomenon which has suggested that mutations in regions of protein molecules which do not affect overt function are neutral. However, in the context of the author's differential aggregation theory of intracellular self/not-self discrimination as previously applied to the problem of the antigenicity of cancer cells, such polymorphism should serve for the recruitment of subsets of self-antigens into the antigenic repertoire of an infected cell. These would act as "intracellular antibodies" by virtue of their weak, but specific, aggregation with pathogen proteins. Peptides from the self-antigens, as well as (or instead of) those from the antigens of the pathogen, would then serve as targets for attack by cytotoxic T cells. Thus, polymorphism of intracellular proteins should be of adaptive value, serving to amplify and individualize the immune response to intracellular pathogens. PMID:11403563

Forsdyke, D R

2001-06-21

242

Live cell imaging of intracellular Salmonella enterica.  

PubMed

During the intracellular phase of the pathogenic lifestyle, Salmonella enterica massively alters the endosomal system of its host cells. Two hallmarks are the remodeling of phagosomes into the Salmonella-containing vacuole (SCV) as a replicative niche, and the formation of tubular structures, such as Salmonella-induced filaments (SIFs). To study the dynamics and the fate of these Salmonella-specific compartments, live cell imaging (LCI) is a method of choice. In this chapter, we compare currently used microscopy techniques and focus on considerations and requirements specific for LCI. Detailed protocols for LCI of Salmonella infection with either confocal laser scanning microscopy (CLSM) or spinning disk confocal microscopy (SDCM) are provided. PMID:25253257

Kehl, Alexander; Hensel, Michael

2015-01-01

243

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

244

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

245

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

246

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

Code of Federal Regulations, 2014 CFR

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

2014-10-01

247

31 CFR 225.9 - Return of Government obligations to obligor.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

248

31 CFR 225.9 - Return of Government obligations to obligor.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

249

31 CFR 225.9 - Return of Government obligations to obligor.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

250

31 CFR 225.9 - Return of Government obligations to obligor.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

251

31 CFR 225.9 - Return of Government obligations to obligor.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

252

20 CFR 243.2 - Legal process for the enforcement of child support and alimony obligations.  

Code of Federal Regulations, 2010 CFR

...process for the enforcement of child support and alimony obligations. 243...process for the enforcement of child support and alimony obligations. ...of legal obligations to provide child support or to make alimony payments,...

2010-04-01

253

28 CFR 811.5 - Commencement of the obligation to register.  

Code of Federal Regulations, 2010 CFR

...false Commencement of the obligation to register. 811.5 Section 811.5 Judicial...5 Commencement of the obligation to register. (a) A sex offender's obligation to register starts when the sex offender is...

2010-07-01

254

47 CFR 1.21004 - Winning bidder's obligation to apply for support  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Winning bidder's obligation to apply for support ...Service Support § 1.21004 Winning bidder's obligation to apply for support ...and Sufficient Application. A winning bidder has a binding obligation to apply...

2013-10-01

255

47 CFR 1.21004 - Winning bidder's obligation to apply for support  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Winning bidder's obligation to apply for support ...Service Support § 1.21004 Winning bidder's obligation to apply for support ...and Sufficient Application. A winning bidder has a binding obligation to apply...

2012-10-01

256

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

2014-01-01

257

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

258

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

259

Autophagic control of Listeria through intracellular innate immune recognition in drosophila  

PubMed Central

Autophagy, an evolutionally conserved homeostatic process for catabolizing cytoplasmic components, has been implicated in the elimination of intracellular pathogens during mammalian innate immune responses. However, the mechanisms underlying cytoplasmic infection-induced autophagy, and the role of autophagy in host survival against intracellular pathogens are unknown. Here we report that in drosophila, recognition of diaminopimelic acid-type peptidoglycans by the pattern recognition receptor PGRP-LE is crucial for the induction of autophagy, and that autophagy prevents the intracellular growth of Listeria monocytogenes and promotes host survival against this infection. Autophagy induction occurs independently of the Toll and IMD innate signaling pathways. These findings define a clear pathway leading from the intracellular pattern recognition receptors to the induction of autophagy to host defense. PMID:18604211

Yano, Tamaki; Mita, Shizuka; Ohmori, Hiroko; Oshima, Yoshiteru; Fujimoto, Yukari; Ueda, Ryu; Takada, Haruhiko; Goldman, William E.; Fukase, Koichi; Silverman, Neal; Yoshimori, Tamotsu; Kurata, Shoichiro

2008-01-01

260

Role of extracellular nucleotides in the immune response against intracellular bacteria and protozoan parasites  

PubMed Central

Extracellular nucleotides are danger signals involved in recognition and control of intracellular pathogens. They are an important component of the innate immune response against intracellular pathogens, inducing the recruitment of inflammatory cells, stimulating secretion of cytokines, and producing inflammatory mediators such as reactive oxygen species (ROS) and nitric oxide (NO). In the case of extracellular ATP, some of the immune responses are mediated through activation of the NLRP3 inflammasome and secretion of the cytokine, interleukin-1? (IL-1?), through a mechanism dependent on ligation of the P2X7 receptor. Here we review the role of extracellular nucleotides as sensors of intracellular bacteria and protozoan parasites, and discuss how these pathogens manipulate purinergic signaling to diminish the immune response against infection. PMID:22634346

Coutinho-Silva, Robson; Ojcius, David M.

2014-01-01

261

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

Code of Federal Regulations, 2012 CFR

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

2012-01-01

262

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

Code of Federal Regulations, 2010 CFR

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

2010-01-01

263

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

Code of Federal Regulations, 2011 CFR

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

2011-01-01

264

Neurofilaments are obligate heteropolymers in vivo  

PubMed Central

Neurofilaments (NFs), composed of three distinct subunits NF-L, NF-M, and NF-H, are neuron-specific intermediate filaments present in most mature neurons. Using DNA transfection and mice expressing NF transgenes, we find that despite the ability of NF-L alone to assemble into short filaments in vitro NF-L cannot form filament arrays in vivo after expression either in cultured cells or in transgenic oligodendrocytes that otherwise do not contain a cytoplasmic intermediate filament (IF) array. Instead, NF-L aggregates into punctate or sheet like structures. Similar nonfilamentous structures are also formed when NF-M or NF-H is expressed alone. The competence of NF-L to assemble into filaments is fully restored by coexpression of NF- M or NF-H to a level approximately 10% of that of NF-L. Deletion of the head or tail domain of NF-M or substitution of the NF-H tail onto an NF- L subunit reveals that restoration of in vivo NF-L assembly competence requires an interaction provided by the NF-M or NF-H head domains. We conclude that, contrary to the expectation drawn from earlier in vitro assembly studies, NF-L is not sufficient to assemble an extended filament network in an in vivo context and that neurofilaments are obligate heteropolymers requiring NF-L and NF-M or NF-H. PMID:8376466

1993-01-01

265

26 CFR 1.163-4 - Deduction for original issue discount on certain obligations issued after May 27, 1969.  

Code of Federal Regulations, 2010 CFR

...certain obligations issued after May 27, 1969. 1.163-4 Section 1.163-4...certain obligations issued after May 27, 1969. (a) In general. ...respect of obligations issued after May 27, 1969, other than— (1) Obligations...

2010-04-01

266

Intracellular Helicobacter pylori in gastric epithelial progenitors  

PubMed Central

Helicobacter pylori is generally viewed as an extracellular pathogen. We have analyzed the tropism of H. pylori clinical isolates in a gnotobiotic transgenic mouse model of human chronic atrophic gastritis, a preneoplastic condition. These mice lack acid-producing parietal cells and have an amplified population of dividing gastric epithelial progenitors (GEPs) that express NeuAc?2,3Gal?1,4-glycans recognized by H. pylori adhesins. Scanning confocal and transmission electron microscopic studies of stomachs that had been colonized for 1 month or 1 year revealed intracellular bacterial collections (IBCs) in a small subset of multi- and oligopotential epithelial progenitors. Transmission electron microscopic and multilabel immunohistochemical analyses disclosed bacteria with several morphotypes, including spiral-shaped, in the cytoplasm and endosomes. Several stages in IBC evolution were documented, from a few solitary bacteria to consolidated populations in dividing and nondividing GEPs, to microorganisms traversing breaches in the GEP plasma cell membrane. IBC formation was not a unique feature of H. pylori strains isolated from patients with chronic atrophic gastritis. The notion that adult mammalian epithelial progenitors can function as a repository for H. pylori broadens the view of host habitats available to this and perhaps other pathogens. PMID:15795379

Oh, Jung D.; Karam, Sherif M.; Gordon, Jeffrey I.

2005-01-01

267

Importance of branched-chain amino Acid utilization in francisella intracellular adaptation.  

PubMed

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

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

2015-01-01

268

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2012 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...

2012-04-01

269

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2014 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...

2014-04-01

270

23 CFR 450.332 - Annual listing of obligated projects.  

Code of Federal Regulations, 2013 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...

2013-04-01

271

45 CFR 1226.13 - Obligations of sponsors.  

Code of Federal Regulations, 2010 CFR

... Regulations Relating to Public Welfare (Continued) CORPORATION FOR NATIONAL AND COMMUNITY SERVICE PROHIBITIONS ON ELECTORAL AND LOBBYING ACTIVITIES Sponsor Employee Activities § 1226.13 Obligations of sponsors. (a) It shall be the...

2010-10-01

272

45 CFR 1226.13 - Obligations of sponsors.  

Code of Federal Regulations, 2011 CFR

... Regulations Relating to Public Welfare (Continued) CORPORATION FOR NATIONAL AND COMMUNITY SERVICE PROHIBITIONS ON ELECTORAL AND LOBBYING ACTIVITIES Sponsor Employee Activities § 1226.13 Obligations of sponsors. (a) It shall be the...

2011-10-01

273

34 CFR 686.43 - Obligation to repay the grant.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

274

34 CFR 686.40 - Documenting the service obligation.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

275

Obligation Policies: An Enforcement Platform Pedro Gama, Paulo Ferreira  

E-print Network

Obligation Policies: An Enforcement Platform Pedro Gama, Paulo Ferreira INESC-ID/IST Distributed Systems Group Rua Alves Redol, no 9, 1000-029 Lisboa [pedro.gama, paulo.ferreira]@gsd.inesc-id.pt Abstract

Ferreira, Paulo

276

29 CFR 500.100 - Vehicle safety obligations.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Vehicle safety obligations. 500.100 Section...AGRICULTURAL WORKER PROTECTION Motor Vehicle Safety and Insurance for Transportation...and Health for Migrant Workers Motor Vehicle Safety § 500.100 Vehicle...

2010-07-01

277

45 CFR 303.6 - Enforcement of support obligations.  

Code of Federal Regulations, 2010 CFR

...obligations. 303.6 Section 303.6 Public Welfare Regulations Relating to Public Welfare OFFICE OF CHILD SUPPORT ENFORCEMENT (CHILD SUPPORT ENFORCEMENT PROGRAM), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN...

2010-10-01

278

47 CFR 25.701 - Public interest obligations.  

Code of Federal Regulations, 2013 CFR

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Public Interest Obligations...Entities licensed to operate satellites in the 12.2 to 12.7 GHz...

2013-10-01

279

47 CFR 25.701 - Public interest obligations.  

Code of Federal Regulations, 2011 CFR

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Public Interest Obligations...Entities licensed to operate satellites in the 12.2 to 12.7 GHz...

2011-10-01

280

47 CFR 25.701 - Public interest obligations.  

Code of Federal Regulations, 2012 CFR

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Public Interest Obligations...Entities licensed to operate satellites in the 12.2 to 12.7 GHz...

2012-10-01

281

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

282

7 CFR 760.507 - Obligations of a participant.  

Code of Federal Regulations, 2014 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...

2014-01-01

283

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

284

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

285

7 CFR 760.507 - Obligations of a participant.  

Code of Federal Regulations, 2013 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...

2013-01-01

286

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

287

38 CFR 17.633 - Deferment of obligated service.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

288

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2014 CFR

...Interpretation of the Fringe Benefits Provisions of the Davis-Bacon Act § 5.31 Meeting wage determination obligations. ...contractor or subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage...

2014-07-01

289

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2012 CFR

...Interpretation of the Fringe Benefits Provisions of the Davis-Bacon Act § 5.31 Meeting wage determination obligations. ...contractor or subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage...

2012-07-01

290

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2011 CFR

...Interpretation of the Fringe Benefits Provisions of the Davis-Bacon Act § 5.31 Meeting wage determination obligations. ...contractor or subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage...

2011-07-01

291

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2013 CFR

...Interpretation of the Fringe Benefits Provisions of the Davis-Bacon Act § 5.31 Meeting wage determination obligations. ...contractor or subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage...

2013-07-01

292

29 CFR 5.31 - Meeting wage determination obligations.  

Code of Federal Regulations, 2010 CFR

...Interpretation of the Fringe Benefits Provisions of the Davis-Bacon Act § 5.31 Meeting wage determination obligations. ...contractor or subcontractor performing work subject to a Davis-Bacon wage determination may discharge his minimum wage...

2010-07-01

293

78 FR 49994 - Federal Management Regulation (FMR); Obligating Authority  

Federal Register 2010, 2011, 2012, 2013, 2014

...RIN 3090-AJ35 Federal Management Regulation (FMR); Obligating...proposing to amend the Federal Management Regulation (FMR) to recommend...Lee Gregory, Office of Asset and Transportation Management (MA), Office of...

2013-08-16

294

10 CFR 600.29 - Fixed obligation awards.  

Code of Federal Regulations, 2014 CFR

...subject to the following requirements: (1) Each fixed obligation award may neither exceed $250,000 nor exceed one year in length. (2) Programs which require mandatory cost sharing are not eligible. (3) Proposed costs must be...

2014-01-01

295

18 CFR 37.8 - Obligations of OASIS users.  

Code of Federal Regulations, 2010 CFR

...REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT OPEN ACCESS SAME-TIME INFORMATION SYSTEMS § 37.8 Obligations of OASIS users. Each OASIS user must notify the Responsible Party one month...

2010-04-01

296

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

297

47 CFR 25.701 - Public interest obligations.  

Code of Federal Regulations, 2014 CFR

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Public Interest Obligations...Entities licensed to operate satellites in the 12.2 to 12.7 GHz...

2014-10-01

298

32 CFR 220.9 - Rights and obligations of beneficiaries.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

299

32 CFR 220.9 - Rights and obligations of beneficiaries.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

300

32 CFR 220.9 - Rights and obligations of beneficiaries.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

301

32 CFR 220.9 - Rights and obligations of beneficiaries.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

302

32 CFR 220.9 - Rights and obligations of beneficiaries.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

303

47 CFR 211.7 - Obligation of carriers.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Obligation of carriers. 211.7 Section 211.7 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL EMERGENCY RESTORATION PRIORITY PROCEDURES FOR TELECOMMUNICATIONS SERVICES §...

2010-10-01

304

22 CFR 233.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2014 CFR

...obligations. 233.07 Section 233.07 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT HASHEMITE KINGDOM OF JORDAN LOAN GUARANTEES ISSUED UNDER THE FURTHER CONTINUING APPROPRIATIONS ACT, 2013, DIV. F, PUB. L. 113-6-STANDARD...

2014-04-01

305

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

306

INTRACELLULAR SIGNALING AND DEVELOPMENTAL NEUROTOXICITY.  

EPA Science Inventory

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

307

IcgA Is a Virulence Factor of Rhodococcus equi That Modulates Intracellular Growth  

PubMed Central

Virulence of the intracellular pathogen Rhodococcus equi depends on a 21.3-kb pathogenicity island located on a conjugative plasmid. To date, the only nonregulatory pathogenicity island-encoded virulence factor identified is the cell envelope-associated VapA protein. Although the pathogenicity islands from porcine and equine R. equi isolates have undergone major rearrangements, the virR operon (virR-icgA-vapH-orf7-virS) is highly conserved in both, suggesting these genes play an important role in pathogenicity. VirR and VirS are transcriptional regulators controlling expression of pathogenicity island genes, including vapA. Here, we show that while vapH and orf7 are dispensable for intracellular growth of R. equi, deletion of icgA, formerly known as orf5, encoding a major facilitator superfamily transport protein, elicited an enhanced growth phenotype in macrophages and a significant reduction in macrophage viability, while extracellular growth in broth remained unaffected. Transcription of virS, located downstream of icgA, and vapA was not affected by the icgA deletion during growth in broth or in macrophages, showing that the enhanced growth phenotype caused by deletion of icgA was not mediated through abnormal transcription of these genes. Transcription of icgA increased 6-fold within 2 h following infection of macrophages and remained significantly higher 48 h postinfection compared to levels at the start of the infection. The major facilitator superfamily transport protein IcgA is the first factor identified in R. equi that negatively affects intracellular replication. Aside from VapA, it is only the second pathogenicity island-encoded structural protein shown to play a direct role in intracellular growth of this pathogenic actinomycete. PMID:24549327

Wang, Xiaoguang; Coulson, Garry B.; Miranda-CasoLuengo, Aleksandra A.; Miranda-CasoLuengo, Raúl; Hondalus, Mary K.

2014-01-01

308

A Francisella tularensis Pathogenicity Island Required for Intramacrophage Growth  

Microsoft Academic Search

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

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

2004-01-01

309

Mechanisms of Borrelia burgdorferi internalization and intracellular innate immune signaling  

PubMed Central

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

Petnicki-Ocwieja, Tanja; Kern, Aurelie

2014-01-01

310

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

311

Temporal Dynamics of Outcrossing and Host Mortality Rates in Host-Pathogen Experimental Coevolution  

PubMed Central

Cross-fertilization is predicted to facilitate the short-term response and the long-term persistence of host populations engaged in antagonistic coevolutionary interactions. Consistent with this idea, our previous work has shown that coevolving bacterial pathogens (Serratia marcescens) can drive obligately selfing hosts (Caenorhabditis elegans) to extinction, while the obligately outcrossing and partially outcrossing populations persisted. We focused the present study on the partially outcrossing (mixed mating) and obligately outcrossing hosts, and analyzed the changes in the host resistance/avoidance (and pathogen infectivity) over time. We found that host mortality rates increased in the mixed mating populations over the first ten generations of coevolution when outcrossing rates were initially low. However, mortality rates decreased after elevated outcrossing rates evolved during the experiment. In contrast, host mortality rates decreased in the obligately outcrossing populations during the first ten generations of coevolution, and remained low throughout the experiment. Therefore, predominant selfing reduced the ability of the hosts to respond to coevolving pathogens compared to outcrossing hosts. Thus, we found that host-pathogen coevolution can generate rapid evolutionary change, and that host mating system can influence the outcome of coevolution at a fine temporal scale. PMID:23815644

Morran, Levi T.; Parrish, Raymond C.; Gelarden, Ian A.; Lively, Curtis M.

2012-01-01

312

Iron in intracellular infection: to provide or to deprive?  

PubMed Central

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

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

2013-01-01

313

The sunflower downy mildew pathogen Plasmopara halstedii.  

PubMed

Downy mildew of sunflower is caused by Plasmopara halstedii (Farlow) Berlese & de Toni. Plasmopara halstedii is an obligate biotrophic oomycete pathogen that attacks annual Helianthus species and cultivated sunflower, Helianthus annuus. Depending on the sunflower developmental stage at which infection occurs, the characteristic symptoms range from young seedling death, plant dwarfing, leaf bleaching and sporulation to the production of infertile flowers. Downy mildew attacks can have a great economic impact on sunflower crops, and several Pl resistance genes are present in cultivars to protect them against the disease. Nevertheless, some of these resistances have been overcome by the occurrence of novel isolates of the pathogen showing increased virulence. A better characterization of P.?halstedii infection and dissemination mechanisms, and the identification of the molecular basis of the interaction with sunflower, is a prerequisite to efficiently fight this pathogen. This review summarizes what is currently known about P.?halstedii, provides new insights into its infection cycle on resistant and susceptible sunflower lines using scanning electron and light microscopy imaging, and sheds light on the pathogenicity factors of P.?halstedii obtained from recent molecular data. PMID:25476405

Gascuel, Quentin; Martinez, Yves; Boniface, Marie-Claude; Vear, Felicity; Pichon, Magalie; Godiard, Laurence

2014-12-01

314

Deciphering the Intracellular Fate of Propionibacterium acnes in Macrophages  

PubMed Central

Propionibacterium acnes is a Gram-positive bacterium that colonizes various niches of the human body, particularly the sebaceous follicles of the skin. Over the last years a role of this common skin bacterium as an opportunistic pathogen has been explored. Persistence of P. acnes in host tissue has been associated with chronic inflammation and disease development, for example, in prostate pathologies. This study investigated the intracellular fate of P. acnes in macrophages after phagocytosis. In a mouse model of P. acnes-induced chronic prostatic inflammation, the bacterium could be detected in prostate-infiltrating macrophages at 2 weeks postinfection. Further studies performed in the human macrophage cell line THP-1 revealed intracellular survival and persistence of P. acnes but no intracellular replication or escape from the host cell. Confocal analyses of phagosome acidification and maturation were performed. Acidification of P. acnes-containing phagosomes was observed at 6 h postinfection but then lost again, indicative of cytosolic escape of P. acnes or intraphagosomal pH neutralization. No colocalization with the lysosomal markers LAMP1 and cathepsin D was observed, implying that the P. acnes-containing phagosome does not fuse with lysosomes. Our findings give first insights into the intracellular fate of P. acnes; its persistency is likely to be important for the development of P. acnes-associated inflammatory diseases. PMID:23862148

Fischer, Natalie; Mak, Tim N.; Shinohara, Debika Biswal; Sfanos, Karen S.; Meyer, Thomas F.

2013-01-01

315

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

316

Phenotypic Mutants of the Intracellular Actinomycete Rhodococcusequi Created by In Vivo Himar1 Transposon Mutagenesis  

Microsoft Academic Search

Rhodococcus equi is a facultative intracellular opportunistic pathogen of immunocompromised people and a major cause of pneumonia in young horses. An effective live attenuated vaccine would be extremely useful in the prevention of R. equi disease in horses. Toward that end, we have developed an efficient transposon mutagenesis system that makes use of a Himar1 minitransposon delivered by a conditionally

Joseph Ashour; Mary K. Hondalus

2003-01-01

317

Analysis of Ten Brucella Genomes Reveals Evidence for Horizontal Gene Transfer Despite a Preferred Intracellular Lifestyle  

Microsoft Academic Search

The facultative intracellular bacterial pathogen Brucella infects a wide range of warm-blooded land and marine vertebrates and causes brucellosis. Currently, there are nine recognized Brucella species based on host preferences and phenotypic differences. The availability of 10 different genomes consisting of two chromosomes and representing six of the species allowed for a detailed comparison among themselves and relatives in the

Alice R. Wattam; Kelly P. Williams; Eric E. Snyder; Nalvo F. Almeida; Maulik Shukla; A. W. Dickerman; O. R. Crasta; R. Kenyon; J. Lu; J. M. Shallom; H. Yoo; T. A. Ficht; R. M. Tsolis; C. Munk; R. Tapia; C. S. Han; J. C. Detter; D. Bruce; T. S. Brettin; Bruno W. Sobral; Stephen M. Boyle; Joao C. Setubal

2009-01-01

318

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

319

he molecular basis of the pathogenicity of in-  

E-print Network

viruses such as HIV and intracellular bacterial pathogens such as Listeria and Salmonella, restricts growth and pathfinding, apoptosis and intra- and intercellular signalling pathways, to give but a few . The bacteria produce this toxin when they are cultured on high-osmolarity medium. If the nematode is exposed

Ewbank, Jonathan

320

Portrait of a Pathogen: The Mycobacterium tuberculosis Proteome In Vivo  

Microsoft Academic Search

BackgroundMycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is a facultative intracellular pathogen that can persist within the host. The bacteria are thought to be in a state of reduced replication and metabolism as part of the chronic lung infection. Many in vitro studies have dissected the hypothesized environment within the infected lung, defining the bacterial response to pH,

Nicole A. Kruh; Jolynn Troudt; Angelo Izzo; Jessica Prenni; Karen M. Dobos; Ramy K. Aziz

2010-01-01

321

Molecular Characterization and Evolution of Arthropod-Pathogenic Rickettsiella Bacteria  

Microsoft Academic Search

Members of the genus Rickettsiella are intracellular bacterial pathogens of arthropods (13). They are found in a wide range of hosts including insects, crustaceans, and arachnids, and they exhibit a worldwide geographic distribution (11-13). In natu- rally infected hosts, the Rickettsiella-mediated disease affects both larvae and adults and develops very slowly (13). In its crustacean hosts, \\

Richard Cordaux; Melanie Paces-Fessy; Maryline Raimond; Alice Michel-Salzat; Martin Zimmer; Didier Bouchon

2007-01-01

322

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

SciTech Connect

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

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

2006-07-21

323

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

324

Linking the Transcriptional Profiles and the Physiological States of Mycobacterium tuberculosis during an Extended Intracellular Infection  

PubMed Central

Intracellular pathogens such as Mycobacterium tuberculosis have evolved strategies for coping with the pressures encountered inside host cells. The ability to coordinate global gene expression in response to environmental and internal cues is one key to their success. Prolonged survival and replication within macrophages, a key virulence trait of M. tuberculosis, requires dynamic adaptation to diverse and changing conditions within its phagosomal niche. However, the physiological adaptations during the different phases of this infection process remain poorly understood. To address this knowledge gap, we have developed a multi-tiered approach to define the temporal patterns of gene expression in M. tuberculosis in a macrophage infection model that extends from infection, through intracellular adaptation, to the establishment of a productive infection. Using a clock plasmid to measure intracellular replication and death rates over a 14-day infection and electron microscopy to define bacterial integrity, we observed an initial period of rapid replication coupled with a high death rate. This was followed by period of slowed growth and enhanced intracellular survival, leading finally to an extended period of net growth. The transcriptional profiles of M. tuberculosis reflect these physiological transitions as the bacterium adapts to conditions within its host cell. Finally, analysis with a Transcriptional Regulatory Network model revealed linked genetic networks whereby M. tuberculosis coordinates global gene expression during intracellular survival. The integration of molecular and cellular biology together with transcriptional profiling and systems analysis offers unique insights into the host-driven responses of intracellular pathogens such as M. tuberculosis. PMID:22737072

Rohde, Kyle H.; Veiga, Diogo F. T.; Caldwell, Shannon; Balázsi, Gábor; Russell, David G.

2012-01-01

325

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

PubMed

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

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

2015-02-01

326

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

327

Quantitative Proteomics of Intracellular Campylobacter jejuni Reveals Metabolic Reprogramming  

PubMed Central

Campylobacter jejuni is the major cause of bacterial food-borne illness in the USA and Europe. An important virulence attribute of this bacterial pathogen is its ability to enter and survive within host cells. Here we show through a quantitative proteomic analysis that upon entry into host cells, C. jejuni undergoes a significant metabolic downshift. Furthermore, our results indicate that intracellular C. jejuni reprograms its respiration, favoring the respiration of fumarate. These results explain the poor ability of C. jejuni obtained from infected cells to grow under standard laboratory conditions and provide the bases for the development of novel anti microbial strategies that would target relevant metabolic pathways. PMID:22412372

Liu, Xiaoyun; Gao, Beile; Novik, Veronica; Galán, Jorge E.

2012-01-01

328

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

329

Pathogen life-history trade-offs revealed in allopatry.  

PubMed

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

2013-11-01

330

PATHOGENS: VIEWS OF EPA'S PATHOGEN EQUIVALENCY COMMITTEE  

EPA Science Inventory

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

331

Evolution of Antigen Variation in the Tick-Borne Pathogen Anaplasma phagocytophilum  

PubMed Central

Anaplasma phagocytophilum is an obligately intracellular tick-transmitted bacterial pathogen of humans and other animals. During the course of infection, A. phagocytophilum utilizes gene conversion to shuffle ?100 functional pseudogenes into a single expression cassette of the msp2(p44) gene, which codes for the major surface antigen and major surface protein 2 (MSP2). The role and extent of msp2(p44) recombination, particularly in hosts that only experience acute infections, is not clear. In the present study, we explored patterns of recombination and expression of the msp2(p44) gene of A. phagocytophilum in a serially infected mouse model. Even though the bacterium was passed rapidly among mice, minimizing the opportunities for the host to develop adaptive immunity, we detected the emergence of 34 unique msp2(p44) expression cassette variants. The expression of msp2(p44) pseudogenes did not follow a consistent pattern among different groups of mice, although some pseudogenes were expressed more frequently than others. In addition, among 263 expressed pseudogenes, 3 mosaic sequences each consisting of 2 different pseudogenes were identified. Population genetic analysis showed that genetic diversity and subpopulation differentiation tended to increase over time until stationarity was reached but that the variance that was observed in allele (expressed pseudogene) frequency could occur by drift alone only if a high variance in bacterial reproduction could be assumed. These findings suggest that evolutionary forces influencing antigen variation in A. phagocytophilum may comprise random genetic drift as well as some innate but apparently nonpurifying selection prior to the strong frequency-dependent selection that occurs cyclically after hosts develop strong adaptive immunity. PMID:21965342

Rejmanek, Daniel; Foley, Patrick; Barbet, Anthony; Foley, Janet

2012-01-01

332

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

333

A test for obligate apomixis in grain sorghum R473  

Microsoft Academic Search

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

D. R. Marshall; R. W. Downes

1977-01-01

334

Changing Families, Changing Responsibilities: Family Obligations Following Divorce and Remarriage.  

ERIC Educational Resources Information Center

The high incidence of divorce and remarriage means that the structure of American families is changing. Drawing on 13 studies that explore intergenerational obligations, this book discusses the responsibilities of family members to one another after divorce and remarriage. Chapter 1, "Who Is Responsible for Dependent Family Members?," presents an…

Ganong, Lawrence H.; Coleman, Marilyn

335

7 CFR 930.163 - Deferment of restricted obligation.  

Code of Federal Regulations, 2013 CFR

...NUTS), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW...a surety bond on restricted percentage cherries to be posted to temporarily defer the...times the market value of the quantity of cherries for which the holding obligation...

2013-01-01

336

7 CFR 930.163 - Deferment of restricted obligation.  

Code of Federal Regulations, 2012 CFR

...Nuts), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW...a surety bond on restricted percentage cherries to be posted to temporarily defer the...times the market value of the quantity of cherries for which the holding obligation...

2012-01-01

337

7 CFR 930.163 - Deferment of restricted obligation.  

Code of Federal Regulations, 2011 CFR

...Nuts), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW...a surety bond on restricted percentage cherries to be posted to temporarily defer the...times the market value of the quantity of cherries for which the holding obligation...

2011-01-01

338

7 CFR 930.163 - Deferment of restricted obligation.  

Code of Federal Regulations, 2014 CFR

...NUTS), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW...a surety bond on restricted percentage cherries to be posted to temporarily defer the...times the market value of the quantity of cherries for which the holding obligation...

2014-01-01

339

7 CFR 930.163 - Deferment of restricted obligation.  

Code of Federal Regulations, 2010 CFR

...Nuts), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW...a surety bond on restricted percentage cherries to be posted to temporarily defer the...times the market value of the quantity of cherries for which the holding obligation...

2010-01-01

340

INTRACELLULAR HEMOLYSIN OF PSEUDOMONAS AERUGINOSA  

PubMed Central

Berk, Richard S. (Wayne State University, Detroit, Mich.). Intracellular hemolysin of Pseudomonas aeruginosa. J. Bacteriol. 85:522–526. 1963.—Disruption of cells (2 to 6 days old) of Pseudomonas aeruginosa grown in Tryptose Broth devoid of blood yielded an intracellular hemolysin active on sheep and human erythrocytes. The intracellular agent was not usually detectable in cells grown under highly aerobic conditions. However, activity was observed after 48 hr of growth and appeared to reach a peak at 96 hr when grown under static conditions. Centrifugation of hemolytic extracts at 20,000 × g for 30 min resulted in a fractionation of activity into particulate and soluble components. Similar fractionation of activity occurred after adjustment of the pH of crude extracts to 1.40. In addition, hemolytic preparations were not inactivated by boiling for 90 min, by treatment with ethylenediaminetetraacetate, or by heating in equal volumes of 20% KOH. Activity over a wide pH range was noted, with a maximum occurring at approximately 6.0. However, some preparations occasionally exhibited a second peak on the alkaline side. PMID:14042927

Berk, Richard S.

1963-01-01

341

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

342

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

343

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

344

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

345

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

346

48 CFR 13.202 - Unenforceability of unauthorized obligations in micro-purchases.  

Code of Federal Regulations, 2013 CFR

...Unenforceability of unauthorized obligations in micro-purchases. 13.202 Section 13...ACQUISITION PROCEDURES Actions at or Below the Micro-Purchase Threshold 13.202 Unenforceability of unauthorized obligations in micro-purchases. Many...

2013-10-01

347

48 CFR 13.202 - Unenforceability of unauthorized obligations in micro-purchases.  

Code of Federal Regulations, 2014 CFR

...Unenforceability of unauthorized obligations in micro-purchases. 13.202 Section 13...ACQUISITION PROCEDURES Actions at or Below the Micro-Purchase Threshold 13.202 Unenforceability of unauthorized obligations in micro-purchases. Many...

2014-10-01

348

24 CFR 905.120 - Penalties for slow obligation or expenditure of Capital Fund program assistance.  

Code of Federal Regulations, 2011 CFR

...Penalties for slow obligation or expenditure of Capital Fund program assistance. 905.120 Section 905.120...AND URBAN DEVELOPMENT THE PUBLIC HOUSING CAPITAL FUND PROGRAM Capital Fund § 905.120 Penalties for slow obligation or...

2011-04-01

349

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

Code of Federal Regulations, 2010 CFR

28 Judicial Administration...to promote compliance with crime victims' rights obligations...to promote compliance with crime victims' rights obligations...protection of the rights of crime victims. See 18 U.S.C....

2010-07-01

350

45 CFR 402.26 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2014 CFR

...true Time period for obligation and expenditure of grant funds. 402.26 Section...CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES STATE LEGALIZATION...26 Time period for obligation and expenditure of grant funds. (a) Any...

2014-10-01

351

45 CFR 402.26 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2010 CFR

...false Time period for obligation and expenditure of grant funds. 402.26 Section...CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES STATE LEGALIZATION...26 Time period for obligation and expenditure of grant funds. (a) Any...

2010-10-01

352

45 CFR 402.26 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2012 CFR

...false Time period for obligation and expenditure of grant funds. 402.26 Section...CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES STATE LEGALIZATION...26 Time period for obligation and expenditure of grant funds. (a) Any...

2012-10-01

353

45 CFR 402.26 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2013 CFR

...true Time period for obligation and expenditure of grant funds. 402.26 Section...CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES STATE LEGALIZATION...26 Time period for obligation and expenditure of grant funds. (a) Any...

2013-10-01

354

45 CFR 402.26 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2011 CFR

...false Time period for obligation and expenditure of grant funds. 402.26 Section...CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES STATE LEGALIZATION...26 Time period for obligation and expenditure of grant funds. (a) Any...

2011-10-01

355

14 CFR 323.18 - Carriers' obligations when terminating, suspending, or reducing air service.  

Code of Federal Regulations, 2010 CFR

... Carriers' obligations when terminating, suspending, or reducing air service. 323.18 Section 323.18 Aeronautics and... Carriers' obligations when terminating, suspending, or reducing air service. Any air carrier that terminates,...

2010-01-01

356

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

Code of Federal Regulations, 2013 CFR

...the obligations may be transmitted by gift, bequest, or inheritance. (vi) A declaration that the election is made under...the obligation may be transmitted by gift, bequest, or inheritance. Therefore, all payments received to which the...

2013-04-01

357

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

Code of Federal Regulations, 2014 CFR

...the obligations may be transmitted by gift, bequest, or inheritance. (vi) A declaration that the election is made under...the obligation may be transmitted by gift, bequest, or inheritance. Therefore, all payments received to which the...

2014-04-01

358

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

Code of Federal Regulations, 2011 CFR

...the obligations may be transmitted by gift, bequest, or inheritance. (vi) A declaration that the election is made under...the obligation may be transmitted by gift, bequest, or inheritance. Therefore, all payments received to which the...

2011-04-01

359

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

Code of Federal Regulations, 2012 CFR

...the obligations may be transmitted by gift, bequest, or inheritance. (vi) A declaration that the election is made under...the obligation may be transmitted by gift, bequest, or inheritance. Therefore, all payments received to which the...

2012-04-01

360

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

Code of Federal Regulations, 2010 CFR

...the obligations may be transmitted by gift, bequest, or inheritance. (vi) A declaration that the election is made under...the obligation may be transmitted by gift, bequest, or inheritance. Therefore, all payments received to which the...

2010-04-01

361

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

362

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

363

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

364

43 CFR 3137.71 - What must I do to meet continuing development obligations?  

Code of Federal Regulations, 2012 CFR

...What must I do to meet continuing development obligations? 3137.71 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.71 What must I do to meet continuing development obligations? (a) Once you...

2012-10-01

365

43 CFR 3137.76 - What happens if I do not meet a continuing development obligation?  

Code of Federal Regulations, 2012 CFR

...happens if I do not meet a continuing development obligation? 3137.76 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.76 ...happens if I do not meet a continuing development obligation? (a) After...

2012-10-01

366

43 CFR 3137.71 - What must I do to meet continuing development obligations?  

Code of Federal Regulations, 2011 CFR

...What must I do to meet continuing development obligations? 3137.71 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.71 What must I do to meet continuing development obligations? (a) Once you...

2011-10-01

367

43 CFR 3137.71 - What must I do to meet continuing development obligations?  

Code of Federal Regulations, 2014 CFR

...What must I do to meet continuing development obligations? 3137.71 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.71 What must I do to meet continuing development obligations? (a) Once you...

2014-10-01

368

43 CFR 3137.76 - What happens if I do not meet a continuing development obligation?  

Code of Federal Regulations, 2011 CFR

...happens if I do not meet a continuing development obligation? 3137.76 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.76 ...happens if I do not meet a continuing development obligation? (a) After...

2011-10-01

369

43 CFR 3137.71 - What must I do to meet continuing development obligations?  

Code of Federal Regulations, 2013 CFR

...What must I do to meet continuing development obligations? 3137.71 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.71 What must I do to meet continuing development obligations? (a) Once you...

2013-10-01

370

43 CFR 3137.76 - What happens if I do not meet a continuing development obligation?  

Code of Federal Regulations, 2013 CFR

...happens if I do not meet a continuing development obligation? 3137.76 Section...Agreements-National Petroleum Reserve-Alaska Development Requirements § 3137.76 ...happens if I do not meet a continuing development obligation? (a) After...

2013-10-01

371

78 FR 40953 - Loan Participations; Purchase, Sale and Pledge of Eligible Obligations; Purchase of Assets and...  

Federal Register 2010, 2011, 2012, 2013, 2014

...of Eligible Obligations; Purchase of Assets and Assumption...titled Loan Participations; Purchase, Sale and Pledge of Eligible Obligations; Purchase of Assets and Assumption...credit unions with additional time to prepare to comply...

2013-07-09

372

47 CFR 54.309 - Connect America Fund Phase II Public Interest Obligations.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Connect America Fund Phase II Public Interest Obligations. 54... § 54.309 Connect America Fund Phase II Public Interest Obligations. (a) A price cap carrier electing Phase II model-based support is...

2014-10-01

373

18 CFR 35.1 - Application; obligation to file rate schedules, tariffs and certain service agreements.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Application; obligation to file rate schedules, tariffs and certain service... § 35.1 Application; obligation to file rate schedules, tariffs and certain service... (a) Every public utility shall file with the Commission and...

2010-04-01

374

32 CFR 220.2 - Statutory obligation of third party payer to pay.  

Code of Federal Regulations, 2012 CFR

...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

2012-07-01

375

32 CFR 220.2 - Statutory obligation of third party payer to pay.  

Code of Federal Regulations, 2011 CFR

...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

2011-07-01

376

32 CFR 220.2 - Statutory obligation of third party payer to pay.  

Code of Federal Regulations, 2010 CFR

...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

2010-07-01

377

32 CFR 220.2 - Statutory obligation of third party payer to pay.  

Code of Federal Regulations, 2013 CFR

...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

2013-07-01

378

32 CFR 220.2 - Statutory obligation of third party payer to pay.  

Code of Federal Regulations, 2014 CFR

...COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.2 Statutory obligation of third party...obligation to pay the United States the reasonable charges for healthcare services provided in or through any facility of...

2014-07-01

379

Reward Management Conference 2011 The role of perceived employer obligations in the interpretation of -and  

E-print Network

obligations. This leads to the consideration that employees systematically assess their total reward package. Keywords: psychological contract, total reward, affective commitment, meaning, expatriate hal-006751603rd Reward Management Conference 2011 1 The role of perceived employer obligations

Boyer, Edmond

380

40 CFR 152.97 - Rights and obligations of data submitters.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Rights and obligations of data submitters. 152.97 Section 152...PROCEDURES Procedures To Ensure Protection of Data Submitters' Rights § 152.97 Rights and obligations of data submitters. (a) Right to be...

2010-07-01

381

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

382

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

383

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

384

42 CFR 64a.105 - What are the conditions of obligated service?  

Code of Federal Regulations, 2012 CFR

...105 Section 64a.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING OBLIGATED SERVICE FOR MENTAL HEALTH TRAINEESHIPS § 64a.105 What are the conditions of obligated...

2012-10-01

385

47 CFR 14.61 - Obligations with respect to internet browsers built into mobile phones.  

Code of Federal Regulations, 2013 CFR

... false Obligations with respect to internet browsers built into mobile phones...EQUIPMENT BY PEOPLE WITH DISABILITIES Internet Browsers Built Into Telephones Used With...14.61 Obligations with respect to internet browsers built into mobile phones....

2013-10-01

386

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

Code of Federal Regulations, 2010 CFR

...guidelines for obligations issued for university and housing purposes. 1.130 Section...guidelines for obligations issued for university and housing purposes. (a) Investment... An obligation issued for housing, university, or dormitory purposes is a Type...

2010-01-01

387

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

388

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

389

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

390

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

391

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

392

45 CFR 2553.83 - What financial obligation does the Corporation incur for non-Corporation funded projects?  

Code of Federal Regulations, 2010 CFR

... false What financial obligation does...non-Corporation funded projects? 2553.83...Non-Corporation Funded Projects § 2553.83 What financial obligation does...non-Corporation funded project does not create a financial obligation...

2010-10-01

393

45 CFR 2551.113 - What financial obligation does the Corporation incur for non-Corporation funded projects?  

Code of Federal Regulations, 2010 CFR

... false What financial obligation does...non-Corporation funded projects? 2551.113...Non-Corporation Funded SCP Projects § 2551.113 What financial obligation does...non-Corporation funded project, does not create a financial obligation...

2010-10-01

394

45 CFR 2552.113 - What financial obligation does the Corporation incur for non-Corporation funded projects?  

Code of Federal Regulations, 2010 CFR

... false What financial obligation does...non-Corporation funded projects? 2552.113...Grandparent Program Projects § 2552.113 What financial obligation does...non-Corporation funded project, does not create a financial obligation...

2010-10-01

395

26 CFR 1.163-5 - Denial of interest deduction on certain obligations issued after December 31, 1982, unless issued...  

Code of Federal Regulations, 2010 CFR

...foreign currency denominated obligation will not be treated as linked...dollar solely because the obligation is the subject of a swap transaction. (4 ) Distributor...person that offers or sells the obligation during the restricted...

2010-04-01

396

40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

2014-07-01

397

40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

2012-07-01

398

40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

2011-07-01

399

40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

2010-07-01

400

40 CFR 80.1106 - To whom does the Renewable Volume Obligation apply?  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false To whom does the Renewable Volume Obligation apply? 80.1106 Section...80.1106 To whom does the Renewable Volume Obligation apply? (a) (1...that it has satisfied the Renewable Volume Obligation for that compliance...

2013-07-01

401

31 CFR 225.4 - Pledge of book-entry Government obligations.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

2012-07-01

402

31 CFR 225.4 - Pledge of book-entry Government obligations.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

2014-07-01

403

31 CFR 225.4 - Pledge of book-entry Government obligations.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

2011-07-01

404

31 CFR 225.4 - Pledge of book-entry Government obligations.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

2010-07-01

405

31 CFR 225.4 - Pledge of book-entry Government obligations.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Pledge of book-entry Government obligations. 225.4 Section 225...SERVICE ACCEPTANCE OF BONDS SECURED BY GOVERNMENT OBLIGATIONS IN LIEU OF BONDS WITH SURETIES § 225.4 Pledge of book-entry Government obligations. (a)...

2013-07-01

406

INsPECT, an open-source and versatile software for automated quantification of (Leishmania) intracellular parasites.  

PubMed

Intracellular protozoan parasites are causative agents of infectious diseases that constitute major health problems for developing countries. Leishmania sp., Trypanosoma cruzi or Toxoplasma gondii are all obligate intracellular protozoan parasites that reside and multiply within the host cells of mammals, including humans. Following up intracellular parasite proliferation is therefore an essential and a quotidian task for many laboratories working on primary screening of new natural and synthetic drugs, analyzing drug susceptibility or comparing virulence properties of natural and genetically modified strains. Nevertheless, laborious manual microscopic counting of intracellular parasites is still the most commonly used approach. Here, we present INsPECT (Intracellular ParasitE CounTer), an open-source and platform independent software dedicated to automate infection level measurement based on fluorescent DNA staining. It offers the possibility to choose between different types of analyses (fluorescent DNA acquisitions only or in combination with phase contrast image set to further separate intra- from extracellular parasites), and software running modes (automatic or custom). A proof-of-concept study with intracellular Leishmania infantum parasites stained with DAPI (4',6-diamidino-2-phenylindole) confirms a good correspondence between digital results and the "gold standard" microscopic counting method with Giemsa. Interestingly, this software is versatile enough to accurately detect intracellular T. gondii parasites on images acquired with High Content Screening (HCS) systems. In conclusion, INsPECT software is proposed as a new fast and simple alternative to the classical intracellular Leishmania quantification methods and can be adapted for mid to large-scale drug screening against different intracellular parasites. PMID:24831235

Yazdanparast, Ehsan; Dos Anjos, Antonio; Garcia, Deborah; Loeuillet, Corinne; Shahbazkia, Hamid Reza; Vergnes, Baptiste

2014-05-01

407

INsPECT, an Open-Source and Versatile Software for Automated Quantification of (Leishmania) Intracellular Parasites  

PubMed Central

Intracellular protozoan parasites are causative agents of infectious diseases that constitute major health problems for developing countries. Leishmania sp., Trypanosoma cruzi or Toxoplasma gondii are all obligate intracellular protozoan parasites that reside and multiply within the host cells of mammals, including humans. Following up intracellular parasite proliferation is therefore an essential and a quotidian task for many laboratories working on primary screening of new natural and synthetic drugs, analyzing drug susceptibility or comparing virulence properties of natural and genetically modified strains. Nevertheless, laborious manual microscopic counting of intracellular parasites is still the most commonly used approach. Here, we present INsPECT (Intracellular ParasitE CounTer), an open-source and platform independent software dedicated to automate infection level measurement based on fluorescent DNA staining. It offers the possibility to choose between different types of analyses (fluorescent DNA acquisitions only or in combination with phase contrast image set to further separate intra- from extracellular parasites), and software running modes (automatic or custom). A proof-of-concept study with intracellular Leishmania infantum parasites stained with DAPI (4?,6-diamidino-2-phenylindole) confirms a good correspondence between digital results and the “gold standard” microscopic counting method with Giemsa. Interestingly, this software is versatile enough to accurately detect intracellular T. gondii parasites on images acquired with High Content Screening (HCS) systems. In conclusion, INsPECT software is proposed as a new fast and simple alternative to the classical intracellular Leishmania quantification methods and can be adapted for mid to large-scale drug screening against different intracellular parasites. PMID:24831235

Yazdanparast, Ehsan; Dos Anjos, Antonio; Garcia, Deborah; Loeuillet, Corinne; Shahbazkia, Hamid Reza; Vergnes, Baptiste

2014-01-01

408

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

409

Federal Academic Science and Engineering Obligations Increased More Than 12 Percent Between FY 1998 and FY 1999  

NSF Publications Database

Federal Academic Science and Engineering Obligations Increased More Than 12 Percent Between FY 1998 ... focuses on academic science and engineering obligations. Hypertext Format Portable Document Format ...

410

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

411

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

412

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; Managò, Antonella; Gulbins, Erich; Zoratti, Mario; Szabò, Ildikò

2013-01-01

413

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

414

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

PubMed Central

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

2014-01-01

415

Histoplasma capsulatum utilizes siderophores for intracellular iron acquisition in macrophages.  

PubMed

Histoplasma capsulatum is a dimorphic fungal pathogen that survives and replicates within macrophages (M?). Studies in human and murine M? demonstrate that the intracellular growth of H. capsulatum yeasts is exquisitely sensitive to the availability of iron. As H. capsulatum produces hydroxamate siderophores, we sought to determine if siderophores were required for intracellular survival in M?, and in a murine model of pulmonary histoplasmosis. The expression of SID1 (coding for L-ornithine-N(5)-monooxygenase) was silenced by RNA interference (RNAi) in H. capsulatum strain G217B, and abolished by gene targeting in strain G186AR. G217B SID1-silenced yeasts grew normally in rich medium, did not synthesize siderophores, and were unable to grow on apotransferrin-chelated medium. Their intracellular growth in human and murine M? was significantly decreased compared to wild type (WT) yeasts, but growth was restored to WT levels by the addition of exogenous iron, or restoration of SID1 expression. Similar results were obtained with G186AR ?sid1 yeasts. Compared to WT yeasts, G217B SID1-silenced yeasts demonstrated in C57BL/6 mice significantly reduced growth in the lungs and spleens seven days after infection, and 40% of the mice given a normally lethal inoculum of G217B SID1-silenced yeasts survived. These experiments demonstrate that: (1) SID1 expression is required for siderophore biosynthesis by H. capsulatum strain G217B, (2) SID1 expression is required for optimum intracellular growth in M?, and (3) inhibition of SID1 expression in vivo reduces the virulence of H. capsulatum yeasts. PMID:21341981

Hilty, Jeremy; George Smulian, A; Newman, Simon L

2011-08-01

416

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

417

Spectra of intracellular Fura-2.  

PubMed

In the theory of measurement of calcium ion activity by determination of Fura-2 fluorescence at two excitation wavelengths, the accuracy of the result depends upon the accuracy both of the sample measurements and of the calibration measurements which are made on calcium-bound and free dye. Two factors underlie adequate calibration and accuracy. The first is the elimination of systematic error due to spectral shifts arising from the intracellular environment felt by the dye. To this end, detailed comparisons between complete spectra of both calcium-bound and calcium-free Fura-2 can be used to help separate spectral effects due to light absorption by cellular constituents versus polarity and viscosity of the intracellular milieu. The second major factor which determines accuracy is the experimental uncertainty (in both sample and calibration measurements). For samples in which the ratio of bound to free dye is large, the uncertainty in the ratio is also large, even when it is expressed as a percentage of the ratio itself. The errors in calibration measurements impact on the accuracy of the method primarily through the measurements made at wavelengths which are off the spectral peaks of the bound or free dye, since these are the least accurate. In order to obtain a guide to the choice of wavelengths and estimation of the reliability of results, a mathematical expression is derived for the dependence of the accuracy of the method on the accuracy of both sample and calibration measurements. PMID:1715814

Owen, C S

1991-06-01

418

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

419

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

420

Quantitative proteomics reveals metabolic and pathogenic properties of Chlamydia trachomatis developmental forms  

PubMed Central

Summary Chlamydia trachomatis is an obligate intracellular pathogen responsible for ocular and genital infections of significant public health importance. C. trachomatis undergoes a biphasic developmental cycle alternating between two distinct forms: the infectious elementary body (EB), and the replicative but non-infectious reticulate body (RB). The molecular basis for these developmental transitions and the metabolic properties of the EB and RB forms are poorly understood as these bacteria have traditionally been difficult to manipulate through classical genetic approaches. Using two-dimensional liquid chromatography – tandem mass spectrometry (LC/LC-MS/MS) we performed a large-scale, label-free quantitative proteomic analysis of C. trachomatis LGV-L2 EB and RB forms. Additionally, we carried out LC-MS/MS to analyze the membranes of the pathogen-containing vacuole (“inclusion”). We developed a label-free quantification approaches to measure protein abundance in a mixed-proteome background which we applied for EB and RB quantitative analysis. In this manner, we catalogued the relative distribution of >54% of the predicted proteins in the C. trachomatis LGV-L2 proteome. Proteins required for central metabolism and glucose catabolism were predominant in the EB, whereas proteins associated with protein synthesis, ATP generation and nutrient transport were more abundant in the RB. These findings suggest that the EB is primed for a burst in metabolic activity upon entry, whereas the RB form is geared towards nutrient utilization, a rapid increase in cellular mass, and securing the resources for an impending transition back to the EB form. The most revealing difference between the two forms was the relative deficiency of cytoplasmic factors required for efficient Type III secretion (T3S) in the RB stage at 18 hpi, suggesting a reduced T3S capacity or a low frequency of active T3S apparatus assembled on a “per organism” basis. Our results show that EB and RB proteomes are streamlined to fulfill their predicted biological functions: maximum infectivity for EBs and replicative capacity for RBs. PMID:22014092

Saka, Hector A.; Thompson, J. Will; Chen, Yi-Shan; Kumar, Yadunanda; Dubois, Laura G.; Moseley, M. Arthur; Valdivia, Raphael H.

2011-01-01

421

Pathogenic Microorganisms in Water  

NSDL National Science Digital Library

Pathogenic Microorganisms in Water: Traditionally, groundwater has been used without treatment because the soil acts as a filter, removing pathogenic microorganisms. Some potential sources of pathogens (or disease causing organisms) in groundwater include septic tanks, leaking sewer lines, sewage sludge, intentional groundwater recharge with sewage, irrigation with sewage, direct injection of sewage, domestic solid waste disposal (landfills) and sewage oxidation ponds. The objective of the session is to introduce hydrogeologist to the types of microorganisms, sources of pathogens, and a simple exercise that can be incorporated into a hydrogeology class.

Melissa Lenczewski

422

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

423

Interactions of the human pathogenic Brucella species with their hosts.  

PubMed

Brucellosis is a zoonotic infection caused primarily by the bacterial pathogens Brucella melitensis and B. abortus. It is acquired by consumption of unpasteurized dairy products or by contact with infected animals. Globally, it is one of the most widespread zoonoses, with 500,000 new cases reported each year. In endemic areas, Brucella infections represent a serious public health problem that results in significant morbidity and economic losses. An important feature of the disease is persistent bacterial colonization of the reticuloendothelial system. In this review we discuss recent insights into mechanisms of intracellular survival and immune evasion that contribute to systemic persistence by the pathogenic Brucella species. PMID:21939378

Atluri, Vidya L; Xavier, Mariana N; de Jong, Maarten F; den Hartigh, Andreas B; Tsolis, Renée M

2011-01-01

424

The rickettsia: an emerging group of pathogens in fish.  

PubMed Central

Piscirickettsia salmonis is the first of the previously unrecognized rickettsial pathogens of fish to be fully characterized. Since the recognition of P. salmonis in 1989, the impact of rickettsial pathogens in fish has become increasingly apparent. Growing awareness of the emergence of these fastidious intracellular organisms has led to the discovery of rickettsial diseases among diverse species of fish from different geographic locations and aquatic environments. The source, reservoir, and mode of transmission of these agents as well as appropriate methods of disease prevention and control remain to be established. PMID:9204294

Fryer, J. L.; Mauel, M. J.

1997-01-01

425

Carbon metabolism of intracellular bacteria.  

PubMed

Bacterial metabolism has been studied intensively since the first observations of these 'animalcules' by Leeuwenhoek and their isolation in pure cultures by Pasteur. Metabolic studies have traditionally focused on a small number of model organisms, primarily the Gram negative bacillus Escherichia coli, adapted to artificial culture conditions in the laboratory. Comparatively little is known about the physiology and metabolism of wild microorganisms living in their natural habitats. For approximately 500-1000 species of commensals and symbionts, and a smaller number of pathogenic bacteria, that habitat is the human body. Emerging evidence suggests that the metabolism of bacteria grown in vivo differs profoundly from their metabolism in axenic cultures. PMID:16367862

Muñoz-Elías, Ernesto J; McKinney, John D

2006-01-01

426

Virulence Plasmids of Nonsporulating Gram-Positive Pathogens  

PubMed Central

SUMMARY Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis. PMID:25544937

Van Tyne, Daria; Gilmore, Michael S.

2014-01-01

427

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...

428

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

429

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

430

Intracellular kinase inhibitors selected from combinatorial libraries of designed ankyrin repeat proteins.  

PubMed

The specific intracellular inhibition of protein activity at the protein level allows the determination of protein function in the cellular context. We demonstrate here the use of designed ankyrin repeat proteins as tailor-made intracellular kinase inhibitors. The target was aminoglycoside phosphotransferase (3')-IIIa (APH), which mediates resistance to aminoglycoside antibiotics in pathogenic bacteria and shares structural homology with eukaryotic protein kinases. Combining a selection and screening approach, we isolated 198 potential APH inhibitors from highly diverse combinatorial libraries of designed ankyrin repeat proteins. A detailed analysis of several inhibitors revealed that they bind APH with high specificity and with affinities down to the subnanomolar range. In vitro, the most potent inhibitors showed complete enzyme inhibition, and in vivo, a phenotype comparable with the gene knockout was observed, fully restoring antibiotic sensitivity in resistant bacteria. These results underline the great potential of designed ankyrin repeat proteins for modulation of intracellular protein function. PMID:15851475

Amstutz, Patrick; Binz, H Kaspar; Parizek, Petra; Stumpp, Michael T; Kohl, Andreas; Grütter, Markus G; Forrer, Patrik; Plückthun, Andreas

2005-07-01

431

Are green islands red herrings? Significance of green islands in plant interactions with pathogens and pests.  

PubMed

The term green island was first used to describe an area of living, green tissue surrounding a site of infection by an obligately biotrophic fungal pathogen, differentiated from neighbouring yellowing, senescent tissue. However, it has now been used to describe symptoms formed in response to necrotrophic fungal pathogens, virus infection and infestation by certain insects. In leaves infected by obligate biotrophs such as rust and powdery mildew pathogens, green islands are areas where senescence is retarded, photosynthetic activity is maintained and polyamines accumulate. We propose such areas, in which both host and pathogen cells are alive, be termed green bionissia. By contrast, we propose that green areas associated with leaf damage caused by toxins produced by necrotrophic fungal pathogens be termed green necronissia. A range of biotrophic/hemibiotrophic fungi and leaf-mining insects produce cytokinins and it has been suggested that this cytokinin secretion may be responsible for the green island formation. Indeed, localised cytokinin accumulation may be a common mechanism responsible for green island formation in interactions of plants with biotrophic fungi, viruses and insects. Models have been developed to study if green island formation is pathogen-mediated or host-mediated. They suggest that green bionissia on leaves infected by biotrophic fungal pathogens represent zones of host tissue, altered physiologically to allow the pathogen maximum access to nutrients early in the interaction, thus supporting early sporulation and increasing pathogen fitness. They lead to the suggestion that green islands are 'red herrings', representing no more than the consequence of the infection process and discrete changes in leaf senescence. PMID:18093233

Walters, Dale R; McRoberts, Neil; Fitt, Bruce D L

2008-02-01

432

Flavobacteria as Intracellular Symbionts in Cockroaches  

Microsoft Academic Search

Animal cells are the sole habitat for a variety of bacteria. Molecular sequence data have been used to position a number of these intracellular microorganisms in the overall scheme of eubacterial evolution. Most of them have been classified as proteobacteria or chlamydiae. Here we present molecular evidence placing an intracellular symbiont among the flavobacteria-bacteroides. This microorganism inhabits specialized cells in

Claudio Bandi; Giuseppe Damiani; Lorenzo Magrassi; Aldo Grigolo; Renato Fani; Luciano Sacchi

1994-01-01

433

Intracellular Signaling by the Unfolded Protein  

E-print Network

Intracellular Signaling by the Unfolded Protein Response Sebasti´an Bernales,1 Feroz R. Papa,2 reticulum stress, signal transduction, organelle homeostasis, protein folding, regulated mRNA splicing, translational control Abstract The unfolded protein response (UPR) is an intracellular signaling pathway

Mullins, Dyche

434

Signaling During Pathogen Infection  

NSDL National Science Digital Library

Pathogens infect almost every living organism. In animals, including humans, the diversity of pathogens ranges from viruses, bacteria, and unicellular parasites to complex fungi, worms, and arthropods. Because pathogens have coevolved with their hosts and have sometimes been coopted as symbionts or commensals, each pathogen/host pair represents a striking success story of survival that reflects the biological complexity of both parties. All invading microorganisms face similar problems, such as gaining access to their host, achieving successful replication, and spreading to a similar or different host. It is therefore not surprising that many different pathogens target similar organs, cell types, and even molecules to achieve their goals. However, no two microbial parasites appear to be completely alike. Although they often target similar signaling networks, they do so in subtly different ways to achieve the desired outcome. This review has eight figures, three movies, and 139 citations and emphasizes two well-established signaling pathways that are often activated during the interaction of different pathogens with their host cells. It illustrates a small part of how the dissection of host/pathogen interactions can reveal, on a molecular scale, a nature shaped by evolutionary forces that can rival the great descriptions of our macroscopic world.

Sylvia Munter (University of Heidelberg Medical School; Department of Parasitology REV)

2006-05-16

435

Oscillations in intracellular signaling cascades  

NASA Astrophysics Data System (ADS)

In this paper, we study the oscillatory dynamics of intracellular signaling cascades. We derive a reaction-diffusion model of the mitogen-activated protein kinase cascade, and use it to show how oscillations of the protein kinase concentrations can occur as a function of the depth of the cascade. We find that only cascades with depths of three or more layers undergo oscillatory instabilities. In addition, the oscillatory instability is spatially uniform. Thus, the oscillations synchronize the protein kinase concentrations and result in them being uniformly distributed in the cytosol, despite the presence of protein kinase diffusion. Finally, we show how the oscillations are perturbed when parallel cascades “crosstalk.” We find that the protein kinases in the downstream layers of the cascade are less perturbed than those in the upstream layers. In particular, cascades of three layers are able to maintain the total power of the protein kinase activities at approximately the unperturbed level. Taken together, our results suggest that only cascades of at least three layers can synchronize the oscillations of protein kinases in the cytosol and operate in parallel in the presence of crosstalk without loss of signaling fidelity.

Chiam, K.-H.; Rajagopal, Gunaretnam

2007-06-01

436

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

437

47 CFR 54.802 - Obligations of local exchange carriers and the Administrator.  

Code of Federal Regulations, 2010 CFR

...COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) UNIVERSAL SERVICE Interstate Access Universal Service Support Mechanism § 54.802 Obligations of local exchange carriers and the Administrator. (a) Each Eligible...

2010-10-01

438

25 CFR 163.42 - Obligated service and breach of contract.  

Code of Federal Regulations, 2014 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...

2014-04-01

439

Feast or famine: the host-pathogen battle over amino acids.  

PubMed

Intracellular bacterial pathogens often rely on their hosts for essential nutrients. Host cells, in turn, attempt to limit nutrient availability, using starvation as a mechanism of innate immunity. Here we discuss both host mechanisms of amino acid starvation and the diverse adaptations of pathogens to their nutrient-deprived environments. These processes provide both key insights into immune subversion and new targets for drug development. PMID:23521858

Zhang, Yanjia J; Rubin, Eric J

2013-07-01

440

Dual metabolomics: a novel approach to understanding plant-pathogen interactions.  

PubMed

One of the most well-characterised plant pathogenic interactions involves Arabidopsis thaliana and the bacteria Pseudomonas syringae pathovar tomato (Pst). The standard Pst inoculation procedure involves infiltration of large populations of bacteria into plant leaves which means that metabolite changes cannot be readily assigned to the host or pathogen. A plant cell-pathogen co-culture based approach has been developed where the plant and pathogen cells are separated after 12h of co-culture via differential filtering and centrifugation. Fourier transform infrared (FT-IR) spectroscopy was employed to assess the intracellular metabolomes (metabolic fingerprints) of both host and pathogen and their extruded (extracellular) metabolites (metabolic footprints) under conditions relevant to disease and resistance. We propose that this system will enable the metabolomic profiling of the separated host and pathogen (i.e. 'dual metabolomics') and will facilitate the modelling of reciprocal responses. PMID:20138320

Allwood, J William; Clarke, Andrew; Goodacre, Royston; Mur, Luis A J

2010-04-01

441

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

442

Leishmania panamensis infection and antimonial drugs modulate expression of macrophage drug transporters and metabolizing enzymes: impact on intracellular parasite survival  

PubMed Central

Objectives Treatment failure is multifactorial. Despite the importance of host cell drug transporters and metabolizing enzymes in the accumulation, distribution and metabolism of drugs targeting intracellular pathogens, their impact on the efficacy of antileishmanials is unknown. We examined the contribution of pharmacologically relevant determinants in human macrophages in the antimony-mediated killing of intracellular Leishmania panamensis and its relationship with the outcome of treatment with meglumine antimoniate. Methods Patients with cutaneous leishmaniasis who failed (n?=?8) or responded (n?=?8) to treatment were recruited. Gene expression profiling of pharmacological determinants in primary macrophages was evaluated by quantitative RT–PCR and correlated to the drug-mediated intracellular parasite killing. Functional validation was conducted through short hairpin RNA gene knockdown. Results Survival of L. panamensis after exposure to antimonials was significantly higher in macrophages from patients who failed treatment. Sixteen macrophage drug-response genes were modulated by infection and exposure to meglumine antimoniate. Correlation analyses of gene expression and intracellular parasite survival revealed the involvement of host cell metallothionein-2A and ABCB6 in the survival of Leishmania during exposure to antimonials. ABCB6 was functionally validated as a transporter of antimonial compounds localized in both the cell and phagolysosomal membranes of macrophages, revealing a novel mechanism of host cell-mediated regulation of intracellular drug exposure and parasite survival within phagocytes. Conclusions These results provide insight into host cell mechanisms regulating the intracellular exposure of Leishmania to antimonials and variations among individuals that impact parasite survival. Understanding of host cell determinants of intracellular pharmacokinetics/pharmacodynamics opens new avenues to improved drug efficacy for intracellular pathogens. PMID:23975742

Gómez, Maria Adelaida; Navas, Adriana; Márquez, Ricardo; Rojas, Laura Jimena; Vargas, Deninson Alejandro; Blanco, Victor Manuel; Koren, Roni; Zilberstein, Dan; Saravia, Nancy Gore

2014-01-01

443

Invaded range of the blackberry pathogen Phragmidium violaceum in the Pacific Northwest of the USA and the search for its provenance  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field surveys in 2006 confirmed the rust fungus Phragmidium violaceum was widespread on Rubus armeniacus and R. laciniatus in the Pacific Northwest of the United States. The origin, evidence of a founder effect and dispersal pattern of this obligate biotrophic pathogen in the United States were inve...

444

Identification of genes expressed by Phakopsora pachyrhizi, the pathogen causing soybean rust, at a late stage of infection of susceptible soybean leaves  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soybean is one of the top five agricultural products in the United States and is highly susceptible to P. pachyrhizi, an exotic obligate biotrophic fungus. The amount of genomic information about P. pachyrhizi is small, which limits our understanding of the soybean-soybean rust pathogen interaction ...

445

Activation of NADPH oxidase is essential, but not sufficient, in controlling intracellular multiplication of Burkholderia pseudomallei in primary human monocytes.  

PubMed

Burkholderia pseudomallei is a Gram-negative intracellular bacterium and the causative agent of melioidosis. Innate immune mechanisms against this pathogen, which might contribute to outcomes of melioidosis, are little known. We demonstrated here that B. pseudomallei could activate NADPH oxidase in primary human monocytes as judged by production of reactive oxygen species (ROS) and p40(phox) phosphorylation after infection. However, as similar to other intracellular bacteria, this bacterium was able to resist and multiply inside monocytes despite being able to activate NADPH oxidase. In the presence of NADPH oxidase inhibitor, diphenyleneiodonium or apocynin, intracellular multiplication of B. pseudomallei was significantly increased, suggesting that NADPH oxidase-mediated ROS production is essential in suppressing intracellular multiplication of B. pseudomallei. Additionally, interferon-? (IFN-?)-mediated intracellular killing of B. pseudomallei requires NADPH oxidase activity, even though ROS level was not detected at higher levels in IFN-?-treated infected monocytes. Altogether, these results imply that the activation of NADPH plays an essential role in suppressing intracellular multiplication of B. pseudomallei in human monocytes, although this enzyme is not sufficient to stop intracellular multiplication. PMID:24376210

Wikraiphat, Chanthiwa; Pudla, Matsayapan; Baral, Pankaj; Kitthawee, Sangvorn; Utaisincharoen, Pongsak

2014-06-01

446

Stochastic resonance in an intracellular genetic perceptron.  

PubMed

Intracellular genetic networks are more intelligent than was first assumed due to their ability to learn. One of the manifestations of this intelligence is the ability to learn associations of two stimuli within gene-regulating circuitry: Hebbian-type learning within the cellular life. However, gene expression is an intrinsically noisy process; hence, we investigate the effect of intrinsic and extrinsic noise on this kind of intracellular intelligence. We report a stochastic resonance in an intracellular associative genetic perceptron, a noise-induced phenomenon, which manifests itself in noise-induced increase of response in efficiency after the learning event under the conditions of optimal stochasticity. PMID:24730883

Bates, Russell; Blyuss, Oleg; Zaikin, Alexey

2014-03-01

447

Recognition of bacterial plant pathogens: local, systemic and transgenerational immunity.  

PubMed

Bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. The plant innate immune system comprises extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (NLR) proteins that recognize specific bacterial effectors delivered into host cells. Plants lack the adaptive immune branch present in animals, but still afford flexibility to pathogen attack through systemic and transgenerational resistance. Here, we focus on current research in plant immune responses against bacterial pathogens. Recent studies shed light onto the activation and inactivation of pattern recognition receptors and systemic acquired resistance. New research has also uncovered additional layers of complexity surrounding NLR immune receptor activation, cooperation and sub-cellular localizations. Taken together, these recent advances bring us closer to understanding the web of molecular interactions responsible for coordinating defense responses and ultimately resistance. PMID:23909802

Henry, Elizabeth; Yadeta, Koste A; Coaker, Gitta

2013-09-01

448

Recognition of bacterial plant pathogens: local, systemic and transgenerational immunity  

PubMed Central

Summary Bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. The plant innate immune system is comprised of extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (NLR) proteins that recognize specific bacterial effectors delivered into host cells. Plants lack the adaptive immune branch present in animals, but still afford flexibility to pathogen attack through systemic and transgenerational resistance. Here, we focus on current research in plant immune responses against bacterial pathogens. Recent studies shed light onto the activation and inactivation of pattern recognition receptors and systemic acquired resistance. New research has also uncovered additional layers of complexity surrounding NLR immune receptor activation, cooperation, and sub-cellular localizations. Taken together, these recent advances bring us closer to understanding the web of inter-molecular interactions responsible for coordinating defense responses and ultimately resistance. PMID:23909802

Henry, Elizabeth; Yadeta, Koste A.; Coaker, Gitta

2013-01-01

449

Coxiella burnetii Effector Proteins That Localize to the Parasitophorous Vacuole Membrane Promote Intracellular Replication.  

PubMed

The intracellular bacterial pathogen Coxiella burnetii directs biogenesis of a parasitophorous vacuole (PV) that acquires host endolysosomal components. Formation of a PV that supports C. burnetii replication requires a Dot/Icm type 4B secretion system (T4BSS) that delivers bacterial effector proteins into the host cell cytosol. Thus, a subset of T4BSS effectors are presumed to direct PV biogenesis. Recently, the PV-localized effector protein CvpA was found to promote C. burnetii intracellular growth and PV expansion. We predict additional C. burnetii effectors localize to the PV membrane and regulate eukaryotic vesicle trafficking events that promote pathogen growth. To identify these vacuolar effector proteins, a list of predicted C. burnetii T4BSS substrates was compiled using bioinformatic criteria, such as the presence of eukaryote-like coiled-coil domains. Adenylate cyclase translocation assays revealed 13 proteins were secreted in a Dot/Icm-dependent fashion by C. burnetii during infection of human THP-1 macrophages. Four of the Dot/Icm substrates, termed Coxiella vacuolar protein B (CvpB), CvpC, CvpD, and CvpE, labeled the PV membrane and LAMP1-positive vesicles when ectopically expressed as fluorescently tagged fusion proteins. C. burnetii ?cvpB, ?cvpC, ?cvpD, and ?cvpE mutants exhibited significant defects in intracellular replication and PV formation. Genetic complementation of the ?cvpD and ?cvpE mutants rescued intracellular growth and PV generation, whereas the growth of C. burnetii ?cvpB and ?cvpC was rescued upon cohabitation with wild-type bacteria in a common PV. Collectively, these data indicate C. burnetii encodes multiple effector proteins that target the PV membrane and benefit pathogen replication in human macrophages. PMID:25422265

Larson, Charles L; Beare, Paul A; Voth, Daniel E; Howe, Dale; Cockrell, Diane C; Bastidas, Robert J; Valdivia, Raphael H; Heinzen, Robert A

2015-02-01

450

Nanoparticles for intracellular-targeted drug delivery  

NASA Astrophysics Data System (ADS)

Nanoparticles (NPs) are very promising for the intracellular delivery of anticancer and immunomodulatory drugs, stem cell differentiation biomolecules and cell activity modulators. Although initial studies in the area of intracellular drug delivery have been performed in the delivery of DNA, there is an increasing interest in the use of other molecules to modulate cell activity. Herein, we review the latest advances in the intracellular-targeted delivery of short interference RNA, proteins and small molecules using NPs. In most cases, the drugs act at different cellular organelles and therefore the drug-containing NPs should be directed to precise locations within the cell. This will lead to the desired magnitude and duration of the drug effects. The spatial control in the intracellular delivery might open new avenues to modulate cell activity while avoiding side-effects.

Paulo, Cristiana S. O.; Pires das Neves, Ricardo; Ferreira, Lino S.

2011-12-01

451

Comparative Phylogeography in a Specific and Obligate Pollination Antagonism  

PubMed Central

In specific and obligate interactions the nature and abundance of a given species can have important effects on the survival and population dynamics of associated organisms. In a phylogeographic framework, we therefore expect that the fates of organisms interacting specifically are also tightly interrelated. Here we investigate such a scenario by analyzing the genetic structures of species interacting in an obligate plant-insect pollination lure-and-trap antagonism, involving Arum maculatum (Araceae) and its specific psychodid (Diptera) visitors Psychoda phalaenoides and Psycha grisescens. Because the interaction is asymmetric (i.e., only the plant depends on the insect), we expect the genetic structure of the plant to be related with the historical pollinator availability, yielding incongruent phylogeographic patterns between the interacting organisms. Using insect mtDNA sequences and plant AFLP genome fingerprinting, we inferred the large-scale phylogeographies of each species and the distribution of genetic diversities throughout the sampled range, and evaluated the congruence in their respective genetic structures using hierarchical analyses of molecular variances (AMOVA). Because the composition of pollinator species varies in Europe, we also examined its association with the spatial genetic structure of the plant. Our findings indicate that while the plant presents a spatially well-defined genetic structure, this is not the case in the insects. Patterns of genetic diversities also show dissimilar distributions among the three interacting species. Phylogeographic histories of the plant and its pollinating insects are thus not congruent, a result that would indicate that plant and insect lineages do not share the same glacial and postglacial histories. However, the genetic structure of the plant can, at least partially, be explained by the type of pollinators available at a regional scale. Differences in life-history traits of available pollinators might therefore have influenced the genetic structure of the plant, the dependent organism, in this antagonistic interaction. PMID:22216104

Espíndola, Anahí; Alvarez, Nadir

2011-01-01

452

Identification of Burkholderia pseudomallei genes required for the intracellular life cycle and in vivo virulence.  

PubMed

The bacterial pathogen Burkholderia pseudomallei invades host cells, escapes from endocytic vesicles, multiplies intracellularly, and induces the formation of actin tails and membrane protrusions, leading to direct cell-to-cell spreading. This study was aimed at the identification of B. pseudomallei genes responsible for the different steps of this intracellular life cycle. B. pseudomallei transposon mutants were screened for a reduced ability to form plaques on PtK2 cell monolayers as a result of reduced intercellular spreading. Nine plaque assay mutants with insertions in different open reading frames were selected for further studies. One mutant defective in a hypothetical protein encoded within the Bsa type III secretion system gene cluster was found to be unable to escape from endocytic vesicles after invasion but still multiplied within the vacuoles. Another mutant with a defect in a putative exported protein reached the cytoplasm but exhibited impaired actin tail formation in addition to a severe intracellular growth defect. In four mutants, the transposon had inserted into genes involved in either purine, histidine, or p-aminobenzoate biosynthesis, suggesting that these pathways are essential for intracellular growth. Three mutants with reduced plaque formation were shown to have gene defects in a putative cytidyltransferase, a putative lipoate-protein ligase B, and a hypothetical protein. All nine mutants proved to be significantly attenuated in a murine model of infection, with some mutants being essentially avirulent. In conclusion, we have identified a number of novel major B. pseudomallei virulence genes which are essential for the intracellular life cycle of this pathogen. PMID:16714590

Pilatz, Sabine; Breitbach, Katrin; Hein, Nadine; Fehlhaber, Beate; Schulze, Jessika; Brenneke, Birgit; Eberl, Leo; Steinmetz, Ivo

2006-06-01

453

Association of ActA to Peptidoglycan Revealed by Cell Wall Proteomics of Intracellular Listeria monocytogenes*  

PubMed Central

Listeria monocytogenes is a Gram-positive intracellular bacterial pathogen that colonizes the cytosol of eukaryotic cells. Recent transcriptomic studies have revealed that intracellular L. monocytogenes alter expression of genes encoding envelope components. However, no comparative global analysis of this cell wall remodeling process is yet known at the protein level. Here, we used high resolution mass spectrometry to define the cell wall proteome of L. monocytogenes growing inside epithelial cells. When compared with extracellular bacteria growing in a nutrient-rich medium, a major difference found in the proteome was the presence of the actin assembly-inducing protein ActA in peptidoglycan purified from intracellular bacteria. ActA was also identified in the peptidoglycan of extracellular bacteria growing in a chemically defined minimal medium. In this condition, ActA maintains its membrane anchoring domain and promotes efficient bacterial entry into nonphagocytic host cells. Unexpectedly, Internalin-A, which mediates entry of extracellular L. monocytogenes into eukaryotic cells, was identified at late infection times (6 h) as an abundant protein in the cell wall of intracellular bacteria. Other surface proteins covalently bound to the peptidoglycan, as Lmo0514 and Lmo2085, were detected exclusively in intracellular and extracellular bacteria, respectively. Altogether, these data provide the first insights into the changes occurring at the protein level in the L. monocytogenes cell wall as the pathogen transits from the extracellular environment to an intracytosolic lifestyle inside eukaryotic cells. Some of these changes include alterations in the relative amount and the mode of association of certain surface proteins. PMID:21846725

García-del Portillo, Francisco; Calvo, Enrique; D'Orazio, Valentina; Pucciarelli, M. Graciela

2011-01-01

454

Molecular Mechanisms Controlling GLUT4 Intracellular Retention  

Microsoft Academic Search

ABSTRACT In basal adipocytes GLUT4 is sequestered intracellularly by an insulin-reversible retention mechanism. Here we analyze the roles of three GLUT4 trafficking motifs (FQQI, TELEY and LL), providing molecular links between insulin signaling, cellular trafficking machinery and the motifs in the specialized trafficking of GLUT4. Our resultssupport a GLUT4 retention model that involves two linked intracellular cycles: one between endosomes

Vincent Blot; Timothy E. McGraw

2008-01-01

455

Stomata and pathogens  

PubMed Central

Bacteria and fungi are capable of triggering stomatal closure through pathogen-associated molecular patterns (PAMPs), which prevents penetration through these pores. Therefore, the stomata can be considered part of the plant innate immune response. Some pathogens have evolved mechanisms to evade stomatal defense. The bacterial pathogen Xanthomonas campestris pv. campestris (Xcc), which infects plants of the Brassicaceae family mainly through hydathodes, has also been reported to infect plants through stomata. A recent report shows that penetration of Xcc in Arabidopsis leaves through stomata depends on a secreted small molecule whose synthesis is under control of the rpf/diffusible signal factor (DSF) cell-to-cell signaling system, which also controls genes involved in biofilm formation and pathogenesis. The same reports shows that Arabidopsis ROS- and PAMP-activated MAP kinase 3 (MPK3) is essential for stomatal innate response. Other recent and past findings about modulation of stomatal behaviour by pathogens are also discussed. In all, these findings support the idea that PAMP-triggered stomatal closure might be a more effective and widespread barrier against phytopathogens than previously thought, which has in turn led to the evolution in pathogens of several mechanisms to evade stomatal defense. PMID:20514224

Gudesblat, Gustavo E; Torres, Pablo S

2009-01-01

456

Measuring the Progressive Realization of Human Rights Obligations: An Index of Economic and Social Rights Fulfillment  

Microsoft Academic Search

In response to an increasing demand for rigorous monitoring of state accountability in meeting their human rights obligations, a growing literature on human rights measurement has emerged. Yet there are no widely used indicators or indices of human rights obligations fulfillment. This paper proposes a methodology for an index of economic and social rights fulfillment that: uses available survey-based objective,

Sakiko Fukuda-Parr; Terra Lawson-Remer; Susan Randolph

2008-01-01

457

Hospital/Health Facilities and the Hill-Burton Obligations: A Secret from the Black Community.  

ERIC Educational Resources Information Center

Uncompensated/free care and community service obligations under the Hill-Burton Act can assist substantially in providing needed health care services to the Black community. Blacks, however, must become knowledgeable about these obligations, develop monitoring projects, and be prepared to take legal steps to bring Hill-Burton facilities into…

Rice, Mitchell F.

1986-01-01

458

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

459

45 CFR 96.14 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2014 CFR

...period for obligation and expenditure of grant funds. 96...Welfare Department of Health and Human Services...period for obligation and expenditure of grant funds. ...exist on the time for expenditure of block grant funds...maternal and child health services, and...

2014-10-01

460

45 CFR 96.14 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2011 CFR

...period for obligation and expenditure of grant funds. 96...Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES...period for obligation and expenditure of grant funds. ...exist on the time for expenditure of block grant funds...maternal and child health services, and...

2011-10-01

461

45 CFR 96.14 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2010 CFR

...period for obligation and expenditure of grant funds. 96...Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES...period for obligation and expenditure of grant funds. ...exist on the time for expenditure of block grant funds...maternal and child health services, and...

2010-10-01

462

45 CFR 96.14 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2012 CFR

...period for obligation and expenditure of grant funds. 96...Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES...period for obligation and expenditure of grant funds. ...exist on the time for expenditure of block grant funds...maternal and child health services, and...

2012-10-01

463

45 CFR 96.14 - Time period for obligation and expenditure of grant funds.  

Code of Federal Regulations, 2013 CFR

...period for obligation and expenditure of grant funds. 96...Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES...period for obligation and expenditure of grant funds. ...exist on the time for expenditure of block grant funds...maternal and child health services, and...

2013-10-01

464

26 CFR 1.453-9 - Gain or loss on disposition of installment obligations.  

Code of Federal Regulations, 2014 CFR

...20,000, 50 percent. Face value of notes 15,000 ...of obligation—excess of face value of notes over amount of...of obligation—excess of face value of notes over amount...provides for exceptions to the recognition of gain or loss in...

2014-04-01

465

28 CFR 811.6 - Duration of the obligation to register.  

Code of Federal Regulations, 2010 CFR

...false Duration of the obligation to register. 811.6 Section 811.6 Judicial...811.6 Duration of the obligation to register. (a) Lifetime registration. ...for a sex offender who is required to register for life shall end upon the sex...

2010-07-01

466

Contractual obligations and the sharing of confidential health information in sport  

Microsoft Academic Search

As an employee, a sports doctor has obligations to their employer, but also professional and widely accepted obligations of a doctor to the patient (in this case the individual team member). The conflict is evident when sports doctors are asked by an athlete to keep personal health information confidential from the coach and team management, and yet both doctor and

L Anderson

2008-01-01

467

17 CFR 290.3 - Reports with respect to proposed distribution of obligations.  

Code of Federal Regulations, 2010 CFR

The EBRD shall file with the Commission, on or prior to the date on which it sells any of its primary obligations in connection with a distribution of such obligations in the United States, a report containing the information and documents specified in Schedule A of this...

2010-04-01

468

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

469

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

470

John Locke on Obligation: Sensation, Reflection, and the Natural Duty to Consent  

Microsoft Academic Search

DISSERTATION ABSTRACT: John Locke on Obligation: Sensation, Reflection, and the Natural Duty to Consent By Emily Marie Crookston Doctor of Philosophy in Philosophy Washington University in St. Louis, 2009 Professor Larry May, Chairperson Locke's theories of moral and political obligation are instructive both in their successes and in their failures. Writing during a time in which previous assumptions were being

Emily Crookston

2009-01-01

471

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

472

Maintenance of Vacuole Integrity by Bacterial Pathogens  

PubMed Central

Many intracellular bacterial pathogens reside within a membrane-bound compartment. The biogenesis of these vacuolar compartments is complex, involving subversion of host cell secretory pathways by bacterial proteins. In recent years it has become clear that disruption of vacuole biogenesis may result in membrane rupture and escape of bacteria into the host cell cytosol. Correct modulation of the host cell cytoskeleton, signalling molecules such as small GTPases and the lipids of the vacuole membrane have all been shown to be critical in the maintenance of vacuole integrity. Increasing evidence suggests that vacuole rupture may result from aberrant mechanical forces exerted on the vacuole, possibly due to a defect in vacuole expansion. PMID:24581692

Creasey, Elizabeth A.; Isberg, Ralph R.

2014-01-01

473

An Extended Role-Based Access Control Model for Delegating Obligations  

NASA Astrophysics Data System (ADS)

The main aim of access control models is to provide means to simplify the management of the security policy, which is a fastidious and error-prone task. Supporting delegation is considered as an important mean to decentralize the administration and therefore to allow security policy to be more flexible and easier to manipulate. Our main contribution is the proposition of a unified model to the administration and delegation of obligations. Managing such delegations implies more requirements than managing traditional privileges delegation. In fact, delegating obligations may include two interpretations: the delegation of the obligation and the delegation of the responsibility related to this obligation. Therefore, it is important to deal with these two notions separately. Moreover, since delegating an obligation involves the delegation of sanctions, then the consent of the user who receives this delegation may be required in some cases. We address in this paper these requirements and we propose a formalism to deal with them.

Ben-Ghorbel-Talbi, Meriam; Cuppens, Frédéric; Cuppens-Boulahia, Nora; Bouhoula, Adel

474

Observer perceptions of moral obligations in groups with a history of victimization.  

PubMed

The authors investigated when observers assign contemporary group members moral obligations based on their group's victimization history. In Experiment 1, Americans perceived Israelis as obligated to help Sudanese genocide victims and as guiltworthy for not helping if reminded of the Holocaust and its descendants were linked to this history. In Experiment 2, participants perceived Israelis as more obligated to help and guiltworthy for not helping when the Holocaust was presented as a unique victimization event compared with when genocide was presented as pervasive. Experiments 3 and 4 replicated the effects of Experiment 1 with Cambodians as the victimized group. Experiment 5 demonstrated that participants perceived Cambodians as having more obligations under high just world threat compared with low just world threat. Perceiving victimized groups as incurring obligations is one just world restoration method of providing meaning to collective injustice. PMID:22427385

Warner, Ruth H; Branscombe, Nyla R

2012-07-01

475

The Human Fungal Pathogen Cryptococcus neoformans Escapes Macrophages by a Phagosome Emptying Mechanism That Is Inhibited by Arp2\\/3 Complex-Mediated Actin Polymerisation  

Microsoft Academic Search

The lysis of infected cells by disease-causing microorganisms is an efficient but risky strategy for disseminated infection, as it exposes the pathogen to the full repertoire of the host's immune system. Cryptococcus neoformans is a widespread fungal pathogen that causes a fatal meningitis in HIV and other immunocompromised patients. Following intracellular growth, cryptococci are able to escape their host cells

Simon A. Johnston; Robin C. May

2010-01-01

476

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

477

Francisella tularensis LVS initially activates but subsequently down-regulates intracellular signaling and cytokine secretion in mouse monocytic and human peripheral blood mononuclear cells  

Microsoft Academic Search

Monocytic cells constitute an important defense mechanism against invading pathogens by recognizing conserved pathogens components. The recognition leads to activation of intracellular pathways involving nuclear factor kappa B (NF-?B) and mitogen-activated protein kinases (MAPK), such as the c-Jun NH2-terminal kinase (JNK), and p38. We show that in vitro infection with Francisella tularensis results in activation of NF-?B, phosphorylation of p38

Max Telepnev; Igor Golovliov; Anders Sjöstedt

2005-01-01

478

Food, pathogen, signal  

PubMed Central

C.elegans, both in the wild and in the lab, live on a diet of live bacteria. The bacterial diet provides nutrients for C. elegans, but can also play a number of other roles in C. elegans physiology. Recently, we compared the effects of different bacterial diets on life history traits and gene expression. Here, we discuss our recent findings in the context of other dietary studies and highlight challenges in understanding dietary effects. For instance, since bacteria can be pathogenic it can be difficult to disentangle pathogenic from dietary effects. Here we summarize different bacterial diets used for C. elegans and how they affect the animal. PMID:24744980

MacNeil, Lesley T; Walhout, Albertha JM

2013-01-01

479

The Keystone Pathogen Hypothesis  

PubMed Central

Recent studies have highlighted the importance of the human microbiome in host health and disease. However, for the most part the mechanisms by which the microbiome mediates disease, or protection from it, remain poorly understood. The “keystone pathogen” hypothesis holds that certain low-abundance microbial pathogens can orchestrate inflammatory disease by remodelling a normally benign microbiota into a dysbiotic one. In this Opinion, we critically assess the available literature in support of this hypothesis, which may provide a novel conceptual basis for the development of targeted diagnostic and treatment modalities for complex dysbiotic diseases. PMID:22941505

Hajishengallis, George; Darveau, Richard P.; Curtis, Michael A.

2012-01-01

480

34 CFR 611.45 - Under what circumstances does the Secretary discharge a scholarship recipient's obligation to...  

Code of Federal Regulations, 2013 CFR

...does the Secretary discharge a scholarship recipient's obligation to repay...QUALITY ENHANCEMENT GRANTS PROGRAM Scholarships § 611.45 Under what circumstances...does the Secretary discharge a scholarship recipient's obligation to...

2013-07-01

481

34 CFR 611.45 - Under what circumstances does the Secretary discharge a scholarship recipient's obligation to...  

Code of Federal Regulations, 2011 CFR

...does the Secretary discharge a scholarship recipient's obligation to repay...QUALITY ENHANCEMENT GRANTS PROGRAM Scholarships § 611.45 Under what circumstances...does the Secretary discharge a scholarship recipient's obligation to...

2011-07-01

482

34 CFR 611.45 - Under what circumstances does the Secretary discharge a scholarship recipient's obligation to...  

Code of Federal Regulations, 2010 CFR

...does the Secretary discharge a scholarship recipient's obligation to repay...QUALITY ENHANCEMENT GRANTS PROGRAM Scholarships § 611.45 Under what circumstances...does the Secretary discharge a scholarship recipient's obligation to...

2010-07-01

483

34 CFR 611.45 - Under what circumstances does the Secretary discharge a scholarship recipient's obligation to...  

Code of Federal Regulations, 2014 CFR

...does the Secretary discharge a scholarship recipient's obligation to repay...QUALITY ENHANCEMENT GRANTS PROGRAM Scholarships § 611.45 Under what circumstances...does the Secretary discharge a scholarship recipient's obligation to...

2014-07-01

484

34 CFR 611.45 - Under what circumstances does the Secretary discharge a scholarship recipient's obligation to...  

Code of Federal Regulations, 2012 CFR

...does the Secretary discharge a scholarship recipient's obligation to repay...QUALITY ENHANCEMENT GRANTS PROGRAM Scholarships § 611.45 Under what circumstances...does the Secretary discharge a scholarship recipient's obligation to...

2012-07-01

485

17 CFR 255.16 - Ownership of interests in and sponsorship of issuers of certain collateralized debt obligations...  

Code of Federal Regulations, 2014 CFR

...debt obligations backed by trust-preferred securities. 255.16 Section...debt obligations backed by trust-preferred securities. (a) The prohibition...Collateral shall mean any trust preferred security or subordinated...

2014-04-01

486

17 CFR 75.16 - Ownership of interests in and sponsorship of issuers of certain collateralized debt obligations...  

Code of Federal Regulations, 2014 CFR

...debt obligations backed by trust-preferred securities. 75.16 Section 75...debt obligations backed by trust-preferred securities. (a) The prohibition...Collateral shall mean any trust preferred security or subordinated...

2014-04-01

487

5 CFR 2422.34 - What are the parties' rights and obligations when a representation proceeding is pending?  

Code of Federal Regulations, 2013 CFR

...parties' rights and obligations when a representation proceeding is pending? 2422.34...FEDERAL LABOR RELATIONS AUTHORITY REPRESENTATION PROCEEDINGS § 2422.34 What...parties' rights and obligations when a representation proceeding is pending? (a)...

2013-01-01

488

5 CFR 2422.34 - What are the parties' rights and obligations when a representation proceeding is pending?  

Code of Federal Regulations, 2014 CFR

...parties' rights and obligations when a representation proceeding is pending? 2422.34...FEDERAL LABOR RELATIONS AUTHORITY REPRESENTATION PROCEEDINGS § 2422.34 What...parties' rights and obligations when a representation proceeding is pending? (a)...

2014-01-01

489

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

Code of Federal Regulations, 2011 CFR

... What obligation does the retroceding Self-Governance Tribe have with respect...DEPARTMENT OF HEALTH AND HUMAN SERVICES TRIBAL SELF-GOVERNANCE Retrocession § 137.251. What obligation does the retroceding Self-Governance Tribe have with...

2011-10-01

490

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

Code of Federal Regulations, 2014 CFR

... What obligation does the retroceding Self-Governance Tribe have with respect...DEPARTMENT OF HEALTH AND HUMAN SERVICES TRIBAL SELF-GOVERNANCE Retrocession § 137.251. What obligation does the retroceding Self-Governance Tribe have with...

2014-10-01

491

33 CFR 96.490 - What further obligations exist for an organization if the Coast Guard terminates its authorization?  

Code of Federal Regulations, 2012 CFR

...obligations exist for an organization if the Coast Guard terminates its authorization...obligations exist for an organization if the Coast Guard terminates its authorization...organization receives authorization from the Coast Guard places it under certain...

2012-07-01

492

33 CFR 96.490 - What further obligations exist for an organization if the Coast Guard terminates its authorization?  

Code of Federal Regulations, 2010 CFR

...obligations exist for an organization if the Coast Guard terminates its authorization...obligations exist for an organization if the Coast Guard terminates its authorization...organization receives authorization from the Coast Guard places it under certain...

2010-07-01

493

33 CFR 96.490 - What further obligations exist for an organization if the Coast Guard terminates its authorization?  

Code of Federal Regulations, 2013 CFR

...obligations exist for an organization if the Coast Guard terminates its authorization...obligations exist for an organization if the Coast Guard terminates its authorization...organization receives authorization from the Coast Guard places it under certain...

2013-07-01

494

33 CFR 96.490 - What further obligations exist for an organization if the Coast Guard terminates its authorization?  

Code of Federal Regulations, 2014 CFR

...obligations exist for an organization if the Coast Guard terminates its authorization...obligations exist for an organization if the Coast Guard terminates its authorization...organization receives authorization from the Coast Guard places it under certain...

2014-07-01

495

33 CFR 96.490 - What further obligations exist for an organization if the Coast Guard terminates its authorization?  

Code of Federal Regulations, 2011 CFR

...obligations exist for an organization if the Coast Guard terminates its authorization...obligations exist for an organization if the Coast Guard terminates its authorization...organization receives authorization from the Coast Guard places it under certain...

2011-07-01

496

DISINFECTION OF EMERGING PATHOGENS  

EPA Science Inventory

There is a growing awareness of the need to control waterborne microbial pathogens. This presentation will concentate on the role of chemical inactivation, using chlorine, chloramines and ozone as a means of controlling bacterial and protozoan species. Information will be present...

497

Leafhopper viral pathogens  

Technology Transfer Automated Retrieval System (TEKTRAN)

Four newly discovered viral pathogens in leafhopper vectors of Pierce’s disease of grapes, have been shown to replicate in sharpshooter leafhoppers; the glassy-winged sharpshooter, GWSS, Homalodisca vitripennis, and Oncometopia nigricans (Hemiptera: Cicadellidae). The viruses were classified as memb...

498

PATHOGEN EQUIVALENCY COMMITTEE (PEC)  

EPA Science Inventory

The U.S. Environmental Protection Agency created the PEC in 1985 to make recommendations to EPA and State managers on the equivalency of unproven sewage sludge disinfection technologies/processes to either a Process to Significantly Reduce Pathogens (PSRP) or a Process to Further...

499

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

500

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