Note: This page contains sample records for the topic obligate intracellular bacterial from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Advances in Genetic Manipulation of Obligate Intracellular Bacterial Pathogens  

PubMed Central

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

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

2011-01-01

2

Antibody-mediated elimination of the obligate intracellular bacterial pathogen Ehrlichia chaffeensis during active infection.  

PubMed

It is generally accepted that cellular, but not humoral immunity, plays an important role in host defense against intracellular bacteria. However, studies of some of these pathogens have provided evidence that antibodies can provide immunity if present during the initiation of infection. Here, we examined immunity against infection by Ehrlichia chaffeensis, an obligate intracellular bacterium that causes human monocytic ehrlichiosis. Studies with mice have demonstrated that immunocompetent strains are resistant to persistent infection but that SCID mice become persistently and fatally infected. Transfer of immune serum or antibodies obtained from immunocompetent C57BL/6 mice to C57BL/6 scid mice provided significant although transient protection from infection. Bacterial clearance was observed when administration occurred at the time of inoculation or well after infection was established. The effect was dose dependent, occurred within 2 days, and persisted for as long as 2 weeks. Weekly serum administration prolonged the survival of susceptible mice. Although cellular immunity is required for complete bacterial clearance, the data show that antibodies can play a significant role in the elimination of this obligate intracellular bacterium during active infection and thus challenge the paradigm that humoral responses are unimportant for immunity to such organisms. PMID:10722619

Winslow, G M; Yager, E; Shilo, K; Volk, E; Reilly, A; Chu, F K

2000-04-01

3

Antibody-Mediated Elimination of the Obligate Intracellular Bacterial Pathogen Ehrlichia chaffeensis during Active Infection  

Microsoft Academic Search

It is generally accepted that cellular, but not humoral immunity, plays an important role in host defense against intracellular bacteria. However, studies of some of these pathogens have provided evidence that antibodies can provide immunity if present during the initiation of infection. Here, we examined immunity against infection by Ehrlichia chaffeensis, an obligate intracellular bacterium that causes human monocytic ehrlichiosis.

GARY M. WINSLOW; ERIC YAGER; KONSTANTIN SHILO; ERIN VOLK; ANDREW REILLY; FREDERICK K. CHU

2000-01-01

4

OspA, a Lipoprotein Antigen of the Obligate Intracellular Bacterial Pathogen Piscirickettsia salmonis  

Microsoft Academic Search

No effective recombinant vaccines are currently available for any rickettsial diseases. In this regard the first non-ribosomal DNA sequences from the obligate intracellular pathogen Piscirickettsia salmonis are presented. Genomic DNA isolated from Percoll density gradient purified P. salmonis, was used to construct an expression library in lambda ZAP II. In the absence of preexisting DNA sequence, rabbit polyclonal antiserum raised

Michael A. Kuzyk; Ján Burian; Julian C. Thornton; William W. Kay

2001-01-01

5

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.

Feldhaar, Heike; Gross, Roy

2009-01-01

6

Obligate intracellular parasites: Rickettsia prowazekii and Chlamydia trachomatis.  

PubMed

Transitions to obligate intracellular parasitism have occurred at numerous times in the evolutionary past. The genome sequences of two obligate intracellular parasites, Rickettsia prowazekii and Chlamydia trachomatis, were published last year. A comparative analysis of these two genomes has revealed examples of reductive convergent evolution, such as a massive loss of genes involved in biosynthetic functions. In addition, both genomes were found to encode transport systems for ATP and ADP, not otherwise found in bacteria. Here, we discuss adaptations to intracellular habitats by comparing the information obtained from the recently published genome sequences of R. prowazekii and C. trachomatis. PMID:10376669

Zomorodipour, A; Andersson, S G

1999-06-01

7

Metabolic Interdependence of Obligate Intracellular Bacteria and Their Insect Hosts†  

PubMed Central

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

Zientz, Evelyn; Dandekar, Thomas; Gross, Roy

2004-01-01

8

Molecular pathogenesis of the obligate intracellular bacterium Coxiella burnetii.  

PubMed

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

2013-06-24

9

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

PubMed Central

Genome evolution of bacteria is usually influenced by ecology, such that bacteria with a free-living stage have large genomes and high rates of horizontal gene transfer, while obligate intracellular bacteria have small genomes with typically low amounts of gene exchange. However, recent studies indicate that obligate intracellular species that host-switch frequently harbor agents of horizontal transfer such as mobile elements. For example, the temperate double-stranded DNA bacteriophage WO in Wolbachia persistently transfers between bacterial coinfections in the same host. Here we show that despite the phage's rampant mobility between coinfections, the prophage's genome displays features of constraint related to its intracellular niche. First, there is always at least one intact prophage WO and usually several degenerate, independently-acquired WO prophages in each Wolbachia genome. Second, while the prophage genomes are modular in composition with genes of similar function grouping together, the modules are generally not interchangeable with other unrelated phages and thus do not evolve by the Modular Theory. Third, there is an unusual core genome that strictly consists of head and baseplate genes; other gene modules are frequently deleted. Fourth, the prophage recombinases are diverse and there is no conserved integration sequence. Finally, the molecular evolutionary forces acting on prophage WO are point mutation, intragenic recombination, deletion, and purifying selection. Taken together, these analyses indicate that while lateral transfer of phage WO is pervasive between Wolbachia with occasional new gene uptake, constraints of the intracellular niche obstruct extensive mixture between WO and the global phage population. Although the Modular Theory has long been considered the paradigm of temperate bacteriophage evolution in free-living bacteria, it appears irrelevant in phages of obligate intracellular bacteria.

Kent, Bethany N.; Funkhouser, Lisa J.; Setia, Shefali; Bordenstein, Seth R.

2011-01-01

10

Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth  

PubMed Central

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

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

2012-01-01

11

Autophagy in intracellular bacterial infection.  

PubMed

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

Campoy, Emanuel; Colombo, María I

2009-03-19

12

Analysis of convergent gene transcripts in the obligate intracellular bacterium Rickettsia prowazekii.  

PubMed

Termination of transcription is an important component of bacterial gene expression. However, little is known concerning this process in the obligate intracellular pathogen and model for reductive evolution, Rickettsia prowazekii. To assess transcriptional termination in this bacterium, transcripts of convergent gene pairs, some containing predicted intrinsic terminators, were analyzed. These analyses revealed that, rather than terminating at a specific site within the intervening region between the convergent genes, most of the transcripts demonstrated either a lack of termination within this region, which generated antisense RNA, or a putative non-site-specific termination that occurred throughout the intervening sequence. Transcripts terminating at predicted intrinsic terminators, as well as at a putative Rho-dependant terminator, were also examined and found to vary based on the rickettsial host environment. These results suggest that transcriptional termination, or lack thereof, plays a role in rickettsial gene regulation. PMID:21298070

Woodard, Andrew; Wood, David O

2011-01-26

13

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.

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

14

Transient Transfection and Expression in the Obligate Intracellular Parasite Toxoplasma gondii  

Microsoft Academic Search

Toxoplasma gondii is a protozoan pathogen that produces severe disease in humans and animals. This obligate intracellular parasite provides an excellent model for the study of how such pathogens are able to invade, survive, and replicate intracellularly. DNA encoding chloramphenicol acetyltransferase was introduced into T. gondii and transiently expressed with the use of three vectors based on different Toxoplasma genes.

Dominique Soldati; John C. Boothroyd

1993-01-01

15

Maspin (SERPINB5) is an obligate intracellular serpin.  

PubMed

Maspin (SERPINB5) is a tumor suppressor lost in breast and prostate cancer whose molecular function is unknown. It is a non-inhibitory member of the clade B serpins suggested to play a role in a plethora of intracellular and extracellular settings, yet its normal cellular distribution has never been clarified. Here we investigate the distribution of maspin in non-transformed human epithelial cells. By indirect immunofluorescence, maspin has a nucleocytoplasmic distribution in breast (MCF10A) and prostate (RWPE-1) cells and, by immunoblotting and pulse-chase analyses, is neither glycosylated nor secreted. Cell surface biotinylation studies also show that maspin is not present at the cell surface. Differentiation of MCF10A cells into three-dimensional acini results in the redistribution of maspin from the nucleus to the cytoplasm but does not result in secretion. Addition of an efficient conventional signal peptide to maspin directs it into the secretory pathway and results in glycosylation but not secretion. We further show that maspin in the cytoplasm of MCF10A cells is a soluble monomeric protein that is not detectably associated with the cytoskeleton or other extractable components. Taken together, these results suggest that maspin is restricted to an intracellular, possibly nuclear, role in which it influences cell-matrix interactions indirectly. It is probably released only as a consequence of cell damage or necrosis. PMID:20123984

Teoh, Sonia S Y; Whisstock, James C; Bird, Phillip I

2010-02-01

16

A Method for Purifying Obligate Intracellular Coxiella burnetii that Employs Digitonin Lysis of Host Cells  

PubMed Central

Purification of the obligate intracellular bacterium Coxiella burnetii requires physical disruption of infected cells. Here we describe a gentle and safe digitonin lysis procedure to release C. burnetii from infected cells. The purity, yield, and infectivity of digitonin-prepped organisms are comparable to that of organisms purified using cell lysis by sonication.

Cockrell, Diane C.; Beare, Paul A.; Fischer, Elizabeth R.; Howe, Dale; Heinzen, Robert. A.

2008-01-01

17

Heterogeneity of intracellular replication of bacterial pathogens.  

PubMed

Intracellular growth of bacterial pathogens is usually measured at the whole population level, which masks potential cell-to-cell variation. More direct measurements of replication using microscopy and Flow Cytometry have revealed extensive heterogeneity among populations of intracellular bacteria. Heterogeneity could result from differential exposure to nutritional deprivation and host cell antimicrobial activities, as well as variability in production or efficacy of virulence molecules. Furthermore, bacteria have evolved specific mechanisms to generate epigenetic variation. These include unequal partitioning of proteins during cell division, genetic phase variation and activation of toxin/antitoxin systems. An important aspect of heterogeneity concerns the generation of viable, non-replicating bacteria. These are predicted to confer tolerance to host-induced stress and antibiotics, and to be sources of persistent infection. PMID:23485258

Helaine, Sophie; Holden, David W

2013-02-26

18

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

Microsoft Academic Search

Received 23 August 2004\\/Accepted 23 October 2004 We developed and applied transposon-based transformation vectors for molecular manipulation and anal- ysis 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

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

2005-01-01

19

Transient Transfection and Expression in the Obligate Intracellular Parasite Toxoplasma gondii  

NASA Astrophysics Data System (ADS)

Toxoplasma gondii is a protozoan pathogen that produces severe disease in humans and animals. This obligate intracellular parasite provides an excellent model for the study of how such pathogens are able to invade, survive, and replicate intracellularly. DNA encoding chloramphenicol acetyltransferase was introduced into T. gondii and transiently expressed with the use of three vectors based on different Toxoplasma genes. The ability to introduce genes and have them efficiently and faithfully expressed is an essential tool for understanding the structure-function relation of genes and their products.

Soldati, Dominique; Boothroyd, John C.

1993-04-01

20

Bacterial Associates of Arboreal Ants and Their Putative Functions in an Obligate AntPlant Mutualism  

Microsoft Academic Search

Bacterial communities are highly diverse and have great ecological importance. In the present study, we used an in silico analysis of terminal restriction fragments (tRF) to characterize the bacterial community of the plant ant Pseudomyrmex ferrugineus. This species is an obligate inhabitant of Acacia myrmecophytes and feeds exclusively on plant-derived food sources. Ants are the dominant insect group in tropical

Sascha Eilmus; Martin Heil

2009-01-01

21

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

PubMed Central

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

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

2004-01-01

22

An optimal method of iron starvation of the obligate intracellular pathogen, Chlamydia trachomatis.  

PubMed

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

Thompson, Christopher C; Carabeo, Rey A

2011-02-14

23

Apoptotic mimicry by an obligate intracellular parasite downregulates macrophage microbicidal activity.  

PubMed

Programmed cell death by apoptosis of unnecessary or potentially harmful cells is clearly beneficial to multicellular organisms. Proper functioning of such a program demands that the removal of dying cells proceed without an inflammatory reaction. Phosphatidylserine (PS) is one of the ligands displayed by apoptotic cells that participates in their noninflammatory removal when recognized by neighboring phagocytes. PS ligation induces the release of transforming growth factor-beta (TGF-beta), an antiinflammatory cytokine that mediates the suppression of macrophage-mediated inflammation. In Hydra vulgaris, an organism that stands at the base of metazoan evolution, the selective advantage provided by apoptosis lies in the fact that Hydra can survive recycling apoptotic cells by phagocytosis. In unicellular organisms, it has been proposed that altruistic death benefits clonal populations of yeasts and trypanosomatids. Now we show that advantageous features of the apoptotic process can operate without death as the necessary outcome. Leishmania spp are able to evade the killing activity of phagocytes and establish themselves as obligate intracellular parasites. Amastigotes, responsible for disease propagation, similar to apoptotic cells, inhibit macrophage activity by exposing PS. Exposed PS participates in amastigote internalization. Recognition of this moiety by macrophages induces TGF-beta secretion and IL-10 synthesis, inhibits NO production, and increases susceptibility to intracellular leishmanial growth. PMID:11728310

de Freitas Balanco, J M; Moreira, M E; Bonomo, A; Bozza, P T; Amarante-Mendes, G; Pirmez, C; Barcinski, M A

2001-11-27

24

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

25

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

PubMed Central

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

Corsaro, Daniele; Greub, Gilbert

2006-01-01

26

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

27

Roles of autophagy in elimination of intracellular bacterial pathogens.  

PubMed

As a fundamental intracellular catabolic process, autophagy is important and required for the elimination of protein aggregates and damaged cytosolic organelles during a variety of stress conditions. Autophagy is now being recognized as an essential component of innate immunity; i.e., the recognition, selective targeting, and elimination of microbes. Because of its crucial roles in the innate immune system, therapeutic targeting of bacteria by means of autophagy activation may prove a useful strategy to combat intracellular infections. However, important questions remain, including which molecules are critical in bacterial targeting by autophagy, and which mechanisms are involved in autophagic clearance of intracellular microbes. In this review, we discuss the roles of antibacterial autophagy in intracellular bacterial infections (Mycobacteria, Salmonella, Shigella, Listeria, and Legionella) and present recent evidence in support of molecular mechanisms driving autophagy to target bacteria and eliminate invading pathogens. PMID:23653625

Jo, Eun-Kyeong; Yuk, Jae-Min; Shin, Dong-Min; Sasakawa, Chihiro

2013-05-06

28

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

2013-09-13

29

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.

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

2013-01-01

30

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.

Mansilla Pareja, Maria Eugenia; Colombo, Maria I.

2013-01-01

31

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

Microsoft Academic Search

Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, -proteobacterium, is the primary etiologic agent of globally distributed canine monocytic ehrlichiosis. Complete genome sequencing revealed that the E. canis genome consists of a single circular chromosome of 1,315,030 bp predicted to encode 925 proteins, 40 stable RNA species, 17 putative pseudogenes, and a substantial proportion of noncoding sequence (27%). Interesting genome

K. Mavromatis; C. Kuyler Doyle; A. Lykidis; N. Ivanova; M. P. Francino; Patrick S Chain; M. Shin; Stephanie Malfatti; Frank W Larimer; A. Copeland; J. C. Detter; Miriam L Land; P. M. Richardson; X. J. Yu; D. H. Walker; J. W. McBride; N C Kyripides

2006-01-01

32

Intracellular Bacterial Biofilm-Like Pods in Urinary Tract Infections  

Microsoft Academic Search

Escherichia coli entry into the bladder is met with potent innate defenses, including neutrophil influx and epithelial exfoliation. Bacterial subversion of innate responses involves invasion into bladder superficial cells. We discovered that the intracellular bacteria matured into biofilms, creating pod-like bulges on the bladder surface. Pods contained bacteria encased in a polysaccharide-rich matrix surrounded by a protective shell of uroplakin.

Gregory G. Anderson; Joseph J. Palermo; Joel D. Schilling; Robyn Roth; John Heuser; Scott J. Hultgren

2003-01-01

33

Genomic insights into an obligate epibiotic bacterial predator: Micavibrio aeruginosavorus ARL-13  

PubMed Central

Background Although bacterial predators play important roles in the dynamics of natural microbial communities, little is known about the molecular mechanism of bacterial predation and the evolution of diverse predatory lifestyles. Results We determined the complete genome sequence of Micavibrio aeruginosavorus ARL-13, an obligate bacterial predator that feeds by "leeching" externally to its prey. Despite being an obligate predator depending on prey for replication, M. aeruginosavorus encodes almost all major metabolic pathways. However, our genome analysis suggests that there are multiple amino acids that it can neither make nor import directly from the environment, thus providing a simple explanation for its strict dependence on prey. Remarkably, despite apparent genome reduction, there is a massive expansion of genomic islands of foreign origin. At least nine genomic islands encode many genes that are likely important for Micavibrio-prey interaction such as hemolysin-related proteins. RNA-Seq analysis shows substantial transcriptome differences between the attack phase, when M. aeruginosavorus seeks its prey, and the attachment phase, when it feeds and multiplies. Housekeeping genes as well as genes involved in protein secretion were all dramatically up-regulated in the attachment phase. In contrast, genes involved in chemotaxis and flagellum biosynthesis were highly expressed in the attack phase but were shut down in the attachment phase. Our transcriptomic analysis identified additional genes likely important in Micavibrio predation, including porins, pilins and many hypothetical genes. Conclusions The findings from our phylogenomic and transcriptomic analyses shed new light on the biology and evolution of the epibiotic predatory lifestyle of M. aeruginosavorus. The analysis reported here and the availability of the complete genome sequence should catalyze future studies of this organism.

2011-01-01

34

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.

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

2009-01-01

35

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

Microsoft Academic Search

Ehrlichia chaffeensis is an obligatory intracellular bacterium which resides in an early endosome in mono- cytes. E. chaffeensis infection in a human monocyte cell line (THP1) significantly altered the transcriptional levels of 4.5% of host genes, including those coding for apoptosis inhibitors, proteins regulating cell differen- tiation, signal transduction, proinflammatory cytokines, biosynthetic and metabolic proteins, and membrane trafficking proteins. The

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

2004-01-01

36

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

Microsoft Academic Search

BACKGROUND: The ability of rickettsiae to survive in multiple eukaryotic host environments provides a good model for studying pathogen-host molecular interactions. Rickettsia typhi, the etiologic agent of murine typhus, is a strictly intracellular gram negative ?-proteobacterium, which is transmitted to humans by its arthropod vector, the oriental rat flea, Xenopsylla cheopis. Thus, R. typhi must cycle between mammalian and flea

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

2008-01-01

37

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

PubMed Central

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

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

2008-01-01

38

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.

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

2013-01-01

39

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

SciTech Connect

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

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

2006-01-01

40

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.

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

2011-01-01

41

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.

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

2012-01-01

42

Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens  

PubMed Central

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

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

2012-01-01

43

Genomic revelations of a mutualism: the pea aphid and its obligate bacterial symbiont  

Microsoft Academic Search

The symbiosis of the pea aphid Acyrthosphion pisum with the bacterium Buchnera aphidicola APS represents the best-studied insect obligate symbiosis. Here we present a refined picture of this symbiosis by linking\\u000a pre-genomic observations to new genomic data that includes the complete genomes of the eukaryotic and prokaryotic symbiotic\\u000a partners. In doing so, we address four issues central to understanding the

Shuji ShigenobuAlex; Alex C. C. Wilson

2011-01-01

44

Occurrence of Fragmented 16S rRNA in an Obligate Bacterial Endosymbiont of Paramecium caudatum  

Microsoft Academic Search

The phylogenetic position of Caedibacter caryophila, a so far noncultured killer symbiont of Paramecium caudatum, was elucidated by comparative sequence analysis of in vitro amplified 16S rRNA genes (rDNA). C. caryophila is a member of the alpha subclass of the Proteobacteria phylum. Within this subclass C. caryophila is moderately related to Holospora obtusa, which is another obligate endosymbiont of Paramecium

Nina Springer; Wolfgang Ludwig; Rudolf Amann; Helmut Josef Schmidt; Hans-Dieter Gortz; Karl-Heinz Schleifer

1993-01-01

45

Motor-driven intracellular transport powers bacterial gliding motility.  

PubMed

Protein-directed intracellular transport has not been observed in bacteria despite the existence of dynamic protein localization and a complex cytoskeleton. However, protein trafficking has clear potential uses for important cellular processes such as growth, development, chromosome segregation, and motility. Conflicting models have been proposed to explain Myxococcus xanthus motility on solid surfaces, some favoring secretion engines at the rear of cells and others evoking an unknown class of molecular motors distributed along the cell body. Through a combination of fluorescence imaging, force microscopy, and genetic manipulation, we show that membrane-bound cytoplasmic complexes consisting of motor and regulatory proteins are directionally transported down the axis of a cell at constant velocity. This intracellular motion is transmitted to the exterior of the cell and converted to traction forces on the substrate. Thus, this study demonstrates the existence of a conserved class of processive intracellular motors in bacteria and shows how these motors have been adapted to produce cell motility. PMID:21482768

Sun, Mingzhai; Wartel, Morgane; Cascales, Eric; Shaevitz, Joshua W; Mignot, Tâm

2011-04-11

46

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

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

47

Dissection of a Type I Interferon Pathway in Controlling Bacterial Intracellular Infection in Mice  

PubMed Central

Defense mechanisms against intracellular bacterial pathogens are incompletely understood. Our study characterizes a type I IFN-dependent cell-autonomous defense pathway directed against Legionella pneumophila, an intracellular model organism and frequent cause of pneumonia. We show that macrophages infected with L. pneumophila produced IFN? in a STING- and IRF3-dependent manner. Paracrine type I IFNs stimulated up-regulation of IFN-stimulated genes and a cell-autonomous defense pathway acting on replicating and non-replicating Legionella within their specialized vacuole. Our infection experiments in mice lacking receptors for type I and/or II IFNs show that type I IFNs contribute to expression of IFN-stimulated genes and to bacterial clearance as well as resistance in L. pneumophila pneumonia in addition to type II IFN. Overall, our study shows that paracrine type I IFNs mediate defense against L. pneumophila, and demonstrates a protective role of type I IFNs in in vivo infections with intracellular bacteria.

Lippmann, Juliane; Muller, Holger; Naujoks, Jan; Tabeling, Christoph; Shin, Sunny; Witzenrath, Martin; Hellwig, Katharina; Kirschning, Carsten J.; Taylor, Gregory A.; Barchet, Winfried; Bauer, Stefan; Suttorp, Norbert; Roy, Craig R.; Opitz, Bastian

2011-01-01

48

CD11c Expression Identifies a Population of Extrafollicular Antigen-Specific Splenic Plasmablasts Responsible for CD4 T-Independent Antibody Responses during Intracellular Bacterial Infection1  

PubMed Central

Although T-independent immunity is known to be generated against bacterial capsular and cell wall polysaccharides expressed by a number of bacterial pathogens, it has not been studied in depth during intracellular bacterial infections. Our previous study demonstrated that Ehrlichia muris, an obligate intracellular tick-borne pathogen, generates protective classical TI responses in CD4 T cell-deficient C57BL/6 mice. We found that E. muris T-independent immunity is accompanied by the expansion of a very large extrafollicular spleen population of CD11clow-expressing plasmablasts that exhibit characteristics of both B-1 and marginal zone B cells. The plasmablasts comprised up to 15% of the total spleen lymphocytes and ?70% of total spleen IgMhighIgDlow cells during peak infection in both wild-type and MHC class II-deficient mice. The CD11clow cells exhibited low surface expression of B220, CD19, and CD1d, high expression of CD11b, CD43, but did not express CD5. Approximately 50% of the CD11clow cells also expressed CD138. In addition to CD11b and CD11c, the plasmablasts expressed the ?1 (CD29) and ?4 (CD49d) integrins, as well as the chemokine receptor CXCR4, molecules which may play roles in localizing the B cells extrafollicular region of the spleen. During peak infection, the CD11clow cells accounted for the majority of the IgM-producing splenic B cells and nearly all of the E. muris outer membrane protein-specific IgM-secreting cells. Thus, during this intracellular bacterial infection, CD11c expression identifies a population of Ag-specific spleen plasmablasts responsible for T-independent Ab production.

Racine, Rachael; Chatterjee, Madhumouli; Winslow, Gary M.

2008-01-01

49

A bacterial-two-hybrid selection system for one-step isolation of intracellularly functional Nanobodies.  

PubMed

Camel single-domain antibody fragments or Nanobodies, are practical in a wide range of applications. Their unique biochemical and biophysical properties permit an intracellular expression and antigen targeting. The availability of an efficient intracellular selection step would immediately identify the best intracellularly performing functional antibody fragments. Therefore, we assessed a bacterial-two-hybrid system to retrieve such Nanobodies. With GFP as an antigen we demonstrate that antigen-specific Nanobodies of sub-micromolar affinity and stability above 30 kJ/mol, at a titer of 10(-4) can be retrieved in a single-step selection. This was further proven practically by the successful recovery from an 'immune' library of multiple stable, antigen-specific Nanobodies of good affinity for HIV-1 integrase or nucleoside hydrolase. The sequence diversity, intrinsic domain stability, antigen-specificity and affinity of these binders compare favorably to those that were retrieved in parallel by phage display pannings. PMID:22583807

Pellis, Mireille; Pardon, Els; Zolghadr, Kourosh; Rothbauer, Ulrich; Vincke, Cécile; Kinne, Joerg; Dierynck, Inge; Hertogs, Kurt; Leonhardt, Heinrich; Messens, Joris; Muyldermans, Serge; Conrath, Katja

2012-05-11

50

Intracellular magneto-spatial organization of magnetic organelles inside intact bacterial cells.  

PubMed

Magnetotactic bacteria naturally produce magnetosomes, i.e., biological membrane bound nanomagnets, at ambient conditions. It is important to understand simultaneously the possible size variations and the magnetic behavior of nano-magnets inside intact bacterial cells for both applicational purposes as well as to enhance the basic understanding of biomineralization leading to intracellular nano-magnet synthesis. In this work, we utilize High-resolution Transmission Electron Microscopy and Near-field Scanning Optical Microscopy based measurements on intact non-fixed single cells to rigorously and quantitatively understand the intra-cellular magneto-spatial distribution of nano-magnets synthesized by Magnetospirillum gryphiswaldense. We demonstrate that it is possible to measure the relative magnetic moments along the intracellular magnetosomal chains for intact and non-fixed bacterial cells. Using our in vivo measurements on several single cells, we report that magnetic behavior of intracellular nano-magnets synthesized by magnetotactic bacteria depend on their relative location in the magnetosomal chains. Our work opens promising avenues in the direction of measuring the magnetic behavior of nano-magnets inside living systems by utilizing an operationally straight-forward approach. PMID:21870462

Naresh, Mohit; Sharma, Manish; Mittal, Aditya

2011-08-01

51

Detection of intracellular bacterial communities in a child with Escherichia coli recurrent urinary tract infections.  

PubMed

The formation of intracellular bacterial communities (IBC) has been proposed as a new pathogenic model for urinary tract infections. Scarce reports describe this phenomenon in humans. We describe the presence of IBC in uroepithelial cells of a child with recurrent urinary infections. Urine specimen was collected from a child with Escherichia coli UTI and analyzed by light and confocal laser scanning microscopy (CLSM). The capability of this strain to produce intracellular infection in bladder tissue was confirmed in mice models. Escherichia coli phylogenetic group, presence of virulence factors genes, and its multiple locus sequence type were determined. CLSM showed large collections of morphologically coccoid and rod bacteria in eukaryotic cells cytoplasm, even seemingly protruding from the cells. Escherichia coli EC7U, ST3626, harbored type 1, P, and S/F1C fimbriae and K1 capsule genes. In this report, we confirm the presence of IBC in children with UTI, as it has been described before in women. PMID:23733378

Robino, Luciana; Scavone, Paola; Araujo, Lucia; Algorta, Gabriela; Zunino, Pablo; Vignoli, Rafael

2013-06-26

52

The Salmonella effector AvrA mediates bacterial intracellular survival during infection in vivo  

PubMed Central

SUMMARY The enteric pathogen Salmonella typhimurium secretes the preformed AvrA effector protein into host cells. This acetyltransferase has been shown to modulate mammalian intestinal immune and survival responses by inhibition of JNK MAPK. To study the role of this effector in natural enteric infection, we used a mouse model to compare wild type Salmonella typhimurium to an isogenic AvrA null Salmonella mutant. Salmonella lacking AvrA induced increased intestinal inflammation, more intense systemic cytokine responses, and increased apoptosis in epithelial cells. Increased apoptosis was also observed in extra epithelial macrophages. AvrA null infected mice consistently showed higher bacterial burden within mucosal lymphoid tissues, spleen and liver by 5 days post infection, which indicated a more severe clinical course. To study the molecular mechanisms involved, recombinant adenoviruses expressing AvrA or mutant AvrA proteins were constructed, which showed appropriate expression and mediated the expected inhibition of JNK signaling. Cultured epithelial cells and macrophages transduced with AvrA expressing adenovirus were protected from apoptosis induced by exogenous stimuli. In conclusion, the results demonstrated that Salmonella AvrA modulates survival of infected macrophages likely via JNK suppression, and prevents macrophage death and rapid bacterial dissemination. AvrA suppression of apoptosis in infected macrophages may allow for establishment of a stable intracellular niche typical of intracellular pathogens.

Wu, Huixia; Jones, Rheinallt M.; Neish, Andrew S.

2011-01-01

53

Regulation of Transcription in a Reduced Bacterial Genome: Nutrient-Provisioning Genes of the Obligate Symbiont Buchnera aphidicola  

Microsoft Academic Search

Buchnera aphidicola, the obligate symbiont of aphids, has an extremely reduced genome, of which about 10% is devoted to the biosynthesis of essential amino acids needed by its hosts. Most regulatory genes for these pathways are absent, raising the question of whether and how transcription of these genes responds to the major shifts in dietary amino acid content encountered by

Nancy A. Moran; Helen E. Dunbar; Jennifer L. Wilcox

2005-01-01

54

Francisella tularensis Induces Cytopathogenicity and Apoptosis in Murine Macrophages via a Mechanism That Requires Intracellular Bacterial Multiplication  

Microsoft Academic Search

The murine macrophage-like cell line J774.A1 ingests and allows intracellular growth of Francisella tularen- sis. We demonstrate that, after 24 h of infection, a pronounced cytopathogenicity resulted and the J774 cells were undergoing apoptosis. Despite this host cell apoptosis, no decrease in bacterial numbers was observed. When internalization of bacteria was prevented or intracellularly located F. tularensis bacteria were eradicated

XIN-HE LAI; IGOR GOLOVLIOV; ANDERS SJOSTEDT

2001-01-01

55

Induction of Nod1 and Nod2 Intracellular Pattern Recognition Receptors in Murine Osteoblasts following Bacterial Challenge  

PubMed Central

Osteoblasts produce an array of immune molecules following bacterial challenge that could recruit leukocytes to sites of infection and promote inflammation during bone diseases, such as osteomyelitis. Recent studies from our laboratory have shed light on the mechanisms by which this cell type can perceive and respond to bacteria by demonstrating the functional expression of members of the Toll-like family of cell surface pattern recognition receptors by osteoblasts. However, we have shown that bacterial components fail to elicit immune responses comparable with those seen following challenge with the intracellular pathogens salmonellae and Staphylococcus aureus. In the present study, we show that UV-killed bacteria and invasion-defective bacterial strains elicit significantly less inflammatory cytokine production than their viable wild-type counterparts. Importantly, we demonstrate that murine osteoblasts express the novel intracellular pattern recognition receptors Nod1 and Nod2. Levels of mRNA encoding Nod molecules and protein expression are significantly and differentially increased from low basal levels following exposure to these disparate bacterial pathogens. In addition, we have shown that osteoblasts express Rip2 kinase, a critical downstream effector molecule for Nod signaling. Furthermore, to begin to establish the functional nature of Nod expression, we show that a specific ligand for Nod proteins can significantly augment immune molecule production by osteoblasts exposed to either UV-inactivated bacteria or bacterial lipopolysaccharide. As such, the presence of Nod proteins in osteoblasts could represent an important mechanism by which this cell type responds to intracellular bacterial pathogens of bone.

Marriott, Ian; Rati, Dana M.; McCall, Samuel H.; Tranguch, Susanne L.

2005-01-01

56

Antigen-driven Induction of Polyreactive IgM during Intracellular Bacterial Infection  

PubMed Central

Polyreactivity is well known as a property of natural IgM produced by B-1 cells. We demonstrate that polyreactive IgM is also generated during infection of mice with Ehrlichia muris, a tick-borne intracellular bacterial pathogen. The polyreactive IgM bound self and foreign antigens, including single- and double-stranded DNA, insulin, thyroglobulin, lipopolysaccharide, influenza virus, and Borrelia burgdorferi. Production of polyreactive IgM during infection was antigen-driven, not due to polyclonal B cell activation, as the majority of polyreactive IgM recognized ehrlichial antigen(s), including an immunodominant outer membrane protein-19 (OMP-19). Monoclonal polyreactive IgM derived from T cell-independent spleen plasmablasts, which was germline-encoded, also bound cytoplasmic and nuclear antigens in HEp-2 cells. Polyreactive IgM protected immunocompromised mice against lethal bacterial challenge infection. Serum from human ehrlichiosis patients also contained poly- and self-reactive IgM. We propose that polyreactivity increases IgM efficacy during infection, but may also exacerbate or mollify the response to foreign and self antigens.

Jones, Derek D.; DeIulio, Gregory A.; Winslow, Gary M.

2012-01-01

57

Genome sequence of Blochmannia pennsylvanicus indicates parallel evolutionary trends among bacterial mutualists of insects  

Microsoft Academic Search

The distinct lifestyle of obligately intracellular bacteria can alter fundamental forces that drive and constrain genome change. In this study, sequencing the 792-kb genome of Blochmannia pennsylvanicus, an obligate endosymbiont of Camponotus pennsylvanicus, enabled us to trace evolutionary changes that occurred in the context of a bacterial-ant association. Comparison to the genome of Blochmannia floridanus reveals differential loss of genes

Patrick H. Degnan; Adam B. Lazarus; Jennifer J. Wernegreen

2005-01-01

58

Correlations Between Bacterial Ecology and Mobile DNA  

PubMed Central

Several factors can affect the density of mobile DNA in bacterial genomes including rates of exposure to novel gene pools, recombination, and reductive evolution. These traits are difficult to measure across a broad range of bacterial species, but the ecological niches occupied by an organism provide some indication of the relative magnitude of these forces. Here, by analyzing 384 bacterial genomes assigned to three ecological categories (obligate intracellular, facultative intracellular, and extracellular), we address two, related questions: How does the density of mobile DNA vary across the Bacteria? And is there a statistically supported relationship between ecological niche and mobile element gene density? We report three findings. First, the fraction of mobile element genes in bacterial genomes ranges from 0 to 21% and decreases significantly: facultative intracellular > extracellular > obligate intracellular bacteria. Results further show that the obligate intracellular bacteria that host switch have a higher mobile DNA gene density than the obligate intracellular bacteria that are vertically transmitted. Second, while bacteria from the three ecological niches differ in their average mobile DNA contents, the ranges of mobile DNA found in each category overlap a surprising extent, suggesting bacteria with different lifestyles can tolerate similar amounts of mobile DNA. Third, mobile DNA gene densities increase with genome size across the entire dataset, and the significance of this correlation is dependent on the obligate intracellular bacteria. Further, mobile DNA gene densities do not correlate with evolutionary relationships in a 16S rDNA phylogeny. These findings statistically support a compelling link between mobile element evolution and bacterial ecology.

Newton, Irene L. G.

2010-01-01

59

Institutional obligation  

SciTech Connect

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

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

1988-01-01

60

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

61

Hypertonic saline enhances host response to bacterial challenge by augmenting neutrophil intracellular Superoxide formation  

Microsoft Academic Search

Conclusions  HTS significantly enhances neutrophil-mediated intracellular killing of bacteria. This provides further evidence of the beneficial\\u000a effects of hypertonic resuscitation in the critically ill patient.

C. J. Shields; J. H. Wang; D. C. Winter; W. O. Kirwan; H. P. Redmond

2002-01-01

62

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

PubMed

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 ion-paired with the anionic AOT surfactant to obtain a hydrophobic complex (GEN-AOT) that was formulated as a particulated material either by the precipitation with a compressed antisolvent (PCA) method or by encapsulation into poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs). The micronization of GEN-AOT by PCA yielded a particulated material with a higher surface area than the non-precipitated complex, while PLGA NPs within a size range of 250-330 nm and a sustained release of the drug over 70 days were obtained by preparing the NPs using the emulsion solvent evaporation method. For the first time, GEN encapsulation efficiency values of ?100% were achieved for the different NP formulations with no signs of interaction between the drug and the polymer. Finally, in vitro studies against the intracellular bacteria Brucella melitensis, used as a model of intracellular pathogen, demonstrated that the bactericidal activity of GEN was unmodified after ion-pairing, precipitation or encapsulation into NPs. These results encourage their use for treatment for infections caused by GEN-sensitive intracellular bacteria. PMID:21115143

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

2010-11-27

63

Molecular mechanisms of cell-cell spread of intracellular bacterial pathogens  

PubMed Central

Several bacterial pathogens, including Listeria monocytogenes, Shigella flexneri and Rickettsia spp., have evolved mechanisms to actively spread within human tissues. Spreading is initiated by the pathogen-induced recruitment of host filamentous (F)-actin. F-actin forms a tail behind the microbe, propelling it through the cytoplasm. The motile pathogen then encounters the host plasma membrane, forming a bacterium-containing protrusion that is engulfed by an adjacent cell. Over the past two decades, much progress has been made in elucidating mechanisms of F-actin tail formation. Listeria and Shigella produce tails of branched actin filaments by subverting the host Arp2/3 complex. By contrast, Rickettsia forms tails with linear actin filaments through a bacterial mimic of eukaryotic formins. Compared with F-actin tail formation, mechanisms controlling bacterial protrusions are less well understood. However, recent findings have highlighted the importance of pathogen manipulation of host cell–cell junctions in spread. Listeria produces a soluble protein that enhances bacterial protrusions by perturbing tight junctions. Shigella protrusions are engulfed through a clathrin-mediated pathway at ‘tricellular junctions’—specialized membrane regions at the intersection of three epithelial cells. This review summarizes key past findings in pathogen spread, and focuses on recent developments in actin-based motility and the formation and internalization of bacterial protrusions.

Ireton, Keith

2013-01-01

64

Polysaccharide Capsule and Sialic Acid-Mediated Regulation Promote Biofilm-Like Intracellular Bacterial Communities during Cystitis ?  

PubMed Central

Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections (UTIs). A murine UTI model has revealed an infection cascade whereby UPEC undergoes cycles of invasion of the bladder epithelium, intracellular proliferation in polysaccharide-containing biofilm-like masses called intracellular bacterial communities (IBC), and then dispersal into the bladder lumen to initiate further rounds of epithelial colonization and invasion. We predicted that the UPEC K1 polysaccharide capsule is a key constituent of the IBC matrix. Compared to prototypic E. coli K1 strain UTI89, a capsule assembly mutant had a fitness defect in functionally TLR4+ and TLR4? mice, suggesting a protective role of capsule in inflamed and noninflamed hosts. K1 capsule assembly and synthesis mutants had dramatically reduced IBC formation, demonstrating the common requirement for K1 polysaccharide in IBC development. The capsule assembly mutant appeared dispersed in the cytoplasm of the bladder epithelial cells and failed to undergo high-density intracellular replication during later stages of infection, when the wild-type strain continued to form serial generations of IBC. Deletion of the sialic acid regulator gene nanR partially restored IBC formation in the capsule assembly mutant. These data suggest that capsule is necessary for efficient IBC formation and that aberrant sialic acid accumulation, resulting from disruption of K1 capsule assembly, produces a NanR-mediated defect in intracellular proliferation and IBC development. Together, these data demonstrate the complex but important roles of UPEC polysaccharide encapsulation and sialic acid signaling in multiple stages of UTI pathogenesis.

Anderson, Gregory G.; Goller, Carlos C.; Justice, Sheryl; Hultgren, Scott J.; Seed, Patrick C.

2010-01-01

65

Bacterial Community Morphogenesis Is Intimately Linked to the Intracellular Redox State  

PubMed Central

Many microbial species form multicellular structures comprising elaborate wrinkles and concentric rings, yet the rules governing their architecture are poorly understood. The opportunistic pathogen Pseudomonas aeruginosa produces phenazines, small molecules that act as alternate electron acceptors to oxygen and nitrate to oxidize the intracellular redox state and that influence biofilm morphogenesis. Here, we show that the depth occupied by cells within colony biofilms correlates well with electron acceptor availability. Perturbations in the environmental provision, endogenous production, and utilization of electron acceptors affect colony development in a manner consistent with redox control. Intracellular NADH levels peak before the induction of colony wrinkling. These results suggest that redox imbalance is a major factor driving the morphogenesis of P. aeruginosa biofilms and that wrinkling itself is an adaptation that maximizes oxygen accessibility and thereby supports metabolic homeostasis. This type of redox-driven morphological change is reminiscent of developmental processes that occur in metazoans.

Okegbe, Chinweike; Price-Whelan, Alexa; Sakhtah, Hassan; Hunter, Ryan C.; Newman, Dianne K.

2013-01-01

66

Bacterial community morphogenesis is intimately linked to the intracellular redox state.  

PubMed

Many microbial species form multicellular structures comprising elaborate wrinkles and concentric rings, yet the rules governing their architecture are poorly understood. The opportunistic pathogen Pseudomonas aeruginosa produces phenazines, small molecules that act as alternate electron acceptors to oxygen and nitrate to oxidize the intracellular redox state and that influence biofilm morphogenesis. Here, we show that the depth occupied by cells within colony biofilms correlates well with electron acceptor availability. Perturbations in the environmental provision, endogenous production, and utilization of electron acceptors affect colony development in a manner consistent with redox control. Intracellular NADH levels peak before the induction of colony wrinkling. These results suggest that redox imbalance is a major factor driving the morphogenesis of P. aeruginosa biofilms and that wrinkling itself is an adaptation that maximizes oxygen accessibility and thereby supports metabolic homeostasis. This type of redox-driven morphological change is reminiscent of developmental processes that occur in metazoans. PMID:23292774

Dietrich, Lars E P; Okegbe, Chinweike; Price-Whelan, Alexa; Sakhtah, Hassan; Hunter, Ryan C; Newman, Dianne K

2013-01-04

67

Modulation of neutrophil superoxide response and intracellular diacylglyceride levels by the bacterial pigment pyocyanin.  

PubMed Central

Low concentrations of pyocyanin are reported to enhance superoxide production by human neutrophils exposed to various stimuli, yet the mechanism remains unknown. Using lucigenin-enhanced chemiluminescence, we examined the kinetics of the neutrophil superoxide response in the presence of pyocyanin. At all concentrations (12.5 to 200 microM), pyocyanin decreased the peak superoxide response while prolonging the duration of the response. The prolonged response may be associated with an observed increase in intracellular diacylglyceride levels due to pyocyanin exposure.

Muller, M; Sorrell, T C

1997-01-01

68

IgM Production by Bone Marrow Plasmablasts Contributes to Long-Term Protection against Intracellular Bacterial Infection  

PubMed Central

IgM responses are well known to occur early postinfection and tend to be short-lived, which has suggested that this Ig does not significantly contribute to long-term immunity. In this study, we demonstrate that chronic infection with the intracellular bacterium Ehrlichia muris elicits a protective, long-term IgM response. Moreover, we identified a population of CD138highIgMhigh B cells responsible for Ag-specific IgM production in the bone marrow. The IgM-secreting cells, which exhibited characteristics of both plasmablasts and plasma cells, contributed to protection against fatal ehrlichial challenge. Mice deficient in activation-induced cytidine deaminase, which produce only IgM, were protected against fatal ehrlichial challenge infection. The IgM-secreting cells that we have identified were maintained in the bone marrow in the absence of chronic infection, as antibiotic-treated mice remained protected against challenge infection. Our studies identify a cell population that is responsible for the IgM production in the bone marrow, and they highlight a novel role for IgM in the maintenance of long-term immunity during intracellular bacterial infection.

Racine, Rachael; McLaughlin, Maura; Jones, Derek D.; Wittmer, Susan T.; MacNamara, Katherine C.; Woodland, David L.; Winslow, Gary M.

2011-01-01

69

Drug Effects on Intracellular Mycobacteria Determined by Mass Spectrometric Analysis of the Na 1 toK 1 Ratios of Individual Bacterial Organisms  

Microsoft Academic Search

The successful establishment of a drug screening system for intracellular cultivable and noncultivable mycobacteria based on the mass spectrometric determination of bacterial viability is described. To compare drug efficacies on intra- and extracellular mycobacteria, the mycobacteria were subjected to drug treatment either after phagocytosis by the mouse macrophage cell line RAW 264.7 or in cell-free medium. After reiso- lation, their

MONIKA WIESE; ANDULRICH SEYDEL

1996-01-01

70

Quorum sensing-controlled buoyancy through gas vesicles: Intracellular bacterial microcompartments for environmental adaptation  

PubMed Central

Gas vesicles are gas-filled microcompartments produced by many cyanobacteria and haloarchaea to regulate buoyancy and control positioning in the water column. Recently we identified the first case of gas vesicle production by a member of the Enterobacteriaceae, Serratia sp ATCC39006. Gas vesicle production enabled colonisation of the air-liquid interface and was positively regulated in low-oxygen conditions, suggesting development of these intracellular organelles is an adpative mechanism facilitating migration to the water surface. Vesicle production was also regulated by the intercellular communication molecule N?butanoyl-L?homoserine lactone (BHL) showing that gas vesicle production is controlled at the population level, through quorum sensing, with BHL acting as a morphogen. Gas vesicle production was also reciprocally regulated with flagella-driven swarming motility by the global regulatory protein RsmA, suggesting a fork in the regulatory pathway that controls induction of these distinct modes of mobility. Here we discuss these findings in the context of the interesting physiology of Serratia 39006 and highlight future prospects for gas vesicle research in this highly tractable strain.

Ramsay, Joshua P.

2012-01-01

71

A dominant function of CCaMK in intracellular accommodation of bacterial and fungal endosymbionts  

PubMed Central

In legumes, Ca2+/calmodulin-dependent protein kinase (CCaMK) is a component of the common symbiosis genes that are required for both root nodule (RN) and arbuscular mycorrhiza (AM) symbioses and is thought to be a decoder of Ca2+ spiking, one of the earliest cellular responses to microbial signals. A gain-of-function mutation of CCaMK has been shown to induce spontaneous nodulation without rhizobia, but the significance of CCaMK activation in bacterial and/or fungal infection processes is not fully understood. Here we show that a gain-of-function CCaMKT265D suppresses loss-of-function mutations of common symbiosis genes required for the generation of Ca2+ spiking, not only for nodule organogenesis but also for successful infection of rhizobia and AM fungi, demonstrating that the common symbiosis genes upstream of Ca2+ spiking are required solely to activate CCaMK. In RN symbiosis, however, CCaMKT265D induced nodule organogenesis, but not rhizobial infection, on Nod factor receptor (NFRs) mutants. We propose a model of symbiotic signaling in host legume plants, in which CCaMK plays a key role in the coordinated induction of infection thread formation and nodule organogenesis.

Hayashi, Teruyuki; Banba, Mari; Shimoda, Yoshikazu; Kouchi, Hiroshi; Hayashi, Makoto; Imaizumi-Anraku, Haruko

2010-01-01

72

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.

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

2004-01-01

73

Inhibition of intracellular bacterial replication in fibroblasts is dependent on the perforin-like protein (perforin-2) encoded by macrophage-expressed gene 1.  

PubMed

Fibroblasts are known to eliminate intracellular bacteria, but the lethal hit of the bactericidal mechanism has not been defined. We show that primary embryonic and established fibroblasts can be induced by interferons or by intracellular bacterial infection to express a perforin-like mRNA previously described as macrophage-expressed gene 1 (Mpeg1). The presence and level of the perforin-like mRNA correlate with the ability of primary mouse embryonic fibroblasts (MEF) to eliminate intracellular bacteria. In addition, siRNA knockdown of the perforin-like molecule abolishes bactericidal activity and allows intracellular bacterial replication. Complementation of MEF in which the endogenous perforin-like molecule has been knocked down with a red fluorescent protein-tagged version restores bactericidal activity. The perforin-like molecule has broad bactericidal specificity for pathogenic and non-pathogenic bacteria, including Gram-positive and -negative, and acid fast bacteria. The perforin-like molecule renders previously lysozyme-resistant bacteria sensitive to lysis by lysozyme suggesting physical damage of the outer cell wall by the perforin-like protein. MEF damage cell walls of intracellular bacteria by insertion, polymerization, and pore formation of the perforin-like protein, analogous to pore formers of complement and perforin-1 of cytolytic lymphocytes. We propose the name perforin-2. PMID:23257510

McCormack, Ryan; de Armas, Lesley R; Shiratsuchi, Motoaki; Ramos, Jahir E; Podack, Eckhard R

2012-12-15

74

Unprecedented loss of ammonia assimilation capability in a urease-encoding bacterial mutualist  

Microsoft Academic Search

BACKGROUND: Blochmannia are obligately intracellular bacterial mutualists of ants of the tribe Camponotini. Blochmannia perform key nutritional functions for the host, including synthesis of several essential amino acids. We used Illumina technology to sequence the genome of Blochmannia associated with Camponotus vafer. RESULTS: Although Blochmannia vafer retains many nutritional functions, it is missing glutamine synthetase (glnA), a component of the

Laura E Williams; Jennifer J Wernegreen

2010-01-01

75

The microRNA miR29 controls innate and adaptive immune responses to intracellular bacterial infection by targeting interferon-?  

Microsoft Academic Search

Interferon-? (IFN-?) has a critical role in immune responses to intracellular bacterial infection. MicroRNAs (miRNAs) are important in the regulation of innate and adaptive immunity. However, whether miRNAs can directly target IFN-? and regulate IFN-? production post-transcriptionally remains unknown. Here we show that infection of mice with Listeria monocytogenes or Mycobacterium bovis bacillus Calmette-Guérin (BCG) downregulated miR-29 expression in IFN-?-producing

Feng Ma; Sheng Xu; Xingguang Liu; Qian Zhang; Xiongfei Xu; Mofang Liu; Minmin Hua; Nan Li; Hangping Yao; Xuetao Cao

2011-01-01

76

Different host defences are required to protect mice from primary systemic vs pulmonary infection with the facultative intracellular bacterial pathogen, Francisella tularensis LVS  

Microsoft Academic Search

Francisella tularensis is a zoonotic, facultative intracellular bacterial pathogen capable of initiating infection, tularemia, via multiple routes including dermal micro-abrasions and inhalation. Mouse models of systemically-initiated infection with F. tularensis LVS have been used extensively to reveal potential host defence mechanisms against the pathogen. Such studies have demonstrated the critical need for neutrophils and interferon-gamma (IFN-?) to combat the early

J. Wayne Conlan; Rhonda KuoLee; Hua Shen; Ann Webb

2002-01-01

77

Type III Secretion, Contact-dependent Model for the Intracellular Development of Chlamydia  

Microsoft Academic Search

The medically significant genus Chlamydia is a class of obligate intracellular bacterial pathogens that replicate within vacuoles in host eukaryotic cells termed inclusions.\\u000a Chlamydia's developmental cycle involves two forms; an infectious extracellular form, known as an elementary body (EB), and a non-infectious\\u000a form, known as the reticulate body (RB), that replicates inside the vacuoles of the host cells. The RB

D. P. Wilson; P. Timms; D. L. S. Mcelwain; P. M. Bavoil

2006-01-01

78

Democracy and Political Obligation  

Microsoft Academic Search

The public life of political servants is characterized by other duties and obligations than private life. Conflicts can even arise between a person's public and private duties. The central point of this paper is to examine whether this difference of duties can be regarded as an effect of different forms of obligation. Can we speak of a particular form of

Herman van Erp

79

Abortion and Parental Obligation  

Microsoft Academic Search

Although it has received comparatively little attention in the literature, the question of what exactly grounds a parent's obligation to his or her offspring is of central importance to the abortion debate. This essay argues that the true ground of such obligations lies in the biological bond that exists between parents and children, a bond that is forged at conception

Andrew J. Peach

80

The Costanzo obligation  

Microsoft Academic Search

National administrative authorities are obliged to leave provisions of national law unapplied when these are incompatible with EU law. Irrespective of their position and powers under national law, national administrative authorities are supposed to comply with this so-called ‘Costanzo obligation’ as established by the Court of Justice. This raises questions of both European Union law and national constitutional law, particularly

M. J. M. Verhoeven

2011-01-01

81

A Bacterial Indole3-acetyl-L-aspartic Acid Hydrolase Inhibits Mung Bean ( Vigna radiata L.) Seed Germination Through Arginine-rich Intracellular Delivery  

Microsoft Academic Search

Indole-3-acetyl-L-aspartic acid (IAA-Asp) is a natural product in many plant species and plays many important roles in auxin\\u000a metabolism and plant physiology. IAA-Asp hydrolysis activity is, therefore, believed to affect plant physiology through changes\\u000a in IAA metabolism in plants. We applied a newly discovered technique, arginine-rich intracellular delivery (AID), to deliver\\u000a a bacterial IAA-Asp hydrolase into cells of mung bean

Kevin Liu; Han-Jung Lee; Sio San Leong; Chen-Lun Liu; Jyh-Ching Chou

2007-01-01

82

Complete Bacteriophage Transfer in a Bacterial Endosymbiont (Wolbachia) Determined by Targeted Genome Capture  

PubMed Central

Bacteriophage flux can cause the majority of genetic diversity in free-living bacteria. This tenet of bacterial genome evolution generally does not extend to obligate intracellular bacteria owing to their reduced contact with other microbes and a predominance of gene deletion over gene transfer. However, recent studies suggest intracellular coinfections in the same host can facilitate exchange of mobile elements between obligate intracellular bacteria—a means by which these bacteria can partially mitigate the reductive forces of the intracellular lifestyle. To test whether bacteriophages transfer as single genes or larger regions between coinfections, we sequenced the genome of the obligate intracellular Wolbachia strain wVitB from the parasitic wasp Nasonia vitripennis and compared it against the prophage sequences of the divergent wVitA coinfection. We applied, for the first time, a targeted sequence capture array to specifically trap the symbiont's DNA from a heterogeneous mixture of eukaryotic, bacterial, and viral DNA. The tiled array successfully captured the genome with 98.3% efficiency. Examination of the genome sequence revealed the largest transfer of bacteriophage and flanking genes (52.2 kb) to date between two obligate intracellular coinfections. The mobile element transfer occurred in the recent evolutionary past based on the 99.9% average nucleotide identity of the phage sequences between the two strains. In addition to discovering an evolutionary recent and large-scale horizontal phage transfer between coinfecting obligate intracellular bacteria, we demonstrate that “targeted genome capture” can enrich target DNA to alleviate the problem of isolating symbiotic microbes that are difficult to culture or purify from the conglomerate of organisms inside eukaryotes.

Kent, Bethany N.; Salichos, Leonidas; Gibbons, John G.; Rokas, Antonis; Newton, Irene L. G.; Clark, Michael E.; Bordenstein, Seth R.

2011-01-01

83

High-Affinity Zn2+ Uptake System ZnuABC Is Required for Bacterial Zinc Homeostasis in Intracellular Environments and Contributes to the Virulence of Salmonella enterica?  

PubMed Central

To investigate the relevance of zinc in host-pathogen interactions, we have constructed Salmonella enterica mutant strains in which the znuA gene, which encodes the periplasmic component of the ZnuABC high-affinity Zn2+ transporter, was deleted. This mutation does not alter the ability of Salmonella to grow in rich media but drastically reduces its ability to multiply in media deprived of zinc. In agreement with this phenotype, ZnuA accumulates only in bacteria cultivated in environments poor in zinc. In spite of the nearly millimolar intracellular concentration of zinc, we have found that znuA is highly expressed in intracellular salmonellae recovered either from cultivated cells or from the spleens of infected mice. We have also observed that znuA mutants are impaired in their ability to grow in Caco-2 epithelial cells and that bacteria starved for zinc display decreased ability to multiply in phagocytes. A dramatic reduction in the pathogenicity of the znuA mutants was observed in Salmonella-susceptible (BALB/c) or Salmonella-resistant (DBA-2) mice infected intraperitoneally or orally. This study shows that the amount of free metals available for bacterial growth within the infected animal is limited, despite the apparent elevated concentration of free metals within cells and in plasma and suggests that Salmonella exploits the ZnuABC zinc transporter to maximize zinc availability in such conditions. These results shed new light on the complex functions of zinc in vertebrate and bacterial physiology and pave the way for a better comprehension of pathogenic mechanisms in Salmonella infections.

Ammendola, Serena; Pasquali, Paolo; Pistoia, Claudia; Petrucci, Paola; Petrarca, Patrizia; Rotilio, Giuseppe; Battistoni, Andrea

2007-01-01

84

Glucose metabolism in Legionella pneumophila: dependence on the Entner-Doudoroff pathway and connection with intracellular bacterial growth.  

PubMed

Glucose metabolism in Legionella pneumophila was studied by focusing on the Entner-Doudoroff (ED) pathway with a combined genetic and biochemical approach. The bacterium utilized exogenous glucose for synthesis of acid-insoluble cell components but manifested no discernible increase in the growth rate. Assays with permeabilized cell preparations revealed the activities of three enzymes involved in the pathway, i.e., glucokinase, phosphogluconate dehydratase, and 2-dehydro-3-deoxy-phosphogluconate aldolase, presumed to be encoded by the glk, edd, and eda genes, respectively. Gene-disrupted mutants for the three genes and the ywtG gene encoding a putative sugar transporter were devoid of the ability to metabolize exogenous glucose, indicating that the pathway is almost exclusively responsible for glucose metabolism and that the ywtG gene product is the glucose transporter. It was also established that these four genes formed part of an operon in which the gene order was edd-glk-eda-ywtG, as predicted by genomic information. Intriguingly, while the mutants exhibited no appreciable change in growth characteristics in vitro, they were defective in multiplication within eukaryotic cells, strongly indicating that the ED pathway must be functional for the intracellular growth of the bacterium to occur. Curiously, while the deficient glucose metabolism of the ywtG mutant was successfully complemented by the ywtG(+) gene supplied in trans via plasmid, its defect in intracellular growth was not. However, the latter defect was also manifested in wild-type cells when a plasmid carrying the mutant ywtG gene was introduced. This phenomenon, resembling so-called dominant negativity, awaits further investigation. PMID:20363943

Harada, Eiji; Iida, Ken-Ichiro; Shiota, Susumu; Nakayama, Hiroaki; Yoshida, Shin-Ichi

2010-04-02

85

Versatile selection technology for intracellular protein-protein interactions mediated by a unique bacterial hitchhiker transport mechanism  

PubMed Central

We have developed a reliable genetic selection strategy for isolating interacting proteins based on the “hitchhiker” mechanism of the Escherichia coli twin-arginine translocation (Tat) pathway. This method, designated FLI-TRAP (functional ligand-binding identification by Tat-based recognition of associating proteins), is based on the unique ability of the Tat system to efficiently cotranslocate noncovalent complexes of 2 folded polypeptides. In the FLI-TRAP assay, the protein to be screened for interactions is engineered with an N-terminal Tat signal peptide, whereas the known or putative partner protein is fused to mature TEM-1 ?-lactamase (Bla). Using a series of c-Jun and c-Fos leucine zipper (JunLZ and FosLZ) variants of known affinities, we observed that only those chimeras that expressed well and interacted strongly in the cytoplasm were able to colocalize Bla into the periplasm and confer ?-lactam antibiotic resistance to cells. Likewise, the assay was able to efficiently detect interactions between intracellular single-chain Fv (scFv) antibodies and their cognate antigens. The utility of FLI-TRAP was then demonstrated through random library selections of amino acid substitutions that restored (i) heterodimerization to a noninteracting FosLZ variant, and (ii) antigen binding to a low-affinity scFv antibody. Because Tat substrates must be correctly folded before transport, FLI-TRAP favors the identification of soluble, nonaggregating, protease-resistant protein pairs and, thus, provides a powerful tool for routine selection of interacting partners (e.g., antibody-antigen), without the need for purification or immobilization of the binding target.

Waraho, Dujduan; DeLisa, Matthew P.

2009-01-01

86

Politics and International Legal Obligation  

Microsoft Academic Search

Why do states recognize an obligation to observe the rules of international law? Existing accounts of international legal obligation suffer from the problem of ‘interiority’. They first ground obligation in some internal feature of the international legal system — such as consent, fairness or dialogue — but when these turn out to be insufficient, they fall back on assumptions about

Christian Reus-Smit

2003-01-01

87

The immunosuppressive drug azathioprine inhibits biosynthesis of the bacterial signal molecule cyclic-di-GMP by interfering with intracellular nucleotide pool availability.  

PubMed

In Gram-negative bacteria, production of the signal molecule c-di-GMP by diguanylate cyclases (DGCs) is a key trigger for biofilm formation, which, in turn, is often required for the development of chronic bacterial infections. Thus, DGCs represent interesting targets for new chemotherapeutic drugs with anti-biofilm activity. We searched for inhibitors of the WspR protein, a Pseudomonas aeruginosa DGC involved in biofilm formation and production of virulence factors, using a set of microbiological assays developed in an Escherichia coli strain expressing the wspR gene. We found that azathioprine, an immunosuppressive drug used in the treatment of Crohn's disease, was able to inhibit WspR-dependent c-di-GMP biosynthesis in bacterial cells. However, in vitro enzymatic assays ruled out direct inhibition of WspR DGC activity either by azathioprine or by its metabolic derivative 2-amino-6-mercapto-purine riboside. Azathioprine is an inhibitor of 5-aminoimidazole-4-carboxamide ribotide (AICAR) transformylase, an enzyme involved in purine biosynthesis, which suggests that inhibition of c-di-GMP biosynthesis by azathioprine may be due to perturbation of intracellular nucleotide pools. Consistent with this hypothesis, WspR activity is abolished in an E. coli purH mutant strain, unable to produce AICAR transformylase. Despite its effect on WspR, azathioprine failed to prevent biofilm formation by P. aeruginosa; however, it affected production of extracellular structures in E. coli clinical isolates, suggesting efficient inhibition of c-di-GMP biosynthesis in this bacterium. Our results indicate that azathioprine can prevent biofilm formation in E. coli through inhibition of c-di-GMP biosynthesis and suggest that such inhibition might contribute to its anti-inflammatory activity in Crohn's disease. PMID:23584245

Antoniani, Davide; Rossi, Elio; Rinaldo, Serena; Bocci, Paola; Lolicato, Marco; Paiardini, Alessandro; Raffaelli, Nadia; Cutruzzolà, Francesca; Landini, Paolo

2013-04-14

88

A challenge for 21st century molecular biology and biochemistry: what are the causes of obligate autotrophy and methanotrophy?  

Microsoft Academic Search

We assess the use to which bioinformatics in the form of bacterial genome sequences, functional gene probes and the protein sequence databases can be applied to hypotheses about obligate autotrophy in eubacteria. Obligate methanotrophy and obligate autotrophy among the chemo- and photo-lithotrophic bacteria lack satisfactory explanation a century or more after their discovery. Various causes of these phenomena have been

Ann P. Wood; Jukka P. Aurikko; Donovan P. Kelly

2004-01-01

89

Strategies of genomic integration within insect-bacterial mutualisms  

PubMed Central

Insects, the most diverse group of macroorganisms with 900,000 known species, have been a rich playground for the evolution of symbiotic associations. Symbionts of this enormous animal group include a range of microbial partners. Insects are prone to establishing relationships with intracellular bacteria, which include the most intimate, highly integrated mutualisms known in the biological world. In recent years, an explosion of genomic studies has offered new insights into the molecular, functional, and evolutionary consequences of these insect-bacterial partnerships. In this review, I highlight some insights from genome sequences of bacterial endosymbionts and select insect hosts. Notably, comparisons of facultative versus obligate bacterial mutualists have revealed distinct genome features representing different stages along a shared trajectory of genome reduction. Bacteria associated with the cedar aphid offer a snapshot of a transition from facultative to obligate mutualism, illustrating the genomic basis of this key step along the symbiotic spectrum. In addition, genomes of stable, dual bacterial symbionts reflect independent instances of astonishing metabolic integration. In these systems, synthesis of key nutrients, and perhaps basic cellular processes, require collaboration among co-residing bacteria and their insect host. These findings provide a launching point for a new era of genomic explorations of bacterial-animal symbioses. Future studies promise to reveal symbiotic strategies across a broad ecological and phylogenetic range, to clarify key transitions along a spectrum of interaction types, and to fuel new experimental approaches to dissect the mechanistic basis of intimate host-symbiont associations.

Wernegreen, Jennifer J.

2013-01-01

90

Efficacies of ofloxacin, rifampin, and clindamycin in treatment of Staphylococcus aureus abscesses and correlation with results of an in vitro assay of intracellular bacterial killing.  

PubMed

We studied the efficacies of ofloxacin, rifampin, and clindamycin in a Staphylococcus aureus abscess model and seven antimicrobial regimens in an intracellular killing assay. Ofloxacin plus rifampin was the most effective regimen in the abscess model, and rifampin and ofloxacin were the most active regimens in the intracellular killing assay. PMID:9145896

Bamberger, D M; Herndon, B L; Dew, M; Chern, R P; Mitchell, H; Summers, L E; Marcus, R F; Kim, S C; Suvarna, P R

1997-05-01

91

Utilization of an Intracellular Bacterial Community Pathway in Klebsiella pneumoniae Urinary Tract Infection and the Effects of FimK on Type 1 Pilus Expression?  

PubMed Central

Klebsiella pneumoniae is an important cause of urinary tract infection (UTI), but little is known about its pathogenesis in vivo. The pathogenesis of the K. pneumoniae cystitis isolate TOP52 was compared to that of the uropathogenic Escherichia coli (UPEC) isolate UTI89 in a murine cystitis model. Bladder and kidney titers of TOP52 were lower than those of UTI89 at early time points but similar at later time points. TOP52, like UTI89, formed biofilm-like intracellular bacterial communities (IBCs) within the murine bladder, albeit at significantly lower levels than UTI89. Additionally, filamentation of TOP52 was observed, a process critical for UTI89 evasion of neutrophil phagocytosis and persistence in the bladder. Thus, the IBC pathway is not specific to UPEC alone. We investigated if differences in type 1 pilus expression may explain TOP52's early defect in vivo. The type 1 pilus operon is controlled by recombinase-mediated (fimE, fimB, and fimX) phase variation of an invertible promoter element. We found that K. pneumoniae carries an extra gene of unknown function at the 3? end of its type 1 operon, fimK, and the genome lacks the recombinase fimX. A deletion mutant of fimK was constructed, and TOP52 ?fimK had higher titers and formed more IBCs in the murine cystitis model than wild type. The loss of fimK or expression of E. coli fimX from a plasmid in TOP52 resulted in a larger phase-ON population and higher expression levels of type 1 pili and gave TOP52 the ability to form type 1-dependent biofilms. Complementation with pfimK decreased type 1 pilus expression and biofilm formation of TOP52 ?fimK and decreased UTI89 biofilm formation. Thus, K. pneumoniae appears programmed for minimal expression of type 1 pili, which may explain, in part, why K. pneumoniae is a less prevalent etiologic agent of UTI than UPEC.

Rosen, David A.; Pinkner, Jerome S.; Jones, Jennifer M.; Walker, Jennifer N.; Clegg, Steven; Hultgren, Scott J.

2008-01-01

92

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

93

Classical Labeling of Bacterial Pathogens According to Their Lifestyle in the Host: Inconsistencies and Alternatives  

PubMed Central

An ample understanding of the complex interactions between host and pathogen will improve our ability to develop new prophylactic and therapeutic measures against infection. Precise classification of infectious agents in regards to their infective lifestyles in the host and corresponding pathogenic implications are required because clear concepts are essential to plan fruitful research. Classically, pathogenic bacteria are classified as extracellular, facultative intracellular, and obligate intracellular. In my opinion, this classification is inadequate because, as concluded from data here discussed, it is based on inconsistencies and hyper-valorizes the capacity of the infectious agent replicate in vitro in cell-free media. For a microbial pathogen, what matters is whether intra- or extracellularity is in the context of the in vivo life and in association with pathogenicity. When living as a pathogen in association with its host, what is relevant in microbiological terms is not the ability to grow in artificial cell-free bacteriological media or in environmental niches but whether the intracellular infectious agent, besides the phase of intracellular growth which is behind its label, also is able to live extracellularly in the natural settings of the extracellular territories of their hosts. To eliminate the inconsistencies associated with the classical labeling of bacterial pathogens, I propose that bacterial pathogens be labeled exclusive extracellular, dual intracellular/extracellular and exclusive intracellular based on their infective lifestyle in the host, not in the ability to grow in artificial bacteriological media.

Silva, Manuel T.

2012-01-01

94

The genome of the obligate endobacterium of an AM fungus reveals an interphylum network of nutritional interactions  

PubMed Central

As obligate symbionts of most land plants, arbuscular mycorrhizal fungi (AMF) have a crucial role in ecosystems, but to date, in the absence of genomic data, their adaptive biology remains elusive. In addition, endobacteria are found in their cytoplasm, the role of which is unknown. In order to investigate the function of the Gram-negative Candidatus Glomeribacter gigasporarum, an endobacterium of the AMF Gigaspora margarita, we sequenced its genome, leading to an ?1.72-Mb assembly. Phylogenetic analyses placed Ca. G. gigasporarum in the Burkholderiaceae whereas metabolic network analyses clustered it with insect endobacteria. This positioning of Ca. G. gigasporarum among different bacterial classes reveals that it has undergone convergent evolution to adapt itself to intracellular lifestyle. The genome annotation of this mycorrhizal-fungal endobacterium has revealed an unexpected genetic mosaic where typical determinants of symbiotic, pathogenic and free-living bacteria are integrated in a reduced genome. Ca. G. gigasporarum is an aerobic microbe that depends on its host for carbon, phosphorus and nitrogen supply; it also expresses type II and type III secretion systems and synthesizes vitamin B12, antibiotics- and toxin-resistance molecules, which may contribute to the fungal host's ecological fitness. Ca. G. gigasporarum has an extreme dependence on its host for nutrients and energy, whereas the fungal host is itself an obligate biotroph that relies on a photosynthetic plant. Our work represents the first step towards unraveling a complex network of interphylum interactions, which is expected to have a previously unrecognized ecological impact.

Ghignone, Stefano; Salvioli, Alessandra; Anca, Iulia; Lumini, Erica; Ortu, Giuseppe; Petiti, Luca; Cruveiller, Stephane; Bianciotto, Valeria; Piffanelli, Pietro; Lanfranco, Luisa; Bonfante, Paola

2012-01-01

95

P2X 7 purinergic receptors and extracellular ATP mediate apoptosis of human monocytes\\/macrophages infected with Mycobacterium tuberculosis reducing the intracellular bacterial viability  

Microsoft Academic Search

Mycobacterium tuberculosis (MTB) is a monocyte\\/macrophage (M\\/M) parasite, which has developed several mechanisms to survive and multiply intracellularly. On the other hand, infected cells are engaged in the effort to reduce mycobacterial viability. On this ground, we report that MTB infection predisposes M\\/M to a pro-apoptotic ATP-based signalling, which is aimed at decreasing MTB replication. In fact, we show that

Roberta Placido; Giovanni Auricchio; Simonetta Falzoni; Luca Battistini; Vittorio Colizzi; Ercole Brunetti; Francesco Di Virgilio; Giorgio Mancino

2006-01-01

96

P2X(7) purinergic receptors and extracellular ATP mediate apoptosis of human monocytes/macrophages infected with Mycobacterium tuberculosis reducing the intracellular bacterial viability.  

PubMed

Mycobacterium tuberculosis (MTB) is a monocyte/macrophage (M/M) parasite, which has developed several mechanisms to survive and multiply intracellularly. On the other hand, infected cells are engaged in the effort to reduce mycobacterial viability. On this ground, we report that MTB infection predisposes M/M to a pro-apoptotic ATP-based signalling, which is aimed at decreasing MTB replication. In fact, we show that mycobacterial infection leads to an increased expression of P2X(7) purinergic receptors, which is paralleled by intracellular accumulation and subsequent extracellular release of ATP by infected macrophages. Activation of this signal is conceived to induce apoptosis in MTB-infected cells, since blocking P2X(7) receptor by means of oxidized ATP (oATP) prevents MTB induced cell death. Finally, we show that an ATP stimulation of MTB-infected M/M, besides increasing cellular apoptosis, strongly enhances intracellular MTB killing, as evaluated through Colony Forming Unit assay, and such effect is subverted through oATP pulsing of infected cells. Taken together, our data indicate a role of P2X(7) purinergic receptors in MTB-induced M/M apoptosis, suggesting the existence of an autocrine/paracrine loop leading to apoptosis of infected M/M and the feasible protective role of ATP-triggered cell death in tuberculosis. PMID:17433275

Placido, Roberta; Auricchio, Giovanni; Falzoni, Simonetta; Battistini, Luca; Colizzi, Vittorio; Brunetti, Ercole; Di Virgilio, Francesco; Mancino, Giorgio

2007-04-12

97

ELECTRON MICROSCOPY IN THE STUDY OF INTRACELLULAR PATHOGENS  

Microsoft Academic Search

Chlamydia trachomatis is the causative agent of trachoma, the leading cause of infectious blind- ness worldwide, and is also the most common cause of sexually transmitted disease. Chlamydiae are obligate intracellular bacteria that replicate within a unique intracellular vacuole termed an inclusion. Although chlamydiae are clearly important pathogens, they can be difficult to study due to the lack of genetic

Elizabeth R. FISCHER; Ted HACKSTADT

98

47 CFR 7.5 - General Obligations.  

Code of Federal Regulations, 2012 CFR

...Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL ACCESS TO VOICEMAIL AND INTERACTIVE MENU SERVICES AND EQUIPMENT BY PEOPLE WITH DISABILITIES Obligations-What Must Covered Entities Do? § 7.5 General Obligations. (a)...

2012-10-01

99

45 CFR 83.10 - General obligations.  

Code of Federal Regulations, 2012 CFR

...false General obligations. 83.10 Section 83.10 Public Welfare DEPARTMENT OF...in Admissions Prohibited § 83.10 General obligations. (a) Eligibility...submitting such assurance fails to take whatever remedial action...

2012-10-01

100

45 CFR 83.10 - General obligations.  

Code of Federal Regulations, 2011 CFR

...false General obligations. 83.10 Section 83.10 Public Welfare DEPARTMENT OF...in Admissions Prohibited § 83.10 General obligations. (a) Eligibility...submitting such assurance fails to take whatever remedial action...

2011-10-01

101

Intracellular proteoglycans.  

PubMed Central

Proteoglycans (PGs) are proteins with glycosaminoglycan chains, are ubiquitously expressed and have a wide range of functions. PGs in the extracellular matrix and on the cell surface have been the subject of extensive structural and functional studies. Less attention has so far been given to PGs located in intracellular compartments, although several reports suggest that these have biological functions in storage granules, the nucleus and other intracellular organelles. The purpose of this review is, therefore, to present some of these studies and to discuss possible functions linked to PGs located in different intracellular compartments. Reference will be made to publications relevant for the topics we present. It is beyond the scope of this review to cover all publications on PGs in intracellular locations.

Kolset, Svein Olav; Prydz, Kristian; Pejler, Gunnar

2004-01-01

102

[Family ties and maintenance obligation].  

PubMed

Maintenance obligation is a question frequently addressed in gerontology as an elderly person prepares to enter an institution. Its implementation is a source of conflict within families as well as with professionals involved in these situations. This administrative process, generally long and complex, can shatter family ties and lengthen the time required to obtain support thereby delaying admission to the institution. To tackle these issues, professionals from the Paris Saint-Joseph hospital group have set up meetings bringing together social services, medical services and management representatives. These multi-disciplinary consultations have highlighted the need for management to work with the families of hospitalised patients to remind them of the maintenance obligation in a framework of mediation. PMID:22611896

Manteghetti, Michèle; Reznikoff, Valérie

103

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

104

12 CFR 1270.20 - Consolidated obligations are not obligations of the United States or guaranteed by the United...  

Code of Federal Regulations, 2012 CFR

...Consolidated obligations are not obligations of the United States or guaranteed by the United States. 1270.20 Section 1270.20 Banks and...Consolidated obligations are not obligations of the United States or guaranteed by the United States....

2012-01-01

105

Genetic transformation of an obligate anaerobe, P. gingivalis for FMN-green fluorescent protein expression in studying host-microbe interaction.  

PubMed

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

2011-04-15

106

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.

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

2011-01-01

107

Chemical induced intracellular hyperthermia  

US Patent & Trademark Office Database

An invention relating to therapeutic pharmacological agents and methods to chemically induce intracellular hyperthermia and/or free radicals for the diagnosis and treatment of infections, malignancy and other medical conditions. The invention relates to a process and composition for the diagnosis or killing of cancer cells and inactivation of susceptible bacterial, parasitic, fungal, and viral pathogens by chemically generating heat, and/or free radicals and/or hyperthermia-inducible immunogenic determinants by using mitochondrial uncoupling agents, especially 2,4 dinitrophenol and, their conjugates, either alone or in combination with other drugs, hormones, cytokines and radiation.

2009-12-22

108

Obligate oil-degrading marine bacteria.  

PubMed

Over the past few years, a new and ecophysiologically unusual group of marine hydrocarbon-degrading bacteria - the obligate hydrocarbonoclastic bacteria (OHCB) - has been recognized and shown to play a significant role in the biological removal of petroleum hydrocarbons from polluted marine waters. The introduction of oil or oil constituents into seawater leads to successive blooms of a relatively limited number of indigenous marine bacterial genera--Alcanivorax, Marinobacter, Thallassolituus, Cycloclasticus, Oleispira and a few others (the OHCB)--which are present at low or undetectable levels before the polluting event. The types of OHCB that bloom depend on the latitude/temperature, salinity, redox and other prevailing physical-chemical factors. These blooms result in the rapid degradation of many oil constituents, a process that can be accelerated further by supplementation with limiting nutrients. Genome sequencing and functional genomic analysis of Alcanivorax borkumensis, the paradigm of OHCB, has provided significant insights into the genomic basis of the efficiency and versatility of its hydrocarbon utilization, the metabolic routes underlying its special hydrocarbon diet, and its ecological success. These and other studies have revealed the potential of OHCB for multiple biotechnological applications that include not only oil pollution mitigation, but also biopolymer production and biocatalysis. PMID:17493798

Yakimov, Michail M; Timmis, Kenneth N; Golyshin, Peter N

2007-05-09

109

Thermoleophilum album gen. nov. and sp. nov., a bacterium obligate for thermophily and n -alkane substrates  

Microsoft Academic Search

Several bacterial strains that are obligate for both thermophily and hydrocarbon utilization have been isolated from a number of thermal and non-thermal environments. Mud and water samples obtained from geographic sites across the United States were subjected to enrichment procedures at 60° C with n-heptadecane as sole growth substrate. Organisms forming very small white colonies on agar surfaces were often

K. A. Zarilla; J. J. Perry

1984-01-01

110

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Teaching obligation. 2400.65 ...Conditions § 2400.65 Teaching obligation. Upon receiving...social studies, or political science on a full-time basis...is employed indicating the teaching activities of the Fellow...

2010-10-01

111

45 CFR 2400.65 - Teaching obligation.  

Code of Federal Regulations, 2010 CFR

... 2009-10-01 false Teaching obligation. 2400.65 ...Conditions § 2400.65 Teaching obligation. Upon receiving...social studies, or political science on a full-time basis...is employed indicating the teaching activities of the Fellow...

2009-10-01

112

Coxiella burnetii: host and bacterial responses to infection.  

PubMed

Designation as a Category B biothreat agent has propelled Coxiella burnetii from a relatively obscure, underappreciated, "niche" microorganism on the periphery of bacteriology, to one of possibly great consequence if actually used in acts of bioterrorism. Advances in the study of this microorganism proceeded slowly, primarily because of the difficulty in studying this obligate intracellular pathogen that must be manipulated under biosafety level-3 conditions. The dogged determination of past and current C. burnetii researchers and the application of modern immunological and molecular techniques have more clearly defined the host and bacterial response to infection. This review is intended to provide a basic introduction to C. burnetii and Q fever, while emphasizing immunomodulatory properties, both positive and negative, of Q fever vaccines and C. burnetii infections. PMID:17825460

Waag, David M

2007-08-20

113

45 CFR 63.21 - Obligation and liquidation by grantee.  

Code of Federal Regulations, 2012 CFR

...false Obligation and liquidation by grantee. 63.21 Section 63.21 Public...21 Obligation and liquidation by grantee. Obligations will be considered to have been incurred by a grantee on the basis of documentary evidence...

2012-10-01

114

45 CFR 1226.13 - Obligations of sponsors.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Obligations of sponsors. 1226.13 Section 1226.13 Public...ON ELECTORAL AND LOBBYING ACTIVITIES Sponsor Employee Activities § 1226.13 Obligations of sponsors. (a) It shall be the obligation...

2012-10-01

115

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

116

11 CFR 9034.5 - Net outstanding campaign obligations.  

Code of Federal Regulations, 2013 CFR

...ENTITLEMENTS § 9034.5 Net outstanding campaign obligations...shall submit a statement of net outstanding campaign obligations. The candidate's net outstanding campaign obligations...currency; balances on deposit in banks; savings and loan...

2013-01-01

117

24 CFR 891.755 - Obligations of the family.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Obligations of the family. 891.755 Section 891.755...Projects for the Nonelderly Handicapped Families and Individuals-Section 162 Assistance § 891.755 Obligations of the family. The obligations of the...

2013-04-01

118

Functional genomics of intracellular bacteria.  

PubMed

During the genomic era, a large amount of whole-genome sequences accumulated, which identified many hypothetical proteins of unknown function. Rapidly, functional genomics, which is the research domain that assign a function to a given gene product, has thus been developed. Functional genomics of intracellular pathogenic bacteria exhibit specific peculiarities due to the fastidious growth of most of these intracellular micro-organisms, due to the close interaction with the host cell, due to the risk of contamination of experiments with host cell proteins and, for some strict intracellular bacteria such as Chlamydia, due to the absence of simple genetic system to manipulate the bacterial genome. To identify virulence factors of intracellular pathogenic bacteria, functional genomics often rely on bioinformatic analyses compared with model organisms such as Escherichia coli and Bacillus subtilis. The use of heterologous expression is another common approach. Given the intracellular lifestyle and the many effectors that are used by the intracellular bacteria to corrupt host cell functions, functional genomics is also often targeting the identification of new effectors such as those of the T4SS of Brucella and Legionella. PMID:23564838

de Barsy, Marie; Greub, Gilbert

2013-04-05

119

Genome sequence of Blochmannia pennsylvanicus indicates parallel evolutionary trends among bacterial mutualists of insects.  

PubMed

The distinct lifestyle of obligately intracellular bacteria can alter fundamental forces that drive and constrain genome change. In this study, sequencing the 792-kb genome of Blochmannia pennsylvanicus, an obligate endosymbiont of Camponotus pennsylvanicus, enabled us to trace evolutionary changes that occurred in the context of a bacterial-ant association. Comparison to the genome of Blochmannia floridanus reveals differential loss of genes involved in cofactor biosynthesis, the composition and structure of the cell wall and membrane, gene regulation, and DNA replication. However, the two Blochmannia species show complete conservation in the order and strand orientation of shared genes. This finding of extreme stasis in genome architecture, also reported previously for the aphid endosymbiont Buchnera, suggests that genome stability characterizes long-term bacterial mutualists of insects and constrains their evolutionary potential. Genome-wide analyses of protein divergences reveal 10- to 50-fold faster amino acid substitution rates in Blochmannia compared to related bacteria. Despite these varying features of genome evolution, a striking correlation in the relative divergences of proteins indicates parallel functional constraints on gene functions across ecologically distinct bacterial groups. Furthermore, the increased rates of amino acid substitution and gene loss in Blochmannia have occurred in a lineage-specific fashion, which may reflect life history differences of their ant hosts. PMID:16077009

Degnan, Patrick H; Lazarus, Adam B; Wernegreen, Jennifer J

2005-08-01

120

Genome sequence of Blochmannia pennsylvanicus indicates parallel evolutionary trends among bacterial mutualists of insects  

PubMed Central

The distinct lifestyle of obligately intracellular bacteria can alter fundamental forces that drive and constrain genome change. In this study, sequencing the 792-kb genome of Blochmannia pennsylvanicus, an obligate endosymbiont of Camponotus pennsylvanicus, enabled us to trace evolutionary changes that occurred in the context of a bacterial–ant association. Comparison to the genome of Blochmannia floridanus reveals differential loss of genes involved in cofactor biosynthesis, the composition and structure of the cell wall and membrane, gene regulation, and DNA replication. However, the two Blochmannia species show complete conservation in the order and strand orientation of shared genes. This finding of extreme stasis in genome architecture, also reported previously for the aphid endosymbiont Buchnera, suggests that genome stability characterizes long-term bacterial mutualists of insects and constrains their evolutionary potential. Genome-wide analyses of protein divergences reveal 10- to 50-fold faster amino acid substitution rates in Blochmannia compared to related bacteria. Despite these varying features of genome evolution, a striking correlation in the relative divergences of proteins indicates parallel functional constraints on gene functions across ecologically distinct bacterial groups. Furthermore, the increased rates of amino acid substitution and gene loss in Blochmannia have occurred in a lineage-specific fashion, which may reflect life history differences of their ant hosts.

Degnan, Patrick H.; Lazarus, Adam B.; Wernegreen, Jennifer J.

2005-01-01

121

Caring work, personal obligation and collective responsibility.  

PubMed

Studies of workers in health care and the care of older people disclose tensions that emerge partly from their conflicting obligations. They incur some obligations from the personal relationships they have with clients, but these can be at odds with organizational demands and resource constraints. One implication is the need for policies to recognize the importance of allowing workers some discretion in decison making. Another implication may be that sometimes care workers can meet their obligations to clients only by taking collective action. PMID:14763646

Provis, Chris; Stack, Sue

2004-01-01

122

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

123

7 CFR 982.50 - Restricted obligation.  

Code of Federal Regulations, 2013 CFR

...Order Regulating Handling Control of Distribution § 982.50 Restricted obligation...withheld from handling a quantity, by weight, of certified merchantable hazelnuts...section, the equivalent quantity, by weight as determined under that...

2013-01-01

124

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

125

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

SciTech Connect

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

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

2009-02-25

126

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

Microsoft Academic Search

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

S. Cheng; K. Y. Chen

1987-01-01

127

Autophagy in Immunity Against Intracellular Bacteria  

Microsoft Academic Search

\\u000a Autophagy is an innate immune defense mechanism against various intracellular bacterial pathogens, such as Salmonella enterica serovar Typhimurium (S. typhimurium), Listeria monocytogenes and Shigella flexneri. S. typhimurium uses type three secretion systems (T3SSs) to invade mammalian cells and replicate in Salmonella-containing vacuoles (SCVs). A small population of intracellular S. typhimurium is targeted by autophagy shortly after infection. Evidence suggests that

Ju Huang; John H. Brumell

128

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

PubMed Central

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

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

2009-01-01

129

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.

Sider, R C; Clements, C D

1984-01-01

130

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.

Chong, Audrey; Celli, Jean

2010-01-01

131

Can't take the heat: high temperature depletes bacterial endosymbionts of ants.  

PubMed

Members of the ant tribe Camponotini have coevolved with Blochmannia, an obligate intracellular bacterial mutualist. This endosymbiont lives within host bacteriocyte cells that line the ant midgut, undergoes maternal transmission from host queens to offspring, and contributes to host nutrition via nitrogen recycling and nutrient biosynthesis. While elevated temperature has been shown to disrupt obligate bacterial mutualists of some insects, its impact on the ant-Blochmannia partnership is less clear. Here, we test the effect of heat on the density of Blochmannia in two related Camponotus species in the lab. Transcriptionally active Blochmannia were quantified using RT-qPCR as the ratio of Blochmannia 16S rRNA to ant host elongation factor 1-? transcripts. Our results showed that 4 weeks of heat treatment depleted active Blochmannia by >99 % in minor workers and unmated queens. However, complete elimination of Blochmannia transcripts rarely occurred, even after 16 weeks of heat treatment. Possible mechanisms of observed thermal sensitivity may include extreme AT-richness and related features of Blochmannia genomes, as well as host stress responses. Broadly, the observed depletion of an essential microbial mutualist in heat-treated ants is analogous to the loss of zooanthellae during coral bleaching. While the ecological relevance of Blochmannia's thermal sensitivity is uncertain, our results argue that symbiont dynamics should be part of models predicting how ants and other animals will respond and adapt to a warming climate. PMID:23872930

Fan, Yongliang; Wernegreen, Jennifer J

2013-07-20

132

Inhibition of intracellular replication by pyridinylimidazoles  

US Patent & Trademark Office Database

Substituted pyridinylimidazoles SB203580 and SB202190 strongly inhibit replication and cause stage conversion from active tachyzoites to relatively dormant bradyzoites of the medically important, obligate intracellular parasite Toxoplasma gondii. The pyridinylimidazoles probably mediate these effects by acting on a presently unidentified homologue(s) of human p38-mitogen activated protein kinase present in the tachyzoites. SB203580 also significantly enhanced in vitro inhibition of T. gondii replication by the approved anti-Toxoplasma drug pyrimethamine. The pyridinylimidazoles and related compounds disclosed herein could thus be significant adjuncts to currently available therapies.

2003-11-18

133

Image analyzing method to evaluate in situ bioluminescence from an obligate anaerobe cultivated under various dissolved oxygen concentrations.  

PubMed

An image analyzing method was developed to evaluate in situ bioluminescence expression, without exposing the culture sample to the ambient oxygen atmosphere. Using this method, we investigated the effect of dissolved oxygen concentration on bioluminescence from an obligate anaerobe Bifidobacterium longum expressing bacterial luciferase which catalyzes an oxygen-requiring bioluminescent reaction. PMID:23040354

Ninomiya, Kazuaki; Yamada, Ryuji; Matsumoto, Masami; Fukiya, Satoru; Katayama, Takane; Ogino, Chiaki; Shimizu, Nobuaki

2012-10-04

134

48 CFR 519.7013 - Obligation.  

Code of Federal Regulations, 2011 CFR

...gé Program 519.7013 Obligation. (a) The mentor or protégé may terminate the Agreement in accordance with 519.7010. The mentor will notify the Mentor-Protégé Program Manager and the contracting officer, in writing, at least 30...

2011-10-01

135

48 CFR 519.7013 - Obligation.  

Code of Federal Regulations, 2012 CFR

...gé Program 519.7013 Obligation. (a) The mentor or protégé may terminate the Agreement in accordance with 519.7010. The mentor will notify the Mentor-Protégé Program Manager and the contracting officer, in writing, at least 30...

2012-10-01

136

Ethical obligations of computing center personnel  

Microsoft Academic Search

Ethical issues often arise between computing center personnel and other university members concerning the appropriate use of computer resources, the safeguarding of information, the ownership of software, the giving of credit for computer-related work, and many other areas. These issues take the form of ethical obligations, which are the just and fair dealings that people have with other people, dealings

Gary Abshire

1981-01-01

137

40 CFR 1043.30 - General obligations.  

Code of Federal Regulations, 2013 CFR

...EMISSIONS FROM MARINE ENGINES AND VESSELS SUBJECT TO THE MARPOL PROTOCOL § 1043.30 General obligations. (a) 33 U.S.C. 1907 prohibits any person from violating any provisions of the MARPOL Protocol, whether or not they are a manufacturer,...

2013-07-01

138

Communities, obligations and health-care  

Microsoft Academic Search

This paper examines the notion that, in the modern world, a just community will find it necessary to supply a decent minimum of health-care as well as a decent minimum of other basic needs to its members. The argument that health-care is an obligation of the just community is made by examining concepts of health, and the natural lottery as

Erich H. Loewy

1987-01-01

139

Evolution of signal transduction in intracellular symbiosis  

Microsoft Academic Search

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

Catherine Kistner; Martin Parniske

2002-01-01

140

Azithromycin effectiveness against intracellular infections of Francisella  

Microsoft Academic Search

BACKGROUND: Macrolide antibiotics are commonly administered for bacterial respiratory illnesses. Azithromycin (Az) is especially noted for extremely high intracellular concentrations achieved within macrophages which is far greater than the serum concentration. Clinical strains of Type B Francisella (F.) tularensis have been reported to be resistant to Az, however our laboratory Francisella strains were found to be sensitive. We hypothesized that

Saira Ahmad; Lyman Hunter; Aiping Qin; Barbara J Mann; Monique L van Hoek

2010-01-01

141

Fluorescence labeling of bacteria for studies of intracellular pathogenesis  

Microsoft Academic Search

Interactions between intracellular bacterial pathogens and their eukaryotic cellular hosts or targets are often studied with fluorescence-based techniques such as fluorescence microscopy and flow cytometry. We tested whether the intracellular bacterial pathogens L. monocytogenes, M. avium, M. tuberculosis, and S. typhimurium could be labeled by growth in broth containing the fluorochromes carboxy-X-rhodamine (CR), a hydrazine derivative of fluorescein (FH), and

Douglas A Drevets; Alison M Elliott

1995-01-01

142

18 CFR 367.22 - Accounting for asset retirement obligations.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

143

38 CFR 17.608 - Deferment of obligated service.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

144

13 CFR 400.213 - Termination of obligations.  

Code of Federal Regulations, 2013 CFR

...obligations. 400.213 Section 400.213 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.213 Termination of obligations. The Board shall...

2013-01-01

145

13 CFR 400.213 - Termination of obligations.  

Code of Federal Regulations, 2012 CFR

...obligations. 400.213 Section 400.213 Business Credit and Assistance EMERGENCY STEEL GUARANTEE LOAN BOARD EMERGENCY STEEL GUARANTEE LOAN PROGRAM Steel Guarantee Loans § 400.213 Termination of obligations. The Board shall...

2012-01-01

146

22 CFR 62.9 - General obligations of sponsors.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false General obligations of sponsors. 62.9 Section 62.9 Foreign... § 62.9 General obligations of sponsors. (a) Adherence to Department of State regulations. Sponsors are required to adhere to all...

2013-04-01

147

29 CFR 102.164 - Review of the obligation.  

Code of Federal Regulations, 2013 CFR

... false Review of the obligation. 102...Relating to Labor NATIONAL LABOR RELATIONS BOARD...REGULATIONS, SERIES 8 Debt-Collection Procedures...164 Review of the obligation. (a...existence or amount of the debt as set forth in...

2013-07-01

148

29 CFR 102.175 - Agency review of the obligation.  

Code of Federal Regulations, 2013 CFR

... Agency review of the obligation. 102...Relating to Labor NATIONAL LABOR RELATIONS BOARD...REGULATIONS, SERIES 8 Debt Collection Procedures... Agency review of the obligation. (a...for collection of the debt will consider...

2013-07-01

149

47 CFR 76.56 - Signal carriage obligations.  

Code of Federal Regulations, 2010 CFR

...Telecommunication 4 2009-10-01 2009-10-01 false Signal carriage obligations. 76.56 Section 76.56...TELEVISION SERVICE Carriage of Television Broadcast Signals § 76.56 Signal carriage obligations. (a) Carriage of...

2009-10-01

150

47 CFR 76.56 - Signal carriage obligations.  

Code of Federal Regulations, 2010 CFR

...Telecommunication 4 2010-10-01 2010-10-01 false Signal carriage obligations. 76.56 Section 76.56...TELEVISION SERVICE Carriage of Television Broadcast Signals § 76.56 Signal carriage obligations. (a) Carriage of...

2010-10-01

151

Obligate vertebrate scavengers must be large soaring fliers  

Microsoft Academic Search

Among extant vertebrates, only the 23 species of vulture are obligate scavengers. We use an energetic modelling approach to explore the constraints imposed by an obligate scavenging lifestyle, and to ask whether obligate scavengers must always be avian and generally large-bodied users of soaring flight. Our model found that aerial scavengers always out-competed postulated terrestrial ones, mainly because flight allows

Graeme D. Ruxton; David C. Houston

2004-01-01

152

Bacterial DNA Sifted from the Trichoplax adhaerens (Animalia: Placozoa) Genome Project Reveals a Putative Rickettsial Endosymbiont  

PubMed Central

Eukaryotic genome sequencing projects often yield bacterial DNA sequences, data typically considered as microbial contamination. However, these sequences may also indicate either symbiont genes or lateral gene transfer (LGT) to host genomes. These bacterial sequences can provide clues about eukaryote–microbe interactions. Here, we used the genome of the primitive animal Trichoplax adhaerens (Metazoa: Placozoa), which is known to harbor an uncharacterized Gram-negative endosymbiont, to search for the presence of bacterial DNA sequences. Bioinformatic and phylogenomic analyses of extracted data from the genome assembly (181 bacterial coding sequences [CDS]) and trace read archive (16S rDNA) revealed a dominant proteobacterial profile strongly skewed to Rickettsiales (Alphaproteobacteria) genomes. By way of phylogenetic analysis of 16S rDNA and 113 proteins conserved across proteobacterial genomes, as well as identification of 27 rickettsial signature genes, we propose a Rickettsiales endosymbiont of T. adhaerens (RETA). The majority (93%) of the identified bacterial CDS belongs to small scaffolds containing prokaryotic-like genes; however, 12 CDS were identified on large scaffolds comprised of eukaryotic-like genes, suggesting that T. adhaerens might have recently acquired bacterial genes. These putative LGTs may coincide with the placozoan’s aquatic niche and symbiosis with RETA. This work underscores the rich, and relatively untapped, resource of eukaryotic genome projects for harboring data pertinent to host–microbial interactions. The nature of unknown (or poorly characterized) bacterial species may only emerge via analysis of host genome sequencing projects, particularly if these species are resistant to cell culturing, as are many obligate intracellular microbes. Our work provides methodological insight for such an approach.

Driscoll, Timothy; Gillespie, Joseph J.; Nordberg, Eric K.; Azad, Abdu F.; Sobral, Bruno W.

2013-01-01

153

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

2010-06-15

154

Caveolin-2 associates with intracellular chlamydial inclusions independently of caveolin-1  

PubMed Central

Background Lipid raft domains form in plasma membranes of eukaryotic cells by the tight packing of glycosphingolipids and cholesterol. Caveolae are invaginated structures that form in lipid raft domains when the protein caveolin-1 is expressed. The Chlamydiaceae are obligate intracellular bacterial pathogens that replicate entirely within inclusions that develop from the phagocytic vacuoles in which they enter. We recently found that host cell caveolin-1 is associated with the intracellular vacuoles and inclusions of some chlamydial strains and species, and that entry of those strains depends on intact lipid raft domains. Caveolin-2 is another member of the caveolin family of proteins that is present in caveolae, but of unknown function. Methods We utilized a caveolin-1 negative/caveolin-2 positive FRT cell line and laser confocal immunofluorescence techniques to visualize the colocalization of caveolin-2 with the chlamydial inclusions. Results We show here that in infected HeLa cells, caveolin-2, as well as caveolin-1, colocalizes with inclusions of C. pneumoniae (Cp), C. caviae (GPIC), and C. trachomatis serovars E, F and K. In addition, caveolin-2 also associates with C. trachomatis serovars A, B and C, although caveolin-1 did not colocalize with these organisms. Moreover, caveolin-2 appears to be specifically, or indirectly, associated with the pathogens at the inclusion membranes. Using caveolin-1 deficient FRT cells, we show that although caveolin-2 normally is not transported out of the Golgi in the absence of caveolin-1, it nevertheless colocalizes with chlamydial inclusions in these cells. However, our results also show that caveolin-2 did not colocalize with UV-irradiated Chlamydia in FRT cells, suggesting that in these caveolin-1 negative cells, pathogen viability and very likely pathogen gene expression are necessary for the acquisition of caveolin-2 from the Golgi. Conclusion Caveolin-2 associates with the chlamydial inclusion independently of caveolin-1. The function of caveolin-2, either in the uninfected cell or in the chlamydial developmental cycle, remains to be elucidated. Nevertheless, this second caveolin protein can now be added to the small number of host proteins that are associated with the inclusions of this obligate intracellular pathogen.

Webley, Wilmore C; Norkin, Leonard C; Stuart, Elizabeth S

2004-01-01

155

MICROSPORIDIA: Biology and Evolution of Highly Reduced Intracellular Parasites  

Microsoft Academic Search

? Abstract Microsporidia are a large group,of microbial,eukaryotes,composed exclusively of obligate intracellular parasites of other eukaryotes. Almost 150 years of microsporidian,research has led to a basic understanding,of many,aspects of mi- crosporidian biology, especially their unique and highly specialized mode of infection, where,the parasite enters its host through,a projectile tube that is expelled,at high velocity. Molecular biology and genomic,studies on microsporidia,have

Patrick J. Keeling; Naomi M. Fast

2002-01-01

156

Acquisition of polyamines by the obligate intracytoplasmic bacterium Rickettsia prowazekii.  

PubMed Central

Both the polyamine content and the route of acquisition of polyamines by Rickettsia prowazekii, an obligate intracellular parasitic bacterium, were determined. The rickettsiae grew normally in an ornithine decarboxylase mutant of the Chinese hamster ovary (C55.7) cell line whether or not putrescine, which this host cell required in order to grow, was present. The rickettsiae contained approximately 6 mM putrescine, 5 mM spermidine, and 3 mM spermine when cultured in the presence or absence of putrescine. Neither the transport of putrescine and spermidine by the rickettsiae nor a measurable rickettsial ornithine decarboxylase activity could be demonstrated. However, we demonstrated the de novo synthesis of polyamines from arginine by the rickettsiae. Arginine decarboxylase activity (29 pmol of 14CO2 released per h per 10(8) rickettsiae) was measured in the rickettsiae growing within their host cell. A markedly lower level of this enzymatic activity was observed in cell extracts of R. prowazekii and could be completely inhibited with 1 mM difluoromethylarginine, an irreversible inhibitor of the enzyme. R. prowazekii failed to grow in C55.7 cells that had been cultured in the presence of 1 mM difluoromethylarginine. After rickettsiae were grown in C55.7 in the presence of labeled arginine, the specific activities of arginine in the host cell cytoplasm and polyamines in the rickettsiae were measured; these measurements indicated that 100% of the total polyamine content of R. prowazekii was derived from arginine.

Speed, R R; Winkler, H H

1990-01-01

157

Reduction of ribonucleotides by the obligate intracytoplasmic bacterium Rickettsia prowazekii.  

PubMed Central

Rickettsia prowazekii, an obligate intracellular parasitic bacterium, was shown to have a ribonucleotide reductase that would allow the rickettsiae to obtain the deoxyribonucleotides needed for DNA synthesis from rickettsial ribonucleotides rather than from transport. In the presence of hydroxyurea, R. prowazekii failed to grow in mouse L929 cells or SC2 cells (a hydroxyurea-resistant cell line), which suggested that R. prowazekii contains a functional ribonucleotide reductase. This enzymatic activity was demonstrated by the conversion of ADP to dADP and CDP to dCDP, using (i) a crude extract of Renografin-purified R. prowazekii that had been harvested from infected yolk sacs and (ii) high-performance liquid chromatographic analysis. The rickettsial ribonucleotide reductase utilized ribonucleoside diphosphates as substrates, required magnesium and a reducing agent, and was inhibited by hydroxyurea. ADP reduction was stimulated by dGTP and inhibited by dATP. CDP reduction was stimulated by ATP and adenylylimido-diphosphate and inhibited by dATP and dGTP. These characteristics provided strong evidence that the rickettsial enzyme is a nonheme iron-containing enzyme similar to those found in mammalian cells and aerobic Escherichia coli.

Cai, J; Speed, R R; Winkler, H H

1991-01-01

158

Biochemical Stratagem for Obligate Parasitism of Eukaryotic Cells by Coxiella burnetii  

Microsoft Academic Search

Coxiella burnetti, the etiologic agent of Q fever, is an oligate intracellular parasite of eukaryotes. Unlike the majority of successful bacterial parasites, which escape the bactericidal environment of the phagolysosome by various means, C. burnetii multiplies only in the phagolysosome. In view of the relatively harsh environment inhabited by C. burnetii, we have examined (i) the in vitro metabolism of

Ted Hackstadt; Jim C. Williams

1981-01-01

159

Strategies for Intracellular Survival of Burkholderia pseudomallei  

PubMed Central

Burkholderia pseudomallei is the causative agent of melioidosis, a disease with high mortality that is prevalent in tropical regions of the world. A key component of the pathogenesis of melioidosis is the ability of B. pseudomallei to enter, survive, and replicate within mammalian host cells. For non-phagocytic cells, bacterial adhesins have been identified both on the bacterial surface and associated with Type 4 pili. Cell invasion involves components of one or more of the three Type 3 Secretion System clusters, which also mediate, at least in part, the escape of bacteria from the endosome into the cytoplasm, where bacteria move by actin-based motility. The mechanism of actin-based motility is not clearly understood, but appears to differ from characterized mechanisms in other bacterial species. A small proportion of intracellular bacteria is targeted by host cell autophagy, involving direct recruitment of LC3 to endosomes rather than through uptake by canonical autophagosomes. However, the majority of bacterial cells are able to circumvent autophagy and other intracellular defense mechanisms such as the induction of inducible nitric oxide synthase, and then replicate in the cytoplasm and spread to adjacent cells via membrane fusion, resulting in the formation of multi-nucleated giant cells. A potential role for host cell ubiquitin in the autophagic response to bacterial infection has recently been proposed.

Allwood, Elizabeth M.; Devenish, Rodney J.; Prescott, Mark; Adler, Ben; Boyce, John D.

2011-01-01

160

Apoptotic mimicry by an obligate intracellular parasite downregulates macrophage microbicidal activity  

Microsoft Academic Search

Programmed cell death by apoptosis of unnecessary or potentially harmful cells is clearly beneficial to multicellular organisms [1]. Proper functioning of such a program demands that the removal of dying cells proceed without an inflammatory reaction [2]. Phosphatidylserine (PS) is one of the ligands displayed by apoptotic cells that participates in their noninflammatory removal when recognized by neighboring phagocytes [3].

José Mario de Freitas Balanco; Maria Elisabete Costa Moreira; Adriana Bonomo; Patricia Torres Bozza; Gustavo Amarante-Mendes; Claude Pirmez; Marcello André Barcinski

2001-01-01

161

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

PubMed

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

Tamir, Sivan

2013-03-01

162

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

163

Rab11-family of interacting protein 2 associates with chlamydial inclusions through its Rab-binding domain and promotes bacterial multiplication.  

PubMed

Chlamydia trachomatis, an obligate intracellular pathogen, survives within host cells in a special compartment named 'inclusion' and takes advantage of host vesicular transport pathways for its growth and replication. Rab GTPases are key regulatory proteins of intracellular trafficking. Several Rabs, among them Rab11 and Rab14, are implicated in chlamydial development. FIP2, a member of the Rab11-Family of Interacting Proteins, presents at the C-terminus a Rab-binding domain that interacts with both Rab11 and Rab14. In this study, we determined and characterized the recruitment of endogenous and GFP-tagged FIP2 to the chlamydial inclusions. The recruitment of FIP2 is specific since other members of the Rab11-Family of Interacting Proteins do not associate with the chlamydial inclusions. The Rab-binding domain of FIP2 is essential for its association. Our results indicate that FIP2 binds to Rab11 at the chlamydial inclusion membrane through its Rab-binding domain. The presence of FIP2 at the chlamydial inclusion favours the recruitment of Rab14. Furthermore, our results show that FIP2 promotes inclusion development and bacterial replication. In agreement, the silencing of FIP2 decreases the bacterial progeny. C.?trachomatis likely recruits FIP2 to hijack host intracellular trafficking to redirect vesicles full of nutrients towards the inclusion. PMID:23006599

Leiva, Natalia; Capmany, Anahí; Damiani, María Teresa

2012-11-01

164

A challenge for 21st century molecular biology and biochemistry: what are the causes of obligate autotrophy and methanotrophy?  

PubMed

We assess the use to which bioinformatics in the form of bacterial genome sequences, functional gene probes and the protein sequence databases can be applied to hypotheses about obligate autotrophy in eubacteria. Obligate methanotrophy and obligate autotrophy among the chemo- and photo-lithotrophic bacteria lack satisfactory explanation a century or more after their discovery. Various causes of these phenomena have been suggested, which we review in the light of the information currently available. Among these suggestions is the absence in vivo of a functional alpha-ketoglutarate dehydrogenase. The advent of complete and partial genome sequences of diverse autotrophs, methylotrophs and methanotrophs makes it possible to probe the reasons for the absence of activity of this enzyme. We review the role and evolutionary origins of the Krebs cycle in relation to autotrophic metabolism and describe the use of in silico methods to probe the partial and complete genome sequences of a variety of obligate genera for genes encoding the subunits of the alpha-ketoglutarate dehydrogenase complex. Nitrosomonas europaea and Methylococcus capsulatus, which lack the functional enzyme, were found to contain the coding sequences for the E1 and E2 subunits of alpha-ketoglutarate dehydrogenase. Comparing the predicted physicochemical properties of the polypeptides coded by the genes confirmed the putative gene products were similar to the active alpha-ketoglutarate dehydrogenase subunits of heterotrophs. These obligate species are thus genomically competent with respect to this enzyme but are apparently incapable of producing a functional enzyme. Probing of the full and incomplete genomes of some cyanobacterial and methanogenic genera and Aquifex confirms or suggests the absence of the genes for at least one of the three components of the alpha-ketoglutarate dehydrogenase complex in these obligate organisms. It is recognized that absence of a single functional enzyme may not explain obligate autotrophy in all cases and may indeed be only be one of a number of controls that impose obligate metabolism. Availability of more genome sequences from obligate genera will enable assessment of whether obligate autotrophy is due to the absence of genes for a few or many steps in organic compound metabolism. This problem needs the technologies and mindsets of the present generation of molecular microbiologists to resolve it. PMID:15449607

Wood, Ann P; Aurikko, Jukka P; Kelly, Donovan P

2004-06-01

165

Tails of Bacterial Motility  

NASA Astrophysics Data System (ADS)

The cytoplasm of living cells provides a complex fluid environment in which intracellular bacteria live and move. By analyzing the easily visible curved actin ``comet-tail'' of polymerization-based-motility bacteria such as Listeria monocytogenes, we can learn about sub-micron structure and dynamics of the tail and of the bacterial surface enzyme that catalyzes tail formation. By characterizing the motility, we can transform such motile systems into probes of the cytoplasmic environment.

Rutenberg, Andrew; Grant, Martin

2001-03-01

166

Intracellular invasion of Orientia tsutsugamushi activates inflammasome in asc-dependent manner.  

PubMed

Orientia tsutsugamushi, a causative agent of scrub typhus, is an obligate intracellular bacterium, which escapes from the endo/phagosome and replicates in the host cytoplasm. O. tsutsugamushi infection induces production of pro-inflammatory mediators including interleukin-1? (IL-1?), which is secreted mainly from macrophages upon cytosolic stimuli by activating cysteine protease caspase-1 within a complex called the inflammasome, and is a key player in initiating and maintaining the inflammatory response. However, the mechanism for IL-1? maturation upon O. tsutsugamushi infection has not been identified. In this study, we show that IL-1 receptor signaling is required for efficient host protection from O. tsutsugamushi infection. Live Orientia, but not heat- or UV-inactivated Orientia, activates the inflammasome through active bacterial uptake and endo/phagosomal maturation. Furthermore, Orientia-stimulated secretion of IL-1? and activation of caspase-1 are ASC- and caspase-1- dependent since IL-1? production was impaired in Asc- and caspase-1-deficient macrophages but not in Nlrp3-, Nlrc4- and Aim2-deficient macrophages. Therefore, live O. tsutsugamushi triggers ASC inflammasome activation leading to IL-1? production, which is a critical innate immune response for effective host defense. PMID:22723924

Koo, Jung-Eun; Hong, Hye-Jin; Dearth, Andrea; Kobayashi, Koichi S; Koh, Young-Sang

2012-06-18

167

The Obligation to Participate in Biomedical Research  

PubMed Central

The prevailing view is that participation in biomedical research is above and beyond the call of duty. While some commentators have offered reasons against this, we propose a novel public goods argument for an obligation to participate in biomedical research. Biomedical knowledge is a public good, available to any individual even if that individual does not contribute to it. Participation in research is a critical way to support that important public good. Consequently, we all have a duty to participate. The current social norm is that people participate only if they have a good reason to do so. The public goods argument implies that people should participate unless they have a good reason not to. Such a shift would be of great aid to the progress of biomedical research, eventually making our society significantly healthier and longer-lived.

Schaefer, G. Owen; Emanuel, Ezekiel J.; Wertheimer, Alan

2009-01-01

168

Intracellular aquaporins: clues for intracellular water transport?  

Microsoft Academic Search

Aquaporins (AQPs) are usually present at the plasma membrane to regulate influx and outflow of water and small molecules.\\u000a They are important for the regulation of water homeostasis for the cells and organisms. AQPs are also present inside the cell,\\u000a at the membranes of intracellular organelles. The roles of such AQPs have not yet been established. They will be clues

Kenma Nozaki; Daishi Ishii; Kenichi Ishibashi

2008-01-01

169

Intracellular Parasite Invasion Strategies  

NASA Astrophysics Data System (ADS)

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

Sibley, L. D.

2004-04-01

170

Deconfounding Distance Effects in Judgments of Moral Obligation  

ERIC Educational Resources Information Center

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

Nagel, Jonas; Waldmann, Michael R.

2013-01-01

171

18 CFR 37.8 - Obligations of OASIS users.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Obligations of OASIS users. 37.8 Section 37.8 Conservation...SAME-TIME INFORMATION SYSTEMS § 37.8 Obligations of OASIS users. Each OASIS user must notify the Responsible Party one...

2009-04-01

172

18 CFR 37.8 - Obligations of OASIS users.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Obligations of OASIS users. 37.8 Section 37.8 Conservation...SAME-TIME INFORMATION SYSTEMS § 37.8 Obligations of OASIS users. Each OASIS user must notify the Responsible Party one...

2010-04-01

173

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

174

High Noon and the Problems of American Political Obligation  

Microsoft Academic Search

The Western drama High Noon introduces political considerations deeper than the maelstrom of American anticommunism of the 1950s against which it is most often viewed. It presents the central problems of modern political obligation as arising out of an encounter between Aristotelian and Lockean ideas about marriage, friendship, consent and coercion, and religious obligation. The marshal Kane, representing the altered

J. Jeffrey Tillman

2007-01-01

175

Intracellular functions of galectins  

Microsoft Academic Search

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

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

2002-01-01

176

Toward Intracellular Targeted Delivery of Cancer Therapeutics  

PubMed Central

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

Pandya, Hetal; Debinski, Waldemar

2013-01-01

177

Neutrophils Mediate Immunopathology and Negatively Regulate Protective Immune Responses during Fatal Bacterial Infection-Induced Toxic Shock  

PubMed Central

Ehrlichia chaffeensis is an obligate intracellular bacterium that infects primarily monocytes and macrophages and causes potentially fatal human monocytic ehrlichiosis (HME) that mimics toxic-shock-like syndrome in immunocompetent hosts. Early recruitment of neutrophils to the sites of infection is critical for the control of bacterial infection and inflammatory responses. We recently observed rapid and sustained neutrophil recruitment at a primary site of infection (peritoneum) following lethal murine ehrlichial infection compared to innocuous ehrlichial infection. We examined here the contribution of neutrophils to protective immunity or immunopathology during infection with monocytic Ehrlichia. Unexpectedly, depletion of neutrophils from lethally infected mice enhanced bacterial elimination, decreased immune-mediated pathology, and prolonged survival. Furthermore, compared to lethally infected sham controls, neutrophil depletion in infected mice resulted in amelioration of pathogenic responses, as evidenced by a decreased number of tumor necrosis factor alpha (TNF-?)-producing CD8+ T cells, which is known to mediate immunopathology and toxic shock in a murine model of fatal ehrlichiosis. Although neutrophil depletion did not influence the number of CD4+ Th1 cells and NKT cells producing gamma interferon (IFN-?), it increased the ratio of IFN-?- to IL-10-producing NKT cells as well as the ratio of IFN-? to interleukin 10 (IL-10) transcripts in the liver. This may ameliorate the net suppressive effect of IL-10 on IFN-?-mediated activation of infected macrophages and thus may account for the enhanced bacterial elimination. Finally, transcriptional analysis of gene expression in the liver indicated that neutrophils contribute to overproduction of cytokines and chemokines during fatal ehrlichiosis. In conclusion, these results revealed an unexpected role of neutrophils in supporting bacterial replication indirectly and promoting immunopathology during severe infection with an intracellular bacterium.

Yang, Qin; Ghose, Purnima

2013-01-01

178

Review of International Experience with Renewable Energy Obligation Support Mechanisms  

SciTech Connect

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

Wiser, R.

2005-06-01

179

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.

1993-01-01

180

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. 96.14 Section 96.14 Public...SERVICES GENERAL ADMINISTRATION BLOCK GRANTS General Procedures § 96.14 Time period for obligation and expenditure of grant funds. (a) Obligations....

2011-10-01

181

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

182

69 FR 20845 - Rules and Regulations Implementing Minimum Customer Account Record Exchange Obligations on All...  

Federal Register 2010, 2011, 2012, 2013

...Customer Account Record Exchange Obligations on All Local and Interexchange Carriers AGENCY...Record Exchange (CARE) obligations on all local and interexchange carriers and, in...Customer Account Record Exchange Obligations on All Local and Interexchange Carriers, CG...

2004-04-19

183

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

Code of Federal Regulations, 2013 CFR

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

2013-01-01

184

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

2006-09-28

185

Bacterial Fertilizers.  

National Technical Information Service (NTIS)

The term bacterial (microbial) fertilizers refers to preparations containing primarily active strains of the microorganisms mainly bacteria in sufficient numbers. This report covers various aspects of bacterial fertilizers: Nitrogen Preparation and Usage;...

W. V. B. Sundra Rao

1981-01-01

186

Sterile-?- and armadillo motif-containing protein inhibits the TRIF-dependent downregulation of signal regulatory protein ? to interfere with intracellular bacterial elimination in Burkholderia pseudomallei-infected mouse macrophages.  

PubMed

Burkholderia pseudomallei, the causative agent of melioidosis, evades macrophage killing by suppressing the TRIF-dependent pathway, leading to inhibition of inducible nitric oxide synthase (iNOS) expression. We previously demonstrated that virulent wild-type B. pseudomallei inhibits the TRIF-dependent pathway by upregulating sterile-?- and armadillo motif-containing protein (SARM) and by inhibiting downregulation of signal regulatory protein ? (SIRP?); both molecules are negative regulators of Toll-like receptor signaling. In contrast, the less virulent lipopolysaccharide (LPS) mutant of B. pseudomallei is unable to exhibit these features and is susceptible to macrophage killing. However, the functional relationship of these two negative regulators in the evasion of macrophage defense has not been elucidated. We demonstrated here that SIRP? downregulation was observed after inhibition of SARM expression by small interfering RNA in wild-type-infected macrophages, indicating that SIRP? downregulation is regulated by SARM. Furthermore, this downregulation requires activation of the TRIF signaling pathway, as we observed abrogation of SIRP? downregulation as well as restricted bacterial growth in LPS mutant-infected TRIF-depleted macrophages. Although inhibition of SARM expression is correlated to SIRP? downregulation and iNOS upregulation in gamma interferon-activated wild-type-infected macrophages, these phenomena appear to bypass the TRIF-dependent pathway. Similar to live bacteria, the wild-type LPS is able to upregulate SARM and to prevent SIRP? downregulation, implying that the LPS of B. pseudomallei may play a crucial role in regulating the expression of these two negative regulators. Altogether, our findings show a previously unrecognized role of B. pseudomallei-induced SARM in inhibiting SIRP? downregulation-mediated iNOS upregulation, facilitating the ability of the bacterium to multiply in macrophages. PMID:23836818

Baral, Pankaj; Utaisincharoen, Pongsak

2013-07-08

187

29 CFR 500.60 - Farm labor contractors' recruitment, contractual and general obligations.  

Code of Federal Regulations, 2013 CFR

...false Farm labor contractors' recruitment, contractual and general obligations...60 Farm labor contractors' recruitment, contractual and general obligations...Act imposes certain specific recruitment, contractual and...

2013-07-01

188

7 CFR 1942.316 - Grant approval, fund obligation and third party financial assistance.  

Code of Federal Regulations, 2013 CFR

...Grant approval, fund obligation and third party financial assistance. 1942...approval, fund obligation and third party financial assistance. (a...1942 of this chapter. (c) Third party financial assistance....

2013-01-01

189

7 CFR 1942.316 - Grant approval, fund obligation and third party financial assistance.  

Code of Federal Regulations, 2012 CFR

...Grant approval, fund obligation and third party financial assistance. 1942...approval, fund obligation and third party financial assistance. (a...1942 of this chapter. (c) Third party financial assistance....

2012-01-01

190

Intracellular mechanisms of aminoglycoside-induced cytotoxicity  

PubMed Central

Since introduction into clinical practice over 60 years ago, aminoglycoside antibiotics remain important drugs in the treatment of bacterial infections, cystic fibrosis and tuberculosis. However, the ototoxic and nephrotoxic properties of these drugs are still a major clinical problem. Recent advances in molecular biology and biochemistry have begun to uncover the intracellular actions of aminoglycosides that lead to cytotoxicity. In this review, we discuss intracellular binding targets of aminoglycosides, highlighting specific aminoglycoside-binding proteins (HSP73, calreticulin and CLIMP-63) and their potential for triggering caspases and Bcl-2 signalling cascades that are involved in aminoglycoside-induced cytotoxicity. We also discuss potential strategies to reduce aminoglycoside cytotoxicity, which are necessary for greater bactericidal efficacy during aminoglycoside pharmacotherapy.

Karasawa, Takatoshi; Steyger, Peter S.

2013-01-01

191

34 CFR 686.40 - Documenting the service obligation.  

Code of Federal Regulations, 2010 CFR

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

2009-07-01

192

48 CFR 2933.213 - Obligation to continue performance.  

Code of Federal Regulations, 2011 CFR

...Appeals 2933.213 Obligation to continue performance. The contracting officer must include the clause at FAR 52.233-1, Disputes (Alternate I), in contracts where continued performance is necessary pending resolution of any claim...

2011-10-01

193

48 CFR 333.213 - Obligation to continue performance.  

Code of Federal Regulations, 2012 CFR

...213 Obligation to continue performance. (a) The Contracting Officer shall use the Disputes clause at FAR 52.233-1 without the use of Alternate I. However, if the Contracting Officer determines that the Government's interest...

2012-10-01

194

48 CFR 2933.213 - Obligation to continue performance.  

Code of Federal Regulations, 2012 CFR

...Appeals 2933.213 Obligation to continue performance. The contracting officer must include the clause at FAR 52.233-1, Disputes (Alternate I), in contracts where continued performance is necessary pending resolution of any claim...

2012-10-01

195

48 CFR 333.213 - Obligation to continue performance.  

Code of Federal Regulations, 2011 CFR

...213 Obligation to continue performance. (a) The Contracting Officer shall use the Disputes clause at FAR 52.233-1 without the use of Alternate I. However, if the Contracting Officer determines that the Government's interest...

2011-10-01

196

22 CFR 231.07 - Fiscal Agent obligations.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

197

29 CFR 1986.102 - Obligations and prohibited acts.  

Code of Federal Regulations, 2013 CFR

...PROCEDURES FOR THE HANDLING OF RETALIATION COMPLAINTS UNDER THE EMPLOYEE PROTECTION PROVISION OF THE SEAMAN'S PROTECTION ACT (SPA), AS AMENDED Complaints, Investigations, Findings, and Preliminary Orders § 1986.102 Obligations and...

2013-07-01

198

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

199

7 CFR 1450.105 - Obligations of participant.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

200

24 CFR 576.203 - Obligation, expenditure, and payment requirements.  

Code of Federal Regulations, 2013 CFR

...SECRETARY FOR COMMUNITY PLANNING AND DEVELOPMENT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT COMMUNITY FACILITIES EMERGENCY SOLUTIONS GRANTS PROGRAM Award and Use of Funds § 576.203 Obligation, expenditure, and payment requirements. (a)...

2013-04-01

201

34 CFR 686.43 - Obligation to repay the grant.  

Code of Federal Regulations, 2013 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...

2013-07-01

202

28 CFR 0.147 - Certification of obligations.  

Code of Federal Regulations, 2013 CFR

...147 Certification of obligations. The...200(c): For the Federal Bureau of Investigation, the Assistant Director...Services Division; for the Bureau of Prisons, the Assistant...and Development; for Federal Prison...

2013-07-01

203

29 CFR 4043.20 - Post-Event filing obligation.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Post-Event filing obligation. 4043.20 Section...CORPORATION PLAN TERMINATIONS REPORTABLE EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events §...

2010-07-01

204

29 CFR 4043.20 - Post-Event filing obligation.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Post-Event filing obligation. 4043.20 Section...CORPORATION PLAN TERMINATIONS REPORTABLE EVENTS AND CERTAIN OTHER NOTIFICATION REQUIREMENTS Post-Event Notice of Reportable Events §...

2009-07-01

205

15 CFR 711.4 - Assistance in determining your obligations.  

Code of Federal Regulations, 2013 CFR

...SECURITY, DEPARTMENT OF COMMERCE CHEMICAL WEAPONS CONVENTION REGULATIONS GENERAL...obligations. (a) Determining if your chemical is subject to declaration, reporting...assistance in determining if your chemical is classified as a Schedule...

2013-01-01

206

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

207

25 CFR 226.9 - Rental and drilling obligations.  

Code of Federal Regulations, 2011 CFR

...MINERALS LEASING OF OSAGE RESERVATION LANDS FOR OIL AND GAS MINING Leasing Procedure, Rental and Royalty...Rental and drilling obligations. (a) Oil leases, gas leases, and combination oil and gas leases. Unless Lessee shall complete...

2011-04-01

208

13 CFR 500.213 - Termination of obligations.  

Code of Federal Regulations, 2012 CFR

... 500.213 Section 500.213 Business Credit and Assistance EMERGENCY OIL AND GAS GUARANTEED LOAN BOARD EMERGENCY OIL AND GAS GUARANTEED LOAN PROGRAM Oil and Gas Guaranteed Loans § 500.213 Termination of obligations....

2012-01-01

209

47 CFR 64.3001 - Obligation to transmit 911 calls.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) COMMON CARRIER SERVICES (CONTINUED) MISCELLANEOUS RULES RELATING TO COMMON CARRIERS Universal Emergency Telephone Number § 64.3001 Obligation to transmit 911 calls. All telecommunications carriers shall transmit all 911 calls...

2011-10-01

210

A Logical Analysis of the Relationship between Commitment and Obligation  

Microsoft Academic Search

In this paper, we analyze the relationship between commitment and obligation from a logical viewpoint. The principle of commitment\\u000a implying obligation is proven in a specific logic of action preference which is a generalization of Meyer's dynamic deontic\\u000a logic. In the proposed formalism, an agent's commitment to goals is considered as a special kind of action which can change\\u000a one's

Churn-Jung Liau

2001-01-01

211

The evolution of genomic instability in the obligate endosymbionts of whiteflies.  

PubMed

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

Sloan, Daniel B; Moran, Nancy A

2013-01-01

212

The Evolution of Genomic Instability in the Obligate Endosymbionts of Whiteflies  

PubMed Central

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

Sloan, Daniel B.; Moran, Nancy A.

2013-01-01

213

Unravelling the biology of macrophage infection by gene expression profiling of intracellular Salmonella enterica  

Microsoft Academic Search

Summary For intracellular pathogens such as Salmonellae , Mycobacteriae and Brucellae , infection requires adaptation to the intracellular environment of the phagocytic cell . The transition from extracellular to intravacuolar environment has been expected to involve a global modulation of bacterial gene expres- sion, but the precise events have been difficult to determine. We now report the complete transcrip- tional

Sofia Eriksson; Sacha Lucchini; Arthur Thompson; Mikael Rhen; Jay C. D. Hinton

2003-01-01

214

Intracellular Symbiosis in Insects  

Microsoft Academic Search

Many eukaryotic cells constitute the sole habitat for a vast and varied array of prokaryotic lineages (xcBuchner, 1965). These\\u000a intracellular associations have evolved repeatedly and have had major consequences for the diversification of both bacteria\\u000a and host. The magnitude of these consequences is immediately evident if one considers the examples of mitochondria and chloroplasts,\\u000a now widely acknowledged to be descended

Hajime Ishikawa

215

Bacterial vaginosis  

Microsoft Academic Search

Bacterial vaginosis, the most prevalent cause of vaginal discharge in the United States, is characterized microbiologically\\u000a by a shift in the vagina away from a lactobacillus-predominant flora and toward a predominantly anaerobic milieu. The cause\\u000a of bacterial vaginosis is unknown, but the epidemiology of the syndrome suggests that it is sexually associated. Bacterial\\u000a vaginosis has been associated with various complications,

Jane R. Schwebke

2000-01-01

216

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.

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

2012-01-01

217

Autophagy and bacterial infectious diseases  

PubMed Central

Autophagy is a housekeeping process that maintains cellular homeostasis through recycling of nutrients and degradation of damaged or aged cytoplasmic constituents. Over the past several years, accumulating evidence has suggested that autophagy can function as an intracellular innate defense pathway in response to infection with a variety of bacteria and viruses. Autophagy plays a role as a specialized immunologic effector and regulates innate immunity to exert antimicrobial defense mechanisms. Numerous bacterial pathogens have developed the ability to invade host cells or to subvert host autophagy to establish a persistent infection. In this review, we have summarized the recent advances in our understanding of the interaction between antibacterial autophagy (xenophagy) and different bacterial pathogens.

Yuk, Jae-Min; Yoshimori, Tamotsu

2012-01-01

218

Isolation and characterisation of obligately anaerobic, lipolytic bacteria from the rumen of red deer.  

PubMed

Two Gram-positive, obligately anaerobic, lipolytic bacteria, isolates LIP4 and LIP5, were obtained from the rumen contents of juvenile red deer. These mesophilic bacterial strains were capable of hydrolysing the neutral lipids, tallow, tripalmitin and oliver oil, into their constituent free long-chain fatty acid and glycerol moieties. The latter compound was dissimilated by both isolates, with isolate LIP4 producing propionate as the predominant product, while isolate LIP5 produced acetate, ethanol and succinate. The lactate-utilising isolate LIP4 grew on a limited range of saccharide substrates including glucose, fructose and ribose, and exhibited an unusual cell wall structure and morphology. The isolate LIP5 grew upon a wider range of saccharides, but was unable to use lactate as a substrate. Based upon phenotypic and 16S rRNA gene sequence analyses, isolate LIP4 clusters with species in the genus Propionibacterium, while isolate LIP5 is a member of clostridial cluster XIVa. PMID:9741118

Jarvis, G N; Strömpl, C; Moore, E R; Thiele, J H

1998-03-01

219

[Stearic acid methyl ether: a new extracellular metabolite of the obligate methylotrophic bacterium Methylophilus quaylei].  

PubMed

Methyl esters of fatty acids, free fatty acids, and hydrocarbons were found in the culture liquid and in the cellular lipids of the obligate methylotrophic bacterium Methylophilus quaylei under optimal growth conditions and osmotic stress. The main extracellular hydrophobic metabolite was methyl stearate. Exogenous free fatty acids C16-C18 and their methyl esters stimulated the M. quaylei growth and survivability, as well as production of exopolysaccharide under osmotic and oxidative stress, playing the role of growth factors and adaptogens. The order of hydrophobic supplements according to the ability to stimulate bacterial growth is C18 : 1 > C18 : 0 > C16 : 0 > methyl oleate > methyl stearate > no supplements > C14: 0 > C12 : 0. The mechanism underlying the protective action of fatty acids and their methyl esters is discussed. PMID:20391761

Terekhova, E A; Stepicheva, N A; Pshenichnikova, A B; Shvets, V I

220

Bacterial vaginosis  

Microsoft Academic Search

Bacterial vaginosis is the most common cause of vaginitis, affecting over 3 million women in the United States annually. Depopulation of lactobacilli from the normal vaginal flora and overgrowth of Gardnerella vaginalis and other anaerobic species are the presumed etiology. To date, no scientific evidence shows that bacterial vaginosis is a sexually transmitted disease. Malodorous vaginal discharge is the most

Jeff Wang

2000-01-01

221

Environmental and safety obligations of the Chemical Weapons Convention  

SciTech Connect

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

Tanzman, E.A.

1994-04-07

222

Nanovehicular Intracellular Delivery Systems  

PubMed Central

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

PROKOP, ALES; DAVIDSON, JEFFREY M.

2013-01-01

223

Metabolic Complementarity and Genomics of the Dual Bacterial Symbiosis of Sharpshooters  

PubMed Central

Mutualistic intracellular symbiosis between bacteria and insects is a widespread phenomenon that has contributed to the global success of insects. The symbionts, by provisioning nutrients lacking from diets, allow various insects to occupy or dominate ecological niches that might otherwise be unavailable. One such insect is the glassy-winged sharpshooter (Homalodisca coagulata), which feeds on xylem fluid, a diet exceptionally poor in organic nutrients. Phylogenetic studies based on rRNA have shown two types of bacterial symbionts to be coevolving with sharpshooters: the gamma-proteobacterium Baumannia cicadellinicola and the Bacteroidetes species Sulcia muelleri. We report here the sequencing and analysis of the 686,192–base pair genome of B. cicadellinicola and approximately 150 kilobase pairs of the small genome of S. muelleri, both isolated from H. coagulata. Our study, which to our knowledge is the first genomic analysis of an obligate symbiosis involving multiple partners, suggests striking complementarity in the biosynthetic capabilities of the two symbionts: B. cicadellinicola devotes a substantial portion of its genome to the biosynthesis of vitamins and cofactors required by animals and lacks most amino acid biosynthetic pathways, whereas S. muelleri apparently produces most or all of the essential amino acids needed by its host. This finding, along with other results of our genome analysis, suggests the existence of metabolic codependency among the two unrelated endosymbionts and their insect host. This dual symbiosis provides a model case for studying correlated genome evolution and genome reduction involving multiple organisms in an intimate, obligate mutualistic relationship. In addition, our analysis provides insight for the first time into the differences in symbionts between insects (e.g., aphids) that feed on phloem versus those like H. coagulata that feed on xylem. Finally, the genomes of these two symbionts provide potential targets for controlling plant pathogens such as Xylella fastidiosa, a major agroeconomic problem, for which H. coagulata and other sharpshooters serve as vectors of transmission.

Wu, Dongying; Daugherty, Sean C; Van Aken, Susan E; Pai, Grace H; Watkins, Kisha L; Khouri, Hoda; Tallon, Luke J; Zaborsky, Jennifer M; Dunbar, Helen E; Tran, Phat L; Moran, Nancy A

2006-01-01

224

The Chlamydia protease CPAF regulates host and bacterial proteins to maintain pathogen vacuole integrity and promote virulence  

PubMed Central

SUMMARY The obligate intracellular bacterial pathogen Chlamydia trachomatis injects numerous effector proteins into the epithelial cell cytoplasm to manipulate host functions important for bacterial survival. In addition, the bacterium secretes a serine protease, chlamydial protease-like activity factor (CPAF). Although several CPAF targets are reported, the significance of CPAF-mediated proteolysis is unclear due to the lack of specific CPAF inhibitors and the diversity of host targets. We report that CPAF also targets chlamydial effectors secreted early during the establishment of the pathogen-containing vacuole (“inclusion”). We designed a cell-permeable CPAF-specific inhibitory peptide and used it to determine that CPAF prevents superinfection by degrading early Chlamydia effectors translocated during entry into a pre-infected cell. Prolonged CPAF inhibition leads to loss of inclusion integrity and caspase-1-dependent death of infected epithelial cells. Thus, CPAF functions in niche protection, inclusion integrity and pathogen survival, making the development of CPAF-specific protease inhibitors an attractive anti-chlamydial therapeutic strategy.

Jorgensen, Ine; Bednar, Maria; Amin, Vishar; Davies, Beckley K.; Ting, Jenny P.Y.; McCafferty, Dewey; Valdivia, Raphael H.

2011-01-01

225

Exit Mechanisms of the Intracellular Bacterium Ehrlichia  

PubMed Central

Background The obligately intracellular bacterium Ehrlichia chaffeensis that resides in mononuclear phagocytes is the causative agent of human monocytotropic ehrlichiosis. Ehrlichia muris and Ixodes ovatus Ehrlichia (IOE) are agents of mouse models of ehrlichiosis. The mechanism by which Ehrlichia are transported from an infected host cell to a non-infected cell has not been demonstrated. Methodology/Principal Findings Using fluorescence microscopy and transmission and scanning electron microscopy, we demonstrated that Ehrlichia was transported through the filopodia of macrophages during early stages of infection. If host cells were not present in the vicinity of an Ehrlichia-infected cell, the leading edge of the filopodium formed a fan-shaped structure filled with the pathogen. Formation of filopodia in the host macrophages was inhibited by cytochalasin D and ehrlichial transport were prevented due to the absence of filopodia formation. At late stages of infection the host cell membrane was ruptured, and the bacteria were released. Conclusions/Significance Ehrlichia are transported through the host cell filopodium during initial stages of infection, but are released by host cell membrane rupture during later stages of infection.

Thomas, Sunil; Popov, Vsevolod L.; Walker, David H.

2010-01-01

226

The Interaction between IL-18 and IL-18R Limits the Magnitude of Protective Immunity and Enhances Pathogenic Responses Following Infection with Intracellular Bacteria  

PubMed Central

The binding of IL-18 to IL-18R? induces both pro-inflammatory and protective functions during infection, depending on the context in which it occurs. IL-18 is highly expressed in the liver of wild type (WT) C57BL/6 mice following lethal infection with highly virulent Ixodes Ovatus Ehrlichia (IOE), an obligate intracellular bacterium that causes acute fatal toxic shock-like syndrome. In this study, we found that IOE infection of IL-18R?-/- mice resulted in significantly less host cell apoptosis, decreased hepatic leukocyte recruitment, enhanced bacterial clearance and prolonged survival compared to infected WT mice, suggesting a pathogenic role of IL-18/IL-18R? in Ehrlichia-induced toxic shock. Although lack of IL-18R decreases the magnitude of IFN-? producing type-1 immune response, enhanced resistance of the IL-18R?-/- mice against Ehrlichia correlated with increased pro-inflammatory cytokines at sites of infection, decreased systemic IL-10 production, increased frequency of protective natural killer T (NKT) cells producing TNF-? and IFN-? and decreased frequency of pathogenic TNF-?-producing CD8+ T cells. Adoptive transfer of immune wild type CD8+ T cells increased bacterial burden in IL-18R?-/- mice following IOE infection. Furthermore, rIL-18 treatment of WT mice infected with mildly virulent Ehrlichia muris (EM) impaired bacterial clearance and enhanced liver injury. Finally, lack of IL-18R signal reduced dendritic cells (DCs) maturation and their TNF-? production, suggesting that IL-18 possibly promote the adaptive pathogenic immune responses against Ehrlichia via influencing T cell priming functions of DCs Together, these results suggest that the presence or absence of IL-18R signals governs the pathogenic versus protective immunity in a model of Ehrlichia-induced immunopathology.

Ghose, Purnima; Ali, Asim Q; Fang, Rong; Forbes, Digna; Ballard, Billy; Ismail, Nahed

2011-01-01

227

Nested bacterial boxes: nuclear and other intracellular compartments in planctomycetes.  

PubMed

Bacteria in the phylum Planctomycetes and some related phyla challenge our concept of the typical bacterium as consisting of cells without internal compartments or membrane-bounded organelles. Cells of all species of planctomycetes examined consist of at least two major compartments, and there are two other types of compartmentation in which a third compartment is formed either by a double-membrane envelope around the nucleoid in the case of the aerobic Gemmata obscuriglobus or by a single but potentially energized membrane in the case of the anaerobic ammonium-oxidizing anammox planctomycetes. We examine here the nature of these planctomycete compartments in relation to function and their relationship to the endomembranes defining them, and discuss the implications of the remarkable compartment-confined process of protein uptake in Gemmata, which resembles receptor- and clathrin-mediated endocytosis of eukaryotes. Planctomycetes have implications for our understanding of the evolution of membrane-bounded organelles, of endomembranes, transport across endomembranes and membrane trafficking, and for how the complexity of a eukaryote style of cell organization could have originated. PMID:23615198

Fuerst, John A; Sagulenko, Evgeny

2013-04-18

228

Azithromycin inhibition of intracellular Legionella micdadei.  

PubMed Central

Legionella micdadei is an intracellular parasite that is ingested, but not killed, by leukocytes. Within monocytes, the organism has been shown to grow 1.0 to 2.0 log10 units over 48 h (D. L. Weinbaum, R. R. Benner, J. N. Dowling, A. Alpern, A. W. Pasculle, and G. R. Donowitz, Infect. Immun. 46:68-73, 1984). Intracellular L. micdadei would appear to be a useful model in which to study the effect of antibiotics which accumulate intracellularly. Azithromycin, a newly introduced azalide, is highly concentrated within leukocytes and was therefore studied to determine its effect on a single strain of L. micdadei that had been ingested by human monocytes. Peripheral blood monocytes were allowed to ingest L. micdadei and extracellular, nonadherent organisms were subsequently removed by washing. Cells and cell-associated bacteria were then incubated at 0, 24, and 48 h in media with serial concentrations of azithromycin at sub-MIC levels (less than 1.0 microgram/ml). L. micdadei in cells not exposed to azithromycin grew 0.8 +/- 0.1 log10 units (mean +/- standard deviation) at 24 h and 1.7 +/- 0.4 log10 units at 48 h. At both 24 and 48 h, the lowest concentrations of azithromycin tested (0.02 microgram/ml) significantly inhibited bacterial growth in monocytes (P = 0.02). A stepwise inhibition of L. micdadei CFUs was noted with increasing azithromycin concentrations. In contrast, when cells were exposed to antibiotic before ingesting L. micdadei, a less effective antibacterial effect was noted. Under certain in vitro conditions, azithromycin is a potent agent against intracellular L. micdadei.

Donowitz, G R; Earnhardt, K I

1993-01-01

229

Facultative monogamy in obligate coral-dwelling hawkfishes (Cirrh tidae)  

Microsoft Academic Search

Obligate coral-dwelling hawkfishes have been hypothesized to be monogamous. This hypothesized mating system is at odds with what is known of those of other cirrhitids. Neocirrhites armatus, which inhabits Pocillopora spp. corals, and Oxycirrhites typus, which inhabits gorgonians and antipatharian corals, were examined for evidence of a monogamous mating system. Life history criteria that favor monogamy in reef fishes (Barlow

Terry J. Donaldson

1989-01-01

230

TAKING DUE CARE: MORAL OBLIGATIONS IN DUAL USE RESEARCH  

Microsoft Academic Search

ABSTRACTIn the past decade, the perception of a bioterrorist threat has increased and created a demand on life scientists to consider the potential security implications of dual use research. This article examines a selection of proposed moral obligations for life scientists that have emerged to meet these concerns and the extent to which they can be considered reasonable. It also

FRIDA KUHLAU; STEFAN ERIKSSON; KATHINKA EVERS; ANNA T. HÖGLUND

2008-01-01

231

18 CFR 367.2300 - Account 230, Asset retirement obligations.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Account 230, Asset retirement obligations...AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT...NATURAL GAS ACT Balance Sheet Chart of Accounts Other Noncurrent Liabilities §...

2013-04-01

232

45 CFR 1386.2 - Obligation of funds.  

Code of Federal Regulations, 2011 CFR

...property. (c) (1) The Protection and Advocacy System may elect to treat entry of...salaries of employees of the Protection and Advocacy agency. All funds made available for...Disabilities Councils and to the Protection and Advocacy System obligated under this...

2011-10-01

233

45 CFR 1386.2 - Obligation of funds.  

Code of Federal Regulations, 2012 CFR

...property. (c) (1) The Protection and Advocacy System may elect to treat entry of...salaries of employees of the Protection and Advocacy agency. All funds made available for...Disabilities Councils and to the Protection and Advocacy System obligated under this...

2012-10-01

234

Civic Engagement in Teacher Education: Activities or Obligation?  

ERIC Educational Resources Information Center

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

Erickson, Lynnette B.

2011-01-01

235

30 CFR 582.20 - Obligations and responsibilities of lessees.  

Code of Federal Regulations, 2013 CFR

...CONTINENTAL SHELF FOR MINERALS OTHER THAN OIL, GAS, AND SULPHUR Obligations and Responsibilities...precautions to prevent waste and damage to oil, gas, sulphur, and other OCS mineral-bearing...cause harm or damage to life (including fish and other aquatic life); to...

2013-07-01

236

Family Obligations in Micronesian Cultures: Implications for Educators  

ERIC Educational Resources Information Center

|Micronesian people, a new group of immigrants to the USA, have a strong system of responsibilities to family members that guides their priorities and actions. When family obligations clash with school priorities, conflicts can occur. I interviewed 26 adults to learn about the relationships and responsibilities of family members to each other in…

Ratliffe, Katherine T.

2010-01-01

237

Classification Revisions Reduce Reported Federal Development Obligations. InfoBrief.  

ERIC Educational Resources Information Center

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

Jankowski, John E.

238

76 FR 72645 - Calculation of Maximum Obligation Limitation  

Federal Register 2010, 2011, 2012, 2013

...Act. The Maximum Obligation Limitation (``MOL''), as set forth...amount that is equal to 10 percent of the total consolidated assets...amount that is equal to 90 percent of the fair value of the...amount that is equal to 10 percent of the total consolidated...

2011-11-25

239

77 FR 37554 - Calculation of Maximum Obligation Limitation  

Federal Register 2010, 2011, 2012, 2013

...Act. The Maximum Obligation Limitation (``MOL''), as set forth...amount that is equal to 10 percent of the total consolidated assets...amount that is equal to 90 percent of the fair value of the total...amount that is equal to 10 percent of the total consolidated...

2012-06-22

240

CHANGING OBLIGATIONS AND THE PSYCHOLOGICAL CONTRACT: A LONGITUDINAL STUDY  

Microsoft Academic Search

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

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

1994-01-01

241

Of community, organs and obligations: Routine salvage with a twist  

Microsoft Academic Search

This paper makes the assumption that organ transplantation is, under some conditions at least, a proper use of communal medical resources. Proceeding from this assumption, the author: (1) sketches the history of the problem; (2) briefly examines the prevalent models of communal structure and offers an alternate version; (3) discusses notions of justice and obligation derived from these different models;

Erich H. Loewy

1996-01-01

242

Specifying and monitoring economic environments using rights and obligations  

Microsoft Academic Search

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

Loizos Michael; David C. Parkes; Avi Pfeffer

2010-01-01

243

Developer's Concerns about Staff Retreat Create Opportunity and Obligation  

ERIC Educational Resources Information Center

This article deals with a staff developer's concerns about Bill Stewart's staff retreat, and how these concerns create opportunity and obligation. The author presents views from a superintendent and two staff developers on the staff retreat. Aside from these, the author talks about a superintendent named Darlene Preston, and her course of action.…

Killion, Joellen

2004-01-01

244

Ethical Obligations in a Tragedy of the Commons  

Microsoft Academic Search

When people use a resource without a co-ordinated plan the result is often a tragedy of the commons in which the resource is depleted. Many environmental resources display the characteristics of a developing tragedy of the commons. Many believe that each person is ethically obligated to reduce use of the commons to the sustainable level. I argue that this is

Baylor L. Johnson

2003-01-01

245

Oxidation of Inorganic Sulfur Compounds by Obligately Organotrophic Bacteria  

Microsoft Academic Search

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

D. Yu. Sorokin

2003-01-01

246

Simulation methods for risk analysis of collateralized debt obligations  

Microsoft Academic Search

Collateralized debt obligations (CDOs) are sophisticated financial products that offer a range of investments, known as tranches, at varying risk levels backed by a collateral pool typically consisting of corporate debt (bonds, loans, default swaps, etc.). The analysis of the risk-return properties of CDO tranches is complicated by the highly non-linear and time dependent relationship between the cash flows to

William J. Morokoff

2003-01-01

247

28 CFR 811.3 - Notice of obligation to register.  

Code of Federal Regulations, 2013 CFR

...sex offenders have an independent obligation to register. Persons who have been convicted or found not guilty by reason of insanity of a sex offense or who have been determined to be a sexual psychopath should report to CSOSA in order to ascertain...

2013-07-01

248

Classification Revisions Reduce Reported Federal Development Obligations. InfoBrief.  

ERIC Educational Resources Information Center

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

Jankowski, John E.

249

The Legal Obligation to Prosecute 'Rendition to Tor ture  

Microsoft Academic Search

The United States of America and Italy are currentl y in violation of binding legal obligations under the United Nations Convention against Torture and other cruel, inhuman or degrading treatment or punishment to investigate allegations of torture resulting from extraordinary rendition and to prose cute those individuals responsible. This article describes cases that aim to establish that (i) torture has

Elena Landriscina

250

The obligations and common ground structure of practical dialogues  

Microsoft Academic Search

In this paper a theory of dialogue structure of tas k oriented conversations and its associated tagging scheme are presented. The theory introduces two linguistic str uctures supporting the dialogue that, following tra ditional terminology, we call the obligations and common ground. The theory is illustrated with the detailed an alysis of a transaction. We also describe the empirical work

Luis Alberto Pineda; Varinia M. Estrada; Sergio Rafael Coria Olguin; James F. Allen

2007-01-01

251

Bacterial meningitis  

Microsoft Academic Search

Opinion statement  Initial empiric therapy for community-acquired bacterial meningitis should be based on the possibility that penicillin-resistant\\u000a pneumococci may be the etiologic organisms and, hence, should include a combination of third-generation cephalosporin (cefotaxime\\u000a or ceftriaxone) and vancomycin. Ampicillin should be included if the patient has predisposing factors that are associated\\u000a with a risk for infection with Listeria monocytogenes. Bacterial isolates from

Karen L. Roos

1999-01-01

252

Bacterial Cystitis  

Microsoft Academic Search

Urinary tract infection is one of the most common health problems affecting patients of all ages. It is the most common nosocomial\\u000a bacterial infection in the elderly. Women are especially prone to urinary tract infections (UTIs). Although prostatitis syndrome\\u000a accounts for 25% of male office visits for genitourinary tract infections, only 5% are attributed to a bacterial cause. Acute\\u000a cystitis

Joseph B. Abdelmalak; Jeannette M. Potts

253

Symbiosis and Insect Diversification: an Ancient Symbiont of Sap-Feeding Insects from the Bacterial Phylum Bacteroidetes  

Microsoft Academic Search

Several insect groups have obligate, vertically transmitted bacterial symbionts that provision hosts with nutrients that are limiting in the diet. Some of these bacteria have been shown to descend from ancient infections. Here we show that the large group of related insects including cicadas, leafhoppers, treehoppers, spittlebugs, and planthoppers host a distinct clade of bacterial symbionts. This newly described symbiont

Nancy A. Moran; Phat Tran; Nicole M. Gerardo

2005-01-01

254

Main Flaws of The Collateralized Debt Obligation‘s: Valuation Before And During The 2008\\/2009 Global Turmoil  

Microsoft Academic Search

As a result of the 2008 financial crisis, the world credit markets stalled significantly and raised the doubts of market participants and policymakers about the proper and fair valuation of financial derivatives and structured products such as collateralized debt obligations (CDOs). The aim of the paper is to contribute to the understanding of CDOs and shed light on CDO valuation

Petra Benešová; Petr Teply

2010-01-01

255

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

PubMed Central

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

Noore, Jabeen; Noore, Adly

2013-01-01

256

Chlamydia trachomatis co-opts GBF1 and CERT to acquire host sphingomyelin for distinct roles during intracellular development.  

PubMed

The obligate intracellular pathogen Chlamydia trachomatis replicates within a membrane-bound inclusion that acquires host sphingomyelin (SM), a process that is essential for replication as well as inclusion biogenesis. Previous studies demonstrate that SM is acquired by a Brefeldin A (BFA)-sensitive vesicular trafficking pathway, although paradoxically, this pathway is dispensable for bacterial replication. This finding suggests that other lipid transport mechanisms are involved in the acquisition of host SM. In this work, we interrogated the role of specific components of BFA-sensitive and BFA-insensitive lipid trafficking pathways to define their contribution in SM acquisition during infection. We found that C. trachomatis hijacks components of both vesicular and non-vesicular lipid trafficking pathways for SM acquisition but that the SM obtained from these separate pathways is being utilized by the pathogen in different ways. We show that C. trachomatis selectively co-opts only one of the three known BFA targets, GBF1, a regulator of Arf1-dependent vesicular trafficking within the early secretory pathway for vesicle-mediated SM acquisition. The Arf1/GBF1-dependent pathway of SM acquisition is essential for inclusion membrane growth and stability but is not required for bacterial replication. In contrast, we show that C. trachomatis co-opts CERT, a lipid transfer protein that is a key component in non-vesicular ER to trans-Golgi trafficking of ceramide (the precursor for SM), for C. trachomatis replication. We demonstrate that C. trachomatis recruits CERT, its ER binding partner, VAP-A, and SM synthases, SMS1 and SMS2, to the inclusion and propose that these proteins establish an on-site SM biosynthetic factory at or near the inclusion. We hypothesize that SM acquired by CERT-dependent transport of ceramide and subsequent conversion to SM is necessary for C. trachomatis replication whereas SM acquired by the GBF1-dependent pathway is essential for inclusion growth and stability. Our results reveal a novel mechanism by which an intracellular pathogen redirects SM biosynthesis to its replicative niche. PMID:21909260

Elwell, Cherilyn A; Jiang, Shaobo; Kim, Jung Hwa; Lee, Albert; Wittmann, Torsten; Hanada, Kentaro; Melancon, Paul; Engel, Joanne N

2011-09-01

257

18 CFR 292.310 - Procedures for utilities requesting termination of obligation to purchase from qualifying...  

Code of Federal Regulations, 2013 CFR

...obligation to purchase from qualifying facilities. 292.310 Section 292.310 ...Cogeneration and Small Power Production Facilities Under Section 210 of the Public Utility...obligation to purchase from qualifying facilities. (a) An electric utility...

2013-04-01

258

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

259

Drug Control: Status of Obligations for Fiscal Year 1990 DOD Counternarcotics Funds.  

National Technical Information Service (NTIS)

This fact sheet responds to your request for information on the status of obligations for the fiscal year 1990 Department of Defense (DOD) counternarcotics appropriation of $450 million. Specifically, we (1) compared the obligation rates for counternarcot...

1990-01-01

260

2 CFR 376.370 - What are the obligations of Medicare carriers and intermediaries?  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false What are the obligations of Medicare carriers and intermediaries? 376.370...376.370 What are the obligations of Medicare carriers and intermediaries? Because Medicare carriers, intermediaries and other...

2013-01-01

261

75 FR 62634 - Proposed Information Collection (Obligation to Report Factors Affecting Entitlement) Activity...  

Federal Register 2010, 2011, 2012, 2013

...Information Collection (Obligation to Report Factors Affecting Entitlement) Activity: Comment...technology. Title: Obligation to Report Factors Affecting Entitlement (38 CFR 3.204...must report changes in their entitlement factors. Individual factors such as...

2010-10-12

262

78 FR 46418 - Proposed Information Collection (Obligation To Report Factors Affecting Entitlement) Activity...  

Federal Register 2010, 2011, 2012, 2013

...Information Collection (Obligation To Report Factors Affecting Entitlement) Activity; Comment...technology. Title: Obligation to Report Factors Affecting Entitlement (38 CFR 3.204...must report changes in their entitlement factors. Individual factors such as...

2013-07-31

263

75 FR 80114 - Agency Information Collection (Obligation To Report Factors Affecting Entitlement) Activity Under...  

Federal Register 2010, 2011, 2012, 2013

...Information Collection (Obligation To Report Factors Affecting Entitlement) Activity Under...INFORMATION: Title: Obligation to Report Factors Affecting Entitlement (38 CFR 3.204...must report changes in their entitlement factors. Individual factors such as...

2010-12-21

264

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

265

24 CFR 982.633 - Homeownership option: Continued assistance requirements; Family obligations.  

Code of Federal Regulations, 2013 CFR

...option: Continued assistance requirements; Family obligations. 982.633 Section 982...option: Continued assistance requirements; Family obligations. (a) Occupancy of home...Homeownership assistance may only be paid while the family is residing in the home. If the...

2013-04-01

266

18 CFR 367.2270 - Account 227, Obligations under capital lease-Non-current.  

Code of Federal Regulations, 2013 CFR

... Account 227, Obligations under capital lease-Non-current. 367.2270...ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS... Account 227, Obligations under capital leaseâNon-current....

2013-04-01

267

18 CFR 367.2430 - Account 243, Obligations under capital leases-Current.  

Code of Federal Regulations, 2013 CFR

... Account 243, Obligations under capital leases-Current. 367.2430...ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS... Account 243, Obligations under capital leasesâCurrent. This...

2013-04-01

268

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

Code of Federal Regulations, 2010 CFR

...false Statutory obligation of third party payer to pay. 220.2 Section...MISCELLANEOUS COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR...220.2 Statutory obligation of third party payer to pay. (a) Basic...

2009-07-01

269

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

Code of Federal Regulations, 2010 CFR

...false Statutory obligation of third party payer to pay. 220.2 Section...MISCELLANEOUS COLLECTION FROM THIRD PARTY PAYERS OF REASONABLE CHARGES FOR...220.2 Statutory obligation of third party payer to pay. (a) Basic...

2010-07-01

270

45 CFR 303.31 - Securing and enforcing medical support obligations.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Securing and enforcing medical support obligations. 303.31...303.31 Securing and enforcing medical support obligations. (a) For purposes of this section: (1) Cash medical support means an amount...

2012-10-01

271

18 CFR 292.303 - Electric utility obligations under this subpart.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Electric utility obligations under this subpart...AND COGENERATION Arrangements Between Electric Utilities and Qualifying Cogeneration...Policies Act of 1978 § 292.303 Electric utility obligations under this...

2013-04-01

272

10 CFR 40.56 - Restrictions on the use of Australian-obligated source material.  

Code of Federal Regulations, 2013 CFR

...Australian-obligated source material. 40.56 Section 40.56 Energy NUCLEAR REGULATORY...DOMESTIC LICENSING OF SOURCE MATERIAL Transfer...Peaceful Uses of Nuclear Energy, dated 2010, Australian-obligated source material...

2013-01-01

273

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

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Obligations of Funding Corporation; no adverse claims. ...DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION BOOK-ENTRY PROCEDURE § 1511.5 Obligations of Funding Corporation; no adverse...

2013-01-01

274

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

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Obligations of Transmission Providers and Responsible Parties...SYSTEMS § 37.5 Obligations of Transmission Providers and Responsible Parties. (a) Each Transmission Provider is required to provide...

2013-04-01

275

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

Federal Register 2010, 2011, 2012, 2013

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

2013-10-23

276

Moral obligations of nurses and physicians in neonatal end-of-life care  

PubMed Central

The aim of this study was to explore the obligations of nurses and physicians in providing end-of-life care. Nineteen nurses and 11 physicians from a single newborn intensive care unit participated. Using content analysis, an overarching obligation of creating the best possible experience for infants and parents was identified, within which two categories of obligations (decision making and the end of life itself) emerged. Obligations in decision making included talking to parents and timing withdrawal. End-of-life obligations included providing options, preparing parents, being with, advocating, creating peace and normalcy, and providing comfort. Nurses and physicians perceived obligations in both categories, although nurse obligations centered on the end of life while physician obligations focused on decision making. The findings demonstrate that, although the ultimate goal is shared by both disciplines, the paths to achieving that goal are often different. This has important implications for collaboration, communication, and improving the end of life.

Epstein, Elizabeth Gingell

2013-01-01

277

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

278

43 CFR 9.11 - What are the Secretary's obligations in interstate situations?  

Code of Federal Regulations, 2010 CFR

...Secretary's obligations in interstate situations? 9.11 Section 9.11 Public Lands: Interior Office of the Secretary...DEPARTMENT OF THE INTERIOR PROGRAMS AND ACTIVITIES § 9.11 What are the Secretary's obligations in...

2009-10-01

279

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

280

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

281

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

282

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

283

43 CFR 9.5 - What is the Secretary's obligation with respect to Federal interagency coordination?  

Code of Federal Regulations, 2012 CFR

...Secretary's obligation with respect to Federal interagency coordination? 9.5 Section 9.5 Public Lands: Interior...PROGRAMS AND ACTIVITIES § 9.5 What is the Secretary's obligation with respect to Federal interagency...

2012-10-01

284

43 CFR 9.5 - What is the Secretary's obligation with respect to Federal interagency coordination?  

Code of Federal Regulations, 2011 CFR

...Secretary's obligation with respect to Federal interagency coordination? 9.5 Section 9.5 Public Lands: Interior...PROGRAMS AND ACTIVITIES § 9.5 What is the Secretary's obligation with respect to Federal interagency...

2011-10-01

285

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

Federal Register 2010, 2011, 2012, 2013

...3133-AEOO Loan Participations; Purchase, Sale and Pledge of Eligible Obligations; Purchase...titled Loan Participations; Purchase, Sale and Pledge of Eligible Obligations; Purchase...FURTHER INFORMATION CONTACT: Pamela Yu, Staff Attorney, Office of General...

2013-07-09

286

26 CFR 15a.453-2 - Installment obligations received as liquidating distribution. [Reserved  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Installment obligations received as liquidating distribution...TEMPORARY INCOME TAX REGULATIONS UNDER THE INSTALLMENT SALES REVISION ACT § 15a.453-2 Installment obligations received as liquidating...

2010-04-01

287

26 CFR 15a.453-2 - Installment obligations received as liquidating distribution. [Reserved  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Installment obligations received as liquidating distribution...TEMPORARY INCOME TAX REGULATIONS UNDER THE INSTALLMENT SALES REVISION ACT § 15a.453-2 Installment obligations received as liquidating...

2009-04-01

288

Bacterial rheotaxis  

PubMed Central

The motility of organisms is often directed in response to environmental stimuli. Rheotaxis is the directed movement resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates, and spermatozoa. Using carefully controlled microfluidic flows, we show that rheotaxis also occurs in bacteria. Excellent quantitative agreement between experiments with Bacillus subtilis and a mathematical model reveals that bacterial rheotaxis is a purely physical phenomenon, in contrast to fish rheotaxis but in the same way as sperm rheotaxis. This previously unrecognized bacterial taxis results from a subtle interplay between velocity gradients and the helical shape of flagella, which together generate a torque that alters a bacterium's swimming direction. Because this torque is independent of the presence of a nearby surface, bacterial rheotaxis is not limited to the immediate neighborhood of liquid–solid interfaces, but also takes place in the bulk fluid. We predict that rheotaxis occurs in a wide range of bacterial habitats, from the natural environment to the human body, and can interfere with chemotaxis, suggesting that the fitness benefit conferred by bacterial motility may be sharply reduced in some hydrodynamic conditions.

Marcos; Fu, Henry C.; Powers, Thomas R.; Stocker, Roman

2012-01-01

289

Revisiting intracellular calcium signaling semantics  

Microsoft Academic Search

Cells use intracellular free calcium concentration changes for signaling. Signal encoding occurs through both spatial and temporal modulation of the free calcium concentration. The encoded message is detected by an ensemble of intracellular sensors forming the family of calcium-binding proteins (CaBPs) which must faithfully translate the message using a new syntax that is recognized by the cell. The cell is

Jacques Haiech; Emilie Audran; Marie Fève; Raoul Ranjeva; Marie-Claude Kilhoffer

2011-01-01

290

The ubiquitin ligase parkin mediates resistance to intracellular pathogens.  

PubMed

Ubiquitin-mediated targeting of intracellular bacteria to the autophagy pathway is a key innate defence mechanism against invading microbes, including the important human pathogen Mycobacterium tuberculosis. However, the ubiquitin ligases responsible for catalysing ubiquitin chains that surround intracellular bacteria are poorly understood. The parkin protein is a ubiquitin ligase with a well-established role in mitophagy, and mutations in the parkin gene (PARK2) lead to increased susceptibility to Parkinson's disease. Surprisingly, genetic polymorphisms in the PARK2 regulatory region are also associated with increased susceptibility to intracellular bacterial pathogens in humans, including Mycobacterium leprae and Salmonella enterica serovar Typhi, but the function of parkin in immunity has remained unexplored. Here we show that parkin has a role in ubiquitin-mediated autophagy of M. tuberculosis. Both parkin-deficient mice and flies are sensitive to various intracellular bacterial infections, indicating parkin has a conserved role in metazoan innate defence. Moreover, our work reveals an unexpected functional link between mitophagy and infectious disease. PMID:24005326

Manzanillo, Paolo S; Ayres, Janelle S; Watson, Robert O; Collins, Angela C; Souza, Gianne; Rae, Chris S; Schneider, David S; Nakamura, Ken; Shiloh, Michael U; Cox, Jeffery S

2013-09-04

291

Saprophytic intracellular rhizobia in alfalfa nodules.  

PubMed

In indeterminate alfalfa nodules, the establishment of the senescent zone IV, in which both symbionts undergo simultaneous degeneration, has been considered, until now, as the end point of the symbiotic interaction. However, we now describe an additional zone, zone V, proximal to the senescent zone IV and present in alfalfa nodules more than 6 weeks old. In zone V, a new round of bacterial release occurs from remaining infection threads, leading to the reinvasion of plant cells that have completely senesced. These intracellular rhizobia are rod shaped and do not display the ultrastructural differentiation features of bacteroids observed in the more distal zones of the nodule. Interestingly, we have found that oxygen is available in zone V at a concentration compatible with both bacterial development and nitrogen fixation gene expression in newly released rhizobia. However, this expression is not correlated with acetylene reduction. Moreover, the pattern of nifH expression in this zone, as well as new data relating to expression in zone II, strongly suggest that nifH transcription in the nodule is under the control of a negative regulator in addition to oxygen. Our results support the conclusion that zone V is an ecological niche where intracellular rhizobia take advantage of the interaction for their exclusive benefit and live as parallel saprophytic partners. The demonstration of such an advantage for rhizobia in nodules was the missing evidence that Rhizobium-legume interactions are indeed symbiotic and, in particular, suggests that benefits to the two partners are associated with different developmental stages within the nodule. PMID:11059487

Timmers, A C; Soupène, E; Auriac, M C; de Billy, F; Vasse, J; Boistard, P; Truchet, G

2000-11-01

292

Bacterial and archaeal flagella as prokaryotic motility organelles.  

PubMed

The properties and molecular organization of flagella--the bacterial and archaeal motility organelles--are reviewed. The organization of these functional motility elements of prokaryotic organisms belonging to different kingdoms is compared. A mechanism for both in vivo and in vitro assembly of bacterial flagellum filaments (BFFs) is discussed, and similarity is supposed between flagellin and actin with regard to their polymeric forms (BFF and F-actin). Our own data on intracellular fixation of the Halobacterium salinarium flagellum are presented. Comparative characteristics of intracellular fixation of bacterial and archaeal flagella are also described. PMID:15627373

Metlina, A L

2004-11-01

293

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

294

Embedded cosmopolitanism and the politics of obligation: the Ghanaian diaspora and development  

Microsoft Academic Search

The author analyses how identities and obligations operate within the spaces of transnational communities and how this affects development. Within spatially diffuse communities, identities are fluid and overlapping, as are the obligations to multiple others—be that kin, ethnic group, or nation—in different localities. The author is concerned with the institutions through which these identities are formed and obligations are fulfilled.

Giles Mohan

2006-01-01

295

31 CFR 223.13 - Full penalty of the obligation regarded as the liability; exceptions.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Full penalty of the obligation regarded as...BUSINESS WITH THE UNITED STATES § 223.13 Full penalty of the obligation regarded as the...limitation prescribed in this part, the full penalty of the obligation will be...

2013-07-01

296

Implementing Collective Obligations in Human-Agent Teams Using KAoS Policies  

Microsoft Academic Search

Obligations can apply to individuals, either severally or collectively. When applied severally, each individual or member of a team is independently responsible to fulfill the obligation. When applied collectively, it is the group as a whole that becomes responsible, with individual members sharing the obligation. In this paper, we present several variations of teamwork models involving the performance of collective

Jurriaan van Diggelen; Jeffrey M. Bradshaw; Matthew Johnson; Andrzej Uszok; Paul J. Feltovich

2009-01-01

297

Nutrient availability induces contrasting allocation and starch formation in resprouting and obligate seeding shrubs  

Microsoft Academic Search

Summary 1. Woody plant responses to crown removal in fire-prone vegetation are of two types: resprouting (resprouters) or killed (obligate seeders). Obligate seeders maximize their fitness by ensuring they are reproductively mature before the next fire; resprouters invest in structures that increase their chance of surviving the next fire. 2. We tested whether seven congeneric pairs of resprouter and obligate

K. J. E. KNOX; P. J. CLARKE

2005-01-01

298

The Genome Sequence of the Obligately Chemolithoautotrophic, Facultatively Anaerobic Bacterium Thiobacillus denitrificans  

PubMed Central

The complete genome sequence of Thiobacillus denitrificans ATCC 25259 is the first to become available for an obligately chemolithoautotrophic, sulfur-compound-oxidizing, ?-proteobacterium. Analysis of the 2,909,809-bp genome will facilitate our molecular and biochemical understanding of the unusual metabolic repertoire of this bacterium, including its ability to couple denitrification to sulfur-compound oxidation, to catalyze anaerobic, nitrate-dependent oxidation of Fe(II) and U(IV), and to oxidize mineral electron donors. Notable genomic features include (i) genes encoding c-type cytochromes totaling 1 to 2 percent of the genome, which is a proportion greater than for almost all bacterial and archaeal species sequenced to date, (ii) genes encoding two [NiFe]hydrogenases, which is particularly significant because no information on hydrogenases has previously been reported for T. denitrificans and hydrogen oxidation appears to be critical for anaerobic U(IV) oxidation by this species, (iii) a diverse complement of more than 50 genes associated with sulfur-compound oxidation (including sox genes, dsr genes, and genes associated with the AMP-dependent oxidation of sulfite to sulfate), some of which occur in multiple (up to eight) copies, (iv) a relatively large number of genes associated with inorganic ion transport and heavy metal resistance, and (v) a paucity of genes encoding organic-compound transporters, commensurate with obligate chemolithoautotrophy. Ultimately, the genome sequence of T. denitrificans will enable elucidation of the mechanisms of aerobic and anaerobic sulfur-compound oxidation by ?-proteobacteria and will help reveal the molecular basis of this organism's role in major biogeochemical cycles (i.e., those involving sulfur, nitrogen, and carbon) and groundwater restoration.

Beller, Harry R.; Chain, Patrick S. G.; Letain, Tracy E.; Chakicherla, Anu; Larimer, Frank W.; Richardson, Paul M.; Coleman, Matthew A.; Wood, Ann P.; Kelly, Donovan P.

2006-01-01

299

Deconfounding distance effects in judgments of moral obligation.  

PubMed

A heavily disputed question of moral philosophy is whether spatial distance between agent and victim is normatively relevant for the degree of obligation to help strangers in need. In this research, we focus on the associated descriptive question whether increased distance does in fact reduce individuals' sense of helping obligation. One problem with empirically answering this question is that physical proximity is typically confounded with other factors, such as informational directness, shared group membership, or increased efficaciousness. In a series of 5 experiments, we show that distance per se does not influence people's moral intuitions when it is isolated from such confounds. We support our claims with both frequentist and Bayesian statistics. We relate these findings to philosophical arguments concerning the normative relevance of distance and to psychological theories linking distance cues to higher level social cognition. The effects of joint versus separate evaluation paradigms on moral judgments are also discussed. PMID:22686846

Nagel, Jonas; Waldmann, Michael R

2012-06-11

300

Bacterial iron homeostasis.  

PubMed

Iron is essential to virtually all organisms, but poses problems of toxicity and poor solubility. Bacteria have evolved various mechanisms to counter the problems imposed by their iron dependence, allowing them to achieve effective iron homeostasis under a range of iron regimes. Highly efficient iron acquisition systems are used to scavenge iron from the environment under iron-restricted conditions. In many cases, this involves the secretion and internalisation of extracellular ferric chelators called siderophores. Ferrous iron can also be directly imported by the G protein-like transporter, FeoB. For pathogens, host-iron complexes (transferrin, lactoferrin, haem, haemoglobin) are directly used as iron sources. Bacterial iron storage proteins (ferritin, bacterioferritin) provide intracellular iron reserves for use when external supplies are restricted, and iron detoxification proteins (Dps) are employed to protect the chromosome from iron-induced free radical damage. There is evidence that bacteria control their iron requirements in response to iron availability by down-regulating the expression of iron proteins during iron-restricted growth. And finally, the expression of the iron homeostatic machinery is subject to iron-dependent global control ensuring that iron acquisition, storage and consumption are geared to iron availability and that intracellular levels of free iron do not reach toxic levels. PMID:12829269

Andrews, Simon C; Robinson, Andrea K; Rodríguez-Quiñones, Francisco

2003-06-01

301

Evolution of obligate pollination mutualism in New Caledonian Phyllanthus (Euphorbiaceae)  

Microsoft Academic Search

About half a dozen obligate pollination mutualisms between plants and their seed-consuming pollinators are currently recognized, including fig-fig wasp, yucca-yucca moth, and the recently discoveredGlochidion tree-Epicephala moth mutualisms. A common principle among these interactions is that the pollinators consume only a limited amount of the seed crop within a developing fruit (or fig in the case of fig-fig wasp mutualism),

ATSUSHI KAWAKITA; MAKOTO KATO

2004-01-01

302

Losing the desire: selection can promote obligate asexuality.  

PubMed

Whilst parthenogenesis has evolved multiple times from sexual invertebrate and vertebrate lineages, the drivers and consequences of the sex-asex transition remain mostly uncertain. A model by Stouthamer et al. recently published in BMC Evolutionary Biology shows a pathway by which obligate asexuality could be selected for following endosymbiont infection. See research article http://www.biomedcentral.com/1471-2148/10/229. PMID:20687906

King, Kayla C; Hurst, Gregory D D

2010-07-28

303

An Empirical Analysis of the Pricing of Collateralized Debt Obligations  

Microsoft Academic Search

We use the information in collateralized debt obligations (CDO) prices to study market expectations about how corporate defaults cluster. A three-factor portfolio credit model explains virtually all of the time-series and cross-sectional variation in an extensive data set of CDX index tranche prices. Tranches are priced as if losses of 0.4%, 6%, and 35% of the portfolio occur with expected

FRANCIS A. LONGSTAFF; ARVIND RAJAN

2008-01-01

304

Genetic variability in obligate apomicts of the genus Taraxacum  

Microsoft Academic Search

To test whether obligate apomicts can generate genetic variability, the only valid procedure is to investigate heritable variation\\u000a amongst the offspring of fully agamospermous mothers. Among plants, most reports have been forTaraxacum, and this review concentrates on this genus, although there are many analogous reports for animals. InTaraxacum, within-family variation is commonly found at the levels of ploidy, aneuploidy, recombination

A. John Richards

1996-01-01

305

Automating the Extraction of Rights and Obligations for Regulatory Compliance  

Microsoft Academic Search

Government regulations are increasingly affecting the security, privacy and governance of information systems in the United\\u000a States, Europe and elsewhere. Consequently, companies and software developers are required to ensure that their software systems\\u000a comply with relevant regulations, either through design or re-engineering. We previously proposed a methodology for extracting\\u000a stakeholder requirements, called rights and obligations, from regulations. In this paper,

Nadzeya Kiyavitskaya; Nicola Zeni; Travis D. Breaux; Annie I. Antón; James R. Cordy; Luisa Mich; John Mylopoulos

2008-01-01

306

Clinical findings in obligate carriers of type I Usher syndrome  

SciTech Connect

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

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

1995-11-20

307

A novel obligate cultivation mutualism between damselfish and Polysiphonia algae.  

PubMed

In cultivation mutualisms, farming animals prepare fields for cultivars, enhance their growth and harvest them. For example, in terrestrial ecosystems, plant-herbivore cultivation mutualisms arose between humans and their crops only relatively recently. We discovered an obligate cultivation mutualism between a damselfish and an alga in a coral reef ecosystem. The damselfish, Stegastes nigricans, manages algal farms through territorial defence against the invading grazers and through weeding of unpalatable algae. As a result, the algal farms of S. nigricans are dominated by one species, Polysiphonia sp. We performed an exhaustive survey of algal assemblages inside and outside the territories of five damselfish species around the Ryukyu Islands, Japan, using molecular and morphological characteristics. Polysiphonia sp. 1 grew exclusively inside the farms of S. nigricans, and never elsewhere. Since only Polysiphonia sp. 1 is harvested and consumed by the damselfish as a staple food, this interdependent relationship is an obligate cultivation mutualism. This is the first record of an obligate plant-herbivore cultivation mutualism in a marine ecosystem. Our data also suggest that three other Polysiphonia species are facultatively mutual with, commensal with, or parasitic on other damselfish species. PMID:17148297

Hata, Hiroki; Kato, Makoto

2006-12-22

308

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.

Junker, Robert R.; Bluthgen, Nico

2010-01-01

309

A novel obligate cultivation mutualism between damselfish and Polysiphonia algae  

PubMed Central

In cultivation mutualisms, farming animals prepare fields for cultivars, enhance their growth and harvest them. For example, in terrestrial ecosystems, plant–herbivore cultivation mutualisms arose between humans and their crops only relatively recently. We discovered an obligate cultivation mutualism between a damselfish and an alga in a coral reef ecosystem. The damselfish, Stegastes nigricans, manages algal farms through territorial defence against the invading grazers and through weeding of unpalatable algae. As a result, the algal farms of S. nigricans are dominated by one species, Polysiphonia sp. We performed an exhaustive survey of algal assemblages inside and outside the territories of five damselfish species around the Ryukyu Islands, Japan, using molecular and morphological characteristics. Polysiphonia sp. 1 grew exclusively inside the farms of S. nigricans, and never elsewhere. Since only Polysiphonia sp. 1 is harvested and consumed by the damselfish as a staple food, this interdependent relationship is an obligate cultivation mutualism. This is the first record of an obligate plant–herbivore cultivation mutualism in a marine ecosystem. Our data also suggest that three other Polysiphonia species are facultatively mutual with, commensal with, or parasitic on other damselfish species.

Hata, Hiroki; Kato, Makoto

2006-01-01

310

The Type IV Secretion System of Sinorhizobium meliloti Strain 1021 Is Required for Conjugation but Not for Intracellular Symbiosis?  

PubMed Central

The type IV secretion system (T4SS) of the plant intracellular symbiont Sinorhizobium meliloti 1021 is required for conjugal transfer of DNA. However, it is not required for host invasion and persistence, unlike the T4SSs of closely related mammalian intracellular pathogens. A comparison of the requirement for a bacterial T4SS in plant versus animal host invasion suggests an important difference in the intracellular niches occupied by these bacteria.

Jones, Kathryn M.; Lloret, Javier; Daniele, Joseph R.; Walker, Graham C.

2007-01-01

311

Cytokine Expression in Response to Bacterial Antigens in Preterm and Term Infant Cord Blood Monocytes  

Microsoft Academic Search

Background: Neonatal susceptibility to bacterial infection is associated with an immature immune system, but the role of different bacterial antigens in specific responses is largely unknown. Objective: To evaluate differences in intracellular cytokine response to physiologically relevant bacterial antigens in term and preterm infants as compared with adults. Methods: Cord blood samples from preterm and term neonates and adult peripheral

A. M. Francesca Tatad; Mirjana Nesin; John Peoples; Sandy Cheung; Hong Lin; Cristina Sison; Jeffrey Perlman; Susanna Cunningham-Rundles

2008-01-01

312

Bacterial vaginosis  

Microsoft Academic Search

Bacterial vaginosis is a common cause of abnormal discharge in women of child-bearing age. It is present in 10–20% women in the UK, and may recur or regress spontaneously. It is not regarded as an STI because it can occur in virgin women, but it is more common in sexually active women. Other associations include smoking, partner change, having a

Phillip Hay

2005-01-01

313

Bacterial Biofertilizers  

Microsoft Academic Search

Many bacteria and fungi can enhance plant growth. The present review is limited to plant growth promoting rhizobacteria (PGPR). However, it includes endophytic bacteria that show plant growth enhancing activity as well. Also the best studied bacterial mechanisms of plant growth promotion are discussed, with a special emphasis on biological nitrogen fixation and synthesis of phytohormones, including less understood mechanisms

LUIS E. FUENTES-RAMIREZ; Jesus Caballero-Mellado

314

Bacterial proteases and virulence.  

PubMed

Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated with the proteases either encoded within the same polypeptide or on separate subunits. In contrast, substrate recognition by extracellular proteases is less selective and therefore these enzymes are generally expressed as zymogens to prevent premature proteolytic activity that would be detrimental to the cell. These extracellular proteases are activated in complex cascades involving auto-processing and proteolytic maturation. Thus, proteolysis has been adopted by bacterial pathogens at multiple levels to ensure the success of the pathogen in contact with the human host. PMID:23479441

Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

2013-01-01

315

Coxiella subversion of intracellular host signaling.  

PubMed

Coxiella burnetii is a highly infectious bacterial pathogen that replicates in a specialized vacuole inside eukaryotic cells. Due to a prolonged growth cycle, Coxiella continuously manipulates cellular processes to generate this parasitophorous vacuole (PV) and promote host cell viability. Here, we discuss recent findings that indicate Coxiella modulates several host signaling pathways to influence survival and ensure intracellular replication. The pathogen actively inhibits apoptotic cell death and activates the pro-survival kinases Akt and Erk1/2 to promote host viability. Coxiella's anti-apoptotic activity also involves the interface between autophagy and apoptosis, which is regulated by the interaction of autophagy-related Beclin-1 and anti-apoptotic Bcl-2. Additionally, Coxiella requires host kinase activity for PV biogenesis and maintenance. Thus, signaling modulation by Coxiella is critical for multiple aspects of host cell parasitism. Collectively, recent signaling studies have enhanced our understanding of the unique Coxiella-host cell interaction. Identification of bacterial factors that regulate signaling events will further our ability to model this intriguing infectious process. PMID:22711630

Hussain, S Kauser; Voth, Daniel E

2012-01-01

316

Efficient Procedure for Purification of Obligate Intracellular Wolbachia pipientis and Representative Amplification of Its Genome by Multiple-Displacement Amplification  

PubMed Central

Bacteria belonging to the genus Wolbachia are obligatorymicroendocytobionts that infect a variety of arthropods and a majority of filarial nematode species, where they induce reproductive alterations or establish a mutualistic symbiosis. Although two whole genome sequences of Wolbachia pipientis, for strain wMel from Drosophila melanogaster and strain wBm from Brugia malayi, have been fully completed and six other genome sequencing projects are ongoing (http://www.genomesonline.org/index.cgi?want=Prokaryotic+Ongoin), genetic analyses of these bacteria are still scarce, mainly due to the inability to cultivate them outside of eukaryotic cells. Usually, a large amount of host tissue (a thousand individuals, or about 10 g) is required in order to purify Wolbachia and extract its DNA, which is often recovered in small amounts and contaminated by host cell DNA, thus hindering genomic studies. In this report, we describe an efficient and reliable procedure to representatively amplify the Wolbachia genome by multiple-displacement amplification from limited infected host tissue (0.2 g or 2 × 107 cells). We obtained sufficient amounts (8 to 10 ?g) of DNA of suitable quality for genomic studies, and we demonstrated that the amplified DNA contained all of the Wolbachia loci targeted. In addition, our data indicated that the genome of strain wRi, an obligatory endosymbiont of Drosophila simulans, shares a similar overall architecture with its relative strain wMel.

Mavingui, Patrick; Tran Van, Van; Labeyrie, Estelle; Rances, Edwige; Vavre, Fabrice; Simonet, Pascal

2005-01-01

317

Rickettsial Outer-Membrane Protein B (rOmpB) Mediates Bacterial Invasion through Ku70 in an Actin, c-Cbl, Clathrin and Caveolin 2-Dependent Manner  

PubMed Central

Summary Rickettsia conorii, an obligate intracellular tick-borne pathogen and the causative agent of Mediterranean spotted fever, binds to and invades non-phagocytic mammalian cells. Previous work identified Ku70 as a mammalian receptor involved in the invasion process and identified the rickettsial autotransporter protein, rOmpB, as a ligand; however, little is known about the role of Ku70-rOmpB interactions in the bacterial invasion process. Using an E. coli heterologous expression system, we show here that rOmpB mediates attachment to mammalian cells and entry in a Ku70-dependent process. A purified recombinant peptide corresponding to the rOmpB passenger domain interacts with Ku70 and serves as a competitive inhibitor of adherence. We observe that rOmpB-mediated infection culminates in actin recruitment at the bacterial foci, and that this entry process relies in part on actin polymerization likely imparted through protein tyrosine kinase and PI3-kinase-dependent activities and microtubule stability. Small-interfering RNA (siRNA) studies targeting components of the endocytic pathway reveal that entry by rOmpB is dependent on c-Cbl, clathrin and caveolin-2. Together, these results illustrate that rOmpB is sufficient to mediate Ku70-dependent invasion of mammalian cells and that clathrin- and caveolin-dependent endocytic events likely contribute to the internalization process.

Chan, Yvonne G.Y.; Cardwell, Marissa M.; Hermanas, Timothy M.; Uchiyama, Tsuneo; Martinez, Juan J.

2009-01-01

318

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...

319

Polyamine metabolism in an obligately alkalophilic Bacillus alcalophilus that grows at pH 11.0.  

PubMed

Bacillus alcalophilus, an obligately alkalophilic bacterium that grows at pH 11.0, has an intracellular pH of 9.5 or less. Unlike all other living organisms, polyamines (putrescine, spermidine and spermine) in B. alcalophilus, if present, will be largely unprotonated. HPLC analysis indicated that spermidine is the major polyamine in B. alcalophilus, accounting for more than 90% of total polyamines, and the level of spermidine varies during growth. Ornithine decarboxylase activity was not detectable in B. alcalophilus under all conditions examined. When [3H]arginine was added to the culture medium, the radioactivity can be recovered from polyamine pool; the distribution is 3% for putrescine, 94% for spermidine, and 3% for spermine, suggesting the presence of arginine pathway for polyamine biosynthesis. The polyamine transport system in B. alcalphilus appears to be Na+-dependent and is highly sensitive to the inhibition of gramicidin S and valinomycin. PMID:2447890

Chen, K Y; Cheng, S

1988-01-15

320

Intracellular Adaptation of Brucella abortus  

PubMed Central

Macrophages were infected with virulent B. abortus strain 2308 or attenuated strain 19. Intracellular bacteria were recovered at different times after infection and their proteomes compared. The virulent strain initially reduced most biosynthesis and altered its respiration, adaptations reversed later in infection. The attenuated strain was unable to match the magnitude of the virulent strain’s adjustments. The results provide insight into mechanisms utilized by Brucella to establish intracellular infections.

Lamontagne, Julie; Forest, Anik; Marazzo, Elena; Denis, Francois; Butler, Heather; Michaud, Jean-Francois; Boucher, Lyne; Pedro, Ida; Villeneuve, Annie; Sitnikov, Dmitri; Trudel, Karine; Nassif, Najib; Boudjelti, Djamila; Tomaki, Fadi; Chaves-Olarte, Esteban; Guzman-Verri, Caterina; Brunet, Sylvain; Cote-Martin, Alexandra; Hunter, Joanna; Moreno, Edgardo; Paramithiotis, Eustache

2009-01-01

321

Bacterial Rheotaxis  

NASA Astrophysics Data System (ADS)

Rheotaxis is the directed movement of an organism resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates and spermatozoa. Here we show that rheotaxis also occurs in bacteria. Using controlled microfluidic shear flows, we demonstrate and quantify rheotaxis in Bacillus subtilis. A mathematical model of a bacterium swimming in a shear flow is in good agreement with observations and reveals that bacterial rheotaxis results from a subtle interplay between velocity gradients and the helical shape of flagella, which together generate a torque that reorients the cell, altering its swimming direction. The magnitude of the observed rheotactic velocity is comparable to typical chemotactic velocities, suggesting that rheotaxis can interfere with bacterial processes based on directed motility, such as foraging and infection.

Marcos, Marcos; Fu, Henry; Powers, Thomas; Stocker, Roman

2011-11-01

322

The Obligate Mutualist Wigglesworthia glossinidia Influences Reproduction, Digestion, and Immunity Processes of Its Host, the Tsetse Fly?  

PubMed Central

Tsetse flies (Diptera: Glossinidae) are vectors for trypanosome parasites, the agents of the deadly sleeping sickness disease in Africa. Tsetse also harbor two maternally transmitted enteric mutualist endosymbionts: the primary intracellular obligate Wigglesworthia glossinidia and the secondary commensal Sodalis glossinidius. Both endosymbionts are transmitted to the intrauterine progeny through the milk gland secretions of the viviparous female. We administered various antibiotics either continuously by per os supplementation of the host blood meal diet or discretely by hemocoelic injections into fertile females in an effort to selectively eliminate the symbionts to study their individual functions. A symbiont-specific PCR amplification assay and fluorescence in situ hybridization analysis were used to evaluate symbiont infection outcomes. Tetracycline and rifampin treatments eliminated all tsetse symbionts but reduced the fecundity of the treated females. Ampicillin treatments did not affect the intracellular Wigglesworthia localized in the bacteriome organ and retained female fecundity. The resulting progeny of ampicillin-treated females, however, lacked Wigglesworthia but still harbored the commensal Sodalis. Our results confirm the presence of two physiologically distinct Wigglesworthia populations: the bacteriome-localized Wigglesworthia involved with nutritional symbiosis and free-living Wigglesworthia in the milk gland organ responsible for maternal transmission to the progeny. We evaluated the reproductive fitness, longevity, digestion, and vectorial competence of flies that were devoid of Wigglesworthia. The absence of Wigglesworthia completely abolished the fertility of females but not that of males. Both the male and female Wigglesworthia-free adult progeny displayed longevity costs and were significantly compromised in their blood meal digestion ability. Finally, while the vectorial competence of the young newly hatched adults without Wigglesworthia was comparable to that of their wild-type counterparts, older flies displayed higher susceptibility to trypanosome infections, indicating a role for the mutualistic symbiosis in host immunobiology. The ability to rear adult tsetse that lack the obligate Wigglesworthia endosymbionts will now enable functional investigations into this ancient symbiosis.

Pais, Roshan; Lohs, Claudia; Wu, Yineng; Wang, Jingwen; Aksoy, Serap

2008-01-01

323

Francisella tularensis harvests nutrients derived via ATG5-independent autophagy to support intracellular growth.  

PubMed

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

Steele, Shaun; Brunton, Jason; Ziehr, Benjamin; Taft-Benz, Sharon; Moorman, Nathaniel; Kawula, Thomas

2013-08-15

324

Autophagy and bacterial infectious diseases.  

PubMed

Autophagy is a housekeeping process that maintains cellular homeostasis through recycling of nutrients and degradation of damaged or aged cytoplasmic constituents. Over the past several years, accumulating evidence has suggested that autophagy can function as an intracellular innate defense pathway in response to infection with a variety of bacteria and viruses. Autophagy plays a role as a specialized immunologic effector and regulates innate immunity to exert antimicrobial defense mechanisms. Numerous bacterial pathogens have developed the ability to invade host cells or to subvert host autophagy to establish a persistent infection. In this review, we have summarized the recent advances in our understanding of the interaction between antibacterial autophagy (xenophagy) and different bacterial pathogens. PMID:22257885

Yuk, Jae Min; Yoshimori, Tamotsu; Jo, Eun Kyeong

2012-02-29

325

Depression, SSRIs, and the supposed obligation to suffer mentally.  

PubMed

Within both popular and academic literature, concerns have been expressed about the implications of antidepressant use on character development. In this paper, I identify specific versions of these worries and argue that they are misguided. I begin by arguing that the obligation to suffer if it will bring about a noble character is imagined. Legitimate concerns about character enhancement remain, but they do not count against most antidepressant use. Thus there is no moral prohibition against antidepressant use. Furthermore, some of the calls for caution about antidepressant use, such as those expressed by the President's Council on Bioethics, are overstated. PMID:17091563

Olsen, J Mark

2006-09-01

326

A RAPID METHOD FOR DETECTION AND QUANTIFICATION OF BACTERIAL DNA IN RUST FUNGAL DNA SAMPLES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rust fungi are obligate parasitic plant pathogens and molecular analysis often depends on extraction of DNA from asexual urediniospores collected from plant tissue. Bacterial DNA contamination of the rust fungal DNA can be a significant problem. A quantitative real-time polymerase chain reaction (Q-...

327

Desulfurispira natronophila gen. nov. sp. nov.: an obligately anaerobic dissimilatory sulfur-reducing bacterium from soda lakes.  

PubMed

Anaerobic enrichment cultures with elemental sulfur as electron acceptor and either acetate or propionate as electron donor and carbon source at pH 10 and moderate salinity inoculated with sediments from soda lakes in Kulunda Steppe (Altai, Russia) resulted in the isolation of two novel members of the bacterial phylum Chrysiogenetes. The isolates, AHT11 and AHT19, represent the first specialized obligate anaerobic dissimilatory sulfur respirers from soda lakes. They use either elemental sulfur/polysulfide or arsenate as electron acceptor and a few simple organic compounds as electron donor and carbon source. Elemental sulfur is reduced to sulfide through intermediate polysulfide, while arsenate is reduced to arsenite. The bacteria belong to the obligate haloalkaliphiles, with a pH growth optimum from 10 to 10.2 and a salt range from 0.2 to 3.0 M Na(+) (optimum 0.4-0.6 M). According to the phylogenetic analysis, the two strains were close to each other, but distinct from the nearest relative, the haloalkaliphilic sulfur-reducing bacterium Desulfurispirillum alkaliphilum, which was isolated from a bioreactor. On the basis of distinct phenotype and phylogeny, the soda lake isolates are proposed as a new genus and species, Desulfurispira natronophila (type strain AHT11(T) = DSM22071(T) = UNIQEM U758(T)). PMID:20407798

Sorokin, D Y; Muyzer, G

2010-04-21

328

Bacterial Growth  

NSDL National Science Digital Library

Dr. Brett Finlay shows how bacteria can grow rapidly to incredible numbers, and also explains what limits this explosive growth. This resource would be great preparation material for a classroom discussion or video presentation for both the students and the teacher. This visual helps further broaden the knowledge of students in both the upper high school and college undergraduate on bacterial growth. The lecture is featured on the DVD 2000 and Beyond: Confronting the Microbe Menace, available free from HHMI. The video is 54 seconds long and available on WMV (10MB) and MOV (8MB). All Infection Disease videos can be found at http://www.hhmi.org/biointeractive/disease/video.html .

Howard Hughes Medical Institute (;)

2007-03-27

329

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.

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

2011-01-01

330

Fusion of Chlamydia trachomatis-Containing Inclusions Is Inhibited at Low Temperatures and Requires Bacterial Protein Synthesis  

Microsoft Academic Search

The human pathogen Chlamydia trachomatis is an obligate intracellular bacterium with a unique develop- mental cycle. Within the host cell cytoplasm, it resides within a membrane-bound compartment, the inclusion. A distinguishing characteristic of the C. trachomatis life cycle is the fusion of the chlamydia-containing inclusions with each other in the host cell cytoplasm. We report that fusion of inclusions does

CHRISTIAAN VAN OOIJ; ELLEN HOMOLA; ELEANOR KINCAID; JOANNE ENGEL

1998-01-01

331

Facultative and obligate slavery in formicine ants: frequency of slavery, and proportion and size of slaves  

Microsoft Academic Search

Slave-making ants raid nests of other ant species, capture the developing offspring and rear them to slave workers. Here we compare slave-making of three formicine slave-making ants: the facultativeFormica subnuda, the obligatePolyergus breviceps, andF. subintegrawhich previously has been considered facultative but appears to be an obligate slave-making ant. IfF. subintegrais an obligate slavemaker, slave-making ofF. subintegrashould differ from that ofF.

RIITTA SAVOLAINEN; RICHARD J. DESLIPPE

1996-01-01

332

Female-biased obligate strategies in a partially migratory population.  

PubMed

Partial migration occurs when a breeding population consists of seasonal migrants and year-round residents. Although it is common among birds, the basis of individual movement decisions within partially migratory populations is still unresolved. Over 4 years, we used state of the art tracking techniques, a combination of geolocators and radio transmitters, to follow individual European blackbirds Turdus merula year round from a partially migratory population to determine individual strategies and departure and arrival dates. The individual-based tracking combined with measures of energetic and hormonal (corticosterone) state enabled us to distinguish between obligate and facultative migration and to test several classical hypotheses of partial migration: the 'Arrival Time'-, 'Dominance'- and 'Thermal Tolerance'-hypotheses. Two distinct periods of departures from the breeding grounds were observed during the study; one in early autumn, and another during the midst of winter. Although blackbirds that migrated in autumn were never observed overwintering within 300 km of the study site, four individuals that departed in the winter were observed within 40 km. Females were significantly more likely to migrate in autumn than males but there was no difference in the age or body size of migrants and non migrants in autumn. Just prior to autumn migration, migrants had higher fat scores than non migrants and tended to have higher concentrations of baseline corticosterone, but similar concentrations of triglycerides. Unlike autumn migrants, we found no difference between the tendencies of males versus females to depart in winter, nor did we find any difference in body size or age of individuals that departed in the winter. Autumn migration was sex biased and resembled obligate migration. Our results provide strong support for the 'Arrival Time' hypothesis for partial migration in the autumn. We found no clear support for the 'Dominance' or 'Thermal Tolerance' hypotheses. By tracking individuals year round, we were able to identify a second period of departures. Overall, these results suggest the co-occurrence of obligate autumn migrants, winter movements and sedentary individuals within a single population. PMID:23363245

Fudickar, Adam M; Schmidt, Andreas; Hau, Michaela; Quetting, Michael; Partecke, Jesko

2013-01-31

333

Mycobacterium intracellulare Reference Precipitation System  

Microsoft Academic Search

Characteristics of a Mycobacterium intracellulare reference precipitation system for immunodiffusion and immunoelectrophoresis analyses are presented. The system was produced by the initiative of the International Working Group on Mycobacterial Taxonomy, and the purpose is to permit comparisons of precipitinogenic patterns of mycobacteria obtained in different laboratories. The reference material, consisting of an antigen preparation and a corresponding antiserum, is available

MALIN RIDELL; SOTIROS D. CHAPARAS; PHILIPPE DESMETTRE; ARNE LIND; ORJAN OUCHTERLONY; MARIE-FRANCOISE THOREL; LAWRENCE G. WAYNE

334

Mechanisms of intracellular protein transport  

Microsoft Academic Search

Recent advances have uncovered the general protein apparatus used by all eukaryotes for intracellular transport, including secretion and endocytosis, and for triggered exocytosis of hormones and neurotransmitters. Membranes are shaped into vesicles by cytoplasmic coats which then dissociate upon GTP hydrolysis. Both vesicles and their acceptor membranes carry targeting proteins which interact specifically to initiate docking. A general apparatus then

James E. Rothman

1994-01-01

335

Intracellular and extracellular PGPR: commonalities and distinctions in the plant–bacterium signaling processes  

Microsoft Academic Search

Plant growth promoting bacteria (PGPR) associations range in degree of bacterial proximity to the root and intimacy of association. In general, these can be separated into extracellular PGPR (ePGPR), existing in the rhizosphere, on the rhizoplane or in the spaces between cells of the root cortex, and intracellular PGPR (iPGPR), which exist inside root cells, generally in specialized nodular structures.

E. J. Gray; D. L. Smith

2005-01-01

336

Vaccine requirements for sustained cellular immunity to an intracellular parasitic infection  

Microsoft Academic Search

The humoral immunity induced by many viral and bacterial vaccines mediates protection that is maintained over a long period of time. In contrast, for other intracellular infections (such as with Leishmania major or Mycobacterium tuberculosis) for which cell-mediated immunity is required for protection, the mechanisms for developing durable responses after vaccination have not been well defined. Here we demonstrate that

Sanjay Gurunathan; Calman Prussin; David L. Sacks; Robert A. Seder

1998-01-01

337

The Establishment of Intracellular Symbiosis in an Ancestor of Cockroaches and Termites  

Microsoft Academic Search

All cockroaches examined so far have been found to harbour a bacterial endosymbiont in specialized cells of the fat body, whereas Mastotermes darwiniensis is the only termite currently known to harbour an intracellular symbiont. The localization and mode of transmission of these bacteria are surprisingly similar, but so far no data have been published on their phylogenetic relationships. To address

Claudio Bandi; Massimo Sironi; Giuseppe Damiani; Lorenzo Magrassi; Christine A. Nalepa; Ugo Laudani; Luciano Sacchi

1995-01-01

338

T-Cell-Independent Humoral Immunity Is Sufficient for Protection against Fatal Intracellular Ehrlichia Infection  

Microsoft Academic Search

Although humoral immunity has been shown to contribute to host defense during intracellular bacterial infections, its role has generally been ancillary. Instead, CD4 T cells are often considered to play the dominant role in protective immunity via their production of type I cytokines. Our studies of highly pathogenic Ehrlichia bacteria isolated from Ixodes ovatus (IOE) reveal, however, that this paradigm

Constantine Bitsaktsis; Bisweswar Nandi; Rachael Racine; Katherine C. MacNamara; Gary Winslow

2007-01-01

339

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

340

Obligate versus rich patch opportunism: evolution and endocrine mechanisms.  

PubMed

Opportunistic breeding has been hypothesized to evolve in response to rare or unpredictable resource pulses. In this traditional view of opportunism, individuals invest heavily in reproduction whenever conditions are permissive for breeding, perhaps at the expense of investment in survival. We term this strategy 'obligate opportunism' (OBO). We also present an additional strategy that could account for the evolution of opportunism. High mobility may allow individuals to move between rich patches of resources that are spatially or temporally unpredictable, reducing exposure to food scarcity and taking advantage of breeding opportunities. This strategy, which we term 'rich patch exploiter' (RPE), predicts that investment in survival-enhancing processes may occur at the expense of reproduction despite high resource availability. We review examples to determine which opportunists better match predictions from the OBO strategy or the RPE strategy and then review endocrine profiles in the context of the two strategies. PMID:23612018

Cornelius, J M; Watts, H E; Dingle, H; Hahn, T P

2013-04-20

341

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.

Espindola, Anahi; Alvarez, Nadir

2011-01-01

342

Acquisition of nutrients by Chlamydiae: unique challenges of living in an intracellular compartment  

PubMed Central

Summary The Chlamydiae are obligate intracellular pathogen that replicate within a membrane-bound vacuole, termed the “inclusion”. From this compartment, bacteria acquire essential nutrients by selectively redirecting transport vesicles and hijacking intracellular organelles. Re-routing is achieved by several mechanisms including proteolysis-mediated fragmentation of the Golgi apparatus, recruitment of Rab GTPases and SNAREs, and translocation of cytoplasmic organelles into the inclusion lumen. Given Chlamydiae’s extended co-evolution with eukaryotic cells, it is likely that co-option of multiple cellular pathways is a strategy to provide redundancy in the acquisition of essential nutrients from the host and has contributed to the success of these highly adapted pathogens.

Saka, Hector Alex; Valdivia, Raphael H.

2011-01-01

343

QS-type bacterial signal molecules of nonpeptide origin  

Microsoft Academic Search

This review classifies and analyzes the literature data on bacterial autoinducers (AI), the signal molecules produced and\\u000a secreted by bacterial cells and responsible for intercellular communication (quorum sensing, QS). The most important families\\u000a of nonpeptide AI are discussed, including N-acyl homoserine lactones, derivatives of 2-methyl-2,3,4,5-tetrahydroxy tetrahydrofuran, indole and quinoline derivatives,\\u000a and adrenalinerelated compounds. The data is provided on the intracellular

A. O. Shpakov

2009-01-01

344

Cytochemical Differences in Bacterial Glycocalyx  

NASA Astrophysics Data System (ADS)

To examine new cytochemical aspects of the bacterial adhesion, a strain 41452/01 of the oral commensal Streptococcus sanguis and a wild strain of Staphylococcus aureus were grown with and without sucrose supplementation for 6 days. Osmiumtetraoxyde (OsO4), uranyl acetate (UA), ruthenium red (RR), cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs), and the tannic acid-metal salt technique (TAMST) were applied for electron microscopy. Cytochemically, only RR-positive fimbriae in S. sanguis were visualized. By contrast, some types of fimbriae staining were observed in S. aureus glycocalyx: RR-positive, OsO4-positive, tannophilic and CB-positive with ceasing point at 0.3 M MgCl2. The CB staining with CEC, used for the first time for visualization of glycoproteins of bacterial glycocalyx, also reveals intacellular CB-positive substances-probably the monomeric molecules, that is, subunits forming the fimbriae via extracellular assembly. Thus, glycosylated components of the biofilm matrix can be reliably related to single cells. The visualization of intracellular components by CB with CEC enables clear distinction between S. aureus and other bacteria, which do not produce CB-positive substances. The small quantities of tannophilic substances found in S. aureus makes the use of TAMST for the same purpose difficult. The present work protocol enables, for the first time, a partial cytochemical differentiation of the bacterial glycocalyx.

Krautgartner, Wolf Dietrich; Vitkov, Ljubomir; Hannig, Matthias; Pelz, Klaus; Stoiber, Walter

2005-02-01

345

Attitudes Toward Family Obligation Among Adolescents in Contemporary Urban and Rural China  

ERIC Educational Resources Information Center

|A sense of obligation to support, assist, and respect the family was examined among approximately 700 urban and rural 10th- (M=16.6 years) and 12th- (M=18.9 years) grade students in the People's Republic of China. Urban male adolescents reported a weaker sense of family obligation than did rural male adolescents and both urban and rural female…

Fuligni, Andrew J.; Zhang, Wenxin

2004-01-01

346

47 CFR 51.603 - Resale obligation of all local exchange carriers.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Resale obligation of all local exchange carriers. 51.603 Section... § 51.603 Resale obligation of all local exchange carriers. (a) A LEC shall...terms and conditions that are reasonable and non-discriminatory. (b) A LEC...

2011-10-01

347

Allocating and Funding Universal Service Obligations in a Competitive Network Market  

Microsoft Academic Search

We examine, in a network market open to competition, various mechanisms of allocating and funding ''universal service obligations'' among agents (rival operators and consumers). The obligations we consider are geographic ubiquity and non discrimination. We analyze, from both the efficiency and equity point of views, the respective advantages of a ''restricted-entry'' system (where the entrant is not allowed to serve

Philippe Choné; Laurent Flochel; Anne Perrot

1999-01-01

348

76 FR 63561 - Reexamination of Roaming Obligations of Commercial Mobile Radio Service Providers and Other...  

Federal Register 2010, 2011, 2012, 2013

...Roaming Obligations of Commercial Mobile Radio Service Providers and Other Providers...Commission, at (202) 418-0214 or via the Internet at Judith-B.Herman@fcc.gov. SUPPLEMENTARY...Roaming Obligations of Commercial Mobile Radio Service Providers and Other...

2011-10-13

349

Newcomer Psychological Contracts and Employee Socialization Activities: Does Perceived Balance in Obligations Matter?  

ERIC Educational Resources Information Center

We sought to determine the extent to which one's beliefs about the relationship between an employee and an organization at the start of employment influence subsequent socialization activities. The balance of employee exchange relationships, employee perceptions of both their own obligations and the employers' obligations, were collected from 120…

Payne, Stephanie C.; Culbertson, Satoris S.; Boswell, Wendy R.; Barger, Eric J.

2008-01-01

350

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

ERIC Educational Resources Information Center

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

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

2012-01-01

351

Pebbles in a Pond: Learner, Teacher, and Policy Perspectives on Mutual Obligation.  

ERIC Educational Resources Information Center

|This book contains nine chapters, by various authors, containing research and policy perspectives on issues of mutual obligation between teachers and students, especially in Australia. The following are included: (1) "Researching Literacy, Language, and Numeracy and Mutual Obligation: An Introduction to Some Issues" (Sheilagh Kelly and Liz…

Adult Literacy and Numeracy Australian Research Consortium, Melbourne (Victoria). Victorian Centre.

352

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

ERIC Educational Resources Information Center

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

van Geel, Mitch; Vedder, Paul

2011-01-01

353

28 CFR 811.4 - Determination of the obligation to register and the length of registration.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Determination of the obligation...DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.4 Determination of the obligation...that a person is a sex offender and that...CSOSA makes those determinations. CSOSA also...

2009-07-01

354

28 CFR 811.4 - Determination of the obligation to register and the length of registration.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Determination of the obligation...DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.4 Determination of the obligation...that a person is a sex offender and that...CSOSA makes those determinations. CSOSA also...

2013-07-01

355

28 CFR 811.4 - Determination of the obligation to register and the length of registration.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Determination of the obligation...DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.4 Determination of the obligation...that a person is a sex offender and that...CSOSA makes those determinations. CSOSA also...

2010-07-01

356

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

Code of Federal Regulations, 2013 CFR

...for obligations transmitted at death, but contains no requirement...transmitted, the date of his death, and the internal revenue district...the election is made under the penalties of perjury. (2) Filing...obligation was transmitted at A's death to B who filed a...

2013-04-01

357

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

ERIC Educational Resources Information Center

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

van Geel, Mitch; Vedder, Paul

2011-01-01

358

42 CFR 137.309 - How are NEPA and NHPA obligations typically enforced?  

Code of Federal Regulations, 2011 CFR

NEPA and NHPA obligations are typically enforced by interested parties who may file lawsuits against Federal agencies alleging that the agencies have not complied with their legal obligations under NEPA and NHPA. These lawsuits may only be filed in Federal court under the provisions of the APA, 5...

2011-10-01

359

The obligately lichenicolous genus Lichenoconium represents a novel lineage in the Dothideomycetes  

Microsoft Academic Search

Lichenicolous fungi are obligately lichen-associated organisms that have evolved many times throughout the Ascomycota and Basidiomycota. Approximately 20% of lichenicolous ascomycetes are recognized only from asexual (anamorphic) characteristics, so the phylogenetic position of many groups has never been resolved. Here we present the first molecular phylogeny of Lichenoconium, a genus of strictly asexual, obligately lichenicolous species with broad geographic distributions

James D. Lawrey; Paul Diederich; Matthew P. Nelsen; Masoumeh Sikaroodi; Patrick M. Gillevet; A. Maarten Brand; Pieter van den Boom

2011-01-01

360

26 CFR 1.1037-1 - Certain exchanges of United States obligations.  

Code of Federal Regulations, 2010 CFR

...States of obligations of the United States issued under the Second Liberty Bond Act (31...exchange obligations of the United States issued under the Second Liberty Bond Act for other...registered in the name of C, who is B's son. Each $5,000...

2010-04-01

361

26 CFR 1.1037-1 - Certain exchanges of United States obligations.  

Code of Federal Regulations, 2010 CFR

...States of obligations of the United States issued under the Second Liberty Bond Act (31...exchange obligations of the United States issued under the Second Liberty Bond Act for other...registered in the name of C, who is B's son. Each $5,000...

2009-04-01

362

77 FR 50544 - Notice of Release From Federal Surplus Property and Grant Assurance Obligations at Porterville...  

Federal Register 2010, 2011, 2012, 2013

...Administration Notice of Release From Federal Surplus Property and Grant Assurance Obligations...California from all conditions contained in the Surplus Property Deed and Grant Assurances because...imposed on a federally obligated airport by surplus property conveyance deeds or grant...

2012-08-21

363

76 FR 49477 - Termination of Federal Home Loan Bank Resolution Funding Corporation Obligation  

Federal Register 2010, 2011, 2012, 2013

...satisfied their statutory obligation to contribute a percentage of their annual net earnings...enacted, the law required the Banks to contribute $300 million annually toward the RefCorp...Banks would satisfy their obligation to contribute to the RefCorp debt service...

2011-08-10

364

Goods with embedded software: Obligations under Section 12 of the Sale of Goods Act 1979  

Microsoft Academic Search

The Sale of Goods Act 1979, section 12 imposes obligations on sellers. Sellers must have the right to sell the goods, and they impliedly warranty that the buyer will enjoy quiet possession. Actions by intellectual property rights holders can lead to liability for sellers for breach of the section 12 obligations. Recent technological change has brought about the development of

Sean Thomas

2012-01-01

365

Energy Saving Obligations and White Certificates: Ideas and Considerations for the Transport Sector  

Microsoft Academic Search

A lot of policy interest and analysis has been focused on energy saving obligations on energy distributors or suppliers (mainly electricity and gas) coupled with trading of certified energy savings via tradable white certificates. While in the European Union the Energy Services Directive (2006\\/32\\/EC) also applies to transport fuels and some of the existing energy saving obligations allow certification of

Paolo Bertoldi; Silvia Rezessy; Jillian Anable; Patrick Jochem; Vlasis Oikonomou

2011-01-01

366

26 CFR 1.453-11 - Installment obligations received from a liquidating corporation.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Installment obligations received from a liquidating...Gross Income Included § 1.453-11 Installment obligations received from a liquidating...section 453(h)(1)(C) (relating to installment sales of depreciable property...

2010-04-01

367

26 CFR 1.453-11 - Installment obligations received from a liquidating corporation.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Installment obligations received from a liquidating...Gross Income Included § 1.453-11 Installment obligations received from a liquidating...section 453(h)(1)(C) (relating to installment sales of depreciable property...

2009-04-01

368

11 CFR 104.11 - Continuous reporting of debts and obligations.  

Code of Federal Regulations, 2010 CFR

...date on which the debt or obligation is incurred, except that any obligation incurred for rent, salary or other regularly reoccurring administrative expense shall not be reported as a debt before the payment due date. See 11 CFR 116.6. If the...

2009-01-01

369

11 CFR 104.11 - Continuous reporting of debts and obligations.  

Code of Federal Regulations, 2010 CFR

...date on which the debt or obligation is incurred, except that any obligation incurred for rent, salary or other regularly reoccurring administrative expense shall not be reported as a debt before the payment due date. See 11 CFR 116.6. If the...

2010-01-01

370

Bacterial Communities of Two Parthenogenetic Aphid Species Cocolonizing Two Host Plants across the Hawaiian Islands ?  

PubMed Central

Aphids (Hemiptera: Aphididae) have been the focus of several studies with respect to their interactions with inherited symbionts, but bacterial communities of most aphid species are still poorly characterized. In this research, we used bar-coded pyrosequencing to characterize bacterial communities in aphids. Specifically, we examined the diversity of bacteria in two obligately parthenogenetic aphid species (the melon aphid, Aphis gossypii, and the cardamom aphid, Pentalonia caladii) cocolonizing two plant species (taro, Colocasia esculenta, and ginger, Alpinia purpurata) across four Hawaiian Islands (Hawaii, Kauai, Maui, and Oahu). Results from this study revealed that heritable symbionts dominated the bacterial communities for both aphid species. The bacterial communities differed significantly between the two species, and A. gossypii harbored a more diverse bacterial community than P. caladii. The bacterial communities also differed across aphid populations sampled from the different islands; however, communities did not differ between aphids collected from the two host plants.

Jones, Ryan T.; Bressan, Alberto; Greenwell, April M.; Fierer, Noah

2011-01-01

371

Intracellular magnesium and magnesium buffering  

Microsoft Academic Search

The development of new techniques for measuring intracellular free Mg2+ during the 1980s has provided investigators with the tools needed to produce new insights into the regulation of cellular magnesium. Within the limits of this technology, it appears that all mammalian cells maintain free cytosolic Mg2+ levels within the fairly narrow range of 0.25–1 mM. While transport mechanisms and sequestration within

Robert D. Grubbs

2002-01-01

372

Mechanisms of intracellular protein transport  

NASA Astrophysics Data System (ADS)

Recent advances have uncovered the general protein apparatus used by all eukaryotes for intracellular transport, including secretion and endocytosis, and for triggered exocytosis of hormones and neurotransmitters. Membranes are shaped into vesicles by cytoplasmic coats which then dissociate upon GTP hydrolysis. Both vesicles and their acceptor membranes carry targeting proteins which interact specifically to initiate docking. A general apparatus then assembles at the docking site and fuses the vesicle with its target.

Rothman, James E.

1994-11-01

373

Stochastic models of intracellular transport  

NASA Astrophysics Data System (ADS)

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

Bressloff, Paul C.; Newby, Jay M.

2013-01-01

374

Citizens' obligation to obey the law: an empirical study of Guangzhou, China.  

PubMed

For thousands of years, China primarily used morality for its social control. Since its economic reform starting in 1978, China has moved toward legal control. Two fundamental questions, however, remain understudied in China: (a) the degree to which citizens feel obligated to obey the law and (b) the sources of citizens' perceived obligation to obey the law. This study was intended to answer these questions based on random surveys of 1,196 residents from Guangzhou, China. The study revealed that the vast majority of citizens in Guangzhou felt obligated to obey the law irrespective of their personal feelings. Normative and instrumental perspectives were important sources of Guangzhou citizens' perceived obligation to obey the law. In addition, Guangzhou citizens' perception of obligation to obey the law was related to not only individual-level variables but also neighborhood contextual factors. PMID:22222495

Jiang, Shanhe; Wu, Yuning; Wang, Jin

2012-01-05

375

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

2012-03-16

376

Bacterial concrete  

NASA Astrophysics Data System (ADS)

Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self-repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii and Sporosarcina bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and CaCl2 medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places. Energy- dispersive X-ray (EDX) spectra of the microbial precipitation on the surface of the crack indicated the abundance of calcium and the precipitation was inferred to be calcite (CaCO3).

Ramakrishnan, Venkataswamy; Ramesh, K. P.; Bang, S. S.

2001-04-01

377

Bacterial tyrosinases.  

PubMed

Tyrosinases are nearly ubiquitously distributed in all domains of life. They are essential for pigmentation and are important factors in wound healing and primary immune response. Their active site is characterized by a pair of antiferromagnetically coupled copper ions, CuA and CuB, which are coordinated by six histidine residues. Such a "type 3 copper centre" is the common feature of tyrosinases, catecholoxidases and haemocycanins. It is also one of several other copper types found in the multi-copper oxidases (ascorbate oxidase, laccase). The copper pair of tyrosinases binds one molecule of atmospheric oxygen to catalyse two different kinds of enzymatic reactions: (1) the ortho-hydroxylation of monophenols (cresolase activity) and (2) the oxidation of o-diphenols to o-diquinones (catecholase activity). The best-known function is the formation of melanins from L-tyrosine via L-dihydroxyphenylalanine (L-dopa). The complicated hydroxylation mechanism at the active centre is still not completely understood, because nothing is known about their tertiary structure. One main reason for this deficit is that hitherto tyrosinases from eukaryotic sources could not be isolated in sufficient quantities and purities for detailed structural studies. This is not the case for prokaryotic tyrosinases from different Streptomyces species, having been intensively characterized genetically and spectroscopically for decades. The Streptomyces tyrosinases are non-modified monomeric proteins with a low molecular mass of ca. 30kDa. They are secreted to the surrounding medium, where they are involved in extracellular melanin production. In the species Streptomyces, the tyrosinase gene is part of the melC operon. Next to the tyrosinase gene (melC2), this operon contains an additional ORF called melC1, which is essential for the correct expression of the enzyme. This review summarizes the present knowledge of bacterial tyrosinases, which are promising models in order to get more insights in structure, enzymatic reactions and functions of "type 3 copper" proteins in general. PMID:16423650

Claus, Harald; Decker, Heinz

2005-09-06

378

Molecular characterization and localization of the obligate endosymbiotic bacterium in the birch catkin bug Kleidocerys resedae (Heteroptera: Lygaeidae, Ischnorhynchinae).  

PubMed

In contrast to specific bacterial symbionts of many stinkbugs, which are harboured extracellularly in the lumina of midgut sacs or tubular outgrowths, the obligate endosymbiont of birch catkin bug Kleidocerys resedae (Heteroptera: Lygaeidae) resides in a red-coloured, raspberry-shaped mycetome, localized abdominally, close to the midgut section. Phylogenetic analysis, based on the 16S rRNA gene and the groEL (chaperonin) gene, showed that the bacteria belong to the gamma-subdivision of the Proteobacteria and revealed a phylogenetic relationship with bacterial endosymbionts of Wigglesworthia glossinidia, the primary symbiont of tse-tse fly Glossina brevipalpis. Furthermore, RFLP analysis and sequencing revealed that K. resedae was also infected by Alphaproteobacteria of the genera Wolbachia and Rickettsia. The distribution and transmission of Kleidocerys endosymbiont in adults and all nymph stages were studied using FISH. The detection of symbionts at the anterior poles of developing eggs indicated that endosymbionts are transmitted vertically to offspring. Ultrastructural examinations by electron microscopy revealed the packed accommodation of rod-shaped bacteria in the cytoplasm of mycetocytes. A new genus and species name, 'Candidatus Kleidoceria schneideri', is proposed for this newly characterized clade of symbiotic bacteria. PMID:20500529

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

2010-04-19

379

Intracellular parasitism of macrophages by Cryptococcus neoformans  

Microsoft Academic Search

Cryptococcus neoformans, an encapsulated fungal pathogen, causes meningoencephalitis in immunocompromised patients. Recent in vivo studies have demonstrated that C. neoformans is a facultative intracellular pathogen, as was previously suggested by in vitro studies. For survival in macrophages, C. neoformans utilizes a novel strategy for intracellular parasitism that includes the accumulation of intracellular polysaccharide in cytoplasmic vesicles. Confirmation of the fact

Marta Feldmesser; Stephanie Tucker; Arturo Casadevall

2001-01-01

380

Bacterial start site prediction  

Microsoft Academic Search

With the growing number of completely sequenced bacterial genes, accurate gene prediction in bacterial genomes remains an important problem. Although the existing tools predict genes in bacterial genomes with high overall accuracy, their ability to pinpoint the translation start site remains unsatisfactory. In this paper, we present a novel approach to bacterial start site prediction that takes into account multiple

Sridhar S. Hannenhalli; William S. Hayes; Artemis G. Hatzigeorgiou; James W. Fickett

1999-01-01

381

Mechanisms of Obligatory Intracellular Infection with Anaplasma phagocytophilum  

PubMed Central

Summary: Anaplasma phagocytophilum persists in nature by cycling between mammals and ticks. Human infection by the bite of an infected tick leads to a potentially fatal emerging disease called human granulocytic anaplasmosis. A. phagocytophilum is an obligatory intracellular bacterium that replicates inside mammalian granulocytes and the salivary gland and midgut cells of ticks. A. phagocytophilum evolved the remarkable ability to hijack the regulatory system of host cells. A. phagocytophilum alters vesicular traffic to create an intracellular membrane-bound compartment that allows replication in seclusion from lysosomes. The bacterium downregulates or actively inhibits a number of innate immune responses of mammalian host cells, and it upregulates cellular cholesterol uptake to acquire cholesterol for survival. It also upregulates several genes critical for the infection of ticks, and it prolongs tick survival at freezing temperatures. Several host factors that exacerbate infection have been identified, including interleukin-8 (IL-8) and cholesterol. Host factors that overcome infection include IL-12 and gamma interferon (IFN-?). Two bacterial type IV secretion effectors and several bacterial proteins that associate with inclusion membranes have been identified. An understanding of the molecular mechanisms underlying A. phagocytophilum infection will foster the development of creative ideas to prevent or treat this emerging tick-borne disease.

Rikihisa, Yasuko

2011-01-01

382

Intracellular Bacteria Encode Inhibitory SNARE-Like Proteins  

PubMed Central

Pathogens use diverse molecular machines to penetrate host cells and manipulate intracellular vesicular trafficking. Viruses employ glycoproteins, functionally and structurally similar to the SNARE proteins, to induce eukaryotic membrane fusion. Intracellular pathogens, on the other hand, need to block fusion of their infectious phagosomes with various endocytic compartments to escape from the degradative pathway. The molecular details concerning the mechanisms underlying this process are lacking. Using both an in vitro liposome fusion assay and a cellular assay, we showed that SNARE-like bacterial proteins block membrane fusion in eukaryotic cells by directly inhibiting SNARE-mediated membrane fusion. More specifically, we showed that IncA and IcmG/DotF, two SNARE-like proteins respectively expressed by Chlamydia and Legionella, inhibit the endocytic SNARE machinery. Furthermore, we identified that the SNARE-like motif present in these bacterial proteins encodes the inhibitory function. This finding suggests that SNARE-like motifs are capable of specifically manipulating membrane fusion in a wide variety of biological environments. Ultimately, this motif may have been selected during evolution because it is an efficient structural motif for modifying eukaryotic membrane fusion and thus contribute to pathogen survival.

Paumet, Fabienne; Wesolowski, Jordan; Garcia-Diaz, Alejandro; Delevoye, Cedric; Aulner, Nathalie; Shuman, Howard A.; Subtil, Agathe; Rothman, James E.

2009-01-01

383

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

384

20 CFR 1002.261 - Who is responsible for funding any plan obligation to provide the employee with pension benefits?  

Code of Federal Regulations, 2013 CFR

...plan obligation to provide the employee with pension benefits? 1002.261 Section 1002.261 Employees' Benefits OFFICE OF THE...VETERANS' EMPLOYMENT AND TRAINING SERVICE, DEPARTMENT OF LABOR...obligation to provide the employee with pension...

2013-04-01

385

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

386

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

387

41 CFR 101-6.2105 - What is the Administrator's obligation with respect to Federal interagency coordination?  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false What is the Administrator's obligation with respect...Property Management Regulations System FEDERAL PROPERTY MANAGEMENT...101-6.2105 What is the Administrator's obligation with respect...interagency coordination? The Administrator, to the extent...

2012-07-01

388

25 CFR 162.239 - How will payment rights and obligations relating to agricultural land be allocated between the...  

Code of Federal Regulations, 2010 CFR

...How will payment rights and obligations relating to agricultural land be allocated between the Indian landowners and the...How will payment rights and obligations relating to agricultural land be allocated between the Indian landowners and...

2010-04-01

389

25 CFR 162.239 - How will payment rights and obligations relating to agricultural land be allocated between the...  

Code of Federal Regulations, 2010 CFR

...How will payment rights and obligations relating to agricultural land be allocated between the Indian landowners and the...How will payment rights and obligations relating to agricultural land be allocated between the Indian landowners and...

2009-04-01

390

26 CFR 1.6049-3 - Statements to recipients of interest payments and holders of obligations to which there is...  

Code of Federal Regulations, 2011 CFR

...obligations to which there is attributed original issue discount in calendar years before 1983...obligations to which there is attributed original issue discount in calendar years before 1983...or 1087-OID with respect to original issue discount includible in gross...

2011-04-01

391

26 CFR 1.6049-3 - Statements to recipients of interest payments and holders of obligations to which there is...  

Code of Federal Regulations, 2013 CFR

...obligations to which there is attributed original issue discount in calendar years before 1983...obligations to which there is attributed original issue discount in calendar years before 1983...or 1087-OID with respect to original issue discount includible in gross...

2013-04-01

392

26 CFR 1.6049-6 - Statements to recipients of interest payments and holders of obligations for attributed original...  

Code of Federal Regulations, 2013 CFR

...holders of obligations for attributed original issue discount. 1.6049-6 Section 1...holders of obligations for attributed original issue discount. (a) Requirement of furnishing...payments of interest (other than original issue discount) to any person during a...

2013-04-01

393

Unprecedented loss of ammonia assimilation capability in a urease-encoding bacterial mutualist  

PubMed Central

Background Blochmannia are obligately intracellular bacterial mutualists of ants of the tribe Camponotini. Blochmannia perform key nutritional functions for the host, including synthesis of several essential amino acids. We used Illumina technology to sequence the genome of Blochmannia associated with Camponotus vafer. Results Although Blochmannia vafer retains many nutritional functions, it is missing glutamine synthetase (glnA), a component of the nitrogen recycling pathway encoded by the previously sequenced B. floridanus and B. pennsylvanicus. With the exception of Ureaplasma, B. vafer is the only sequenced bacterium to date that encodes urease but lacks the ability to assimilate ammonia into glutamine or glutamate. Loss of glnA occurred in a deletion hotspot near the putative replication origin. Overall, compared to the likely gene set of their common ancestor, 31 genes are missing or eroded in B. vafer, compared to 28 in B. floridanus and four in B. pennsylvanicus. Three genes (queA, visC and yggS) show convergent loss or erosion, suggesting relaxed selection for their functions. Eight B. vafer genes contain frameshifts in homopolymeric tracts that may be corrected by transcriptional slippage. Two of these encode DNA replication proteins: dnaX, which we infer is also frameshifted in B. floridanus, and dnaG. Conclusions Comparing the B. vafer genome with B. pennsylvanicus and B. floridanus refines the core genes shared within the mutualist group, thereby clarifying functions required across ant host species. This third genome also allows us to track gene loss and erosion in a phylogenetic context to more fully understand processes of genome reduction.

2010-01-01

394

Realizing benefit sharing - the case of post-study obligations.  

PubMed

In 2006, the Indonesian government decided to withhold avian flu samples from the World Health Organization. They argued that even though Indonesian samples were crucial to the development of vaccines, the results of vaccine research would be unaffordable for its citizens. Commentaries on the case varied from alleging blackmail to welcoming this strong stance against alleged exploitation. What is clear is that the concern expressed is related to benefit sharing. Benefit sharing requires resource users to return benefits to resource providers in order to achieve justice. One benefit sharing tool within health research is the duty to provide a health care intervention which has been proven to be beneficial (or alternative benefits) to research participants after a study has been concluded. This duty is generally known as a post-study obligation. It was enshrined in the Declaration of Helsinki in 2000 and re-emphasized in 2008. Yet, there are few, if any, examples of good practice. In this article, we analyse the obstacles to giving more bite to benefit sharing provisions in health research through ethical review. We conclude that the provision of post-study access to healthcare interventions is not a promising mechanism when monitored through research ethics committees. Alternative benefit provision is preferable if one focuses on achieving compliance. However, even the latter faces challenges, which we address in specific recommendations. PMID:21241344

Schroeder, Doris; Gefenas, Eugenijus

2011-01-17

395

Ethical obligations and counseling challenges in cancer genetics.  

PubMed

Cancer genetics is creating new practice opportunities in medical genetics, oncology, and primary care. The ethical and counseling challenges of this new area of practice are not unique but sometimes take new form in the context of genetic risk. This article uses cases to explore the issues associated with shared family risk, including competing concerns of family members, duty to warn relatives of genetic risk, and testing of children and other relatives. The ethical obligations of clinicians start with the need to maintain competence in the face of rapidly evolving science. Clinicians should be able to identify patients within their practice who are candidates for genetic testing. When genetic susceptibility to cancer is identified, patients should be offered counseling and follow-up, with referral as appropriate, to ensure delivery of care consistent with current standards. When patients experience barriers to needed health care, clinicians should advocate for their needs. Clinicians must ensure the autonomy and informed decision-making of all members of cancer-prone families. Clinicians must also provide emotional support and accurate information about cancer risks and cancer risk reduction measures, including uncertainties. Teamwork among different specialties is important in addressing these challenges. PMID:16451774

Burke, Wylie; Press, Nancy

2006-02-01

396

Prestin in HEK cells is an obligate tetramer  

PubMed Central

The unusual membrane motor protein prestin is essential for mammalian hearing and for the survival of cochlear outer hair cells. While prestin has been demonstrated to be a homooligomer, by Western blot and FRET analyses, the stoichiometry of self association is unclear. Prestin, coupled to the enhanced green fluorescent protein, was synthesized and membrane targeted in human embryonic kidney cells by plasmid transfection. Fragments of membrane containing immobilized fluorescent molecules were isolated by osmotic lysis. Diffraction-limited fluorescent spots consistent in size with single molecules were observed. Under continuous excitation, the spots bleached to background in sequential and approximately equal-amplitude steps. The average step count to background levels was 2.7. A binomial model of prestin oligomerization indicated that prestin was most likely a tetramer, and that a fraction of the green fluorescent protein molecules was dark. As a positive control, the same procedure was applied to cells transfected with plasmids coding for the human cyclic nucleotide-gated ion channel A3 subunit (again coupled to the enhanced green fluorescent protein), which is an obligate tetramer. The average step count for this molecule was also 2.7. This result implies that in cell membranes prestin oligomerizes to a tetramer.

Nichols, Michael G.

2012-01-01

397

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

PubMed

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

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

2005-06-01

398

Interferon-gamma-activated primary enterocytes inhibit Toxoplasma gondii replication: a role for intracellular iron.  

PubMed

Toxoplasma gondii is an obligate intracellular parasite that infects a wide variety of nucleated cells in its numerous intermediate hosts including man. The oral route is the natural portal of entry of T. gondii. Ingested organisms are released from cysts or oocysts within the gastrointestinal tract and initially invade the intestinal epithelium. We show that T. gondii invades and proliferates in cultured primary rat enterocytes, obtained with an original procedure. Activation of the enterocytes with rat recombinant interferon-gamma (IFN-gamma) inhibits T. gondii replication, the inhibition being dose dependent. Neither nitrogen and oxygen derivatives nor tryptophan starvation appear to be involved in the inhibition of parasite replication by IFN-gamma. Experiments using Fe2+ salt, carrier and chelator indicate that intracellular T. gondii replication is iron dependent, suggesting that IFN-gamma-treated enterocytes inhibit T. gondii replication by limiting the availability of intracellular iron to the parasite. Our data show that enterocytes probably play a major role on mucosal surfaces as a first line of defence against this coccidia, and possibly other pathogens, through an immune mechanism. The results suggest that limiting the availability of iron could represent a broad antimicrobial mechanism through which the activated enterocytes exert control over intracellular pathogens. PMID:9767436

Dimier, I H; Bout, D T

1998-08-01

399

A mouse model of chronic bacterial lesions (a cotton trap) for studying oral bacteria - lymphocyte interactions  

Microsoft Academic Search

We established a mouse model of chronic bacterial infection (cotton trap) to get a deeper insight into interactions between immune cells and bacterial strains, that are most commonly isolated from periapical processes. We have used flow cytometry to identify the presence of intracellular cytokines of activated T cells collected from cotton traps, previously infected with different strains of bacteria and

Petra Hudler; Marija Gubina; Nataša Ihan Hren; Katja Seme; Tadej Malovrh; Nina Gale; Alojz Ihan

2000-01-01

400

A microfluidic device for physical trapping and electrical lysis of bacterial cells  

NASA Astrophysics Data System (ADS)

In this letter, we report a simple microfluidic device that integrates the capture of bacterial cells using a microscale bead array and the rapid electrical lysis for release of intracellular materials. We study the retention of Escherichia coli cells with different concentrations in this type of bead array and the optimal electrical parameters for the electroporative release of intracellular proteins. Our design provides a simple solution to the extraction of intracellular materials from a bacterial cell population based entirely on physical methods without applying chemical or biological reagents.

Bao, Ning; Lu, Chang

2008-05-01

401

Cellular reprogramming by gram-positive bacterial components: a review.  

PubMed

LPS tolerance has been the focus of extensive scientific and clinical research over the last several decades in an attempt to elucidate the sequence of changes that occur at a molecular level in tolerized cells. Tolerance to components of gram-positive bacterial cell walls such as bacterial lipoprotein and lipoteichoic acid is a much lesser studied, although equally important, phenomenon. This review will focus on cellular reprogramming by gram-positive bacterial components and examines the alterations in cell surface receptor expression, changes in intracellular signaling, gene expression and cytokine production, and the phenomenon of cross-tolerance. PMID:16885502

Buckley, Julliette M; Wang, Jiang Huai; Redmond, H Paul

2006-08-02

402

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

403

Pharmacology of intracellular signalling pathways  

PubMed Central

This article provides a brief and somewhat personalized review of the dramatic developments that have occurred over the last 45 years in our understanding of intracellular signalling pathways associated with G-protein-coupled receptor activation. Signalling via cyclic AMP, the phosphoinositides and Ca2+ is emphasized and these systems have already been revealed as new pharmacological targets. The therapeutic benefits of most of such targets are, however, yet to be realized, but it is certain that the discipline of pharmacology needs to widen its boundaries to meet these challenges in the future.

Nahorski, Stefan R

2006-01-01

404

Bacterial symbionts in insects: balancing life and death  

Microsoft Academic Search

Arthropods, particularly insects, form successful long-term symbioses with endosymbiotic bacteria. The associations between insects and endosymbionts are re- markably stable; many stretch back several hundred million years in evolutionary time. With the exception, perhaps, of the filarial nematodes no other group of metazoans shows such a proclivility for their intracellular symbionts. The identification and classification of bacterial symbionts and hosts

Harriet L. Harris; Lesley J. Brennan; B. Andrew Keddie; Henk R. Braig

2010-01-01

405

50 CFR 80.91 - What is a Federal obligation of funds and how does it occur?  

Code of Federal Regulations, 2011 CFR

...Federal obligation of funds and how does it occur? 80.91 Section 80.91 Wildlife...Federal obligation of funds and how does it occur? An obligation of funds is...assistance to use the funds available to it under the Acts and commits to provide...

2011-10-01

406

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

407

Real-Time monitoring of intracellular wax ester metabolism  

PubMed Central

Background Wax esters are industrially relevant molecules exploited in several applications of oleochemistry and food industry. At the moment, the production processes mostly rely on chemical synthesis from rather expensive starting materials, and therefore solutions are sought from biotechnology. Bacterial wax esters are attractive alternatives, and especially the wax ester metabolism of Acinetobacter sp. has been extensively studied. However, the lack of suitable tools for rapid and simple monitoring of wax ester metabolism in vivo has partly restricted the screening and analyses of potential hosts and optimal conditions. Results Based on sensitive and specific detection of intracellular long-chain aldehydes, specific intermediates of wax ester synthesis, bacterial luciferase (LuxAB) was exploited in studying the wax ester metabolism in Acinetobacter baylyi ADP1. Luminescence was detected in the cultivation of the strain producing wax esters, and the changes in signal levels could be linked to corresponding cell growth and wax ester synthesis phases. Conclusions The monitoring system showed correlation between wax ester synthesis pattern and luminescent signal. The system shows potential for real-time screening purposes and studies on bacterial wax esters, revealing new aspects to dynamics and role of wax ester metabolism in bacteria.

2011-01-01

408

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

Code of Federal Regulations, 2013 CFR

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

2013-04-01

409

25 CFR 163.42 - Obligated service and breach of contract.  

Code of Federal Regulations, 2013 CFR

...Forestry Education, Education Assistance, Recruitment and Training § 163.42 Obligated...scholarship program. (4) Postgraduation recruitment program âAmount plus interest equal...the Secretary under the postgraduation recruitment program. (5) Postgraduate...

2013-04-01

410

25 CFR 163.42 - Obligated service and breach of contract.  

Code of Federal Regulations, 2011 CFR

...Forestry Education, Education Assistance, Recruitment and Training § 163.42 Obligated...scholarship program. (4) Postgraduation recruitment program âAmount plus interest equal...the Secretary under the postgraduation recruitment program. (5) Postgraduate...

2011-04-01

411

12 CFR 366.13 - What is my obligation regarding confidential information?  

Code of Federal Regulations, 2013 CFR

... FEDERAL DEPOSIT INSURANCE CORPORATION REGULATIONS AND STATEMENTS OF GENERAL POLICY MINIMUM STANDARDS OF INTEGRITY AND FITNESS FOR AN FDIC CONTRACTOR § 366.13 What is my obligation regarding confidential information? (a) Neither you...

2013-01-01

412

43 CFR 3287.2 - When may BLM grant a suspension of unit obligations?  

Code of Federal Regulations, 2012 CFR

...suspension of initial drilling obligations due to a unit operator's inability to obtain an electrical sales contract, or when poor economics affect the electrical generation market, limiting the opportunity to obtain a viable sales contract. BLM may grant a...

2012-10-01

413

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

Code of Federal Regulations, 2012 CFR

...21004 Section 1.21004 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Competitive Bidding for Universal Service Support § 1.21004 Winning bidder's obligation to apply for...

2012-10-01

414

31 CFR 535.438 - Standby letters of credit, performance or payment bonds and similar obligations.  

Code of Federal Regulations, 2013 CFR

...performance or payment bonds and similar obligations. 535.438 Section 535.438 Money and Finance: Treasury Regulations Relating...ASSETS CONTROL REGULATIONS Interpretations § 535.438 Standby letters of credit, performance or...

2013-07-01

415

Parks and Recreation: Obligations and Outlays from the Land and Water Conservation Fund.  

National Technical Information Service (NTIS)

The fact sheet presents Land and Water Conservation Fund (LWCF) obligations and outlays for fiscal years 1976 through 1985. A description of the legislative authorities, restrictions, and prohibitions governing recreational fees charged by federal agencie...

1986-01-01

416

12 CFR 1510.5 - How does the Funding Corporation make interest payments on its obligations?  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false How does the Funding Corporation make interest payments on its obligations...Banking DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION RESOLUTION FUNDING CORPORATION OPERATIONS § 1510.5 How...

2012-01-01

417

12 CFR 1510.5 - How does the Funding Corporation make interest payments on its obligations?  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false How does the Funding Corporation make interest payments on its obligations...Banking DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION RESOLUTION FUNDING CORPORATION OPERATIONS § 1510.5 How...

2010-01-01

418

12 CFR 1510.5 - How does the Funding Corporation make interest payments on its obligations?  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false How does the Funding Corporation make interest payments on its obligations...Banking DEPARTMENT OF THE TREASURY RESOLUTION FUNDING CORPORATION RESOLUTION FUNDING CORPORATION OPERATIONS § 1510.5 How...

2009-01-01

419

Federal Obligations for Applied Research Keep Pace with Those for Basic Research  

NSF Publications Database

... for Applied Research Keep Pace with Those for Basic Research (April 27, 1998) This data brief ... the major findings on Federal obligations for research and development (R&D) and R&D plant for ...

420

77 FR 12906 - Notice of Release From Federal Grant Assurance Obligations at Fresno Yosemite International...  

Federal Register 2010, 2011, 2012, 2013

...Obligations at Fresno Yosemite International Airport, Fresno, CA AGENCY: Federal Aviation...ACTION: Notice of request to release airport land...release of approximately 16.02 acres of airport property at the Fresno Yosemite...

2012-03-02

421

21 CFR 312.52 - Transfer of obligations to a contract research organization.  

Code of Federal Regulations, 2013 CFR

...DRUG APPLICATION Responsibilities of Sponsors and Investigators § 312.52 Transfer...contract research organization. (a) A sponsor may transfer responsibility for...organization that assumes any obligation of a sponsor shall comply with the specific...

2013-04-01

422

31 CFR 541.407 - Payments from blocked accounts to satisfy obligations prohibited.  

Code of Federal Regulations, 2013 CFR

... Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY ZIMBABWE SANCTIONS REGULATIONS Interpretations § 541.407 Payments from blocked accounts to satisfy obligations...

2013-07-01

423

12 CFR 615.5102 - Issuance of debt obligations through the Funding Corporation.  

Code of Federal Regulations, 2013 CFR

...Issuance of debt obligations through the Funding Corporation. 615.5102 Section 615...ADMINISTRATION FARM CREDIT SYSTEM FUNDING AND FISCAL AFFAIRS, LOAN POLICIES AND OPERATIONS, AND FUNDING OPERATIONS Issuance of Bonds,...

2013-01-01

424

31 CFR 548.407 - Payments from blocked accounts to satisfy obligations prohibited.  

Code of Federal Regulations, 2010 CFR

... Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY BELARUS SANCTIONS REGULATIONS Interpretations § 548.407 Payments from blocked accounts to satisfy obligations...

2010-07-01

425

28 CFR 811.5 - Commencement of the obligation to register.  

Code of Federal Regulations, 2013 CFR

... (a) A sex offender's obligation to register starts when the sex offender is found guilty or not guilty by reason of insanity of a registration offense or is determined to be a sexual psychopath. However, CSOSA may suspend registration...

2013-07-01

426

34 CFR 535.57 - How shall the fellowship recipient account for the obligation?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false How shall the fellowship recipient account for the obligation...EDUCATION BILINGUAL EDUCATION: GRADUATE FELLOWSHIP PROGRAM What Conditions Must Be Met by Fellows? § 535.57 How shall the fellowship recipient account for the...

2010-07-01

427

34 CFR 535.57 - How shall the fellowship recipient account for the obligation?  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false How shall the fellowship recipient account for the obligation...EDUCATION BILINGUAL EDUCATION: GRADUATE FELLOWSHIP PROGRAM What Conditions Must Be Met by Fellows? § 535.57 How shall the fellowship recipient account for the...

2013-07-01

428

34 CFR 535.57 - How shall the fellowship recipient account for the obligation?  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false How shall the fellowship recipient account for the obligation...EDUCATION BILINGUAL EDUCATION: GRADUATE FELLOWSHIP PROGRAM What Conditions Must Be Met by Fellows? § 535.57 How shall the fellowship recipient account for the...

2009-07-01

429

Constitutional Law: The Obligation of a State School Newspaper to Accept Advertising  

ERIC Educational Resources Information Center

|Analyzes the background behind the application of the state action doctrine to a state school newspaper and analyzes the results of such application on a paper's obligation to accept advertising. (Author)|

Siler, Harvey A.

1974-01-01

430

16 CFR 240.11 - Wholesaler or third party performance of seller's obligations.  

Code of Federal Regulations, 2013 CFR

...GUIDES AND TRADE PRACTICE RULES GUIDES FOR ADVERTISING ALLOWANCES AND OTHER MERCHANDISING PAYMENTS...its responsibility to comply with the law. Therefore, in contracting with an...ensure that its obligations under the law are in fact...

2013-01-01

431

31 CFR 546.407 - Payments from blocked accounts to satisfy obligations prohibited.  

Code of Federal Regulations, 2013 CFR

... Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS Interpretations § 546.407 Payments from blocked accounts to satisfy obligations...

2013-07-01

432

77 FR 7108 - Affirmative Action and Nondiscrimination Obligations of Contractors and Subcontractors Regarding...  

Federal Register 2010, 2011, 2012, 2013

...Part 60-741 RIN 1250-AA02 Affirmative Action and Nondiscrimination Obligations...implementing the nondiscrimination and affirmative action regulations of section 503...proposed rule entitled, ``Affirmative Action and Nondiscrimination...

2012-02-10

433

76 FR 36482 - Affirmative Action and Nondiscrimination Obligations of Contractors and Subcontractors Regarding...  

Federal Register 2010, 2011, 2012, 2013

...and 60-300 RIN 1250-AA00 Affirmative Action and Nondiscrimination Obligations...regulations implementing the affirmative action provisions of the Vietnam Era...proposed rule entitled ``Affirmative Action and Nondiscrimination...

2011-06-22

434

75 FR 43116 - Affirmative Action and Nondiscrimination Obligations of Contractors and Subcontractors...  

Federal Register 2010, 2011, 2012, 2013

...Part 60-741 RIN 1250-AA02 Affirmative Action and Nondiscrimination Obligations...Subcontractors; Evaluation of Affirmative Action Provisions Under Section 503...how OFCCP can strengthen the affirmative action requirements of the...

2010-07-23

435

Moral obligation or moral support for high-tech home care.  

PubMed

We ordinarily think of parents having an almost total obligation for the care of their children, but one can imagine a mother less than eager to care for a semi-comatose teenager who overdosed on drugs.... To insist today that individuals have a moral obligation to care for their children, siblings, or parents overlooks the fact that many, perhaps most, people want to care for their loved ones. PMID:11659836

Noddings, Nel

436

Complete denitrification in coculture of obligately chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria from a hypersaline soda lake.  

PubMed

Eight anaerobic enrichment cultures with thiosulfate as electron donor and nitrate as electron acceptor were inoculated with sediment samples from hypersaline alkaline lakes of Wadi Natrun (Egypt) at pH 10; however, only one of the cultures showed stable growth with complete nitrate reduction to dinitrogen gas. The thiosulfate-oxidizing culture subsequently selected after serial dilution developed in two phases. Initially, nitrate was mostly reduced to nitrite, with a coccoid morphotype prevailing in the culture. During the second stage, nitrite was reduced to dinitrogen gas, accompanied by mass development of thin motile rods. Both morphotypes were isolated in pure culture and identified as representatives of the genus Thioalkalivibrio, which includes obligately autotrophic sulfur-oxidizing haloalkaliphilic species. Nitrate-reducing strain ALEN 2 consisted of large nonmotile coccoid cells that accumulated intracellular sulfur. Its anaerobic growth with thiosulfate, sulfide, or polysulfide as electron donor and nitrate as electron acceptor resulted in the formation of nitrite as the major product. The second isolate, strain ALED, was able to grow anaerobically with thiosulfate as electron donor and nitrite or nitrous oxide (but not nitrate) as electron acceptor. Overall, the action of two different sulfur-oxidizing autotrophs resulted in the complete, thiosulfate-dependent denitrification of nitrate under haloalkaliphilic conditions. This process has not yet been demonstrated for any single species of chemolithoautotrophic sulfur-oxidizing haloalkaliphiles. PMID:12827218

Sorokin, Dimitry Y; Antipov, Alexey N; Kuenen, J Gijs

2003-06-24

437

Dual mechanisms of metabolite acquisition by the obligate intracytosolic pathogen Rickettsia prowazekii reveal novel aspects of triose phosphate transport.  

PubMed

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

Frohlich, Kyla M; Audia, Jonathon P

2013-06-14

438

Bacterial Gene Transfer  

NSDL National Science Digital Library

This resource provides detailed instructions for carrying out several laboratory exercises relating to bacterial transformation and conjugation. In this multi-session experiment, students are exposed to various techniques in microbiology, including bacterial transformation and assay and sterile techniques.

Roberta Ellington (Northwestern University;); John Mordacq (Northwestern University;)

1991-01-01

439

Evolution of bacterial genomes.  

PubMed

This review examines evolution of bacterial genomes with an emphasis on RNA based life, the transition to functional DNA and small evolving genomes (possible plasmids) that led to larger, functional bacterial genomes. PMID:9111921

Trevors, J T

1997-03-01

440

The bacterial actin nucleator protein ActA of Listeria monocytogenes contains multiple binding sites for host microfilament proteins  

Microsoft Academic Search

Background: Several intracellular pathogens, including Listeria monocytogenes, use components of the host actin-based cytoskeleton for intracellular movement and for cell-to-cell spread. These bacterial systems provide relatively simple model systems with which to study actin-based motility. Genetic analysis of L. monocytogenes led to the identification of the 90 kD surface-bound ActA polypeptide as the sole bacterial factor required for the initiation

Susanne Pistor; Trinad Chakraborty; Ulrich Walter; Jürgen Wehland

1995-01-01

441

Transient transformation of the obligate biotrophic rust fungus Uromyces fabae using biolistics.  

PubMed

Obligate biotrophic pathogens like the rust fungi are important plant pathogens causing enormous losses on food, forage and biomass crops. The analysis of the molecular details underlying obligate biotrophic host-parasite interactions is mainly hampered by the fact that no system for transformation is available for most obligate biotrophic organisms. Here we report the transient transformation of Uromyces fabae, an obligate biotrophic rust fungus using a biolistic approach. Biolistic bombardment of U. fabae urediospores was used to deliver different color markers (?-glucuronidase (GUS), intron green fluorescent protein (iGFP) and red fluorescent protein (DsRed) and/or a selection marker. Endogenous regulatory elements from U. fabae plasma membrane ATPase (Uf-PMA1) were used to drive expression of the transgenes. In addition to the delivery of color markers, an in planta selection procedure using the fungicide Carboxin was established allowing the propagation of transformants. In addition to mere cytoplasmic expression of the color markers, a nuclear localization signal was fused to DsRed (pRV115-NLS) targeting the fluorescent marker protein to the nuclei. A procedure for the genetic modification of U. fabae was established. The method can be easily adapted for use with other obligate biotrophic fungi. This provides the basis for a more in depth analysis of the molecular principles governing the obligate biotrophic lifestyle. PMID:21724169

Djulic, Alma; Schmid, Annette; Lenz, Heike; Sharma, Pia; Koch, Christin; Wirsel, Stefan G R; Voegele, Ralf T

2011-04-09

442

Saying sorry: Shifting obligation after conciliatory acts satisfies perpetrator group members.  

PubMed

How are intergroup conciliatory acts (apologies and reparations) evaluated by members of the perpetrator group offering them? This research tests whether these outcomes can be predicted by obligation shifting: the perception that a conciliatory act has shifted the onus away from the perpetrators and onto the victim group. Four experiments in different contexts examined 3 possible outcomes for members of the perpetrator group: satisfaction with the act, negative feelings toward the victims, and support for future assistance. Across all 4 experiments, perceptions of obligation shifting predicted satisfaction with conciliatory acts, as did the perception that the ingroup's image had improved. Furthermore, obligation shifting alone related to more negative feelings about the victims and predicted reduced support for further acts of assistance. Image improvement perceptions did not show these effects, and sometimes were related to less negative feelings about the victims. Directly manipulating impressions of obligation shifting and image improvement (Experiment 3) showed these relationships were causal. When there were differences between types of acts on the 3 outcome variables, obligation shifting and image perceptions mediated these relationships. The negative implications of obligation shifting, as well as the more encouraging role of image improvement perceptions, are discussed. (PsycINFO Database Record (c) 2013 APA, all rights reserved). PMID:23773047

Zaiser, Erica; Giner-Sorolla, Roger

2013-06-17

443

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.

Rohde, Kyle H.; Veiga, Diogo F. T.; Caldwell, Shannon; Balazsi, Gabor; Russell, David G.

2012-01-01

444

Intracellularly induced cyclophilins play an important role in stress adaptation and virulence of Brucella abortus.  

PubMed

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

Roset, Mara S; García Fernández, Lucía; DelVecchio, Vito G; Briones, Gabriel

2012-12-10

445

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.

Garcia Fernandez, Lucia; DelVecchio, Vito G.; Briones, Gabriel

2013-01-01

446

Rate of Gene Transfer From Mitochondria to Nucleus: Effects of Cytoplasmic Inheritance System and Intensity of Intracellular Competition  

Microsoft Academic Search

Endosymbiotic theory states that mitochondria originated as bacterial intracellular symbionts, the size of the mitochondrial genome gradually reducing over a long period owing to, among other things, gene transfer from the mitochondria to the nucleus. Such gene transfer was observed in more genes in animals than in plants, implying a higher transfer rate of animals. The evolution of gene transfer

Atsushi Yamauchi

2005-01-01

447

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

Microsoft Academic Search

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

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

2000-01-01

448

Thioredoxin 80-Activated-Monocytes (TAMs) Inhibit the Replication of Intracellular Pathogens  

Microsoft Academic Search

BackgroundThioredoxin 80 (Trx80) is an 80 amino acid natural cleavage product of Trx, produced primarily by monocytes. Trx80 induces differentiation of human monocytes into a novel cell type, named Trx80-activated-monocytes (TAMs).Principal FindingsIn this investigation we present evidence for a role of TAMs in the control of intracellular bacterial infections. As model pathogens we have chosen Listeria monocytogenes and Brucella abortus

Ximena Cortes-Bratti; Eugénie Bassères; Fabiola Herrera-Rodriguez; Silvia Botero-Kleiven; Giuseppe Coppotelli; Jens B. Andersen; Maria G. Masucci; Arne Holmgren; Esteban Chaves-Olarte; Teresa Frisan; Javier Avila-Cariño

2011-01-01

449

Naip5 Affects Host Susceptibility to the Intracellular Pathogen Legionella pneumophila  

Microsoft Academic Search

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

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

2003-01-01

450

NOD2, an intracellular innate immune sensor involved in host defense and Crohn's disease  

Microsoft Academic Search

Nucleotide-binding oligomerization domain 2 (NOD2) is an intracellular sensor for small peptides derived from the bacterial cell wall component, peptidoglycan. Recent studies have uncovered unexpected functions of NOD2 in innate immune responses such as induction of type I interferon and facilitation of autophagy; moreover, they have disclosed extensive cross-talk between NOD2 and Toll-like receptors, which has an indispensable role both

W Strober; T Watanabe

2011-01-01

451

Brucella abortus intracellular survival and intercellular trafficking  

Microsoft Academic Search

Brucella spp. are host specific facultative intracellular pathogens. Brucella abortus is responsible for causing abortions in cattle and is also able to cause disease in humans. Brucella internalization and intracellular trafficking varies depending on whether the bacterium was opsonized or non-opsonized with serum immunoglobulin. Interferon-gamma has been shown to be critical for the control of B. abortus infection in vivo

Jennifer Ann Ritchie

2011-01-01

452

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

453

Obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea.  

SciTech Connect

Closing report for project DOE-FG02-03ER15436. The project studied obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea. Nitrosomonas europaea can obtain all of its energy and reductant for growth from the oxidation of ammonia to nitrite and is, therefore, classified as a chemolithotroph. This bacterium is also an autotroph, which can derive all cellular carbon from carbon dioxide. N. europaea seems incapable of growth with other carbon or energy sources. This restricted capability is surprising given that ammonia is a poor energy source. The main goal of the project was to examine the basis of autotrophy in N. europaea or, thought of another way, to determine the barriers to heterotrophy. The approach was enabled by the N. europaea genome sequence, stimulating new ways of thinking about this physiological paradox—an insistence on a single, albeit poor, energy source. Objective 1 was to examine the expression and regulation of the genes coding for alpha-ketoglutarate dehydrogenase, determine if the enzyme’s activity is present, and determine whether alteration of the expression levels influences autotrophic growth. Although Nitrosomonas europaea lacks measurable alpha-ketoglutarate dehydrogenase activity, the genome sequence revealed the presence of the genes encoding the enzyme. A knockout mutation was created in the sucA gene encoding the E1 subunit. Compared to wild-type cells, the mutant strain showed an accelerated loss of ammonia monooxygenase and hydroxylamine oxidoreductase activities upon entering stationary phase. In addition, unlike wild-type cells, the mutant strain showed a marked lag in the ability to resume growth in response to pH adjustments in late stationary phase. The results were published in Hommes N.G., Kurth E. G., Sayavedra-Soto L.A., and Arp D.J. (2006) Disruption of sucA, which encodes a subunit of alpha-ketoglutarate dehydrogenase, affects the survival of Nitrosomonas europaea in stationary phase. Journal of Bacteriology 188:343-347. Objective 2 was to determine the basis of fructose stimulation of growth on ammonia, examine fructose metabolism, and determine the impact of other compounds on growth on ammonia. Previous studies showed that N. europaea can utilize limited amounts of certain organic compounds, including amino acids, pyruvate, and acetate, although no organic compound has been reported to support the growth of N. europaea. The genomic sequence of N. europaea revealed a potential permease for fructose. N. europaea utilized fructose and other compounds as carbon sources to support growth. Cultures were incubated in the presence of fructose or other organic compounds in sealed bottles purged of CO(2). In these cultures, addition of either fructose or pyruvate as the sole carbon source resulted in a two- to threefold increase in optical density and protein content in 3 to 4 days. Studies with [(14)C]fructose showed that >90% of the carbon incorporated by the cells during growth was derived from fructose. Cultures containing mannose, glucose, glycerol, mannitol, citrate, or acetate showed little or no growth. N. europaea was not able to grow with fructose as an energy source, although the presence of fructose did provide an energy benefit to the cells. These results show that N. europaea can be grown in carbon dioxide free medium by using fructose and pyruvate as carbon sources and may now be considered a facultative chemolithoorganotroph. The results were published in Hommes N.G., Sayavedra-Soto L.A. and Arp. D.J. (2003). Chemolithotrophic growth of Nitrosomonas europaea on fructose. Journal of Bacteriology. 185:6809-2773. Objective 3 attempted to grow N. europaea heterotrophically through pathways predicted by the genome. Experiments with mutant strains and complementation studies were performed to test whether N. europaea can utilize other carbon sources. N. europaea was not able to grow heterotrophically in the conditions tested in this objective.

Daniel James Arp; Luis Alberto Sayavedra-Soto

2006-01-01

454

A differential fluorescence-based genetic screen identifies Listeria monocytogenes determinants required for intracellular replication.  

PubMed

Listeria monocytogenes is a Gram-positive, facultative intracellular pathogen capable of causing severe invasive disease with high mortality rates in humans. While previous studies have largely elucidated the bacterial and host cell mechanisms necessary for invasion, vacuolar escape, and subsequent cell-to-cell spread, the L. monocytogenes factors required for rapid replication within the restrictive environment of the host cell cytosol are poorly understood. In this report, we describe a differential fluorescence-based genetic screen utilizing fluorescence-activated cell sorting (FACS) and high-throughput microscopy to identify L. monocytogenes mutants defective in optimal intracellular replication. Bacteria harboring deletions within the identified gene menD or pepP were defective for growth in primary murine macrophages and plaque formation in monolayers of L2 fibroblasts, thus validating the ability of the screening method to identify intracellular replication-defective mutants. Genetic complementation of the menD and pepP deletion strains rescued the in vitro intracellular infection defects. Furthermore, the menD deletion strain displayed a general extracellular replication defect that could be complemented by growth under anaerobic conditions, while the intracellular growth defect of this strain could be complemented by the addition of exogenous menaquinone. As prior studies have indicated the importance of aerobic metabolism for L. monocytogenes infection, these findings provide further evidence for the importance of menaquinone and aerobic metabolism for L. monocytogenes pathogenesis. Lastly, both the menD and pepP deletion strains were attenuated during in vivo infection of mice. These findings demonstrate that the differential fluorescence-based screening approach provides a powerful tool for the identification of intracellular replication determinants in multiple bacterial systems. PMID:23687268

Perry, Kyle J; Higgins, Darren E

2013-05-17

455

[The right to self-determination versus the obligation to protect one's health].  

PubMed

"Individual responsibility" and the abidance by any "health-related obligations" are key words of the present political and legal German healthcare debate. In the process of adjusting the German welfare state by focussing the ideal allocation of common health resources patients who do not meet their "health-related obligations" are thus expected to accept cutbacks in medical care services. However, from the perspective of constitutional law there is no "health-related obligation" deriving from the German constitution - the right to self-determination guaranteed in Art. 2 Sect. 2 Sent. 1 of the German constitution has not been amended to impose a corresponding duty. Hence, health-related obligations may only refer to indirect ways of exercising individual responsibility, no more and no less. The present article highlights the few possibilities which the German constitution provides for the implementation of "health-related obligations" and reminds us of the conceptual aspects which have to be considered by the legislator. PMID:19645343

Höfling, Wolfram

2009-01-01

456

[Bacterial vaginitis: general overview].  

PubMed

Bacteria are the most frequently detected agents in women, clinically complaining of vaginal discharge. The studies have shown that the vaginal microflora of women with bacterial vaginitis have altered from Lactobacillus spp. to various anaerobic bacteria. Gardnerella vaginalis is found in vaginal flora of women with bacterial vaginitis as well as in healthy women, while anaerobic bacteria such as Mobiluncus and Prevotella are the causative agents for bacterial vaginosis. For the laboratory diagnosis of bacterial vaginitis, direct microscopy is one of the most commonly used methods, and for this purpose cervicovaginal smears are examined by staining Papanicolaou and Gram stains. Because of the demonstration of bacterial vaginitis in association with the obstetric diseases such as preterm labor and postpartum endometritis, is a risk factor, its importance has increased recently. In this review article, the microorganisms that cause bacterial vaginitis, their biological characteristics, and the diagnostic laboratory methods of infection, have been discussed. PMID:12838684

Demirezen, Sayeste

2003-01-01

457

A cross-cultural study of noblesse oblige in economic decision-making.  

PubMed

A cornerstone of economic theory is that rational agents are self-interested, yet a decade of research in experimental economics has shown that economic decisions are frequently driven by concerns for fairness, equity, and reciprocity. One aspect of other-regarding behavior that has garnered attention is noblesse oblige, a social norm that obligates those of higher status to be generous in their dealings with those of lower status. The results of a cross-cultural study are reported in which marked noblesse oblige was observed on a reciprocal-contract decision-making task. Participants from seven countries that vary along hierarchical and individualist/collectivist social dimensions were more tolerant of non-reciprocation when they adopted a high-ranking perspective compared with a low-ranking perspective. PMID:23749462

Fiddick, Laurence; Cummins, Denise Dellarosa; Janicki, Maria; Lee, Sean; Erlich, Nicole

2013-09-01

458

Gradations of Researchers' Obligation to Provide Ancillary Care for HIV/AIDS in Developing Countries  

PubMed Central

Three principal factors affect the stringency of medical researchers’ obligation to provide antiretroviral treatment to participants in non-HIV/AIDS studies that are conducted in developing countries: (1) the centrality of HIV/AIDS to the study design, (2) the extent of the researcher–participant interaction, and (3) the cost relative to the study budget. I provide a basis for assessing the comparative stringency of the researchers’ obligation to provide this type of ancillary care. Practically, given the range of possible responses to study participants’ needs, calibrating the researcher’s responsibility to provide ancillary care is a useful step in ethical analysis. Theoretically, a gradation of obligation suggests how research ethics committees or institutional review boards can take multiple, potentially conflicting ethical factors into account without undertaking spurious efforts to quantify their importance.

Richardson, Henry S.

2007-01-01

459

An obligation to provide abortion services: what happens when physicians refuse?  

PubMed Central

Access to abortion services in the United States continues to decline. It does so not because of significant changes in legislation or court rulings but because fewer and fewer physicians wish to perform abortions and because most states now have "conscientious objection" legislation that makes it easy for physicians to refuse to do so. We argue in this paper that physicians have an obligation to perform all socially sanctioned medical services, including abortions, and thus that the burden of justification lies upon those who wish to be excused from that obligation. That is, such persons should have to show how requiring them to perform abortions would represent a serious threat to their fundamental moral or religious beliefs. We use current California law as an example of legislation that does not take physicians' obligations into account and thus allows them too easily to declare conscientious objection.

Meyers, C; Woods, R D

1996-01-01

460

Demonstrating Bacterial Flagella.  

ERIC Educational Resources Information Center

|Describes an effective laboratory method for demonstrating bacterial flagella that utilizes the Proteus mirabilis organism and a special harvesting technique. Includes safety considerations for the laboratory exercise. (MDH)|

Porter, John R.; And Others

1992-01-01

461

Scansytem Bacterial Detection Device  

Center for Biologics Evaluation and Research (CBER)

... Scansytem Bacterial Detection Device. Applicant: Hemosystem, SA, Richmond, VA. 510(k) number: BK040031. Product: Scansytem ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

462

Autophagy targeting of Listeria monocytogenes and the bacterial countermeasure.  

PubMed

Autophagy acts as an intrinsic defense system against intracellular bacterial survival. Recently, multiple cellular pathways that target intracellular bacterial pathogens to autophagy have been described. These include the Atg5/LC3 pathway, which targets Shigella, the ubiquitin (Ub)-NDP52-LC3 pathway, which targets Group A Streptococcus (GAS) and Salmonella typhimurium, the Ub-p62-LC3 pathway, which targets Mycobacterium tuberculosis, Listeria monocytogenes and S. typhimurium, and the diacylglycerol-dependent pathway, which targets S. typhimurium. In addition, the bacterial invasion process is targeted by the NOD1 or NOD2-Atg16LLC3 pathway. Bacterial pathogens with an intracytosolic lifestyle, i.e., those capable of inducing actin polymerization and cell-to-cell spreading, also employ diverse tactics to evade autophagic recognition. Thus, Shigella, L. monocytogenes and Burkholderia pseudomallei deploy highly evolved systems to evade autophagic recognition and growth restriction. Here, we briefly review current knowledge of host recognition of L. monocytogenes by the innate immune system, and highlight how autophagic recognition by the host is overcome by bacterial countermeasures. PMID:21193840

Ogawa, Michinaga; Yoshikawa, Yuko; Mimuro, Hitomi; Hain, Torsten; Chakraborty, Trinad; Sasakawa, Chihiro

2011-03-01

463

Manganese (Mn) Oxidation Increases Intracellular Mn in Pseudomonas putida GB-1  

PubMed Central

Bacterial manganese (Mn) oxidation plays an important role in the global biogeochemical cycling of Mn and other compounds, and the diversity and prevalence of Mn oxidizers have been well established. Despite many hypotheses of why these bacteria may oxidize Mn, the physiological reasons remain elusive. Intracellular Mn levels were determined for Pseudomonas putida GB-1 grown in the presence or absence of Mn by inductively coupled plasma mass spectrometry (ICP-MS). Mn oxidizing wild type P. putida GB-1 had higher intracellular Mn than non Mn oxidizing mutants grown under the same conditions. P. putida GB-1 had a 5 fold increase in intracellular Mn compared to the non Mn oxidizing mutant P. putida GB-1-007 and a 59 fold increase in intracellular Mn compared to P. putida GB-1 ?2665 ?2447. The intracellular Mn is primarily associated with the less than 3 kDa fraction, suggesting it is not bound to protein. Protein oxidation levels in Mn oxidizing and non oxidizing cultures were relatively similar, yet Mn oxidation did increase survival of P. putida GB-1 when oxidatively stressed. This study is the first to link Mn oxidation to Mn homeostasis and oxidative stress protection.

Banh, Andy; Chavez, Valarie; Doi, Julia; Nguyen, Allison; Hernandez, Sophia; Ha, Vu; Jimenez, Peter; Espinoza, Fernanda; Johnson, Hope A.

2013-01-01

464

Manganese (Mn) Oxidation Increases Intracellular Mn in Pseudomonas putida GB-1.  

PubMed

Bacterial manganese (Mn) oxidation plays an important role in the global biogeochemical cycling of Mn and other compounds, and the diversity and prevalence of Mn oxidizers have been well established. Despite many hypotheses of why these bacteria may oxidize Mn, the physiological reasons remain elusive. Intracellular Mn levels were determined for Pseudomonas putida GB-1 grown in the presence or absence of Mn by inductively coupled plasma mass spectrometry (ICP-MS). Mn oxidizing wild type P. putida GB-1 had higher intracellular Mn than non Mn oxidizing mutants grown under the same conditions. P. putida GB-1 had a 5 fold increase in intracellular Mn compared to the non Mn oxidizing mutant P. putida GB-1-007 and a 59 fold increase in intracellular Mn compared to P. putida GB-1 ?2665 ?2447. The intracellular Mn is primarily associated with the less than 3 kDa fraction, suggesting it is not bound to protein. Protein oxidation levels in Mn oxidizing and non oxidizing cultures were relatively similar, yet Mn oxidation did increase survival of P. putida GB-1 when oxidatively stressed. This study is the first to link Mn oxidation to Mn homeostasis and oxidative stress protection. PMID:24147089

Banh, Andy; Chavez, Valarie; Doi, Julia; Nguyen, Allison; Hernandez, Sophia; Ha, Vu; Jimenez, Peter; Espinoza, Fernanda; Johnson, Hope A

2013-10-17

465

The evolution of obligate mutualism: if you can't beat 'em, join 'em.  

PubMed

Wolbachia is best known as a facultative endosymbiotic parasite, manipulating host reproduction. However, it has also evolved as an obligate mutualist at least twice. In a recent paper, Pannebakker et al. identify a possible mechanism for such a transition from facultative parasitism to obligate mutualism in a parasitic wasp in which Wolbachia are required for producing eggs (oogenesis). Their proposed mechanism suggests that compensatory evolution in the host to counter the harmful effects of Wolbachia is the basis of this evolutionary transition. PMID:17825952

Aanen, Duur K; Hoekstra, Rolf F

2007-09-07

466

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

467

Lysosomes and Intracellular Digestion in Sea Stars.  

National Technical Information Service (NTIS)

The study of lysosomes and intracellular digestion in sea stars seemed ideal. Echinoderms occupy an intermediate position in the phylogenetic progression from protozoan to mammal. A single sea star can cleanly provide a large amount of relatively homogeno...

G. S. Araki

1969-01-01

468

Intracellular Streptococcus pyogenes in Human Macrophages Display an Altered Gene Expression Profile  

PubMed Central

Streptococcus pyogenes is an important human pathogen, which has recently gained recognition as an intracellular microorganism during the course of severe invasive infections such as necrotizing fasciitis. Although the surface anchored M protein has been identified as a pivotal factor affecting phagosomal maturation and S. pyogenes survival within macrophages, the overall transcriptional profile required for the pathogen to adapt and persist intracellularly is as of yet unknown. To address this, the gene expression profile of S. pyogenes within human macrophages was determined and compared to that of extracellular bacteria using customized microarrays and real-time qRT-PCR. In order to model the early phase of infection involving adaptation to the intracellular compartment, samples were collected 2h post-infection. Microarray analysis revealed that the expression of 145 streptococcal genes was significantly altered in the intracellular environment. The majority of differentially regulated genes were associated with metabolic and energy-dependent processes. Key up-regulated genes in early phase intracellular bacteria were ihk and irr, encoding a two-component gene regulatory system (TCS). Comparison of gene expression of selected genes at 2h and 6h post-infection revealed a dramatic shift in response regulators over time with a down-regulation of ihk/irr genes concurring with an up-regulation of the covR/S TCS. In re-infection assays, intracellular bacteria from the 6h time point exhibited significantly greater survival within macrophages than did bacteria collected at the 2h time point. An isogenic S. pyogenes mutant deficient in ihk/irr displayed significantly reduced bacterial counts when compared to wild-type bacteria following infection of macrophages. The findings illustrate how gene expression of S. pyogenes during the intracellular life cycle is fine-tuned by temporal expression of specific two-component systems.

Hertzen, Erika; Johansson, Linda; Kansal, Rita; Hecht, Alexander; Dahesh, Samira; Janos, Marton; Nizet, Victor; Kotb, Malak; Norrby-Teglund, Anna

2012-01-01

469

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

PubMed Central

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

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

2009-01-01

470

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

471

Bacterial diversity in agroecosystems  

Microsoft Academic Search

All life forms rely on bacterial processes for their survival. Bacterial diversity is greater than the diversity of any other group of organisms. Bacteria are responsible for diverse metabolic functions that affect soil and plant health. Nutrient cycling, organic matter formation and decomposition, soil structure formation, and plant growth promotion are among the beneficial functions that bacteria perform. Deleterious effects

A. C. Kennedy

1999-01-01

472

Bacterial cell shape  

Microsoft Academic Search

Bacterial species have long been classified on the basis of their characteristic cell shapes. Despite intensive research, the molecular mechanisms underlying the generation and maintenance of bacterial cell shape remain largely unresolved. The field has recently taken an important step forward with the discovery that eukaryotic cytoskeletal proteins have homologues in bacteria that affect cell shape. Here, we discuss how

Matthew T. Cabeen; Christine Jacobs-Wagner

2005-01-01

473

Staphylococcus aureus promotes autophagy by decreasing intracellular cAMP levels.  

PubMed

Staphylococcus aureus is an intracellular bacterium responsible for serious infectious processes. This pathogen escapes from the phagolysosomal pathway into the cytoplasm, a strategy that allows intracellular bacterial replication and survival with the consequent killing of the eukaryotic host cell and spreading of the infection. S. aureus is able to secrete several virulence factors such as enzymes and toxins. Our recent findings indicate that the main virulence factor of S. aureus, the pore-forming toxin ?-hemolysin (Hla), is the secreted factor responsible for the activation of an alternative autophagic pathway. We have demonstrated that this noncanonical autophagic response is inhibited by artificially elevating the intracellular levels of cAMP. This effect is mediated by RAPGEF3/EPAC (Rap guanine nucleotide exchange factor (GEF)3/exchange protein activated by cAMP), a cAMP downstream effector that functions as a GEF for the small GTPase Rap. We have presented evidence that RAPGEF3 and RAP2B, through calpain activation, are the proteins involved in the regulation of Hla and S. aureus-induced autophagy. In addition, we have found that both, RAPGEF3 and RAP2B, are recruited to the S. aureus-containing phagosome. Of note, adding purified ?-toxin or infecting the cells with S. aureus leads to a decrease in intracellular cAMP levels, which promotes autophagy induction, a response that favors pathogen intracellular survival, as previously demonstrated. We have identified some key signaling molecules involved in the autophagic response upon infection with a bacterial pathogen, which have important implications in understanding innate immune defense mechanisms. PMID:23047465

Mestre, Maria Belén; Colombo, María Isabel

2012-10-09

474

Progress towards understanding the fate of plasmids in bacterial communities.  

PubMed

Plasmid-mediated horizontal gene transfer influences bacterial community structure and evolution. However, an understanding of the forces which dictate the fate of plasmids in bacterial populations remains elusive. This is in part due to the enormous diversity of plasmids, in terms of size, structure, transmission, evolutionary history and accessory phenotypes, coupled with the lack of a standard theoretical framework within which to investigate them. This review discusses how ecological factors, such as spatial structure and temporal fluctuations, shape both the population dynamics and the physical features of plasmids. Novel data indicate that larger plasmids are more likely to be harboured by hosts in complex environments. Plasmid size may therefore be determined by environmentally mediated fitness trade-offs. As the correlation between replicon size and complexity of environment is similar for plasmids and chromosomes, plasmids could be us