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Sample records for secretion system c-ring

  1. The Chlamydia type III secretion system C-ring engages a chaperone-effector protein complex.

    Directory of Open Access Journals (Sweden)

    Kris E Spaeth

    2009-09-01

    Full Text Available In Gram-negative bacterial pathogens, specialized chaperones bind to secreted effector proteins and maintain them in a partially unfolded form competent for translocation by type III secretion systems/injectisomes. How diverse sets of effector-chaperone complexes are recognized by injectisomes is unclear. Here we describe a new mechanism of effector-chaperone recognition by the Chlamydia injectisome, a unique and ancestral line of these evolutionarily conserved secretion systems. By yeast two-hybrid analysis we identified networks of Chlamydia-specific proteins that interacted with the basal structure of the injectisome, including two hubs of protein-protein interactions that linked known secreted effector proteins to CdsQ, the putative cytoplasmic C-ring component of the secretion apparatus. One of these protein-interaction hubs is defined by Ct260/Mcsc (Multiple cargo secretion chaperone. Mcsc binds to and stabilizes at least two secreted hydrophobic proteins, Cap1 and Ct618, that localize to the membrane of the pathogenic vacuole ("inclusion". The resulting complexes bind to CdsQ, suggesting that in Chlamydia, the C-ring of the injectisome mediates the recognition of a subset of inclusion membrane proteins in complex with their chaperone. The selective recognition of inclusion membrane proteins by chaperones may provide a mechanism to co-ordinate the translocation of subsets of inclusion membrane proteins at different stages in infection.

  2. Type VI secretion system.

    Science.gov (United States)

    Salomon, Dor; Orth, Kim

    2015-03-30

    Bacteria employ a variety of tools to survive in a competitive environment. Salomon and Orth describe one such tool-the Type 6 Secretion Systems used by bacteria to deliver a variety of toxins into competing cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Secret-key rates and privacy leakage in biometric systems

    NARCIS (Netherlands)

    Ignatenko, T.

    2009-01-01

    In this thesis both the generation of secret keys from biometric data and the binding of secret keys to biometric data are investigated. These secret keys can be used to regulate access to sensitive data, services, and environments. In a biometric secrecy system a secret key is generated or chosen

  4. A study on the sealing performance of metallic C-rings in reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Xiaohong, E-mail: jiaxh@mail.tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Chen, Huaming [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Li, Xinggen [Ningbo Tiansheng Sealing Packing Co., Ltd, Ningbo 315302 (China); Wang, Yuming [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Wang, Longke [Eaton Corporation, MN (United States)

    2014-10-15

    Highlights: • FE analysis on compression–resilience of metallic C-ring is performed and validated by experiments. • Model of RPV sealing system including the C-rings is developed. • Deformation data from factory hydraulic test of the RPV are used to verify the model. • C-rings’ behavior under designing condition is analyzed. • The model provides a reliable evaluation on the sealing performance of RPV. - Abstract: Double metallic C-rings are used in pressure vessel of pressurized water reactor (PWR) to seal the bolt-connected flanges. To evaluate the sealing performance, it is necessary to study both the C-rings’ intrinsic properties and their behavior in reactor pressure vessel (RPV) under various loading conditions. The compression–resilience property and linear load are the basic information to evaluate the performance of a well-designed C-ring's. An equivalent model of C-ring is constructed by means of ANSYS to analyze its intrinsic properties, and is also validated by experiments on scaled samples. This model is applied to develop a 2D-axisymmetric FE model of sealing system including RPV and C-rings with the consideration of nonlinear material, contacting problem and multiple coupled effects. The simulation results of RPV deformation under the hydraulic test condition agree well with the data of factory hydraulic test. With the verified model, an analysis under the designing condition is performed to study C-rings’ behavior in the RPV, and then provides a reliable evaluation on the sealing performance of RPV.

  5. Secret rate - Privacy leakage in biometric systems

    NARCIS (Netherlands)

    Ignatenko, T.; Willems, F.M.J.

    2009-01-01

    Ahlswede and Csiszár [1993] introduced the concept of secret sharing. In their source model two terminals observe two correlated sequences. It is the objective of the terminals to form a common secret by interchanging a public message (helper data) in such a way that the secrecy leakage is

  6. The ESX system in Bacillus subtilis mediates protein secretion.

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    Laura A Huppert

    Full Text Available Esat-6 protein secretion systems (ESX or Ess are required for the virulence of several human pathogens, most notably Mycobacterium tuberculosis and Staphylococcus aureus. These secretion systems are defined by a conserved FtsK/SpoIIIE family ATPase and one or more WXG100 family secreted substrates. Gene clusters coding for ESX systems have been identified amongst many organisms including the highly tractable model system, Bacillus subtilis. In this study, we demonstrate that the B. subtilis yuk/yue locus codes for a nonessential ESX secretion system. We develop a functional secretion assay to demonstrate that each of the locus gene products is specifically required for secretion of the WXG100 virulence factor homolog, YukE. We then employ an unbiased approach to search for additional secreted substrates. By quantitative profiling of culture supernatants, we find that YukE may be the sole substrate that depends on the FtsK/SpoIIIE family ATPase for secretion. We discuss potential functional implications for secretion of a unique substrate.

  7. In silico dissection of Type VII Secretion System components across

    Indian Academy of Sciences (India)

    Type VII Secretion System (T7SS) is one of the factors involved in virulence of Mycobacteriun tuberculosis H37Rv. Numerous research efforts have been made in the last decade towards characterizing the components of this secretion system. An extensive genome-wide analysis through compilation of isolated information ...

  8. Distribution and diversity of bacterial secretion systems across metagenomic datasets.

    Science.gov (United States)

    Barret, Matthieu; Egan, Frank; O'Gara, Fergal

    2013-02-01

    Bacteria can manipulate their surrounding environment through the secretion of proteins into other living organisms and into the extracellular milieu. In Gram stain negative bacteria this process is mediated by different types of secretion systems from type I through type VI secretion system (T1SS-T6SS). In this study the prevalence of these secretion systems in 312 publicly available microbiomes derived from a wide range of ecosystems was investigated by a gene-centric approach. Our analysis demonstrates that some secretion systems are over-represented in some specific samples. In addition, some T3SS and T6SS phylogenetic clusters were specifically enriched in particular ecological niches, which could indicate specific bacterial adaptation to these environments. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  9. Extracellular secretion of a recombinant therapeutic peptide by Bacillus halodurans utilizing a modified flagellin type III secretion system

    CSIR Research Space (South Africa)

    Berger, E

    2011-08-01

    Full Text Available further 3.5-fold increase in the secretion of recombinant peptide fusions. Conclusions: The type III flagellar secretion system of B. halodurans has been shown to successfully secrete a therapeutic peptide as a heterologous flagellin fusion. Improvements...

  10. Trade Secret Law and Information Systems: Can Your Students Keep a Secret?

    Science.gov (United States)

    Willey, Lorrie; Ford, Janet C.; White, Barbara Jo; Clapper, Danial L.

    2011-01-01

    The impact of intellectual property (IP) law on information systems (IS) professionals in business cannot be overstated. The IS 2010 model curriculum guidelines for undergraduate IS programs stress the importance of information security and knowledge about IP. While copyright and patents are the most well-known types of IP, another, trade secrets,…

  11. Total Synthesis of Bryostatins. Development of Methodology for Atom-Economic and Stereoselective Synthesis of the C-ring Subunit

    Science.gov (United States)

    Trost, Barry M.; Frontier, Alison J.; Thiel, Oliver R.; Yang, Hanbiao; Dong, Guangbin

    2012-01-01

    Bryostatins, a family of structurally complicated macrolides, exhibit an exceptional range of biological activities. The limited availability and structural complexity of these molecules makes development of an efficient total synthesis particularly important. This article describes our initial efforts towards the total synthesis of bryostatins, in which chemoselective and atom-economical methods for stereoselective assembly of the C-ring subunit were developed. A Pd-catalyzed tandem alkyne-alkyne coupling/6-endo-dig cyclization sequence was explored and successfully pursued in the synthesis of a dihydropyran ring system. Elaboration of this methodology ultimately led to a concise synthesis of the C-ring subunit of bryostatins. PMID:21793057

  12. Effective Information Systems: What's the Secret?

    Science.gov (United States)

    Kirkham, Sandi

    1994-01-01

    Argues that false assumptions about user needs implicit in methodologies for building information systems have resulted in inadequate and inflexible systems. Checkland's Soft Systems Methodology is examined as a useful alternative. Its fundamental features are described, and examples of models demonstrate how the methodology can facilitate…

  13. Type VI Secretion System Toxins Horizontally Shared between Marine Bacteria.

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    Dor Salomon

    2015-08-01

    Full Text Available The type VI secretion system (T6SS is a widespread protein secretion apparatus used by Gram-negative bacteria to deliver toxic effector proteins into adjacent bacterial or host cells. Here, we uncovered a role in interbacterial competition for the two T6SSs encoded by the marine pathogen Vibrio alginolyticus. Using comparative proteomics and genetics, we identified their effector repertoires. In addition to the previously described effector V12G01_02265, we identified three new effectors secreted by T6SS1, indicating that the T6SS1 secretes at least four antibacterial effectors, of which three are members of the MIX-effector class. We also showed that the T6SS2 secretes at least three antibacterial effectors. Our findings revealed that many MIX-effectors belonging to clan V are "orphan" effectors that neighbor mobile elements and are shared between marine bacteria via horizontal gene transfer. We demonstrated that a MIX V-effector from V. alginolyticus is a functional T6SS effector when ectopically expressed in another Vibrio species. We propose that mobile MIX V-effectors serve as an environmental reservoir of T6SS effectors that are shared and used to diversify antibacterial toxin repertoires in marine bacteria, resulting in enhanced competitive fitness.

  14. Proteomic Identification of Novel Secreted Antibacterial Toxins of the Serratia marcescens Type VI Secretion System*

    Science.gov (United States)

    Fritsch, Maximilian J.; Trunk, Katharina; Diniz, Juliana Alcoforado; Guo, Manman; Trost, Matthias; Coulthurst, Sarah J.

    2013-01-01

    It has recently become apparent that the Type VI secretion system (T6SS) is a complex macromolecular machine used by many bacterial species to inject effector proteins into eukaryotic or bacterial cells, with significant implications for virulence and interbacterial competition. “Antibacterial” T6SSs, such as the one elaborated by the opportunistic human pathogen, Serratia marcescens, confer on the secreting bacterium the ability to rapidly and efficiently kill rival bacteria. Identification of secreted substrates of the T6SS is critical to understanding its role and ability to kill other cells, but only a limited number of effectors have been reported so far. Here we report the successful use of label-free quantitative mass spectrometry to identify at least eleven substrates of the S. marcescens T6SS, including four novel effector proteins which are distinct from other T6SS-secreted proteins reported to date. These new effectors were confirmed as antibacterial toxins and self-protecting immunity proteins able to neutralize their cognate toxins were identified. The global secretomic study also unexpectedly revealed that protein phosphorylation-based post-translational regulation of the S. marcescens T6SS differs from that of the paradigm, H1-T6SS of Pseudomonas aeruginosa. Combined phosphoproteomic and genetic analyses demonstrated that conserved PpkA-dependent threonine phosphorylation of the T6SS structural component Fha is required for T6SS activation in S. marcescens and that the phosphatase PppA can reverse this modification. However, the signal and mechanism of PpkA activation is distinct from that observed previously and does not appear to require cell–cell contact. Hence this study has not only demonstrated that new and species-specific portfolios of antibacterial effectors are secreted by the T6SS, but also shown for the first time that PpkA-dependent post-translational regulation of the T6SS is tailored to fit the needs of different bacterial

  15. In silico dissection of Type VII Secretion System components across ...

    Indian Academy of Sciences (India)

    2016-02-12

    Feb 12, 2016 ... Bio-Sciences R&D Division, TCS Innovation Labs, Tata Research Development & Design Centre, ... Type VII Secretion System (T7SS) is one of the factors involved in virulence of ... Such wide distribution of T7SS and.

  16. Identification of genes encoding the type IX secretion system and secreted proteins in Flavobacterium columnare IA-S-4

    Science.gov (United States)

    Flavobacterium columnare, a member of the phylum Bacteroidetes, causes columnaris disease in wild and aquaculture-reared freshwater fish. The mechanisms responsible for columnaris disease are not known. Many members of the phylum Bacteroidetes use type IX secretion systems (T9SSs) to secrete enzymes...

  17. Por secretion system-dependent secretion and glycosylation of Porphyromonas gingivalis hemin-binding protein 35.

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    Mikio Shoji

    Full Text Available The anaerobic Gram-negative bacterium Porphyromonas gingivalis is a major pathogen in severe forms of periodontal disease and refractory periapical perodontitis. We have recently found that P. gingivalis has a novel secretion system named the Por secretion system (PorSS, which is responsible for secretion of major extracellular proteinases, Arg-gingipains (Rgps and Lys-gingipain. These proteinases contain conserved C-terminal domains (CTDs in their C-termini. Hemin-binding protein 35 (HBP35, which is one of the outer membrane proteins of P. gingivalis and contributes to its haem utilization, also contains a CTD, suggesting that HBP35 is translocated to the cell surface via the PorSS. In this study, immunoblot analysis of P. gingivalis mutants deficient in the PorSS or in the biosynthesis of anionic polysaccharide-lipopolysaccharide (A-LPS revealed that HBP35 is translocated to the cell surface via the PorSS and is glycosylated with A-LPS. From deletion analysis with a GFP-CTD[HBP35] green fluorescent protein fusion, the C-terminal 22 amino acid residues of CTD[HBP35] were found to be required for cell surface translocation and glycosylation. The GFP-CTD fusion study also revealed that the CTDs of CPG70, peptidylarginine deiminase, P27 and RgpB play roles in PorSS-dependent translocation and glycosylation. However, CTD-region peptides were not found in samples of glycosylated HBP35 protein by peptide map fingerprinting analysis, and antibodies against CTD-regions peptides did not react with glycosylated HBP35 protein. These results suggest both that the CTD region functions as a recognition signal for the PorSS and that glycosylation of CTD proteins occurs after removal of the CTD region. Rabbits were used for making antisera against bacterial proteins in this study.

  18. Small-Molecule Inhibitors of the Type III Secretion System

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    Lingling Gu

    2015-09-01

    Full Text Available Drug-resistant pathogens have presented increasing challenges to the discovery and development of new antibacterial agents. The type III secretion system (T3SS, existing in bacterial chromosomes or plasmids, is one of the most complicated protein secretion systems. T3SSs of animal and plant pathogens possess many highly conserved main structural components comprised of about 20 proteins. Many Gram-negative bacteria carry T3SS as a major virulence determinant, and using the T3SS, the bacteria secrete and inject effector proteins into target host cells, triggering disease symptoms. Therefore, T3SS has emerged as an attractive target for antimicrobial therapeutics. In recent years, many T3SS-targeting small-molecule inhibitors have been discovered; these inhibitors prevent the bacteria from injecting effector proteins and from causing pathophysiology in host cells. Targeting the virulence of Gram-negative pathogens, rather than their survival, is an innovative and promising approach that may greatly reduce selection pressures on pathogens to develop drug-resistant mutations. This article summarizes recent progress in the search for promising small-molecule T3SS inhibitors that target the secretion and translocation of bacterial effector proteins.

  19. A novel secret image sharing scheme based on chaotic system

    Science.gov (United States)

    Li, Li; Abd El-Latif, Ahmed A.; Wang, Chuanjun; Li, Qiong; Niu, Xiamu

    2012-04-01

    In this paper, we propose a new secret image sharing scheme based on chaotic system and Shamir's method. The new scheme protects the shadow images with confidentiality and loss-tolerance simultaneously. In the new scheme, we generate the key sequence based on chaotic system and then encrypt the original image during the sharing phase. Experimental results and analysis of the proposed scheme demonstrate a better performance than other schemes and confirm a high probability to resist brute force attack.

  20. The type III protein secretion system contributes to Xanthomonas citri subsp. citri biofilm formation

    KAUST Repository

    Zimaro, Tamara; Thomas, Ludivine; Marondedze, Claudius; Sgro, Germá n G; Garofalo, Cecilia G; Ficarra, Florencia A; Gehring, Christoph A; Ottado, Jorgelina; Gottig, Natalia

    2014-01-01

    Background: Several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a Type III protein secretion system (T3SS). The role of T3SS in bacterial pathogenesis is well established but whether this system

  1. Burkholderia cenocepacia type VI secretion system mediates escape of type II secreted proteins into the cytoplasm of infected macrophages.

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    Roberto Rosales-Reyes

    Full Text Available Burkholderia cenocepacia is an opportunistic pathogen that survives intracellularly in macrophages and causes serious respiratory infections in patients with cystic fibrosis. We have previously shown that bacterial survival occurs in bacteria-containing membrane vacuoles (BcCVs resembling arrested autophagosomes. Intracellular bacteria stimulate IL-1β secretion in a caspase-1-dependent manner and induce dramatic changes to the actin cytoskeleton and the assembly of the NADPH oxidase complex onto the BcCV membrane. A Type 6 secretion system (T6SS is required for these phenotypes but surprisingly it is not required for the maturation arrest of the BcCV. Here, we show that macrophages infected with B. cenocepacia employ the NLRP3 inflammasome to induce IL-1β secretion and pyroptosis. Moreover, IL-1β secretion by B. cenocepacia-infected macrophages is suppressed in deletion mutants unable to produce functional Type VI, Type IV, and Type 2 secretion systems (SS. We provide evidence that the T6SS mediates the disruption of the BcCV membrane, which allows the escape of proteins secreted by the T2SS into the macrophage cytoplasm. This was demonstrated by the activity of fusion derivatives of the T2SS-secreted metalloproteases ZmpA and ZmpB with adenylcyclase. Supporting this notion, ZmpA and ZmpB are required for efficient IL-1β secretion in a T6SS dependent manner. ZmpA and ZmpB are also required for the maturation arrest of the BcCVs and bacterial intra-macrophage survival in a T6SS-independent fashion. Our results uncover a novel mechanism for inflammasome activation that involves cooperation between two bacterial secretory pathways, and an unanticipated role for T2SS-secreted proteins in intracellular bacterial survival.

  2. Identification of Anaplasma marginale type IV secretion system effector proteins.

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    Svetlana Lockwood

    Full Text Available Anaplasma marginale, an obligate intracellular alphaproteobacterium in the order Rickettsiales, is a tick-borne pathogen and the leading cause of anaplasmosis in cattle worldwide. Complete genome sequencing of A. marginale revealed that it has a type IV secretion system (T4SS. The T4SS is one of seven known types of secretion systems utilized by bacteria, with the type III and IV secretion systems particularly prevalent among pathogenic Gram-negative bacteria. The T4SS is predicted to play an important role in the invasion and pathogenesis of A. marginale by translocating effector proteins across its membrane into eukaryotic target cells. However, T4SS effector proteins have not been identified and tested in the laboratory until now.By combining computational methods with phylogenetic analysis and sequence identity searches, we identified a subset of potential T4SS effectors in A. marginale strain St. Maries and chose six for laboratory testing. Four (AM185, AM470, AM705 [AnkA], and AM1141 of these six proteins were translocated in a T4SS-dependent manner using Legionella pneumophila as a reporter system.The algorithm employed to find T4SS effector proteins in A. marginale identified four such proteins that were verified by laboratory testing. L. pneumophila was shown to work as a model system for A. marginale and thus can be used as a screening tool for A. marginale effector proteins. The first T4SS effector proteins for A. marginale have been identified in this work.

  3. ''C-ring'' stress corrosion cracking scoping experiment for Zircaloy spent fuel cladding

    International Nuclear Information System (INIS)

    Smith, H.D.

    1986-03-01

    This document describes the purpose and execution of the stress corrosion cracking scoping experiment using ''C-ring'' cladding specimens. The design and operation of the ''C-ring'' stressing apparatus is described and discussed. The experimental procedures and post-experiment sample evaluation are described

  4. DLP system and the secret of personal correspondence

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    Mavrinskaya T.V.

    2017-04-01

    Full Text Available according to the authors, every day a number of threats to information security increases, and this requires an increase in resources (systems of information protection of organizations and enterprises. There are many information security tools with different functionality, but the main mean of preventing information leakage is the Date Loss Prevention (DLP system. If you need to establish control over the leak of confidential information there appear a number of questions of conformity of decisions with the legislation and regulations. This article describes the issue of compliance functionality of a DLP system the provisions and requirements of the legislation in the sphere of protection of family and personal secrets, as well as compliance with the Constitutional right of citizens to privacy of correspondence.

  5. Two-partner secretion systems of Neisseria meningitidis associated with invasive clonal complexes

    NARCIS (Netherlands)

    van Ulsen, Peter; Rutten, Lucy; Feller, Moniek; Tommassen, Jan; van der Ende, Arie

    2008-01-01

    The two-partner secretion (TPS) pathway is widespread among gram-negative bacteria and facilitates the secretion of very large and often virulence-related proteins. TPS systems consist of a secreted TpsA protein and a TpsB protein involved in TpsA transport across the outer membrane. Sequenced

  6. T3SEdb: data warehousing of virulence effectors secreted by the bacterial Type III Secretion System.

    Science.gov (United States)

    Tay, Daniel Ming Ming; Govindarajan, Kunde Ramamoorthy; Khan, Asif M; Ong, Terenze Yao Rui; Samad, Hanif M; Soh, Wei Wei; Tong, Minyan; Zhang, Fan; Tan, Tin Wee

    2010-10-15

    Effectors of Type III Secretion System (T3SS) play a pivotal role in establishing and maintaining pathogenicity in the host and therefore the identification of these effectors is important in understanding virulence. However, the effectors display high level of sequence diversity, therefore making the identification a difficult process. There is a need to collate and annotate existing effector sequences in public databases to enable systematic analyses of these sequences for development of models for screening and selection of putative novel effectors from bacterial genomes that can be validated by a smaller number of key experiments. Herein, we present T3SEdb http://effectors.bic.nus.edu.sg/T3SEdb, a specialized database of annotated T3SS effector (T3SE) sequences containing 1089 records from 46 bacterial species compiled from the literature and public protein databases. Procedures have been defined for i) comprehensive annotation of experimental status of effectors, ii) submission and curation review of records by users of the database, and iii) the regular update of T3SEdb existing and new records. Keyword fielded and sequence searches (BLAST, regular expression) are supported for both experimentally verified and hypothetical T3SEs. More than 171 clusters of T3SEs were detected based on sequence identity comparisons (intra-cluster difference up to ~60%). Owing to this high level of sequence diversity of T3SEs, the T3SEdb provides a large number of experimentally known effector sequences with wide species representation for creation of effector predictors. We created a reliable effector prediction tool, integrated into the database, to demonstrate the application of the database for such endeavours. T3SEdb is the first specialised database reported for T3SS effectors, enriched with manual annotations that facilitated systematic construction of a reliable prediction model for identification of novel effectors. The T3SEdb represents a platform for inclusion of

  7. T3SEdb: data warehousing of virulence effectors secreted by the bacterial Type III Secretion System

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    Tong Minyan

    2010-10-01

    Full Text Available Abstract Background Effectors of Type III Secretion System (T3SS play a pivotal role in establishing and maintaining pathogenicity in the host and therefore the identification of these effectors is important in understanding virulence. However, the effectors display high level of sequence diversity, therefore making the identification a difficult process. There is a need to collate and annotate existing effector sequences in public databases to enable systematic analyses of these sequences for development of models for screening and selection of putative novel effectors from bacterial genomes that can be validated by a smaller number of key experiments. Results Herein, we present T3SEdb http://effectors.bic.nus.edu.sg/T3SEdb, a specialized database of annotated T3SS effector (T3SE sequences containing 1089 records from 46 bacterial species compiled from the literature and public protein databases. Procedures have been defined for i comprehensive annotation of experimental status of effectors, ii submission and curation review of records by users of the database, and iii the regular update of T3SEdb existing and new records. Keyword fielded and sequence searches (BLAST, regular expression are supported for both experimentally verified and hypothetical T3SEs. More than 171 clusters of T3SEs were detected based on sequence identity comparisons (intra-cluster difference up to ~60%. Owing to this high level of sequence diversity of T3SEs, the T3SEdb provides a large number of experimentally known effector sequences with wide species representation for creation of effector predictors. We created a reliable effector prediction tool, integrated into the database, to demonstrate the application of the database for such endeavours. Conclusions T3SEdb is the first specialised database reported for T3SS effectors, enriched with manual annotations that facilitated systematic construction of a reliable prediction model for identification of novel effectors

  8. Yersinia Type III Secretion System Master Regulator LcrF

    Science.gov (United States)

    Schwiesow, Leah; Lam, Hanh

    2015-01-01

    Many Gram-negative pathogens express a type III secretion (T3SS) system to enable growth and survival within a host. The three human-pathogenic Yersinia species, Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica, encode the Ysc T3SS, whose expression is controlled by an AraC-like master regulator called LcrF. In this review, we discuss LcrF structure and function as well as the environmental cues and pathways known to regulate LcrF expression. Similarities and differences in binding motifs and modes of action between LcrF and the Pseudomonas aeruginosa homolog ExsA are summarized. In addition, we present a new bioinformatics analysis that identifies putative LcrF binding sites within Yersinia target gene promoters. PMID:26644429

  9. Heterologous protein secretion in Lactococcus lactis: a novel antigen delivery system

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    Langella P.

    1999-01-01

    Full Text Available Lactic acid bacteria (LAB are Gram-positive bacteria and are generally regarded as safe (GRAS organisms. Therefore, LAB could be used for heterologous protein secretion and they are good potential candidates as antigen delivery vehicles. To develop such live vaccines, a better control of protein secretion is required. We developed an efficient secretion system in the model LAB, Lactococcus lactis. Staphylococcal nuclease (Nuc was used as the reporter protein. We first observed that the quantity of secreted Nuc correlated with the copy number of the cloning vector. The nuc gene was cloned on a high-copy number cloning vector and no perturbation of the metabolism of the secreting strain was observed. Replacement of nuc native promoter by a strong lactococcal one led to a significant increase of nuc expression. Secretion efficiency (SE of Nuc in L. lactis was low, i.e., only 60% of the synthesized Nuc was secreted. Insertion of a synthetic propeptide between the signal peptide and the mature moiety of Nuc increased the SE of Nuc. On the basis of these results, we developed a secretion system and we applied it to the construction of an L. lactis strain which secretes a bovine coronavirus (BCV epitope-protein fusion (BCV-Nuc. BCV-Nuc was recognized by both anti-BCV and anti-Nuc antibodies. Secretion of this antigenic fusion is the first step towards the development of a novel antigen delivery system based on LAB-secreting strains.

  10. A novel genetic system for recombinant protein secretion in the Antarctic Pseudoalteromonas haloplanktis TAC125

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    Marino Gennaro

    2006-12-01

    Full Text Available Abstract Background The final aim of recombinant protein production is both to have a high specific production rate and a high product quality. It was already shown that using cold-adapted bacteria as host vectors, some "intractable" proteins can be efficiently produced at temperature as low as 4°C. Results A novel genetic system for the production and secretion of recombinant proteins in the Antarctic Gram-negative bacterium Pseudoalteromonas haloplanktis TAC125 was set up. This system aims at combining the low temperature recombinant product production with the advantages of extra-cellular protein targeting. The psychrophilic α-amylase from Pseudoalteromonas haloplanktis TAB23 was used as secretion carrier. Three chimerical proteins were produced by fusing intra-cellular proteins to C-terminus of the psychrophilic α-amylase and their secretion was analysed. Data reported in this paper demonstrate that all tested chimeras were translocated with a secretion yield always higher than 80%. Conclusion Data presented here demonstrate that the "cold" gene-expression system is efficient since the secretion yield of tested chimeras is always above 80%. These secretion performances place the α-amylase derived secretion system amongst the best heterologous secretion systems in Gram-negative bacteria reported so far. As for the quality of the secreted passenger proteins, data presented suggest that the system also allows the correct disulphide bond formation of chimera components, secreting a fully active passenger.

  11. Development of stress relaxation measurement by a small size C-ring specimen method

    International Nuclear Information System (INIS)

    Shimanuki, Shizuka; Nakata, Kiyotomo; Kasahara, Shigeki; Kuniya, Jiro

    2002-01-01

    A stress relaxation measurement method has been developed by using C-ring specimens, and a specimen size effect has been evaluated taking radiation-induced stress relaxation into consideration. C-ring specimens were stressed by forcing a wedge in the gap. Giving an appropriate eccentric configuration in the half of the ring opposite the gap, the stress gradient along the circumference was eliminated in the section and the stress level could be varied by changing the gap spacing. The validity of the C-ring test method was confirmed by thermally stress relaxation experiments at annealing temperatures from 300 to 600degC for 1 min to 200 h in carbon steel: considerable stress relaxation could be measured for all levels of applied stress even at relatively low annealing temperatures. The relaxation results obtained from the C-ring test were in good agreement with those from a uniaxial tensile stress relaxation test. The smaller C-ring specimen with about 40 mm diameter, which is required for radiation-induced stress relaxation test, also showed adequate accuracy on stress relaxation at 600 to 830degC in stainless steel, compared with the large size C-ring specimen test. (author)

  12. Type-IVC Secretion System: A Novel Subclass of Type IV Secretion System (T4SS) Common Existing in Gram-Positive Genus Streptococcus

    Science.gov (United States)

    Chen, Chen; Gao, George F.

    2012-01-01

    A growing number of pathogens are being found to possess specialized secretion systems which they use in various ways to subvert host defenses. Type IV secretion system (T4SS) is one of versatile secretion systems essential for the virulence and even survival of some bacteria species, and they enable the secretion of protein and DNA substrates across the cell envelope. T4SS was once believed to be present only in Gram-negative bacteria. In this study, we present evidence of a new subclass of T4SS, Type-IVC secretion system and indicate its common existence in the Gram-positive bacterial genus Streptococcus. We further identified that VirB1, VirB4, VirB6 and VirD4 are the minimal key components of this system. Using genome comparisons and evolutionary relationship analysis, we proposed that Type-IVC secretion system is movable via transposon factors and mediates the conjugative transfer of DNA, enhances bacterial pathogenicity, and could cause large-scale outbreaks of infections in humans. PMID:23056296

  13. A Phytase-Based Reporter System for Identification of Functional Secretion Signals in Bifidobacteria.

    Directory of Open Access Journals (Sweden)

    Annika Osswald

    Full Text Available Health-promoting effects have been attributed to a number of Bifidobacterium sp. strains. These effects as well as the ability to colonise the host depend on secreted proteins. Moreover, rational design of protein secretion systems bears the potential for the generation of novel probiotic bifidobacteria with improved health-promoting or therapeutic properties. To date, there is only very limited data on secretion signals of bifidobacteria available. Using in silico analysis, we demonstrate that all bifidobacteria encode the major components of Sec-dependent secretion machineries but only B. longum strains harbour Tat protein translocation systems. A reporter plasmid for secretion signals in bifidobacteria was established by fusing the coding sequence of the signal peptide of a sialidase of Bifidobacterium bifidum S17 to the phytase gene appA of E. coli. The recombinant strain showed increased phytase activity in spent culture supernatants and reduced phytase levels in crude extracts compared to the control indicating efficient phytase secretion. The reporter plasmid was used to screen seven predicted signal peptides in B. bifidum S17 and B. longum E18. The tested signal peptides differed substantially in their efficacy to mediate protein secretion in different host strains. An efficient signal peptide was used for expression and secretion of a therapeutically relevant protein in B. bifidum S17. Expression of a secreted cytosine deaminase led to a 100-fold reduced sensitivity of B. bifidum S17 to 5-fluorocytosine compared to the non-secreted cytosine deaminase suggesting efficient conversion of 5-fluorocytosine to the cytotoxic cancer drug 5-fluorouracil by cytosine deaminase occurred outside the bacterial cell. Selection of appropriate signal peptides for defined protein secretion might improve therapeutic efficacy as well as probiotic properties of bifidobacteria.

  14. A Phytase-Based Reporter System for Identification of Functional Secretion Signals in Bifidobacteria

    Science.gov (United States)

    Osswald, Annika; Westermann, Christina; Sun, Zhongke; Riedel, Christian U.

    2015-01-01

    Health-promoting effects have been attributed to a number of Bifidobacterium sp. strains. These effects as well as the ability to colonise the host depend on secreted proteins. Moreover, rational design of protein secretion systems bears the potential for the generation of novel probiotic bifidobacteria with improved health-promoting or therapeutic properties. To date, there is only very limited data on secretion signals of bifidobacteria available. Using in silico analysis, we demonstrate that all bifidobacteria encode the major components of Sec-dependent secretion machineries but only B. longum strains harbour Tat protein translocation systems. A reporter plasmid for secretion signals in bifidobacteria was established by fusing the coding sequence of the signal peptide of a sialidase of Bifidobacterium bifidum S17 to the phytase gene appA of E. coli. The recombinant strain showed increased phytase activity in spent culture supernatants and reduced phytase levels in crude extracts compared to the control indicating efficient phytase secretion. The reporter plasmid was used to screen seven predicted signal peptides in B. bifidum S17 and B. longum E18. The tested signal peptides differed substantially in their efficacy to mediate protein secretion in different host strains. An efficient signal peptide was used for expression and secretion of a therapeutically relevant protein in B. bifidum S17. Expression of a secreted cytosine deaminase led to a 100-fold reduced sensitivity of B. bifidum S17 to 5-fluorocytosine compared to the non-secreted cytosine deaminase suggesting efficient conversion of 5-fluorocytosine to the cytotoxic cancer drug 5-fluorouracil by cytosine deaminase occurred outside the bacterial cell. Selection of appropriate signal peptides for defined protein secretion might improve therapeutic efficacy as well as probiotic properties of bifidobacteria. PMID:26086721

  15. The c-Ring of the F1FO-ATP Synthase: Facts and Perspectives.

    Science.gov (United States)

    Nesci, Salvatore; Trombetti, Fabiana; Ventrella, Vittoria; Pagliarani, Alessandra

    2016-04-01

    The F1FO-ATP synthase is the only enzyme in nature endowed with bi-functional catalytic mechanism of synthesis and hydrolysis of ATP. The enzyme functions, not only confined to energy transduction, are tied to three intrinsic features of the annular arrangement of c subunits which constitutes the so-called c-ring, the core of the membrane-embedded FO domain: (i) the c-ring constitution is linked to the number of ions (H(+) or Na(+)) channeled across the membrane during the dissipation of the transmembrane electrochemical gradient, which in turn determines the species-specific bioenergetic cost of ATP, the "molecular currency unit" of energy transfer in all living beings; (ii) the c-ring is increasingly involved in the mitochondrial permeability transition, an event linked to cell death and to most mitochondrial dysfunctions; (iii) the c subunit species-specific amino acid sequence and susceptibility to post-translational modifications can address antibacterial drug design according to the model of enzyme inhibitors which target the c subunits. Therefore, the simple c-ring structure not only allows the F1FO-ATP synthase to perform the two opposite tasks of molecular machine of cell life and death, but it also amplifies the enzyme's potential role as a drug target.

  16. Quantification of Applied Stresses of C-Ring Specimens for Stress Corrosion Cracking Tests

    International Nuclear Information System (INIS)

    Kim, Woo Gon; Kim, Sun Jae; Rhee, Chang Kyu; Kuk, Il Hiun; Choi, Jong Ho

    1997-01-01

    For comparing their resistances for stress-corrosion cracking(SCC) in the K600-MA, K690-MA, and K600-TT tubes, C-ring specimens were fabricated with the various thermal-treatments to control the distributions of the precipitates like Cr-carbides. The bending stresses were analyzed to determine the amounts to make the stress quantitatively to all the C-ring samples, and then the stresses were calculated with the relation to the outer diameter(O.D) deflection(δ) of the C-rings. To measure accurately the bending strains of the C-ring specimens, the strain gauges were used and the compression test was also carried out. In the elastic region, the stresses in both the transverse and the circumferential directions were different with the locations of the strain gauges as attached at α= 30 .deg., 45 .deg., and 90 .deg. to the principal stress direction, but those in the longitudinal direction were independent of their attached locations. Calculated stresses from the strains obtained using the strain gauges were well agreed with the theoretical. In the plastic region over δ=1.0mm, the stresses for the TT tubes showed lower values of about 400MPa than those for the MA tubes. However, the stresses among the TT tubes showed almost the similar values in this region. Therefore, the states of the stresses applied to the C-ring specimens would be different with the material conditions, i.e, the chemical compositions, the thermal treatments such as MA and TT

  17. Shigella IpaD has a dual role: signal transduction from the type III secretion system needle tip and intracellular secretion regulation.

    Science.gov (United States)

    Roehrich, A Dorothea; Guillossou, Enora; Blocker, Ariel J; Martinez-Argudo, Isabel

    2013-02-01

    Type III secretion systems (T3SSs) are protein injection devices essential for the interaction of many Gram-negative bacteria with eukaryotic cells. While Shigella assembles its T3SS when the environmental conditions are appropriate for invasion, secretion is only activated after physical contact with a host cell. First, the translocators are secreted to form a pore in the host cell membrane, followed by effectors which manipulate the host cell. Secretion activation is tightly controlled by conserved T3SS components: the needle tip proteins IpaD and IpaB, the needle itself and the intracellular gatekeeper protein MxiC. To further characterize the role of IpaD during activation, we combined random mutagenesis with a genetic screen to identify ipaD mutant strains unable to respond to host cell contact. Class II mutants have an overall defect in secretion induction. They map to IpaD's C-terminal helix and likely affect activation signal generation or transmission. The Class I mutant secretes translocators prematurely and is specifically defective in IpaD secretion upon activation. A phenotypically equivalent mutant was found in mxiC. We show that IpaD and MxiC act in the same intracellular pathway. In summary, we demonstrate that IpaD has a dual role and acts at two distinct locations during secretion activation. © 2013 Blackwell Publishing Ltd.

  18. Roles of silkworm endoplasmic reticulum chaperones in the secretion of recombinant proteins expressed by baculovirus system.

    Science.gov (United States)

    Imai, Saki; Kusakabe, Takahiro; Xu, Jian; Li, Zhiqing; Shirai, Shintaro; Mon, Hiroaki; Morokuma, Daisuke; Lee, Jae Man

    2015-11-01

    Baculovirus expression vector system (BEVS) is widely used for production of recombinant eukaryotic proteins in insect larvae or cultured cells. BEVS has advantages over bacterial expression system in producing post-translationally modified secreted proteins. However, for some unknown reason, it is very difficult for insects to secrete sufficiently for certain proteins of interest. To understand the reasons why insect cells fail to secrete some kinds of recombinant proteins, we here employed three mammalian proteins as targets, EPO, HGF, and Wnt3A, with different secretion levels in BEVS and investigated their mRNA transcriptions from the viral genome, subcellular localizations, and interactions with silkworm ER chaperones. Moreover, we observed that no significantly influence on the secretion amounts of all three proteins when depleting or overexpressing most endogenous ER chaperone genes in cultured silkworm cells. However, among all detected ER chaperones, the depletion of BiP severely decreased the recombinant protein secretion in BEVS, indicating the possible central role of Bip in silkworm secretion pathway.

  19. Type IV Secretion System of Brucella spp. and its Effectors

    Directory of Open Access Journals (Sweden)

    Yuehua eKe

    2015-10-01

    Full Text Available Brucella spp. cause brucellosis in domestic and wild animals. They are intracellular bacterial pathogens and used as model organisms to study intracellular bacterial infections. Brucella VirB T4SS is a key virulence factor that plays important roles in mediating intracellular survival and manipulating host immune response to infection. In this review, we will discuss roles of Brucella VirB T4SS and in more detail of all 15 identified effectors, which may be crucial for Brucella pathogenesis. VirB T4SS regulates the inflammation response and manipulates vesicle trafficking inside host cells, suggesting that it plays crucial roles in the inhibition of the host immune response and intracellular survival during infection. So, we listed some key molecular events in the intracellular life cycle of Brucella potentially targeted by the VirB T4SS effectors. Elucidating functions of the effectors secreted will be crucial to clarifying mechanism of T4SS during infection. Studying the effectors secreted by Brucella spp. might provide insights into the mechanisms by which the bacteria hijack the host signaling pathways, which help us to develop better vaccines and therapies against brucellosis.

  20. Proteomes of the barley aleurone layer: A model system for plant signalling and protein secretion

    DEFF Research Database (Denmark)

    Finnie, Christine; Andersen, Birgit; Shahpiri, Azar

    2011-01-01

    molecules in an isolated system. These properties have led to its use as a model system for the study of plant signalling and germination. More recently, proteome analysis of the aleurone layer has provided new insight into this unique tissue including identification of plasma membrane proteins and targeted...... analysis of germination-related changes and the thioredoxin system. Here, analysis of intracellular and secreted proteomes reveals features of the aleurone layer system that makes it promising for investigations of plant protein secretion mechanisms....... to gibberellic acid produced by the embryo, the aleurone layer synthesises hydrolases that are secreted to the endosperm for the degradation of storage products. The barley aleurone layer can be separated from the other seed tissues and maintained in culture, allowing the study of the effect of added signalling...

  1. Type IV secretion system of Brucella spp. and its effectors.

    Science.gov (United States)

    Ke, Yuehua; Wang, Yufei; Li, Wengfeng; Chen, Zeliang

    2015-01-01

    Brucella spp. are intracellular bacterial pathogens that cause infection in domestic and wild animals. They are often used as model organisms to study intracellular bacterial infections. Brucella VirB T4SS is a key virulence factor that plays important roles in mediating intracellular survival and manipulating host immune response to infection. In this review, we discuss the roles of Brucella VirB T4SS and 15 effectors that are proposed to be crucial for Brucella pathogenesis. VirB T4SS regulates the inflammation response and manipulates vesicle trafficking inside host cells. VirB T4SS also plays crucial roles in the inhibition of the host immune response and intracellular survival during infection. Here, we list the key molecular events in the intracellular life cycle of Brucella that are potentially targeted by the VirB T4SS effectors. Elucidating the functions of these effectors will help clarify the molecular role of T4SS during infection. Furthermore, studying the effectors secreted by Brucella spp. might provide insights into the mechanisms used by the bacteria to hijack the host signaling pathways and aid in the development of better vaccines and therapies against brucellosis.

  2. A protein secretion system linked to bacteroidete gliding motility and pathogenesis

    Science.gov (United States)

    Sato, Keiko; Naito, Mariko; Yukitake, Hideharu; Hirakawa, Hideki; Shoji, Mikio; McBride, Mark J.; Rhodes, Ryan G.; Nakayama, Koji

    2009-01-01

    Porphyromonas gingivalis secretes strong proteases called gingipains that are implicated in periodontal pathogenesis. Protein secretion systems common to other Gram-negative bacteria are lacking in P. gingivalis, but several proteins, including PorT, have been linked to gingipain secretion. Comparative genome analysis and genetic experiments revealed 11 additional proteins involved in gingipain secretion. Six of these (PorK, PorL, PorM, PorN, PorW, and Sov) were similar in sequence to Flavobacterium johnsoniae gliding motility proteins, and two others (PorX and PorY) were putative two-component system regulatory proteins. Real-time RT-PCR analysis revealed that porK, porL, porM, porN, porP, porT, and sov were down-regulated in P. gingivalis porX and porY mutants. Disruption of the F. johnsoniae porT ortholog resulted in defects in motility, chitinase secretion, and translocation of a gliding motility protein, SprB adhesin, to the cell surface, providing a link between a unique protein translocation system and a motility apparatus in members of the Bacteroidetes phylum. PMID:19966289

  3. Identification and characterization of a type III secretion-associated chaperone in the type III secretion system 1 of Vibrio parahaemolyticus.

    Science.gov (United States)

    Akeda, Yukihiro; Okayama, Kanna; Kimura, Tomomi; Dryselius, Rikard; Kodama, Toshio; Oishi, Kazunori; Iida, Tetsuya; Honda, Takeshi

    2009-07-01

    Vibrio parahaemolyticus causes human gastroenteritis. Genomic sequencing of this organism has revealed that it has two sets of type III secretion systems, T3SS1 and T3SS2, both of which are important for its pathogenicity. However, the mechanism of protein secretion via T3SSs is unknown. A characteristic of many effectors is that they require specific chaperones for efficient delivery via T3SSs; however, no chaperone has been experimentally identified in the T3SSs of V. parahaemolyticus. In this study, we identified candidate T3SS1-associated chaperones from genomic sequence data and examined their roles in effector secretion/translocation and binding to their cognate substrates. From these experiments, we concluded that there is a T3S-associated chaperone, VecA, for a cytotoxic T3SS1-dependent effector, VepA. Further analysis using pulldown and secretion assays characterized the chaperone-binding domain encompassing the first 30-100 amino acids and an amino terminal secretion signal encompassing the first 5-20 amino acids on VepA. These findings will provide a strategy to clarify how the T3SS1 of V. parahaemolyticus secretes its specific effectors.

  4. LcrQ and SycH function together at the Ysc type III secretion system in Yersinia pestis to impose a hierarchy of secretion.

    Science.gov (United States)

    Wulff-Strobel, Christine R; Williams, Andrew W; Straley, Susan C

    2002-01-01

    LcrQ is a regulatory protein unique to Yersinia. Previous study in Yersinia pseudotuberculosis and Yersinia enterocolitica prompted the model in which LcrQ negatively regulates the expression of a set of virulence proteins called Yops, and its secretion upon activation of the Yop secretion (Ysc) type III secretion system permits full induction of Yops expression. In this study, we tested the hypothesis that LcrQ's effects on Yops expression might be indirect. Excess LcrQ was found to exert an inhibitory effect specifically at the level of Yops secretion, independent of production, and a normal inner Ysc gate protein LcrG was required for this activity. However, overexpression of LcrQ did not prevent YopH secretion, suggesting that LcrQ's effects at the Ysc discriminate among the Yops. We tested this idea by determining the effects of deletion or overexpression of LcrQ, YopH and their common chaperone SycH on early Yop secretion through the Ysc. Together, our findings indicated that LcrQ is not a negative regulator directly, but it acts in partnership with SycH at the Ysc gate to control the entry of a set of Ysc secretion substrates. A hierarchy of YopH secretion before YopE appears to be imposed by SycH in conjunction with both LcrQ and YopH. LcrQ and SycH in addition influenced the deployment of LcrV, a component of the Yops delivery mechanism. Accordingly, LcrQ appears to be a central player in determining the substrate specificity of the Ysc.

  5. Measurement of surface-induced microplasticity in Alloy 600 C-rings

    International Nuclear Information System (INIS)

    Lo, C.F.; Kamide, H.; Mayo, W.E.; Weissmann, S.

    1990-03-01

    The level of microplasticity in Alloy 600 specimens used for accelerated SCC tests was measured with the aid of a novel x-ray rocking curve technique developed at Rutgers University. With this tool, it was possible to measure quantitatively the strain level at any point along the circumference of a C-ring. Combined with selective etching, the method was used to obtain a depth profile of the strain. A detailed study of the deformation state in C-rings was performed with a particular emphasis on how material parameters influence localization of the strain. These studies included the role of grain boundary carbides, grain size and mill anneal temperatures. The studies led to the development of a numerical model for calculation of the strain distribution along a C-ring which is superior to that currently in use. An additional result of these studies was a simple indirect method that can be used to determine the amount of grain boundary carbides present in tubes of Alloy 600. The final phase of this project was to measure the strain relaxation kinetics in this alloy. From this work, the activation energy for relaxation and the atomistic process responsible were identified. Based on this work, calculations were performed to indicate the degree of relaxation that can be expected during normal steam generator operation and accelerated SCC testing. These calculations suggest that relaxation may be significant in the temperature range of 280--360 degree C which is typical for such tests and highlights the fact that during these tests significant changes in the microstructure that can be detected by x-rays are taking place. These results will provide a more accurate basis for extrapolating tests to actual steam generator corrosion experience. 6 figs., 2 tabs

  6. Genome-scale analysis of the high-efficient protein secretion system of Aspergillus oryzae

    DEFF Research Database (Denmark)

    Liu, Lifang; Feizi, Amir; Osterlund, Tobias

    2014-01-01

    related fungal species such as Aspergillus nidulans and Aspergillus niger. To evaluate the defined component list, we performed transcriptome analysis on three a-amylase over-producing strains with varying levels of secretion capacities. Specifically, secretory components involved in the ER......Background: The koji mold, Aspergillus oryzae is widely used for the production of industrial enzymes due to its particularly high protein secretion capacity and ability to perform post-translational modifications. However, systemic analysis of its secretion system is lacking, generally due...... to the poorly annotated proteome. Results: Here we defined a functional protein secretory component list of A. oryzae using a previously reported secretory model of S. cerevisiae as scaffold. Additional secretory components were obtained by blast search with the functional components reported in other closely...

  7. Molecular model of a type III secretion system needle: Implications for host-cell sensing.

    Science.gov (United States)

    Deane, Janet E; Roversi, Pietro; Cordes, Frank S; Johnson, Steven; Kenjale, Roma; Daniell, Sarah; Booy, Frank; Picking, William D; Picking, Wendy L; Blocker, Ariel J; Lea, Susan M

    2006-08-15

    Type III secretion systems are essential virulence determinants for many Gram-negative bacterial pathogens. The type III secretion system consists of cytoplasmic, transmembrane, and extracellular domains. The extracellular domain is a hollow needle protruding above the bacterial surface and is held within a basal body that traverses both bacterial membranes. Effector proteins are translocated, via this external needle, directly into host cells, where they subvert normal cell functions to aid infection. Physical contact with host cells initiates secretion and leads to formation of a pore, thought to be contiguous with the needle channel, in the host-cell membrane. Here, we report the crystal structure of the Shigella flexneri needle subunit MxiH and a complete model for the needle assembly built into our three-dimensional EM reconstruction. The model, combined with mutagenesis data, reveals that signaling of host-cell contact is relayed through the needle via intersubunit contacts and suggests a mode of binding for a tip complex.

  8. A translocator-specific export signal establishes the translocator-effector secretion hierarchy that is important for type III secretion system function

    Science.gov (United States)

    Tomalka, Amanda G.; Stopford, Charles M.; Lee, Pei-Chung; Rietsch, Arne

    2012-01-01

    Summary Type III secretion systems are used by many Gram-negative pathogens to directly deliver effector proteins into the cytoplasm of host cells. To accomplish this, bacteria secrete translocator proteins that form a pore in the host-cell membrane through which the effector proteins are then introduced into the host cell. Evidence from multiple systems indicates that the pore-forming translocator proteins are exported before effectors, but how this secretion hierarchy is established is unclear. Here we used the P. aeruginosa translocator protein PopD as a model to identify its export signals. The amino-terminal secretion signal and chaperone, PcrH, are required for export under all conditions. Two novel signals in PopD, one proximal to the chaperone-binding site and one at the very C-terminus of the protein, are required for export of PopD before effector proteins. These novel export signals establish the translocator-effector secretion hierarchy, which in turn, is critical for the delivery of effectors into host cells. PMID:23121689

  9. Structural and Functional Insights into the Pilotin-Secretin Complex of the Type II Secretion System

    OpenAIRE

    Gu, Shuang; Rehman, Saima; Wang, Xiaohui; Shevchik, Vladimir E.; Pickersgill, Richard W.

    2012-01-01

    Gram-negative bacteria secrete virulence factors and assemble fibre structures on their cell surface using specialized secretion systems. Three of these, T2SS, T3SS and T4PS, are characterized by large outer membrane channels formed by proteins called secretins. Usually, a cognate lipoprotein pilot is essential for the assembly of the secretin in the outer membrane. The structures of the pilotins of the T3SS and T4PS have been described. However in the T2SS, the molecular mechanism of this pr...

  10. The Vibrio parahaemolyticus Type III Secretion Systems manipulate host cell MAPK for critical steps in pathogenesis.

    LENUS (Irish Health Repository)

    Matlawska-Wasowska, Ksenia

    2010-12-01

    Vibrio parahaemolyticus is a food-borne pathogen causing inflammation of the gastrointestinal epithelium. Pathogenic strains of this bacterium possess two Type III Secretion Systems (TTSS) that deliver effector proteins into host cells. In order to better understand human host cell responses to V. parahaemolyticus, the modulation of Mitogen Activated Protein Kinase (MAPK) activation in epithelial cells by an O3:K6 clinical isolate, RIMD2210633, was investigated. The importance of MAPK activation for the ability of the bacterium to be cytotoxic and to induce secretion of Interleukin-8 (IL-8) was determined.

  11. Two Classes of Secreted Synaptic Organizers in the Central Nervous System.

    Science.gov (United States)

    Yuzaki, Michisuke

    2018-02-10

    Research in the last two decades has identified many synaptic organizers in the central nervous system that directly regulate the assembly of pre- and/or postsynaptic molecules, such as synaptic vesicles, active zone proteins, and neurotransmitter receptors. They are classified into secreted factors and cell adhesion molecules, such as neurexins and neuroligins. Certain secreted factors are termed extracellular scaffolding proteins (ESPs) because they are components of the synaptic extracellular matrix and serve as a scaffold at the synaptic cleft. These include Lgi1, Cbln1, neuronal pentraxins, Hevin, thrombospondins, and glypicans. Diffusible secreted factors, such as Wnts, fibroblast growth factors, and semaphorins, tend to act from a distance. In contrast, ESPs remain at the synaptic cleft and often help synaptic adhesion and/or accumulation of postsynaptic receptors. Many fundamental questions remain about when, how, and why various synaptic organizers establish and modify the vast numbers of connections during development and throughout life.

  12. A novel two-component system involved in secretion stress response in Streptomyces lividans.

    Directory of Open Access Journals (Sweden)

    Sonia Gullón

    Full Text Available BACKGROUND: Misfolded proteins accumulating outside the bacterial cytoplasmic membrane can interfere with the secretory machinery, hence the existence of quality factors to eliminate these misfolded proteins is of capital importance in bacteria that are efficient producers of secretory proteins. These bacteria normally use a specific two-component system to respond to the stress produced by the accumulation of the misfolded proteins, by activating the expression of HtrA-like proteases to specifically eliminate the incorrectly folded proteins. METHODOLOGY/PRINCIPAL FINDINGS: Overproduction of alpha-amylase in S. lividans causing secretion stress permitted the identification of a two-component system (SCO4156-SCO4155 that regulates three HtrA-like proteases which appear to be involved in secretion stress response. Mutants in each of the genes forming part of the two-genes operon that encodes the sensor and regulator protein components accumulated misfolded proteins outside the cell, strongly suggesting the involvement of this two-component system in the S. lividans secretion stress response. CONCLUSIONS/SIGNIFICANCE: To our knowledge this is the first time that a specific secretion stress response two-component system is found to control the expression of three HtrA-like protease genes in S. lividans, a bacterium that has been repeatedly used as a host for the synthesis of homologous and heterologous secretory proteins of industrial application.

  13. Systems and methods for the secretion of recombinant proteins in gram negative bacteria

    Science.gov (United States)

    Withers, III, Sydnor T.; Dominguez, Miguel A; DeLisa, Matthew P.; Haitjema, Charles H.

    2016-08-09

    Disclosed herein are systems and methods for producing recombinant proteins utilizing mutant E. coli strains containing expression vectors carrying nucleic acids encoding the proteins, and secretory signal sequences to direct the secretion of the proteins to the culture medium. Host cells transformed with the expression vectors are also provided.

  14. Identification of a functional type VI secretion system in Campylobacter jejuni conferring capsule polysaccharide sensitive cytotoxicity

    NARCIS (Netherlands)

    Bleumink-Pluym, Nancy M C; van Alphen, Lieke B; Bouwman, Lieneke I; Wösten, MM; van Putten, Jos P M

    2013-01-01

    The pathogen Campylobacter jejuni is the principal cause of bacterial food-borne infections. The mechanism(s) that contribute to bacterial survival and disease are still poorly understood. In other bacterial species, type VI secretion systems (T6SS) are increasingly recognized to contribute to

  15. Interactions between the Central Nervous System and Pancreatic Islet Secretions: A Historical Perspective

    Science.gov (United States)

    Begg, Denovan P.; Woods, Stephen C.

    2013-01-01

    The endocrine pancreas is richly innervated with sympathetic and parasympathetic projections from the brain. In the mid-20th century, it was established that alpha-adrenergic activation inhibits, whereas cholinergic stimulation promotes, insulin secretion; this demonstrated the importance of the sympathetic and parasympathetic systems in…

  16. Systems and methods for the secretion of recombinant proteins in gram negative bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Withers, III, Sydnor T.; Dominguez, Miguel A.; DeLisa, Matthew P.; Haitjema, Charles H.

    2017-02-21

    Disclosed herein are systems and methods for producing recombinant proteins utilizing mutant E. coli strains containing expression vectors carrying nucleic acids encoding the proteins, and secretory signal sequences to direct the secretion of the proteins to the culture medium. Host cells transformed with the expression vectors are also provided.

  17. Secret-key and identification rates for biometric identification systems with protected templates

    NARCIS (Netherlands)

    Ignatenko, T.; Willems, F.M.J.

    2010-01-01

    In this paper we consider secret generation in biometric identification systems with protected templates. This problem is closely related to the study of the bio metric identification capacity [Willems et al., 2003] and [O’Sullivan and Sclmmid, 2002] and the common randomness generation scheme

  18. Best kept secrets ... First Coast Systems, Inc. (FCS).

    Science.gov (United States)

    Andrew, W F

    1991-04-01

    The FCS/APaCS system is a viable option for small-to medium-size hospitals (up to 400 beds). The table-driven system takes full advantage of IBM AS/400 computer architecture. A comprehensive application set, provided in an integrated database environment, is adaptable to multi-facility environments. Price/performance appears to be competitive. Commitment to IBM AS/400 environment assures cost-effective hardware platforms backed by IBM support and resources. As an IBM Health Industry Business Partner, FCS (and its clients) benefits from IBM's well-known commitment to quality and service. Corporate emphasis on user involvement and satisfaction, along with a commitment to quality and service for the APaCS systems, assures clients of "leading edge" capabilities in this evolutionary healthcare delivery environment. FCS/APaCS will be a strong contender in selected marketing environments.

  19. Best kept secrets ... Source Data Systems, Inc. (SDS).

    Science.gov (United States)

    Andrew, W F

    1991-03-01

    The SDS/MEDNET system is a cost-effective option for small- to medium-size hospitals (up to 400 beds). The parameter-driven system lets users control operations with only occasional SDS assistance. A full application set, available for modular selection to reduce upfront costs while facilitating steady growth and protecting client investment, is adaptable to multi-facility environments. The industry-standard, Intel-based multi-user processors, network communications and protocols assure high efficiency, low-cost solutions independent of any one hardware vendor. Sustained growth in both client base and product offerings point to a high level of responsiveness and healthcare industry commitment. Corporate emphasis on user involvement and open systems integration assures clients of leading-edge capabilities. SDS/MEDNET will be a strong contender in selected marketing environments.

  20. Genome-scale analysis of the high-efficient protein secretion system of Aspergillus oryzae.

    Science.gov (United States)

    Liu, Lifang; Feizi, Amir; Österlund, Tobias; Hjort, Carsten; Nielsen, Jens

    2014-06-24

    The koji mold, Aspergillus oryzae is widely used for the production of industrial enzymes due to its particularly high protein secretion capacity and ability to perform post-translational modifications. However, systemic analysis of its secretion system is lacking, generally due to the poorly annotated proteome. Here we defined a functional protein secretory component list of A. oryzae using a previously reported secretory model of S. cerevisiae as scaffold. Additional secretory components were obtained by blast search with the functional components reported in other closely related fungal species such as Aspergillus nidulans and Aspergillus niger. To evaluate the defined component list, we performed transcriptome analysis on three α-amylase over-producing strains with varying levels of secretion capacities. Specifically, secretory components involved in the ER-associated processes (including components involved in the regulation of transport between ER and Golgi) were significantly up-regulated, with many of them never been identified for A. oryzae before. Furthermore, we defined a complete list of the putative A. oryzae secretome and monitored how it was affected by overproducing amylase. In combination with the transcriptome data, the most complete secretory component list and the putative secretome, we improved the systemic understanding of the secretory machinery of A. oryzae in response to high levels of protein secretion. The roles of many newly predicted secretory components were experimentally validated and the enriched component list provides a better platform for driving more mechanistic studies of the protein secretory pathway in this industrially important fungus.

  1. SIMPL Systems, or: Can We Design Cryptographic Hardware without Secret Key Information?

    Science.gov (United States)

    Rührmair, Ulrich

    This paper discusses a new cryptographic primitive termed SIMPL system. Roughly speaking, a SIMPL system is a special type of Physical Unclonable Function (PUF) which possesses a binary description that allows its (slow) public simulation and prediction. Besides this public key like functionality, SIMPL systems have another advantage: No secret information is, or needs to be, contained in SIMPL systems in order to enable cryptographic protocols - neither in the form of a standard binary key, nor as secret information hidden in random, analog features, as it is the case for PUFs. The cryptographic security of SIMPLs instead rests on (i) a physical assumption on their unclonability, and (ii) a computational assumption regarding the complexity of simulating their output. This novel property makes SIMPL systems potentially immune against many known hardware and software attacks, including malware, side channel, invasive, or modeling attacks.

  2. AtlA functions as a peptidoglycan lytic transglycosylase in the Neisseria gonorrhoeae type IV secretion system.

    Science.gov (United States)

    Kohler, Petra L; Hamilton, Holly L; Cloud-Hansen, Karen; Dillard, Joseph P

    2007-08-01

    Type IV secretion systems require peptidoglycan lytic transglycosylases for efficient secretion, but the function of these enzymes is not clear. The type IV secretion system gene cluster of Neisseria gonorrhoeae encodes two peptidoglycan transglycosylase homologues. One, LtgX, is similar to peptidoglycan transglycosylases from other type IV secretion systems. The other, AtlA, is similar to endolysins from bacteriophages and is not similar to any described type IV secretion component. We characterized the enzymatic function of AtlA in order to examine its role in the type IV secretion system. Purified AtlA was found to degrade macromolecular peptidoglycan and to produce 1,6-anhydro peptidoglycan monomers, characteristic of lytic transglycosylase activity. We found that AtlA can functionally replace the lambda endolysin to lyse Escherichia coli. In contrast, a sensitive measure of lysis demonstrated that AtlA does not lyse gonococci expressing it or gonococci cocultured with an AtlA-expressing strain. The gonococcal type IV secretion system secretes DNA during growth. A deletion of ltgX or a substitution in the putative active site of AtlA severely decreased DNA secretion. These results indicate that AtlA and LtgX are actively involved in type IV secretion and that AtlA is not involved in lysis of gonococci to release DNA. This is the first demonstration that a type IV secretion peptidoglycanase has lytic transglycosylase activity. These data show that AtlA plays a role in type IV secretion of DNA that requires peptidoglycan breakdown without cell lysis.

  3. Conservation of the Type IV secretion system throughout Wolbachia evolution

    DEFF Research Database (Denmark)

    Pichon, Samuel; Bouchon, Didier; Cordaux, Richard

    2009-01-01

    , encoding a T4SS were previously identified and characterized at two separate genomic loci. Using the largest data set of Wolbachia strains studied so far, we show that vir gene sequence and organization are strictly conserved among 37 Wolbachia strains inducing various phenotypes such as cytoplasmic...... incompatibility, feminization, or oogenesis in their arthropod hosts. In sharp contrast, extensive variation of genomic sequences flanking the virB8-D4 operon suggested its distinct location among Wolbachia genomes. Long term conservation of the T4SS may imply maintenance of a functional effector translocation...... system in Wolbachia, thereby suggesting the importance for the T4SS in Wolbachia biology and survival inside host cells....

  4. METER-SIZED MOONLET POPULATION IN SATURN'S C RING AND CASSINI DIVISION

    International Nuclear Information System (INIS)

    Baillié, Kévin; Colwell, Joshua E.; Esposito, Larry W.; Lewis, Mark C.

    2013-01-01

    Stellar occultations observed by the Cassini Ultraviolet Imaging Spectrograph reveal the presence of transparent holes a few meters to a few tens of meters in radial extent in otherwise optically thick regions of the C ring and the Cassini Division. We attribute the holes to gravitational disturbances generated by a population of ∼10 m boulders in the rings that is intermediate in size between the background ring particle size distribution and the previously observed ∼100 m propeller moonlets in the A ring. The size distribution of these boulders is described by a shallower power-law than the one that describes the ring particle size distribution. The number and size distribution of these boulders could be explained by limited accretion processes deep within Saturn's Roche zone.

  5. The type III protein secretion system contributes to Xanthomonas citri subsp. citri biofilm formation

    KAUST Repository

    Zimaro, Tamara

    2014-04-18

    Background: Several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a Type III protein secretion system (T3SS). The role of T3SS in bacterial pathogenesis is well established but whether this system is involved in multicellular processes, such as bacterial biofilm formation has not been elucidated. Here, the phytopathogen Xanthomonas citri subsp. citri (X. citri) was used as a model to gain further insights about the role of the T3SS in biofilm formation. Results: The capacity of biofilm formation of different X. citri T3SS mutants was compared to the wild type strain and it was observed that this secretion system was necessary for this process. Moreover, the T3SS mutants adhered proficiently to leaf surfaces but were impaired in leaf-associated growth. A proteomic study of biofilm cells showed that the lack of the T3SS causes changes in the expression of proteins involved in metabolic processes, energy generation, exopolysaccharide (EPS) production and bacterial motility as well as outer membrane proteins. Furthermore, EPS production and bacterial motility were also altered in the T3SS mutants. Conclusions: Our results indicate a novel role for T3SS in X. citri in the modulation of biofilm formation. Since this process increases X. citri virulence, this study reveals new functions of T3SS in pathogenesis. 2014 Zimaro et al.; licensee BioMed Central Ltd.

  6. Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

    International Nuclear Information System (INIS)

    Bollini, Carlos Guido; Giambiagi, Mario; Giambiagi, Myriam Segre de; Figueiredo, Aloysio Paiva de

    2001-02-01

    Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I ring values. (author)

  7. Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

    CERN Document Server

    Bollini, C G; Giambiagi, M

    2001-01-01

    Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I sub r sub i sub n sub g values.

  8. Expression and Quorum Sensing Regulation of Type III Secretion System Genes of Vibrio harveyi during Infection of Gnotobiotic Brine Shrimp.

    Directory of Open Access Journals (Sweden)

    H A Darshanee Ruwandeepika

    Full Text Available Type III secretion systems enable pathogens to inject their virulence factors directly into the cytoplasm of the host cells. The type III secretion system of Vibrio harveyi, a major pathogen of aquatic organisms and a model species in quorum sensing studies, is repressed by the quorum sensing master regulator LuxR. In this study, we found that during infection of gnotobiotic brine shrimp larvae, the expression levels of three type III secretion operons in V. harveyi increased within the first 12h after challenge and decreased again thereafter. The in vivo expression levels were highest in a mutant with a quorum sensing system that is locked in low cell density configuration (minimal LuxR levels and lowest in a mutant with a quorum sensing system that is locked in the high cell density configuration (maximal LuxR levels, which is consistent with repression of type III secretion by LuxR. Remarkably, in vivo expression levels of the type III secretion system genes were much (> 1000 fold higher than the in vitro expression levels, indicating that (currently unknown host factors significantly induce the type III secretion system. Given the fact that type III secretion is energy-consuming, repression by the quorum sensing master regulators might be a mechanism to save energy under conditions where it does not provide an advantage to the cells.

  9. Extracellular overexpression of recombinant Thermobifida fusca cutinase by alpha-hemolysin secretion system in E. coli BL21(DE3

    Directory of Open Access Journals (Sweden)

    Su Lingqia

    2012-01-01

    Full Text Available Abstract Background Extracellular expression of proteins has an absolute advantage in a large-scale industrial production. In our previous study, Thermobifida fusca cutinase, an enzyme mainly utilized in textile industry, was expressed via type II secretory system in Escherichia coli BL21(DE3, and it was found that parts of the expressed protein was accumulated in the periplasmic space. Due to the fact that alpha-hemolysin secretion system can export target proteins directly from cytoplasm across both cell membrane of E. coli to the culture medium, thus in the present study we investigated the expression of cutinase using this alpha-hemolysin secretion system. Results T. fusca cutinase was fused with the specific signal peptide of alpha-hemolysin scretion system and expressed in E. coli BL21(DE3. In addition, HlyB and HlyD, strain-specific translocation components of alpha-hemolysin secretion system, were coexpressed to facilitate the enzyme expression. The cultivation of this engineered cell showed that cutinase activity in the culture medium reached 334 U/ml, which is 2.5 times that from type II secretion pathway under the same culture condition. The recombinant cutinase was further purified. Biochemical characterization of purified enzyme, which had an α-hemolysin secretion pathway signal peptide attached, had substrate specificity, pH and temperature profile, as well as application capability in bioscouring similar to that of wild-type cutinase. Conclusions In the present study, T. fusca cutinase was successfully secreted to the culture media by α-hemolysin secretion system. This is the first report of cutinase being efficiently secreted by this pathway. Due to the limited cases of successful expression of industrial enzyme by E. coli α-hemolysin secretion system, our study further explored the utilization of this pathway in industrial enzymes.

  10. High levels of DegU-P activate an Esat-6-like secretion system in Bacillus subtilis.

    Directory of Open Access Journals (Sweden)

    Catarina Baptista

    Full Text Available The recently discovered Type VII/Esat-6 secretion systems seem to be widespread among bacteria of the phyla Actinobacteria and Firmicutes. In some species they play an important role in pathogenic interactions with eukaryotic hosts. Several studies have predicted that the locus yukEDCByueBC of the non-pathogenic, Gram-positive bacterium Bacillus subtilis would encode an Esat-6-like secretion system (Ess. We provide here for the first time evidences for the functioning of this secretion pathway in an undomesticated B. subtilis strain. We show that YukE, a small protein with the typical features of the secretion substrates from the WXG100 superfamily is actively secreted to culture media. YukE secretion depends on intact yukDCByueBC genes, whose products share sequence or structural homology with known components of the S. aureus Ess. Biochemical characterization of YukE indicates that it exists as a dimer both in vitro and in vivo. We also show that the B. subtilis Ess essentially operates in late stationary growth phase in absolute dependence of phosphorylated DegU, the response regulator of the two-component system DegS-DegU. We present possible reasons that eventually have precluded the study of this secretion system in the B. subtilis laboratory strain 168.

  11. Role of the Enteric Nervous System in the Fluid and Electrolyte Secretion of Rotavirus Diarrhea

    Science.gov (United States)

    Lundgren, Ove; Peregrin, Attila Timar; Persson, Kjell; Kordasti, Shirin; Uhnoo, Ingrid; Svensson, Lennart

    2000-01-01

    The mechanism underlying the intestinal fluid loss in rotavirus diarrhea, which often afflicts children in developing countries, is not known. One hypothesis is that the rotavirus evokes intestinal fluid and electrolyte secretion by activation of the nervous system in the intestinal wall, the enteric nervous system (ENS). Four different drugs that inhibit ENS functions were used to obtain experimental evidence for this hypothesis in mice in vitro and in vivo. The involvement of the ENS in rotavirus diarrhea indicates potential sites of action for drugs in the treatment of the disease.

  12. Vibrio vulnificus Type 6 Secretion System 1 Contains Anti-Bacterial Properties.

    Directory of Open Access Journals (Sweden)

    Selina R Church

    Full Text Available Vibrio vulnificus is a bacterium responsible for severe gastroenteritis, sepsis and wound infections. Gastroenteritis and sepsis are commonly associated with the consumption of raw oysters, whereas wound infection is often associated with the handling of contaminated fish. Although classical virulence factors of this emerging pathogen are well characterised, there remains a paucity of knowledge regarding the general biology of this species. To investigate the presence of previously unreported virulence factors, we applied whole genome sequencing to a panel of ten V. vulnificus strains with varying virulence potentials. This identified two novel type 6 secretion systems (T6SSs, systems that are known to have a role in bacterial virulence and population dynamics. By utilising a range of molecular techniques and assays we have demonstrated the functionality of one of these T6SSs. Furthermore, we have shown that this system is subject to thermoregulation and is negatively regulated by increasing salinity concentrations. This secretion system was also shown to be involved in the killing of V. vulnificus strains that did not possess this system and a model is proposed as to how this interaction may contribute to population dynamics within V. vulnificus strains. In addition to this intra-species killing, this system also contributes to the killing of inter bacterial species and may have a role in the general composition of Vibrio species in the environment.

  13. Always one step ahead: How pathogenic bacteria use the type III secretion system to manipulate the intestinal mucosal immune system

    Directory of Open Access Journals (Sweden)

    Marchès Olivier

    2011-05-01

    Full Text Available Abstract The intestinal immune system and the epithelium are the first line of defense in the gut. Constantly exposed to microorganisms from the environment, the gut has complex defense mechanisms to prevent infections, as well as regulatory pathways to tolerate commensal bacteria and food antigens. Intestinal pathogens have developed strategies to regulate intestinal immunity and inflammation in order to establish or prolong infection. The organisms that employ a type III secretion system use a molecular syringe to deliver effector proteins into the cytoplasm of host cells. These effectors target the host cell cytoskeleton, cell organelles and signaling pathways. This review addresses the multiple mechanisms by which the type III secretion system targets the intestinal immune response, with a special focus on pathogenic E. coli.

  14. A Novel ESAT-6 Secretion System-Secreted Protein EsxX of Community-Associated Staphylococcus aureus Lineage ST398 Contributes to Immune Evasion and Virulence

    Directory of Open Access Journals (Sweden)

    Yingxin Dai

    2017-05-01

    Full Text Available The ESAT-6 secretion system (ESS has been reported to contribute to the virulence and pathogenicity of several Staphylococcus aureus strains such as USA300 and Newman. However, the role of the ESS in community-associated S. aureus (CA-SA lineage ST398 in China is not well understood. By comparing the ess locus of ST398 with the published S. aureus sequence in the NCBI database, we found one gene in the ess locus encoding a novel WXG superfamily protein that is highly conserved only in ST398. LC-MS/MS and Western blot analysis revealed that this protein is a novel secreted protein controlled by the ST398 ESS, and we named the protein EsxX. Although EsxX was not under the control of the accessory gene regulator like many other virulence factors and had no influence on several phenotypes of ST398, such as growth, hemolysis, and biofilm formation, it showed important impacts on immune evasion and virulence in ST398. An esxX deletion mutant led to significantly reduced resistance to neutrophil killing and decreased virulence in murine skin and blood infection models, indicating its essential contribution to the evasion of innate host defense and virulence to support the pathogenesis of ST398 infections. The function of this novel secreted protein EsxX might help us better understand the role of the ESS in the virulence and epidemic success of the CA-SA lineage ST398.

  15. A Novel ESAT-6 Secretion System-Secreted Protein EsxX of Community-Associated Staphylococcus aureus Lineage ST398 Contributes to Immune Evasion and Virulence.

    Science.gov (United States)

    Dai, Yingxin; Wang, Yanan; Liu, Qian; Gao, Qianqian; Lu, Huiying; Meng, Hongwei; Qin, Juanxiu; Hu, Mo; Li, Min

    2017-01-01

    The ESAT-6 secretion system (ESS) has been reported to contribute to the virulence and pathogenicity of several Staphylococcus aureus strains such as USA300 and Newman. However, the role of the ESS in community-associated S. aureus (CA-SA) lineage ST398 in China is not well understood. By comparing the ess locus of ST398 with the published S. aureus sequence in the NCBI database, we found one gene in the ess locus encoding a novel WXG superfamily protein that is highly conserved only in ST398. LC-MS/MS and Western blot analysis revealed that this protein is a novel secreted protein controlled by the ST398 ESS, and we named the protein EsxX. Although EsxX was not under the control of the accessory gene regulator like many other virulence factors and had no influence on several phenotypes of ST398, such as growth, hemolysis, and biofilm formation, it showed important impacts on immune evasion and virulence in ST398. An esxX deletion mutant led to significantly reduced resistance to neutrophil killing and decreased virulence in murine skin and blood infection models, indicating its essential contribution to the evasion of innate host defense and virulence to support the pathogenesis of ST398 infections. The function of this novel secreted protein EsxX might help us better understand the role of the ESS in the virulence and epidemic success of the CA-SA lineage ST398.

  16. Identification of a functional type VI secretion system in Campylobacter jejuni conferring capsule polysaccharide sensitive cytotoxicity.

    Directory of Open Access Journals (Sweden)

    Nancy M C Bleumink-Pluym

    Full Text Available The pathogen Campylobacter jejuni is the principal cause of bacterial food-borne infections. The mechanism(s that contribute to bacterial survival and disease are still poorly understood. In other bacterial species, type VI secretion systems (T6SS are increasingly recognized to contribute to bacterial pathogenesis by toxic effects on host cells or competing bacterial species. Here we report the presence of a functional Type VI secretion system in C. jejuni. Proteome and genetic analyses revealed that C. jejuni strain 108 contains a 17-kb T6SS gene cluster consisting of 13 T6SS-conserved genes, including the T6SS hallmark genes hcp and vgrG. The cluster lacks an ortholog of the ClpV ATPase considered important for T6SS function. The sequence and organization of the C. jejuni T6SS genes resemble those of the T6SS located on the HHGI1 pathogenicity island of Helicobacter hepaticus. The C. jejuni T6SS is integrated into the earlier acquired Campylobacter integrated element CJIE3 and is present in about 10% of C. jejuni isolates including several isolates derived from patients with the rare clinical feature of C. jejuni bacteremia. Targeted mutagenesis of C. jejuni T6SS genes revealed T6SS-dependent secretion of the Hcp needle protein into the culture supernatant. Infection assays provided evidence that the C. jejuni T6SS confers contact-dependent cytotoxicity towards red blood cells but not macrophages. This trait was observed only in a capsule-deficient bacterial phenotype. The unique C. jejuni T6SS phenotype of capsule-sensitive contact-mediated hemolysis represents a novel evolutionary pathway of T6SS in bacteria and expands the repertoire of virulence properties associated with T6SS.

  17. Identification of a functional type VI secretion system in Campylobacter jejuni conferring capsule polysaccharide sensitive cytotoxicity.

    Science.gov (United States)

    Bleumink-Pluym, Nancy M C; van Alphen, Lieke B; Bouwman, Lieneke I; Wösten, Marc M S M; van Putten, Jos P M

    2013-01-01

    The pathogen Campylobacter jejuni is the principal cause of bacterial food-borne infections. The mechanism(s) that contribute to bacterial survival and disease are still poorly understood. In other bacterial species, type VI secretion systems (T6SS) are increasingly recognized to contribute to bacterial pathogenesis by toxic effects on host cells or competing bacterial species. Here we report the presence of a functional Type VI secretion system in C. jejuni. Proteome and genetic analyses revealed that C. jejuni strain 108 contains a 17-kb T6SS gene cluster consisting of 13 T6SS-conserved genes, including the T6SS hallmark genes hcp and vgrG. The cluster lacks an ortholog of the ClpV ATPase considered important for T6SS function. The sequence and organization of the C. jejuni T6SS genes resemble those of the T6SS located on the HHGI1 pathogenicity island of Helicobacter hepaticus. The C. jejuni T6SS is integrated into the earlier acquired Campylobacter integrated element CJIE3 and is present in about 10% of C. jejuni isolates including several isolates derived from patients with the rare clinical feature of C. jejuni bacteremia. Targeted mutagenesis of C. jejuni T6SS genes revealed T6SS-dependent secretion of the Hcp needle protein into the culture supernatant. Infection assays provided evidence that the C. jejuni T6SS confers contact-dependent cytotoxicity towards red blood cells but not macrophages. This trait was observed only in a capsule-deficient bacterial phenotype. The unique C. jejuni T6SS phenotype of capsule-sensitive contact-mediated hemolysis represents a novel evolutionary pathway of T6SS in bacteria and expands the repertoire of virulence properties associated with T6SS.

  18. Reassessing the role of DotF in the Legionella pneumophila type IV secretion system.

    Directory of Open Access Journals (Sweden)

    Molly C Sutherland

    Full Text Available Legionella pneumophila, the causative agent of a severe pneumonia termed Legionnaires' Disease, survives and replicates within both protozoan hosts and human alveolar macrophages. Intracellular survival is dependent upon secretion of a plethora of protein effectors that function to form a replicative vacuole, evade the endocytic pathway and subvert host immune defenses. Export of these factors requires a type IV secretion system (T4SS called Dot/Icm that is composed of twenty-seven proteins. This report focuses on the DotF protein, which was previously postulated to have several different functions, one of which centered on binding Dot/Icm substrates. In this report, we examined if DotF functions as the T4SS inner membrane receptor for Dot/Icm substrates. Although we were able to recapitulate the previously published bacterial two-hybrid interaction between DotF and several substrates, the interaction was not dependent on the Dot/Icm substrates' signal sequences as predicted for a substrate:receptor interaction. In addition, binding did not require the cytoplasmic domain of DotF, which was anticipated to be involved in recognizing substrates in the cytoplasm. Finally, inactivation of dotF did not abolish intracellular growth of L. pneumophila or translocation of substrates, two phenotypes dependent on the T4SS receptor. These data strongly suggest that DotF does not act as the major receptor for Dot/Icm substrates and therefore likely performs an accessory function within the core-transmembrane subcomplex of the L. pneumophila Dot/Icm type IV secretion system.

  19. Essential Role of the ESX-5 Secretion System in Outer Membrane Permeability of Pathogenic Mycobacteria

    KAUST Repository

    Ates, Louis S.

    2015-05-04

    Mycobacteria possess different type VII secretion (T7S) systems to secrete proteins across their unusual cell envelope. One of these systems, ESX-5, is only present in slow-growing mycobacteria and responsible for the secretion of multiple substrates. However, the role of ESX-5 substrates in growth and/or virulence is largely unknown. In this study, we show that esx-5 is essential for growth of both Mycobacterium marinum and Mycobacterium bovis. Remarkably, this essentiality can be rescued by increasing the permeability of the outer membrane, either by altering its lipid composition or by the introduction of the heterologous porin MspA. Mutagenesis of the first nucleotide-binding domain of the membrane ATPase EccC5 prevented both ESX-5-dependent secretion and bacterial growth, but did not affect ESX-5 complex assembly. This suggests that the rescuing effect is not due to pores formed by the ESX-5 membrane complex, but caused by ESX-5 activity. Subsequent proteomic analysis to identify crucial ESX-5 substrates confirmed that all detectable PE and PPE proteins in the cell surface and cell envelope fractions were routed through ESX-5. Additionally, saturated transposon-directed insertion-site sequencing (TraDIS) was applied to both wild-type M. marinum cells and cells expressing mspA to identify genes that are not essential anymore in the presence of MspA. This analysis confirmed the importance of esx-5, but we could not identify essential ESX-5 substrates, indicating that multiple of these substrates are together responsible for the essentiality. Finally, examination of phenotypes on defined carbon sources revealed that an esx-5 mutant is strongly impaired in the uptake and utilization of hydrophobic carbon sources. Based on these data, we propose a model in which the ESX-5 system is responsible for the transport of cell envelope proteins that are required for nutrient uptake. These proteins might in this way compensate for the lack of MspA-like porins in slow

  20. Essential Role of the ESX-5 Secretion System in Outer Membrane Permeability of Pathogenic Mycobacteria.

    Directory of Open Access Journals (Sweden)

    Louis S Ates

    2015-05-01

    Full Text Available Mycobacteria possess different type VII secretion (T7S systems to secrete proteins across their unusual cell envelope. One of these systems, ESX-5, is only present in slow-growing mycobacteria and responsible for the secretion of multiple substrates. However, the role of ESX-5 substrates in growth and/or virulence is largely unknown. In this study, we show that esx-5 is essential for growth of both Mycobacterium marinum and Mycobacterium bovis. Remarkably, this essentiality can be rescued by increasing the permeability of the outer membrane, either by altering its lipid composition or by the introduction of the heterologous porin MspA. Mutagenesis of the first nucleotide-binding domain of the membrane ATPase EccC5 prevented both ESX-5-dependent secretion and bacterial growth, but did not affect ESX-5 complex assembly. This suggests that the rescuing effect is not due to pores formed by the ESX-5 membrane complex, but caused by ESX-5 activity. Subsequent proteomic analysis to identify crucial ESX-5 substrates confirmed that all detectable PE and PPE proteins in the cell surface and cell envelope fractions were routed through ESX-5. Additionally, saturated transposon-directed insertion-site sequencing (TraDIS was applied to both wild-type M. marinum cells and cells expressing mspA to identify genes that are not essential anymore in the presence of MspA. This analysis confirmed the importance of esx-5, but we could not identify essential ESX-5 substrates, indicating that multiple of these substrates are together responsible for the essentiality. Finally, examination of phenotypes on defined carbon sources revealed that an esx-5 mutant is strongly impaired in the uptake and utilization of hydrophobic carbon sources. Based on these data, we propose a model in which the ESX-5 system is responsible for the transport of cell envelope proteins that are required for nutrient uptake. These proteins might in this way compensate for the lack of Msp

  1. Essential Role of the ESX-5 Secretion System in Outer Membrane Permeability of Pathogenic Mycobacteria

    KAUST Repository

    Ates, Louis S.; Ummels, Roy; Commandeur, Susanna; van der Weerd, Robert; Sparrius, Marion; Weerdenburg, Eveline; Alber, Marina; Kalscheuer, Rainer; Piersma, Sander R.; Abdallah, Abdallah; Abd El Ghany, Moataz; Abdel-Haleem, Alyaa M.; Pain, Arnab; Jimé nez, Connie R.; Bitter, Wilbert; Houben, Edith N.G.

    2015-01-01

    Mycobacteria possess different type VII secretion (T7S) systems to secrete proteins across their unusual cell envelope. One of these systems, ESX-5, is only present in slow-growing mycobacteria and responsible for the secretion of multiple substrates. However, the role of ESX-5 substrates in growth and/or virulence is largely unknown. In this study, we show that esx-5 is essential for growth of both Mycobacterium marinum and Mycobacterium bovis. Remarkably, this essentiality can be rescued by increasing the permeability of the outer membrane, either by altering its lipid composition or by the introduction of the heterologous porin MspA. Mutagenesis of the first nucleotide-binding domain of the membrane ATPase EccC5 prevented both ESX-5-dependent secretion and bacterial growth, but did not affect ESX-5 complex assembly. This suggests that the rescuing effect is not due to pores formed by the ESX-5 membrane complex, but caused by ESX-5 activity. Subsequent proteomic analysis to identify crucial ESX-5 substrates confirmed that all detectable PE and PPE proteins in the cell surface and cell envelope fractions were routed through ESX-5. Additionally, saturated transposon-directed insertion-site sequencing (TraDIS) was applied to both wild-type M. marinum cells and cells expressing mspA to identify genes that are not essential anymore in the presence of MspA. This analysis confirmed the importance of esx-5, but we could not identify essential ESX-5 substrates, indicating that multiple of these substrates are together responsible for the essentiality. Finally, examination of phenotypes on defined carbon sources revealed that an esx-5 mutant is strongly impaired in the uptake and utilization of hydrophobic carbon sources. Based on these data, we propose a model in which the ESX-5 system is responsible for the transport of cell envelope proteins that are required for nutrient uptake. These proteins might in this way compensate for the lack of MspA-like porins in slow

  2. AtlasT4SS: a curated database for type IV secretion systems.

    Science.gov (United States)

    Souza, Rangel C; del Rosario Quispe Saji, Guadalupe; Costa, Maiana O C; Netto, Diogo S; Lima, Nicholas C B; Klein, Cecília C; Vasconcelos, Ana Tereza R; Nicolás, Marisa F

    2012-08-09

    The type IV secretion system (T4SS) can be classified as a large family of macromolecule transporter systems, divided into three recognized sub-families, according to the well-known functions. The major sub-family is the conjugation system, which allows transfer of genetic material, such as a nucleoprotein, via cell contact among bacteria. Also, the conjugation system can transfer genetic material from bacteria to eukaryotic cells; such is the case with the T-DNA transfer of Agrobacterium tumefaciens to host plant cells. The system of effector protein transport constitutes the second sub-family, and the third one corresponds to the DNA uptake/release system. Genome analyses have revealed numerous T4SS in Bacteria and Archaea. The purpose of this work was to organize, classify, and integrate the T4SS data into a single database, called AtlasT4SS - the first public database devoted exclusively to this prokaryotic secretion system. The AtlasT4SS is a manual curated database that describes a large number of proteins related to the type IV secretion system reported so far in Gram-negative and Gram-positive bacteria, as well as in Archaea. The database was created using the RDBMS MySQL and the Catalyst Framework based in the Perl programming language and using the Model-View-Controller (MVC) design pattern for Web. The current version holds a comprehensive collection of 1,617 T4SS proteins from 58 Bacteria (49 Gram-negative and 9 Gram-Positive), one Archaea and 11 plasmids. By applying the bi-directional best hit (BBH) relationship in pairwise genome comparison, it was possible to obtain a core set of 134 clusters of orthologous genes encoding T4SS proteins. In our database we present one way of classifying orthologous groups of T4SSs in a hierarchical classification scheme with three levels. The first level comprises four classes that are based on the organization of genetic determinants, shared homologies, and evolutionary relationships: (i) F-T4SS, (ii) P-T4SS, (iii

  3. Crystal Structure of Hcp from Acinetobacter baumannii: A Component of the Type VI Secretion System.

    Directory of Open Access Journals (Sweden)

    Federico M Ruiz

    Full Text Available The type VI secretion system (T6SS is a bacterial macromolecular machine widely distributed in Gram-negative bacteria, which transports effector proteins into eukaryotic host cells or other bacteria. Membrane complexes and a central tubular structure, which resembles the tail of contractile bacteriophages, compose the T6SS. One of the proteins forming this tube is the hemolysin co-regulated protein (Hcp, which acts as virulence factor, as transporter of effectors and as a chaperone. In this study, we present the structure of Hcp from Acinetobacter baumannii, together with functional and oligomerization studies. The structure of this protein exhibits a tight β barrel formed by two β sheets and flanked at one side by a short α-helix. Six Hcp molecules associate to form a donut-shaped hexamer, as observed in both the crystal structure and solution. These results emphasize the importance of this oligomerization state in this family of proteins, despite the low similarity of sequence among them. The structure presented in this study is the first one for a protein forming part of a functional T6SS from A. baumannii. These results will help us to understand the mechanism and function of this secretion system in this opportunistic nosocomial pathogen.

  4. Characterization of the SPI-1 and Rsp type three secretion systems in Pseudomonas fluorescens F113.

    Science.gov (United States)

    Barret, Matthieu; Egan, Frank; Moynihan, Jennifer; Morrissey, John P; Lesouhaitier, Olivier; O'Gara, Fergal

    2013-06-01

    Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar beet rhizosphere. The recent annotation of the F113 genome sequence has revealed that this strain encodes a wide array of secretion systems, including two complete type three secretion systems (T3SSs) belonging to the Hrp1 and SPI-1 families. While Hrp1 T3SSs are frequently encoded in other P. fluorescens strains, the presence of a SPI-1 T3SS in a plant-beneficial bacterial strain was unexpected. In this work, the genetic organization and expression of these two T3SS loci have been analysed by a combination of transcriptional reporter fusions and transcriptome analyses. Overexpression of two transcriptional activators has shown a number of genes encoding putative T3 effectors. In addition, the influence of these two T3SSs during the interaction of P. fluorescens F113 with some bacterial predators was also assessed. Our data revealed that the transcriptional activator hilA is induced by amoeba and that the SPI-1 T3SS could potentially be involved in resistance to amoeboid grazing. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

  5. Flotillin scaffold activity contributes to type VII secretion system assembly in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Benjamin Mielich-Süss

    2017-11-01

    Full Text Available Scaffold proteins are ubiquitous chaperones that promote efficient interactions between partners of multi-enzymatic protein complexes; although they are well studied in eukaryotes, their role in prokaryotic systems is poorly understood. Bacterial membranes have functional membrane microdomains (FMM, a structure homologous to eukaryotic lipid rafts. Similar to their eukaryotic counterparts, bacterial FMM harbor a scaffold protein termed flotillin that is thought to promote interactions between proteins spatially confined to the FMM. Here we used biochemical approaches to define the scaffold activity of the flotillin homolog FloA of the human pathogen Staphylococcus aureus, using assembly of interacting protein partners of the type VII secretion system (T7SS as a case study. Staphylococcus aureus cells that lacked FloA showed reduced T7SS function, and thus reduced secretion of T7SS-related effectors, probably due to the supporting scaffold activity of flotillin. We found that the presence of flotillin mediates intermolecular interactions of T7SS proteins. We tested several small molecules that interfere with flotillin scaffold activity, which perturbed T7SS activity in vitro and in vivo. Our results suggest that flotillin assists in the assembly of S. aureus membrane components that participate in infection and influences the infective potential of this pathogen.

  6. In silico dissection of Type VII Secretion System components across bacteria: New directions towards functional characterization.

    Science.gov (United States)

    Das, Chandrani; Ghosh, Tarini Shankar; Mande, Sharmila S

    2016-03-01

    Type VII Secretion System (T7SS) is one of the factors involved in virulence of Mycobacterium tuberculosis H37Rv. Numerous research efforts have been made in the last decade towards characterizing the components of this secretion system. An extensive genome-wide analysis through compilation of isolated information is required to obtain a global view of diverse characteristics and pathogenicity-related aspects of this machinery. The present study suggests that differences in structural components (of T7SS) between Actinobacteria and Firmicutes, observed earlier in a few organisms, is indeed a global trend. A few hitherto uncharacterized T7SS-like clusters have been identified in the pathogenic bacteria Enterococcus faecalis, Saccharomonospora viridis, Streptococcus equi, Streptococcus gordonii and Streptococcus sanguinis. Experimental verification of these clusters can shed lights on their role in bacterial pathogenesis. Similarly, verification of the identified variants of T7SS clusters consisting additional membrane components may help in unraveling new mechanism of protein translocation through T7SS. A database of various components of T7SS has been developed to facilitate easy access and interpretation of T7SS related data.

  7. Meningococcal Two-Partner Secretion Systems and Their Association with Outcome in Patients with Meningitis

    Science.gov (United States)

    Piet, Jurgen R.; van Ulsen, Peter; ur Rahman, Sadeeq; Bovenkerk, Sandra; Bentley, Stephen D.

    2016-01-01

    Two-partner secretion (TPS) systems export large TpsA proteins to the surface and extracellular milieu. In meningococci, three different TPS systems exist, and of these, TPS system 2 (TPS2) and TPS3 can be detected by the host's immune system. We evaluated the distribution of TPS systems among clinical isolates from two prospective cohort studies comprising 373 patients with meningococcal meningitis. TPS system 1 was present in 91% of isolates, and system 2 and/or 3 was present in 67%. The TPS system distribution was related to clonal complexes. Infection with strains with TPS2 and/or TPS3 resulted in less severe disease and better outcomes than infection with strains without these systems. Using whole-blood stimulation experiments, we found no differences in the host cytokine response between patients infected with TPS system 2 and 3 knockout strains and patients infected with a wild-type strain. In conclusion, meningococcal TPS system 2 and/or 3 is associated with disease severity and outcome in patients with meningitis. PMID:27324486

  8. Super-Resolution Imaging of Protein Secretion Systems and the Cell Surface of Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Sachith D. Gunasinghe

    2017-05-01

    Full Text Available Gram-negative bacteria have a highly evolved cell wall with two membranes composed of complex arrays of integral and peripheral proteins, as well as phospholipids and glycolipids. In order to sense changes in, respond to, and exploit their environmental niches, bacteria rely on structures assembled into or onto the outer membrane. Protein secretion across the cell wall is a key process in virulence and other fundamental aspects of bacterial cell biology. The final stage of protein secretion in Gram-negative bacteria, translocation across the outer membrane, is energetically challenging so sophisticated nanomachines have evolved to meet this challenge. Advances in fluorescence microscopy now allow for the direct visualization of the protein secretion process, detailing the dynamics of (i outer membrane biogenesis and the assembly of protein secretion systems into the outer membrane, (ii the spatial distribution of these and other membrane proteins on the bacterial cell surface, and (iii translocation of effector proteins, toxins and enzymes by these protein secretion systems. Here we review the frontier research imaging the process of secretion, particularly new studies that are applying various modes of super-resolution microscopy.

  9. Open Secrets

    OpenAIRE

    Madison, Michael

    2017-01-01

    The law of trade secrets is often conceptualized in bilateral terms, as creating and enforcing rights between trade secret owners, on the one hand, and misappropriators on the other hand. This paper, a chapter in a forthcoming collection on the law of trade secrets, argues that trade secrets and the law that guards them can serve structural and insitutional roles as well. Somewhat surprisingly, given the law’s focus on secrecy, among the institutional products of trade secrets law are commons...

  10. Initial report on stress-corrosion-cracking experiments using Zircaloy-4 spent fuel cladding C-rings

    International Nuclear Information System (INIS)

    Smith, H.D.

    1988-09-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Project is sponsoring C-ring stress corrosion cracking scoping experiments as a first step in evaluating the potential for stress corrosion cracking of spent fuel cladding in a potential tuff repository environment. The objective is to scope the approximate behavior so that more precise pressurized tube testing can be performed over an appropriate range of stress, without expanding the long-term effort needlessly. The experiment consists of stressing, by compression with a dead weight load, C-rings fabricated from spent fuel cladding exposed to an environment of Well J-13 water held at 90/degree/C. The results indicate that stress corrosion cracking occurs at the high stress levels employed in the experiments. The cladding C-rings, tested at 90% of the stress at which elastic behavior is obtained in these specimens, broke in 25 to 64 d when tested in water. This was about one third of the time required for control tests to break in air. This is apparently the first observation of stress corrosion under the test conditions of relatively low temperature, benign environment but very high stress. The 150 ksi test stress could be applied as a result of the particular specimen geometry. By comparison, the uniaxial tensile yield stress is about 100 to 120 ksi and the ultimate stress is about 150 ksi. When a general model that fits the high stress results is extrapolated to lower stress levels, it indicates that the C-rings in experiments now running at /approximately/80% of the yield strength should take 200 to 225 d to break. 21 refs., 24 figs., 5 tabs

  11. The SPI-1-like Type III secretion system: more roles than you think

    Science.gov (United States)

    Egan, Frank; Barret, Matthieu; O’Gara, Fergal

    2014-01-01

    The type III secretion system (T3SS) is a protein delivery system which is involved in a wide spectrum of interactions, from mutualism to pathogenesis, between Gram negative bacteria and various eukaryotes, including plants, fungi, protozoa and mammals. Various phylogenetic families of the T3SS have been described, including the Salmonella Pathogenicity Island 1 family (SPI-1). The SPI-1 T3SS was initially associated with the virulence of enteric pathogens, but is actually found in a diverse array of bacterial species, where it can play roles in processes as different as symbiotic interactions with insects and colonization of plants. We review the multiple roles of the SPI-1 T3SS and discuss both how these discoveries are changing our perception of the SPI-1 family and what impacts this has on our understanding of the specialization of the T3SS in general. PMID:24575107

  12. The SPI-1-like Type III secretion system: more roles than you think.

    Science.gov (United States)

    Egan, Frank; Barret, Matthieu; O'Gara, Fergal

    2014-01-01

    The type III secretion system (T3SS) is a protein delivery system which is involved in a wide spectrum of interactions, from mutualism to pathogenesis, between Gram negative bacteria and various eukaryotes, including plants, fungi, protozoa and mammals. Various phylogenetic families of the T3SS have been described, including the Salmonella Pathogenicity Island 1 family (SPI-1). The SPI-1 T3SS was initially associated with the virulence of enteric pathogens, but is actually found in a diverse array of bacterial species, where it can play roles in processes as different as symbiotic interactions with insects and colonization of plants. We review the multiple roles of the SPI-1 T3SS and discuss both how these discoveries are changing our perception of the SPI-1 family and what impacts this has on our understanding of the specialization of the T3SS in general.

  13. Mycobacterial secretion systems ESX-1 and ESX-5 play distinct roles in host cell death and inflammasome activation

    KAUST Repository

    Abdallah, Abdallah

    2011-09-28

    During infection of humans and animals, pathogenic mycobacteria manipulate the host cell causing severe diseases such as tuberculosis and leprosy. To understand the basis of mycobacterial pathogenicity, it is crucial to identify the molecular virulence mechanisms. In this study, we address the contribution of ESX-1 and ESX-5 - two homologous type VII secretion systems of mycobacteria that secrete distinct sets of immune modulators - during the macrophage infection cycle. Using wild-type, ESX-1- and ESX-5-deficient mycobacterial strains, we demonstrate that these secretion systems differentially affect subcellular localization and macrophage cell responses. We show that in contrast to ESX-1, the effector proteins secreted by ESX-5 are not required for the translocation of Mycobacterium tuberculosis or Mycobacterium marinum to the cytosol of host cells. However, the M. marinum ESX-5 mutant does not induce inflammasome activation and IL-1b activation. The ESX-5 system also induces a caspase-independent cell death after translocation has taken place. Importantly, by means of inhibitory agents and small interfering RNA experiments, we reveal that cathepsin B is involved in both the induction of cell death and inflammasome activation upon infection with wild-type mycobacteria. These results reveal distinct roles for two different type VII secretion systems during infection and shed light on how virulent mycobacteria manipulate the host cell in various ways to replicate and spread. Copyright © 2011 by The American Association of Immunologists, Inc.

  14. Characterization of Type Three Secretion System Translocator Interactions with Phospholipid Membranes.

    Science.gov (United States)

    Adam, Philip R; Barta, Michael L; Dickenson, Nicholas E

    2017-01-01

    In vitro characterization of type III secretion system (T3SS) translocator proteins has proven challenging due to complex purification schemes and their hydrophobic nature that often requires detergents to provide protein solubility and stability. Here, we provide experimental details for several techniques that overcome these hurdles, allowing for the direct characterization of the Shigella translocator protein IpaB with respect to phospholipid membrane interaction. The techniques specifically discussed in this chapter include membrane interaction/liposome flotation, liposome sensitive fluorescence quenching, and protein-mediated liposome disruption assays. These assays have provided valuable insight into the role of IpaB in T3SS-mediated phospholipid membrane interactions by Shigella and should readily extend to other members of this important class of proteins.

  15. DNA Delivery and Genomic Integration into Mammalian Target Cells through Type IV A and B Secretion Systems of Human Pathogens

    Directory of Open Access Journals (Sweden)

    Dolores L. Guzmán-Herrador

    2017-08-01

    Full Text Available We explore the potential of bacterial secretion systems as tools for genomic modification of human cells. We previously showed that foreign DNA can be introduced into human cells through the Type IV A secretion system of the human pathogen Bartonella henselae. Moreover, the DNA is delivered covalently attached to the conjugative relaxase TrwC, which promotes its integration into the recipient genome. In this work, we report that this tool can be adapted to other target cells by using different relaxases and secretion systems. The promiscuous relaxase MobA from plasmid RSF1010 can be used to deliver DNA into human cells with higher efficiency than TrwC. MobA also promotes DNA integration, albeit at lower rates than TrwC. Notably, we report that DNA transfer to human cells can also take place through the Type IV secretion system of two intracellular human pathogens, Legionella pneumophila and Coxiella burnetii, which code for a distantly related Dot/Icm Type IV B secretion system. This suggests that DNA transfer could be an intrinsic ability of this family of secretion systems, expanding the range of target human cells. Further analysis of the DNA transfer process showed that recruitment of MobA by Dot/Icm was dependent on the IcmSW chaperone, which may explain the higher DNA transfer rates obtained. Finally, we observed that the presence of MobA negatively affected the intracellular replication of C. burnetii, suggesting an interference with Dot/Icm translocation of virulence factors.

  16. Detergent Isolation Stabilizes and Activates the Shigella Type III Secretion System Translocator Protein IpaC.

    Science.gov (United States)

    Bernard, Abram R; Duarte, Shari M; Kumar, Prashant; Dickenson, Nicholas E

    2016-07-01

    Shigella rely on a type III secretion system as the primary virulence factor for invasion and colonization of human hosts. Although there are an estimated 90 million Shigella infections, annually responsible for more than 100,000 deaths worldwide, challenges isolating and stabilizing many type III secretion system proteins have prevented a full understanding of the Shigella invasion mechanism and additionally slowed progress toward a much needed Shigella vaccine. Here, we show that the non-denaturing zwitterionic detergent N, N-dimethyldodecylamine N-oxide (LDAO) and non-ionic detergent n-octyl-oligo-oxyethylene efficiently isolated the hydrophobic Shigella translocator protein IpaC from the co-purified IpaC/IpgC chaperone-bound complex. Both detergents resulted in monomeric IpaC that exhibits strong membrane binding and lysis characteristics while the chaperone-bound complex does not, suggesting that the stabilizing detergents provide a means of following IpaC "activation" in vitro. Additionally, biophysical characterization found that LDAO provides significant thermal and temporal stability to IpaC, protecting it for several days at room temperature and brief exposure to temperatures reaching 90°C. In summary, this work identified and characterized conditions that provide stable, membrane active IpaC, providing insight into key interactions with membranes and laying a strong foundation for future vaccine formulation studies taking advantage of the native immunogenicity of IpaC and the stability provided by LDAO. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  17. Gene Expression of Type VI Secretion System Associated with Environmental Survival in Acidovorax avenae subsp. avenae by Principle Component Analysis

    OpenAIRE

    Cui, Zhouqi; Jin, Guoqiang; Li, Bin; Kakar, Kaleem; Ojaghian, Mohammad; Wang, Yangli; Xie, Guanlin; Sun, Guochang

    2015-01-01

    Valine glycine repeat G (VgrG) proteins are regarded as one of two effectors of Type VI secretion system (T6SS) which is a complex multi-component secretion system. In this study, potential biological roles of T6SS structural and VgrG genes in a rice bacterial pathogen, Acidovorax avenae subsp. avenae (Aaa) RS-1, were evaluated under seven stress conditions using principle component analysis of gene expression. The results showed that growth of the pathogen was reduced by H2O2 and paraquat-i...

  18. The role of intrinsic disorder and dynamics in the assembly and function of the type II secretion system.

    Science.gov (United States)

    Gu, Shuang; Shevchik, Vladimir E; Shaw, Rosie; Pickersgill, Richard W; Garnett, James A

    2017-10-01

    Many Gram-negative commensal and pathogenic bacteria use a type II secretion system (T2SS) to transport proteins out of the cell. These exported proteins or substrates play a major role in toxin delivery, maintaining biofilms, replication in the host and subversion of host immune responses to infection. We review the current structural and functional work on this system and argue that intrinsically disordered regions and protein dynamics are central for assembly, exo-protein recognition, and secretion competence of the T2SS. The central role of intrinsic disorder-order transitions in these processes may be a particular feature of type II secretion. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Modulation of innate immune responses by Yersinia type III secretion system translocators and effectors.

    Science.gov (United States)

    Bliska, James B; Wang, Xiaoying; Viboud, Gloria I; Brodsky, Igor E

    2013-10-01

    The innate immune system of mammals responds to microbial infection through detection of conserved molecular determinants called 'pathogen-associated molecular patterns' (PAMPs). Pathogens use virulence factors to counteract PAMP-directed responses. The innate immune system can in turn recognize signals generated by virulence factors, allowing for a heightened response to dangerous pathogens. Many Gram-negative bacterial pathogens encode type III secretion systems (T3SSs) that translocate effector proteins, subvert PAMP-directed responses and are critical for infection. A plasmid-encoded T3SS in the human-pathogenic Yersinia species translocates seven effectors into infected host cells. Delivery of effectors by the T3SS requires plasma membrane insertion of two translocators, which are thought to form a channel called a translocon. Studies of the Yersinia T3SS have provided key advances in our understanding of how innate immune responses are generated by perturbations in plasma membrane and other signals that result from translocon insertion. Additionally, studies in this system revealed that effectors function to inhibit innateimmune responses resulting from insertion of translocons into plasma membrane. Here, we review these advances with the goal of providing insight into how a T3SS can activate and inhibit innate immune responses, allowing a virulent pathogen to bypass host defences. © 2013 John Wiley & Sons Ltd.

  20. Constitutive type VI secretion system expression gives Vibrio cholerae intra- and interspecific competitive advantages.

    Directory of Open Access Journals (Sweden)

    Daniel Unterweger

    Full Text Available The type VI secretion system (T6SS mediates protein translocation across the cell membrane of Gram-negative bacteria, including Vibrio cholerae - the causative agent of cholera. All V. cholerae strains examined to date harbor gene clusters encoding a T6SS. Structural similarity and sequence homology between components of the T6SS and the T4 bacteriophage cell-puncturing device suggest that the T6SS functions as a contractile molecular syringe to inject effector molecules into prokaryotic and eukaryotic target cells. Regulation of the T6SS is critical. A subset of V. cholerae strains, including the clinical O37 serogroup strain V52, express T6SS constitutively. In contrast, pandemic strains impose tight control that can be genetically disrupted: mutations in the quorum sensing gene luxO and the newly described regulator gene tsrA lead to constitutive T6SS expression in the El Tor strain C6706. In this report, we examined environmental V. cholerae isolates from the Rio Grande with regard to T6SS regulation. Rough V. cholerae lacking O-antigen carried a nonsense mutation in the gene encoding the global T6SS regulator VasH and did not display virulent behavior towards Escherichia coli and other environmental bacteria. In contrast, smooth V. cholerae strains engaged constitutively in type VI-mediated secretion and displayed virulence towards prokaryotes (E. coli and other environmental bacteria and a eukaryote (the social amoeba Dictyostelium discoideum. Furthermore, smooth V. cholerae strains were able to outcompete each other in a T6SS-dependent manner. The work presented here suggests that constitutive T6SS expression provides V. cholerae with an advantage in intraspecific and interspecific competition.

  1. Inhibition of a type III secretion system by the deletion of a short loop in one of its membrane proteins

    Energy Technology Data Exchange (ETDEWEB)

    Meshcheryakov, Vladimir A. [Okinawa Instiute of Science and Technology, Okinawa 904-0495 (Japan); Kitao, Akio [University of Tokyo, Tokyo 113-0032 (Japan); Core Research for Evolutionary Science and Technology, Tokyo 113-0032 (Japan); Matsunami, Hideyuki; Samatey, Fadel A., E-mail: f.a.samatey@oist.jp [Okinawa Instiute of Science and Technology, Okinawa 904-0495 (Japan)

    2013-05-01

    Crystal structures of the cytoplasmic domain of FlhB from S. typhimurium and A. aeolicus were solved at 2.45 and 2.55 Å resolution, respectively. The deletion of a short loop in the cytoplasmic domain of Salmonella FlhB completely abolishes secretion by the type III secretion system. A molecular-dynamics simulation shows that the deletion of the loop affects the flexibility of a linker between the transmembrane and cytoplasmic domains of FlhB. The membrane protein FlhB is a highly conserved component of the flagellar secretion system. It is composed of an N-terminal transmembrane domain and a C-terminal cytoplasmic domain (FlhB{sub C}). Here, the crystal structures of FlhB{sub C} from Salmonella typhimurium and Aquifex aeolicus are described at 2.45 and 2.55 Å resolution, respectively. These flagellar FlhB{sub C} structures are similar to those of paralogues from the needle type III secretion system, with the major difference being in a linker that connects the transmembrane and cytoplasmic domains of FlhB. It was found that deletion of a short flexible loop in a globular part of Salmonella FlhB{sub C} leads to complete inhibition of secretion by the flagellar secretion system. Molecular-dynamics calculations demonstrate that the linker region is the most flexible part of FlhB{sub C} and that the deletion of the loop reduces this flexibility. These results are in good agreement with previous studies showing the importance of the linker in the function of FlhB and provide new insight into the relationship between the different parts of the FlhB{sub C} molecule.

  2. A reduced, yet functional, nectary disk integrates a complex system of floral nectar secretion in the genus Zeyheria (Bignoniaceae

    Directory of Open Access Journals (Sweden)

    Silvia Rodrigues Machado

    Full Text Available ABSTRACT The genus Zeyheria (Bignoniaceae comprises only two species, both of which have been described as possessing a reduced and non-functional nectary disk. Despite the importance of this evolutionary change in the floral nectary, these functional assumptions have been based on disk size and on the distribution, abundance and histochemistry of corolla-borne trichomes. By combining methods on light and electron microscopy, here we investigated the functionality of the reduced nectary disk and describe all of the tissues and structures of the nectar chamber in order to determine the sites of floral nectar secretion in both Zeyheria species. . Our data find the floral nectary traits of both species to be very similar, although differing in their cellular contents. Subcellular evidence in both species indicated that disk, stipe and petal axils were, predominantly, involved in hydrophilic secretion, while capitate glandular trichomes produced lipophilic secretion and papillae produced mixed secretion. Our study shows that in spite of its reduced size, the reduced disk functions in nectar secretion in both species of Zeyheria. This kind of nectary system is a novelty for Bignoniaceae, since it comprises several tissues and structures functioning in an integrated fashion.

  3. Structure of EspB from the ESX-1 type VII secretion system and insights into its export mechanism.

    Science.gov (United States)

    Solomonson, Matthew; Setiaputra, Dheva; Makepeace, Karl A T; Lameignere, Emilie; Petrotchenko, Evgeniy V; Conrady, Deborah G; Bergeron, Julien R; Vuckovic, Marija; DiMaio, Frank; Borchers, Christoph H; Yip, Calvin K; Strynadka, Natalie C J

    2015-03-03

    Mycobacterium tuberculosis (Mtb) uses the ESX-1 type VII secretion system to export virulence proteins across its lipid-rich cell wall, which helps permeabilize the host's macrophage phagosomal membrane, facilitating the escape and cell-to-cell spread of Mtb. ESX-1 membranolytic activity depends on a set of specialized secreted Esp proteins, the structure and specific roles of which are not currently understood. Here, we report the X-ray and electron microscopic structures of the ESX-1-secreted EspB. We demonstrate that EspB adopts a PE/PPE-like fold that mediates oligomerization with apparent heptameric symmetry, generating a barrel-shaped structure with a central pore that we propose contributes to the macrophage killing functions of EspB. Our structural data also reveal unexpected direct interactions between the EspB bipartite secretion signal sequence elements that form a unified aromatic surface. These findings provide insight into how specialized proteins encoded within the ESX-1 locus are targeted for secretion, and for the first time indicate an oligomerization-dependent role for Esp virulence factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. System of matrix metalloproteinases and cytokine secretion in type 2 diabetes mellitus and impaired carbohydrate tolerance associated with arterial hypertension.

    Science.gov (United States)

    Kologrivova, I V; Suslova, T E; Koshel'skaya, O A; Vinnitskaya, I V; Trubacheva, O A

    2014-03-01

    The study included patients with type 2 diabetes mellitus and impaired carbohydrate tolerance associated with arterial hypertension, patients with arterial hypertension, and healthy volunteers. We evaluated the levels of matrix metalloproteinases 2 and 9 (MMP-2, MMP-9), tissue inhibitor of metalloproteinase type 1 (TIMP-1), glucose, insulin, C-peptide, glycated hemoglobin, and spontaneous and mitogen-activated cytokine secretion (IL-2, IL4, IL-6, IL-10, IL-17, TNF-α, and IFN-γ). Patients with type 2 diabetes mellitus in combination with arterial hypertension exhibited maximum TIMP-1 levels and TIMP-1/MMP-2, TIMP-1/ MMP-9 ratios as well as enhanced secretion of TNF-α, IL-6, IL-17 and reduced secretion of IL-10 in comparison with healthy individuals. The observed shifts are probably determined the development of systemic hyperinsulinemia in patients suffering from type 2 diabetes mellitus coupled with arterial hypertension.

  5. Near-atomic resolution analysis of BipD, a component of the type III secretion system of Burkholderia pseudomallei

    International Nuclear Information System (INIS)

    Pal, M.; Erskine, P. T.; Gill, R. S.; Wood, S. P.; Cooper, J. B.

    2010-01-01

    The type III secretion system needle-tip protein BipD has been crystallized in a form that diffracts X-rays to 1.5 Å resolution and the structure has been refined to an R factor of 16.1% and an R free of 19.8% at this resolution. The putative antiparallel dimer interface that was observed in earlier structures is conserved. Burkholderia pseudomallei, the causative agent of melioidosis, possesses a type III protein secretion apparatus that is similar to those found in Salmonella and Shigella. A major function of these secretion systems is to inject virulence-associated proteins into target cells of the host organism. The bipD gene of B. pseudomallei encodes a secreted virulence factor that is similar in sequence and is most likely to be functionally analogous to IpaD from Shigella and SipD from Salmonella. Proteins in this family are thought to act as extracellular chaperones at the tip of the secretion needle to help the hydrophobic translocator proteins enter the target cell membrane, where they form a pore and may also link the translocon pore with the secretion needle. BipD has been crystallized in a monoclinic crystal form that diffracted X-rays to 1.5 Å resolution and the structure was refined to an R factor of 16.1% and an R free of 19.8% at this resolution. The putative dimer interface that was observed in previous crystal structures was retained and a larger surface area was buried in the new crystal form

  6. Authentication Without Secrets

    Energy Technology Data Exchange (ETDEWEB)

    Pierson, Lyndon G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robertson, Perry J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    This work examines a new approach to authentication, which is the most fundamental security primitive that underpins all cyber security protections. Current Internet authentication techniques require the protection of one or more secret keys along with the integrity protection of the algorithms/computations designed to prove possession of the secret without actually revealing it. Protecting a secret requires physical barriers or encryption with yet another secret key. The reason to strive for "Authentication without Secret Keys" is that protecting secrets (even small ones only kept in a small corner of a component or device) is much harder than protecting the integrity of information that is not secret. Promising methods are examined for authentication of components, data, programs, network transactions, and/or individuals. The successful development of authentication without secret keys will enable far more tractable system security engineering for high exposure, high consequence systems by eliminating the need for brittle protection mechanisms to protect secret keys (such as are now protected in smart cards, etc.). This paper is a re-release of SAND2009-7032 with new figures numerous edits.

  7. Type VI secretion system MIX-effectors carry both antibacterial and anti-eukaryotic activities.

    Science.gov (United States)

    Ray, Ann; Schwartz, Nika; de Souza Santos, Marcela; Zhang, Junmei; Orth, Kim; Salomon, Dor

    2017-11-01

    Most type VI secretion systems (T6SSs) described to date are protein delivery apparatuses that mediate bactericidal activities. Several T6SSs were also reported to mediate virulence activities, although only few anti-eukaryotic effectors have been described. Here, we identify three T6SSs in the marine bacterium Vibrio proteolyticus and show that T6SS1 mediates bactericidal activities under warm marine-like conditions. Using comparative proteomics, we find nine potential T6SS1 effectors, five of which belong to the polymorphic MIX-effector class. Remarkably, in addition to six predicted bactericidal effectors, the T6SS1 secretome includes three putative anti-eukaryotic effectors. One of these is a MIX-effector containing a cytotoxic necrotizing factor 1 domain. We demonstrate that T6SS1 can use this MIX-effector to target phagocytic cells, resulting in morphological changes and actin cytoskeleton rearrangements. In conclusion, the V. proteolyticus T6SS1, a system homologous to one found in pathogenic vibrios, uses a suite of polymorphic effectors that target both bacteria and eukaryotic neighbors. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  8. Vibrio tapetis Displays an Original Type IV Secretion System in Strains Pathogenic for Bivalve Molluscs

    Directory of Open Access Journals (Sweden)

    Graciela M. Dias

    2018-02-01

    Full Text Available The Brown Ring Disease (BRD caused high mortality rates since 1986 in the Manila clam Venerupis philippinarum introduced and cultured in Western Europe from the 1970s. The causative agent of BRD is a Gram-Negative bacterium, Vibrio tapetis, which is also pathogenic to fish. Here we report the first assembly of the complete genome of V. tapetis CECT4600T, together with the genome sequences of 16 additional strains isolated across a broad host and geographic range. Our extensive genome dataset allowed us to describe the pathogen pan- and core genomes and to identify putative virulence factors. The V. tapetis core genome consists of 3,352 genes, including multiple potential virulence factors represented by haemolysins, transcriptional regulators, Type I restriction modification system, GGDEF domain proteins, several conjugative plasmids, and a Type IV secretion system. Future research on the coevolutionary arms race between V. tapetis virulence factors and host resistance mechanisms will improve our understanding of how pathogenicity develops in this emerging pathogen.

  9. A Cryptographic SoC for Robust Protection of Secret Keys in IPTV DRM Systems

    Science.gov (United States)

    Lee, Sanghan; Yang, Hae-Yong; Yeom, Yongjin; Park, Jongsik

    The security level of an internet protocol television (IPTV) digital right management (DRM) system ultimately relies on protection of secret keys. Well known devices for the key protection include smartcards and battery backup SRAMs (BB-SRAMs); however, these devices could be vulnerable to various physical attacks. In this paper, we propose a secure and cost-effective design of a cryptographic system on chip (SoC) that integrates the BB-SRAM with a cell-based design technique. The proposed SoC provides robust safeguard against the physical attacks, and satisfies high-speed and low-price requirements of IPTV set-top boxes. Our implementation results show that the maximum encryption rate of the SoC is 633Mb/s. In order to verify the data retention capabilities, we made a prototype chip using 0.18µm standard cell technology. The experimental results show that the integrated BB-SRAM can reliably retain data with a 1.4µA leakage current.

  10. The marine bacteria Shewanella frigidimarina NCIMB400 upregulates the type VI secretion system during early biofilm formation.

    Science.gov (United States)

    Linares, Denis; Jean, Natacha; Van Overtvelt, Perrine; Ouidir, Tassadit; Hardouin, Julie; Blache, Yves; Molmeret, Maëlle

    2016-02-01

    Shewanella sp. are facultative anaerobic Gram-negative bacteria, extensively studied for their electron transfer ability. Shewanella frigidimarina has been detected and isolated from marine environments, and in particular, from biofilms. However, its ability to adhere to surfaces and form a biofilm is poorly understood. In this study, we show that the ability to adhere and to form a biofilm of S. frigidimarina NCIMB400 is significantly higher than that of Shewanella oneidensis in our conditions. We also show that this strain forms a biofilm in artificial seawater, whereas in Luria-Bertani, this capacity is reduced. To identify proteins involved in early biofilm formation, a proteomic analysis of sessile versus planktonic membrane-enriched fractions allowed the identification of several components of the same type VI secretion system gene cluster: putative Hcp1 and ImpB proteins as well as a forkhead-associated domain-containing protein. The upregulation of Hcp1 a marker of active translocation has been confirmed using quantitative reverse transcription polymerase chain reaction. Our data demonstrated the presence of a single and complete type VI secretion system in S. frigidimarina NCIMB400 genome, upregulated in sessile compared with planktonic conditions. The fact that three proteins including the secreted protein Hcp1 have been identified may suggest that this type VI secretion system is functional. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Effective cancer vaccine platform based on attenuated salmonella and a type III secretion system.

    Science.gov (United States)

    Xu, Xin; Hegazy, Wael A H; Guo, Linjie; Gao, Xiuhua; Courtney, Amy N; Kurbanov, Suhrab; Liu, Daofeng; Tian, Gengwen; Manuel, Edwin R; Diamond, Don J; Hensel, Michael; Metelitsa, Leonid S

    2014-11-01

    Vaccines explored for cancer therapy have been based generally on injectable vector systems used to control foreign infectious pathogens, to which the immune system evolved to respond naturally. However, these vectors may not be effective at presenting tumor-associated antigens (TAA) to the immune system in a manner that is sufficient to engender antitumor responses. We addressed this issue with a novel orally administered Salmonella-based vector that exploits a type III secretion system to deliver selected TAA in the cytosol of professional antigen-presenting cells in situ. A systematic comparison of candidate genes from the Salmonella Pathogenicity Island 2 (SPI2) locus was conducted in the vaccine design, using model antigens and a codon-optimized form of the human TAA survivin (coSVN), an oncoprotein that is overexpressed in most human cancers. In a screen of 20 SPI2 promoter:effector combinations, a PsifB::sseJ combination exhibited maximal potency for antigen translocation into the APC cytosol, presentation to CD8 T cells, and murine immunogenicity. In the CT26 mouse model of colon carcinoma, therapeutic vaccination with a lead PsifB::sseJ-coSVN construct (p8032) produced CXCR3-dependent infiltration of tumors by CD8 T cells, reversed the CD8:Treg ratio at the tumor site, and triggered potent antitumor activity. Vaccine immunogenicity and antitumor potency were enhanced by coadministration of the natural killer T-cell ligand 7DW8-5, which heightened the production of IL12 and IFNγ. Furthermore, combined treatment with p8032 and 7DW8-5 resulted in complete tumor regression in A20 lymphoma-bearing mice, where protective memory was demonstrated. Taken together, our results demonstrate how antigen delivery using an oral Salmonella vector can provide an effective platform for the development of cancer vaccines. ©2014 American Association for Cancer Research.

  12. Nasal secretions from patients with polyps and healthy individuals, collected with a new aspiration system: evaluation of total protein and immunoglobulin concentrations

    NARCIS (Netherlands)

    Biewenga, J.; Stoop, A. E.; Baker, H. E.; Swart, S. J.; Nauta, J. J.; van Kamp, G. J.; van der Baan, S.

    1991-01-01

    This study was designed, first, to test a new system for aspiration of human nasal secretions and, secondly, to evaluate protein and immunoglobulin concentrations in these secretions at different levels of secretory activity. The direct aspiration system combines the advantages of minimal irritation

  13. Structure of the type IV secretion system in different strains of Anaplasma phagocytophilum

    Directory of Open Access Journals (Sweden)

    Al-Khedery Basima

    2012-11-01

    Full Text Available Abstract Background Anaplasma phagocytophilum is an intracellular organism in the Order Rickettsiales that infects diverse animal species and is causing an emerging disease in humans, dogs and horses. Different strains have very different cell tropisms and virulence. For example, in the U.S., strains have been described that infect ruminants but not dogs or rodents. An intriguing question is how the strains of A. phagocytophilum differ and what different genome loci are involved in cell tropisms and/or virulence. Type IV secretion systems (T4SS are responsible for translocation of substrates across the cell membrane by mechanisms that require contact with the recipient cell. They are especially important in organisms such as the Rickettsiales which require T4SS to aid colonization and survival within both mammalian and tick vector cells. We determined the structure of the T4SS in 7 strains from the U.S. and Europe and revised the sequence of the repetitive virB6 locus of the human HZ strain. Results Although in all strains the T4SS conforms to the previously described split loci for vir genes, there is great diversity within these loci among strains. This is particularly evident in the virB2 and virB6 which are postulated to encode the secretion channel and proteins exposed on the bacterial surface. VirB6-4 has an unusual highly repetitive structure and can have a molecular weight greater than 500,000. For many of the virs, phylogenetic trees position A. phagocytophilum strains infecting ruminants in the U.S. and Europe distant from strains infecting humans and dogs in the U.S. Conclusions Our study reveals evidence of gene duplication and considerable diversity of T4SS components in strains infecting different animals. The diversity in virB2 is in both the total number of copies, which varied from 8 to 15 in the herein characterized strains, and in the sequence of each copy. The diversity in virB6 is in the sequence of each of the 4 copies in

  14. Bile salt receptor complex activates a pathogenic type III secretion system

    Science.gov (United States)

    Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N; Salomon, Dor; Tomchick, Diana R; Grishin, Nick V; Orth, Kim

    2016-01-01

    Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure of VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment. DOI: http://dx.doi.org/10.7554/eLife.15718.001 PMID:27377244

  15. Bile salt receptor complex activates a pathogenic type III secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N.; Salomon, Dor; Tomchick, Diana R.; Grishin, Nick V.; Orth, Kim

    2016-07-05

    Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered thatVibrio parahaemolyticusVtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure of VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment.

  16. Cell individuality: the bistable gene expression of the type III secretion system in Dickeya dadantii 3937.

    Science.gov (United States)

    Zeng, Quan; Laiosa, Michael D; Steeber, Douglas A; Biddle, Eulandria M; Peng, Quan; Yang, Ching-Hong

    2012-01-01

    Dickeya dadantii 3937 is a gram-negative phytopathogenic bacterium that expresses genes encoding a type III secretion system (T3SS) in a bistable pattern when cultured in a homogeneous minimal media. In this work, we further characterized the bistable gene expression of T3SS at the single-cell level. We demonstrated that bistable expression of the HrpL-regulon genes, such as hrpA and hrpN, is controlled by the same regulatory mechanism. We also showed that the expression level of the T3SS master regulatory gene hrpL plays an important role in the development of the bistable expression of hrpA. A high expression level of hrpL is required but unable to guarantee the high-state expression of hrpA in a cell. In addition, bistable expression patterns of T3SS genes in other gram-negative pathogens of the Enterobacteriaceae and Pseudomonadaceae families were also described in this study. This suggests that the T3SS bistability might be a conserved population behavior in several gram-negative bacterial pathogens.

  17. The type VI secretion system impacts bacterial invasion and population dynamics in a model intestinal microbiota

    Science.gov (United States)

    Logan, Savannah L.; Shields, Drew S.; Hammer, Brian K.; Xavier, Joao B.; Parthasarathy, Raghuveer

    Animal gastrointestinal tracts are home to a diverse community of microbes. The mechanisms by which microbial species interact and compete in this dense, physically dynamic space are poorly understood, limiting our understanding of how natural communities are assembled and how different communities could be engineered. Here, we focus on a physical mechanism for competition: the type VI secretion system (T6SS). The T6SS is a syringe-like organelle used by certain bacteria to translocate effector proteins across the cell membranes of target bacterial cells, killing them. Here, we use T6SS+ and T6SS- strains of V. cholerae, the pathogen that causes cholera in humans, and light sheet fluorescence microscopy for in vivo imaging to show that the T6SS provides an advantage to strains colonizing the larval zebrafish gut. Furthermore, we show that T6SS+ bacteria can invade and alter an existing population of a different species in the zebrafish gut, reducing its abundance and changing the form of its population dynamics. This work both demonstrates a mechanism for altering the gut microbiota with an invasive species and explores the processes controlling the stability and dynamics of the gut ecosystem. Research Corporation, Gordon and Betty Moore Foundation, and the Simons Foundation.

  18. Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly

    Directory of Open Access Journals (Sweden)

    Amy J. Gerc

    2015-09-01

    Full Text Available The Type VI secretion system (T6SS is a bacterial nanomachine that fires toxic proteins into target cells. Deployment of the T6SS represents an efficient and widespread means by which bacteria attack competitors or interact with host organisms and may be triggered by contact from an attacking neighbor cell as a defensive strategy. Here, we use the opportunist pathogen Serratia marcescens and functional fluorescent fusions of key components of the T6SS to observe different subassemblies of the machinery simultaneously and on multiple timescales in vivo. We report that the localization and dynamic behavior of each of the components examined is distinct, revealing a multi-stage and dynamic assembly process for the T6SS machinery. We also show that the T6SS can assemble and fire without needing a cell contact trigger, defining an aggressive strategy that broadens target range and suggesting that activation of the T6SS is tailored to survival in specific niches.

  19. Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly

    Science.gov (United States)

    Gerc, Amy J.; Diepold, Andreas; Trunk, Katharina; Porter, Michael; Rickman, Colin; Armitage, Judith P.; Stanley-Wall, Nicola R.; Coulthurst, Sarah J.

    2015-01-01

    Summary The Type VI secretion system (T6SS) is a bacterial nanomachine that fires toxic proteins into target cells. Deployment of the T6SS represents an efficient and widespread means by which bacteria attack competitors or interact with host organisms and may be triggered by contact from an attacking neighbor cell as a defensive strategy. Here, we use the opportunist pathogen Serratia marcescens and functional fluorescent fusions of key components of the T6SS to observe different subassemblies of the machinery simultaneously and on multiple timescales in vivo. We report that the localization and dynamic behavior of each of the components examined is distinct, revealing a multi-stage and dynamic assembly process for the T6SS machinery. We also show that the T6SS can assemble and fire without needing a cell contact trigger, defining an aggressive strategy that broadens target range and suggesting that activation of the T6SS is tailored to survival in specific niches. PMID:26387948

  20. A Phosphorylation Switch on Lon Protease Regulates Bacterial Type III Secretion System in Host

    Directory of Open Access Journals (Sweden)

    Xiaofeng Zhou

    2018-01-01

    Full Text Available Most pathogenic bacteria deliver virulence factors into host cytosol through type III secretion systems (T3SS to perturb host immune responses. The expression of T3SS is often repressed in rich medium but is specifically induced in the host environment. The molecular mechanisms underlying host-specific induction of T3SS expression is not completely understood. Here we demonstrate in Xanthomonas citri that host-induced phosphorylation of the ATP-dependent protease Lon stabilizes HrpG, the master regulator of T3SS, conferring bacterial virulence. Ser/Thr/Tyr phosphoproteome analysis revealed that phosphorylation of Lon at serine 654 occurs in the citrus host. In rich medium, Lon represses T3SS by degradation of HrpG via recognition of its N terminus. Genetic and biochemical data indicate that phosphorylation at serine 654 deactivates Lon proteolytic activity and attenuates HrpG proteolysis. Substitution of alanine for Lon serine 654 resulted in repression of T3SS gene expression in the citrus host through robust degradation of HrpG and reduced bacterial virulence. Our work reveals a novel mechanism for distinct regulation of bacterial T3SS in different environments. Additionally, our data provide new insight into the role of protein posttranslational modification in the regulation of bacterial virulence.

  1. Secreted autoantibody repertoires in Sjögren's syndrome and systemic lupus erythematosus: A proteomic approach.

    Science.gov (United States)

    Al Kindi, Mahmood A; Colella, Alex D; Chataway, Tim K; Jackson, Michael W; Wang, Jing J; Gordon, Tom P

    2016-04-01

    The structures of epitopes bound by autoantibodies against RNA-protein complexes have been well-defined over several decades, but little is known of the clonality, immunoglobulin (Ig) variable (V) gene usage and mutational status of the autoantibodies themselves at the level of the secreted (serum) proteome. A novel proteomic workflow is presented based on affinity purification of specific Igs from serum, high-resolution two-dimensional gel electrophoresis, and de novo and database-driven sequencing of V-region proteins by mass spectrometry. Analysis of anti-Ro52/Ro60/La proteomes in primary Sjögren's syndrome (SS) and anti-Sm and anti-ribosomal P proteomes in systemic lupus erythematosus (SLE) has revealed that these antibody responses are dominated by restricted sets of public (shared) clonotypes, consistent with common pathways of production across unrelated individuals. The discovery of shared sets of specific V-region peptides can be exploited for diagnostic biomarkers in targeted mass spectrometry platforms and for tracking and removal of pathogenic clones. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Porphyromonas gingivalis and related bacteria: from colonial pigmentation to the type IX secretion system and gliding motility

    Science.gov (United States)

    Nakayama, K

    2015-01-01

    Porphyromonas gingivalis is a gram-negative, non-motile, anaerobic bacterium implicated as a major pathogen in periodontal disease. P. gingivalis grows as black-pigmented colonies on blood agar, and many bacteriologists have shown interest in this property. Studies of colonial pigmentation have revealed a number of important findings, including an association with the highly active extracellular and surface proteinases called gingipains that are found in P. gingivalis. The Por secretion system, a novel type IX secretion system (T9SS), has been implicated in gingipain secretion in studies using non-pigmented mutants. In addition, many potent virulence proteins, including the metallocarboxypeptidase CPG70, 35 kDa hemin-binding protein HBP35, peptidylarginine deiminase PAD and Lys-specific serine endopeptidase PepK, are secreted through the T9SS. These findings have not been limited to P. gingivalis but have been extended to other bacteria belonging to the phylum Bacteroidetes. Many Bacteroidetes species possess the T9SS, which is associated with gliding motility for some of these bacteria. PMID:25546073

  3. N-acyl-L-homoserine lactone-mediated regulation of the Lip secretion system in Serratia liquefaciens MG1

    DEFF Research Database (Denmark)

    Riedel, K.; Ohnesorg, T.; Krogfelt, K.A.

    2001-01-01

    The analysis of Serratia liquefaciens MG1 'luxAB insertion mutants that are responsive to N-butanoyl-L-homoserine lactone revealed that expression of lipB is controlled by the swr quorum-sensing system. LipB is part of the Lip exporter, a type I secretion system, which is responsible for the secr......The analysis of Serratia liquefaciens MG1 'luxAB insertion mutants that are responsive to N-butanoyl-L-homoserine lactone revealed that expression of lipB is controlled by the swr quorum-sensing system. LipB is part of the Lip exporter, a type I secretion system, which is responsible...

  4. Manganese scavenging and oxidative stress response mediated by type VI secretion system in Burkholderia thailandensis.

    Science.gov (United States)

    Si, Meiru; Zhao, Chao; Burkinshaw, Brianne; Zhang, Bing; Wei, Dawei; Wang, Yao; Dong, Tao G; Shen, Xihui

    2017-03-14

    Type VI secretion system (T6SS) is a versatile protein export machinery widely distributed in Gram-negative bacteria. Known to translocate protein substrates to eukaryotic and prokaryotic target cells to cause cellular damage, the T6SS has been primarily recognized as a contact-dependent bacterial weapon for microbe-host and microbial interspecies competition. Here we report contact-independent functions of the T6SS for metal acquisition, bacteria competition, and resistance to oxidative stress. We demonstrate that the T6SS-4 in Burkholderia thailandensis is critical for survival under oxidative stress and is regulated by OxyR, a conserved oxidative stress regulator. The T6SS-4 is important for intracellular accumulation of manganese (Mn 2+ ) under oxidative stress. Next, we identified a T6SS-4-dependent Mn 2+ -binding effector TseM, and its interacting partner MnoT, a Mn 2+ -specific TonB-dependent outer membrane transporter. Similar to the T6SS-4 genes, expression of mnoT is regulated by OxyR and is induced under oxidative stress and low Mn 2+ conditions. Both TseM and MnoT are required for efficient uptake of Mn 2+ across the outer membrane under Mn 2+ -limited and -oxidative stress conditions. The TseM-MnoT-mediated active Mn 2+ transport system is also involved in contact-independent bacteria-bacteria competition and bacterial virulence. This finding provides a perspective for understanding the mechanisms of metal ion uptake and the roles of T6SS in bacteria-bacteria competition.

  5. Global transcriptional profiling of Burkholderia pseudomallei under salt stress reveals differential effects on the Bsa type III secretion system

    Directory of Open Access Journals (Sweden)

    Singsuksawat Ekapot

    2010-06-01

    Full Text Available Abstract Background Burkholderia pseudomallei is the causative agent of melioidosis where the highest reported incidence world wide is in the Northeast of Thailand, where saline soil and water are prevalent. Moreover, recent reports indicate a potential pathogenic role for B. pseudomallei in cystic fibrosis lung disease, where an increased sodium chloride (NaCl concentration in airway surface liquid has been proposed. These observations raise the possibility that high salinity may represent a favorable niche for B. pseudomallei. We therefore investigated the global transcriptional response of B. pseudomallei to increased salinity using microarray analysis. Results Transcriptome analysis of B. pseudomallei under salt stress revealed several genes significantly up-regulated in the presence of 320 mM NaCl including genes associated with the bsa-derived Type III secretion system (T3SS. Microarray data were verified by reverse transcriptase-polymerase chain reactions (RT-PCR. Western blot analysis confirmed the increased expression and secretion of the invasion-associated type III secreted proteins BipD and BopE in B. pseudomallei cultures at 170 and 320 mM NaCl relative to salt-free medium. Furthermore, salt-treated B. pseudomallei exhibited greater invasion efficiency into the lung epithelial cell line A549 in a manner partly dependent on a functional Bsa system. Conclusions B. pseudomallei responds to salt stress by modulating the transcription of a relatively small set of genes, among which is the bsa locus associated with invasion and virulence. Expression and secretion of Bsa-secreted proteins was elevated in the presence of exogenous salt and the invasion efficiency was enhanced. Our data indicate that salinity has the potential to influence the virulence of B. pseudomallei.

  6. Diversification of Type VI Secretion System Toxins Reveals Ancient Antagonism among Bee Gut Microbes

    Directory of Open Access Journals (Sweden)

    Margaret I. Steele

    2017-12-01

    Full Text Available Microbial communities are shaped by interactions among their constituent members. Some Gram-negative bacteria employ type VI secretion systems (T6SSs to inject protein toxins into neighboring cells. These interactions have been theorized to affect the composition of host-associated microbiomes, but the role of T6SSs in the evolution of gut communities is not well understood. We report the discovery of two T6SSs and numerous T6SS-associated Rhs toxins within the gut bacteria of honey bees and bumble bees. We sequenced the genomes of 28 strains of Snodgrassella alvi, a characteristic bee gut microbe, and found tremendous variability in their Rhs toxin complements: altogether, these strains appear to encode hundreds of unique toxins. Some toxins are shared with Gilliamella apicola, a coresident gut symbiont, implicating horizontal gene transfer as a source of toxin diversity in the bee gut. We use data from a transposon mutagenesis screen to identify toxins with antibacterial function in the bee gut and validate the function and specificity of a subset of these toxin and immunity genes in Escherichia coli. Using transcriptome sequencing, we demonstrate that S. alvi T6SSs and associated toxins are upregulated in the gut environment. We find that S. alvi Rhs loci have a conserved architecture, consistent with the C-terminal displacement model of toxin diversification, with Rhs toxins, toxin fragments, and cognate immunity genes that are expressed and confer strong fitness effects in vivo. Our findings of T6SS activity and Rhs toxin diversity suggest that T6SS-mediated competition may be an important driver of coevolution within the bee gut microbiota.

  7. The Trw type IV secretion system of Bartonella mediates host-specific adhesion to erythrocytes.

    Directory of Open Access Journals (Sweden)

    Muriel Vayssier-Taussat

    2010-06-01

    Full Text Available Bacterial pathogens typically infect only a limited range of hosts; however, the genetic mechanisms governing host-specificity are poorly understood. The alpha-proteobacterial genus Bartonella comprises 21 species that cause host-specific intraerythrocytic bacteremia as hallmark of infection in their respective mammalian reservoirs, including the human-specific pathogens Bartonella quintana and Bartonella bacilliformis that cause trench fever and Oroya fever, respectively. Here, we have identified bacterial factors that mediate host-specific erythrocyte colonization in the mammalian reservoirs. Using mouse-specific Bartonella birtlesii, human-specific Bartonella quintana, cat-specific Bartonella henselae and rat-specific Bartonella tribocorum, we established in vitro adhesion and invasion assays with isolated erythrocytes that fully reproduce the host-specificity of erythrocyte infection as observed in vivo. By signature-tagged mutagenesis of B. birtlesii and mutant selection in a mouse infection model we identified mutants impaired in establishing intraerythrocytic bacteremia. Among 45 abacteremic mutants, five failed to adhere to and invade mouse erythrocytes in vitro. The corresponding genes encode components of the type IV secretion system (T4SS Trw, demonstrating that this virulence factor laterally acquired by the Bartonella lineage is directly involved in adherence to erythrocytes. Strikingly, ectopic expression of Trw of rat-specific B. tribocorum in cat-specific B. henselae or human-specific B. quintana expanded their host range for erythrocyte infection to rat, demonstrating that Trw mediates host-specific erythrocyte infection. A molecular evolutionary analysis of the trw locus further indicated that the variable, surface-located TrwL and TrwJ might represent the T4SS components that determine host-specificity of erythrocyte parasitism. In conclusion, we show that the laterally acquired Trw T4SS diversified in the Bartonella lineage

  8. The Type III Secretion System-Related CPn0809 from Chlamydia pneumoniae.

    Directory of Open Access Journals (Sweden)

    Astrid C Engel

    Full Text Available Chlamydia pneumoniae is an intracellular Gram-negative bacterium that possesses a type III secretion system (T3SS, which enables the pathogen to deliver, in a single step, effector proteins for modulation of host-cell functions into the human host cell cytosol to establish a unique intracellular niche for replication. The translocon proteins located at the top of the T3SS needle filament are essential for its function, as they form pores in the host-cell membrane. Interestingly, unlike other Gram-negative bacteria, C. pneumoniae has two putative translocon operons, named LcrH_1 and LcrH_2. However, little is known about chlamydial translocon proteins. In this study, we analyzed CPn0809, one of the putative hydrophobic translocators encoded by the LcrH_1 operon, and identified an 'SseC-like family' domain characteristic of T3S translocators. Using bright-field and confocal microscopy, we found that CPn0809 is associated with EBs during early and very late phases of a C. pneumoniae infection. Furthermore, CPn0809 forms oligomers, and interacts with the T3SS chaperone LcrH_1, via its N-terminal segment. Moreover, expression of full-length CPn0809 in the heterologous host Escherichia coli causes a grave cytotoxic effect that leads to cell death. Taken together, our data indicate that CPn0809 likely represents one of the translocon proteins of the C. pneumoniae T3SS, and possibly plays a role in the translocation of effector proteins in the early stages of infection.

  9. Semisynthesis of SY-1 for investigation of breast cancer stem cell selectivity of C-ring-modified salinomycin analogues.

    Science.gov (United States)

    Huang, Xiaoli; Borgström, Björn; Månsson, Linda; Persson, Lo; Oredsson, Stina; Hegardt, Cecilia; Strand, Daniel

    2014-07-18

    Salinomycin, a naturally occurring polyether ionophore was recently found to selectively reduce the proportion of CD44(+)/CD24(-) cells, a phenotype associated with breast cancer stem cells. Subsequent studies from our group showed that chemical modification of the allylic C20 hydroxyl of salinomycin, located at the C-ring, can enhance the activity of derivatives against breast cancer cells over 5-fold compared to the native structure. Access to C-ring-modified salinomycin analogues is thus of interest from both a mechanistic and a synthetic perspective. Here, we report efficient strategies for gram scale synthesis of the natural product SY-1 (20-deoxy salinomycin), and a saturated analogue, 18,19-dihydro SY-1, for a comparative in vitro investigation of the biological profiles of these compounds with that of salinomycin. Across several assays, the deoxygenated structures required higher concentrations to elicit similar cellular responses to that of salinomycin. Similarly to salinomycin, SY-1 or 18,19-dihydro SY-1 treatment was found to reduce the proportion of CD44(+)/CD24(-) cells with essentially complete selectivity up to ∼IC25. Importantly, the proportion of CD44(+)/CD24(-) cells showed a pronounced U-shaped dose response curve for salinomycin and its derivatives, but not for paclitaxel. The concentration for maximum response in this assay followed differences in IC50 for salinomycin and its analogues, which emphasizes the importance of taking concentration dependence into account when comparing effects on the CD44(+)/CD24(-) phenotype. Small differences in the global conformation within the triad of compounds investigated together with differences in activity across assays emphasize the importance of substitution at C20 for the activity of salinomycin and its derivatives.

  10. In vitro expression of Sec-dependent pathway and type 4B secretion system in Piscirickettsia salmonis.

    Science.gov (United States)

    Cortés, Marcos; Sánchez, Patricio; Ruiz, Pamela; Haro, Ronie; Sáez, Jerson; Sánchez, Fabián; Hernández, Mauricio; Oliver, Cristian; Yáñez, Alejandro J

    2017-09-01

    Piscirickettsia salmonis is an intracellular bacterium and the causative agent of Piscirickettsiosis, a disease responsible for considerable mortalities in the Chilean salmon farming industry. Currently, P. salmonis protein translocation across the membrane and the mechanisms by which virulence factors are delivered to host cells are poorly understood. However, it is known that Gram-negative bacteria possess several mechanisms that transport proteins to the periplasmic and extracellular compartments. The aim of this study was to evaluate the expressional changes of several genes in the P. salmonis Sec-dependent pathway and type 4B secretion system during in vitro infection. Genes homologous and the main proteins belonging to Sec-dependent pathway and Type 4 Dot/Icm secretion system were found in the genome and proteome of P. salmonis AUSTRAL-005 strain. Additionally, several genes of these protein transport mechanisms were overexpressed during in vitro P. salmonis infection in SHK-1 cell line. The obtained data indicate that the Sec-dependent pathway and Type 4B secretion system are biologically active during P. salmonis infection. These mechanisms could contribute to the recycling of proteins into the inner and outer bacterial membrane and in translocate virulence factors to infected cell, which would favor the structural integrity and virulence of this bacterium. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Topology of a type I secretion system for bacteriocins of Lactococcus lactis

    NARCIS (Netherlands)

    Franke, Christian Marc

    1998-01-01

    This thesis describes the analysis of a number of aspects of the secretion and muturation machinery of the bacteriocin lactococcin A (LcnA) from Lactococcus lactis, whick is initially synthesized as a precursor protein (preLcnA), containing an N-terminal extension of 20 amino acids (the leader)....

  12. Computational prediction of secretion systems and secretomes of Brucella: identification of novel type IV effectors and their interaction with the host.

    Science.gov (United States)

    Sankarasubramanian, Jagadesan; Vishnu, Udayakumar S; Dinakaran, Vasudevan; Sridhar, Jayavel; Gunasekaran, Paramasamy; Rajendhran, Jeyaprakash

    2016-01-01

    Brucella spp. are facultative intracellular pathogens that cause brucellosis in various mammals including humans. Brucella survive inside the host cells by forming vacuoles and subverting host defence systems. This study was aimed to predict the secretion systems and the secretomes of Brucella spp. from 39 complete genome sequences available in the databases. Furthermore, an attempt was made to identify the type IV secretion effectors and their interactions with host proteins. We predicted the secretion systems of Brucella by the KEGG pathway and SecReT4. Brucella secretomes and type IV effectors (T4SEs) were predicted through genome-wide screening using JVirGel and S4TE, respectively. Protein-protein interactions of Brucella T4SEs with their hosts were analyzed by HPIDB 2.0. Genes coding for Sec and Tat pathways of secretion and type I (T1SS), type IV (T4SS) and type V (T5SS) secretion systems were identified and they are conserved in all the species of Brucella. In addition to the well-known VirB operon coding for the type IV secretion system (T4SS), we have identified the presence of additional genes showing homology with T4SS of other organisms. On the whole, 10.26 to 14.94% of total proteomes were found to be either secreted (secretome) or membrane associated (membrane proteome). Approximately, 1.7 to 3.0% of total proteomes were identified as type IV secretion effectors (T4SEs). Prediction of protein-protein interactions showed 29 and 36 host-pathogen specific interactions between Bos taurus (cattle)-B. abortus and Ovis aries (sheep)-B. melitensis, respectively. Functional characterization of the predicted T4SEs and their interactions with their respective hosts may reveal the secrets of host specificity of Brucella.

  13. Evidence for alternative quaternary structure in a bacterial Type III secretion system chaperone

    Energy Technology Data Exchange (ETDEWEB)

    Barta, Michael L.; Zhang, Lingling; Picking, Wendy L.; Geisbrecht, Brian V. (UMKC); (OKLU)

    2010-10-05

    Type III secretion systems are a common virulence mechanism in many Gram-negative bacterial pathogens. These systems use a nanomachine resembling a molecular needle and syringe to provide an energized conduit for the translocation of effector proteins from the bacterial cytoplasm to the host cell cytoplasm for the benefit of the pathogen. Prior to translocation specialized chaperones maintain proper effector protein conformation. The class II chaperone, Invasion plasmid gene (Ipg) C, stabilizes two pore forming translocator proteins. IpgC exists as a functional dimer to facilitate the mutually exclusive binding of both translocators. In this study, we present the 3.3 {angstrom} crystal structure of an amino-terminally truncated form (residues 10-155, denoted IpgC10-155) of the class II chaperone IpgC from Shigella flexneri. Our structure demonstrates an alternative quaternary arrangement to that previously described for a carboxy-terminally truncated variant of IpgC (IpgC{sup 1-151}). Specifically, we observe a rotationally-symmetric 'head-to-head' dimerization interface that is far more similar to that previously described for SycD from Yersinia enterocolitica than to IpgC1-151. The IpgC structure presented here displays major differences in the amino terminal region, where extended coil-like structures are seen, as opposed to the short, ordered alpha helices and asymmetric dimerization interface seen within IpgC{sup 1-151}. Despite these differences, however, both modes of dimerization support chaperone activity, as judged by a copurification assay with a recombinant form of the translocator protein, IpaB. Conclusions: From primary to quaternary structure, these results presented here suggest that a symmetric dimerization interface is conserved across bacterial class II chaperones. In light of previous data which have described the structure and function of asymmetric dimerization, our results raise the possibility that class II chaperones may

  14. The type III secretion system is involved in the invasion and intracellular survival of Escherichia coli K1 in human brain microvascular endothelial cells

    OpenAIRE

    Yao, Yufeng; Xie, Yi; Perace, Donna; Zhong, Yi; Lu, Jie; Tao, Jing; Guo, Xiaokui; Kim, Kwang Sik

    2009-01-01

    Type III secretion systems have been documented in many Gram-negative bacteria, including enterohemorrhagic Escherichia coli. We have previously shown the existence of a putative type III secretion system in meningitis-causing E. coli K1 strains, referred to as E. coli type III secretion 2 (ETT2). The sequence of ETT2 in meningitis-causing E. coli K1 strain EC10 (O7:K1) revealed that ETT2 comprises the epr, epa and eiv genes, but bears mutations, deletions and insertions. We constructed the E...

  15. Identification of the Vibrio parahaemolyticus type III secretion system 2-associated chaperone VocC for the T3SS2-specific effector VopC.

    Science.gov (United States)

    Akeda, Yukihiro; Kodama, Toshio; Saito, Kazunobu; Iida, Tetsuya; Oishi, Kazunori; Honda, Takeshi

    2011-11-01

    The enteropathogen Vibrio parahaemolyticus possesses two sets of type III secretion systems, T3SS1 and T3SS2. Effector proteins secreted by these T3SSs are delivered into host cells, leading to cell death or diarrhea. However, it is not known how specific effectors are secreted through a specific T3SS when both T3SSs are expressed within bacteria. One molecule thought to determine secretion specificity is a T3SS-associated chaperone; however, no T3SS2-specific chaperone has been identified. Therefore, we screened T3SS2 chaperone candidates by a pull-down assay using T3SS2 effectors fused with glutathione-S-transferase. A secretion assay revealed that the newly identified cognate chaperone VocC for the T3SS2-specific effector VopC was required for the efficient secretion of the substrate through T3SS2. Further experiments determined the chaperone-binding domain and the amino-terminal secretion signal of the cognate effector. These findings, in addition to the previously identified T3SS1-specific chaperone, VecA, provide a strategy to clarify the specificity of effector secretion through T3SSs of V. parahaemolyticus. 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  16. Comparative transcriptomics with a motility-deficient mutant leads to identification of a novel polysaccharide secretion system in Nostoc punctiforme.

    Science.gov (United States)

    Risser, Douglas D; Meeks, John C

    2013-02-01

    Many filamentous cyanobacteria are capable of gliding motility by an undefined mechanism. Within the heterocyst-forming clades, some strains, such as the Nostoc spp. and Fisherella spp., are motile only as specialized filaments termed hormogonia. Here we report on the phenotype of inactivation of a methyl-accepting chemotaxis-like protein in Nostoc punctiforme, designated HmpD. The gene hmpD was found to be essential for hormogonium development, motility and polysaccharide secretion. Comparative global transcriptional profiling of the ΔhmpD strain demonstrated that HmpD has a profound effect on the transcriptional programme of hormogonium development, influencing approximately half of the genes differentially transcribed during differentiation. Utilizing this transcriptomic data, we identified a gene locus, designated here as hps, that appears to encode for a novel polysaccharide secretion system. Transcripts for the genes in the hps locus are upregulated in two steps, with the second step dependent on HmpD. Deletion of hpsA, hpsBCD or hpsEFG resulted in the complete loss of motility and polysaccharide secretion, similar to deletion of hmpD. Genes in the hps locus are highly conserved in the filamentous cyanobacteria, but generally absent in unicellular strains, implying a common mechanism of motility unique to the filamentous cyanobacteria. © 2012 Blackwell Publishing Ltd.

  17. [Do lactoferrin, lysozyme and the lactoperoxidase-thiocyanate-hydrogen peroxide-system cause negative microbiological results in mastitis secretions?].

    Science.gov (United States)

    Schmedt Auf Der Günne, H; Tenhagen, B A; Kutzer, P; Forderung, D; Heuwieser, W

    2002-07-01

    Lactoferrin, lysozyme and the lactoperoxidase-thiocyanate-peroxide-system are naturally occurring antimicrobial components of milk. The objective of this study was to examine, whether these components were responsible for negative results, when mastitis milk is cultured microbiologically. Quarter milk samples from 75 cows with clinical mastitis on a dairy farm in Brandenburg were submitted for microbiological culture and analysed for the content and the activities of the three components. Animals from all stages of lactation with clinical mastitis were included in the study. Animals were examined clinically and milk samples were collected prior to first treatment. Secretions from quarters with clinical mastitis were compared to those of neighbouring quarters without clinical mastitis. Secretions with positive cultural results were compared to those with negative results. The concentrations or activities of the three factors were significantly higher in the diseased quarters than in the quarters without clinical signs of mastitis. The concentration of lysozyme increased with severity of the clinical signs (local swelling and changes in secretion). The concentration of lactoferrin was significantly higher in quarters with slight alterations of glandular tissue than in quarters with medium or severe alterations (P mastitis with positive and negative culture results. The concentration of lysozyme was even higher in culturally positive samples than in negative samples (P culture of milk samples from quarters with clinical mastitis.

  18. Spa47 is an oligomerization-activated type three secretion system (T3SS) ATPase from Shigella flexneri.

    Science.gov (United States)

    Burgess, Jamie L; Jones, Heather B; Kumar, Prashant; Toth, Ronald T; Middaugh, C Russell; Antony, Edwin; Dickenson, Nicholas E

    2016-05-01

    Gram-negative pathogens often use conserved type three secretion systems (T3SS) for virulence. The Shigella type three secretion apparatus (T3SA) penetrates the host cell membrane and provides a unidirectional conduit for injection of effectors into host cells. The protein Spa47 localizes to the base of the apparatus and is speculated to be an ATPase that provides the energy for T3SA formation and secretion. Here, we developed an expression and purification protocol, producing active Spa47 and providing the first direct evidence that Spa47 is a bona fide ATPase. Additionally, size exclusion chromatography and analytical ultracentrifugation identified multiple oligomeric species of Spa47 with the largest greater than 8 fold more active for ATP hydrolysis than the monomer. An ATPase inactive Spa47 point mutant was then engineered by targeting a conserved Lysine within the predicted Walker A motif of Spa47. Interestingly, the mutant maintained a similar oligomerization pattern as active Spa47, but was unable to restore invasion phenotype when used to complement a spa47 null S. flexneri strain. Together, these results identify Spa47 as a Shigella T3SS ATPase and suggest that its activity is linked to oligomerization, perhaps as a regulatory mechanism as seen in some related pathogens. Additionally, Spa47 catalyzed ATP hydrolysis appears to be essential for host cell invasion, providing a strong platform for additional studies dissecting its role in virulence and providing an attractive target for anti-infective agents. © 2016 The Protein Society.

  19. Dynamic secrets in communication security

    CERN Document Server

    Xiao, Sheng; Towsley, Donald

    2013-01-01

    Dynamic secrets are constantly generated and updated from messages exchanged between two communication users. When dynamic secrets are used as a complement to existing secure communication systems, a stolen key or password can be quickly and automatically reverted to its secret status without disrupting communication. 'Dynamic Secrets in Communication Security' presents unique security properties and application studies for this technology. Password theft and key theft no longer pose serious security threats when parties frequently use dynamic secrets. This book also illustrates that a dynamic

  20. A yeast-based model system for cloning secreted and membrane proteins

    Directory of Open Access Journals (Sweden)

    MARCELO J. SURPILI

    2002-12-01

    Full Text Available The targeting of proteins to cell organelles and membranes, or of proteins destined to secretion, is coordinated by signal sequences located at the 5´-end of their respective genes. A signal sequence trap system was envisaged in which a truncated version of the yeast acid phosphatase pho5 gene lacking the start codon and signal sequence could serve as a reporter gene. A fraction enriched in 5´-end fragments obtained by PCR from a potato guard-cell cDNA library was cloned in frame to the acid phosphatase gene and the acid phosphatase activity was assayed directly in yeast colonies grown on selective medium. Putative signal sequences targeting the acid phosphatase to the membrane or to the outside of the cell were used to screen the cDNA bank in order to recover the original full-size sequence which gave rise to the signal sequence. Two unknown sequences displaying marked tissue-specific expression were retrieved, one of them (YE139 with a higher expression level in green buds and stem cells, and the other one (YE290 with a higher expression level in androceum, gyneceum, and roots. The limitations of the system are further analyzed using other sequences as control.O direcionamento de proteínas a organelas e à membrana celular, ou de proteínas a serem secretadas, é coordenado por seqüências sinalizadoras localizadas na extremidade 5´ de seus respectivos genes que codificam peptídeos-sinal. Este trabalho analisa um sistema para seleção de seqüências sinalizadoras utilizando uma fosfatase ácida de levedura, enzima reconhecidamente secretada por estes organismos, desprovida de seu códon de iniciação e de sua seqüência sinalizadora, como gene repórter. Uma fração enriquecida em fragmentos provenientes da região 5´ de uma biblioteca de cDNA de células-guarda de batata foi inserida in frame ao gene truncado da fosfatase ácida em vetores apropriados. Após a transformação em leveduras, a atividade da fosfatase ácida foi

  1. Identification of small-molecule inhibitors of Yersinia pestis Type III secretion system YscN ATPase.

    Directory of Open Access Journals (Sweden)

    Wieslaw Swietnicki

    Full Text Available Yersinia pestis is a gram negative zoonotic pathogen responsible for causing bubonic and pneumonic plague in humans. The pathogen uses a type III secretion system (T3SS to deliver virulence factors directly from bacterium into host mammalian cells. The system contains a single ATPase, YscN, necessary for delivery of virulence factors. In this work, we show that deletion of the catalytic domain of the yscN gene in Y. pestis CO92 attenuated the strain over three million-fold in the Swiss-Webster mouse model of bubonic plague. The result validates the YscN protein as a therapeutic target for plague. The catalytic domain of the YscN protein was made using recombinant methods and its ATPase activity was characterized in vitro. To identify candidate therapeutics, we tested computationally selected small molecules for inhibition of YscN ATPase activity. The best inhibitors had measured IC(50 values below 20 µM in an in vitro ATPase assay and were also found to inhibit the homologous BsaS protein from Burkholderia mallei animal-like T3SS at similar concentrations. Moreover, the compounds fully inhibited YopE secretion by attenuated Y. pestis in a bacterial cell culture and mammalian cells at µM concentrations. The data demonstrate the feasibility of targeting and inhibiting a critical protein transport ATPase of a bacterial virulence system. It is likely the same strategy could be applied to many other common human pathogens using type III secretion system, including enteropathogenic E. coli, Shigella flexneri, Salmonella typhimurium, and Burkholderia mallei/pseudomallei species.

  2. Identification of small-molecule inhibitors of Yersinia pestis Type III secretion system YscN ATPase.

    Science.gov (United States)

    Swietnicki, Wieslaw; Carmany, Daniel; Retford, Michael; Guelta, Mark; Dorsey, Russell; Bozue, Joel; Lee, Michael S; Olson, Mark A

    2011-01-01

    Yersinia pestis is a gram negative zoonotic pathogen responsible for causing bubonic and pneumonic plague in humans. The pathogen uses a type III secretion system (T3SS) to deliver virulence factors directly from bacterium into host mammalian cells. The system contains a single ATPase, YscN, necessary for delivery of virulence factors. In this work, we show that deletion of the catalytic domain of the yscN gene in Y. pestis CO92 attenuated the strain over three million-fold in the Swiss-Webster mouse model of bubonic plague. The result validates the YscN protein as a therapeutic target for plague. The catalytic domain of the YscN protein was made using recombinant methods and its ATPase activity was characterized in vitro. To identify candidate therapeutics, we tested computationally selected small molecules for inhibition of YscN ATPase activity. The best inhibitors had measured IC(50) values below 20 µM in an in vitro ATPase assay and were also found to inhibit the homologous BsaS protein from Burkholderia mallei animal-like T3SS at similar concentrations. Moreover, the compounds fully inhibited YopE secretion by attenuated Y. pestis in a bacterial cell culture and mammalian cells at µM concentrations. The data demonstrate the feasibility of targeting and inhibiting a critical protein transport ATPase of a bacterial virulence system. It is likely the same strategy could be applied to many other common human pathogens using type III secretion system, including enteropathogenic E. coli, Shigella flexneri, Salmonella typhimurium, and Burkholderia mallei/pseudomallei species.

  3. The structure of Serratia marcescens Lip, a membrane-bound component of the type VI secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Vincenzo A.; Shepherd, Sharon M.; English, Grant; Coulthurst, Sarah J.; Hunter, William N., E-mail: w.n.hunter@dundee.ac.uk [College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland (United Kingdom)

    2011-12-01

    The high-resolution crystal structure of S. marcescens Lip reveals a new member of the transthyretin family of proteins. Lip, a core component of the type VI secretion apparatus, is localized to the outer membrane and is positioned to interact with other proteins forming this complex system. Lip is a membrane-bound lipoprotein and a core component of the type VI secretion system found in Gram-negative bacteria. The structure of a Lip construct (residues 29–176) from Serratia marcescens (SmLip) has been determined at 1.92 Å resolution. Experimental phases were derived using a single-wavelength anomalous dispersion approach on a sample cocrystallized with iodide. The membrane localization of the native protein was confirmed. The structure is that of the globular domain lacking only the lipoprotein signal peptide and the lipidated N-terminus of the mature protein. The protein fold is dominated by an eight-stranded β-sandwich and identifies SmLip as a new member of the transthyretin family of proteins. Transthyretin and the only other member of the family fold, 5-hydroxyisourate hydrolase, form homotetramers important for their function. The asymmetric unit of SmLip is a tetramer with 222 symmetry, but the assembly is distinct from that previously noted for the transthyretin protein family. However, structural comparisons and bacterial two-hybrid data suggest that the SmLip tetramer is not relevant to its role as a core component of the type VI secretion system, but rather reflects a propensity for SmLip to participate in protein–protein interactions. A relatively low level of sequence conservation amongst Lip homologues is noted and is restricted to parts of the structure that might be involved in interactions with physiological partners.

  4. The structure of Serratia marcescens Lip, a membrane-bound component of the type VI secretion system

    International Nuclear Information System (INIS)

    Rao, Vincenzo A.; Shepherd, Sharon M.; English, Grant; Coulthurst, Sarah J.; Hunter, William N.

    2011-01-01

    The high-resolution crystal structure of S. marcescens Lip reveals a new member of the transthyretin family of proteins. Lip, a core component of the type VI secretion apparatus, is localized to the outer membrane and is positioned to interact with other proteins forming this complex system. Lip is a membrane-bound lipoprotein and a core component of the type VI secretion system found in Gram-negative bacteria. The structure of a Lip construct (residues 29–176) from Serratia marcescens (SmLip) has been determined at 1.92 Å resolution. Experimental phases were derived using a single-wavelength anomalous dispersion approach on a sample cocrystallized with iodide. The membrane localization of the native protein was confirmed. The structure is that of the globular domain lacking only the lipoprotein signal peptide and the lipidated N-terminus of the mature protein. The protein fold is dominated by an eight-stranded β-sandwich and identifies SmLip as a new member of the transthyretin family of proteins. Transthyretin and the only other member of the family fold, 5-hydroxyisourate hydrolase, form homotetramers important for their function. The asymmetric unit of SmLip is a tetramer with 222 symmetry, but the assembly is distinct from that previously noted for the transthyretin protein family. However, structural comparisons and bacterial two-hybrid data suggest that the SmLip tetramer is not relevant to its role as a core component of the type VI secretion system, but rather reflects a propensity for SmLip to participate in protein–protein interactions. A relatively low level of sequence conservation amongst Lip homologues is noted and is restricted to parts of the structure that might be involved in interactions with physiological partners

  5. Type IX secretion system PorM and gliding machinery GldM form arches spanning the periplasmic space

    OpenAIRE

    Leone, Philippe; Roche, Jennifer; Vincent, Maxence S.; Tran, Quang Hieu; Desmyter, Aline; Cascales, Eric; Kellenberger, Christine; Cambillau, Christian; Roussel, Alain

    2018-01-01

    Type IX secretion system (T9SS), exclusively present in the Bacteroidetes phylum, has been studied mainly in Flavobacterium johnsoniae and Porphyromonas gingivalis. Among the 18 genes, essential for T9SS function, a group of four, porK-N (P. gingivalis) or gldK-N (F. johnsoniae) belongs to a co-transcribed operon that expresses the T9SS core membrane complex. The central component of this complex, PorM (or GldM), is anchored in the inner membrane by a trans-membrane helix and interacts throug...

  6. The Type IX Secretion System (T9SS): Highlights and Recent Insights into Its Structure and Function

    Science.gov (United States)

    Lasica, Anna M.; Ksiazek, Miroslaw; Madej, Mariusz; Potempa, Jan

    2017-01-01

    Protein secretion systems are vital for prokaryotic life, as they enable bacteria to acquire nutrients, communicate with other species, defend against biological and chemical agents, and facilitate disease through the delivery of virulence factors. In this review, we will focus on the recently discovered type IX secretion system (T9SS), a complex translocon found only in some species of the Bacteroidetes phylum. T9SS plays two roles, depending on the lifestyle of the bacteria. It provides either a means of movement (called gliding motility) for peace-loving environmental bacteria or a weapon for pathogens. The best-studied members of these two groups are Flavobacterium johnsoniae, a commensal microorganism often found in water and soil, and Porphyromonas gingivalis, a human oral pathogen that is a major causative agent of periodontitis. In P. gingivalis and some other periodontopathogens, T9SS translocates proteins, especially virulence factors, across the outer membrane (OM). Proteins destined for secretion bear a conserved C-terminal domain (CTD) that directs the cargo to the OM translocon. At least 18 proteins are involved in this still enigmatic process, with some engaged in the post-translational modification of T9SS cargo proteins. Upon translocation across the OM, the CTD is removed by a protease with sortase-like activity and an anionic LPS is attached to the newly formed C-terminus. As a result, a cargo protein could be secreted into the extracellular milieu or covalently attached to the bacterial surface. T9SS is regulated by a two-component system; however, the precise environmental signal that triggers it has not been identified. Exploring unknown systems contributing to bacterial virulence is exciting, as it may eventually lead to new therapeutic strategies. During the past decade, the major components of T9SS were identified, as well as hints suggesting the possible mechanism of action. In addition, the list of characterized cargo proteins is

  7. The Type IX Secretion System (T9SS: Highlights and Recent Insights into Its Structure and Function

    Directory of Open Access Journals (Sweden)

    Anna M. Lasica

    2017-05-01

    Full Text Available Protein secretion systems are vital for prokaryotic life, as they enable bacteria to acquire nutrients, communicate with other species, defend against biological and chemical agents, and facilitate disease through the delivery of virulence factors. In this review, we will focus on the recently discovered type IX secretion system (T9SS, a complex translocon found only in some species of the Bacteroidetes phylum. T9SS plays two roles, depending on the lifestyle of the bacteria. It provides either a means of movement (called gliding motility for peace-loving environmental bacteria or a weapon for pathogens. The best-studied members of these two groups are Flavobacterium johnsoniae, a commensal microorganism often found in water and soil, and Porphyromonas gingivalis, a human oral pathogen that is a major causative agent of periodontitis. In P. gingivalis and some other periodontopathogens, T9SS translocates proteins, especially virulence factors, across the outer membrane (OM. Proteins destined for secretion bear a conserved C-terminal domain (CTD that directs the cargo to the OM translocon. At least 18 proteins are involved in this still enigmatic process, with some engaged in the post-translational modification of T9SS cargo proteins. Upon translocation across the OM, the CTD is removed by a protease with sortase-like activity and an anionic LPS is attached to the newly formed C-terminus. As a result, a cargo protein could be secreted into the extracellular milieu or covalently attached to the bacterial surface. T9SS is regulated by a two-component system; however, the precise environmental signal that triggers it has not been identified. Exploring unknown systems contributing to bacterial virulence is exciting, as it may eventually lead to new therapeutic strategies. During the past decade, the major components of T9SS were identified, as well as hints suggesting the possible mechanism of action. In addition, the list of characterized cargo

  8. Secret Places.

    Science.gov (United States)

    Ridolfi, Kerry

    1997-01-01

    Argues that children are as deep as the ocean, with secret places inside of them waiting to be opened. Notes that it is powerful for students to learn they can make sense of the world through words, and describes inviting them into poetry as they read poetry, create poetry packets, and write and revise poems. (SR)

  9. Water deprivation affects serotoninergic system and glycoprotein secretion in the sub-commissural organ of a desert rodent Meriones shawi.

    Science.gov (United States)

    Elgot, Abdeljalil; Ahboucha, Samir; Bouyatas, My Mustapha; Fèvre-Montange, Michèlle; Gamrani, Halima

    2009-11-27

    Water deprivation is a stress that has been associated with activation of several endocrine systems, including circumventricular organs of the central nervous system. The sub-comissural organ (SCO), characterized by its glycoprotein secretion called Reissner's fiber has been suggested to play a role in the regulation of body water balance. Meriones shawi, a semi-desertic rodent characterized by its resistance to long periods of thirst was subjected to water deprivation for 1 and 3 months. Effect of water deprivation was evaluated immunohistochemically on 5-hydroxytryptamine (5-HT; serotonin) system and glycoprotein secretion of the SCO. Our findings demonstrate significant reduction of anti-Reissner's fiber immunoreactive materials within basal and apical parts of the SCO ependymocytes. These changes seem to be the consequence of reduced control by 5-HT fibers reaching the SCO as a concomitant and significant reduction of anti-5-HT immunoreactive fibers are also observed following water deprivation. 5-HT immunoreactive reduction is seen in several regions in the brain including the neurons of origin within the dorsal raphe nucleus and the projecting supra and sub-ependymal fibers reaching the classical ependyma of the third ventricle. The extent of Reissner's fiber and 5-HT immunoreactive changes significantly correlates with the severity of water restriction. We suggest that water deprivation causes changes of the classical ependyma and the specialized ependyma that differentiates into the SCO as well as other cirumventricular organs such as the subfornical organ and the organum vasculosum laminae terminalis known to control drinking behaviors.

  10. The Type VI Secretion System Engages a Redox-Regulated Dual-Functional Heme Transporter for Zinc Acquisition.

    Science.gov (United States)

    Si, Meiru; Wang, Yao; Zhang, Bing; Zhao, Chao; Kang, Yiwen; Bai, Haonan; Wei, Dawei; Zhu, Lingfang; Zhang, Lei; Dong, Tao G; Shen, Xihui

    2017-07-25

    The type VI secretion system was recently reported to be involved in zinc acquisition, but the underlying mechanism remains unclear. Here, we report that Burkholderia thailandensis T6SS4 is involved in zinc acquisition via secretion of a zinc-scavenging protein, TseZ, that interacts with the outer membrane heme transporter HmuR. We find that HmuR is a redox-regulated dual-functional transporter that transports heme iron under normal conditions but zinc upon sensing extracellular oxidative stress, triggered by formation of an intramolecular disulfide bond. Acting as the first line of defense against oxidative stress, HmuR not only guarantees an immediate response to the changing environment but also provides a fine-tuned mechanism that allows a gradual response to perceived stress. The T6SS/HmuR-mediated active zinc transport system is also involved in bacterial virulence and contact-independent bacterial competition. We describe a sophisticated bacterial zinc acquisition mechanism affording insights into the role of metal ion transport systems. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  11. The Coxiella Burnetii type IVB secretion system (T4BSS) component DotA is released/secreted during infection of host cells and during in vitro growth in a T4BSS-dependent manner.

    Science.gov (United States)

    Luedtke, Brandon E; Mahapatra, Saugata; Lutter, Erika I; Shaw, Edward I

    2017-06-01

    Coxiella burnetii is a Gram-negative intracellular pathogen and is the causative agent of the zoonotic disease Q fever. To cause disease, C. burnetii requires a functional type IVB secretion system (T4BSS) to transfer effector proteins required for the establishment and maintenance of a membrane-bound parasitophorous vacuole (PV) and further modulation of host cell process. However, it is not clear how the T4BSS interacts with the PV membrane since neither a secretion pilus nor an extracellular pore forming apparatus has not been described. To address this, we used the acidified citrate cysteine medium (ACCM) along with cell culture infection and immunological techniques to identify the cellular and extracellular localization of T4BSS components. Interestingly, we found that DotA and IcmX were secreted/released in a T4BSS-dependent manner into the ACCM. Analysis of C. burnetii-infected cell lines revealed that DotA colocalized with the host cell marker CD63 (LAMP3) at the PV membrane. In the absence of bacterial protein synthesis, DotA also became depleted from the PV membrane. These data are the first to identify the release/secretion of C. burnetii T4BSS components during axenic growth and the interaction of a T4BSS component with the PV membrane during infection of host cells. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. The Xanthomonas Ax21 protein is processed by the general secretory system and is secreted in association with outer membrane vesicles

    Directory of Open Access Journals (Sweden)

    Ofir Bahar

    2014-01-01

    Full Text Available Pattern recognition receptors (PRRs play an important role in detecting invading pathogens and mounting a robust defense response to restrict infection. In rice, one of the best characterized PRRs is XA21, a leucine rich repeat receptor-like kinase that confers broad-spectrum resistance to multiple strains of the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo. In 2009 we reported that an Xoo protein, called Ax21, is secreted by a type I-secretion system and that it serves to activate XA21-mediated immunity. This report has recently been retracted. Here we present data that corrects our previous model. We first show that Ax21 secretion does not depend on the predicted type I secretion system and that it is processed by the general secretion (Sec system. We further show that Ax21 is an outer membrane protein, secreted in association with outer membrane vesicles. Finally, we provide data showing that ax21 knockout strains do not overcome XA21-mediated immunity.

  13. Hijacking of the pleiotropic cytokine interferon-γ by the type III secretion system of Yersinia pestis.

    Directory of Open Access Journals (Sweden)

    Claire Gendrin

    Full Text Available Yersinia pestis, the causative agent of bubonic plague, employs its type III secretion system to inject toxins into target cells, a crucial step in infection establishment. LcrV is an essential component of the T3SS of Yersinia spp, and is able to associate at the tip of the secretion needle and take part in the translocation of anti-host effector proteins into the eukaryotic cell cytoplasm. Upon cell contact, LcrV is also released into the surrounding medium where it has been shown to block the normal inflammatory response, although details of this mechanism have remained elusive. In this work, we reveal a key aspect of the immunomodulatory function of LcrV by showing that it interacts directly and with nanomolar affinity with the inflammatory cytokine IFNγ. In addition, we generate specific IFNγ mutants that show decreased interaction capabilities towards LcrV, enabling us to map the interaction region to two basic C-terminal clusters of IFNγ. Lastly, we show that the LcrV-IFNγ interaction can be disrupted by a number of inhibitors, some of which display nanomolar affinity. This study thus not only identifies novel potential inhibitors that could be developed for the control of Yersinia-induced infection, but also highlights the diversity of the strategies used by Y. pestis to evade the immune system, with the hijacking of pleiotropic cytokines being a long-range mechanism that potentially plays a key role in the severity of plague.

  14. Gene Expression of Type VI Secretion System Associated with Environmental Survival in Acidovorax avenae subsp. avenae by Principle Component Analysis

    Directory of Open Access Journals (Sweden)

    Zhouqi Cui

    2015-09-01

    Full Text Available Valine glycine repeat G (VgrG proteins are regarded as one of two effectors of Type VI secretion system (T6SS which is a complex multi-component secretion system. In this study, potential biological roles of T6SS structural and VgrG genes in a rice bacterial pathogen, Acidovorax avenae subsp. avenae (Aaa RS-1, were evaluated under seven stress conditions using principle component analysis of gene expression. The results showed that growth of the pathogen was reduced by H2O2 and paraquat-induced oxidative stress, high salt, low temperature, and vgrG mutation, compared to the control. However, pathogen growth was unaffected by co-culture with a rice rhizobacterium Burkholderia seminalis R456. In addition, expression of 14 T6SS structural and eight vgrG genes was significantly changed under seven conditions. Among different stress conditions, high salt, and low temperature showed a higher effect on the expression of T6SS gene compared with host infection and other environmental conditions. As a first report, this study revealed an association of T6SS gene expression of the pathogen with the host infection, gene mutation, and some common environmental stresses. The results of this research can increase understanding of the biological function of T6SS in this economically-important pathogen of rice.

  15. Gene Expression of Type VI Secretion System Associated with Environmental Survival in Acidovorax avenae subsp. avenae by Principle Component Analysis.

    Science.gov (United States)

    Cui, Zhouqi; Jin, Guoqiang; Li, Bin; Kakar, Kaleem Ullah; Ojaghian, Mohammad Reza; Wang, Yangli; Xie, Guanlin; Sun, Guochang

    2015-09-11

    Valine glycine repeat G (VgrG) proteins are regarded as one of two effectors of Type VI secretion system (T6SS) which is a complex multi-component secretion system. In this study, potential biological roles of T6SS structural and VgrG genes in a rice bacterial pathogen, Acidovorax avenae subsp. avenae (Aaa) RS-1, were evaluated under seven stress conditions using principle component analysis of gene expression. The results showed that growth of the pathogen was reduced by H₂O₂ and paraquat-induced oxidative stress, high salt, low temperature, and vgrG mutation, compared to the control. However, pathogen growth was unaffected by co-culture with a rice rhizobacterium Burkholderia seminalis R456. In addition, expression of 14 T6SS structural and eight vgrG genes was significantly changed under seven conditions. Among different stress conditions, high salt, and low temperature showed a higher effect on the expression of T6SS gene compared with host infection and other environmental conditions. As a first report, this study revealed an association of T6SS gene expression of the pathogen with the host infection, gene mutation, and some common environmental stresses. The results of this research can increase understanding of the biological function of T6SS in this economically-important pathogen of rice.

  16. [Participation of parasympathetic part of nervous system in realization of bioflavonoids action on gastric secretion in rats].

    Science.gov (United States)

    Vovkun, T V; Yanchuk, P I; Shtanova, L Y; Veselskyy, S P; Shalamay, A S

    2015-01-01

    In this study we investigated the effects of corvitin--modified form of flavonoid quercetin on the stomach secretory function and physiological mechanisms involved in the maintenance of such effects in rat's pylorus-ligated model. In animals which corvitin was injected at a dose of 5 mg/kg, regardless of the route of administration--in the stomach or duodenum, did not observe any changes in the volume of gastric juice or general production of hydrochloric acid, compared with the control data. Dose of 40 mg/kg caused an increase in the volume of gastric juice and hydrochloric acid output as when administered in the stomach and in the duodenum. We also found that after the application of a large dose of corvitin (intragastrically) in the blood of experimental animals showed reduction in glucose levels, which was not detected when using the drug in a dose of 5 mg/kg. Nonspecific antagonist of M-cholinergic receptors--atropine almost completely blocked the enhancement of gastric secretion, which was caused by the introduction into the stomach of corvitin in large dose. From the present data, it is reasonable to conclude that intragastric administration of a large dose of corvitin to pylorus-ligated rats induces hypoglycemic reaction of blood, which may causes an increase in vagus nerve activity with subsequent stimulation of gastric secretion. The increase in gastric juice volume and gastric acid output induced by corvitin was completely inhibited by atropine. These results suggested that the increase in gastric secretion induced by intragastrically administered corvitin could be mediated by the parasympathetic nervous system.

  17. MxiN Differentially Regulates Monomeric and Oligomeric Species of the Shigella Type Three Secretion System ATPase Spa47.

    Science.gov (United States)

    Case, Heather B; Dickenson, Nicholas E

    2018-04-17

    Shigella rely entirely on the action of a single type three secretion system (T3SS) to support cellular invasion of colonic epithelial cells and to circumvent host immune responses. The ATPase Spa47 resides at the base of the Shigella needle-like type three secretion apparatus (T3SA), supporting protein secretion through the apparatus and providing a likely means for native virulence regulation by Shigella and a much needed target for non-antibiotic therapeutics to treat Shigella infections. Here, we show that MxiN is a differential regulator of Spa47 and that its regulatory impact is determined by the oligomeric state of the Spa47 ATPase, with which it interacts. In vitro and in vivo characterization shows that interaction of MxiN with Spa47 requires the six N-terminal residues of Spa47 that are also necessary for stable Spa47 oligomer formation and activation. This interaction with MxiN negatively influences the activity of Spa47 oligomers while upregulating the ATPase activity of monomeric Spa47. Detailed kinetic analyses of monomeric and oligomeric Spa47 in the presence and absence of MxiN uncover additional mechanistic insights into the regulation of Spa47 by MxiN, suggesting that the MxiN/Spa47 species resulting from interaction with monomeric and oligomeric Spa47 are functionally distinct and that both could be involved in Shigella T3SS regulation. Uncovering regulation of Spa47 by MxiN addresses an important gap in the current understanding of how Shigella controls T3SA activity and provides the first description of differential T3SS ATPase regulation by a native T3SS protein.

  18. The Structures of Coiled-Coil Domains from Type III Secretion System Translocators Reveal Homology to Pore-Forming Toxins

    Energy Technology Data Exchange (ETDEWEB)

    Barta, Michael L.; Dickenson, Nicholas E.; Patil, Mrinalini; Keightley, Andrew; Wyckoff, Gerald J.; Picking, William D.; Picking, Wendy L.; Geisbrecht, Brian V. (UMKC); (OKLU)

    2012-03-26

    Many pathogenic Gram-negative bacteria utilize type III secretion systems (T3SSs) to alter the normal functions of target cells. Shigella flexneri uses its T3SS to invade human intestinal cells to cause bacillary dysentery (shigellosis) that is responsible for over one million deaths per year. The Shigella type III secretion apparatus is composed of a basal body spanning both bacterial membranes and an exposed oligomeric needle. Host altering effectors are secreted through this energized unidirectional conduit to promote bacterial invasion. The active needle tip complex of S. flexneri is composed of a tip protein, IpaD, and two pore-forming translocators, IpaB and IpaC. While the atomic structure of IpaD has been elucidated and studied, structural data on the hydrophobic translocators from the T3SS family remain elusive. We present here the crystal structures of a protease-stable fragment identified within the N-terminal regions of IpaB from S. flexneri and SipB from Salmonella enterica serovar Typhimurium determined at 2.1 {angstrom} and 2.8 {angstrom} limiting resolution, respectively. These newly identified domains are composed of extended-length (114 {angstrom} in IpaB and 71 {angstrom} in SipB) coiled-coil motifs that display a high degree of structural homology to one another despite the fact that they share only 21% sequence identity. Further structural comparisons also reveal substantial similarity to the coiled-coil regions of pore-forming proteins from other Gram-negative pathogens, notably, colicin Ia. This suggests that these mechanistically separate and functionally distinct membrane-targeting proteins may have diverged from a common ancestor during the course of pathogen-specific evolutionary events.

  19. RSA-Based Secret Handshakes

    OpenAIRE

    Vergnaud , Damien

    2006-01-01

    A secret handshake mechanism allows two entities, members of a same group, to authenticate each other secretly. This primitive was introduced recently by Balfanz, Durfee, Shankar, Smetters, Staddon and Wong and, so far, all the schemes proposed are based on discrete log systems. This paper proposes three new secret handshake protocols secure against active impersonator and detector adversaries. Inspired by two RSA-based key agreement protocols introduced by Okamoto and Tanaka in 1989 and Gira...

  20. Subinhibitory concentration of kanamycin induces the Pseudomonas aeruginosa type VI secretion system.

    Directory of Open Access Journals (Sweden)

    Cerith Jones

    Full Text Available Pseudomonas aeruginosa is a Gram-negative bacterium found in natural environments including plants, soils and warm moist surfaces. This organism is also in the top ten of nosocomial pathogens, and prevalent in cystic fibrosis (CF lung infections. The ability of P. aeruginosa to colonize a wide variety of environments in a lasting manner is associated with the formation of a resistant biofilm and the capacity to efficiently outcompete other microorganisms. Here we demonstrate that sub-inhibitory concentration of kanamycin not only induces biofilm formation but also induces expression of the type VI secretion genes in the H1-T6SS cluster. The H1-T6SS is known for its role in toxin production and bacterial competition. We show that the antibiotic induction of the H1-T6SS only occurs when a functional Gac/Rsm pathway is present. These observations may contribute to understand how P. aeruginosa responds to antibiotic producing competitors. It also suggests that improper antibiotic therapy may enhance P. aeruginosa colonization, including in the airways of CF patients.

  1. Transcriptional regulator GntR of Brucella abortus regulates cytotoxicity, induces the secretion of inflammatory cytokines and affects expression of the type IV secretion system and quorum sensing system in macrophages.

    Science.gov (United States)

    Li, Zhiqiang; Wang, Shuli; Zhang, Hui; Zhang, Jinliang; Xi, Li; Zhang, Junbo; Chen, Chuangfu

    2017-03-01

    The pathogenic mechanisms of Brucella are still poorly understood. GntR is a transcriptional regulator and plays an important role in the intracellular survival of Brucella. To investigate whether GntR is involved in the cytotoxicity of Brucella abortus (B. abortus), we created a 2308ΔgntR mutant of B. abortus 2308 (S2308). Lactate dehydrogenase (LDH) cytotoxicity assays using a murine macrophage cell line (RAW 264.7) show that high-dose infection with the parental strain produces a high level of cytotoxicity to macrophages, but the 2308ΔgntR mutant exhibits a very low level of cytotoxicity, indicating that mutation of GntR impairs the cytotoxicity of B. abortus to macrophages. After the macrophages are infected with 2308ΔgntR, the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) increase and are slightly higher than that for the S2308 infected group, indicating that the 2308ΔgntR mutant could induce the secretion of inflammatory cytokines. The virulence factor detection experiments indicate that genes involved in the type IV secretion system (T4SS) and quorum sensing system (QSS) are down-regulated in 2308ΔgntR. The lower levels of survival of 2308ΔgntR under various stress conditions and the increased sensitivity of 2308ΔgntR to polymyxin B suggest that GntR is a virulence factor and that deletion of gntR reduces of B. abortus to stress conditions. Taken together, our results demonstrate that GntR is involved in the cytotoxicity, virulence and intracellular survival of B. abortus during its infection.

  2. Parallel Evolution of a Type IV Secretion System in Radiating Lineages of the Host-Restricted Bacterial Pathogen Bartonella

    Science.gov (United States)

    Engel, Philipp; Salzburger, Walter; Liesch, Marius; Chang, Chao-Chin; Maruyama, Soichi; Lanz, Christa; Calteau, Alexandra; Lajus, Aurélie; Médigue, Claudine; Schuster, Stephan C.; Dehio, Christoph

    2011-01-01

    Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered to be responsible for the genesis of a great portion of the diversity of life. Bacteria have evolved enormous biological diversity by exploiting an exceptional range of environments, yet diversification of bacteria via adaptive radiation has been documented in a few cases only and the underlying molecular mechanisms are largely unknown. Here we show a compelling example of adaptive radiation in pathogenic bacteria and reveal their genetic basis. Our evolutionary genomic analyses of the α-proteobacterial genus Bartonella uncover two parallel adaptive radiations within these host-restricted mammalian pathogens. We identify a horizontally-acquired protein secretion system, which has evolved to target specific bacterial effector proteins into host cells as the evolutionary key innovation triggering these parallel adaptive radiations. We show that the functional versatility and adaptive potential of the VirB type IV secretion system (T4SS), and thereby translocated Bartonella effector proteins (Beps), evolved in parallel in the two lineages prior to their radiations. Independent chromosomal fixation of the virB operon and consecutive rounds of lineage-specific bep gene duplications followed by their functional diversification characterize these parallel evolutionary trajectories. Whereas most Beps maintained their ancestral domain constitution, strikingly, a novel type of effector protein emerged convergently in both lineages. This resulted in similar arrays of host cell-targeted effector proteins in the two lineages of Bartonella as the basis of their independent radiation. The parallel molecular evolution of the VirB/Bep system displays a striking example of a key innovation involved in independent adaptive processes and the emergence of bacterial pathogens

  3. Parallel evolution of a type IV secretion system in radiating lineages of the host-restricted bacterial pathogen Bartonella.

    Directory of Open Access Journals (Sweden)

    Philipp Engel

    2011-02-01

    Full Text Available Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered to be responsible for the genesis of a great portion of the diversity of life. Bacteria have evolved enormous biological diversity by exploiting an exceptional range of environments, yet diversification of bacteria via adaptive radiation has been documented in a few cases only and the underlying molecular mechanisms are largely unknown. Here we show a compelling example of adaptive radiation in pathogenic bacteria and reveal their genetic basis. Our evolutionary genomic analyses of the α-proteobacterial genus Bartonella uncover two parallel adaptive radiations within these host-restricted mammalian pathogens. We identify a horizontally-acquired protein secretion system, which has evolved to target specific bacterial effector proteins into host cells as the evolutionary key innovation triggering these parallel adaptive radiations. We show that the functional versatility and adaptive potential of the VirB type IV secretion system (T4SS, and thereby translocated Bartonella effector proteins (Beps, evolved in parallel in the two lineages prior to their radiations. Independent chromosomal fixation of the virB operon and consecutive rounds of lineage-specific bep gene duplications followed by their functional diversification characterize these parallel evolutionary trajectories. Whereas most Beps maintained their ancestral domain constitution, strikingly, a novel type of effector protein emerged convergently in both lineages. This resulted in similar arrays of host cell-targeted effector proteins in the two lineages of Bartonella as the basis of their independent radiation. The parallel molecular evolution of the VirB/Bep system displays a striking example of a key innovation involved in independent adaptive processes and the emergence of bacterial

  4. Parallel evolution of a type IV secretion system in radiating lineages of the host-restricted bacterial pathogen Bartonella.

    Science.gov (United States)

    Engel, Philipp; Salzburger, Walter; Liesch, Marius; Chang, Chao-Chin; Maruyama, Soichi; Lanz, Christa; Calteau, Alexandra; Lajus, Aurélie; Médigue, Claudine; Schuster, Stephan C; Dehio, Christoph

    2011-02-10

    Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered to be responsible for the genesis of a great portion of the diversity of life. Bacteria have evolved enormous biological diversity by exploiting an exceptional range of environments, yet diversification of bacteria via adaptive radiation has been documented in a few cases only and the underlying molecular mechanisms are largely unknown. Here we show a compelling example of adaptive radiation in pathogenic bacteria and reveal their genetic basis. Our evolutionary genomic analyses of the α-proteobacterial genus Bartonella uncover two parallel adaptive radiations within these host-restricted mammalian pathogens. We identify a horizontally-acquired protein secretion system, which has evolved to target specific bacterial effector proteins into host cells as the evolutionary key innovation triggering these parallel adaptive radiations. We show that the functional versatility and adaptive potential of the VirB type IV secretion system (T4SS), and thereby translocated Bartonella effector proteins (Beps), evolved in parallel in the two lineages prior to their radiations. Independent chromosomal fixation of the virB operon and consecutive rounds of lineage-specific bep gene duplications followed by their functional diversification characterize these parallel evolutionary trajectories. Whereas most Beps maintained their ancestral domain constitution, strikingly, a novel type of effector protein emerged convergently in both lineages. This resulted in similar arrays of host cell-targeted effector proteins in the two lineages of Bartonella as the basis of their independent radiation. The parallel molecular evolution of the VirB/Bep system displays a striking example of a key innovation involved in independent adaptive processes and the emergence of bacterial pathogens

  5. Salmonella-secreted Virulence Factors

    Energy Technology Data Exchange (ETDEWEB)

    Heffron, Fred; Niemann, George; Yoon, Hyunjin; Kidwai, Afshan S.; Brown, Roslyn N.; McDermott, Jason E.; Smith, Richard D.; Adkins, Joshua N.

    2011-05-01

    In this short review we discuss secreted virulence factors of Salmonella, which directly affect Salmonella interaction with its host. Salmonella secretes protein to subvert host defenses but also, as discussed, to reduce virulence thereby permitting the bacteria to persist longer and more successfully disperse. The type III secretion system (TTSS) is the best known and well studied of the mechanisms that enable secretion from the bacterial cytoplasm to the host cell cytoplasm. Other secretion systems include outer membrane vesicles, which are present in all Gram-negative bacteria examined to date, two-partner secretion, and type VI secretion will also be addressed. Excellent reviews of Salmonella secreted effectors have focused on themes such as actin rearrangements, vesicular trafficking, ubiquitination, and the activities of the virulence factors themselves. This short review is based on S. Typhimurium infection of mice because it is a model of typhoid like disease in humans. We have organized effectors in terms of events that happen during the infection cycle and how secreted effectors may be involved.

  6. The first C4-functionalisation of condensed tannins. Phlobatannins as prototype of a new class of C-ring isomerised oligomers

    International Nuclear Information System (INIS)

    Steenkamp, J.A.

    1986-06-01

    This thesis comprises besides the characterisation of new oligomeric flavenoids from the core wood of the indigeneous Colophosphermum mopane, an investigation into the C 4 -functionalisation of flavan-3-ol analogues. The first peltogynoid biflavenoid and prototypes of a new series C-ring isomerised condensed tannins, namely the phlobatannins, were isolated. Besides 1 H- nmr-parameters for structure analysis, the natural phlobatannins were characterised and the unique ring isomerisation was investigated

  7. Vibrio parahaemolyticus type VI secretion system 1 is activated in marine conditions to target bacteria, and is differentially regulated from system 2.

    Directory of Open Access Journals (Sweden)

    Dor Salomon

    Full Text Available Vibrio parahaemolyticus is a marine bacterium that thrives in warm climates. It is a leading cause of gastroenteritis resulting from consumption of contaminated uncooked shellfish. This bacterium harbors two putative type VI secretion systems (T6SS. T6SSs are widespread protein secretion systems found in many Gram-negative bacteria, and are often tightly regulated. For many T6SSs studied to date, the conditions and cues, as well as the regulatory mechanisms that control T6SS activity are unknown. In this study, we characterized the environmental conditions and cues that activate both V. parahaemolyticus T6SSs, and identified regulatory mechanisms that control T6SS gene expression and activity. We monitored the expression and secretion of the signature T6SS secreted proteins Hcp1 and Hcp2, and found that both T6SSs are differentially regulated by quorum sensing and surface sensing. We also showed that T6SS1 and T6SS2 require different temperature and salinity conditions to be active. Interestingly, T6SS1, which is found predominantly in clinical isolates, was most active under warm marine-like conditions. Moreover, we found that T6SS1 has anti-bacterial activity under these conditions. In addition, we identified two transcription regulators in the T6SS1 gene cluster that regulate Hcp1 expression, but are not required for immunity against self-intoxication. Further examination of environmental isolates revealed a correlation between the presence of T6SS1 and virulence of V. parahaemolyticus against other bacteria, and we also showed that different V. parahaemolyticus isolates can outcompete each other. We propose that T6SS1 and T6SS2 play different roles in the V. parahaemolyticus lifestyles, and suggest a role for T6SS1 in enhancing environmental fitness of V. parahaemolyticus in marine environments when competing for a niche in the presence of other bacterial populations.

  8. Campylobacter jejuni type VI secretion system: roles in adaptation to deoxycholic acid, host cell adherence, invasion, and in vivo colonization.

    Science.gov (United States)

    Lertpiriyapong, Kvin; Gamazon, Eric R; Feng, Yan; Park, Danny S; Pang, Jassia; Botka, Georgina; Graffam, Michelle E; Ge, Zhongming; Fox, James G

    2012-01-01

    The recently identified type VI secretion system (T6SS) of proteobacteria has been shown to promote pathogenicity, competitive advantage over competing microorganisms, and adaptation to environmental perturbation. By detailed phenotypic characterization of loss-of-function mutants, in silico, in vitro and in vivo analyses, we provide evidence that the enteric pathogen, Campylobacter jejuni, possesses a functional T6SS and that the secretion system exerts pleiotropic effects on two crucial processes--survival in a bile salt, deoxycholic acid (DCA), and host cell adherence and invasion. The expression of T6SS during initial exposure to the upper range of physiological levels of DCA (0.075%-0.2%) was detrimental to C. jejuni proliferation, whereas down-regulation or inactivation of T6SS enabled C. jejuni to resist this effect. The C. jejuni multidrug efflux transporter gene, cmeA, was significantly up-regulated during the initial exposure to DCA in the wild type C. jejuni relative to the T6SS-deficient strains, suggesting that inhibition of proliferation is the consequence of T6SS-mediated DCA influx. A sequential modulation of the efflux transporter activity and the T6SS represents, in part, an adaptive mechanism for C. jejuni to overcome this inhibitory effect, thereby ensuring its survival. C. jejuni T6SS plays important roles in host cell adhesion and invasion as T6SS inactivation resulted in a reduction of adherence to and invasion of in vitro cell lines, while over-expression of a hemolysin co-regulated protein, which encodes a secreted T6SS component, greatly enhanced these processes. When inoculated into B6.129P2-IL-10(tm1Cgn) mice, the T6SS-deficient C. jejuni strains did not effectively establish persistent colonization, indicating that T6SS contributes to colonization in vivo. Taken together, our data demonstrate the importance of bacterial T6SS in host cell adhesion, invasion, colonization and, for the first time to our knowledge, adaptation to DCA

  9. Campylobacter jejuni type VI secretion system: roles in adaptation to deoxycholic acid, host cell adherence, invasion, and in vivo colonization.

    Directory of Open Access Journals (Sweden)

    Kvin Lertpiriyapong

    Full Text Available The recently identified type VI secretion system (T6SS of proteobacteria has been shown to promote pathogenicity, competitive advantage over competing microorganisms, and adaptation to environmental perturbation. By detailed phenotypic characterization of loss-of-function mutants, in silico, in vitro and in vivo analyses, we provide evidence that the enteric pathogen, Campylobacter jejuni, possesses a functional T6SS and that the secretion system exerts pleiotropic effects on two crucial processes--survival in a bile salt, deoxycholic acid (DCA, and host cell adherence and invasion. The expression of T6SS during initial exposure to the upper range of physiological levels of DCA (0.075%-0.2% was detrimental to C. jejuni proliferation, whereas down-regulation or inactivation of T6SS enabled C. jejuni to resist this effect. The C. jejuni multidrug efflux transporter gene, cmeA, was significantly up-regulated during the initial exposure to DCA in the wild type C. jejuni relative to the T6SS-deficient strains, suggesting that inhibition of proliferation is the consequence of T6SS-mediated DCA influx. A sequential modulation of the efflux transporter activity and the T6SS represents, in part, an adaptive mechanism for C. jejuni to overcome this inhibitory effect, thereby ensuring its survival. C. jejuni T6SS plays important roles in host cell adhesion and invasion as T6SS inactivation resulted in a reduction of adherence to and invasion of in vitro cell lines, while over-expression of a hemolysin co-regulated protein, which encodes a secreted T6SS component, greatly enhanced these processes. When inoculated into B6.129P2-IL-10(tm1Cgn mice, the T6SS-deficient C. jejuni strains did not effectively establish persistent colonization, indicating that T6SS contributes to colonization in vivo. Taken together, our data demonstrate the importance of bacterial T6SS in host cell adhesion, invasion, colonization and, for the first time to our knowledge

  10. CRISPR-Cas and Contact-Dependent Secretion Systems Present on Excisable Pathogenicity Islands with Conserved Recombination Modules.

    Science.gov (United States)

    Carpenter, Megan R; Kalburge, Sai S; Borowski, Joseph D; Peters, Molly C; Colwell, Rita R; Boyd, E Fidelma

    2017-05-15

    Pathogenicity islands (PAIs) are mobile integrated genetic elements that contain a diverse range of virulence factors. PAIs integrate into the host chromosome at a tRNA locus that contains their specific bacterial attachment site, attB , via integrase-mediated site-specific recombination generating attL and attR sites. We identified conserved recombination modules (integrases and att sites) previously described in choleragenic Vibrio cholerae PAIs but with novel cargo genes. Clustered regularly interspaced short palindromic repeat (CRISPR)-associated proteins (Cas proteins) and a type VI secretion system (T6SS) gene cluster were identified at the Vibrio pathogenicity island 1 (VPI-1) insertion site in 19 V. cholerae strains and contained the same recombination module. Two divergent type I-F CRISPR-Cas systems were identified, which differed in Cas protein homology and content. The CRISPR repeat sequence was identical among all V. cholerae strains, but the CRISPR spacer sequences and the number of spacers varied. In silico analysis suggests that the CRISPR-Cas systems were active against phages and plasmids. A type III secretion system (T3SS) was present in 12 V. cholerae strains on a 68-kb island inserted at the same tRNA-serine insertion site as VPI-2 and contained the same recombination module. Bioinformatics analysis showed that two divergent T3SSs exist among the strains examined. Both the CRISPR and T3SS islands excised site specifically from the bacterial chromosome as complete units, and the cognate integrases were essential for this excision. These data demonstrated that identical recombination modules that catalyze integration and excision from the chromosome can acquire diverse cargo genes, signifying a novel method of acquisition for both CRISPR-Cas systems and T3SSs. IMPORTANCE This work demonstrated the presence of CRISPR-Cas systems and T3SSs on PAIs. Our work showed that similar recombination modules can associate with different cargo genes and

  11. Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

    Science.gov (United States)

    2012-01-01

    Summary: Flagellar and translocation-associated type III secretion (T3S) systems are present in most Gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria. PMID:22688814

  12. DotU and VgrG, core components of type VI secretion systems, are essential for Francisella LVS pathogenicity.

    Directory of Open Access Journals (Sweden)

    Jeanette E Bröms

    Full Text Available The Gram-negative bacterium Francisella tularensis causes tularemia, a disease which requires bacterial escape from phagosomes of infected macrophages. Once in the cytosol, the bacterium rapidly multiplies, inhibits activation of the inflammasome and ultimately causes death of the host cell. Of importance for these processes is a 33-kb gene cluster, the Francisella pathogenicity island (FPI, which is believed to encode a type VI secretion system (T6SS. In this study, we analyzed the role of the FPI-encoded proteins VgrG and DotU, which are conserved components of type VI secretion (T6S clusters. We demonstrate that in F. tularensis LVS, VgrG was shown to form multimers, consistent with its suggested role as a trimeric membrane puncturing device in T6SSs, while the inner membrane protein DotU was shown to stabilize PdpB/IcmF, another T6SS core component. Upon infection of J774 cells, both ΔvgrG and ΔdotU mutants did not escape from phagosomes, and subsequently, did not multiply or cause cytopathogenicity. They also showed impaired activation of the inflammasome and marked attenuation in the mouse model. Moreover, all of the DotU-dependent functions investigated here required the presence of three residues that are essentially conserved among all DotU homologues. Thus, in agreement with a core function in T6S clusters, VgrG and DotU play key roles for modulation of the intracellular host response as well as for the virulence of F. tularensis.

  13. Acquired type III secretion system determines environmental fitness of epidemic Vibrio parahaemolyticus in the interaction with bacterivorous protists.

    Directory of Open Access Journals (Sweden)

    Carsten Matz

    Full Text Available Genome analyses of marine microbial communities have revealed the widespread occurrence of genomic islands (GIs, many of which encode for protein secretion machineries described in the context of bacteria-eukaryote interactions. Yet experimental support for the specific roles of such GIs in aquatic community interactions remains scarce. Here, we test for the contribution of type III secretion systems (T3SS to the environmental fitness of epidemic Vibrio parahaemolyticus. Comparisons of V. parahaemolyticus wild types and T3SS-defective mutants demonstrate that the T3SS encoded on genome island VPaI-7 (T3SS-2 promotes survival of V. parahaemolyticus in the interaction with diverse protist taxa. Enhanced persistence was found to be due to T3SS-2 mediated cytotoxicity and facultative parasitism of V. parahaemolyticus on coexisting protists. Growth in the presence of bacterivorous protists and the T3SS-2 genotype showed a strong correlation across environmental and clinical isolates of V. parahaemolyticus. Short-term microcosm experiments provide evidence that protistan hosts facilitate the invasion of T3SS-2 positive V. parahaemolyticus into a coastal plankton community, and that water temperature and productivity further promote enhanced survival of T3SS-2 positive V. parahaemolyticus. This study is the first to describe the fitness advantage of GI-encoded functions in a microbial food web, which may provide a mechanistic explanation for the global spread and the seasonal dynamics of V. parahaemolyticus pathotypes, including the pandemic serotype cluster O3:K6, in aquatic environments.

  14. The central nervous system of sea cucumbers (Echinodermata: Holothuroidea shows positive immunostaining for a chordate glial secretion

    Directory of Open Access Journals (Sweden)

    Grondona Jesus M

    2009-06-01

    Full Text Available Abstract Background Echinoderms and chordates belong to the same monophyletic taxon, the Deuterostomia. In spite of significant differences in body plan organization, the two phyla may share more common traits than was thought previously. Of particular interest are the common features in the organization of the central nervous system. The present study employs two polyclonal antisera raised against bovine Reissner's substance (RS, a secretory product produced by glial cells of the subcomissural organ, to study RS-like immunoreactivity in the central nervous system of sea cucumbers. Results In the ectoneural division of the nervous system, both antisera recognize the content of secretory vacuoles in the apical cytoplasm of the radial glia-like cells of the neuroepithelium and in the flattened glial cells of the non-neural epineural roof epithelium. The secreted immunopositive material seems to form a thin layer covering the cell apices. There is no accumulation of the immunoreactive material on the apical surface of the hyponeural neuroepithelium or the hyponeural roof epithelium. Besides labelling the supporting cells and flattened glial cells of the epineural roof epithelium, both anti-RS antisera reveal a previously unknown putative glial cell type within the neural parenchyma of the holothurian nervous system. Conclusion Our results show that: a the glial cells of the holothurian tubular nervous system produce a material similar to Reissner's substance known to be synthesized by secretory glial cells in all chordates studied so far; b the nervous system of sea cucumbers shows a previously unrealized complexity of glial organization. Our findings also provide significant clues for interpretation of the evolution of the nervous system in the Deuterostomia. It is suggested that echinoderms and chordates might have inherited the RS-producing radial glial cell type from the central nervous system of their common ancestor, i.e., the last common

  15. The global regulator Crc plays a multifaceted role in modulation of type III secretion system in Pseudomonas aeruginosa.

    Science.gov (United States)

    Dong, Yi-Hu; Zhang, Xi-Fen; Zhang, Lian-Hui

    2013-02-01

    The opportunistic pathogen Pseudomonas aeruginosa utilizes type III secretion system (T3SS) to translocate effector proteins into eukaryotic host cells that subvert normal host cell functions to the benefit of the pathogen, and results in serious infections. T3SS in P. aeruginosa is controlled by a complex system of regulatory mechanisms and signaling pathways. In this study, we described that Crc, an RNA-binding protein, exerts a positive impact on T3SS in P. aeruginosa, as evidenced by promoter activity assays of several key T3SS genes, transcriptomics, RT-PCR, and immunoblotting in crc mutant. We further demonstrated that the regulatory function of Crc on the T3SS was mediated through the T3SS master regulator ExsA and linked to the Cbr/Crc signaling system. Expression profiling of the crc mutant revealed a downregulation of flagship T3SS genes as well as 16 other genes known to regulate T3SS gene expression in P. aeruginosa. On the basis of these data, we proposed that Crc may exert multifaceted control on the T3SS through various pathways, which may serve to fine-tune this virulence mechanism in response to environmental changes and nutrient sources. © 2012 The Authors. Published by Blackwell Publishing Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  16. Influence of ESAT-6 secretion system 1 (RD1) of Mycobacterium tuberculosis on the interaction between mycobacteria and the host immune system.

    Science.gov (United States)

    Majlessi, Laleh; Brodin, Priscille; Brosch, Roland; Rojas, Marie-Jésus; Khun, Huot; Huerre, Michel; Cole, Stewart T; Leclerc, Claude

    2005-03-15

    The chromosomal locus encoding the early secreted antigenic target, 6 kDa (ESAT-6) secretion system 1 of Mycobacterium tuberculosis, also referred to as "region of difference 1 (RD1)," is absent from Mycobacterium bovis bacillus Calmette-Guerin (BCG). In this study, using low-dose aerosol infection in mice, we demonstrate that BCG complemented with RD1 (BCG::RD1) displays markedly increased virulence which albeit does not attain that of M. tuberculosis H37Rv. Nevertheless, phenotypic and functional analyses of immune cells at the site of infection show that the capacity of BCG::RD1 to initiate recruitment/activation of immune cells is comparable to that of fully virulent H37Rv. Indeed, in contrast to the parental BCG, BCG::RD1 mimics H37Rv and induces substantial influx of activated (CD44highCD45RB(-)CD62L(-)) or effector (CD45RB(-)CD27(-)) T cells and of activated CD11c(+)CD11bhigh cells to the lungs of aerosol-infected mice. For the first time, using in vivo analysis of transcriptome of inflammatory cytokines and chemokines of lung interstitial CD11c+ cells, we show that in a low-dose aerosol infection model, BCG::RD1 triggered an activation/inflammation program comparable to that induced by H37Rv while parental BCG, due to its overattenuation, did not initiate the activation program in lung interstitial CD11c+ cells. Thus, products encoded by the ESAT-6 secretion system 1 of M. tuberculosis profoundly modify the interaction between mycobacteria and the host innate and adaptive immune system. These modifications can explain the previously described improved protective capacity of BCG::RD1 vaccine candidate against M. tuberculosis challenge.

  17. Level-2 Milestone 6007: Sierra Early Delivery System Deployed to Secret Restricted Network

    Energy Technology Data Exchange (ETDEWEB)

    Bertsch, A. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-09-06

    This report documents the delivery and installation of Shark, a CORAL Sierra early delivery system deployed on the LLNL SRD network. Early ASC program users have run codes on the machine in support of application porting for the final Sierra system which will be deployed at LLNL in CY2018. In addition to the SRD resource, Shark, unclassified resources, Rzmanta and Ray, have been deployed on the LLNL Restricted Zone and Collaboration Zone networks in support of application readiness for the Sierra platform.

  18. Protein secretion and membrane insertion systems in gram-negative bacteria.

    Science.gov (United States)

    Saier, Milton H

    2006-01-01

    In contrast to other organisms, gram-negative bacteria have evolved numerous systems for protein export. Eight types are known that mediate export across or insertion into the cytoplasmic membrane, while eight specifically mediate export across or insertion into the outer membrane. Three of the former secretory pathway (SP) systems, type I SP (ISP, ABC), IIISP (Fla/Path) and IVSP (Conj/Vir), can export proteins across both membranes in a single energy-coupled step. A fourth generalized mechanism for exporting proteins across the two-membrane envelope in two distinct steps (which we here refer to as type II secretory pathways [IISP]) utilizes either the general secretory pathway (GSP or Sec) or the twin-arginine targeting translocase for translocation across the inner membrane, and either the main terminal branch or one of several protein-specific export systems for translocation across the outer membrane. We here survey the various well-characterized protein translocation systems found in living organisms and then focus on the systems present in gram-negative bacteria. Comparisons between these systems suggest specific biogenic, mechanistic and evolutionary similarities as well as major differences.

  19. A Transcriptional Regulatory Mechanism Finely Tunes the Firing of Type VI Secretion System in Response to Bacterial Enemies.

    Science.gov (United States)

    Lazzaro, Martina; Feldman, Mario F; García Véscovi, Eleonora

    2017-08-22

    The ability to detect and measure danger from an environmental signal is paramount for bacteria to respond accordingly, deploying strategies that halt or counteract potential cellular injury and maximize survival chances. Type VI secretion systems (T6SSs) are complex bacterial contractile nanomachines able to target toxic effectors into neighboring bacteria competing for the same colonization niche. Previous studies support the concept that either T6SSs are constitutively active or they fire effectors in response to various stimuli, such as high bacterial density, cell-cell contact, nutrient depletion, or components from dead sibling cells. For Serratia marcescens , it has been proposed that its T6SS is stochastically expressed, with no distinction between harmless or aggressive competitors. In contrast, we demonstrate that the Rcs regulatory system is responsible for finely tuning Serratia T6SS expression levels, behaving as a transcriptional rheostat. When confronted with harmless bacteria, basal T6SS expression levels suffice for Serratia to eliminate the competitor. A moderate T6SS upregulation is triggered when, according to the aggressor-prey ratio, an unbalanced interplay between homologous and heterologous effectors and immunity proteins takes place. Higher T6SS expression levels are achieved when Serratia is challenged by a contender like Acinetobacter , which indiscriminately fires heterologous effectors able to exert lethal cellular harm, threatening the survival of the Serratia population. We also demonstrate that Serratia 's RcsB-dependent T6SS regulatory mechanism responds not to general stress signals but to the action of specific effectors from competitors, displaying an exquisite strategy to weigh risks and keep the balance between energy expenditure and fitness costs. IMPORTANCE Serratia marcescens is among the health-threatening pathogens categorized by the WHO as research priorities to develop alternative antimicrobial strategies, and it was

  20. The influence of nutrients, biliary-pancreatic secretions, and systemic trophic hormones on intestinal adaptation in a Roux-en-Y bypass model

    DEFF Research Database (Denmark)

    Taqi, Esmaeel; Wallace, Laurie E; de Heuvel, Elaine

    2010-01-01

    The signals that govern the upregulation of nutrient absorption (adaptation) after intestinal resection are not well understood. A Gastric Roux-en-Y bypass (GRYB) model was used to isolate the relative contributions of direct mucosal stimulation by nutrients, biliary-pancreatic secretions......, and systemic enteric hormones on intestinal adaptation in short bowel syndrome....

  1. CagI is an essential component of the Helicobacter pylori Cag type IV secretion system and forms a complex with CagL.

    Directory of Open Access Journals (Sweden)

    Kieu Thuy Pham

    Full Text Available Helicobacter pylori, the causative agent of type B gastritis, peptic ulcers, gastric adenocarcinoma and MALT lymphoma, uses the Cag type IV secretion system to induce a strong proinflammatory response in the gastric mucosa and to inject its effector protein CagA into gastric cells. CagA translocation results in altered host cell gene expression profiles and cytoskeletal rearrangements, and it is considered as a major bacterial virulence trait. Recently, it has been shown that binding of the type IV secretion apparatus to integrin receptors on target cells is a crucial step in the translocation process. Several bacterial proteins, including the Cag-specific components CagL and CagI, have been involved in this interaction. Here, we have examined the localization and interactions of CagI in the bacterial cell. Since the cagI gene overlaps and is co-transcribed with the cagL gene, the role of CagI for type IV secretion system function has been difficult to assess, and conflicting results have been reported regarding its involvement in the proinflammatory response. Using a marker-free gene deletion approach and genetic complementation, we show now that CagI is an essential component of the Cag type IV secretion apparatus for both CagA translocation and interleukin-8 induction. CagI is distributed over soluble and membrane-associated pools and seems to be partly surface-exposed. Deletion of several genes encoding essential Cag components has an impact on protein levels of CagI and CagL, suggesting that both proteins require partial assembly of the secretion apparatus. Finally, we show by co-immunoprecipitation that CagI and CagL interact with each other. Taken together, our results indicate that CagI and CagL form a functional complex which is formed at a late stage of secretion apparatus assembly.

  2. Acute Hepatopancreatic Necrosis Disease-Causing Vibrio parahaemolyticus Strains Maintain an Antibacterial Type VI Secretion System with Versatile Effector Repertoires.

    Science.gov (United States)

    Li, Peng; Kinch, Lisa N; Ray, Ann; Dalia, Ankur B; Cong, Qian; Nunan, Linda M; Camilli, Andrew; Grishin, Nick V; Salomon, Dor; Orth, Kim

    2017-07-01

    Acute hepatopancreatic necrosis disease (AHPND) is a newly emerging shrimp disease that has severely damaged the global shrimp industry. AHPND is caused by toxic strains of Vibrio parahaemolyticus that have acquired a "selfish plasmid" encoding the deadly binary toxins PirA vp /PirB vp To better understand the repertoire of virulence factors in AHPND-causing V. parahaemolyticus , we conducted a comparative analysis using the genome sequences of the clinical strain RIMD2210633 and of environmental non-AHPND and toxic AHPND isolates of V. parahaemolyticus Interestingly, we found that all of the AHPND strains, but none of the non-AHPND strains, harbor the antibacterial type VI secretion system 1 (T6SS1), which we previously identified and characterized in the clinical isolate RIMD2210633. This finding suggests that the acquisition of this T6SS might confer to AHPND-causing V. parahaemolyticus a fitness advantage over competing bacteria and facilitate shrimp infection. Additionally, we found highly dynamic effector loci in the T6SS1 of AHPND-causing strains, leading to diverse effector repertoires. Our discovery provides novel insights into AHPND-causing pathogens and reveals a potential target for disease control. IMPORTANCE Acute hepatopancreatic necrosis disease (AHPND) is a serious disease that has caused severe damage and significant financial losses to the global shrimp industry. To better understand and prevent this shrimp disease, it is essential to thoroughly characterize its causative agent, Vibrio parahaemolyticus Although the plasmid-encoded binary toxins PirA vp /PirB vp have been shown to be the primary cause of AHPND, it remains unknown whether other virulent factors are commonly present in V. parahaemolyticus and might play important roles during shrimp infection. Here, we analyzed the genome sequences of clinical, non-AHPND, and AHPND strains to characterize their repertoires of key virulence determinants. Our studies reveal that an antibacterial type

  3. Uptake, translocation, and distribution of root-applied [C ring-U-14C]-ZJ0273 in plants of oilseed rape and rice

    International Nuclear Information System (INIS)

    Li Zheng; Han Ailiang; Zhang Yanfei; Li Juying; Wang Yue; Wang Haiyan; Ye Qingfu; Lu Long

    2009-01-01

    ZJ0273, propyl 4-(2-(4, 6-dimethoxypyrimidin-2-yloxy) benzylamino) benzoate, is a novel ALS-inhibited herbicide development for pre-and post-emergence weed control in field of oilseed rape. The comparative uptake, translocation and distribution of root-applied [C ring-U- 14 C] ZJ0273 in the plants of susceptible rice and tolerant oilseed rape were investigated under laboratory conditions. The results showed that the uptake of [C ring-U- 14 C]-ZJ0273 in both rice (Oryza sativa L.) and oilseed rape (Brassica napus L.) increased with time. Larger percentage of the applied ZJ0273 was uptaken by rice than oilseed rape at any sampling time. At 384 hours after treatment, the uptake of [C ring-U- 14 C]-ZJ0273 reached 24.1% of the applied amount in rice, while only 4.1% of the applied in oilseed rape. The majority of the absorbed ZJ0273 remained in the root of the tested plants, which indicated the weak mobility of ZJ0273 and/or its metabolites in both the plants of susceptible rice and tolerant oilseed rape. The radioactivity per unit of dry weight in the roots and leaves of rice was 9.470 Bq/mg and 0.910 Bq/mg, respectively, which was significantly higher than that in oilseed rape (3.870 Bq/mg and 0.390 Bq/mg). Therefore, the difference in the total uptake of ZJ0273 and the accumulation of ZJ0273 and/or its metabolites perunit of dry weight between rice and oilseed rape, which revealed in this study, might be one of the reasons for the different susceptibility of rice and oilseed rape on ZJ0273. (authors)

  4. Effects of oral stimulation with capsaicin on salivary secretion and neural activities in the autonomic system and the brain

    Directory of Open Access Journals (Sweden)

    Yoko Kono

    2018-06-01

    Conclusion: These results suggest that oral stimulation with capsaicin may be effective in improving oral conditions by increasing salivary flow and SIgA secretion, and in enhancing physical and mental conditions as indicated by sympathetic nerve and EEG changes.

  5. Oral delivery of the Sj23LHD-GST antigen by Salmonella typhimurium type III secretion system protects against Schistosoma japonicum infection in mice.

    Directory of Open Access Journals (Sweden)

    Guo Chen

    2011-09-01

    Full Text Available BACKGROUND: Schistosomiasis japonica is a zoonotic parasitic disease and oral vaccine delivery system would be benefit for prevention of this disease. Although attenuated salmonella has been used as an antigen expression vector for oral vaccine development, the membrane-bound vacuoles in which bacteria reside hinders the presentation of expressed heterologous antigens to the major histocompatibility complex (MHC molecules. The present work used an attenuated Salmonella typhimurium strain VNP20009 to secretory expression of Sj23LHDGST bivalent antigen from Schistosoma japonicum and tested the protective efficacy against S. japonicum infection in orally immunized mice. METHODOLOGY/PRINCIPAL FINDINGS: Promoters (nirB or pagC were used to express the antigen (Sj23LHDGST and the Salmonella type III or α-hemolysin secretion system was employed to secrete it. The immunoblotting analysis and fluorescent microscopy revealed that the antigen was effectively expressed and delivered to the cytosol of macrophages in vitro. Among recombinant vaccine strains, an engineered VNP20009 which expressed the antigen by nirB promoter and secreted it through type III secretion system (nirB-sopE(1-104-Sj23LHD-GST efficiently protected against S. japonicum infection in a mouse model. This strain elicited a predominantly IgG(2a antibody response and a markedly increase in the production of IL-12 and IFN-γ. The flow cytometric analysis demonstrated that this strain caused T cell activation as evidenced by significantly increased expression of CD44 and CD69. CONCLUSION/SIGNIFICANCE: Oral delivery of antigen by nirB-driven Salmonella typhimurium type III secretion system is a novel, safe, inexpensive, efficient and convenient approach for schistosome vaccine development.

  6. Structural Insights into the PorK and PorN Components of the Porphyromonas gingivalis Type IX Secretion System.

    Science.gov (United States)

    Gorasia, Dhana G; Veith, Paul D; Hanssen, Eric G; Glew, Michelle D; Sato, Keiko; Yukitake, Hideharu; Nakayama, Koji; Reynolds, Eric C

    2016-08-01

    The type IX secretion system (T9SS) has been recently discovered and is specific to Bacteroidetes species. Porphyromonas gingivalis, a keystone pathogen for periodontitis, utilizes the T9SS to transport many proteins including the gingipain virulence factors across the outer membrane and attach them to the cell surface via a sortase-like mechanism. At least 11 proteins have been identified as components of the T9SS including PorK, PorL, PorM, PorN and PorP, however the precise roles of most of these proteins have not been elucidated and the structural organization of these components is unknown. In this study, we purified PorK and PorN complexes from P. gingivalis and using electron microscopy we have shown that PorN and the PorK lipoprotein interact to form a 50 nm diameter ring-shaped structure containing approximately 32-36 subunits of each protein. The formation of these rings was dependent on both PorK and PorN, but was independent of PorL, PorM and PorP. PorL and PorM were found to form a separate stable complex. PorK and PorN were protected from proteinase K cleavage when present in undisrupted cells, but were rapidly degraded when the cells were lysed, which together with bioinformatic analyses suggests that these proteins are exposed in the periplasm and anchored to the outer membrane via the PorK lipid. Chemical cross-linking and mass spectrometry analyses confirmed the interaction between PorK and PorN and further revealed that they interact with the PG0189 outer membrane protein. Furthermore, we established that PorN was required for the stable expression of PorK, PorL and PorM. Collectively, these results suggest that the ring-shaped PorK/N complex may form part of the secretion channel of the T9SS. This is the first report showing the structural organization of any T9SS component.

  7. Structural Insights into the PorK and PorN Components of the Porphyromonas gingivalis Type IX Secretion System.

    Directory of Open Access Journals (Sweden)

    Dhana G Gorasia

    2016-08-01

    Full Text Available The type IX secretion system (T9SS has been recently discovered and is specific to Bacteroidetes species. Porphyromonas gingivalis, a keystone pathogen for periodontitis, utilizes the T9SS to transport many proteins including the gingipain virulence factors across the outer membrane and attach them to the cell surface via a sortase-like mechanism. At least 11 proteins have been identified as components of the T9SS including PorK, PorL, PorM, PorN and PorP, however the precise roles of most of these proteins have not been elucidated and the structural organization of these components is unknown. In this study, we purified PorK and PorN complexes from P. gingivalis and using electron microscopy we have shown that PorN and the PorK lipoprotein interact to form a 50 nm diameter ring-shaped structure containing approximately 32-36 subunits of each protein. The formation of these rings was dependent on both PorK and PorN, but was independent of PorL, PorM and PorP. PorL and PorM were found to form a separate stable complex. PorK and PorN were protected from proteinase K cleavage when present in undisrupted cells, but were rapidly degraded when the cells were lysed, which together with bioinformatic analyses suggests that these proteins are exposed in the periplasm and anchored to the outer membrane via the PorK lipid. Chemical cross-linking and mass spectrometry analyses confirmed the interaction between PorK and PorN and further revealed that they interact with the PG0189 outer membrane protein. Furthermore, we established that PorN was required for the stable expression of PorK, PorL and PorM. Collectively, these results suggest that the ring-shaped PorK/N complex may form part of the secretion channel of the T9SS. This is the first report showing the structural organization of any T9SS component.

  8. Type IX secretion system PorM and gliding machinery GldM form arches spanning the periplasmic space.

    Science.gov (United States)

    Leone, Philippe; Roche, Jennifer; Vincent, Maxence S; Tran, Quang Hieu; Desmyter, Aline; Cascales, Eric; Kellenberger, Christine; Cambillau, Christian; Roussel, Alain

    2018-01-30

    Type IX secretion system (T9SS), exclusively present in the Bacteroidetes phylum, has been studied mainly in Flavobacterium johnsoniae and Porphyromonas gingivalis. Among the 18 genes, essential for T9SS function, a group of four, porK-N (P. gingivalis) or gldK-N (F. johnsoniae) belongs to a co-transcribed operon that expresses the T9SS core membrane complex. The central component of this complex, PorM (or GldM), is anchored in the inner membrane by a trans-membrane helix and interacts through the outer membrane PorK-N complex. There is a complete lack of available atomic structures for any component of T9SS, including the PorKLMN complex. Here we report the crystal structure of the GldM and PorM periplasmic domains. Dimeric GldM and PorM, each contain four domains of ~180-Å length that span most of the periplasmic space. These and previously reported results allow us to propose a model of the T9SS core membrane complex as well as its functional behavior.

  9. The role of type III secretion system and lens material on adhesion of Pseudomonas aeruginosa to contact lenses.

    Science.gov (United States)

    Shen, Elizabeth P; Tsay, Ruey-Yug; Chia, Jean-San; Wu, Semon; Lee, Jing-Wen; Hu, Fung-Rong

    2012-09-21

    To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL). Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM). Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P bacteria adhering on CL surfaces. CLMK isolates were mostly of cytotoxic genotype. Different genotypes did not significantly differ in its adhesion to various CL. T3SS and other adhesins are involved in bacteria-contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.

  10. Characterization of Small Molecule Scaffolds that Bind to the Shigella Type III Secretion System Protein IpaD

    Science.gov (United States)

    Dey, Supratim; Anbanandam, Asokan; Mumford, Ben E.; De Guzman, Roberto N.

    2017-01-01

    Many pathogens such as Shigella and other bacteria assemble the type III secretion system (T3SS) nanoinjector to inject virulence proteins into their target cells to cause infectious diseases in humans. The rise of drug resistance among pathogens that rely on the T3SS for infectivity, plus the dearth of new antibiotics require alternative strategies in developing new antibiotics. The Shigella T3SS tip protein IpaD is an attractive target for developing anti-infectives because of its essential role in virulence and its exposure on the bacterial surface. Currently, the only known small molecules that bind to IpaD are bile salts sterols. Here, we identified four new small molecule scaffolds that bind to IpaD based on the methylquinoline, pyrrolidin-aniline, hydroxyindole, and morpholinoaniline scaffolds. NMR mapping revealed potential hotspots in IpaD for binding small molecules. These scaffolds can be used as building blocks in developing small molecule inhibitors of IpaD that could lead to new anti-infectives. PMID:28750143

  11. Characterization of Small-Molecule Scaffolds That Bind to the Shigella Type III Secretion System Protein IpaD.

    Science.gov (United States)

    Dey, Supratim; Anbanandam, Asokan; Mumford, Ben E; De Guzman, Roberto N

    2017-09-21

    Many pathogens such as Shigella and other bacteria assemble the type III secretion system (T3SS) nanoinjector to inject virulence proteins into their target cells to cause infectious diseases in humans. The rise of drug resistance among pathogens that rely on the T3SS for infectivity, plus the dearth of new antibiotics require alternative strategies in developing new antibiotics. The Shigella T3SS tip protein IpaD is an attractive target for developing anti-infectives because of its essential role in virulence and its exposure on the bacterial surface. Currently, the only known small molecules that bind to IpaD are bile salt sterols. In this study we identified four new small-molecule scaffolds that bind to IpaD, based on the methylquinoline, pyrrolidine-aniline, hydroxyindole, and morpholinoaniline scaffolds. NMR mapping revealed potential hotspots in IpaD for binding small molecules. These scaffolds can be used as building blocks in developing small-molecule inhibitors of IpaD that could lead to new anti-infectives. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Protein homology network families reveal step-wise diversification of Type III and Type IV secretion systems.

    Directory of Open Access Journals (Sweden)

    Duccio Medini

    2006-12-01

    Full Text Available From the analysis of 251 prokaryotic genomes stored in public databases, the 761,260 deduced proteins were used to reconstruct a complete set of bacterial proteic families. Using the new Overlap algorithm, we have partitioned the Protein Homology Network (PHN, where the proteins are the nodes and the links represent homology relationships. The algorithm identifies the densely connected regions of the PHN that define the families of homologous proteins, here called PHN-Families, recognizing the phylogenetic relationships embedded in the network. By direct comparison with a manually curated dataset, we assessed that this classification algorithm generates data of quality similar to a human expert. Then, we explored the network to identify families involved in the assembly of Type III and Type IV secretion systems (T3SS and T4SS. We noticed that, beside a core of conserved functions (eight proteins for T3SS, seven for T4SS, a variable set of accessory components is always present (one to nine for T3SS, one to five for T4SS. Each member of the core corresponds to a single PHN-Family, while accessory proteins are distributed among different pure families. The PHN-Family classification suggests that T3SS and T4SS have been assembled through a step-wise, discontinuous process, by complementing the conserved core with subgroups of nonconserved proteins. Such genetic modules, independently recruited and probably tuned on specific effectors, contribute to the functional specialization of these organelles to different microenvironments.

  13. Canada's deadly secret : Saskatchewan uranium and the global nuclear system

    Energy Technology Data Exchange (ETDEWEB)

    Harding, J.

    2007-07-01

    Although Canada has a reputation for its support of multilateralism and international peacekeeping, it has provided fuel for American and British nuclear weapons, and continues to provide uranium fuel for nuclear reactors and power plants throughout the world. This book provided a detailed outline of Canada's involvement in uranium mining in Saskatchewan, the largest uranium-producing region in the world. The ways in which Canada has been complicit in the expansion of the global nuclear system were examined. A history of the province's role in the first nuclear arms race between the Soviet Union and the United States was provided, and details of provincial public inquiries conducted to legitimize the expansion of uranium mining were revealed. Issues related to the exploitation of ancestral lands belonging to Aboriginal peoples were discussed along with the impact of uranium mining on communities in the province. It was concluded that the province is now being targeted as a storage site for nuclear waste. refs.

  14. Type III secretion system and virulence markers highlight similarities and differences between human- and plant-associated Pseudomonads related to Pseudomonas fluorescens and P-putida

    OpenAIRE

    Mazurier, Sylvie; Merieau, Annabelle; Bergeau, Dorian; Decoin, Victorien; Sperandio, Daniel; Crepin, Alexandre; Barbey, Corinne; Jeannot, Katy; Vicre-Gibouin, Maité; Plesiat, Patrick; Lemanceau, Philippe; Latour, Xavier

    2015-01-01

    Pseudomonas fluorescens is commonly considered a saprophytic rhizobacterium devoid of pathogenic potential. Nevertheless, the recurrent isolation of strains from clinical human cases could indicate the emergence of novel strains originating from the rhizosphere reservoir, which could be particularly resistant to the immune system and clinical treatment. The importance of type three secretion systems (T3SSs) in the related Pseudomonas aeruginosa nosocomial species and the occurrence of this se...

  15. First C/sub 4/-functionalisation of condensed tannins. Phlobatannins as prototype of a new class of C-ring isomerised oligomers. Die eerste C/sub 4/-funksionalisering van gekondenseerde tanniene. Flobatanniene as prototipe van 'n nuwe klas van C-ring geisomeriseerde oligomere

    Energy Technology Data Exchange (ETDEWEB)

    Steenkamp, J A

    1986-06-01

    This thesis comprises besides the characterisation of new oligomeric flavenoids from the core wood of the indigeneous Colophosphermum mopane, an investigation into the C/sub 4/-functionalisation of flavan-3-ol analogues. The first peltogynoid biflavenoid and prototypes of a new series C-ring isomerised condensed tannins, namely the phlobatannins, were isolated. Besides /sup 1/H- nmr-parameters for structure analysis, the natural phlobatannins were characterised and the unique ring isomerisation was investigated.

  16. Gene and transcript abundances of bacterial type III secretion systems from the rumen microbiome are correlated with methane yield in sheep.

    Science.gov (United States)

    Kamke, Janine; Soni, Priya; Li, Yang; Ganesh, Siva; Kelly, William J; Leahy, Sinead C; Shi, Weibing; Froula, Jeff; Rubin, Edward M; Attwood, Graeme T

    2017-08-08

    Ruminants are important contributors to global methane emissions via microbial fermentation in their reticulo-rumens. This study is part of a larger program, characterising the rumen microbiomes of sheep which vary naturally in methane yield (g CH 4 /kg DM/day) and aims to define differences in microbial communities, and in gene and transcript abundances that can explain the animal methane phenotype. Rumen microbiome metagenomic and metatranscriptomic data were analysed by Gene Set Enrichment, sparse partial least squares regression and the Wilcoxon Rank Sum test to estimate correlations between specific KEGG bacterial pathways/genes and high methane yield in sheep. KEGG genes enriched in high methane yield sheep were reassembled from raw reads and existing contigs and analysed by MEGAN to predict their phylogenetic origin. Protein coding sequences from Succinivibrio dextrinosolvens strains were analysed using Effective DB to predict bacterial type III secreted proteins. The effect of S. dextrinosolvens strain H5 growth on methane formation by rumen methanogens was explored using co-cultures. Detailed analysis of the rumen microbiomes of high methane yield sheep shows that gene and transcript abundances of bacterial type III secretion system genes are positively correlated with methane yield in sheep. Most of the bacterial type III secretion system genes could not be assigned to a particular bacterial group, but several genes were affiliated with the genus Succinivibrio, and searches of bacterial genome sequences found that strains of S. dextrinosolvens were part of a small group of rumen bacteria that encode this type of secretion system. In co-culture experiments, S. dextrinosolvens strain H5 showed a growth-enhancing effect on a methanogen belonging to the order Methanomassiliicoccales, and inhibition of a representative of the Methanobrevibacter gottschalkii clade. This is the first report of bacterial type III secretion system genes being associated with high

  17. Identification of VceA and VceC, two members of the VjbR regulon that are translocated into macrophages by the Brucella type IV secretion system

    NARCIS (Netherlands)

    de Jong, Maarten F.; Sun, Yao-Hui; den Hartigh, Andreas B.; van Dijl, Jan Maarten; Tsolis, Renee M.

    2008-01-01

    Survival and replication inside host cells by Brucella spp. requires a type IV secretion system (T4SS), encoded by the virB locus. However, the identity of the molecules secreted by the T4SS has remained elusive. We hypothesized that proteins translocated by the T4SS would be co-regulated with the

  18. Peptide Nucleic Acid Knockdown and Intra-host Cell Complementation of Ehrlichia Type IV Secretion System Effector

    Directory of Open Access Journals (Sweden)

    Pratibha Sharma

    2017-06-01

    Full Text Available Survival of Ehrlichia chaffeensis depends on obligatory intracellular infection. One of the barriers to E. chaffeensis research progress has been the inability, using conventional techniques, to generate knock-out mutants for genes essential for intracellular infection. This study examined the use of Peptide Nucleic Acids (PNAs technology to interrupt type IV secretion system (T4SS effector protein expression in E. chaffeensis followed by intracellular complementation of the effector to determine its requirement for infection. Successful E. chaffeensis infection depends on the E. chaffeensis-specific T4SS protein effector, ehrlichial translocated factor-1 (Etf-1, which induces Rab5-regulated autophagy to provide host cytosolic nutrients required for E. chaffeensis proliferation. Etf-1 is also imported by host cell mitochondria where it inhibits host cell apoptosis to prolong its infection. We designed a PNA specific to Etf-1 and showed that the PNA bound to the target region of single-stranded Etf-1 RNA using a competitive binding assay. Electroporation of E. chaffeensis with this PNA significantly reduced Etf-1 mRNA and protein, and the bacteria's ability to induce host cell autophagy and infect host cells. Etf-1 PNA-mediated inhibition of ehrlichial Etf-1 expression and E. chaffeensis infection could be intracellularly trans-complemented by ectopic expression of Etf-1-GFP in host cells. These data affirmed the critical role of bacterial T4SS effector in host cell autophagy and E. chaffeensis infection, and demonstrated the use of PNA to analyze the gene functions of obligate intracellular bacteria.

  19. Correction: The role of coupled positive feedback in the expression of the SPI1 type three secretion system in Salmonella.

    Directory of Open Access Journals (Sweden)

    Supreet Saini

    2010-08-01

    Full Text Available Salmonella enterica serovar Typhimurium is a common food-borne pathogen that induces inflammatory diarrhea and invades intestinal epithelial cells using a type three secretion system (T3SS encoded within Salmonella pathogenicity island 1 (SPI1. The genes encoding the SPI1 T3SS are tightly regulated by a network of interacting transcriptional regulators involving three coupled positive feedback loops. While the core architecture of the SPI1 gene circuit has been determined, the relative roles of these interacting regulators and associated feedback loops are still unknown. To determine the function of this circuit, we measured gene expression dynamics at both population and single-cell resolution in a number of SPI1 regulatory mutants. Using these data, we constructed a mathematical model of the SPI1 gene circuit. Analysis of the model predicted that the circuit serves two functions. The first is to place a threshold on SPI1 activation, ensuring that the genes encoding the T3SS are expressed only in response to the appropriate combination of environmental and cellular cues. The second is to amplify SPI1 gene expression. To experimentally test these predictions, we rewired the SPI1 genetic circuit by changing its regulatory architecture. This enabled us to directly test our predictions regarding the function of the circuit by varying the strength and dynamics of the activating signal. Collectively, our experimental and computational results enable us to deconstruct this complex circuit and determine the role of its individual components in regulating SPI1 gene expression dynamics.

  20. Key steps in type III secretion system (T3SS) towards translocon assembly with potential sensor at plant plasma membrane.

    Science.gov (United States)

    Ji, Hongtao; Dong, Hansong

    2015-09-01

    Many plant- and animal-pathogenic Gram-negative bacteria employ the type III secretion system (T3SS) to translocate effector proteins from bacterial cells into the cytosol of eukaryotic host cells. The effector translocation occurs through an integral component of T3SS, the channel-like translocon, assembled by hydrophilic and hydrophobic proteinaceous translocators in a two-step process. In the first, hydrophilic translocators localize to the tip of a proteinaceous needle in animal pathogens, or a proteinaceous pilus in plant pathogens, and associate with hydrophobic translocators, which insert into host plasma membranes in the second step. However, the pilus needs to penetrate plant cell walls in advance. All hydrophilic translocators so far identified in plant pathogens are characteristic of harpins: T3SS accessory proteins containing a unitary hydrophilic domain or an additional enzymatic domain. Two-domain harpins carrying a pectate lyase domain potentially target plant cell walls and facilitate the penetration of the pectin-rich middle lamella by the bacterial pilus. One-domain harpins target plant plasma membranes and may play a crucial role in translocon assembly, which may also involve contrapuntal associations of hydrophobic translocators. In all cases, sensory components in the target plasma membrane are indispensable for the membrane recognition of translocators and the functionality of the translocon. The conjectural sensors point to membrane lipids and proteins, and a phosphatidic acid and an aquaporin are able to interact with selected harpin-type translocators. Interactions between translocators and their sensors at the target plasma membrane are assumed to be critical for translocon assembly. © 2014 BSPP AND JOHN WILEY & SONS LTD.

  1. Catechin secretion and phytotoxicity

    Science.gov (United States)

    Kaushik, Shail

    2010-01-01

    Research indicates that the invasiveness of Centaurea stoebe is attributed to the stronger allelopathic effects on the native North American species than on the related European species, which is one of the unquestionable aspects of the “novel weapons hypothesis (NWH).” Studies originating from controlled to field conditions have shown that C. stoebe utilizes its biochemical potential to exert its invasiveness. The roots of C. stoebe secrete a potent phytotoxin, catechin, which has a detrimental effect on the surrounding plant species. Although, studies on catechin secretion and phytotoxicity represent one of the most well studied systems describing negative plant-plant interactions, it has also sparked controversies lately due to its phytotoxicity dosages and secretion effluxes. Previous reports negate the phytotoxic and pro-oxidant nature of catechin.1–3 In our recent study we have shown that catechin is highly phytotoxic against Arabidopsis thaliana and Festuca idahoensis. We also show that (±) catechin applied to roots of A. thaliana induces reactive oxygen species (ROS) confirming the pro-oxidant nature of catechin. In addition, activation of signature cell death genes such as acd2 and cad1 post catechin treatment in A. thaliana ascertains the phytotoxic nature of catechin. PMID:21057643

  2. Bile Formation and Secretion

    Science.gov (United States)

    Boyer, James L.

    2014-01-01

    Bile is a unique and vital aqueous secretion of the liver that is formed by the hepatocyte and modified down stream by absorptive and secretory properties of the bile duct epithelium. Approximately 5% of bile consists of organic and inorganic solutes of considerable complexity. The bile-secretory unit consists of a canalicular network which is formed by the apical membrane of adjacent hepatocytes and sealed by tight junctions. The bile canaliculi (~1 μm in diameter) conduct the flow of bile countercurrent to the direction of portal blood flow and connect with the canal of Hering and bile ducts which progressively increase in diameter and complexity prior to the entry of bile into the gallbladder, common bile duct, and intestine. Canalicular bile secretion is determined by both bile salt-dependent and independent transport systems which are localized at the apical membrane of the hepatocyte and largely consist of a series of adenosine triphosphate-binding cassette transport proteins that function as export pumps for bile salts and other organic solutes. These transporters create osmotic gradients within the bile canalicular lumen that provide the driving force for movement of fluid into the lumen via aquaporins. Species vary with respect to the relative amounts of bile salt-dependent and independent canalicular flow and cholangiocyte secretion which is highly regulated by hormones, second messengers, and signal transduction pathways. Most determinants of bile secretion are now characterized at the molecular level in animal models and in man. Genetic mutations serve to illuminate many of their functions. PMID:23897680

  3. The type VI secretion system encoded in SPI-6 plays a role in gastrointestinal colonization and systemic spread of Salmonella enterica serovar Typhimurium in the chicken.

    Directory of Open Access Journals (Sweden)

    David Pezoa

    Full Text Available The role of the Salmonella Pathogenicity Islands (SPIs in pathogenesis of Salmonella enterica Typhimurium infection in the chicken is poorly studied, while many studies have been completed in murine models. The Type VI Secretion System (T6SS is a recently described protein secretion system in Gram-negative bacteria. The genus Salmonella contains five phylogenetically distinct T6SS encoded in differentially distributed genomic islands. S. Typhimurium harbors a T6SS encoded in SPI-6 (T6SSSPI-6, which contributes to the ability of Salmonella to colonize mice. On the other hand, serotype Gallinarum harbors a T6SS encoded in SPI-19 (T6SSSPI-19 that is required for colonization of chicks. In this work, we investigated the role of T6SSSPI-6 in infection of chicks by S. Typhimurium. Oral infection of White Leghorn chicks showed that a ΔT6SSSPI-6 mutant had reduced colonization of the gut and internal organs, compared with the wild-type strain. Transfer of the intact T6SSSPI-6 gene cluster into the T6SS mutant restored bacterial colonization. In addition, our results showed that transfer of T6SSSPI-19 from S. Gallinarum to the ΔT6SSSPI-6 mutant of S. Typhimurium not only complemented the colonization defect but also resulted in a transient increase in the colonization of the cecum and ileum of chicks at days 1 and 3 post-infection. Our data indicates that T6SSSPI-6 contributes to chicken colonization and suggests that both T6SSSPI-6 and T6SSSPI-19 perform similar functions in vivo despite belonging to different phylogenetic families.

  4. Comparative genomic analysis uncovers 3 novel loci encoding type six secretion systems differentially distributed in Salmonella serotypes

    Directory of Open Access Journals (Sweden)

    Santiviago Carlos A

    2009-08-01

    Full Text Available Abstract Background The recently described Type VI Secretion System (T6SS represents a new paradigm of protein secretion in bacteria. A number of bioinformatic studies have been conducted to identify T6SS gene clusters in the available bacterial genome sequences. According to these studies, Salmonella harbors a unique T6SS encoded in the Salmonella Pathogenicity Island 6 (SPI-6. Since these studies only considered few Salmonella genomes, the present work aimed to identify novel T6SS loci by in silico analysis of every genome sequence of Salmonella available. Results The analysis of sequencing data from 44 completed or in progress Salmonella genome projects allowed the identification of 3 novel T6SS loci. These clusters are located in differentially-distributed genomic islands we designated SPI-19, SPI-20 and SPI-21, respectively. SPI-19 was identified in a subset of S. enterica serotypes including Dublin, Weltevreden, Agona, Gallinarum and Enteritidis. In the later, an internal deletion eliminated most of the island. On the other hand, SPI-20 and SPI-21 were restricted to S. enterica subspecies arizonae (IIIa serotype 62:z4,z23:-. Remarkably, SPI-21 encodes a VgrG protein containing a C-terminal extension similar to S-type pyocins of Pseudomonas aeruginosa. This is not only the first evolved VgrG described in Salmonella, but also the first evolved VgrG including a pyocin domain described so far in the literature. In addition, the data indicate that SPI-6 T6SS is widely distributed in S. enterica and absent in serotypes Enteritidis, Gallinarum, Agona, Javiana, Paratyphi B, Virchow, IIIa 62:z4,z23:- and IIIb 61:1,v:1,5,(7. Interestingly, while some serotypes harbor multiple T6SS (Dublin, Weltvreden and IIIa 62:z4,z23:- others do not encode for any (Enteritidis, Paratyphi B, Javiana, Virchow and IIIb 61:1,v:1,5,(7. Comparative and phylogenetic analyses indicate that the 4 T6SS loci in Salmonella have a distinct evolutionary history. Finally, we

  5. Mass spectrometry-based proteomic exploration of the human immune system: focus on the inflammasome, global protein secretion, and T cells.

    Science.gov (United States)

    Nyman, Tuula A; Lorey, Martina B; Cypryk, Wojciech; Matikainen, Sampsa

    2017-05-01

    The immune system is our defense system against microbial infections and tissue injury, and understanding how it works in detail is essential for developing drugs for different diseases. Mass spectrometry-based proteomics can provide in-depth information on the molecular mechanisms involved in immune responses. Areas covered: Summarized are the key immunology findings obtained with MS-based proteomics in the past five years, with a focus on inflammasome activation, global protein secretion, mucosal immunology, immunopeptidome and T cells. Special focus is on extracellular vesicle-mediated protein secretion and its role in immune responses. Expert commentary: Proteomics is an essential part of modern omics-scale immunology research. To date, MS-based proteomics has been used in immunology to study protein expression levels, their subcellular localization, secretion, post-translational modifications, and interactions in immune cells upon activation by different stimuli. These studies have made major contributions to understanding the molecular mechanisms involved in innate and adaptive immune responses. New developments in proteomics offer constantly novel possibilities for exploring the immune system. Examples of these techniques include mass cytometry and different MS-based imaging approaches which can be widely used in immunology.

  6. A gene transfer agent and a dynamic repertoire of secretion systems hold the keys to the explosive radiation of the emerging pathogen Bartonella.

    Directory of Open Access Journals (Sweden)

    Lionel Guy

    2013-03-01

    Full Text Available Gene transfer agents (GTAs randomly transfer short fragments of a bacterial genome. A novel putative GTA was recently discovered in the mouse-infecting bacterium Bartonella grahamii. Although GTAs are widespread in phylogenetically diverse bacteria, their role in evolution is largely unknown. Here, we present a comparative analysis of 16 Bartonella genomes ranging from 1.4 to 2.6 Mb in size, including six novel genomes from Bartonella isolated from a cow, two moose, two dogs, and a kangaroo. A phylogenetic tree inferred from 428 orthologous core genes indicates that the deadly human pathogen B. bacilliformis is related to the ruminant-adapted clade, rather than being the earliest diverging species in the genus as previously thought. A gene flux analysis identified 12 genes for a GTA and a phage-derived origin of replication as the most conserved innovations. These are located in a region of a few hundred kb that also contains 8 insertions of gene clusters for type III, IV, and V secretion systems, and genes for putatively secreted molecules such as cholera-like toxins. The phylogenies indicate a recent transfer of seven genes in the virB gene cluster for a type IV secretion system from a cat-adapted B. henselae to a dog-adapted B. vinsonii strain. We show that the B. henselae GTA is functional and can transfer genes in vitro. We suggest that the maintenance of the GTA is driven by selection to increase the likelihood of horizontal gene transfer and argue that this process is beneficial at the population level, by facilitating adaptive evolution of the host-adaptation systems and thereby expansion of the host range size. The process counters gene loss and forces all cells to contribute to the production of the GTA and the secreted molecules. The results advance our understanding of the role that GTAs play for the evolution of bacterial genomes.

  7. Histaminergic regulation of prolactin secretion

    DEFF Research Database (Denmark)

    Knigge, U P

    1990-01-01

    Histamine (HA), which acts as a neurotransmitter in the central nervous system, participates in the neuroendocrine regulation of prolactin (PRL) secretion. HA has a predominant stimulatory effect which is mediated via H2-receptors following central administration and via H1-receptors following...... systemic infusion of the amine. In addition, HA seems to exert a minor inhibitory effect on PRL secretion, an effect unmasked only during blockade of the receptor mediating the stimulatory effect. Following central administration the inhibitory effect is mediated via H1-receptors, while following systemic...... administration this effect is mediated via H2-receptors. In accordance with these findings, the H2-receptor antagonist cimetidine (CIM) has an inhibitory (following central administration) or stimulatory (following systemic administration) effect on PRL secretion. However, high doses of CIM possess an additional...

  8. N-acetylcolchinol O-methyl ether and thiocolchicine, potent analogs of colchicine modified in the C ring. Evaluation of the mechanistic basis for their enhanced biological properties

    International Nuclear Information System (INIS)

    Kang, G.J.; Getahun, Z.; Muzaffar, A.; Brossi, A.; Hamel, E.

    1990-01-01

    Two colchicine analogs with modifications only in the C ring are better inhibitors than colchicine of cell growth and tubulin polymerization. Radiolabeled thiocolchicine (with a thiomethyl instead of a methoxy group at position C-10) and N-acetylcolchinol O-methyl ether (NCME) (with a methoxy-substituted benzenoid instead of the methoxy-substituted tropone C ring) were prepared for comparison with colchicine. Scatchard analysis indicated a single binding site with KD values of 1.0-2.3 microM. Thiocolchicine was bound 2-4 times as rapidly as colchicine, but the activation energies of the reactions were nearly identical (18 kcal/mol for colchicine, 20 kcal/mol for thiocolchicine). NCME bound to tubulin in a biphasic reaction. The faster phase was 60 times as fast as colchicine binding at 37 degrees C, and a substantial reaction occurred at 0 degrees C. The rate of the faster phase of NCME binding changed relatively little as a function of temperature, so the activation energy was only 7.0 kcal/mol. Dissociation reactions were also evaluated, and at 37 degrees C the half-lives of the tubulin-drug complexes were 11 min for NCME, 24 h for thiocolchicine, and 27 h for colchicine. Relative dissociation rates as a function of temperature varied little among the drug complexes. Activation energies for the dissociation reactions were 30 kcal/mol for thiocolchicine, 27 kcal/mol for NCME, and 24 kcal/mol for colchicine. Comparison of the activation energies of association and dissociation yielded free energies for the binding reactions of -20 kcal/mol for NCME, -10 kcal/mol for thiocolchicine, and -6 kcal/mol for colchicine. The greater effectiveness of NCME and thiocolchicine as compared with colchicine in biological assays probably derives from their more rapid binding to tubulin and the lower free energies of their binding reactions

  9. Membrane fusion proteins of type I secretion system and tripartite efflux pumps share a binding motif for TolC in gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Minho Lee

    Full Text Available The Hly translocator complex of Escherichia coli catalyzes type I secretion of the toxin hemolysin A (HlyA. In this complex, HlyB is an inner membrane ABC (ATP Binding Cassette-type transporter, TolC is an outer membrane channel protein, and HlyD is a periplasmic adaptor anchored in the inner membrane that bridges HlyB to TolC. This tripartite organization is reminiscent of that of drug efflux systems such as AcrA-AcrB-TolC and MacA-MacB-TolC of E. coli. We have previously shown the crucial role of conserved residues located at the hairpin tip region of AcrA and MacA adaptors during assembly of their cognate systems. In this study, we investigated the role of the putative tip region of HlyD using HlyD mutants with single amino acid substitutions at the conserved positions. In vivo and in vitro data show that all mutations abolished HlyD binding to TolC and resulted in the absence of HlyA secretion. Together, our results suggest that, similarly to AcrA and MacA, HlyD interacts with TolC in a tip-to-tip manner. A general model in which these conserved interactions induce opening of TolC during drug efflux and type I secretion is discussed.

  10. Escherichia coli type III secretion system 2 (ETT2) is widely distributed in avian pathogenic Escherichia coli isolates from Eastern China.

    Science.gov (United States)

    Wang, S; Liu, X; Xu, X; Zhao, Y; Yang, D; Han, X; Tian, M; Ding, C; Peng, D; Yu, S

    2016-10-01

    Pathogens utilize type III secretion systems to deliver effector proteins, which facilitate bacterial infections. The Escherichia coli type III secretion system 2 (ETT2) which plays a crucial role in bacterial virulence, is present in the majority of E. coli strains, although ETT2 has undergone widespread mutational attrition. We investigated the distribution and characteristics of ETT2 in avian pathogenic E. coli (APEC) isolates and identified five different ETT2 isoforms, including intact ETT2, in 57·6% (141/245) of the isolates. The ETT2 locus was present in the predominant APEC serotypes O78, O2 and O1. All of the ETT2 loci in the serotype O78 isolates were degenerate, whereas an intact ETT2 locus was mostly present in O1 and O2 serotype strains, which belong to phylogenetic groups B2 and D, respectively. Interestingly, a putative second type III secretion-associated locus (eip locus) was present only in the isolates with an intact ETT2. Moreover, ETT2 was more widely distributed in APEC isolates and exhibited more isoforms compared to ETT2 in human extraintestinal pathogenic E. coli, suggesting that APEC might be a potential risk to human health. However, there was no distinct correlation between ETT2 and other virulence factors in APEC.

  11. Windows 8 secrets

    CERN Document Server

    Thurrott, Paul

    2012-01-01

    Tips, tricks, treats, and secrets revealed on Windows 8 Microsoft is introducing a major new release of its Windows operating system, Windows 8, and what better way to learn all its ins and outs than from two internationally recognized Windows experts and Microsoft insiders, authors Paul Thurrott and Rafael Rivera? They cut through the hype to get at useful information you'll not find anywhere else, including what role this new OS plays in a mobile and tablet world. Regardless of your level of knowledge, you'll discover little-known facts about how things work, what's new and different, and h

  12. Comparative Genomics Identifies a Novel Conserved Protein, HpaT, in Proteobacterial Type III Secretion Systems that Do Not Possess the Putative Translocon Protein HrpF

    Directory of Open Access Journals (Sweden)

    Céline Pesce

    2017-06-01

    Full Text Available Xanthomonas translucens is the causal agent of bacterial leaf streak, the most common bacterial disease of wheat and barley. To cause disease, most xanthomonads depend on a highly conserved type III secretion system, which translocates type III effectors into host plant cells. Mutagenesis of the conserved type III secretion gene hrcT confirmed that the X. translucens type III secretion system is required to cause disease on the host plant barley and to trigger a non-host hypersensitive response (HR in pepper leaves. Type III effectors are delivered to the host cell by a surface appendage, the Hrp pilus, and a translocon protein complex that inserts into the plant cell plasma membrane. Homologs of the Xanthomonas HrpF protein, including PopF from Ralstonia solanacearum and NolX from rhizobia, are thought to act as a translocon protein. Comparative genomics revealed that X. translucens strains harbor a noncanonical hrp gene cluster, which rather shares features with type III secretion systems from Ralstonia solanacearum, Paraburkholderia andropogonis, Collimonas fungivorans, and Uliginosibacterium gangwonense than other Xanthomonas spp. Surprisingly, none of these bacteria, except R. solanacearum, encode a homolog of the HrpF translocon. Here, we aimed at identifying a candidate translocon from X. translucens. Notably, genomes from strains that lacked hrpF/popF/nolX instead encode another gene, called hpaT, adjacent to and co-regulated with the type III secretion system gene cluster. An insertional mutant in the X. translucens hpaT gene, which is the first gene of a two-gene operon, hpaT-hpaH, was non-pathogenic on barley and did not cause the HR or programmed cell death in non-host pepper similar to the hrcT mutant. The hpaT mutant phenotypes were partially complemented by either hpaT or the downstream gene, hpaH, which has been described as a facilitator of translocation in Xanthomonas oryzae. Interestingly, the hpaT mutant was also complemented

  13. Facilitated saliva secretion and reduced oral inflammation by a novel artificial saliva system in the treatment of salivary hypofunction

    Directory of Open Access Journals (Sweden)

    Kang M

    2017-01-01

    Full Text Available Minkyung Kang,1 Hyounggeun Park,1 Joon-Ho Jun,1 Miwon Son,1 Myung Joo Kang2 1Pharmaceutical Product Research Laboratories, Dong-A ST Research Institute, Gyeonggi, 2Division of Pharmaceutical Sciences, College of Pharmacy, Dankook University, Cheonan, Chungnam, Korea Abstract: Saliva substitutes and/or lubricants are commonly employed to lessen dry mouth symptoms by stimulating and/or substituting for the secretion of saliva. In this study, a novel artificial saliva containing inorganic salts, including sodium chloride and potassium chloride, and bactericidal agents, including potassium thiocyanate and lactoperoxidase, was formulated in the form of a solution (DM-sol or gel (DM-gel. Those in vivo therapeutic efficacies were assessed in terms of saliva secretion and anti-inflammatory activity in rats and mice, respectively. Salivary secretion was promoted by mucosal application of DM-formulations in normal rats. In particular, DM-gel resulted in 2.5- and 1.9-fold greater salivary flow rates compared to normal saline and DM-sol, respectively. In an in vivo efficacy evaluation in diabetic mice with salivary hypofunction, repeated application of DM-formulations alleviated histopathological changes in the buccal mucosa in terms of atrophy and thinning of the epithelium, compared to vehicle, after 4 weeks. Moreover, the DM-sol and DM-gel were comparably effective for relieving periodontal gingivitis, reducing infiltration of inflammatory cells, and normalizing the neutrophil level in the gingival gingiva, after 4 weeks. Therefore, the novel artificial saliva is expected to facilitate salivary secretion and restore physiological conditions in the mouth of patients with salivary hypofunction. Keywords: saliva substitute, carbopol gel, hypothiocyanite–hydrogen peroxide mixture, antimicrobial activity, diabetic rats

  14. Assembly of the Type II Secretion System such as Found in Vibrio cholerae Depends on the Novel Pilotin AspS

    Science.gov (United States)

    Dunstan, Rhys A.; Heinz, Eva; Wijeyewickrema, Lakshmi C.; Pike, Robert N.; Purcell, Anthony W.; Evans, Timothy J.; Praszkier, Judyta; Robins-Browne, Roy M.; Strugnell, Richard A.; Korotkov, Konstantin V.; Lithgow, Trevor

    2013-01-01

    The Type II Secretion System (T2SS) is a molecular machine that drives the secretion of fully-folded protein substrates across the bacterial outer membrane. A key element in the machinery is the secretin: an integral, multimeric outer membrane protein that forms the secretion pore. We show that three distinct forms of T2SSs can be distinguished based on the sequence characteristics of their secretin pores. Detailed comparative analysis of two of these, the Klebsiella-type and Vibrio-type, showed them to be further distinguished by the pilotin that mediates their transport and assembly into the outer membrane. We have determined the crystal structure of the novel pilotin AspS from Vibrio cholerae, demonstrating convergent evolution wherein AspS is functionally equivalent and yet structurally unrelated to the pilotins found in Klebsiella and other bacteria. AspS binds to a specific targeting sequence in the Vibrio-type secretins, enhances the kinetics of secretin assembly, and homologs of AspS are found in all species of Vibrio as well those few strains of Escherichia and Shigella that have acquired a Vibrio-type T2SS. PMID:23326233

  15. Orientia tsutsugamushi ankyrin repeat-containing protein family members are Type 1 secretion system substrates that traffic to the host cell endoplasmic reticulum.

    Science.gov (United States)

    VieBrock, Lauren; Evans, Sean M; Beyer, Andrea R; Larson, Charles L; Beare, Paul A; Ge, Hong; Singh, Smita; Rodino, Kyle G; Heinzen, Robert A; Richards, Allen L; Carlyon, Jason A

    2014-01-01

    Scrub typhus is an understudied, potentially fatal infection that threatens one billion persons in the Asia-Pacific region. How the causative obligate intracellular bacterium, Orientia tsutsugamushi, facilitates its intracellular survival and pathogenesis is poorly understood. Many intracellular bacterial pathogens utilize the Type 1 (T1SS) or Type 4 secretion system (T4SS) to translocate ankyrin repeat-containing proteins (Anks) that traffic to distinct subcellular locations and modulate host cell processes. The O. tsutsugamushi genome encodes one of the largest known bacterial Ank repertoires plus T1SS and T4SS components. Whether these potential virulence factors are expressed during infection, how the Anks are potentially secreted, and to where they localize in the host cell are not known. We determined that O. tsutsugamushi transcriptionally expresses 20 unique ank genes as well as genes for both T1SS and T4SS during infection of mammalian host cells. Examination of the Anks' C-termini revealed that the majority of them resemble T1SS substrates. Escherichia coli expressing a functional T1SS was able to secrete chimeric hemolysin proteins bearing the C-termini of 19 of 20 O. tsutsugamushi Anks in an HlyBD-dependent manner. Thus, O. tsutsugamushi Anks C-termini are T1SS-compatible. Conversely, Coxiella burnetii could not secrete heterologously expressed Anks in a T4SS-dependent manner. Analysis of the subcellular distribution patterns of 20 ectopically expressed Anks revealed that, while 6 remained cytosolic or trafficked to the nucleus, 14 localized to, and in some cases, altered the morphology of the endoplasmic reticulum. This study identifies O. tsutsugamushi Anks as T1SS substrates and indicates that many display a tropism for the host cell secretory pathway.

  16. Immunoglobins in mammary secretions

    DEFF Research Database (Denmark)

    Hurley, W L; Theil, Peter Kappel

    2013-01-01

    Immunoglobulins secreted in colostrum and milk by the lactating mammal are major factors providing immune protection to the newborn. Immunoglobulins in mammary secretions represent the cumulative immune response of the lactating animal to exposure to antigenic stimulation that occurs through...... the immunoglobulins found in mammary secretions in the context of their diversity of structure, origin, mechanisms of transfer, and function....

  17. The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems.

    Directory of Open Access Journals (Sweden)

    Sophie S Abby

    2012-09-01

    Full Text Available Type 3 secretion systems (T3SSs are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS, which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems.

  18. Structural Characterization and Oligomerization of the TssL Protein, a Component Shared by Bacterial Type VI and Type IVb Secretion Systems*

    Science.gov (United States)

    Durand, Eric; Zoued, Abdelrahim; Spinelli, Silvia; Watson, Paul J. H.; Aschtgen, Marie-Stéphanie; Journet, Laure; Cambillau, Christian; Cascales, Eric

    2012-01-01

    The Type VI secretion system (T6SS) is a macromolecular system distributed in Gram-negative bacteria, responsible for the secretion of effector proteins into target cells. The T6SS has a broad versatility as it can target both eukaryotic and prokaryotic cells. It is therefore involved in host pathogenesis or killing neighboring bacterial cells to colonize a new niche. At the architecture level, the T6SS core apparatus is composed of 13 proteins, which assemble in two subcomplexes. One of these subcomplexes, composed of subunits that share structural similarities with bacteriophage tail and baseplate components, is anchored to the cell envelope by the membrane subcomplex. This latter is constituted of at least three proteins, TssL, TssM, and TssJ. The crystal structure of the TssJ outer membrane lipoprotein and its interaction with the inner membrane TssM protein have been recently reported. TssL and TssM share sequence homology and characteristics with two components of the Type IVb secretion system (T4bSS), IcmH/DotU and IcmF, respectively. In this study, we report the crystal structure of the cytoplasmic domain of the TssL inner membrane protein from the enteroaggregative Escherichia coli Sci-1 T6SS. It folds as a hook-like structure composed of two three-helix bundles. Two TssL molecules associate to form a functional complex. Although the TssL trans-membrane segment is the main determinant of self-interaction, contacts between the cytoplasmic domains are required for TssL function. Based on sequence homology and secondary structure prediction, we propose that the TssL structure is the prototype for the members of the TssL and IcmH/DotU families. PMID:22371492

  19. Central nervous system neuropeptide Y regulates mediators of hepatic phospholipid remodeling and very low-density lipoprotein triglyceride secretion via sympathetic innervation

    Science.gov (United States)

    Rojas, Jennifer M.; Bruinstroop, Eveline; Printz, Richard L.; Alijagic-Boers, Aldijana; Foppen, Ewout; Turney, Maxine K.; George, Leena; Beck-Sickinger, Annette G.; Kalsbeek, Andries; Niswender, Kevin D.

    2015-01-01

    Objective Elevated very low-density lipoprotein (VLDL)-triglyceride (TG) secretion from the liver contributes to an atherogenic dyslipidemia that is associated with obesity, diabetes and the metabolic syndrome. Numerous models of obesity and diabetes are characterized by increased central nervous system (CNS) neuropeptide Y (NPY); in fact, a single intracerebroventricular (icv) administration of NPY in lean fasted rats elevates hepatic VLDL-TG secretion and does so, in large part, via signaling through the CNS NPY Y1 receptor. Thus, our overarching hypothesis is that elevated CNS NPY action contributes to dyslipidemia by activating central circuits that modulate liver lipid metabolism. Methods Chow-fed Zucker fatty (ZF) rats were pair-fed by matching their caloric intake to that of lean controls and effects on body weight, plasma TG, and liver content of TG and phospholipid (PL) were compared to ad-libitum (ad-lib) fed ZF rats. Additionally, lean 4-h fasted rats with intact or disrupted hepatic sympathetic innervation were treated with icv NPY or NPY Y1 receptor agonist to identify novel hepatic mechanisms by which NPY promotes VLDL particle maturation and secretion. Results Manipulation of plasma TG levels in obese ZF rats, through pair-feeding had no effect on liver TG content; however, hepatic PL content was substantially reduced and was tightly correlated with plasma TG levels. Treatment with icv NPY or a selective NPY Y1 receptor agonist in lean fasted rats robustly activated key hepatic regulatory proteins, stearoyl-CoA desaturase-1 (SCD-1), ADP-ribosylation factor-1 (ARF-1), and lipin-1, known to be involved in remodeling liver PL into TG for VLDL maturation and secretion. Lastly, we show that the effects of CNS NPY on key liporegulatory proteins are attenuated by hepatic sympathetic denervation. Conclusions These data support a model in which CNS NPY modulates mediators of hepatic PL remodeling and VLDL maturation to stimulate VLDL-TG secretion that is

  20. Crystallization and preliminary X-ray analysis of the C-terminal fragment of PorM, a subunit of the Porphyromonas gingivalis type IX secretion system.

    Science.gov (United States)

    Stathopulos, Julien; Cambillau, Christian; Cascales, Eric; Roussel, Alain; Leone, Philippe

    2015-01-01

    PorM is a membrane protein involved in the assembly of the type IX secretion system (T9SS) from Porphyromonas gingivalis, a major bacterial pathogen responsible for periodontal disease in humans. The periplasmic domain of PorM was overexpressed in Escherichia coli and purified. A fragment of the purified protein was obtained by limited proteolysis. Crystals of this fragment belonged to the tetragonal space group P4(3)2(1)2. Native and MAD data sets were recorded to 2.85 and 3.1 Å resolution, respectively, using synchrotron radiation.

  1. Measurement of backbone hydrogen-deuterium exchange in the type III secretion system needle protein PrgI by solid-state NMR

    Science.gov (United States)

    Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

    2017-10-01

    In this report we present site-specific measurements of amide hydrogen-deuterium exchange rates in a protein in the solid state phase by MAS NMR. Employing perdeuteration, proton detection and a high external magnetic field we could adopt the highly efficient Relax-EXSY protocol previously developed for liquid state NMR. According to this method, we measured the contribution of hydrogen exchange on apparent 15N longitudinal relaxation rates in samples with differing D2O buffer content. Differences in the apparent T1 times allowed us to derive exchange rates for multiple residues in the type III secretion system needle protein.

  2. Microbiological features and clinical impact of the type VI secretion system (T6SS) in Acinetobacter baumannii isolates causing bacteremia.

    Science.gov (United States)

    Kim, Jungok; Lee, Ji-Young; Lee, Haejeong; Choi, Ji Young; Kim, Dae Hun; Wi, Yu Mi; Peck, Kyong Ran; Ko, Kwan Soo

    2017-10-03

    We investigated the genetic background and microbiological features of T6SS-positive Acinetobacter baumannii isolates and clinical impact of the T6SS in patients with A. baumannii bacteremia. One hundred and 62 A. baumannii isolates from patients with bacteremia in 2 tertiary-care hospitals in Korea were included in this study. Approximately one-third (51/162, 31.5%) of the A. baumannii clinical isolates possessed the hcp gene, and the hcp-positive isolates were found in several genotypes in multilocus sequence typing. The expression and secretion of Hcp protein varied among the clinical isolates. A. baumannii isolates with detectable Hcp secretion (T6SS+) could better outcompete Escherichia coli compared with T6SS- isolates, including hcp-negative and inactivated hcp-positive isolates. In addition, T6SS+ isolates showed higher biofilm-forming activity and better survival in the presence of normal human serum than the T6SS- isolates. T6SS+ isolates were more frequently detected in patients with catheter-related bloodstream infection, haematopoietic stem cell transplant recipients, and patients receiving immunosuppressive agents. However, T6SS was not a prognostic factor for mortality. Our results suggest that the T6SS of A. baumannii is associated with virulence and contributes to infections in immunocompromised patients and those with implanted medical devices.

  3. Development of a quantitative assay amenable for high-throughput screening to target the type II secretion system for new treatments against plant-pathogenic bacteria.

    Science.gov (United States)

    Tran, Nini; Zielke, Ryszard A; Vining, Oliver B; Azevedo, Mark D; Armstrong, Donald J; Banowetz, Gary M; McPhail, Kerry L; Sikora, Aleksandra E

    2013-09-01

    Plant-pathogenic bacteria are the causative agents of diseases in important agricultural crops and ornamental plants. The severe economic burden of these diseases requires seeking new approaches for their control, particularly because phytopathogenic bacteria are often resistant to available treatments. The type II secretion (T2S) system is a key virulence factor used by major groups of phytopathogenic bacteria. The T2S machinery transports many hydrolytic enzymes responsible for degradation of the plant cell wall, thus enabling successful colonization and dissemination of the bacteria in the plant host. The genetic inactivation of the T2S system leads to loss of virulence, which strongly suggests that targeting the T2S could enable new treatments against plant-pathogenic bacteria. Accordingly, we have designed and optimized an assay to identify small-molecule inhibitors of the T2S system. This assay uses a double parametric output: measurement of bacterial growth and the enzymatic activity of cellulase, which is secreted via the T2S pathway in our model organism Dickeya dadantii. The assay was evaluated by screening natural extracts, culture filtrates isolated from rhizosphere bacteria, and a collection of pharmaceutically active compounds in LOPAC(1280). The calculated Z' values of 0.63, 0.63, and 0.58, respectively, strongly suggest that the assay is applicable for a high-throughput screening platform.

  4. Cryptanalysis of 'less short' RSA secret exponents

    NARCIS (Netherlands)

    Verheul, E.R.; Tilborg, van H.C.A.

    1997-01-01

    In some applications of RSA, it is desirable to have a short secret exponent d. Wiener [6], describes a technique to use continued fractions (CF) in a cryptanalytic attack on an RSA cryptosystem having a ‘short’ secret exponent. Let n=p¿·¿q be the modulus of the system. In the typical case that

  5. Expression, purification, crystallization and preliminary crystallographic analysis of MxiH, a subunit of the Shigella flexneri type III secretion system needle

    International Nuclear Information System (INIS)

    Deane, Janet E.; Cordes, Frank S.; Roversi, Pietro; Johnson, Steven; Kenjale, Roma; Picking, William D.; Picking, Wendy L.; Lea, Susan M.; Blocker, Ariel

    2006-01-01

    A monodisperse truncation mutant of MxiH, the subunit of the S. flexneri type III secretion system needle, has been crystallized. SeMet derivatives and a uranyl derivative have undergone preliminary crystallographic analysis. A monodisperse truncation mutant of MxiH, the subunit of the needle from the Shigella flexneri type III secretion system (TTSS), has been overexpressed and purified. Crystals were grown of native and selenomethionine-labelled MxiH CΔ5 and diffraction data were collected to 1.9 Å resolution. The crystals belong to space group C2, with unit-cell parameters a = 183.4, b = 28.1, c = 27.8 Å, β = 96.5°. An anomalous difference Patterson map calculated with the data from the SeMet-labelled crystals revealed a single peak on the Harker section v = 0. Inspection of a uranyl derivative also revealed one peak in the isomorphous difference Patterson map on the Harker section v = 0. Analysis of the self-rotation function indicates the presence of a twofold non-crystallographic symmetry axis approximately along a. The calculated Matthews coefficient is 1.9 Å 3 Da −1 for two molecules per asymmetric unit, corresponding to a solvent content of 33%

  6. Deoxycholate-Enhanced Shigella Virulence Is Regulated by a Rare π-Helix in the Type Three Secretion System Tip Protein IpaD.

    Science.gov (United States)

    Bernard, Abram R; Jessop, T Carson; Kumar, Prashant; Dickenson, Nicholas E

    2017-12-12

    Type three secretion systems (T3SS) are specialized nanomachines that support infection by injecting bacterial proteins directly into host cells. The Shigella T3SS has uniquely evolved to sense environmental levels of the bile salt deoxycholate (DOC) and upregulate virulence in response to DOC. In this study, we describe a rare i + 5 hydrogen bonding secondary structure element (π-helix) within the type three secretion system tip protein IpaD that plays a critical role in DOC-enhanced virulence. Specifically, engineered mutations within the π-helix altered the pathogen's response to DOC, with one mutant construct in particular exhibiting an unprecedented reduction in virulence following DOC exposure. Fluorescence polarization binding assays showed that these altered DOC responses are not the result of differences in affinity between IpaD and DOC, but rather differences in the DOC-dependent T3SS tip maturation resulting from binding of IpaD to translocator/effector protein IpaB. Together, these findings begin to uncover the complex mechanism of DOC-enhanced Shigella virulence while identifying an uncommon structural element that may provide a much needed target for non-antibiotic treatment of Shigella infection.

  7. Expression, purification, crystallization and preliminary crystallographic analysis of MxiH, a subunit of the Shigella flexneri type III secretion system needle

    Energy Technology Data Exchange (ETDEWEB)

    Deane, Janet E.; Cordes, Frank S.; Roversi, Pietro [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Johnson, Steven [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Kenjale, Roma; Picking, William D.; Picking, Wendy L. [Department of Molecular Biosciences, University of Kansas (United States); Lea, Susan M., E-mail: susan.lea@biop.ox.ac.uk [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Blocker, Ariel [Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom)

    2006-03-01

    A monodisperse truncation mutant of MxiH, the subunit of the S. flexneri type III secretion system needle, has been crystallized. SeMet derivatives and a uranyl derivative have undergone preliminary crystallographic analysis. A monodisperse truncation mutant of MxiH, the subunit of the needle from the Shigella flexneri type III secretion system (TTSS), has been overexpressed and purified. Crystals were grown of native and selenomethionine-labelled MxiH{sub CΔ5} and diffraction data were collected to 1.9 Å resolution. The crystals belong to space group C2, with unit-cell parameters a = 183.4, b = 28.1, c = 27.8 Å, β = 96.5°. An anomalous difference Patterson map calculated with the data from the SeMet-labelled crystals revealed a single peak on the Harker section v = 0. Inspection of a uranyl derivative also revealed one peak in the isomorphous difference Patterson map on the Harker section v = 0. Analysis of the self-rotation function indicates the presence of a twofold non-crystallographic symmetry axis approximately along a. The calculated Matthews coefficient is 1.9 Å{sup 3} Da{sup −1} for two molecules per asymmetric unit, corresponding to a solvent content of 33%.

  8. Probabilistic Infinite Secret Sharing

    OpenAIRE

    Csirmaz, László

    2013-01-01

    The study of probabilistic secret sharing schemes using arbitrary probability spaces and possibly infinite number of participants lets us investigate abstract properties of such schemes. It highlights important properties, explains why certain definitions work better than others, connects this topic to other branches of mathematics, and might yield new design paradigms. A probabilistic secret sharing scheme is a joint probability distribution of the shares and the secret together with a colle...

  9. The N-terminus of IpaB provides a potential anchor to the Shigella type III secretion system tip complex protein IpaD

    Science.gov (United States)

    Dickenson, Nicholas E.; Arizmendi, Olivia; Patil, Mrinalini K.; Toth, Ronald T.; Middaugh, C. Russell; Picking, William D.; Picking, Wendy L.

    2014-01-01

    The type III secretion system (T3SS) is an essential virulence factor for Shigella flexneri, providing a conduit through which host-altering effectors are injected directly into a host cell to promote uptake. The type III secretion apparatus (T3SA) is comprised of a basal body, external needle, and regulatory tip complex. The nascent needle is a polymer of MxiH capped by a pentamer of invasion plasmid antigen D (IpaD). Exposure to bile salts (e.g. deoxycholate) causes a conformational change in IpaD and promotes recruitment of IpaB to the needle tip. It has been proposed that IpaB senses contact with host cell membranes, recruiting IpaC and inducing full secretion of T3SS effectors. While the steps of T3SA maturation and their external triggers have been identified, details of specific protein interactions and mechanisms have remained difficult to study due to the hydrophobic nature of the IpaB and IpaC translocator proteins. Here we explored the ability for a series of soluble N-terminal IpaB peptides to interact with IpaD. We found that DOC is required for the interaction and that a region of IpaB between residues 11–27 is required for maximum binding, which was confirmed in vivo. Furthermore, intramolecular FRET measurements indicated that movement of the IpaD distal domain away from the protein core accompanied the binding of IpaB11-226. Together these new findings provide important new insight into the interactions and potential mechanisms that define the maturation of the Shigella T3SA needle tip complex and provide a foundation for further studies probing T3SS activation. PMID:24236510

  10. N-terminus of IpaB provides a potential anchor to the Shigella type III secretion system tip complex protein IpaD.

    Science.gov (United States)

    Dickenson, Nicholas E; Arizmendi, Olivia; Patil, Mrinalini K; Toth, Ronald T; Middaugh, C Russell; Picking, William D; Picking, Wendy L

    2013-12-10

    The type III secretion system (T3SS) is an essential virulence factor for Shigella flexneri , providing a conduit through which host-altering effectors are injected directly into a host cell to promote uptake. The type III secretion apparatus (T3SA) is composed of a basal body, external needle, and regulatory tip complex. The nascent needle is a polymer of MxiH capped by a pentamer of invasion plasmid antigen D (IpaD). Exposure to bile salts (e.g., deoxycholate) causes a conformational change in IpaD and promotes recruitment of IpaB to the needle tip. It has been proposed that IpaB senses contact with host cell membranes, recruiting IpaC and inducing full secretion of T3SS effectors. Although the steps of T3SA maturation and their external triggers have been identified, details of specific protein interactions and mechanisms have remained difficult to study because of the hydrophobic nature of the IpaB and IpaC translocator proteins. Here, we explored the ability for a series of soluble N-terminal IpaB peptides to interact with IpaD. We found that DOC is required for the interaction and that a region of IpaB between residues 11-27 is required for maximum binding, which was confirmed in vivo. Furthermore, intramolecular FRET measurements indicated that movement of the IpaD distal domain away from the protein core accompanied the binding of IpaB11-226. Together, these new findings provide important new insight into the interactions and potential mechanisms that define the maturation of the Shigella T3SA needle tip complex and provide a foundation for further studies probing T3SS activation.

  11. Role of the Genes of Type VI Secretion System in Virulence of Rice Bacterial Brown Stripe Pathogen Acidovorax avenae subsp. avenae Strain RS-2

    Directory of Open Access Journals (Sweden)

    Md. Mahidul Islam Masum

    2017-09-01

    Full Text Available The Type VI secretion system (T6SS is a class of macromolecular machine that is required for the virulence of gram-negative bacteria. However, it is still not clear what the role of T6SS in the virulence of rice bacterial brown stripe pathogen Acidovorax avenae subsp. avenae (Aaa is. The aim of the current study was to investigate the contribution of T6SS in Aaa strain RS2 virulence using insertional deletion mutation and complementation approaches. This strain produced weak virulence but contains a complete T6SS gene cluster based on a genome-wide analysis. Here we compared the virulence-related phenotypes between the wild-type (RS-2 and 25 T6SS mutants, which were constructed using homologous recombination methods. The mutation of 15 T6SS genes significantly reduced bacterial virulence and the secretion of Hcp protein. Additionally, the complemented 7 mutations ΔpppA, ΔclpB, Δhcp, ΔdotU, ΔicmF, ΔimpJ, and ΔimpM caused similar virulence characteristics as RS-2. Moreover, the mutant ΔpppA, ΔclpB, ΔicmF, ΔimpJ and ΔimpM genes caused by a 38.3~56.4% reduction in biofilm formation while the mutants ΔpppA, ΔclpB, ΔicmF and Δhcp resulted in a 37.5~44.6% reduction in motility. All together, these results demonstrate that T6SS play vital roles in the virulence of strain RS-2, which may be partially attributed to the reductions in Hcp secretion, biofilm formation and motility. However, differences in virulence between strain RS-1 and RS-2 suggest that other factors may also be involved in the virulence of Aaa.

  12. Role of the Genes of Type VI Secretion System in Virulence of Rice Bacterial Brown Stripe Pathogen Acidovorax avenae subsp. avenae Strain RS-2.

    Science.gov (United States)

    Masum, Md Mahidul Islam; Yang, Yingzi; Li, Bin; Olaitan, Ogunyemi Solabomi; Chen, Jie; Zhang, Yang; Fang, Yushi; Qiu, Wen; Wang, Yanli; Sun, Guochang

    2017-09-21

    The Type VI secretion system (T6SS) is a class of macromolecular machine that is required for the virulence of gram-negative bacteria. However, it is still not clear what the role of T6SS in the virulence of rice bacterial brown stripe pathogen Acidovorax avenae subsp. avenae (Aaa) is. The aim of the current study was to investigate the contribution of T6SS in Aaa strain RS2 virulence using insertional deletion mutation and complementation approaches. This strain produced weak virulence but contains a complete T6SS gene cluster based on a genome-wide analysis. Here we compared the virulence-related phenotypes between the wild-type (RS-2) and 25 T6SS mutants, which were constructed using homologous recombination methods. The mutation of 15 T6SS genes significantly reduced bacterial virulence and the secretion of Hcp protein. Additionally, the complemented 7 mutations Δ pppA , Δ clpB , Δ hcp , Δ dotU , Δ icmF , Δ impJ , and Δ impM caused similar virulence characteristics as RS-2. Moreover, the mutant Δ pppA , Δ clpB , Δ icmF , Δ impJ and Δ impM genes caused by a 38.3~56.4% reduction in biofilm formation while the mutants Δ pppA , Δ clpB , Δ icmF and Δ hcp resulted in a 37.5~44.6% reduction in motility. All together, these results demonstrate that T6SS play vital roles in the virulence of strain RS-2, which may be partially attributed to the reductions in Hcp secretion, biofilm formation and motility. However, differences in virulence between strain RS-1 and RS-2 suggest that other factors may also be involved in the virulence of Aaa.

  13. Helicobacter pylori Type IV Secretion System and Its Adhesin Subunit, CagL, Mediate Potent Inflammatory Responses in Primary Human Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Mona Tafreshi

    2018-02-01

    Full Text Available The Gram-negative bacterium, Helicobacter pylori, causes chronic gastritis, peptic ulcers, and gastric cancer in humans. Although the gastric epithelium is the primary site of H. pylori colonization, H. pylori can gain access to deeper tissues. Concurring with this notion, H. pylori has been found in the vicinity of endothelial cells in gastric submucosa. Endothelial cells play crucial roles in innate immune response, wound healing and tumorigenesis. This study examines the molecular mechanisms by which H. pylori interacts with and triggers inflammatory responses in endothelial cells. We observed that H. pylori infection of primary human endothelial cells stimulated secretion of the key inflammatory cytokines, interleukin-6 (IL-6 and interleukin-8 (IL-8. In particular, IL-8, a potent chemokine and angiogenic factor, was secreted by H. pylori-infected endothelial cells to levels ~10- to 20-fold higher than that typically observed in H. pylori-infected gastric epithelial cells. These inflammatory responses were triggered by the H. pylori type IV secretion system (T4SS and the T4SS-associated adhesin CagL, but not the translocation substrate CagA. Moreover, in contrast to integrin α5β1 playing an essential role in IL-8 induction by H. pylori upon infection of gastric epithelial cells, both integrin α5β1 and integrin αvβ3 were dispensable for IL-8 induction in H. pylori-infected endothelial cells. However, epidermal growth factor receptor (EGFR is crucial for mediating the potent H. pylori-induced IL-8 response in endothelial cells. This study reveals a novel mechanism by which the H. pylori T4SS and its adhesin subunit, CagL, may contribute to H. pylori pathogenesis by stimulating the endothelial innate immune responses, while highlighting EGFR as a potential therapeutic target for controlling H. pylori-induced inflammation.

  14. The Toolbox for Uncovering the Functions of Legionella Dot/Icm Type IVb Secretion System Effectors: Current State and Future Directions

    Directory of Open Access Journals (Sweden)

    Gunnar N. Schroeder

    2018-01-01

    Full Text Available The defective in organelle trafficking/intracellular multiplication (Dot/Icm Type IVb secretion system (T4SS is the essential virulence factor for the intracellular life style and pathogenicity of Legionella species. Screens demonstrated that an individual L. pneumophila strain can use the Dot/Icm T4SS to translocate an unprecedented number of more than 300 proteins into host cells, where these, so called Icm/Dot-translocated substrates (IDTS or effectors, manipulate host cell functions to the benefit of the bacteria. Bioinformatic analysis of the pan-genus genome predicts at least 608 orthologous groups of putative effectors. Deciphering the function of these effectors is key to understanding Legionella pathogenesis; however, the analysis is challenging. Substantial functional redundancy renders classical, phenotypic screening of single gene deletion mutants mostly ineffective. Here, I review experimental approaches that were successfully used to identify, validate and functionally characterize T4SS effectors and highlight new methods, which promise to facilitate unlocking the secrets of Legionella's extraordinary weapons arsenal.

  15. Gamma irradiation effects on human growth hormone producing pituitary adenoma tissue. An analysis of morphology and hormone secretion in an in vitro model system

    Energy Technology Data Exchange (ETDEWEB)

    Anniko, M [Karolinska sjukhuset, Stockholm (Sweden). Dept. of Oto-Rhino-Laryngology; Arndt, J [Karolinska sjukhuset, Stockholm (Sweden). Dept. of Radiophysics, Radiumhemmet; Raehn, T [Karolinska sjukhuset, Stockholm (Sweden). Dept. of Neurosurgery; Werner, S [Karolinska sjukhuset, Stockholm (Sweden). Dept. of Endocrinology

    1982-01-01

    Irradiation-induced effects on pituitary cell morphology and secretion of growth hormone (GH) and prolactin (PRL) have been analysed using an in vitro system. Specimens for organ culture were were obtained from three patients with pituitary tumours causing acromegaly but with different clinical activity of disease. Specimens were followed in vitro 1 h - 6 days after single-dose gamma irradiation (/sup 60/Co) with 70 100 and 150 Gy, respectively. These doses are used in clinical work for the stereotactic radiosuregery of pituitary adenomas. Considerable fluctuations in hormone secretion/release occurred during the first 24h after irradiation. All three tumours showed individual differences concern ing irradiation-induced morphological damage. Only a minor variation occurred between specimens from the same tumour. An individual sensitivity to irradiation of pituitary tumours in vitro is documented. The great number of surviving pituitary tumour cells one week after irradiation-many with an intact ultrastructure and containing hormone granules-indicated an initial high degree of radioresistance.

  16. VE-cadherin cleavage by LasB protease from Pseudomonas aeruginosa facilitates type III secretion system toxicity in endothelial cells.

    Directory of Open Access Journals (Sweden)

    Guillaume Golovkine

    2014-03-01

    Full Text Available Infection of the vascular system by Pseudomonas aeruginosa (Pa occurs during bacterial dissemination in the body or in blood-borne infections. Type 3 secretion system (T3SS toxins from Pa induce a massive retraction when injected into endothelial cells. Here, we addressed the role of type 2 secretion system (T2SS effectors in this process. Mutants with an inactive T2SS were much less effective than wild-type strains at inducing cell retraction. Furthermore, secretomes from wild-types were sufficient to trigger cell-cell junction opening when applied to cells, while T2SS-inactivated mutants had minimal activity. Intoxication was associated with decreased levels of vascular endothelial (VE-cadherin, a homophilic adhesive protein located at endothelial cell-cell junctions. During the process, the protein was cleaved in the middle of its extracellular domain (positions 335 and 349. VE-cadherin attrition was T3SS-independent but T2SS-dependent. Interestingly, the epithelial (E-cadherin was unaffected by T2SS effectors, indicating that this mechanism is specific to endothelial cells. We showed that one of the T2SS effectors, the protease LasB, directly affected VE-cadherin proteolysis, hence promoting cell-cell junction disruption. Furthermore, mouse infection with Pa to induce acute pneumonia lead to significant decreases in lung VE-cadherin levels, whereas the decrease was minimal with T2SS-inactivated or LasB-deleted mutant strains. We conclude that the T2SS plays a pivotal role during Pa infection of the vascular system by breaching the endothelial barrier, and propose a model in which the T2SS and the T3SS cooperate to intoxicate endothelial cells.

  17. Dynamic quantum secret sharing

    International Nuclear Information System (INIS)

    Jia, Heng-Yue; Wen, Qiao-Yan; Gao, Fei; Qin, Su-Juan; Guo, Fen-Zhuo

    2012-01-01

    In this Letter we consider quantum secret sharing (QSS) between a sender and a dynamic agent group, called dynamic quantum secret sharing (DQSS). In the DQSS, the change of the agent group is allowable during the procedure of sharing classical and quantum information. Two DQSS schemes are proposed based on a special kind of entangled state, starlike cluster states. Without redistributing all the shares, the changed agent group can reconstruct the sender's secret by their cooperation. Compared with the previous quantum secret sharing scheme, our schemes are more flexible and suitable for practical applications. -- Highlights: ► We consider quantum secret sharing between a sender and a dynamic agent group, called dynamic quantum secret sharing (DQSS). ► In the DQSS, the change of the agent group is allowable during the procedure of sharing classical and quantum information. ► Two DQSS schemes are proposed based on a special kind of entangled state, starlike cluster states. ► Without redistributing all the shares, the changed agent group can reconstruct the sender's secret by their cooperation. ► Compared with the previous quantum secret sharing scheme, our schemes are more flexible and suitable for practical applications.

  18. Type III secretion system and virulence markers highlight similarities and differences between human- and plant-associated pseudomonads related to Pseudomonas fluorescens and P. putida.

    Science.gov (United States)

    Mazurier, Sylvie; Merieau, Annabelle; Bergeau, Dorian; Decoin, Victorien; Sperandio, Daniel; Crépin, Alexandre; Barbey, Corinne; Jeannot, Katy; Vicré-Gibouin, Maïté; Plésiat, Patrick; Lemanceau, Philippe; Latour, Xavier

    2015-04-01

    Pseudomonas fluorescens is commonly considered a saprophytic rhizobacterium devoid of pathogenic potential. Nevertheless, the recurrent isolation of strains from clinical human cases could indicate the emergence of novel strains originating from the rhizosphere reservoir, which could be particularly resistant to the immune system and clinical treatment. The importance of type three secretion systems (T3SSs) in the related Pseudomonas aeruginosa nosocomial species and the occurrence of this secretion system in plant-associated P. fluorescens raise the question of whether clinical isolates may also harbor T3SSs. In this study, isolates associated with clinical infections and identified in hospitals as belonging to P. fluorescens were compared with fluorescent pseudomonads harboring T3SSs isolated from plants. Bacterial isolates were tested for (i) their genetic relationships based on their 16S rRNA phylogeny, (ii) the presence of T3SS genes by PCR, and (iii) their infectious potential on animals and plants under environmental or physiological temperature conditions. Two groups of bacteria were delineated among the clinical isolates. The first group encompassed thermotolerant (41°C) isolates from patients suffering from blood infections; these isolates were finally found to not belong to P. fluorescens but were closely related and harbored highly conserved T3SS genes belonging to the Ysc-T3SS family, like the T3SSs from P. aeruginosa. The second group encompassed isolates from patients suffering from cystic fibrosis; these isolates belonged to P. fluorescens and harbored T3SS genes belonging to the Hrp1-T3SS family found commonly in plant-associated P. fluorescens. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  19. Wolbachia lipoproteins: abundance, localisation and serology of Wolbachia peptidoglycan associated lipoprotein and the Type IV Secretion System component, VirB6 from Brugia malayi and Aedes albopictus.

    Science.gov (United States)

    Voronin, Denis; Guimarães, Ana F; Molyneux, Gemma R; Johnston, Kelly L; Ford, Louise; Taylor, Mark J

    2014-10-06

    Lipoproteins are the major agonists of Wolbachia-dependent inflammatory pathogenesis in filariasis and a validated target for drug discovery. Here we characterise the abundance, localisation and serology of the Wolbachia lipoproteins: Wolbachia peptidoglycan associated lipoprotein and the Type IV Secretion System component, VirB6. We used proteomics to confirm lipoprotein presence and relative abundance; fractionation, immunoblotting and confocal and electron immuno-microscopy for localisation and ELISA for serological analysis. Proteomic analysis of Brugia malayi adult female protein extracts confirmed the presence of two lipoproteins, previously predicted through bioinformatics: Wolbachia peptidoglycan associated lipoprotein (wBmPAL) and the Type IV Secretion System component, VirB6 (wBmVirB6). wBmPAL was among the most abundant Wolbachia proteins present in an extract of adult female worms with wBmVirB6 only detected at a much lower abundance. This differential abundance was reflected in the immunogold-labelling, which showed wBmPAL localised at numerous sites within the bacterial membranes, whereas wBmVirB6 was present as a single cluster on each bacterial cell and also located within the bacterial membranes. Immunoblotting of fractionated extracts confirmed the localisation of wBmPAL to membranes and its absence from cytosolic fractions of C6/36 mosquito cells infected with wAlbB. In whole worm mounts, antibody labelling of both lipoproteins were associated with Wolbachia. Serological analysis showed that both proteins were immunogenic and raised antibody responses in the majority of individuals infected with Wuchereria bancrofti. Two Wolbachia lipoproteins, wBmPAL and wBmVirB6, are present in extracts of Brugia malayi with wBmPAL among the most abundant of Wolbachia proteins. Both lipoproteins localised to bacterial membranes with wBmVirB6 present as a single cluster suggesting a single Type IV Secretory System on each Wolbachia cell.

  20. Camelid nanobodies used as crystallization chaperones for different constructs of PorM, a component of the type IX secretion system from Porphyromonas gingivalis.

    Science.gov (United States)

    Duhoo, Yoan; Roche, Jennifer; Trinh, Thi Trang Nhung; Desmyter, Aline; Gaubert, Anaïs; Kellenberger, Christine; Cambillau, Christian; Roussel, Alain; Leone, Philippe

    2017-05-01

    PorM is a membrane protein that is involved in the assembly of the type IX secretion system (T9SS) in Porphyromonas gingivalis, a major bacterial pathogen that is responsible for periodontal disease in humans. In the context of structural studies of PorM to better understand T9SS assembly, four camelid nanobodies were selected, produced and purified, and their specific interaction with the N-terminal or C-terminal part of the periplasmic domain of PorM was investigated. Diffracting crystals were also obtained, and the structures of the four nanobodies were solved by molecular replacement. Furthermore, two nanobodies were used as crystallization chaperones and turned out to be valuable tools in the structure-determination process of the periplasmic domain of PorM.

  1. Detection of the type III secretion system and its phylogenetic and symbiotic characterization in peanut bradyrhizobia isolated from Guangdong Province, China.

    Science.gov (United States)

    Ruan, Huaqin; Hu, Meijuan; Chen, Jingyu; Li, Xue; Li, Ting; Lai, Yongxiu; Wang, En Tao; Gu, Jun

    2018-04-08

    The distribution of rhcRST and rhcJ-C1 fragments located in different loci of the type III secretion system (T3SS) gene cluster in the peanut-nodulating bradyrhizobia isolated from Guangdong Province, China was investigated by PCR-based sequencing. T3SS was detected in approximately one-third of the peanut bradyrhizobial strains and the T3SS-harboring strains belonging to different Bradyrhizobium genomic species. Diverse T3SS groups corresponding to different symbiotic gene types were defined among the 23 T3SS-harboring strains. The same or similar T3SS genes were detected in different genospecies, indicating that interspecies horizontal transfer of symbiotic genes had occurred in the Bradyrhizobium genus. Copyright © 2018. Published by Elsevier GmbH.

  2. Evaluation of immunogenicity and protective efficacy of orally delivered Shigella type III secretion system proteins IpaB and IpaD.

    Science.gov (United States)

    Heine, Shannon J; Diaz-McNair, Jovita; Martinez-Becerra, Francisco J; Choudhari, Shyamal P; Clements, John D; Picking, Wendy L; Pasetti, Marcela F

    2013-06-19

    Shigella spp. are food- and water-borne pathogens that cause shigellosis, a severe diarrheal and dysenteric disease that is associated with a high morbidity and mortality in resource-poor countries. No licensed vaccine is available to prevent shigellosis. We have recently demonstrated that Shigella invasion plasmid antigens (Ipas), IpaB and IpaD, which are components of the bacterial type III secretion system (TTSS), can prevent infection in a mouse model of intranasal immunization and lethal pulmonary challenge. Because they are conserved across Shigella spp. and highly immunogenic, these proteins are excellent candidates for a cross-protective vaccine. Ideally, such a vaccine could be administered to humans orally to induce mucosal and systemic immunity. In this study, we investigated the immunogenicity and protective efficacy of Shigella IpaB and IpaD administered orally with a double mutant of the Escherichia coli heat labile toxin (dmLT) as a mucosal adjuvant. We characterized the immune responses induced by oral vs. intranasal immunization and the protective efficacy using a mouse pulmonary infection model. Serum IgG and fecal IgA against IpaB were induced after oral immunization. These responses, however, were lower than those obtained after intranasal immunization despite a 100-fold dosage increase. The level of protection induced by oral immunization with IpaB and IpaD was 40%, while intranasal immunization resulted in 90% protective efficacy. IpaB- and IpaD-specific IgA antibody-secreting cells in the lungs and spleen and T-cell-derived IL-2, IL-5, IL-17 and IL-10 were associated with protection. These results demonstrate the immunogenicity of orally administered IpaB and IpaD and support further studies in humans. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Expression, limited proteolysis and preliminary crystallographic analysis of IpaD, a component of the Shigella flexneri type III secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Steven [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Roversi, Pietro [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Espina, Marianela [Department of Molecular Biosciences, University of Kansas (United States); Deane, Janet E. [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Birket, Susan; Picking, William D. [Department of Molecular Biosciences, University of Kansas (United States); Blocker, Ariel [Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Picking, Wendy L. [Department of Molecular Biosciences, University of Kansas (United States); Lea, Susan M., E-mail: susan.lea@path.ox.ac.uk [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Sir William Dunn School of Pathology, University of Oxford (United Kingdom)

    2006-09-01

    IpaD, the putative needle-tip protein of the S. flexneri type III secretion system, has been crystallized in a variety of crystal forms using in-drop proteolysis. Native and selenomethionine-labelled data collection and preliminary analyses are reported. IpaD, the putative needle-tip protein of the Shigella flexneri type III secretion system, has been overexpressed and purified. Crystals were grown of the native protein in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 55.9, b = 100.7, c = 112.0 Å, and data were collected to 2.9 Å resolution. Analysis of the native Patterson map revealed a peak at 50% of the origin on the Harker section v = 0.5, suggesting twofold non-crystallographic symmetry parallel to the b crystallographic axis. As attempts to derivatize or grow selenomethionine-labelled protein crystals failed, in-drop proteolysis was used to produce new crystal forms. A trace amount of subtilisin Carlsberg was added to IpaD before sparse-matrix screening, resulting in the production of several new crystal forms. This approach produced SeMet-labelled crystals and diffraction data were collected to 3.2 Å resolution. The SeMet crystals belong to space group C2, with unit-cell parameters a = 139.4, b = 45.0, c = 99.5 Å, β = 107.9°. An anomalous difference Patterson map revealed peaks on the Harker section v = 0, while the self-rotation function indicates the presence of a twofold noncrystallographic symmetry axis, which is consistent with two molecules per asymmetric unit.

  4. Expression, limited proteolysis and preliminary crystallographic analysis of IpaD, a component of the Shigella flexneri type III secretion system

    International Nuclear Information System (INIS)

    Johnson, Steven; Roversi, Pietro; Espina, Marianela; Deane, Janet E.; Birket, Susan; Picking, William D.; Blocker, Ariel; Picking, Wendy L.; Lea, Susan M.

    2006-01-01

    IpaD, the putative needle-tip protein of the S. flexneri type III secretion system, has been crystallized in a variety of crystal forms using in-drop proteolysis. Native and selenomethionine-labelled data collection and preliminary analyses are reported. IpaD, the putative needle-tip protein of the Shigella flexneri type III secretion system, has been overexpressed and purified. Crystals were grown of the native protein in space group P2 1 2 1 2 1 , with unit-cell parameters a = 55.9, b = 100.7, c = 112.0 Å, and data were collected to 2.9 Å resolution. Analysis of the native Patterson map revealed a peak at 50% of the origin on the Harker section v = 0.5, suggesting twofold non-crystallographic symmetry parallel to the b crystallographic axis. As attempts to derivatize or grow selenomethionine-labelled protein crystals failed, in-drop proteolysis was used to produce new crystal forms. A trace amount of subtilisin Carlsberg was added to IpaD before sparse-matrix screening, resulting in the production of several new crystal forms. This approach produced SeMet-labelled crystals and diffraction data were collected to 3.2 Å resolution. The SeMet crystals belong to space group C2, with unit-cell parameters a = 139.4, b = 45.0, c = 99.5 Å, β = 107.9°. An anomalous difference Patterson map revealed peaks on the Harker section v = 0, while the self-rotation function indicates the presence of a twofold noncrystallographic symmetry axis, which is consistent with two molecules per asymmetric unit

  5. Expression, purification, crystallization and preliminary crystallographic analysis of BipD, a component of the Burkholderia pseudomallei type III secretion system

    International Nuclear Information System (INIS)

    Roversi, Pietro; Johnson, Steven; Field, Terry; Deane, Janet E.; Galyov, Edouard E.; Lea, Susan M.

    2006-01-01

    A construct consisting of residues 10–310 of mature BipD, a component of the B. pseudomallei type III secretion system, has been crystallized. Native BipD crystals and SeMet and K 2 PtCl 4 derivative crystals have undergone preliminary crystallographic analysis. A construct consisting of residues 10–310 of BipD, a component of the Burkholderia pseudomallei type III secretion system (T3SS), has been overexpressed as a GST fusion, cleaved from the GST tag and purified. Crystals were grown of native and selenomethionine-labelled BipD. The crystals grow in two different polymorphs from the same condition. The first polymorph belongs to space group C222, with unit-cell parameters a = 103.98, b = 122.79, c = 49.17 Å, a calculated Matthews coefficient of 2.4 Å 3 Da −1 (47% solvent content) and one molecule per asymmetric unit. The second polymorph belongs to space group P2 1 2 1 2, with unit-cell parameters a = 136.47, b = 89.84, c = 50.15 Å, and a calculated Matthews coefficient of 2.3 Å 3 Da −1 (45% solvent content) for two molecules per asymmetric unit (analysis of the self-rotation function indicates the presence of a weak twofold non-crystallographic symmetry axis in this P2 1 2 1 2 form). The native crystals of both forms give diffraction data to 2.7 Å resolution, while the SeMet-labelled P2 1 2 1 2 crystals diffract to 3.3 Å resolution. A K 2 PtCl 4 derivative of the P2 1 2 1 2 form was also obtained and data were collected to 2.7 Å with radiation of wavelength λ = 0.933 Å. The Pt-derivative anomalous difference Patterson map revealed two self-peaks on the Harker sections

  6. Incretin secretion: direct mechanisms

    DEFF Research Database (Denmark)

    Balk-Møller, Emilie; Holst, Jens Juul; Kuhre, Rune Ehrenreich

    2014-01-01

    The incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are secreted from gastro-intestinal K- and L-cells, respectively, and play an important role in post-prandial blood glucose regulation. They do this by direct stimulation of the pancreatic β...... enzyme responsible for incretin degradation (dipeptidyl peptidase-4) is inhibited (drugs are already on the market) while the secretion of endogenous GLP-1 secretion is stimulated at the same time may prove particularly rewarding. In this section we review current knowledge on the mechanisms for direct...

  7. Secreted factors as synaptic organizers.

    Science.gov (United States)

    Johnson-Venkatesh, Erin M; Umemori, Hisashi

    2010-07-01

    A critical step in synaptic development is the differentiation of presynaptic and postsynaptic compartments. This complex process is regulated by a variety of secreted factors that serve as synaptic organizers. Specifically, fibroblast growth factors, Wnts, neurotrophic factors and various other intercellular signaling molecules are proposed to regulate presynaptic and/or postsynaptic differentiation. Many of these factors appear to function at both the neuromuscular junction and in the central nervous system, although the specific function of the molecules differs between the two. Here we review secreted molecules that organize the synaptic compartments and discuss how these molecules shape synaptic development, focusing on mammalian in vivo systems. Their critical role in shaping a functional neural circuit is underscored by their possible link to a wide range of neurological and psychiatric disorders both in animal models and by mutations identified in human patients. © The Authors (2010). Journal Compilation © Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  8. Bartonella henselae trimeric autotransporter adhesin BadA expression interferes with effector translocation by the VirB/D4 type IV secretion system.

    Science.gov (United States)

    Lu, Yun-Yueh; Franz, Bettina; Truttmann, Matthias C; Riess, Tanja; Gay-Fraret, Jérémie; Faustmann, Marco; Kempf, Volkhard A J; Dehio, Christoph

    2013-05-01

    The Gram-negative, zoonotic pathogen Bartonella henselae is the aetiological agent of cat scratch disease, bacillary angiomatosis and peliosis hepatis in humans. Two pathogenicity factors of B. henselae - each displaying multiple functions in host cell interaction - have been characterized in greater detail: the trimeric autotransporter Bartonella adhesin A (BadA) and the type IV secretion system VirB/D4 (VirB/D4 T4SS). BadA mediates, e.g. binding to fibronectin (Fn), adherence to endothelial cells (ECs) and secretion of vascular endothelial growth factor (VEGF). VirB/D4 translocates several Bartonella effector proteins (Beps) into the cytoplasm of infected ECs, resulting, e.g. in uptake of bacterial aggregates via the invasome structure, inhibition of apoptosis and activation of a proangiogenic phenotype. Despite this knowledge of the individual activities of BadA or VirB/D4 it is unknown whether these major virulence factors affect each other in their specific activities. In this study, expression and function of BadA and VirB/D4 were analysed in a variety of clinical B. henselae isolates. Data revealed that most isolates have lost expression of either BadA or VirB/D4 during in vitro passages. However, the phenotypic effects of coexpression of both virulence factors was studied in one clinical isolate that was found to stably coexpress BadA and VirB/D4, as well as by ectopic expression of BadA in a strain expressing VirB/D4 but not BadA. BadA, which forms a dense layer on the bacterial surface, negatively affected VirB/D4-dependent Bep translocation and invasome formation by likely preventing close contact between the bacterial cell envelope and the host cell membrane. In contrast, BadA-dependent Fn binding, adhesion to ECs and VEGF secretion were not affected by a functional VirB/D4 T4SS. The obtained data imply that the essential virulence factors BadA and VirB/D4 are likely differentially expressed during different stages of the infection cycle of

  9. The YsrS Paralog DygS Has the Capacity To Activate Expression of the Yersinia enterocolitica Ysa Type III Secretion System.

    Science.gov (United States)

    Walker, Kimberly A; Griggs, Lauren A; Obrist, Markus; Bode, Addys; Summers, R Patrick; Miller, Virginia L

    2016-06-15

    The Yersinia enterocolitica Ysa type III secretion system (T3SS) is associated with intracellular survival, and, like other characterized T3SSs, it is tightly controlled. Expression of the ysa genes is only detected following growth at low temperatures (26°C) and in high concentrations of sodium chloride (290 mM) in the medium. The YsrSTR phosphorelay (PR) system is required for ysa expression and likely responds to NaCl. During our investigations into the Ysr PR system, we discovered that genes YE3578 and YE3579 are remarkably similar to ysrR and ysrS, respectively, and are probably a consequence of a gene duplication event. The amino acid differences between YE3578 and ysrR are primarily clustered into two short regions. The differences between YE3579 and ysrS are nearly all located in the periplasmic sensing domain; the cytoplasmic domains are 98% identical. We investigated whether these paralogs were capable of activating ysa gene expression. We found that the sensor paralog, named DygS, is capable of compensating for loss of ysrS, but the response regulator paralog, DygR, cannot complement a ysrR gene deletion. In addition, YsrR, but not DygR, interacts with the histidine phosphorelay protein YsrT. Thus, DygS likely activates ysa gene expression in response to a signal other than NaCl and provides an example of a phosphorelay system in which two sensor kinases feed into the same regulatory pathway. All organisms need mechanisms to promote survival in changing environments. Prokaryotic phosphorelay systems are minimally comprised of a histidine kinase (HK) that senses an extracellular stimulus and a response regulator (RR) but can contain three or more proteins. Through gene duplication, a unique hybrid HK was created. We show that, while the hybrid appears to retain all of the phosphorelay functions, it responds to a different signal than the original. Both HKs transmit the signal to the same RR, which activates a promoter that transcribes a set of genes

  10. Secret quality of love.

    Science.gov (United States)

    Strachan-Hall, Elaine

    2016-09-01

    Many of us can recite three Donabedian dimensions of the quality of care of structure, process and outcome. Recently, I was introduced to another of Avedis Donabedian's quotes about the 'secret quality of love'.

  11. Six secrets of champagne

    Science.gov (United States)

    Liger-Belair, Gérard

    2015-12-01

    Popping open a bottle of champagne is one of life's great delights, but how much do you really know about the science behind this greatest of wines? Gérard Liger-Belair reveals his six favourite champagne secrets.

  12. Impaired endogenous nighttime melatonin secretion relates to intrarenal renin-angiotensin system activation and renal damage in patients with chronic kidney disease.

    Science.gov (United States)

    Ishigaki, Sayaka; Ohashi, Naro; Isobe, Shinsuke; Tsuji, Naoko; Iwakura, Takamasa; Ono, Masafumi; Sakao, Yukitoshi; Tsuji, Takayuki; Kato, Akihiko; Miyajima, Hiroaki; Yasuda, Hideo

    2016-12-01

    Activation of the intrarenal renin-angiotensin system (RAS) plays a critical role in the pathophysiology of chronic kidney disease (CKD) and hypertension. The circadian rhythm of intrarenal RAS activation leads to renal damage and hypertension, which are associated with diurnal blood pressure (BP) variation. The activation of intrarenal RAS following reactive oxygen species (ROS) activation, sympathetic hyperactivity and nitric oxide (NO) inhibition leads to the development of renal damage. Melatonin is a hormone regulating the circadian rhythm, and has multiple functions such as anti-oxidant and anti-adrenergic effects and enhancement of NO bioavailability. Nocturnal melatonin concentrations are lower in CKD patients. However, it is not known if impaired endogenous melatonin secretion is related to BP, intrarenal RAS, or renal damage in CKD patients. We recruited 53 CKD patients and conducted 24-h ambulatory BP monitoring. urine was collected during the daytime and nighttime. We investigated the relationship among the melatonin metabolite urinary 6-sulphatoxymelatonin (U-aMT6s), BP, renal function, urinary angiotensinogen (U-AGT), and urinary albumin (U-Alb). Patients' U-aMT6s levels were significantly and negatively correlated with clinical parameters such as renal function, systolic BP, U-AGT, and U-Alb, during both day and night. Multiple regression analyses for U-aMT6s levels were performed using age, gender, renal function, and each parameter (BPs, U-AGT or U-Alb), at daytime and nighttime. U-aMT6s levels were significantly associated with U-AGT (β = -0.31, p = 0.044) and U-Alb (β = -0.25, p = 0.025) only at night. Impaired nighttime melatonin secretion may be associated with nighttime intrarenal RAS activation and renal damage in CKD patients.

  13. An optimal set of features for predicting type IV secretion system effector proteins for a subset of species based on a multi-level feature selection approach.

    Directory of Open Access Journals (Sweden)

    Zhila Esna Ashari

    Full Text Available Type IV secretion systems (T4SS are multi-protein complexes in a number of bacterial pathogens that can translocate proteins and DNA to the host. Most T4SSs function in conjugation and translocate DNA; however, approximately 13% function to secrete proteins, delivering effector proteins into the cytosol of eukaryotic host cells. Upon entry, these effectors manipulate the host cell's machinery for their own benefit, which can result in serious illness or death of the host. For this reason recognition of T4SS effectors has become an important subject. Much previous work has focused on verifying effectors experimentally, a costly endeavor in terms of money, time, and effort. Having good predictions for effectors will help to focus experimental validations and decrease testing costs. In recent years, several scoring and machine learning-based methods have been suggested for the purpose of predicting T4SS effector proteins. These methods have used different sets of features for prediction, and their predictions have been inconsistent. In this paper, an optimal set of features is presented for predicting T4SS effector proteins using a statistical approach. A thorough literature search was performed to find features that have been proposed. Feature values were calculated for datasets of known effectors and non-effectors for T4SS-containing pathogens for four genera with a sufficient number of known effectors, Legionella pneumophila, Coxiella burnetii, Brucella spp, and Bartonella spp. The features were ranked, and less important features were filtered out. Correlations between remaining features were removed, and dimensional reduction was accomplished using principal component analysis and factor analysis. Finally, the optimal features for each pathogen were chosen by building logistic regression models and evaluating each model. The results based on evaluation of our logistic regression models confirm the effectiveness of our four optimal sets of

  14. Postreplication Roles of the Brucella VirB Type IV Secretion System Uncovered via Conditional Expression of the VirB11 ATPase

    Directory of Open Access Journals (Sweden)

    Erin P. Smith

    2016-11-01

    Full Text Available Brucella abortus, the bacterial agent of the worldwide zoonosis brucellosis, primarily infects host phagocytes, where it undergoes an intracellular cycle within a dedicated membrane-bound vacuole, the Brucella-containing vacuole (BCV. Initially of endosomal origin (eBCV, BCVs are remodeled into replication-permissive organelles (rBCV derived from the host endoplasmic reticulum, a process that requires modulation of host secretory functions via delivery of effector proteins by the Brucella VirB type IV secretion system (T4SS. Following replication, rBCVs are converted into autophagic vacuoles (aBCVs that facilitate bacterial egress and subsequent infections, arguing that the bacterium sequentially manipulates multiple cellular pathways to complete its cycle. The VirB T4SS is essential for rBCV biogenesis, as VirB-deficient mutants are stalled in eBCVs and cannot mediate rBCV biogenesis. This has precluded analysis of whether the VirB apparatus also drives subsequent stages of the Brucella intracellular cycle. To address this issue, we have generated a B. abortus strain in which VirB T4SS function is conditionally controlled via anhydrotetracycline (ATc-dependent complementation of a deletion of the virB11 gene encoding the VirB11 ATPase. We show in murine bone marrow-derived macrophages (BMMs that early VirB production is essential for optimal rBCV biogenesis and bacterial replication. Transient expression of virB11 prior to infection was sufficient to mediate normal rBCV biogenesis and bacterial replication but led to T4SS inactivation and decreased aBCV formation and bacterial release, indicating that these postreplication stages are also T4SS dependent. Hence, our findings support the hypothesis of additional, postreplication roles of type IV secretion in the Brucella intracellular cycle.

  15. Structural and Biochemical Characterization of Spa47 Provides Mechanistic Insight into Type III Secretion System ATPase Activation and Shigella Virulence Regulation.

    Science.gov (United States)

    Burgess, Jamie L; Burgess, R Alan; Morales, Yalemi; Bouvang, Jenna M; Johnson, Sean J; Dickenson, Nicholas E

    2016-12-09

    Like many Gram-negative pathogens, Shigella rely on a complex type III secretion system (T3SS) to inject effector proteins into host cells, take over host functions, and ultimately establish infection. Despite these critical roles, the energetics and regulatory mechanisms controlling the T3SS and pathogen virulence remain largely unclear. In this study, we present a series of high resolution crystal structures of Spa47 and use the structures to model an activated Spa47 oligomer, finding that ATP hydrolysis may be supported by specific side chain contributions from adjacent protomers within the complex. Follow-up mutagenesis experiments targeting the predicted active site residues validate the oligomeric model and determined that each of the tested residues are essential for Spa47 ATPase activity, although they are not directly responsible for stable oligomer formation. Although N-terminal domain truncation was necessary for crystal formation, it resulted in strictly monomeric Spa47 that is unable to hydrolyze ATP, despite maintaining the canonical ATPase core structure and active site residues. Coupled with studies of ATPase inactive full-length Spa47 point mutants, we find that Spa47 oligomerization and ATP hydrolysis are needed for complete T3SS apparatus formation, a proper translocator secretion profile, and Shigella virulence. This work represents the first structure-function characterization of Spa47, uniquely complementing the multitude of included Shigella T3SS phenotype assays and providing a more complete understanding of T3SS ATPase-mediated pathogen virulence. Additionally, these findings provide a strong platform for follow-up studies evaluating regulation of Spa47 oligomerization in vivo as a much needed means of treating and perhaps preventing shigellosis. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Structural and Biochemical Characterization of Spa47 Provides Mechanistic Insight into Type III Secretion System ATPase Activation and Shigella Virulence Regulation*

    Science.gov (United States)

    Burgess, Jamie L.; Burgess, R. Alan; Morales, Yalemi; Bouvang, Jenna M.; Johnson, Sean J.; Dickenson, Nicholas E.

    2016-01-01

    Like many Gram-negative pathogens, Shigella rely on a complex type III secretion system (T3SS) to inject effector proteins into host cells, take over host functions, and ultimately establish infection. Despite these critical roles, the energetics and regulatory mechanisms controlling the T3SS and pathogen virulence remain largely unclear. In this study, we present a series of high resolution crystal structures of Spa47 and use the structures to model an activated Spa47 oligomer, finding that ATP hydrolysis may be supported by specific side chain contributions from adjacent protomers within the complex. Follow-up mutagenesis experiments targeting the predicted active site residues validate the oligomeric model and determined that each of the tested residues are essential for Spa47 ATPase activity, although they are not directly responsible for stable oligomer formation. Although N-terminal domain truncation was necessary for crystal formation, it resulted in strictly monomeric Spa47 that is unable to hydrolyze ATP, despite maintaining the canonical ATPase core structure and active site residues. Coupled with studies of ATPase inactive full-length Spa47 point mutants, we find that Spa47 oligomerization and ATP hydrolysis are needed for complete T3SS apparatus formation, a proper translocator secretion profile, and Shigella virulence. This work represents the first structure-function characterization of Spa47, uniquely complementing the multitude of included Shigella T3SS phenotype assays and providing a more complete understanding of T3SS ATPase-mediated pathogen virulence. Additionally, these findings provide a strong platform for follow-up studies evaluating regulation of Spa47 oligomerization in vivo as a much needed means of treating and perhaps preventing shigellosis. PMID:27770024

  17. Transporter-mediated biofuel secretion.

    Science.gov (United States)

    Doshi, Rupak; Nguyen, Tuan; Chang, Geoffrey

    2013-05-07

    Engineering microorganisms to produce biofuels is currently among the most promising strategies in renewable energy. However, harvesting these organisms for extracting biofuels is energy- and cost-intensive, limiting the commercial feasibility of large-scale production. Here, we demonstrate the use of a class of transport proteins of pharmacological interest to circumvent the need to harvest biomass during biofuel production. We show that membrane-embedded transporters, better known to efflux lipids and drugs, can be used to mediate the secretion of intracellularly synthesized model isoprenoid biofuel compounds to the extracellular milieu. Transporter-mediated biofuel secretion sustainably maintained an approximate three- to fivefold boost in biofuel production in our Escherichia coli test system. Because the transporters used in this study belong to the ubiquitous ATP-binding cassette protein family, we propose their use as "plug-and-play" biofuel-secreting systems in a variety of bacteria, cyanobacteria, diatoms, yeast, and algae used for biofuel production. This investigation showcases the potential of expressing desired membrane transport proteins in cell factories to achieve the export or import of substances of economic, environmental, or therapeutic importance.

  18. Systemic Foot-and-Mouth Disease Vaccination in Cattle Promotes Specific Antibody-Secreting Cells at the Respiratory Tract and Triggers Local Anamnestic Responses upon Aerosol Infection.

    Science.gov (United States)

    Pega, J; Di Giacomo, S; Bucafusco, D; Schammas, J M; Malacari, D; Barrionuevo, F; Capozzo, A V; Rodríguez, L L; Borca, M V; Pérez-Filgueira, M

    2015-09-01

    Foot-and-mouth disease (FMD) is a highly contagious viral disease affecting biungulate species. Commercial vaccines, formulated with inactivated FMD virus (FMDV), are regularly used worldwide to control the disease. Here, we studied the generation of antibody responses in local lymphoid tissues along the respiratory system in vaccinated and further aerosol-infected cattle. Animals immunized with a high-payload monovalent FMD vaccine developed high titers of neutralizing antibodies at 7 days postvaccination (dpv), reaching a plateau at 29 dpv. FMDV-specific antibody-secreting cells (ASC), predominantly IgM, were evident at 7 dpv in the prescapular lymph node (LN) draining the vaccination site and in distal LN draining the respiratory mucosa, although in lower numbers. At 29 dpv, a significant switch to IgG1 was clear in prescapular LN, while FMDV-specific ASC were detected in all lymphoid tissues draining the respiratory tract, mostly as IgM-secreting cells. None of the animals (n = 10) exhibited FMD symptoms after oronasal challenge at 30 dpv. Three days postinfection, a large increase in ASC numbers and rapid isotype switches to IgG1 were observed, particularly in LN-draining virus replication sites already described. These results indicate for the first time that systemic FMD vaccination in cattle effectively promotes the presence of anti-FMDV ASC in lymphoid tissues associated with the respiratory system. Oronasal infection triggered an immune reaction compatible with a local anamnestic response upon contact with the replicating FMDV, suggesting that FMD vaccination induces the circulation of virus-specific B lymphocytes, including memory B cells that differentiate into ASC soon after contact with the infective virus. Over recent decades, world animal health organizations as well as national sanitary authorities have supported the use of vaccination as an essential component of the official FMD control programs in both endemic and disease-free settings. Very few

  19. Evidence of the presence of a functional Dot/Icm type IV-B secretion system in the fish bacterial pathogen Piscirickettsia salmonis.

    Directory of Open Access Journals (Sweden)

    Fernando A Gómez

    Full Text Available Piscirickettsia salmonis is a fish bacterial pathogen that has severely challenged the sustainability of the Chilean salmon industry since its appearance in 1989. As this Gram-negative bacterium has been poorly characterized, relevant aspects of its life cycle, virulence and pathogenesis must be identified in order to properly design prophylactic procedures. This report provides evidence of the functional presence in P. salmonis of four genes homologous to those described for Dot/Icm Type IV Secretion Systems. The Dot/Icm System, the major virulence mechanism of phylogenetically related pathogens Legionella pneumophila and Coxiella burnetii, is responsible for their intracellular survival and multiplication, conditions that may also apply to P. salmonis. Our results demonstrate that the four P. salmonis dot/icm homologues (dotB, dotA, icmK and icmE are expressed both during in vitro tissue culture cells infection and growing in cell-free media, suggestive of their putative constitutive expression. Additionally, as it happens in other referential bacterial systems, temporal acidification of cell-free media results in over expression of all four P. salmonis genes, a well-known strategy by which SSTIV-containing bacteria inhibit phagosome-lysosome fusion to survive. These findings are very important to understand the virulence mechanisms of P. salmonis in order to design new prophylactic alternatives to control the disease.

  20. Mating systems, reproductive success, and sexual selection in secretive species: a case study of the western diamond-backed rattlesnake, Crotalus atrox.

    Science.gov (United States)

    Clark, Rulon W; Schuett, Gordon W; Repp, Roger A; Amarello, Melissa; Smith, Charles F; Herrmann, Hans-Werner

    2014-01-01

    Long-term studies of individual animals in nature contribute disproportionately to our understanding of the principles of ecology and evolution. Such field studies can benefit greatly from integrating the methods of molecular genetics with traditional approaches. Even though molecular genetic tools are particularly valuable for species that are difficult to observe directly, they have not been widely adopted. Here, we used molecular genetic techniques in a 10-year radio-telemetric investigation of the western diamond-backed rattlesnake (Crotalus atrox) for an analysis of its mating system and to measure sexual selection. Specifically, we used microsatellite markers to genotype 299 individuals, including neonates from litters of focal females to ascertain parentage using full-pedigree likelihood methods. We detected high levels of multiple paternity within litters, yet found little concordance between paternity and observations of courtship and mating behavior. Larger males did not father significantly more offspring, but we found evidence for size-specific male-mating strategies, with larger males guarding females for longer periods in the mating seasons. Moreover, the spatial proximity of males to mothers was significantly associated with reproductive success. Overall, our field observations alone would have been insufficient to quantitatively measure the mating system of this population of C. atrox, and we thus urge more widespread adoption of molecular tools by field researchers studying the mating systems and sexual selection of snakes and other secretive taxa.

  1. Analysis of secreted proteins from Aspergillus flavus.

    Science.gov (United States)

    Medina, Martha L; Haynes, Paul A; Breci, Linda; Francisco, Wilson A

    2005-08-01

    MS/MS techniques in proteomics make possible the identification of proteins from organisms with little or no genome sequence information available. Peptide sequences are obtained from tandem mass spectra by matching peptide mass and fragmentation information to protein sequence information from related organisms, including unannotated genome sequence data. This peptide identification data can then be grouped and reconstructed into protein data. In this study, we have used this approach to study protein secretion by Aspergillus flavus, a filamentous fungus for which very little genome sequence information is available. A. flavus is capable of degrading the flavonoid rutin (quercetin 3-O-glycoside), as the only source of carbon via an extracellular enzyme system. In this continuing study, a proteomic analysis was used to identify secreted proteins from A. flavus when grown on rutin. The growth media glucose and potato dextrose were used to identify differentially expressed secreted proteins. The secreted proteins were analyzed by 1- and 2-DE and MS/MS. A total of 51 unique A. flavus secreted proteins were identified from the three growth conditions. Ten proteins were unique to rutin-, five to glucose- and one to potato dextrose-grown A. flavus. Sixteen secreted proteins were common to all three media. Fourteen identifications were of hypothetical proteins or proteins of unknown functions. To our knowledge, this is the first extensive proteomic study conducted to identify the secreted proteins from a filamentous fungus.

  2. Effector protein translocation by the Coxiella burnetii Dot/Icm type IV secretion system requires endocytic maturation of the pathogen-occupied vacuole.

    Directory of Open Access Journals (Sweden)

    Hayley J Newton

    Full Text Available The human pathogen Coxiella burnetii encodes a type IV secretion system called Dot/Icm that is essential for intracellular replication. The Dot/Icm system delivers bacterial effector proteins into the host cytosol during infection. The effector proteins delivered by C. burnetii are predicted to have important functions during infection, but when these proteins are needed during infection has not been clearly defined. Here, we use a reporter system consisting of fusion proteins that have a β-lactamase enzyme (BlaM fused to C. burnetii effector proteins to study protein translocation by the Dot/Icm system. Translocation of BlaM fused to the effector proteins CBU0077, CBU1823 and CBU1524 was not detected until 8-hours after infection of HeLa cells, which are permissive for C. burnetii replication. Translocation of these effector fusion proteins by the Dot/Icm system required acidification of the Coxiella-containing vacuole. Silencing of the host genes encoding the membrane transport regulators Rab5 or Rab7 interfered with effector translocation, which indicates that effectors are not translocated until bacteria traffic to a late endocytic compartment in the host cell. Similar requirements for effector translocation were discerned in bone marrow macrophages derived from C57BL/6 mice, which are primary cells that restrict the intracellular replication of C. burnetii. In addition to requiring endocytic maturation of the vacuole for Dot/Icm-mediated translocation of effectors, bacterial transcription was required for this process. Thus, translocation of effector proteins by the C. burnetii Dot/Icm system occurs after acidification of the CCV and maturation of this specialized organelle to a late endocytic compartment. This indicates that creation of the specialized vacuole in which C. burnetii replicates represents a two-stage process mediated initially by host factors that regulate endocytic maturation and then by bacterial effectors delivered into

  3. Distinct evolution of TLR-mediated dendritic cell cytokine secretion in patients with limited and diffuse cutaneous systemic sclerosis.

    NARCIS (Netherlands)

    Bon, L. van; Popa, C.; Huibens, R.J.F.; Vonk, M.C.; York, M.; Simms, R.; Hesselstrand, R.; Wuttge, D.M.; Lafyatis, R.; Radstake, T.R.D.J.

    2010-01-01

    BACKGROUND: Systemic sclerosis (SSc) is an autoimmune disease and accumulating evidence suggests a role for Toll-like receptor (TLR)-mediated activation of dendritic cells (DCs). OBJECTIVE: To map TLR-mediated cytokine responses of DCs from patients with SSc. METHODS: 45 patients with SSc were

  4. Mycobacterial secretion systems ESX-1 and ESX-5 play distinct roles in host cell death and inflammasome activation

    KAUST Repository

    Abdallah, Abdallah; Bestebroer, Jovanka; Savage, Nigel D L; De Punder, Karin; Van Zon, Maaike; Wilson, Louis D.; Korbee, Cees J.; Van Der Sar, Astrid M.; Ottenhoff, Tom Hm M; Van Der Wel, Nicole N.; Bitter, Wilbert M.; Peters, Peter J.

    2011-01-01

    for the translocation of Mycobacterium tuberculosis or Mycobacterium marinum to the cytosol of host cells. However, the M. marinum ESX-5 mutant does not induce inflammasome activation and IL-1b activation. The ESX-5 system also induces a caspase-independent cell death

  5. Notch-deficient skin induces a lethal systemic B-lymphoproliferative disorder by secreting TSLP, a sentinel for epidermal integrity.

    Directory of Open Access Journals (Sweden)

    Shadmehr Demehri

    2008-05-01

    Full Text Available Epidermal keratinocytes form a highly organized stratified epithelium and sustain a competent barrier function together with dermal and hematopoietic cells. The Notch signaling pathway is a critical regulator of epidermal integrity. Here, we show that keratinocyte-specific deletion of total Notch signaling triggered a severe systemic B-lymphoproliferative disorder, causing death. RBP-j is the DNA binding partner of Notch, but both RBP-j-dependent and independent Notch signaling were necessary for proper epidermal differentiation and lipid deposition. Loss of both pathways caused a persistent defect in skin differentiation/barrier formation. In response, high levels of thymic stromal lymphopoietin (TSLP were released into systemic circulation by Notch-deficient keratinocytes that failed to differentiate, starting in utero. Exposure to high TSLP levels during neonatal hematopoiesis resulted in drastic expansion of peripheral pre- and immature B-lymphocytes, causing B-lymphoproliferative disorder associated with major organ infiltration and subsequent death, a previously unappreciated systemic effect of TSLP. These observations demonstrate that local skin perturbations can drive a lethal systemic disease and have important implications for a wide range of humoral and autoimmune diseases with skin manifestations.

  6. Discovery of plant phenolic compounds that act as type III secretion system inhibitors or inducers of the fire blight pathogen, Erwinia amylovora.

    Science.gov (United States)

    Khokhani, Devanshi; Zhang, Chengfang; Li, Yan; Wang, Qi; Zeng, Quan; Yamazaki, Akihiro; Hutchins, William; Zhou, Shan-Shan; Chen, Xin; Yang, Ching-Hong

    2013-09-01

    Erwinia amylovora causes a devastating disease called fire blight in rosaceous plants. The type III secretion system (T3SS) is one of the important virulence factors utilized by E. amylovora in order to successfully infect its hosts. By using a green fluorescent protein (GFP) reporter construct combined with a high-throughput flow cytometry assay, a library of phenolic compounds and their derivatives was studied for their ability to alter the expression of the T3SS. Based on the effectiveness of the compounds on the expression of the T3SS pilus, the T3SS inhibitors 4-methoxy-cinnamic acid (TMCA) and benzoic acid (BA) and one T3SS inducer, trans-2-(4-hydroxyphenyl)-ethenylsulfonate (EHPES), were chosen for further study. Both the T3SS inhibitors (TMCA and BA) and the T3SS inducer (EHPES) were found to alter the expression of T3SS through the HrpS-HrpL pathway. Additionally, TMCA altered T3SS expression through the rsmBEa-RsmAEa system. Finally, we found that TMCA and BA weakened the hypersensitive response (HR) in tobacco by suppressing the T3SS of E. amylovora. In our study, we identified phenolic compounds that specifically targeted the T3SS. The T3SS inhibitor may offer an alternative approach to antimicrobial therapy by targeting virulence factors of bacterial pathogens.

  7. Purification and characterization of a chemoattractant from electric shock-induced earthworm secretion, its receptor binding, and signal transduction through the vomeronasal system of garter snakes.

    Science.gov (United States)

    Jiang, X C; Inouchi, J; Wang, D; Halpern, M

    1990-05-25

    Following shocks with low voltage electric current, earthworms, Lumbricus terrestris, secrete a yellow mucus that has alarm properties for conspecifics and chemoattractive properties for garter snakes, Thamnophis sirtalis. A proteinaceous chemoattractant for garter snakes has been isolated and purified to homogeneity from such secretions by means of permeation chromatography and semipreparative nondenaturing polyacrylamide gel electrophoresis. The purified protein is highly attractive to garter snakes; it loses its activity after proteolytic digestion. It is a glycoprotein consisting of a single polypeptide chain with an NH2-terminal alanine. This chemoattractant has a minimum molecular mass of 15.4 kDa calculated from its amino acid and carbohydrate contents and an apparent molecular mass of about 20 kDa as estimated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It has a pI of about 4.0, and it binds wheat germ agglutinin but not concanavalin A. This chemoattractant shows a protein to carbohydrate ratio of 2.0 +/- 0.08 (n = 5) and a ratio of total sugar to amino sugar of 1.9 +/- 0.08 (n = 3). The sequence of its NH2-terminal 15 amino acid residues has been determined. Studies were also conducted on the chemosignal transduction through the vomeronasal sensory system of the garter snake. Dot blot analysis showed that the purified chemoattractant bound to snake vomeronasal sensory epithelial membrane fractions. It did not bind to membrane extracts of the nonsensory epithelium of the vomeronasal mushroom body. The chemoattractant also bound specifically to vomeronasal sensory epithelial membrane in a reversible and saturable fashion with Kd and Bmax values of about 0.3 microM and 0.4 nmol/mg of protein, respectively. In electrophysiological studies, the chemoattractant applied to the vomeronasal epithelium caused an increase in firing rate of individual neurons in the accessory olfactory bulb of garter snakes, the projection site for vomeronasal

  8. Expression, purification, crystallization and preliminary crystallographic analysis of BipD, a component of the Burkholderia pseudomallei type III secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Roversi, Pietro; Johnson, Steven [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU (United Kingdom); Field, Terry [Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire RG20 7NN (United Kingdom); Deane, Janet E. [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU (United Kingdom); Galyov, Edouard E. [Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire RG20 7NN (United Kingdom); Lea, Susan M., E-mail: susan.lea@biop.ox.ac.uk [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU (United Kingdom); Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE (United Kingdom)

    2006-09-01

    A construct consisting of residues 10–310 of mature BipD, a component of the B. pseudomallei type III secretion system, has been crystallized. Native BipD crystals and SeMet and K{sub 2}PtCl{sub 4} derivative crystals have undergone preliminary crystallographic analysis. A construct consisting of residues 10–310 of BipD, a component of the Burkholderia pseudomallei type III secretion system (T3SS), has been overexpressed as a GST fusion, cleaved from the GST tag and purified. Crystals were grown of native and selenomethionine-labelled BipD. The crystals grow in two different polymorphs from the same condition. The first polymorph belongs to space group C222, with unit-cell parameters a = 103.98, b = 122.79, c = 49.17 Å, a calculated Matthews coefficient of 2.4 Å{sup 3} Da{sup −1} (47% solvent content) and one molecule per asymmetric unit. The second polymorph belongs to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 136.47, b = 89.84, c = 50.15 Å, and a calculated Matthews coefficient of 2.3 Å{sup 3} Da{sup −1} (45% solvent content) for two molecules per asymmetric unit (analysis of the self-rotation function indicates the presence of a weak twofold non-crystallographic symmetry axis in this P2{sub 1}2{sub 1}2 form). The native crystals of both forms give diffraction data to 2.7 Å resolution, while the SeMet-labelled P2{sub 1}2{sub 1}2 crystals diffract to 3.3 Å resolution. A K{sub 2}PtCl{sub 4} derivative of the P2{sub 1}2{sub 1}2 form was also obtained and data were collected to 2.7 Å with radiation of wavelength λ = 0.933 Å. The Pt-derivative anomalous difference Patterson map revealed two self-peaks on the Harker sections.

  9. Applying secret sharing for HIS backup exchange.

    Science.gov (United States)

    Kuroda, Tomohiro; Kimura, Eizen; Matsumura, Yasushi; Yamashita, Yoshinori; Hiramatsu, Haruhiko; Kume, Naoto; Sato, Atsushi

    2013-01-01

    To secure business continuity is indispensable for hospitals to fulfill its social responsibility under disasters. Although to back up the data of the hospital information system (HIS) at multiple remote sites is a key strategy of business continuity plan (BCP), the requirements to treat privacy sensitive data jack up the cost for the backup. The secret sharing is a method to split an original secret message up so that each individual piece is meaningless, but putting sufficient number of pieces together to reveal the original message. The secret sharing method eases us to exchange HIS backups between multiple hospitals. This paper evaluated the feasibility of the commercial secret sharing solution for HIS backup through several simulations. The result shows that the commercial solution is feasible to realize reasonable HIS backup exchange platform when template of contract between participating hospitals is ready.

  10. Centriole polarisation to the immunological synapse directs secretion from cytolytic cells of both the innate and adaptive immune systems

    Directory of Open Access Journals (Sweden)

    Arico Maurizo

    2011-06-01

    Full Text Available Abstract Background Cytolytic cells of the immune system destroy pathogen-infected cells by polarised exocytosis of secretory lysosomes containing the pore-forming protein perforin. Precise delivery of this lethal hit is essential to ensuring that only the target cell is destroyed. In cytotoxic T lymphocytes (CTLs, this is accomplished by an unusual movement of the centrosome to contact the plasma membrane at the centre of the immunological synapse formed between killer and target cells. Secretory lysosomes are directed towards the centrosome along microtubules and delivered precisely to the point of target cell recognition within the immunological synapse, identified by the centrosome. We asked whether this mechanism of directing secretory lysosome release is unique to CTL or whether natural killer (NK and invariant NKT (iNKT cytolytic cells of the innate immune system use a similar mechanism to focus perforin-bearing lysosome release. Results NK cells were conjugated with B-cell targets lacking major histocompatibility complex class I 721.221 cells, and iNKT cells were conjugated with glycolipid-pulsed CD1-bearing targets, then prepared for thin-section electron microscopy. High-resolution electron micrographs of the immunological synapse formed between NK and iNKT cytolytic cells with their targets revealed that in both NK and iNKT cells, the centrioles could be found associated (or 'docked' with the plasma membrane within the immunological synapse. Secretory clefts were visible within the synapses formed by both NK and iNKT cells, and secretory lysosomes were polarised along microtubules leading towards the docked centrosome. The Golgi apparatus and recycling endosomes were also polarised towards the centrosome at the plasma membrane within the synapse. Conclusions These results reveal that, like CTLs of the adaptive immune system, the centrosomes of NK and iNKT cells (cytolytic cells of the innate immune system direct secretory lysosomes to

  11. Centriole polarisation to the immunological synapse directs secretion from cytolytic cells of both the innate and adaptive immune systems.

    Science.gov (United States)

    Stinchcombe, Jane C; Salio, Mariolina; Cerundolo, Vincenzo; Pende, Daniela; Arico, Maurizo; Griffiths, Gillian M

    2011-06-28

    Cytolytic cells of the immune system destroy pathogen-infected cells by polarised exocytosis of secretory lysosomes containing the pore-forming protein perforin. Precise delivery of this lethal hit is essential to ensuring that only the target cell is destroyed. In cytotoxic T lymphocytes (CTLs), this is accomplished by an unusual movement of the centrosome to contact the plasma membrane at the centre of the immunological synapse formed between killer and target cells. Secretory lysosomes are directed towards the centrosome along microtubules and delivered precisely to the point of target cell recognition within the immunological synapse, identified by the centrosome. We asked whether this mechanism of directing secretory lysosome release is unique to CTL or whether natural killer (NK) and invariant NKT (iNKT) cytolytic cells of the innate immune system use a similar mechanism to focus perforin-bearing lysosome release. NK cells were conjugated with B-cell targets lacking major histocompatibility complex class I 721.221 cells, and iNKT cells were conjugated with glycolipid-pulsed CD1-bearing targets, then prepared for thin-section electron microscopy. High-resolution electron micrographs of the immunological synapse formed between NK and iNKT cytolytic cells with their targets revealed that in both NK and iNKT cells, the centrioles could be found associated (or 'docked') with the plasma membrane within the immunological synapse. Secretory clefts were visible within the synapses formed by both NK and iNKT cells, and secretory lysosomes were polarised along microtubules leading towards the docked centrosome. The Golgi apparatus and recycling endosomes were also polarised towards the centrosome at the plasma membrane within the synapse. These results reveal that, like CTLs of the adaptive immune system, the centrosomes of NK and iNKT cells (cytolytic cells of the innate immune system) direct secretory lysosomes to the immunological synapse. Morphologically, the

  12. Central nervous system neuropeptide Y regulates mediators of hepatic phospholipid remodeling and very low-density lipoprotein triglyceride secretion via sympathetic innervation

    Directory of Open Access Journals (Sweden)

    Jennifer M. Rojas

    2015-03-01

    Conclusions: These data support a model in which CNS NPY modulates mediators of hepatic PL remodeling and VLDL maturation to stimulate VLDL-TG secretion that is dependent on the Y1 receptor and sympathetic signaling to the liver.

  13. High level heterologous protein production in Lactococcus and Lactobacillus using a new secretion system based on the Lactobacillus brevis S-layer signals.

    Science.gov (United States)

    Savijoki, K; Kahala, M; Palva, A

    1997-02-28

    A secretion cassette, based on the expression and secretion signals of a S-layer protein (SlpA) from Lactobacillus brevis, was constructed. E. coli beta-lactamase (Bla) was used as the reporter protein to determine the functionality of the S-layer signals for heterologous expression and secretion in Lactococcus lactis, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus gasseri and Lactobacillus casei using a low-copy-number plasmid derived from pGK12. In all hosts tested, the bla gene was expressed under the slpA signals and all Bla activity was secreted to the culture medium. The Lb. brevis S-layer promoters were very efficiently recognized in L. lactis, Lb. brevis and Lb. plantarum, whereas in Lb. gasseri the slpA promoter region appeared to be recognized at a lower level and in Lb. casei the level of transcripts was below the detection limit. The production of Bla was mainly restricted to the exponential phase of growth. The highest yield of Bla was obtained with L. lactis and Lb. brevis. Without pH control, substantial degradation of Bla occurred during prolonged cultivations with all lactic acid bacteria (LAB) tested. When growing L. lactis and Lb. brevis under pH control, the Bla activity could be stabilized also at the stationary phase. L. lactis produced up to 80 mg/l of Bla which to our knowledge represents the highest amount of a heterologous protein secreted by LAB so far. The short production phase implied a very high rate of secretion with a calculated value of 5 x 10(5) Bla molecules/cell per h. Such a high rate was also observed with Lb. plantarum, whereas in Lb. brevis the competition between the wild type slpA gene and the secretion construct probably lowered the rate of Bla production. The results obtained indicate wide applicability of the Lb. brevis slpA signals for efficient protein production and secretion in LAB.

  14. Reproductive biology and nectar secretion dynamics of Penstemon gentianoides (Plantaginaceae: a perennial herb with a mixed pollination system?

    Directory of Open Access Journals (Sweden)

    Lucía Salas-Arcos

    2017-08-01

    Full Text Available Background In many plant species, pollination syndromes predict the most effective pollinator. However, other floral visitors may also offer effective pollination services and promote mixed pollination systems. Several species of the species-rich Penstemon (Plantaginaceae exhibit a suite of floral traits that suggest adaptation for pollination by both hymenopterans and hummingbirds. Transitions from the ancestral hymenopteran pollination syndrome to more derived hummingbird pollination syndrome may be promoted if the quantity or quality of visits by hummingbirds is increased and if the ancestral pollinator group performs less efficiently. The quantification of such shifts in pollination systems in the group is still limited. We aimed to investigate floral traits linked to this pollination syndrome in Penstemon gentianoides with flowers visited by bumblebees and hummingbirds. Methods We investigated the floral biology, pollinator assemblages, breeding system and nectar production patterns ofP. gentianoides inhabiting a temperate montane forest in central Mexico. Pollination experiments were also conducted to assess the pollinator effectiveness of bumblebees and hummingbirds. Results P. gentianoides flowers are protandrous, with 8-d male phase (staminate flowers, followed by the ∼1–7 d female phase (pistillate phase. Flowers display traits associated with hymenopteran pollination, including purple flowers abruptly ampliate-ventricose to a broad throat with anthers and stigmas included, and long lifespans. However, the nectar available in the morning hours was abundant and dilute, traits linked to flowers with a hummingbird pollination syndrome. Two hummingbird species made most of the visits to flowers, Selasphorus platycercus (30.3% of all visits, followed by Archilochus colubris (11.3%. Bumblebees (Bombus ephippiatus, B. huntii and B. weisi accounted for 51.8% of all recorded visits, but their foraging activity was restricted to the warmer

  15. Epithelial cells detect functional type III secretion system of enteropathogenic Escherichia coli through a novel NF-κB signaling pathway.

    Directory of Open Access Journals (Sweden)

    Yael Litvak

    2017-07-01

    Full Text Available Enteropathogenic Escherichia coli (EPEC, a common cause of infant diarrhea, is associated with high risk of mortality in developing countries. The primary niche of infecting EPEC is the apical surface of intestinal epithelial cells. EPEC employs a type three secretion system (TTSS to inject the host cells with dozens of effector proteins, which facilitate attachment to these cells and successful colonization. Here we show that EPEC elicit strong NF-κB activation in infected host cells. Furthermore, the data indicate that active, pore-forming TTSS per se is necessary and sufficient for this NF-κB activation, regardless of any specific effector or protein translocation. Importantly, upon infection with wild type EPEC this NF-κB activation is antagonized by anti-NF-κB effectors, including NleB, NleC and NleE. Accordingly, this NF-κB activation is evident only in cells infected with EPEC mutants deleted of nleB, nleC, and nleE. The TTSS-dependent NF-κB activation involves a unique pathway, which is independent of TLRs and Nod1/2 and converges with other pathways at the level of TAK1 activation. Taken together, our results imply that epithelial cells have the capacity to sense the EPEC TTSS and activate NF-κB in response. Notably, EPEC antagonizes this capacity by delivering anti-NF-κB effectors into the infected cells.

  16. The genomes of closely related Pantoea ananatis maize seed endophytes having different effects on the host plant differ in secretion system genes and mobile genetic elements

    Directory of Open Access Journals (Sweden)

    Raheleh eSheibani-Tezerji

    2015-05-01

    Full Text Available The seed as a habitat for microorganisms is as yet under-explored and has quite distinct characteristics as compared to other vegetative plant tissues. In this study, we investigated three closely related P. ananatis strains (named S6, S7 and S8, which were isolated from maize seeds of healthy plants. Plant inoculation experiments revealed that each of these strains exhibited a different phenotype ranging from weak pathogenic (S7, commensal (S8, to a beneficial, growth-promoting effect (S6 in maize. We performed a comparative genomics analysis in order to find genetic determinants responsible for the differences observed. Recent studies provided exciting insight into the genetic drivers of niche adaption and functional diversification of the genus Pantoea. However, we report here for the first time on the analysis of P. ananatis strains colonizing the same ecological niche but showing distinct interaction strategies with the host plant. Our comparative analysis revealed that genomes of these three strains are highly similar. However, genomic differences in genes encoding protein secretion systems and putative effectors, and transposase/integrases/phage related genes could be observed.

  17. Salivary Gland Secretion.

    Science.gov (United States)

    Dorman, H. L.; And Others

    1981-01-01

    Describes materials and procedures for an experiment utilizing a live dog to demonstrate: (1) physiology of the salivary gland; (2) parasympathetic control of the salivary gland; (3) influence of varying salivary flow rates on sodium and potassium ions, osmolarity and pH; and (4) salivary secretion as an active process. (DS)

  18. 'Secret' Shuttle payloads revealed

    Science.gov (United States)

    Powell, Joel W.

    1993-05-01

    A secret military payload carried by the orbiter Discovery launched on January 24 1985 is discussed. Secondary payloads on the military Shuttle flights are briefly reviewed. Most of the military middeck experiments were sponsored by the Space Test Program established at the Pentagon to oversee all Defense Department space research projects.

  19. Inappropriate Antidiuretic Hormone Secretion

    African Journals Online (AJOL)

    1974-06-08

    Jun 8, 1974 ... with Addison's disease, diarrhoea or salt-losing nephritis. (asymptomatic hyponatraemia).~ Schwartz et al.3 stud;ed two patients with anaplastic bronchus carcinoma and hyponatraemia in 1957, and they suggested that there was an inappropriate secretion of antidiuretic hormone (ADH). It is now well ...

  20. Physiology of bile secretion.

    Science.gov (United States)

    Esteller, Alejandro

    2008-10-07

    The formation of bile depends on the structural and functional integrity of the bile-secretory apparatus and its impairment, in different situations, results in the syndrome of cholestasis. The structural bases that permit bile secretion as well as various aspects related with its composition and flow rate in physiological conditions will first be reviewed. Canalicular bile is produced by polarized hepatocytes that hold transporters in their basolateral (sinusoidal) and apical (canalicular) plasma membrane. This review summarizes recent data on the molecular determinants of this primary bile formation. The major function of the biliary tree is modification of canalicular bile by secretory and reabsorptive processes in bile-duct epithelial cells (cholangiocytes) as bile passes through bile ducts. The mechanisms of fluid and solute transport in cholangiocytes will also be discussed. In contrast to hepatocytes where secretion is constant and poorly controlled, cholangiocyte secretion is regulated by hormones and nerves. A short section dedicated to these regulatory mechanisms of bile secretion has been included. The aim of this revision was to set the bases for other reviews in this series that will be devoted to specific issues related with biliary physiology and pathology.

  1. A Public Secret

    DEFF Research Database (Denmark)

    Bregnbæk, Susanne

    2011-01-01

    This article is based on anthropological fieldwork undertaken at two elite universities in Beijing. It addresses the paradoxical situation of the many instances of suicide among Chinese elite university students in Beijing, which constitute a public secret. The pressure of education weighs heavily...

  2. MONA Implementation Secrets

    DEFF Research Database (Denmark)

    Klarlund, Nils; Møller, Anders; Schwartzbach, Michael Ignatieff

    2002-01-01

    a period of six years. Compared to the first naive version, the present tool is faster by several orders of magnitude. This speedup is obtained from many different contributions working on all levels of the compilation and execution of formulas. We present a selection of implementation "secrets" that have...

  3. The role of jasmonates in floral nectar secretion.

    Directory of Open Access Journals (Sweden)

    Venkatesan Radhika

    Full Text Available Plants produce nectar in their flowers as a reward for their pollinators and most of our crops depend on insect pollination, but little is known on the physiological control of nectar secretion. Jasmonates are well-known for their effects on senescence, the development and opening of flowers and on plant defences such as extrafloral nectar. Their role in floral nectar secretion has, however, not been explored so far. We investigated whether jasmonates have an influence on floral nectar secretion in oil-seed rape, Brassica napus. The floral tissues of this plant produced jasmonic acid (JA endogenously, and JA concentrations peaked shortly before nectar secretion was highest. Exogenous application of JA to flowers induced nectar secretion, which was suppressed by treatment with phenidone, an inhibitor of JA synthesis. This effect could be reversed by additional application of JA. Jasmonoyl-isoleucine and its structural mimic coronalon also increased nectar secretion. Herbivory or addition of JA to the leaves did not have an effect on floral nectar secretion, demonstrating a functional separation of systemic defence signalling from reproductive nectar secretion. Jasmonates, which have been intensively studied in the context of herbivore defences and flower development, have a profound effect on floral nectar secretion and, thus, pollination efficiency in B. napus. Our results link floral nectar secretion to jasmonate signalling and thereby integrate the floral nectar secretion into the complex network of oxylipid-mediated developmental processes of plants.

  4. An N-terminal Retention Module Anchors the Giant Adhesin LapA of Pseudomonas fluorescens at the Cell Surface: A Novel Sub-family of Type I Secretion Systems.

    Science.gov (United States)

    Smith, T Jarrod; Font, Maria E; Kelly, Carolyn M; Sondermann, Holger; O'Toole, George A

    2018-02-05

    LapA of Pseudomonas fluorescens Pf0-1 belongs to a diverse family of cell surface associated bacterial adhesins that are secreted via the type-1 secretion system (T1SS). We previously reported that the periplasmic protease LapG cleaves the N-terminus of LapA at a canonical dialanine motif to release the adhesin from the cell surface under conditions unfavorable to biofilm formation, thus decreasing biofilm formation. Here, we characterize LapA as the first type 1 secreted substrate that does not follow the "one-step" rule of T1SS. Rather, a novel N-terminal element, called the retention module (RM), localizes LapA at the cell surface as a secretion intermediate. Our genetic, biochemical, and molecular modeling analysis support a model wherein LapA is tethered to the cell surface through its T1SS outer membrane TolC-like pore, LapE, until LapG cleaves LapA in the periplasm. We further demonstrate this unusual retention strategy is likely conserved among LapA-like proteins, and reveals a new subclass of T1SS ABC transporters involved in transporting this group of surface-associated, LapA-like adhesins. These studies demonstrate a novel cell surface retention strategy used throughout the Proteobacteria and highlight a previously unappreciated flexibility of function for T1SS. Importance. Bacteria have evolved multiple secretion strategies to interact with their environment. For many bacteria, the secretion of cell surface associated adhesins is key for initiating contact with a preferred substratum to facilitate biofilm formation. Our work demonstrates that P. fluorescens uses a previously unrecognized secretion strategy to retain the giant adhesin LapA at its cell surface. Further, we identify likely LapA-like adhesins in various pathogenic and commensal Proteobacteria and provide phylogenetic evidence that these adhesins are secreted by a new subclass of T1SS ABC transporters. Copyright © 2018 American Society for Microbiology.

  5. Peptides and neurotransmitters that affect renin secretion

    Science.gov (United States)

    Ganong, W. F.; Porter, J. P.; Bahnson, T. D.; Said, S. I.

    1984-01-01

    Substance P inhibits renin secretion. This polypeptide is a transmitter in primary afferent neurons and is released from the peripheral as well as the central portions of these neurons. It is present in afferent nerves from the kidneys. Neuropeptide Y, which is a cotransmitter with norepinephrine and epinephrine, is found in sympathetic neurons that are closely associated with and presumably innervate the juxtagolmerular cells. Its effect on renin secretion is unknown, but it produces renal vasoconstriction and natriuresis. Vasoactive intestinal polypeptide (VIP) is a cotransmitter with acetylocholine in cholinergic neurons, and this polypeptide stimulates renin secretion. We cannot find any evidence for its occurence in neurons in the kidneys, but various stimuli increase plasma VIP to levels comparable to those produced by doses of exogenous VIP which stimulated renin secretion. Neostigmine increases plasma VIP and plasma renin activity, and the VIP appears to be responsible for the increase in renin secretion, since the increase is not blocked by renal denervation or propranolol. Stimulation of various areas in the brain produces sympathetically mediated increases in plasma renin activity associated with increases in blood pressure. However, there is pharmacological evidence that the renin response can be separated from the blood pressure response. In anaesthetized dogs, drugs that increase central serotonergic discharge increase renin secretion without increasing blood pressure. In rats, activation of sertonergic neurons in the dorsal raphe nucleus increases renin secretion by a pathway that projects from this nucleus to the ventral hypothalamus, and from there to the kidneys via the sympathetic nervous system. The serotonin releasing drug parachloramphetamine also increases plasma VIP, but VIP does not appear to be the primary mediator of the renin response. There is preliminary evidence that the serotonergic neurons in the dorsal raphe nucleus are part of the

  6. Wrapped up in Covers: Preschoolers' Secrets and Secret Hiding Places

    Science.gov (United States)

    Corson, Kimberly; Colwell, Malinda J.; Bell, Nancy J.; Trejos-Castillo, Elizabeth

    2014-01-01

    In this qualitative study, interviews about children's secret hiding places were conducted with 3-5-year-olds (n?=?17) in a university sponsored preschool programme using art narratives. Since prior studies indicate that children understand the concept of a secret as early as five and that they associate secrets with hiding places, the purpose of…

  7. Metformin Ameliorates Dysfunctional Traits of Glibenclamide- and Glucose-Induced Insulin Secretion by Suppression of Imposed Overactivity of the Islet Nitric Oxide Synthase-NO System.

    Directory of Open Access Journals (Sweden)

    Ingmar Lundquist

    Full Text Available Metformin lowers diabetic blood glucose primarily by reducing hepatic gluconeogenesis and increasing peripheral glucose uptake. However, possible effects by metformin on beta-cell function are incompletely understood. We speculated that metformin might positively influence insulin secretion through impacting the beta-cell nitric oxide synthase (NOS-NO system, a negative modulator of glucose-stimulated insulin release. In short-time incubations with isolated murine islets either glibenclamide or high glucose augmented insulin release associated with increased NO production from both neural and inducible NOS. Metformin addition suppressed the augmented NO generation coinciding with amplified insulin release. Islet culturing with glibenclamide or high glucose revealed pronounced fluorescence of inducible NOS in the beta-cells being abolished by metformin co-culturing. These findings were reflected in medium nitrite-nitrate levels. A glucose challenge following islet culturing with glibenclamide or high glucose revealed markedly impaired insulin response. Metformin co-culturing restored this response. Culturing murine islets and human islets from controls and type 2 diabetics with high glucose or high glucose + glibenclamide induced a pronounced decrease of cell viability being remarkably restored by metformin co-culturing. We show here, that imposed overactivity of the beta-cell NOS-NO system by glibenclamide or high glucose leads to insulin secretory dysfunction and reduced cell viability and also, importantly, that these effects are relieved by metformin inhibiting beta-cell NO overproduction from both neural and inducible NOS thus ameliorating a concealed negative influence by NO induced by sulfonylurea treatment and/or high glucose levels. This double-edged effect of glibenclamide on the beta-cellsuggests sulfonylurea monotherapy in type 2 diabetes being avoided.

  8. Prolonged Expression of Secreted Enzymes in Dogs After Liver-Directed Delivery of Sleeping Beauty Transposons: Implications for Non-Viral Gene Therapy of Systemic Disease.

    Science.gov (United States)

    Aronovich, Elena L; Hyland, Kendra A; Hall, Bryan C; Bell, Jason B; Olson, Erik R; Rusten, Myra Urness; Hunter, David W; Ellinwood, N Matthew; McIvor, R Scott; Hackett, Perry B

    2017-07-01

    The non-viral, integrating Sleeping Beauty (SB) transposon system is efficient in treating systemic monogenic disease in mice, including hemophilia A and B caused by deficiency of blood clotting factors and mucopolysaccharidosis types I and VII caused by α-L-iduronidase (IDUA) and β-glucuronidase (GUSB) deficiency, respectively. Modified approaches of the hydrodynamics-based procedure to deliver transposons to the liver in dogs were recently reported. Using the transgenic canine reporter secreted alkaline phosphatase (cSEAP), transgenic protein in the plasma was demonstrated for up to 6 weeks post infusion. This study reports that immunosuppression of dogs with gadolinium chloride (GdCl 3 ) prolonged the presence of cSEAP in the circulation up to 5.5 months after a single vector infusion. Transgene expression declined gradually but appeared to stabilize after about 2 months at approximately fourfold baseline level. Durability of transgenic protein expression in the plasma was inversely associated with transient increase of liver enzymes alanine transaminase and aspartate transaminase in response to the plasmid delivery procedure, which suggests a deleterious effect of hepatocellular toxicity on transgene expression. GdCl 3 treatment was ineffective for repeat vector infusions. In parallel studies, dogs were infused with potentially therapeutic transposons. Activities of transgenic IDUA and GUSB in plasma peaked at 50-350% of wildtype, but in the absence of immunosuppression lasted only a few days. Transposition was detectable by excision assay only when the most efficient transposase, SB100X, was used. Dogs infused with transposons encoding canine clotting factor IX (cFIX) were treated with GdCl 3 and showed expression profiles similar to those in cSEAP-infused dogs, with expression peaking at 40% wt (2 μg/mL). It is concluded that GdCl 3 can support extended transgene expression after hydrodynamic introduction of SB transposons in dogs, but that alternative

  9. Extracellular secretion of recombinant proteins

    Science.gov (United States)

    Linger, Jeffrey G.; Darzins, Aldis

    2014-07-22

    Nucleic acids encoding secretion signals, expression vectors containing the nucleic acids, and host cells containing the expression vectors are disclosed. Also disclosed are polypeptides that contain the secretion signals and methods of producing polypeptides, including methods of directing the extracellular secretion of the polypeptides. Exemplary embodiments include cellulase proteins fused to secretion signals, methods to produce and isolate these polypeptides, and methods to degrade lignocellulosic biomass.

  10. Pathophysiology of glucagon secretion

    International Nuclear Information System (INIS)

    Boettger, J.; Pabst, H.W.

    1980-01-01

    Pathophysiology of glucagon secretion is reviewed in brief separating hyperglucagonemic from hypoclucagonemic states. Many questions concerning the role of glucagon in diabetes mellitus and in other diseases are still unresolved. The clucagon RIA is of clinical significance in a few diseases like glucagonoma, which may present without symptoms of the 'glucagonoma syndrome', the probably very rare hyperglucagonemia and some of the spontaneous hypoglycemias. Glucagon secretion may be evaluated by the determination of fasting immunoreactive glucagon (IRG) and by appropriate function tests as stimulation with i.v. arginine and suppression with oral glucose. However, the glucagon RIA at present is not a routine method, although commercial kits are available. Many pitfalls of radioimmunological glucagon determination still exist. (orig.) [de

  11. Bucarest, Strictement Secret

    Directory of Open Access Journals (Sweden)

    Ionela Mihai

    2010-07-01

    Full Text Available L’émission Bucarest, strictement secret représente un documentaire organisésous la forme d’une série télé, qui dépeint le Bucarest à partir de deux perspectives: de l’histoire, de la conte et du lieu. La valeur d’une cité réside dans l’existence d’une mystique, d’un romantisme abscons, à part et des caractères empruntés de drames de Shakespeare, mystérieux, serrés d’angoisse et des secrets qui assombrissent leur existence. Par conséquence, le rôle du metteur en scène est de dévoiler leur vraie identité et de remettre en place, autant que possible, la vérité.

  12. Type VI secretion systems of human gut Bacteroidales segregate into three genetic architectures, two of which are contained on mobile genetic elements.

    Science.gov (United States)

    Coyne, Michael J; Roelofs, Kevin G; Comstock, Laurie E

    2016-01-15

    Type VI secretion systems (T6SSs) are contact-dependent antagonistic systems employed by Gram negative bacteria to intoxicate other bacteria or eukaryotic cells. T6SSs were recently discovered in a few Bacteroidetes strains, thereby extending the presence of these systems beyond Proteobacteria. The present study was designed to analyze in a global nature the diversity, abundance, and properties of T6SSs in the Bacteroidales, the most predominant Gram negative bacterial order of the human gut. By performing extensive bioinformatics analyses and creating hidden Markov models for Bacteroidales Tss proteins, we identified 130 T6SS loci in 205 human gut Bacteroidales genomes. Of the 13 core T6SS proteins of Proteobacteria, human gut Bacteroidales T6SS loci encode orthologs of nine, and an additional five other core proteins not present in Proteobacterial T6SSs. The Bacteroidales T6SS loci segregate into three distinct genetic architectures with extensive DNA identity between loci of a given genetic architecture. We found that divergent DNA regions of a genetic architecture encode numerous types of effector and immunity proteins and likely include new classes of these proteins. TheT6SS loci of genetic architecture 1 are contained on highly similar integrative conjugative elements (ICEs), as are the T6SS loci of genetic architecture 2, whereas the T6SS loci of genetic architecture 3 are not and are confined to Bacteroides fragilis. Using collections of co-resident Bacteroidales strains from human subjects, we provide evidence for the transfer of genetic architecture 1 T6SS loci among co-resident Bacteroidales species in the human gut. However, we also found that established ecosystems can harbor strains with distinct T6SS of all genetic architectures. This is the first study to comprehensively analyze of the presence and diversity of T6SS loci within an order of bacteria and to analyze T6SSs of bacteria from a natural community. These studies demonstrate that more than

  13. The cytotoxic type 3 secretion system 1 of Vibrio rewires host gene expression to subvert cell death and activate cell survival pathways.

    Science.gov (United States)

    De Nisco, Nicole J; Kanchwala, Mohammed; Li, Peng; Fernandez, Jessie; Xing, Chao; Orth, Kim

    2017-05-16

    Bacterial effectors potently manipulate host signaling pathways. The marine bacterium Vibrio parahaemolyticus ( V. para ) delivers effectors into host cells through two type 3 secretion systems (T3SSs). T3SS1 is vital for V. para survival in the environment, whereas T3SS2 causes acute gastroenteritis in human hosts. Although the natural host is undefined, T3SS1 effectors attack highly conserved cellular processes and pathways to orchestrate nonapoptotic cell death. To understand how the concerted action of T3SS1 effectors globally affects host cell signaling, we compared gene expression changes over time in primary fibroblasts infected with V. para that have a functional T3SS1 (T3SS1 + ) to those in cells infected with V. para lacking T3SS1 (T3SS1 - ). Overall, the host transcriptional response to both T3SS1 + and T3SS1 - V. para was rapid, robust, and temporally dynamic. T3SS1 rewired host gene expression by specifically altering the expression of 398 genes. Although T3SS1 effectors targeted host cells at the posttranslational level to cause cytotoxicity, V. para T3SS1 also precipitated a host transcriptional response that initially activated cell survival and repressed cell death networks. The increased expression of several key prosurvival transcripts mediated by T3SS1 depended on a host signaling pathway that is silenced posttranslationally later in infection. Together, our analysis reveals a complex interplay between the roles of T3SS1 as both a transcriptional and posttranslational manipulator of host cell signaling. Copyright © 2017, American Association for the Advancement of Science.

  14. Whole genome sequencing and analysis of Campylobacter coli YH502 from retail chicken reveals a plasmid-borne type VI secretion system

    Directory of Open Access Journals (Sweden)

    Sandeep Ghatak

    2017-03-01

    Full Text Available Campylobacter is a major cause of foodborne illnesses worldwide. Campylobacter infections, commonly caused by ingestion of undercooked poultry and meat products, can lead to gastroenteritis and chronic reactive arthritis in humans. Whole genome sequencing (WGS is a powerful technology that provides comprehensive genetic information about bacteria and is increasingly being applied to study foodborne pathogens: e.g., evolution, epidemiology/outbreak investigation, and detection. Herein we report the complete genome sequence of Campylobacter coli strain YH502 isolated from retail chicken in the United States. WGS, de novo assembly, and annotation of the genome revealed a chromosome of 1,718,974 bp and a mega-plasmid (pCOS502 of 125,964 bp. GC content of the genome was 31.2% with 1931 coding sequences and 53 non-coding RNAs. Multiple virulence factors including a plasmid-borne type VI secretion system and antimicrobial resistance genes (beta-lactams, fluoroquinolones, and aminoglycoside were found. The presence of T6SS in a mobile genetic element (plasmid suggests plausible horizontal transfer of these virulence genes to other organisms. The C. coli YH502 genome also harbors CRISPR sequences and associated proteins. Phylogenetic analysis based on average nucleotide identity and single nucleotide polymorphisms identified closely related C. coli genomes available in the NCBI database. Taken together, the analyzed genomic data of this potentially virulent strain of C. coli will facilitate further understanding of this important foodborne pathogen most likely leading to better control strategies. The chromosome and plasmid sequences of C. coli YH502 have been deposited in GenBank under the accession numbers CP018900.1 and CP018901.1, respectively.

  15. Iron Starvation Conditions Upregulate Ehrlichia ruminantium Type IV Secretion System, tr1 Transcription Factor and map1 Genes Family through the Master Regulatory Protein ErxR

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    Amal Moumène

    2018-01-01

    Full Text Available Ehrlichia ruminantium is an obligatory intracellular bacterium that causes heartwater, a fatal disease in ruminants. Due to its intracellular nature, E. ruminantium requires a set of specific virulence factors, such as the type IV secretion system (T4SS, and outer membrane proteins (Map proteins in order to avoid and subvert the host's immune response. Several studies have been conducted to understand the regulation of the T4SS or outer membrane proteins, in Ehrlichia, but no integrated approach has been used to understand the regulation of Ehrlichia pathogenicity determinants in response to environmental cues. Iron is known to be a key nutrient for bacterial growth both in the environment and within hosts. In this study, we experimentally demonstrated the regulation of virB, map1, and tr1 genes by the newly identified master regulator ErxR (for Ehrlichia ruminantium expression regulator. We also analyzed the effect of iron depletion on the expression of erxR gene, tr1 transcription factor, T4SS and map1 genes clusters in E. ruminantium. We show that exposure of E. ruminantium to iron starvation induces erxR and subsequently tr1, virB, and map1 genes. Our results reveal tight co-regulation of T4SS and map1 genes via the ErxR regulatory protein at the transcriptional level, and, for the first time link map genes to the virulence function sensu stricto, thereby advancing our understanding of Ehrlichia's infection process. These results suggest that Ehrlichia is able to sense changes in iron concentrations in the environment and to regulate the expression of virulence factors accordingly.

  16. Human Tear Fluid Reduces Culturability of Contact Lens Associated Pseudomonas aeruginosa Biofilms but Induces Expression of the Virulence Associated Type III Secretion System

    Science.gov (United States)

    Wu, Yvonne T.; Tam, Connie; Zhu, Lucia S.; Evans, David J.; Fleiszig, Suzanne M. J.

    2017-01-01

    Purpose The type III secretion system (T3SS) is a significant virulence determinant for Pseudomonas aeruginosa. Using a rodent model, we found that contact lens (CL)-related corneal infections were associated with lens surface biofilms. Here, we studied the impact of human tear fluid on CL-associated biofilm growth and T3SS expression. Methods P. aeruginosa biofilms were formed on contact lenses for up to 7 days with or without human tear fluid, then exposed to tear fluid for 5 or 24 h. Biofilms were imaged using confocal microscopy. Bacterial culturability was quantified by viable counts, and T3SS gene expression measured by RT-qPCR. Controls included trypticase soy broth, PBS and planktonic bacteria. Results With or without tear fluid, biofilms grew to ~108 cfu viable bacteria by 24 h. Exposing biofilms to tear fluid after they had formed without it on lenses reduced bacterial culturability ~180-fold (pbacteria [5.46 ± 0.24-fold for T3SS transcriptional activitor exsA (p=.02), and 3.76 ± 0.36-fold for T3SS effector toxin exoS (p=.01)]. Tear fluid further enhanced exsA and exoS expression in CL-grown biofilms, but not planktonic bacteria, by 2.09 ± 0.38-fold (p = 0.04) and 1.89 ± 0.26-fold (p<.001), respectively. Conclusions Considering the pivitol role of the T3SS in P. aeruginosa infections, its induction in CL-grown P. aeruginosa biofilms by tear fluid might contribute to the pathogenesis of CL-related P. aeruginosa keratitis. PMID:27670247

  17. Production of full length and splicing form of chymosin using pETexpression system in E-coli and investigation its enzyme activity and preplasmic secretion

    Directory of Open Access Journals (Sweden)

    M. Ahmadi Zeydabadi

    2008-05-01

    Full Text Available Introduction: Chymosin (Rennin EC 3.4.23.4 is an aspartyl proteinas (the major proteolyticenzyme in the fourth stomach of the unweaned calf that is formed by proteolytic activation fromzymogene prochymosin. The aim of his study was to produce the full length and splicing form ofchymosin using pETexpression system in E-coli and to assay the activity of expressed enzyme andpreplasmic secretion.Materials and Methods: The sense primer F-prochy(+ (5´-ggggccatgGCTGAGATCACCAGGAincluding NCOI restriction site. The anti sense R-prochy(- (5´-gggcggccgcGATGGCTTTGGCCAGC -3´ hybridizing to the C-terminal end of calf preprocymosincDNA and contains an additional NotI restriction site at its 5´-end . The cells were disrupted bysonication and proteins were purified by using Ni-NTA beads from Qiagen under native conditional.The preprochymosin and AS6 preprochymosin were activated at pH 4.7. The enzyme solutions werediluted 20-fold with 50 mM phosphate buffer .Results: Sequencing data analysis showed that the exon six has been spliced out and, therefore thegene product is 114 bp shorter in length, both chymosin forms were expressed together in E.coli.Under the same expression conditions, at least AS6 preprochymosin was produced 7-fold highexpression in comparison to a full-length recombinant chymosin. Following acid activation andneutralization, the purified fractions were tested in a qualitative milk clotting assay. The clottingactivity of preprochymosin and exon6-less preprochymosin were comparable.Conclusion: High expression of this alternatively expressed transcript in bacteria, and properfolding of the AS6 chymosin protein molecule in the absence of exon six are the two most importantaspects distinguished in this research.

  18. Proteins Related to the Type I Secretion System Are Associated with Secondary SecA_DEAD Domain Proteins in Some Species of Planctomycetes, Verrucomicrobia, Proteobacteria, Nitrospirae and Chlorobi.

    Directory of Open Access Journals (Sweden)

    Olga K Kamneva

    Full Text Available A number of bacteria belonging to the PVC (Planctomycetes-Verrucomicrobia-Chlamydiae super-phylum contain unusual ribosome-bearing intracellular membranes. The evolutionary origins and functions of these membranes are unknown. Some proteins putatively associated with the presence of intracellular membranes in PVC bacteria contain signal peptides. Signal peptides mark proteins for translocation across the cytoplasmic membrane in prokaryotes, and the membrane of the endoplasmic reticulum in eukaryotes, by highly conserved Sec machinery. This suggests that proteins might be targeted to intracellular membranes in PVC bacteria via the Sec pathway. Here, we show that canonical signal peptides are significantly over-represented in proteins preferentially present in PVC bacteria possessing intracellular membranes, indicating involvement of Sec translocase in their cellular targeting. We also characterized Sec proteins using comparative genomics approaches, focusing on the PVC super-phylum. While we were unable to detect unique changes in Sec proteins conserved among membrane-bearing PVC species, we identified (1 SecA ATPase domain re-arrangements in some Planctomycetes, and (2 secondary SecA_DEAD domain proteins in the genomes of some Planctomycetes, Verrucomicrobia, Proteobacteria, Nitrospirae and Chlorobi. This is the first report of potentially duplicated SecA in Gram-negative bacteria. The phylogenetic distribution of secondary SecA_DEAD domain proteins suggests that the presence of these proteins is not related to the occurrence of PVC endomembranes. Further genomic analysis showed that secondary SecA_DEAD domain proteins are located within genomic neighborhoods that also encode three proteins possessing domains specific for the Type I secretion system.

  19. In vitro expansion and differentiation of rat pancreatic duct-derived stem cells into insulin secreting cells using a dynamicthree-dimensional cell culture system.

    Science.gov (United States)

    Chen, X C; Liu, H; Li, H; Cheng, Y; Yang, L; Liu, Y F

    2016-06-27

    In this study, a dynamic three-dimensional cell culture technology was used to expand and differentiate rat pancreatic duct-derived stem cells (PDSCs) into islet-like cell clusters that can secrete insulin. PDSCs were isolated from rat pancreatic tissues by in situ collagenase digestion and density gradient centrifugation. Using a dynamic three-dimensional culture technique, the cells were expanded and differentiated into functional islet-like cell clusters, which were characterized by morphological and phenotype analyses. After maintaining 1 x 108 isolated rat PDSCs in a dynamic three-dimensional cell culture for 7 days, 1.5 x 109 cells could be harvested. Passaged PDSCs expressed markers of pancreatic endocrine progenitors, including CD29 (86.17%), CD73 (90.73%), CD90 (84.13%), CD105 (78.28%), and Pdx-1. Following 14 additional days of culture in serum-free medium with nicotinamide, keratinocyte growth factor (KGF), and b fibroblast growth factor (FGF), the cells were differentiated into islet-like cell clusters (ICCs). The ICC morphology reflected that of fused cell clusters. During the late stage of differentiation, representative clusters were non-adherent and expressed insulin indicated by dithizone (DTZ)-positive staining. Insulin was detected in the extracellular fluid and cytoplasm of ICCs after 14 days of differentiation. Additionally, insulin levels were significantly higher at this time compared with the levels exhibited by PDSCs before differentiation (P cell culture system, PDSCs can be expanded in vitro and can differentiate into functional islet-like cell clusters.

  20. Evolutionary Dynamics of Pathoadaptation Revealed by Three Independent Acquisitions of the VirB/D4 Type IV Secretion System in Bartonella.

    Science.gov (United States)

    Harms, Alexander; Segers, Francisca H I D; Quebatte, Maxime; Mistl, Claudia; Manfredi, Pablo; Körner, Jonas; Chomel, Bruno B; Kosoy, Michael; Maruyama, Soichi; Engel, Philipp; Dehio, Christoph

    2017-03-01

    The α-proteobacterial genus Bartonella comprises a group of ubiquitous mammalian pathogens that are studied as a model for the evolution of bacterial pathogenesis. Vast abundance of two particular phylogenetic lineages of Bartonella had been linked to enhanced host adaptability enabled by lineage-specific acquisition of a VirB/D4 type IV secretion system (T4SS) and parallel evolution of complex effector repertoires. However, the limited availability of genome sequences from one of those lineages as well as other, remote branches of Bartonella has so far hampered comprehensive understanding of how the VirB/D4 T4SS and its effectors called Beps have shaped Bartonella evolution. Here, we report the discovery of a third repertoire of Beps associated with the VirB/D4 T4SS of B. ancashensis, a novel human pathogen that lacks any signs of host adaptability and is only distantly related to the two species-rich lineages encoding a VirB/D4 T4SS. Furthermore, sequencing of ten new Bartonella isolates from under-sampled lineages enabled combined in silico analyses and wet lab experiments that suggest several parallel layers of functional diversification during evolution of the three Bep repertoires from a single ancestral effector. Our analyses show that the Beps of B. ancashensis share many features with the two other repertoires, but may represent a more ancestral state that has not yet unleashed the adaptive potential of such an effector set. We anticipate that the effectors of B. ancashensis will enable future studies to dissect the evolutionary history of Bartonella effectors and help unraveling the evolutionary forces underlying bacterial host adaptation. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  1. Lipids in airway secretions

    International Nuclear Information System (INIS)

    Bhaskar, K.R.; DeFeudis O'Sullivan, D.; Opaskar-Hincman, H.; Reid, L.M.

    1987-01-01

    Lipids form a significant portion of airway mucus yet they have not received the same attention that epithelial glycoproteins have. We have analysed, by thin layer chromatography, lipids present in airway mucus under 'normal' and hypersecretory (pathological) conditions.The 'normals' included (1) bronchial lavage obtained from healthy human volunteers and from dogs and (2) secretions produced ''in vitro'' by human (bronchial) and canine (tracheal) explants. Hypersecretory mucus samples included (1) lavage from dogs made bronchitic by exposure to SO 2 , (2) bronchial aspirates from acute and chronic tracheostomy patients, (3) sputum from patients with cystic fibrosis and chronic bronchitis and (4) postmortem secretions from patients who died from sudden infant death syndrome (SIDS) or from status asthmaticus. Cholesterol was found to be the predominant lipid in 'normal' mucus with lesser amounts of phospholipids. No glycolipids were detected. In the hypersecretory mucus, in addition to neutral and phospholipids, glycolipids were present in appreciable amounts, often the predominant species, suggesting that these may be useful as markers of disease. Radioactive precursors 14 C acetate and 14 C palmitate were incorporated into lipids secreted ''in vitro'' by canine tracheal explants indicating that they are synthesised by the airway. (author)

  2. Sagnac secret sharing over telecom fiber networks.

    Science.gov (United States)

    Bogdanski, Jan; Ahrens, Johan; Bourennane, Mohamed

    2009-01-19

    We report the first Sagnac quantum secret sharing (in three-and four-party implementations) over 1550 nm single mode fiber (SMF) networks, using a single qubit protocol with phase encoding. Our secret sharing experiment has been based on a single qubit protocol, which has opened the door to practical secret sharing implementation over fiber telecom channels and in free-space. The previous quantum secret sharing proposals were based on multiparticle entangled states, difficult in the practical implementation and not scalable. Our experimental data in the three-party implementation show stable (in regards to birefringence drift) quantum secret sharing transmissions at the total Sagnac transmission loop distances of 55-75 km with the quantum bit error rates (QBER) of 2.3-2.4% for the mean photon number micro?= 0.1 and 1.7-2.1% for micro= 0.3. In the four-party case we have achieved quantum secret sharing transmissions at the total Sagnac transmission loop distances of 45-55 km with the quantum bit error rates (QBER) of 3.0-3.7% for the mean photon number micro= 0.1 and 1.8-3.0% for micro?= 0.3. The stability of quantum transmission has been achieved thanks to our new concept for compensation of SMF birefringence effects in Sagnac, based on a polarization control system and a polarization insensitive phase modulator. The measurement results have showed feasibility of quantum secret sharing over telecom fiber networks in Sagnac configuration, using standard fiber telecom components.

  3. Central nervous system neuropeptide Y regulates mediators of hepatic phospholipid remodeling and very low-density lipoprotein triglyceride secretion via sympathetic innervation

    NARCIS (Netherlands)

    Rojas, Jennifer M; Bruinstroop, E.; Printz, Richard L; Alijagic-Boers, Aldijana; Foppen, E.; Turney, Maxine K; George, Leena; Beck-Sickinger, Annette G; Kalsbeek, A.; Niswender, Kevin D

    OBJECTIVE: Elevated very low-density lipoprotein (VLDL)-triglyceride (TG) secretion from the liver contributes to an atherogenic dyslipidemia that is associated with obesity, diabetes and the metabolic syndrome. Numerous models of obesity and diabetes are characterized by increased central nervous

  4. Central nervous system neuropeptide Y regulates mediators of hepatic phospholipid remodeling and very low-density lipoprotein triglyceride secretion via sympathetic innervation

    NARCIS (Netherlands)

    Rojas, Jennifer M.; Bruinstroop, Eveline; Printz, Richard L.; Alijagic-Boers, Aldijana; Foppen, Ewout; Turney, Maxine K.; George, Leena; Beck-Sickinger, Annette G.; Kalsbeek, Andries; Niswender, Kevin D.

    2015-01-01

    Objective: Elevated very low-density lipoprotein (VLDL)-triglyceride (TG) secretion from the liver contributes to an atherogenic dyslipidemia that is associated with obesity, diabetes and the metabolic syndrome. Numerous models of obesity and diabetes are characterized by increased central nervous

  5. AtlA Functions as a Peptidoglycan Lytic Transglycosylase in the Neisseria gonorrhoeae Type IV Secretion System▿

    OpenAIRE

    Kohler, Petra L.; Hamilton, Holly L.; Cloud-Hansen, Karen; Dillard, Joseph P.

    2007-01-01

    Type IV secretion systems require peptidoglycan lytic transglycosylases for efficient secretion, but the function of these enzymes is not clear. The type IV secretion system gene cluster of Neisseria gonorrhoeae encodes two peptidoglycan transglycosylase homologues. One, LtgX, is similar to peptidoglycan transglycosylases from other type IV secretion systems. The other, AtlA, is similar to endolysins from bacteriophages and is not similar to any described type IV secretion component. We chara...

  6. Comment on "Dynamic quantum secret sharing"

    Science.gov (United States)

    Liao, Ci-Hong; Yang, Chun-Wei; Hwang, Tzonelish

    2013-10-01

    Hsu et al. (Quantum Inf Process 12:331-344,2013) proposed a dynamic quantum secret sharing (DQSS) protocol using the entanglement swapping of Bell states for an agent to easily join (or leave) the system. In 2013, Wang and Li (Quantum Inf Process 12(5):1991-1997, 2013) proposed a collusion attack on Hsu et al.'s DQSS protocol. Nevertheless, this study points out a new security issue on Hsu et al.'s DQSS protocol regarding to the honesty of a revoked agent. Without considering this issue, the DQSS protocol could be failed to provide secret sharing function.

  7. The Role of RaxST, a Prokaryotic Sulfotransferase, and RaxABC, a Putative Type I Secretion System, in Activation of the Rice XA21-Mediated Immune Response

    Directory of Open Access Journals (Sweden)

    Pamela C. Ronald

    2014-01-01

    Full Text Available Tyrosine sulfation is an important posttranslational modification that determines the outcome of serious diseases in plants and animals. We have recently demonstrated that the plant pathogen Xanthomonas oryzae pv. oryzae (Xoo carries a functional sulfotransferase (RaxST. raxST is required for activation of rice Xa21-mediated immunity indicating the critical, but unknown, function of raxST in mediating the Xoo/rice interaction. The raxST gene resides in the same operon (raxSTAB as components of a predicted type I secretion and processing system (RaxA and RaxB. These observations suggest a model where RaxST sulfates a molecule that contains a leader peptide, which is cleaved by the peptidase domain of the RaxB protein and secreted outside the bacterial cell by the RaxABC T1SS.

  8. Standpoints and protection of business secrets

    Directory of Open Access Journals (Sweden)

    Brane Bertoncelj

    2001-06-01

    Full Text Available The human impact on an information system where data bases, containing business secretes, are stored is one of the most unreliable and unforeseeable factors. For this reason, it must not be underestimated. The results of this study indicate a correlation between behavioural intention and protection of business secretes. There is a statistically significant correlation between behavioural intention and behavioural supervision. This means that an increased level of perceived supervision over one's own behaviour is related to behavioural intention. A great majority of participants would not divulge a business secret due to internal moral factors, i.e., they possess the appropriate capabilities to determine the advantages of social moral values over personal values.

  9. Type V secretion: From biogenesis to biotechnology

    NARCIS (Netherlands)

    van Ulsen, P.; Rahman, S.U.; Jong, W.S.P.; Daleke, M.H.; Luirink, J.

    2014-01-01

    The two membranes of Gram-negative bacteria contain protein machines that have a general function in their assembly. To interact with the extra-cellular milieu, Gram-negatives target proteins to their cell surface and beyond. Many specialized secretion systems have evolved with dedicated

  10. Intradermal delivery of Shigella IpaB and IpaD type III secretion proteins: kinetics of cell recruitment and antigen uptake, mucosal and systemic immunity, and protection across serotypes.

    Science.gov (United States)

    Heine, Shannon J; Diaz-McNair, Jovita; Andar, Abhay U; Drachenberg, Cinthia B; van de Verg, Lillian; Walker, Richard; Picking, Wendy L; Pasetti, Marcela F

    2014-02-15

    Shigella is one of the leading pathogens contributing to the vast pediatric diarrheal disease burden in low-income countries. No licensed vaccine is available, and the existing candidates are only partially effective and serotype specific. Shigella type III secretion system proteins IpaB and IpaD, which are conserved across Shigella spp., are candidates for a broadly protective, subunit-based vaccine. In this study, we investigated the immunogenicity and protective efficacy of IpaB and IpaD administered intradermally (i.d.) with a double-mutant of the Escherichia coli heat-labile enterotoxin (dmLT) adjuvant using microneedles. Different dosage levels of IpaB and IpaD, with or without dmLT, were tested in mice. Vaccine delivery into the dermis, recruitment of neutrophils, macrophages, dendritic cells, and Langerhans cells, and colocalization of vaccine Ag within skin-activated APC were demonstrated through histology and immunofluorescence microscopy. Ag-loaded neutrophils, macrophages, dendritic cells, and Langerhans cells remained in the tissue at least 1 wk. IpaB, IpaD, and dmLT-specific serum IgG- and IgG-secreting cells were produced following i.d. immunization. The protective efficacy was 70% against Shigella flexneri and 50% against Shigella sonnei. Similar results were obtained when the vaccine was administered intranasally, with the i.d. route requiring 25-40 times lower doses. Distinctively, IgG was detected in mucosal secretions; secretory IgA, as well as mucosal and systemic IgA Ab-secreting cells, were seemingly absent. Vaccine-induced T cells produced IFN-γ, IL-2, TNF-α, IL-17, IL-4, IL-5, and IL-10. These results demonstrate the potential of i.d. vaccination with IpaB and IpaD to prevent Shigella infection and support further studies in humans.

  11. Renal renin secretion as regulator of body fluid homeostasis

    DEFF Research Database (Denmark)

    Damkjær, Mads; Isaksson, Gustaf L; Stubbe, Jane

    2013-01-01

    The renin-angiotensin system is essential for body fluid homeostasis and blood pressure regulation. This review focuses on the homeostatic regulation of the secretion of active renin in the kidney, primarily in humans. Under physiological conditions, renin secretion is determined mainly by sodium...

  12. Characterization of Pseudomonas aeruginosa Chitinase, a Gradually Secreted Protein

    NARCIS (Netherlands)

    Folders, J. (Jindra); Algra, J. (Jon); Roelofs, M.S. (Marc); Loon, L.C. van; Tommassen, J.P.M.; Bitter, Wilbert

    2001-01-01

    The gram-negative bacterium Pseudomonas aeruginosa secretes many proteins into its extracellular environment via the type I, II, and III secretion systems. In this study, a gene, chiC, coding for an extracellular chitinolytic enzyme, was identified. The chiC gene encodes a polypeptide of 483 amino

  13. Molecular epidemiological survey of the quinolone- and carbapenem-resistant genotype and its association with the type III secretion system in Pseudomonas aeruginosa.

    Science.gov (United States)

    Ferreira, Melina Lorraine; Dantas, Raquel Cavalcanti; Faria, Ana Luiza Souza; Gonçalves, Iara Rossi; Silveira de Brito, Cristiane; Queiroz, Lícia Ludendorff; Gontijo-Filho, Paulo P; Ribas, Rosineide Marques

    2015-03-01

    This study evaluated the predictors of mortality and the impact of inappropriate therapy on the outcomes of patients with bacteraemia and ventilator-associated pneumonia (VAP). Additionally, we evaluated the correlation of the type III secretion system (TTSS) effector genotype with resistance to carbapenems and fluoroquinolones, mutations in the quinolone resistance-determining regions (QRDRs), metallo-β-lactamase and virulence factors. A retrospective cohort was conducted at a tertiary hospital in patients with multidrug-resistant (MDR) P. aeruginosa bacteraemia (157 patients) and VAP (60 patients). The genes for blaIMP, blaVIM, blaSIM, blaGIM and blaSPM and virulence genes (exoT, exoS, exoY, exoU, lasB, algD and toxA) were detected; sequencing was conducted for QRDR genes on fluoroquinolone-resistant strains. The multivariate analyses showed that the predictors independently associated with death in patients with bacteraemia were cancer and inappropriate therapy. Carbapenem resistance was more frequent among strains causing VAP (53.3 %), and in blood we observed the blaSPM genotype (66.6 %) and blaVIM genotype (33.3 %). The exoS gene was found in all isolates, whilst the frequency was low for exoU (9.4 %). Substitution of threonine to isoleucine at position 83 in gyrA was the most frequent mutation among fluoroquinolone-resistant strains. Our study showed a mutation at position 91 in the parC gene (Glu91Lys) associated with a mutation in gyrA (Thre83Ile) in a strain of extensively drug-resistant P. aeruginosa, with the exoT(+)exoS(+)exoU(+) genotype, that has not yet been described in Brazil to the best of our knowledge. This comprehensive analysis of resistance mechanisms to carbapenem and fluoroquinolones and their association with TTSS virulence genes, covering MDR P. aeruginosa in Brazil, is the largest reported to date. © 2015 The Authors.

  14. On Converting Secret Sharing Scheme to Visual Secret Sharing Scheme

    Directory of Open Access Journals (Sweden)

    Wang Daoshun

    2010-01-01

    Full Text Available Abstract Traditional Secret Sharing (SS schemes reconstruct secret exactly the same as the original one but involve complex computation. Visual Secret Sharing (VSS schemes decode the secret without computation, but each share is m times as big as the original and the quality of the reconstructed secret image is reduced. Probabilistic visual secret sharing (Prob.VSS schemes for a binary image use only one subpixel to share the secret image; however the probability of white pixels in a white area is higher than that in a black area in the reconstructed secret image. SS schemes, VSS schemes, and Prob. VSS schemes have various construction methods and advantages. This paper first presents an approach to convert (transform a -SS scheme to a -VSS scheme for greyscale images. The generation of the shadow images (shares is based on Boolean XOR operation. The secret image can be reconstructed directly by performing Boolean OR operation, as in most conventional VSS schemes. Its pixel expansion is significantly smaller than that of VSS schemes. The quality of the reconstructed images, measured by average contrast, is the same as VSS schemes. Then a novel matrix-concatenation approach is used to extend the greyscale -SS scheme to a more general case of greyscale -VSS scheme.

  15. Sweet taste receptor expressed in pancreatic beta-cells activates the calcium and cyclic AMP signaling systems and stimulates insulin secretion.

    Directory of Open Access Journals (Sweden)

    Yuko Nakagawa

    Full Text Available BACKGROUND: Sweet taste receptor is expressed in the taste buds and enteroendocrine cells acting as a sugar sensor. We investigated the expression and function of the sweet taste receptor in MIN6 cells and mouse islets. METHODOLOGY/PRINCIPAL FINDINGS: The expression of the sweet taste receptor was determined by RT-PCR and immunohistochemistry. Changes in cytoplasmic Ca(2+ ([Ca(2+](c and cAMP ([cAMP](c were monitored in MIN6 cells using fura-2 and Epac1-camps. Activation of protein kinase C was monitored by measuring translocation of MARCKS-GFP. Insulin was measured by radioimmunoassay. mRNA for T1R2, T1R3, and gustducin was expressed in MIN6 cells. In these cells, artificial sweeteners such as sucralose, succharin, and acesulfame-K increased insulin secretion and augmented secretion induced by glucose. Sucralose increased biphasic increase in [Ca(2+](c. The second sustained phase was blocked by removal of extracellular calcium and addition of nifedipine. An inhibitor of inositol(1, 4, 5-trisphophate receptor, 2-aminoethoxydiphenyl borate, blocked both phases of [Ca(2+](c response. The effect of sucralose on [Ca(2+](c was inhibited by gurmarin, an inhibitor of the sweet taste receptor, but not affected by a G(q inhibitor. Sucralose also induced sustained elevation of [cAMP](c, which was only partially inhibited by removal of extracellular calcium and nifedipine. Finally, mouse islets expressed T1R2 and T1R3, and artificial sweeteners stimulated insulin secretion. CONCLUSIONS: Sweet taste receptor is expressed in beta-cells, and activation of this receptor induces insulin secretion by Ca(2+ and cAMP-dependent mechanisms.

  16. The involvement of dopaminergic system on LH secretion Nelore heifers Sistema dopaminérgico na secreção de LH de novilhas Nelore

    Directory of Open Access Journals (Sweden)

    Silvia Helena Venturoli Perri

    2009-12-01

    Full Text Available The aim of this study was to evaluate the response of sulpiride administration (dopamine D2 antagonist, 0.59 m/kg body weight, s.c. and blood collected every 15 min for 10 h thereafter on Luteinizing Hormone (LH secretion in B. indicus pre-pubertal heifers at 8, 12 and 16 month of age. LH was quantified by RIA, sensitivity (0.039 ng/ml and CV (15.51%. In heifers given sulpiride treatment didn’t differ (P≥0.05 in LH concentration, total secretion area, peak total area, number of peaks, area of highest secretion peak and time to highest peak occurrence and maximum LH secretion, from control group. The results suggest absence of dopamine D2 antagonist effect on LH secretion in pre-pubertal Nellore heifers, didn’t neurotransmitter participating on sexual maturation.O presente trabalho foi realizado com o objetivo de investigar a variação na secreção do Hormônio Luteinizante (LH em resposta ao tratamento com sulpiride, antagonista de receptor (D2 dopaminérgico, com administração de 0,59mg/kg, s.c. e colheita de amostras de sangue a cada 15min, por 10h. Foram utilizadas 10 novilhas da raça Nelore pré-púberes, aos 8, 12 e 16 meses de idade. A concentração de LH foi quantificada por radioimunoensaio, e o coeficiente de variação intra, o interensaio e a sensibilidade dos ensaios de LH foram respectivamente de: 11,86%; 15,51%; 0,039ng/mL. O tratamento com sulpiride não diferiu na concentração média de LH, área total de secreção de LH e picos, número de picos, área do maior pico, tempo necessário ao aparecimento do maior pico de secreção de LH e amplitude máxima de LH, em comparação ao grupo controle. Os resultados indicam ausência de efeito da dopamina, através de receptores D2, durante a fase pré-púbere, em novilhas da raça Nelore, o que sinaliza a não participação como neurotransmissora na secreção de LH durante o processo de maturação sexual.

  17. The Ca2+ induced two-component system, CvsSR regulates the Type III secretion system and the extracytoplasmic function sigma-factor AlgU in Pseudomonas syringae pv. tomato DC3000.

    Science.gov (United States)

    Fishman, Maxwell R; Zhang, Johnson; Bronstein, Philip A; Stodghill, Paul; Filiatrault, Melanie J

    2017-12-20

    Two-component systems (TCSs) of bacteria regulate many different aspects of the bacterial life cycle including pathogenesis. Most TCSs remain uncharacterized with no information about the signal(s) or regulatory targets and/or role in bacterial pathogenesis. Here, we characterized a TCS in the plant-pathogenic bacterium Pseudomonas syringae pv. tomato DC3000 ( Pto ) composed of the histidine kinase, CvsS, and the response regulator, CvsR. CvsSR is necessary for virulence of Pto , since ΔcvsS and ΔcvsR strains produced fewer symptoms and demonstrated reduced growth on multiple hosts as compared to WT. We discovered that expression of cvsSR is induced by Ca 2+ concentrations found in leaf apoplastic fluid. Thus, Ca 2+ can be added to the list of signals that promote pathogenesis of Pto during host colonization. Through chromatin immunoprecipitation followed by next generation sequencing (ChIP-seq) and global transcriptome analysis (RNA-seq) we discerned the CvsR regulon. CvsR directly activated expression of the type III secretion system regulators, hrpR and hrpS , that regulates Pto virulence in a type III secretion system dependent manner. CvsR also indirectly repressed transcription of the extracytoplasmic sigma factor algU and production of alginate. Phenotypic analysis determined that CvsSR inversely regulated biofilm formation, swarming motility, and cellulose production in a Ca 2+ -dependent manner. Overall, our results show that CvsSR is a key regulatory hub critical for interaction with host plants. Importance Pathogenic bacteria must be able to react and respond to the surrounding environment, make use of available resources, and avert or counter host immune responses. Often, these abilities rely on two-component systems (TCSs) composed of interacting proteins that modulate gene expression. We identified a TCS in the plant-pathogenic bacterium Pseudomonas syringae that responds to the presence of calcium, which is an important signal during the plant

  18. Secret and research

    Directory of Open Access Journals (Sweden)

    André PETITAT

    2013-12-01

    Full Text Available The postures of secrecy and revelation maintain our common relational dynamics between sharing and not sharing. Science, which has become the dominant form of knowledge, is a rational and empirical knowledge sharing. For this purpose, the knowledge articulates languages, if possible unambiguous, spaces of rational deliberation, technical devices and resources of the imagination. This activity meets other logics called power, prestige, status, profit, customer, blind adherence and revealed truth, in which the postures of secret invite themselves massively. The codes of ethics attempt to regulate this mix of contradictory logics by setting standards of scientific exchanges, recalling the person rights and particularly the subjects observed rights, protecting the working conditions of the researcher, preserving its autonomy from funders and policy makers, and ensuring the dissemination of its results.

  19. Ability of multicellular salt glands in Tamarix species to secrete Na+ and K+ selectively.

    Science.gov (United States)

    Ma, Haiyan; Tian, Changyan; Feng, Gu; Yuan, Junfeng

    2011-03-01

    The present study aimed to determine the mechanism of cation-selective secretion by multicellular salt glands. Using a hydroponic culture system, the secretion and accumulation of Na(+) and K(+) in Tamarix ramosissima and T. laxa under different salt stresses (NaCl, KCl and NaCl+KCl) were studied. Additionally, the effects of salt gland inhibitors (orthovanadate, Ba(2+), ouabain, tetraethylammonium (TEA) and verapamil) on Na(+) and K(+) secretion and accumulation were examined. Treatment with NaCl (at 0-200 mmol L(-1) levels) significantly increased Na(+) secretion, whereas KCl treatment (at 0-200 mmol L(-1) levels) significantly increased K(+) secretion. The ratio of secretion to accumulation of Na(+) was higher than that of K(+). The changes in Na(+) and K(+) secretion differed after adding different ions into the single-salt solutions. Addition of NaCl to the KCl solution (at 100 mmol L(-1) level, respectively) led to a significant decrease in K(+) secretion rate, whereas addition of KCl to the NaCl solution (at 100 mmol L(-1) level, respectively) had little impact on the Na(+) secretion rate. These results indicated that Na+ secretion in Tamarix was highly selective. In addition, Na(+) secretion was significantly inhibited by orthovanadate, ouabain, TEA and verapamil, and K(+) secretion was significantly inhibited by ouabain, TEA and verapamil. The different impacts of orthovanadate on Na(+) and K(+) secretion might be the primary cause for the different Na(+) and K(+) secretion abilities of multicellular salt glands in Tamarix.

  20. Secret key distillation from shielded two-qubit states

    International Nuclear Information System (INIS)

    Bae, Joonwoo

    2010-01-01

    The quantum states corresponding to a secret key are characterized using the so-called private states, where the key part consisting of a secret key is shielded by the additional systems. Based on the construction, it was shown that a secret key can be distilled from bound entangled states. In this work, I consider the shielded two-qubit states in a key-distillation scenario and derive the conditions under which a secret key can be distilled using the recurrence protocol or the two-way classical distillation, advantage distillation together with one-way postprocessing. From the security conditions, it is shown that a secret key can be distilled from bound entangled states in a much wider range. In addition, I consider the case that in which white noise is added to quantum states and show that the classical distillation protocol still works despite a certain amount of noise although the recurrence protocol does not.

  1. Proprotein Convertases Process Pmel17 during Secretion*

    Science.gov (United States)

    Leonhardt, Ralf M.; Vigneron, Nathalie; Rahner, Christoph; Cresswell, Peter

    2011-01-01

    Pmel17 is a melanocyte/melanoma-specific protein that traffics to melanosomes where it forms a fibrillar matrix on which melanin gets deposited. Before being cleaved into smaller fibrillogenic fragments the protein undergoes processing by proprotein convertases, a class of serine proteases that typically recognize the canonical motif RX(R/K)R↓. The current model of Pmel17 maturation states that this processing step occurs in melanosomes, but in light of recent reports this issue has become controversial. We therefore addressed this question by thoroughly assessing the processing kinetics of either wild-type Pmel17 or a secreted soluble Pmel17 derivative. Our results demonstrate clearly that processing of Pmel17 occurs during secretion and that it does not require entry of the protein into the endocytic system. Strikingly, processing proceeds even in the presence of the secretion inhibitor monensin, suggesting that Pmel17 is an exceptionally good substrate. In line with this, we find that newly synthesized surface Pmel17 is already quantitatively cleaved. Moreover, we demonstrate that Pmel17 function is independent of the sequence identity of its unconventional proprotein convertase-cleavage motif that lacks arginine in P4 position. The data alter the current view of Pmel17 maturation and suggest that the multistep processing of Pmel17 begins with an early cleavage during secretion that primes the protein for later functional processing. PMID:21247888

  2. Constitutive protein secretion from the exocrine pancreas of fetal rats

    International Nuclear Information System (INIS)

    Arvan, P.; Chang, A.

    1987-01-01

    Two general kinds of exocytotic secretion of proteins are known: that which is stimulated by secretagogues; and constitutive exocytosis, which is unable to be stimulated. The exocrine pancreas has often been cited as a model system for the first kind of secretion. However, the release of digestive enzymes from the exocrine pancreas of 1-day prenatal rats cannot be stimulated by secretagogues; therefore, its secretion is constitutive. To gain insight into the intracellular pathways which mediate secretion in the fetal gland, we examined the kinetics of release of newly synthesized proteins. We find that fetal pancreas in a steady state of secretion releases pulse-labeled secretory proteins in two kinetically distinct phases. The first phase occurring during 0-6.5 h of chase comprises approximately 12% of total incorporated radioactivity, the second phase beginning at greater than 7 h of chase comprises the remainder. Based on analysis by electron microscope autoradiography, radiolabel is localized during the first phase of secretion in immature granules/condensing vacuoles, Golgi compartments, and few mature granules. The second phase of secretion occurs when radiolabel is predominantly in mature granules. We propose that secretion occurs via (at least) 2 exocytotic routes, both of which are constitutive in fetal pancreatic tissue

  3. Pheochromocytomas and secreting paragangliomas

    Directory of Open Access Journals (Sweden)

    Gimenez-Roqueplo Anne-Paule

    2006-12-01

    Full Text Available Abstract Catecholamine-producing tumors may arise in the adrenal medulla (pheochromocytomas or in extraadrenal chromaffin cells (secreting paragangliomas. Their prevalence is about 0.1% in patients with hypertension and 4% in patients with a fortuitously discovered adrenal mass. An increase in the production of catecholamines causes symptoms (mainly headaches, palpitations and excess sweating and signs (mainly hypertension, weight loss and diabetes reflecting the effects of epinephrine and norepinephrine on α- and β-adrenergic receptors. Catecholamine-producing tumors mimic paroxysmal conditions with hypertension and/or cardiac rhythm disorders, including panic attacks, in which sympathetic activation linked to anxiety reproduces the same signs and symptoms. These tumors may be sporadic or part of any of several genetic diseases: familial pheochromocytoma-paraganglioma syndromes, multiple endocrine neoplasia type 2, neurofibromatosis 1 and von Hippel-Lindau disease. Familial cases are diagnosed earlier and are more frequently bilateral and recurring than sporadic cases. The most specific and sensitive diagnostic test for the tumor is the determination of plasma or urinary metanephrines. The tumor can be located by computed tomography, magnetic resonance imaging and metaiodobenzylguanidine scintigraphy. Treatment requires resection of the tumor, generally by laparoscopic surgery. About 10% of tumors are malignant either at first operation or during follow-up, malignancy being diagnosed by the presence of lymph node, visceral or bone metastases. Recurrences and malignancy are more frequent in cases with large or extraadrenal tumors. Patients, especially those with familial or extraadrenal tumors, should be followed-up indefinitely.

  4. The PorX response regulator of the Porphyromonas gingivalis PorXY two-component system does not directly regulate the Type IX secretion genes but binds the PorL subunit.

    Directory of Open Access Journals (Sweden)

    Maxence S Vincent

    2016-08-01

    Full Text Available The Type IX secretion system (T9SS is a versatile multi-protein complex restricted to bacteria of the Bacteriodetes phylum and responsible for the secretion of surface attachment of diverse proteins that participate to S-layer formation, gliding motility or pathogenesis. The T9SS is poorly characterized but a number of proteins involved in the assembly of the secretion apparatus in the oral pathogen Porphyromonas gingivalis have been identified based on genome substractive analyses. Among these proteins, PorY and PorX encode typical two-component system (TCS sensor and CheY-like response regulator respectively. Although the porX and porY genes do not localize at the same genetic locus, it has been proposed that PorXY form a bona fide TCS. Deletion of the porX in P. gingivalis causes a slight decrease of the expression of a number of other T9SS genes, including sov, porT, porP, porK, porL, porM, porN and porY. Here, we show that PorX and the soluble cytoplasmic domain of PorY interact. Using electrophoretic mobility shift, DNA-protein co-purification and heterologous host expression assays, we showed that PorX does not bind and does not directly regulate expression of the T9SS genes. Finally, we show that PorX interacts with the cytoplasmic domain of PorL, a component of the T9SS membrane core complex and propose that the CheY-like PorX protein might be involved in the dynamics of the T9SS.

  5. The PorX Response Regulator of the Porphyromonas gingivalis PorXY Two-Component System Does Not Directly Regulate the Type IX Secretion Genes but Binds the PorL Subunit

    Science.gov (United States)

    Vincent, Maxence S.; Durand, Eric; Cascales, Eric

    2016-01-01

    The Type IX secretion system (T9SS) is a versatile multi-protein complex restricted to bacteria of the Bacteriodetes phylum and responsible for the secretion or cell surface exposition of diverse proteins that participate to S-layer formation, gliding motility or pathogenesis. The T9SS is poorly characterized but a number of proteins involved in the assembly of the secretion apparatus in the oral pathogen Porphyromonas gingivalis have been identified based on genome substractive analyses. Among these proteins, PorY, and PorX encode typical two-component system (TCS) sensor and CheY-like response regulator respectively. Although the porX and porY genes do not localize at the same genetic locus, it has been proposed that PorXY form a bona fide TCS. Deletion of porX in P. gingivalis causes a slight decrease of the expression of a number of other T9SS genes, including sov, porT, porP, porK, porL, porM, porN, and porY. Here, we show that PorX and the soluble cytoplasmic domain of PorY interact. Using electrophoretic mobility shift, DNA-protein co-purification and heterologous host expression assays, we demonstrate that PorX does not bind T9SS gene promoters and does not directly regulate expression of the T9SS genes. Finally, we show that PorX interacts with the cytoplasmic domain of PorL, a component of the T9SS membrane core complex and propose that the CheY-like PorX protein might be involved in the dynamics of the T9SS. PMID:27630829

  6. Analysis of Erwinia chrysanthemi EC16 pelE::uidA, pelL::uidA, and hrpN::uidA mutants reveals strain-specific atypical regulation of the Hrp type III secretion system.

    Science.gov (United States)

    Ham, Jong Hyun; Cui, Yaya; Alfano, James R; Rodríguez-Palenzuela, Pablo; Rojas, Clemencia M; Chatterjee, Arun K; Collmer, Alan

    2004-02-01

    The plant pathogen Erwinia chrysanthemi produces a variety of factors that have been implicated in its ability to cause soft-rot diseases in various hosts. These include HrpN, a harpin secreted by the Hrp type III secretion system; PelE, one of several major pectate lyase isozymes secreted by the type II system; and PelL, one of several secondary Pels secreted by the type II system. We investigated these factors in E. chrysanthemi EC16 with respect to the effects of medium composition and growth phase on gene expression (as determined with uidA fusions and Northern analyses) and effects on virulence. pelE was induced by polygalacturonic acid, but pelL was not, and hrpN was expressed unexpectedly in nutrient-rich King's medium B and in minimal salts medium at neutral pH. In contrast, the effect of medium composition on hrp expression in E. chrysanthemi CUCPB1237 and 3937 was like that of many other phytopathogenic bacteria in being repressed in complex media and induced in acidic pH minimal medium. Northern blot analysis of hrpN and hrpL expression by the wild-type and hrpL::omegaCmr and hrpS::omegaCmr mutants revealed that hrpN expression was dependent on the HrpL alternative sigma factor, whose expression, in turn, was dependent on the HrpS putative sigma54 enhancer binding protein. The expression of pelE and hrpN increased strongly in late logarithmic growth phase. To test the possible role of quorum sensing in this expression pattern, the expI/expR locus was cloned in Escherichia coli on the basis of its ability to direct production of acyl-homoserine lactone and then used to construct expI mutations in pelE::uidA, pelL::uidA, and hrpN::uidA Erwinia chrysanthemi strains. Mutation of expI had no apparent effect on the growth-phase-dependent expression of hrpN and pelE, or on the virulence of E. chrysanthemi in witloof chicory leaves. Overexpression of hrpN in E. chrysanthemi resulted in approximately 50% reduction of lesion size on chicory leaves without an

  7. The Secret of Future Victories

    Science.gov (United States)

    1992-02-01

    Copy S of 320 copies AD--A25 0 718 IDA PAPER P-265 3 THE SECRET OF FUTURE VICTORIES Paul F. Gormnan General, USA (Retired) DTIC 05M February 1992 NAY...TYPE AND DATES COVERED IFebruary 1992 Final--June 1991-January 1992 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS The Secret of Future Victories C -MDA...8 2N0-102 IDA PAPER P-2653 THE SECRET OF FUTURE VICTORIES Paul F. Gorman General. LUSA (Retired) February 1992 Approved for public release

  8. Induction of a hypothyroid state during juvenile development delays pubertal reactivation of the neuroendocrine system governing luteinising hormone secretion in the male rhesus monkey (Macaca mulatta).

    Science.gov (United States)

    Mann, D R; Bhat, G K; Stah, C D; Pohl, C R; Plant, T M

    2006-09-01

    The present study aimed to determine the influence of thyroid status on the timing of the pubertal resurgence in gonadotrophin-releasing hormone pulse generator activity [tracked by circulating luteinising hormone (LH) levels] in male rhesus monkeys. Six juvenile monkeys were orchidectomised and then treated with the antithyroid drug, methimazole, from 15-19 months until 36 months of age, at which time thyroxine (T(4)) replacement was initiated. Four additional agonadal monkeys served as controls. Blood samples were drawn weekly for hormonal assessments. Body weight, crown-rump length and bone age were monitored at regular intervals. By 8 weeks of methimazole treatment, plasma T(4) had fallen sharply, and the decline was associated with a plasma thyroid-stimulating hormone increase. In controls, plasma LH levels remained undetectable until the pubertal rise occurred at 29.3 +/- 0.2 months of age. This developmental event occurred in only half of the methimazole-treated animals before 36 months of age when T(4) replacement was initiated. The hypothyroid state was associated with a profound arrest of growth and bone maturation, but increased body mass indices and plasma leptin levels. T(4) replacement in methimazole-treated monkeys was associated with the pubertal rise in LH in the remaining three animals and accelerated somatic development in all six animals. Although pubertal resurgence in LH secretion occurred at a later chronological age in methimazole-treated animals compared to controls, bone age, crown-rump length and body weight at that time did not differ between groups. There were no long-term differences in plasma prolactin between groups. We conclude that juvenile hypothyroidism in male primates causes a marked delay in the pubertal resurgence of LH secretion, probably occasioned at the hypothalamic level. Whether this effect is meditated by an action of thyroid hormone directly on the hypothalamus or indirectly as a result of the concomitant deficit in

  9. Nonlinear secret image sharing scheme.

    Science.gov (United States)

    Shin, Sang-Ho; Lee, Gil-Je; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2 m⌉ bit-per-pixel (bpp), respectively.

  10. The Bordetella pertussis Type III Secretion System Tip Complex Protein Bsp22 Is Not a Protective Antigen and Fails To Elicit Serum Antibody Responses during Infection of Humans and Mice

    Science.gov (United States)

    Villarino Romero, Rodrigo; Bibova, Ilona; Cerny, Ondrej; Vecerek, Branislav; Wald, Tomas; Benada, Oldrich; Zavadilova, Jana; Sebo, Peter

    2013-01-01

    The type III secretion system (T3SS) of pathogenic bordetellae employs a self-associating tip complex protein Bsp22. This protein is immunogenic during infections by Bordetella bronchiseptica and could be used as a protective antigen to immunize mice against B. bronchiseptica challenge. Since low-passage clinical isolates of the human pathogen Bordetella pertussis produce a highly homologous Bsp22 protein (97% homology), we examined its vaccine and diagnostic potential. No Bsp22-specific antibodies were, however, detected in serum samples from 36 patients with clinically and serologically confirmed whooping cough disease (pertussis syndrome). Moreover, although the induction of Bsp22 secretion by the laboratory-adapted 18323 strain in the course of mice lung infection was observed, the B. pertussis 18323-infected mice did not mount any detectable serum antibody response against Bsp22. Furthermore, immunization with recombinant Bsp22 protein yielded induction of high Bsp22-specific serum antibody titers but did not protect mice against an intranasal challenge with B. pertussis 18323. Unlike for B. bronchiseptica, hence, the Bsp22 protein is nonimmunogenic, and/or the serum antibody response to it is suppressed, during B. pertussis infections of humans and mice. PMID:23690400

  11. New vaccine strategies against enterotoxigenic Escherichia coli: II: Enhanced systemic and secreted antibody responses against the CFA/I fimbriae by priming with DNA and boosting with a live recombinant Salmonella vaccine

    Directory of Open Access Journals (Sweden)

    M.O. Lásaro

    1999-02-01

    Full Text Available The induction of systemic (IgG and mucosal (IgA antibody responses against the colonization factor I antigen (CFA/I of enterotoxigenic Escherichia coli (ETEC was evaluated in mice primed with an intramuscularly delivered CFA/I-encoding DNA vaccine followed by two oral immunizations with a live recombinant Salmonella typhimurium vaccine strain expressing the ETEC antigen. The booster effect induced by the oral immunization was detected two weeks and one year after the administration of the DNA vaccine. The DNA-primed/Salmonella-boosted vaccination regime showed a synergistic effect on the induced CFA/I-specific systemic and secreted antibody levels which could not be attained by either immunization strategy alone. These results suggest that the combined use of DNA vaccines and recombinant Salmonella vaccine strains can be a useful immunization strategy against enteric pathogens.

  12. Affinity of antibody secreted by a single cell

    International Nuclear Information System (INIS)

    Doran, D.M.

    1978-01-01

    It was the intention of this research to measure the affinity of antibody secreted by a single cell, and to describe the spectrum of affinities displayed in response to antigenic stimulation. The single cell secreting specific antibody was isolated by means of the hemolytic plaque assay. The amount of antibody secreted by the cell was to be measured through the use of a solid phase radioimmunoassay. The affinity of the antibody would be estimated by comparing the diameter of the plaque, and the amount of antibody secreted, with a mathematical theory of the formation of a plaque in agar. As a test system, a solid phase radioimmunoassay was developed for human serum albumin using antibody coupled to Sephadex. A sensitivity of 1 nanogram was attained with this assay. A solid phase radioimmunoassay for mouse immunoglobulin M was developed, using antibody coupled to Sepharose. The sensitivity attained with this assay was only on the order of 10 micrograms. The mouse immunoglobulin M radioimmunoassay was not sensitive enough to measure the amount of antibody secreted by a single cell. From a theoretical equation, the relationship between antibody affinity, plaque diameter and antibody secretion rate was calculated for the experimental conditions used in this research. By assuming a constant antibody secretion rate, an effective binding constant for the antibody was estimated from the average plaque diameters. This effective binding constant was observed to increase during the immune response

  13. A Finite Equivalence of Verifiable Multi-secret Sharing

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2012-02-01

    Full Text Available We give an abstraction of verifiable multi-secret sharing schemes that is accessible to a fully mechanized analysis. This abstraction is formalized within the applied pi-calculus by using an equational theory which characterizes the cryptographic semantics of secret share. We also present an encoding from the equational theory into a convergent rewriting system, which is suitable for the automated protocol verifier ProVerif. Based on that, we verify the threshold certificate protocol in ProVerif.

  14. Discovery of the type VII ESX-1 secretion needle?

    Science.gov (United States)

    Ates, Louis S; Brosch, Roland

    2017-01-01

    Mycobacterium tuberculosis, the etiological agent of human tuberculosis, harbours five ESAT-6/type VII secretion (ESX/T7S) systems. The first esx gene clusters were identified during the genome-sequencing project of M. tuberculosis H37Rv. Follow-up studies revealed additional genes playing important roles in ESX/T7S systems. Among the latter genes, one can find those that encode Pro-Glu (PE) and Pro-Pro-Glu (PPE) proteins as well as a gene cluster that is encoded >260 kb upstream of the esx-1 locus and encodes ESX-1 secretion-associated proteins EspA (Rv3616c), EspC (Rv3615c) and EspD (Rv3614c). The espACD cluster has been suggested to have an important function in ESX-1 secretion since EspA-EspC and EsxA-EsxB are mutually co-dependent on each other for secretion. However, the molecular mechanism of this co-dependence and interaction between the substrates remained unknown. In this issue of Molecular Microbiology, Lou and colleagues show that EspC forms high-molecular weight polymerization complexes that resemble selected components of type II, III and/or IV secretion systems of Gram-negative bacteria. Indeed, EspC-multimeric complexes form filamentous structures that could well represent a secretion needle of ESX-1 type VII secretion systems. This exciting observation opens new avenues for research to discover and characterize ESX/T7S components and elucidates the co-dependence of EsxA/B secretion with EspA/C. © 2016 John Wiley & Sons Ltd.

  15. On alternative approach for verifiable secret sharing

    OpenAIRE

    Kulesza, Kamil; Kotulski, Zbigniew; Pieprzyk, Joseph

    2002-01-01

    Secret sharing allows split/distributed control over the secret (e.g. master key). Verifiable secret sharing (VSS) is the secret sharing extended by verification capacity. Usually verification comes at the price. We propose "free lunch", the approach that allows to overcome this inconvenience.

  16. Quantum strongly secure ramp secret sharing

    DEFF Research Database (Denmark)

    Zhang, Paul; Matsumoto, Rytaro Yamashita

    2015-01-01

    Quantum secret sharing is a scheme for encoding a quantum state (the secret) into multiple shares and distributing them among several participants. If a sufficient number of shares are put together, then the secret can be fully reconstructed. If an insufficient number of shares are put together...... however, no information about the secret can be revealed. In quantum ramp secret sharing, partial information about the secret is allowed to leak to a set of participants, called an unqualified set, that cannot fully reconstruct the secret. By allowing this, the size of a share can be drastically reduced....... This paper introduces a quantum analog of classical strong security in ramp secret sharing schemes. While the ramp secret sharing scheme still leaks partial information about the secret to unqualified sets of participants, the strong security condition ensures that qudits with critical information can...

  17. A trade secret model for genomic biobanking.

    Science.gov (United States)

    Conley, John M; Mitchell, Robert; Cadigan, R Jean; Davis, Arlene M; Dobson, Allison W; Gladden, Ryan Q

    2012-01-01

    Genomic biobanks present ethical challenges that are qualitatively unique and quantitatively unprecedented. Many critics have questioned whether the current system of informed consent can be meaningfully applied to genomic biobanking. Proposals for reform have come from many directions, but have tended to involve incremental change in current informed consent practice. This paper reports on our efforts to seek new ideas and approaches from those whom informed consent is designed to protect: research subjects. Our model emerged from semi-structured interviews with healthy volunteers who had been recruited to join either of two biobanks (some joined, some did not), and whom we encouraged to explain their concerns and how they understood the relationship between specimen contributors and biobanks. These subjects spoke about their DNA and the information it contains in ways that were strikingly evocative of the legal concept of the trade secret. They then described the terms and conditions under which they might let others study their DNA, and there was a compelling analogy to the commonplace practice of trade secret licensing. We propose a novel biobanking model based on this trade secret concept, and argue that it would be a practical, legal, and ethical improvement on the status quo. © 2012 American Society of Law, Medicine & Ethics, Inc.

  18. Catechin secretion and phytotoxicity: Fact not fiction.

    Science.gov (United States)

    Bais, Harsh P; Kaushik, Shail

    2010-09-01

    Research indicates that the invasiveness of Centaurea stoebe is attributed to the stronger allelopathic effects on the native North American species than on the related European species, which is one of the unquestionable aspects of the "novel weapons hypothesis (NWH)." Studies originating from controlled to field conditions have shown that C. stoebe utilizes its biochemical potential to exert its invasiveness. The roots of C. stoebe secrete a potent phytotoxin, catechin, which has a detrimental effect on the surrounding plant species. Although, studies on catechin secretion and phytotoxicity represent one of the most well studied systems describing negative plant-plant interactions, it has also sparked controversies lately due to its phytotoxicity dosages and secretion effluxes. Previous reports negate the phytotoxic and pro-oxidant nature of catechin.1-3 In our recent study we have shown that catechin is highly phytotoxic against Arabidopsis thaliana and Festuca idahoensis. We also show that (±) catechin applied to roots of A. thaliana induces reactive oxygen species (ROS) confirming the pro-oxidant nature of catechin. In addition, activation of signature cell death genes such as acd2 and cad1 post catechin treatment in A. thaliana ascertains the phytotoxic nature of catechin.

  19. Intermittent subglottic secretion drainage may cause tracheal damage in patients with few oropharyngeal secretions.

    Science.gov (United States)

    Suys, E; Nieboer, K; Stiers, W; De Regt, J; Huyghens, L; Spapen, H

    2013-12-01

    Injurious prolapse of tracheal mucosa into the suction port has been reported in up to 50% of intubated patients receiving continuous aspiration of subglottic secretions. We investigated whether similar injury could be inflicted by automated intermittent aspiration. Six consecutive patients, intubated with the Mallinckrodt TaperGuard Evac™ endotracheal tube, were studied. A flow sensor was placed between the vacuum regulating system and the mucus collector. Intermittent suctioning was performed at a pressure of -125 mmHg with a 25s interval and duration of 15s. After 24h, a CT scan of the tracheal region was performed. Excessive negative suction pressure, a fast drop in aspiration flow to zero, and important "swinging" movements of secretions in the evacuation line were observed in all patients. Oral instillation of antiseptic mouthwash restored normal aspiration flow and secretion mobility. CT imaging showed marked entrapment of tracheal mucosa into the suction port in all patients. In patients with few oropharyngeal secretions, automated intermittent subglottic aspiration may result in significant and potential harmful invagination of tracheal mucosa into the suction lumen. A critical amount of fluid must be present in the oropharynx to assure adequate and safe aspiration. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Multi-group dynamic quantum secret sharing with single photons

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongwei [School of Science and State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Ma, Haiqiang, E-mail: hqma@bupt.edu.cn [School of Science and State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Wei, Kejin [School of Science and State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Yang, Xiuqing [School of Science, Beijing Jiaotong University, Beijing 100044 (China); Qu, Wenxiu; Dou, Tianqi; Chen, Yitian; Li, Ruixue; Zhu, Wu [School of Science and State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2016-07-15

    In this letter, we propose a novel scheme for the realization of single-photon dynamic quantum secret sharing between a boss and three dynamic agent groups. In our system, the boss can not only choose one of these three groups to share the secret with, but also can share two sets of independent keys with two groups without redistribution. Furthermore, the security of communication is enhanced by using a control mode. Compared with previous schemes, our scheme is more flexible and will contribute to a practical application. - Highlights: • A multi-group dynamic quantum secret sharing with single photons scheme is proposed. • Any one of the groups can be chosen to share secret through controlling the polarization of photons. • Two sets of keys can be shared simultaneously without redistribution.

  1. Impaired Follistatin Secretion in Cirrhosis

    DEFF Research Database (Denmark)

    Rinnov, Anders Rasmussen; Plomgaard, Peter; Pedersen, Bente Klarlund

    2016-01-01

    compared to healthy control participants. DESIGN, SETTING, AND PARTICIPANTS: To experimentally increase the glucagon-insulin ratio (mimicking the hormonal effect of exercise), we infused glucagon/somatostatin (to inhibit insulin secretion) and compared the acute follistatin increase in eight male cirrhosis...... controls (27.6 ± 3.8 vs 34.5 ± 2.9%, respectively; P = .001). CONCLUSIONS: Patients with cirrhosis show impaired capacity to acutely secrete follistatin. The decrease in acute follistatin release may contribute to the loss of muscle mass in liver cirrhosis....

  2. Secrets and Disclosures: How Young Children Handle Secrets

    Science.gov (United States)

    Anagnostaki, Lida; Wright, Michael J.; Papathanasiou, Athanasia

    2013-01-01

    The authors examined the influence of content and verbal cues on young children's understanding of secret information and of its disclosure. Participants were 209 5- and 6-year-old children in an experiment where a puppet, named Zinc, was the protagonist. Children were asked to whom Zinc would disclose a list of pieces of information, some of…

  3. New players in the same old game: a system level in silico study to predict type III secretion system and effector proteins in bacterial genomes reveals common themes in T3SS mediated pathogenesis.

    Science.gov (United States)

    Sadarangani, Vineet; Datta, Sunando; Arunachalam, Manonmani

    2013-07-26

    Type III secretion system (T3SS) plays an important role in virulence or symbiosis of many pathogenic or symbiotic bacteria [CHM 2:291-294, 2007; Physiology (Bethesda) 20:326-339, 2005]. T3SS acts like a tunnel between a bacterium and its host through which the bacterium injects 'effector' proteins into the latter [Nature 444:567-573, 2006; COSB 18:258-266, 2008]. The effectors spatially and temporally modify the host signalling pathways [FEMS Microbiol Rev 35:1100-1125, 2011; Cell Host Microbe5:571-579, 2009]. In spite its crucial role in host-pathogen interaction, the study of T3SS and the associated effectors has been limited to a few bacteria [Cell Microbiol 13:1858-1869, 2011; Nat Rev Microbiol 6:11-16, 2008; Mol Microbiol 80:1420-1438, 2011]. Before one set out to perform systematic experimental studies on an unknown set of bacteria it would be beneficial to identify the potential candidates by developing an in silico screening algorithm. A system level study would also be advantageous over traditional laboratory methods to extract an overriding theme for host-pathogen interaction, if any, from the vast resources of data generated by sequencing multiple bacterial genomes. We have developed an in silico protocol in which the most conserved set of T3SS proteins was used as the query against the entire bacterial database with increasingly stringent search parameters. It enabled us to identify several uncharacterized T3SS positive bacteria. We adopted a similar strategy to predict the presence of the already known effectors in the newly identified T3SS positive bacteria. The huge resources of biochemical data [FEMS Microbiol Rev 35:1100-1125, 2011; Cell Host Microbe 5:571-579, 2009; BMC Bioinformatics 7(11):S4, 2010] on the T3SS effectors enabled us to search for the common theme in T3SS mediated pathogenesis. We identified few cellular signalling networks in the host, which are manipulated by most of the T3SS containing pathogens. We went on to look for

  4. Raspberry Pi for secret agents

    CERN Document Server

    Sjogelid, Stefan

    2015-01-01

    This book is an easy-to-follow guide with practical examples in each chapter. Suitable for the novice and expert alike, each topic provides a fast and easy way to get started with exciting applications and also guides you through setting up the Raspberry Pi as a secret agent toolbox.

  5. Unraveling the Wnt secretion pathway

    NARCIS (Netherlands)

    Harterink, M.

    2011-01-01

    The Wnt family of signaling proteins has essential functions in development and adult tissue homeostasis throughout the animal kingdom. Although signaling cascades triggered by Wnt proteins have been extensively studied, much remains to be learned about how Wnts are produced and secreted and how

  6. VIP secreting tumours in infancy

    International Nuclear Information System (INIS)

    Davies, R.P.; Slavotinek, J.P.; Dorney, S.F.A.

    1990-01-01

    Vasoactive intestinal polypeptide (VIP) secreting neural crest tumours are an uncommon but important treatable cause of intractable childhood diarrhoea. The radiological appearances of two cases are presented with a review of radiological findings in childhood VIP secreting neural crest tumours. Twenty eight cases of childhood VIP secreting neural crest tumours were reviewed. Nineteen (68%) were ganglioneuroblastomas and nine (32%) were ganglioneuromas. The majority of tumours (66%) were in a paravertebral location in the abdomen indicating that a search for such a tumour should be initiated at this site. Eighteen of the twenty eight cases reviewed discussed relevant radiological investigations. Calcification was detected in 50% of abdominal radiographs. Gut dilatation was often a prominent feature. A mass was detected in 5 of 5 cases where ultrasound findings were reported, and seven of seven cases with CT findings reported. Prior to the availability of CT and ultrasound the most useful investigation was IVU which demonstrated evidence of a mass in 5 of 9 cases. The presence of paravertebral calcification and gut dilatation on the plain radiograph of a child with intractable diarrhoea suggests the presence of a VIP secreting neural crest tumour. If an abdominal tumour is not found in the appropriate clinical setting and VIP levels are elevated, a widespread search of the paravertebral region is indicated. (orig.)

  7. Competition of organic anions for furosemide and p-aminohippurate secretion in the rabbit

    International Nuclear Information System (INIS)

    Bidiville, J.; Roch-Ramel, F.

    1986-01-01

    The excretion of [ 14 C]- or [ 35 S]furosemide and [ 3 H]-p-aminohippurate (PAH) injected within 4 min into the left renal artery of rabbits was measured under brisk mannitol diuresis. The estimated rate of furosemide secretion during the first pass through the left kidney was lower than that of PAH when neither of the two transport processes were saturated: 7.9 and 12.9% of the total amounts injected were secreted per minute, respectively. Different competitive inhibitors were injected i.v. Probenecid (50 mg/kg) inhibited furosemide and PAH secretion by 95 and 80%, respectively. Pyrazinoate at plasma concentrations of 3 to 5 mM had no effect on either anion. Indomethacin (10 mg/kg) depressed furosemide secretion by 24% but had no effect on PAH secretion. PAH at a concentration of 9 to 17 mM in plasma depressed furosemide secretion by only 44 to 66%. Furosemide did not inhibit PAH secretion when infused into the left renal artery at a rate 5000 times higher than PAH. It was concluded that furosemide is secreted partly by the transport system secreting PAH, for which it had only a low affinity, and partly by a transport system for which indomethacin had some affinity. This latter transport system, in turn, differs from that secreting pyrazinoate. The furosemide-induced natriuresis, in both kidneys, was proportional to the urinary excretion rate of furosemide until the fractional excretion of Na+ reached an apparent maximum of 20 to 30%

  8. Comparative genomics of the type VI secretion systems of Pantoea and Erwinia species reveals the presence of putative effector islands that may be translocated by the VgrG and Hcp proteins

    Directory of Open Access Journals (Sweden)

    De Maayer Pieter

    2011-11-01

    Full Text Available Abstract Background The Type VI secretion apparatus is assembled by a conserved set of proteins encoded within a distinct locus. The putative effector proteins Hcp and VgrG are also encoded within these loci. We have identified numerous distinct Type VI secretion system (T6SS loci in the genomes of several ecologically diverse Pantoea and Erwinia species and detected the presence of putative effector islands associated with the hcp and vgrG genes. Results Between two and four T6SS loci occur among the Pantoea and Erwinia species. While two of the loci (T6SS-1 and T6SS-2 are well conserved among the various strains, the third (T6SS-3 locus is not universally distributed. Additional orthologous loci are present in Pantoea sp. aB-valens and Erwinia billingiae Eb661. Comparative analysis of the T6SS-1 and T6SS-3 loci showed non-conserved islands associated with the vgrG and hcp, and vgrG genes, respectively. These regions had a G+C content far lower than the conserved portions of the loci. Many of the proteins encoded within the hcp and vgrG islands carry conserved domains, which suggests they may serve as effector proteins for the T6SS. A number of the proteins also show homology to the C-terminal extensions of evolved VgrG proteins. Conclusions Extensive diversity was observed in the number and content of the T6SS loci among the Pantoea and Erwinia species. Genomic islands could be observed within some of T6SS loci, which are associated with the hcp and vgrG proteins and carry putative effector domain proteins. We propose new hypotheses concerning a role for these islands in the acquisition of T6SS effectors and the development of novel evolved VgrG and Hcp proteins.

  9. Characterization of Pseudomonas aeruginosa chitinase, a gradually secreted protein.

    Science.gov (United States)

    Folders, J; Algra, J; Roelofs, M S; van Loon, L C; Tommassen, J; Bitter, W

    2001-12-01

    The gram-negative bacterium Pseudomonas aeruginosa secretes many proteins into its extracellular environment via the type I, II, and III secretion systems. In this study, a gene, chiC, coding for an extracellular chitinolytic enzyme, was identified. The chiC gene encodes a polypeptide of 483 amino acid residues, without a typical N-terminal signal sequence. Nevertheless, an N-terminal segment of 11 residues was found to be cleaved off in the secreted protein. The protein shows sequence similarity to the secreted chitinases ChiC of Serratia marcescens, ChiA of Vibrio harveyi, and ChiD of Bacillus circulans and consists of an activity domain and a chitin-binding domain, which are separated by a fibronectin type III domain. ChiC was able to bind and degrade colloidal chitin and was active on the artificial substrates carboxymethyl-chitin-Remazol Brilliant Violet and p-nitrophenyl-beta-D-N,N',N"-triacetylchitotriose, but not on p-nitrophenyl-beta-D-N-acetylglucosamine, indicating that it is an endochitinase. Expression of the chiC gene appears to be regulated by the quorum-sensing system of P. aeruginosa, since this gene was not expressed in a lasIR vsmI mutant. After overnight growth, the majority of the ChiC produced was found intracellularly, whereas only small amounts were detected in the culture medium. However, after several days, the cellular pool of ChiC was largely depleted, and the protein was found in the culture medium. This release could not be ascribed to cell lysis. Since ChiC did not appear to be secreted via any of the known secretion systems, a novel secretion pathway seems to be involved.

  10. Tamper-proof secret image-sharing scheme for identifying cheated secret keys and shared images

    Science.gov (United States)

    Chen, Chien-Chang; Liu, Chong-An

    2013-01-01

    A (t,n) secret image-sharing scheme shares a secret image to n participants, and the t users recover the image. During the recovery procedure of a conventional secret image-sharing scheme, cheaters may use counterfeit secret keys or modified shared images to cheat other users' secret keys and shared images. A cheated secret key or shared image leads to an incorrect secret image. Unfortunately, the cheater cannot be identified. We present an exponent and modulus-based scheme to provide a tamper-proof secret image-sharing scheme for identifying cheaters on secret keys or shared images. The proposed scheme allows users to securely select their secret key. This assignment can be performed over networks. Modulus results of each shared image is calculated to recognize cheaters of a shared image. Experimental results indicate that the proposed scheme is excellent at identifying cheated secret keys and shared images.

  11. 76 FR 66937 - Privacy Act of 1974; Department of Homeland Security/United States Secret Service-003 Non...

    Science.gov (United States)

    2011-10-28

    ... 1974; Department of Homeland Security/United States Secret Service--003 Non-Criminal Investigation... Security/United States Secret Service--003 Non-Criminal Investigation Information System.'' As a result of... Secret Service, 245 Murray Lane SW., Building T-5, Washington, DC 20223. For privacy issues please...

  12. Secretion and activation of the Serratia marcescens hemolysin by structurally defined ShlB mutants.

    Science.gov (United States)

    Pramanik, Avijit; Könninger, Ulrich; Selvam, Arun; Braun, Volkmar

    2014-05-01

    The ShlA hemolysin of Serratia marcescens is secreted across the outer membrane by the ShlB protein; ShlB belongs to the two-partner secretion system (type Vb), a subfamily of the Omp85 outer membrane protein assembly and secretion superfamily. During secretion, ShlA is converted from an inactive non-hemolytic form into an active hemolytic form. The structure of ShlB is predicted to consist of the N-terminal α-helix H1, followed by the two polypeptide-transport-associated domains POTRA P1 and P2, and the β-barrel of 16 β-strands. H1 is inserted into the pore of the β-barrel in the outer membrane; P1 and P2 are located in the periplasm. To obtain insights into the secretion and activation of ShlA by ShlB, we isolated ShlB mutants impaired in secretion and/or activation. The triple H1 P1 P2 mutant did not secrete ShlA. The P1 and P2 deletion derivatives secreted reduced amounts of ShlA, of which P1 showed some hemolysis, whereas P2 was inactive. Deletion of loop 6 (L6), which is conserved among exporters of the Omp85 family, compromised activation but retained low secretion. Secretion-negative mutants generated by random mutagenesis were located in loop 6. The inactive secreted ShlA derivatives were complemented in vitro to active ShlA by an N-terminal ShlA fragment (ShlA242) secreted by ShlB. Deletion of H1 did not impair secretion of hemolytic ShlA. The study defines domains of ShlB which are important for ShlA secretion and activation. Copyright © 2013 Elsevier GmbH. All rights reserved.

  13. 29 CFR 1903.9 - Trade secrets.

    Science.gov (United States)

    2010-07-01

    ... INSPECTIONS, CITATIONS AND PROPOSED PENALTIES § 1903.9 Trade secrets. (a) Section 15 of the Act provides: “All... concerns or relates to the trade secrets, processes, operations, style of work, or apparatus, or to the...

  14. Pituitary-hormone secretion by thyrotropinomas

    NARCIS (Netherlands)

    Roelfsema, Ferdinand; Kok, Simon; Kok, Petra; Pereira, Alberto M.; Biermasz, Nienke R.; Smit, Jan W.; Frolich, Marijke; Keenan, Daniel M.; Veldhuis, Johannes D.; Romijn, Johannes A.

    2009-01-01

    Hormone secretion by somatotropinomas, corticotropinomas and prolactinomas exhibits increased pulse frequency, basal and pulsatile secretion, accompanied by greater disorderliness. Increased concentrations of growth hormone (GH) or prolactin (PRL) are observed in about 30% of thyrotropinomas leading

  15. Pancreatic bicarbonate secretion involves two proton pumps

    DEFF Research Database (Denmark)

    Novak, Ivana; Wang, Jing; Henriksen, Katrine L.

    2011-01-01

    Pancreas secretes fluid rich in digestive enzymes and bicarbonate. The alkaline secretion is important in buffering of acid chyme entering duodenum and for activation of enzymes. This secretion is formed in pancreatic ducts, and studies to date show that plasma membranes of duct epithelium expres...

  16. 5 CFR 2421.15 - Secret ballot.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Secret ballot. 2421.15 Section 2421.15... FEDERAL LABOR RELATIONS AUTHORITY MEANING OF TERMS AS USED IN THIS SUBCHAPTER § 2421.15 Secret ballot. Secret ballot means the expression by ballot, voting machine or otherwise, but in no event by proxy, of a...

  17. 29 CFR 452.97 - Secret ballot.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 2 2010-07-01 2010-07-01 false Secret ballot. 452.97 Section 452.97 Labor Regulations... OF 1959 Election Procedures; Rights of Members § 452.97 Secret ballot. (a) A prime requisite of elections regulated by title IV is that they be held by secret ballot among the members or in appropriate...

  18. 29 CFR 401.11 - Secret ballot.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 2 2010-07-01 2010-07-01 false Secret ballot. 401.11 Section 401.11 Labor Regulations Relating to Labor OFFICE OF LABOR-MANAGEMENT STANDARDS, DEPARTMENT OF LABOR LABOR-MANAGEMENT STANDARDS MEANING OF TERMS USED IN THIS SUBCHAPTER § 401.11 Secret ballot. Secret ballot means the expression by...

  19. 22 CFR 1421.15 - Secret ballot.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Secret ballot. 1421.15 Section 1421.15 Foreign Relations FOREIGN SERVICE LABOR RELATIONS BOARD; FEDERAL LABOR RELATIONS AUTHORITY; GENERAL COUNSEL OF THE... THIS SUBCHAPTER § 1421.15 Secret ballot. Secret ballot means the expression by ballot, voting machine...

  20. 29 CFR 1202.4 - Secret ballot.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Secret ballot. 1202.4 Section 1202.4 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.4 Secret ballot. In conducting such investigation, the Board is authorized to take a secret ballot of the employees involved, or...

  1. Some Economics of Trade Secret Law

    OpenAIRE

    David D. Friedman; William M. Landes; Richard A. Posner

    1991-01-01

    Despite the practical importance of trade secrets to the business community, the law of trade secrets is a neglected orphan in economic analysis. This paper sketches an approach to the economics of trade secret law that connects it more closely both to other areas of intellectual property and to broader issues in the positive economic theory of the common law.

  2. Weegee’s City Secrets

    OpenAIRE

    TRACHTENBERG, Alan

    2011-01-01

    En tant que photographe indépendant de meurtres, d’accidents, d’incendies, mais aussi de moments de loisirs dans la ville — de scènes de violence et de plaisir — Weegee travaillait essentiellement la nuit et utilisait un flash puissant associé à son appareil-photo de presse. Ses « secrets pour réaliser des photographies avec un flash » consistent à donner des conseils pratiques et techniques pour débutants. Mais au cœur de la rhétorique de ses « secrets » se trouvent des réflexions subtiles e...

  3. The Smart Grid - A saucerful of secrets?

    International Nuclear Information System (INIS)

    Wissner, Matthias

    2011-01-01

    To many, a lot of secrets are at the bottom of the often-cited catchphrase 'Smart Grid'. This article gives an overview of the options that information and communication technology (ICT) offers for the restructuring and modernisation of the German power system, in particular with a view towards its development into a Smart Grid and thus tries to reveal these secrets. After a short outline on the development of ICT in terms of technology types and their availability, the further analysis highlights upcoming challenges in all parts of the power value chain and possible solutions for these challenges through the intensified usage of ICT applications. They are examined with regard to their effectiveness and efficiency in the fields of generation, transmission, distribution and supply. Finally, potential obstacles that may defer the introduction of ICT into the power system are shown. The analysis suggests that if certain hurdles are taken, the huge potential of ICT can create additional value in various fields of the whole power value chain. This ranges from increased energy efficiency and the more sophisticated integration of decentralised (renewable) energy plants to a higher security of supply and more efficient organisation of market processes. The results are true for the German power market but can in many areas also be transferred to other industrialised nations with liberalised power markets.

  4. The Role of the Pituitary-Adrenocortical Axis System in the Regulation of Secretion of Digestive Glands of Wrestlers during Sports and Postsports Ontogenesis

    Science.gov (United States)

    Panov, Sergei F.; Panova, Irina P.; Volunskaya, Elena V.; Chebotarev, Andrei V.

    2016-01-01

    According to many researchers its necessary to research a hormonal profile in order to determine mechanisms of regulation of functions of the digestive conveyor during sports activities. In the paper the results of the carried out research on studying of a role of pituitary-adrenocortical axis system of adaptive reactions in activities of the…

  5. Bottleneck in secretion of α-amylase in Bacillus subtilis.

    Science.gov (United States)

    Yan, Shaomin; Wu, Guang

    2017-07-19

    Amylase plays an important role in biotechnology industries, and Gram-positive bacterium Bacillus subtilis is a major host to produce heterogeneous α-amylases. However, the secretion stress limits the high yield of α-amylase in B. subtilis although huge efforts have been made to address this secretion bottleneck. In this question-oriented review, every effort is made to answer the following questions, which look simple but are long-standing, through reviewing of literature: (1) Does α-amylase need a specific and dedicated chaperone? (2) What signal sequence does CsaA recognize? (3) Does CsaA require ATP for its operation? (4) Does an unfolded α-amylase is less soluble than a folded one? (5) Does α-amylase aggregate before transporting through Sec secretion system? (6) Is α-amylase sufficient stable to prevent itself from misfolding? (7) Does α-amylase need more disulfide bonds to be stabilized? (8) Which secretion system does PrsA pass through? (9) Is PrsA ATP-dependent? (10) Is PrsA reused after folding of α-amylase? (11) What is the fate of PrsA? (12) Is trigger factor (TF) ATP-dependent? The literature review suggests that not only the most of those questions are still open to answers but also it is necessary to calculate ATP budget in order to better understand how B. subtilis uses its energy for production and secretion.

  6. Regulation of ghrelin secretion and action.

    Science.gov (United States)

    Camiña, Jesus P; Carreira, Marcos C; Micic, Dragan; Pombo, Manuel; Kelestimur, Fahrettin; Dieguez, Carlos; Casanueva, Felipe F

    2003-10-01

    (store-operated calcium channels). Upon repeated administration, ghrelin showed a marked suppression of ghrelin-mediated elevations of intracellular calcium. This homologous desensitization represents an important physiological mechanism that modulates receptor responsiveness and acts as an information filter for intracellular signaling system. The discovery of ghrelin adds a new component to the complex machinery responsible for regulation of GH secretion in connection with the regulation of appetite and energy homeostasis.

  7. Semiquantum secret sharing using entangled states

    International Nuclear Information System (INIS)

    Li Qin; Chan, W. H.; Long Dongyang

    2010-01-01

    Secret sharing is a procedure for sharing a secret among a number of participants such that only the qualified subsets of participants have the ability to reconstruct the secret. Even in the presence of eavesdropping, secret sharing can be achieved when all the members are quantum. So what happens if not all the members are quantum? In this paper, we propose two semiquantum secret sharing protocols by using maximally entangled Greenberger-Horne-Zeilinger-type states in which quantum Alice shares a secret with two classical parties, Bob and Charlie, in a way that both parties are sufficient to obtain the secret, but one of them cannot. The presented protocols are also shown to be secure against eavesdropping.

  8. LcrG secretion is not required for blocking of Yops secretion in Yersinia pestis

    Directory of Open Access Journals (Sweden)

    Matson Jyl S

    2008-02-01

    Full Text Available Abstract Background LcrG, a negative regulator of the Yersinia type III secretion apparatus has been shown to be primarily a cytoplasmic protein, but is secreted at least in Y. pestis. LcrG secretion has not been functionally analyzed and the relevance of LcrG secretion on LcrG function is unknown. Results An LcrG-GAL4AD chimera, originally constructed for two-hybrid analyses to analyze LcrG protein interactions, appeared to be not secreted but the LcrG-GAL4AD chimera retained the ability to regulate Yops secretion. This result led to further investigation to determine the significance of LcrG secretion on LcrG function. Additional analyses including deletion and substitution mutations of amino acids 2–6 in the N-terminus of LcrG were constructed to analyze LcrG secretion and LcrG's ability to control secretion. Some changes to the N-terminus of LcrG were found to not affect LcrG's secretion or LcrG's secretion-controlling activity. However, substitution of poly-isoleucine in the N-terminus of LcrG did eliminate LcrG secretion but did not affect LcrG's secretion controlling activity. Conclusion These results indicate that secretion of LcrG, while observable and T3SS mediated, is not relevant for LcrG's ability to control secretion.

  9. Production, secretion, and stability of human secreted alkaline phosphatase in tobacco NT1 cell suspension cultures.

    Science.gov (United States)

    Becerra-Arteaga, Alejandro; Mason, Hugh S; Shuler, Michael L

    2006-01-01

    Tobacco NT1 cell suspension cultures secreting active human secreted alkaline phosphatase (SEAP) were generated for the first time as a model system to study recombinant protein production, secretion, and stability in plant cell cultures. The SEAP gene encodes a secreted form of the human placental alkaline phosphatase (PLAP). During batch culture, the highest level of active SEAP in the culture medium (0.4 U/mL, corresponding to approximately 27 mg/L) was observed at the end of the exponential growth phase. Although the level of active SEAP decreased during the stationary phase, the activity loss did not appear to be due to SEAP degradation (based on Western blots) but due to SEAP denaturation. The protein-stabilizing agents polyvinylpirrolidone (PVP) and bacitracin were added extracellularly to test for their ability to reduce the loss of SEAP activity during the stationary phase. Bacitracin (100 mg/L) was the most effective treatment at sustaining activity levels for up to 17 days post-subculture. Commercially available human placental alkaline phosphatase (PLAP) was used to probe the mechanism of SEAP deactivation. Experiments with PLAP in sterile and conditioned medium corroborated the denaturation of SEAP by factors generated by cell growth and not due to simple proteolysis. We also show for the first time that the factors promoting activity loss are heat labile at 95 degrees C but not at 70 degrees C, and they are not inactivated after a 5 day incubation period under normal culture conditions (27 degrees C). In addition, there were no significant changes in pH or redox potential when comparing sterile and cell-free conditioned medium during PLAP incubation, indicating that these factors were unimportant.

  10. Myeloma cells suppress osteoblasts through sclerostin secretion

    Energy Technology Data Exchange (ETDEWEB)

    Colucci, S; Brunetti, G; Oranger, A [Department of Human Anatomy and Histology, University of Bari Medical School, Bari (Italy); Mori, G [Department of Biomedical Science, University of Foggia, Foggia (Italy); Sardone, F [Department of Human Anatomy and Histology, University of Bari Medical School, Bari (Italy); Specchia, G; Rinaldi, E; Curci, P; Liso, V [Department of Emergency and Organ Transplantation, Hematology Section, Bari University Medical School, Bari (Italy); Passeri, G [Department of Internal Medicine and Biomedical Sciences, Center for Metabolic Bone Diseases, University of Parma, Parma (Italy); Zallone, A [Department of Human Anatomy and Histology, University of Bari Medical School, Bari (Italy); Rizzi, R [Department of Emergency and Organ Transplantation, Hematology Section, Bari University Medical School, Bari (Italy); Grano, M [Department of Human Anatomy and Histology, University of Bari Medical School, Bari (Italy)

    2011-06-01

    Wingless-type (Wnt) signaling through the secretion of Wnt inhibitors Dickkopf1, soluble frizzled-related protein-2 and -3 has a key role in the decreased osteoblast (OB) activity associated with multiple myeloma (MM) bone disease. We provide evidence that another Wnt antagonist, sclerostin, an osteocyte-expressed negative regulator of bone formation, is expressed by myeloma cells, that is, human myeloma cell lines (HMCLs) and plasma cells (CD138+ cells) obtained from the bone marrow (BM) of a large number of MM patients with bone disease. We demonstrated that BM stromal cells (BMSCs), differentiated into OBs and co-cultured with HMCLs showed, compared with BMSCs alone, reduced expression of major osteoblastic-specific proteins, decreased mineralized nodule formation and attenuated the expression of members of the activator protein 1 transcription factor family (Fra-1, Fra-2 and Jun-D). Moreover, in the same co-culture system, the addition of neutralizing anti-sclerostin antibodies restored OB functions by inducing nuclear accumulation of β-catenin. We further demonstrated that the upregulation of receptor activator of nuclear factor κ-B ligand and the downregulation of osteoprotegerin in OBs were also sclerostin mediated. Our data indicated that sclerostin secretion by myeloma cells contribute to the suppression of bone formation in the osteolytic bone disease associated to MM.

  11. Secrets Pages in DR’s Playbook

    DEFF Research Database (Denmark)

    Nielsen, Jakob Isak

    According to former Head of Drama at DR, Ingolf Gabold, one of the “great” and “strange” secrets subtending the success of DR’s TV series is the extremely deliberate work with audiovisual style (Gabold in Nielsen 2012). Here - as elsewhere - Gabold highlights the so-called “paramount-meeting” and......According to former Head of Drama at DR, Ingolf Gabold, one of the “great” and “strange” secrets subtending the success of DR’s TV series is the extremely deliberate work with audiovisual style (Gabold in Nielsen 2012). Here - as elsewhere - Gabold highlights the so-called “paramount...... shifts already took place with Een gang strømer (1987) (Refn in Nielsen 2006). Combining various methods (audiovisual analysis, media systemic analysis [see Hallin & Mancini, Vestergaard 2007] and interview-driven production studies [see Frandsen 2007, Caldwell 2008] that hone in on this particular...... aspect of DR’s productions by interviewing both management and creative personnel) this paper will discuss the causal mechanisms that subtend the development of audiovisual style in DR series from Gøngehøvdingen to 1864 and will conclude with reflections on the role of DR-series’ style in the age...

  12. Loose excitation-secretion coupling in astrocytes.

    Science.gov (United States)

    Vardjan, Nina; Parpura, Vladimir; Zorec, Robert

    2016-05-01

    Astrocytes play an important housekeeping role in the central nervous system. Additionally, as secretory cells, they actively participate in cell-to-cell communication, which can be mediated by membrane-bound vesicles. The gliosignaling molecules stored in these vesicles are discharged into the extracellular space after the vesicle membrane fuses with the plasma membrane. This process is termed exocytosis, regulated by SNARE proteins, and triggered by elevations in cytosolic calcium levels, which are necessary and sufficient for exocytosis in astrocytes. For astrocytic exocytosis, calcium is sourced from the intracellular endoplasmic reticulum store, although its entry from the extracellular space contributes to cytosolic calcium dynamics in astrocytes. Here, we discuss calcium management in astrocytic exocytosis and the properties of the membrane-bound vesicles that store gliosignaling molecules, including the vesicle fusion machinery and kinetics of vesicle content discharge. In astrocytes, the delay between the increase in cytosolic calcium activity and the discharge of secretions from the vesicular lumen is orders of magnitude longer than that in neurons. This relatively loose excitation-secretion coupling is likely tailored to the participation of astrocytes in modulating neural network processing. © 2015 Wiley Periodicals, Inc.

  13. Adrenocorticotropic Hormone Secreting Pheochromocytoma Underlying Glucocorticoid Induced Pheochromocytoma Crisis

    Directory of Open Access Journals (Sweden)

    Gil A. Geva

    2018-01-01

    Full Text Available Context. Pheochromocytomas are hormone secreting tumors of the medulla of the adrenal glands found in 0.1–0.5% of patients with hypertension. The vast majority of pheochromocytomas secrete catecholamines, but they have been occasionally shown to also secrete interleukins, calcitonin, testosterone, and in rare cases adrenocorticotropic hormone. Pheochromocytoma crisis is a life threatening event in which high levels of catecholamines cause a systemic reaction leading to organ failure. Case Description. A 70-year-old man was admitted with acute myocardial ischemia following glucocorticoid administration as part of an endocrine workup for an adrenal mass. Cardiac catheterization disclosed patent coronary arteries and he was discharged. A year later he returned with similar angina-like chest pain. During hospitalization, he suffered additional events of chest pain, shortness of breath, and palpitations following administration of glucocorticoids as preparation for intravenous contrast administration. Throughout his admission, the patient demonstrated both signs of Cushing’s syndrome and high catecholamine levels. Following stabilization of vital parameters and serum electrolytes, the adrenal mass was resected surgically and was found to harbor an adrenocorticotropic hormone secreting pheochromocytoma. This is the first documented case of adrenocorticotropic hormone secreting pheochromocytoma complicated by glucocorticoid induced pheochromocytoma crisis. Conclusion. Care should be taken when administering high doses of glucocorticoids to patients with suspected pheochromocytoma, even in a patient with concomitant Cushing’s syndrome.

  14. Native Small Airways Secrete Bicarbonate

    OpenAIRE

    Shamsuddin, A. K. M.; Quinton, Paul M.

    2014-01-01

    Since the discovery of Cl− impermeability in cystic fibrosis (CF) and the cloning of the responsible channel, CF pathology has been widely attributed to a defect in epithelial Cl− transport. However, loss of bicarbonate (HCO3−) transport also plays a major, possibly more critical role in CF pathogenesis. Even though HCO3− transport is severely affected in the native pancreas, liver, and intestines in CF, we know very little about HCO3− secretion in small airways, the principle site of morbidi...

  15. Secret sharing via quantum entanglement

    International Nuclear Information System (INIS)

    Hillery, M.; Buzek, V.

    1999-01-01

    Secret sharing is a procedure for splitting a message into several parts so that no single part is sufficient to read the message, but the entire set is. This procedure can be implemented using either GHZ states or two-particle entangled states. In the quantum case the presence of an eavesdropper will introduce errors so that her presence can be detected. We also discuss how quantum information can be split into parts so that the message can be reconstructed from a sufficiently large subset of the parts. (Authors)

  16. Weegee’s City Secrets

    Directory of Open Access Journals (Sweden)

    Alan TRACHTENBERG

    2010-03-01

    Full Text Available En tant que photographe indépendant de meurtres, d’accidents, d’incendies, mais aussi de moments de loisirs dans la ville — de scènes de violence et de plaisir — Weegee travaillait essentiellement la nuit et utilisait un flash puissant associé à son appareil-photo de presse. Ses « secrets pour réaliser des photographies avec un flash » consistent à donner des conseils pratiques et techniques pour débutants. Mais au cœur de la rhétorique de ses « secrets » se trouvent des réflexions subtiles et convaincantes révélant la relation entre la lumière et l’obscurité, et plus particulièrement la manière dont la lumière du flash permet de rendre visible l’obscurité. Dans le récit de Weegee, le flash confère à la photographie le pouvoir d’écrire — d’écrire avec la lumière, un mode de représentation singulièrement approprié pour enregistrer des instants de vie dans les rues nocturnes de la ville.As a freelance photographer of crime, accidents, fires, and also of the recreational life of the city—scenes of violence and of pleasure—Weegee worked mainly at night and employed a powerful photoflash attachment to his press camera. His "secrets of shooting with photoflash" consist of practical technical advice for beginners. But within the rhetoric of his "secrets" there lie cogent and subtle reflections on the relation of light to darkness, especially on the way the flash of light makes darkness visible. In Weegee’s account, the photoflash gives photography the power of writing—writing with light, a mode of picturing uniquely suited to recording instants of life on city streets at night.

  17. Quantum secret sharing via local operations and classical communication.

    Science.gov (United States)

    Yang, Ying-Hui; Gao, Fei; Wu, Xia; Qin, Su-Juan; Zuo, Hui-Juan; Wen, Qiao-Yan

    2015-11-20

    We investigate the distinguishability of orthogonal multipartite entangled states in d-qudit system by restricted local operations and classical communication. According to these properties, we propose a standard (2, n)-threshold quantum secret sharing scheme (called LOCC-QSS scheme), which solves the open question in [Rahaman et al., Phys. Rev. A, 91, 022330 (2015)]. On the other hand, we find that all the existing (k, n)-threshold LOCC-QSS schemes are imperfect (or "ramp"), i.e., unauthorized groups can obtain some information about the shared secret. Furthermore, we present a (3, 4)-threshold LOCC-QSS scheme which is close to perfect.

  18. Secretion management in the mechanically ventilated patient.

    Science.gov (United States)

    Branson, Richard D

    2007-10-01

    Secretion management in the mechanically ventilated patient includes routine methods for maintaining mucociliary function, as well as techniques for secretion removal. Humidification, mobilization of the patient, and airway suctioning are all routine procedures for managing secretions in the ventilated patient. Early ambulation of the post-surgical patient and routine turning of the ventilated patient are common secretion-management techniques that have little supporting evidence of efficacy. Humidification is a standard of care and a requisite for secretion management. Both active and passive humidification can be used. The humidifier selected and the level of humidification required depend on the patient's condition and the expected duration of intubation. In patients with thick, copious secretions, heated humidification is superior to a heat and moisture exchanger. Airway suctioning is the most important secretion removal technique. Open-circuit and closed-circuit suctioning have similar efficacy. Instilling saline prior to suctioning, to thin the secretions or stimulate a cough, is not supported by the literature. Adequate humidification and as-needed suctioning are the foundation of secretion management in the mechanically ventilated patient. Intermittent therapy for secretion removal includes techniques either to simulate a cough, to mechanically loosen secretions, or both. Patient positioning for secretion drainage is also widely used. Percussion and postural drainage have been widely employed for mechanically ventilated patients but have not been shown to reduce ventilator-associated pneumonia or atelectasis. Manual hyperinflation and insufflation-exsufflation, which attempt to improve secretion removal by simulating a cough, have been described in mechanically ventilated patients, but neither has been studied sufficiently to support routine use. Continuous lateral rotation with a specialized bed reduces atelectasis in some patients, but has not been shown

  19. Neutrophils are resistant to Yersinia YopJ/P-induced apoptosis and are protected from ROS-mediated cell death by the type III secretion system.

    Directory of Open Access Journals (Sweden)

    Justin L Spinner

    2010-02-01

    Full Text Available The human innate immune system relies on the coordinated activity of macrophages and polymorphonuclear leukocytes (neutrophils or PMNs for defense against bacterial pathogens. Yersinia spp. subvert the innate immune response to cause disease in humans. In particular, the Yersinia outer protein YopJ (Y. pestis and Y. pseudotuberculosis and YopP (Y. enterocolitica rapidly induce apoptosis in murine macrophages and dendritic cells. However, the effects of Yersinia Yop J/P on neutrophil fate are not clearly defined.In this study, we utilized wild-type and mutant strains of Yersinia to test the contribution of YopJ and YopP on induction of apoptosis in human monocyte-derived macrophages (HMDM and neutrophils. Whereas YopJ and YopP similarly induced apoptosis in HMDMs, interaction of human neutrophils with virulence plasmid-containing Yersinia did not result in PMN caspase activation, release of LDH, or loss of membrane integrity greater than PMN controls. In contrast, interaction of human PMNs with the virulence plasmid-deficient Y. pestis strain KIM6 resulted in increased surface exposure of phosphatidylserine (PS and cell death. PMN reactive oxygen species (ROS production was inhibited in a virulence plasmid-dependent but YopJ/YopP-independent manner. Following phagocytic interaction with Y. pestis strain KIM6, inhibition of PMN ROS production with diphenyleneiodonium chloride resulted in a reduction of PMN cell death similar to that induced by the virulence plasmid-containing strain Y. pestis KIM5.Our findings showed that Yersinia YopJ and/or YopP did not induce pronounced apoptosis in human neutrophils. Furthermore, robust PMN ROS production in response to virulence plasmid-deficient Yersinia was associated with increased PMN cell death, suggesting that Yersinia inhibition of PMN ROS production plays a role in evasion of the human innate immune response in part by limiting PMN apoptosis.

  20. Noncoherent capacity of secret-key agreement with public discussion

    KAUST Repository

    Agrawal, Anurag

    2011-09-01

    We study the noncoherent capacity of secret-key agreement with public discussion over independent identically distributed (i.i.d.) Rayleigh fading wireless channels, where neither the sender nor the receivers have access to instantaneous channel state information (CSI). We present two results. At high signal-to-noise ratio (SNR), the secret-key capacity is bounded in SNR, regardless of the number of antennas at each terminal. Second, for a system with a single antenna at both the legitimate and the eavesdropper terminals and an arbitrary number of transmit antennas, the secret-key capacity-achieving input distribution is discrete, with a finite number of mass points. Numerically we observe that at low SNR, the capacity achieving distribution has two mass points with one of them at the origin. © 2011 IEEE.

  1. Noncoherent capacity of secret-key agreement with public discussion

    KAUST Repository

    Agrawal, Anurag; Rezki, Zouheir; Khisti, Ashish J.; Alouini, Mohamed-Slim

    2011-01-01

    We study the noncoherent capacity of secret-key agreement with public discussion over independent identically distributed (i.i.d.) Rayleigh fading wireless channels, where neither the sender nor the receivers have access to instantaneous channel state information (CSI). We present two results. At high signal-to-noise ratio (SNR), the secret-key capacity is bounded in SNR, regardless of the number of antennas at each terminal. Second, for a system with a single antenna at both the legitimate and the eavesdropper terminals and an arbitrary number of transmit antennas, the secret-key capacity-achieving input distribution is discrete, with a finite number of mass points. Numerically we observe that at low SNR, the capacity achieving distribution has two mass points with one of them at the origin. © 2011 IEEE.

  2. Matroids and quantum-secret-sharing schemes

    International Nuclear Information System (INIS)

    Sarvepalli, Pradeep; Raussendorf, Robert

    2010-01-01

    A secret-sharing scheme is a cryptographic protocol to distribute a secret state in an encoded form among a group of players such that only authorized subsets of the players can reconstruct the secret. Classically, efficient secret-sharing schemes have been shown to be induced by matroids. Furthermore, access structures of such schemes can be characterized by an excluded minor relation. No such relations are known for quantum secret-sharing schemes. In this paper we take the first steps toward a matroidal characterization of quantum-secret-sharing schemes. In addition to providing a new perspective on quantum-secret-sharing schemes, this characterization has important benefits. While previous work has shown how to construct quantum-secret-sharing schemes for general access structures, these schemes are not claimed to be efficient. In this context the present results prove to be useful; they enable us to construct efficient quantum-secret-sharing schemes for many general access structures. More precisely, we show that an identically self-dual matroid that is representable over a finite field induces a pure-state quantum-secret-sharing scheme with information rate 1.

  3. A lower isoelectric point increases signal sequence-mediated secretion of recombinant proteins through a bacterial ABC transporter.

    Science.gov (United States)

    Byun, Hyunjong; Park, Jiyeon; Kim, Sun Chang; Ahn, Jung Hoon

    2017-12-01

    Efficient protein production for industrial and academic purposes often involves engineering microorganisms to produce and secrete target proteins into the culture. Pseudomonas fluorescens has a TliDEF ATP-binding cassette transporter, a type I secretion system, which recognizes C-terminal LARD3 signal sequence of thermostable lipase TliA. Many proteins are secreted by TliDEF in vivo when recombined with LARD3, but there are still others that cannot be secreted by TliDEF even when LARD3 is attached. However, the factors that determine whether or not a recombinant protein can be secreted through TliDEF are still unknown. Here, we recombined LARD3 with several proteins and examined their secretion through TliDEF. We found that the proteins secreted via LARD3 are highly negatively charged with highly-acidic isoelectric points (pI) lower than 5.5. Attaching oligo-aspartate to lower the pI of negatively-charged recombinant proteins improved their secretion, and attaching oligo-arginine to negatively-charged proteins blocked their secretion by LARD3. In addition, negatively supercharged green fluorescent protein (GFP) showed improved secretion, whereas positively supercharged GFP did not secrete. These results disclosed that proteins' acidic pI and net negative charge are major factors that determine their secretion through TliDEF. Homology modeling for TliDEF revealed that TliD dimer forms evolutionarily-conserved positively-charged clusters in its pore and substrate entrance site, which also partially explains the pI dependence of the TliDEF-dependent secretions. In conclusion, lowering the isoelectric point improved LARD3-mediated protein secretion, both widening the range of protein targets for efficient production via secretion and signifying an important aspect of ABC transporter-mediated secretions. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Structure of Spa15, a type III secretion chaperone from Shigella flexneri with broad specificity

    NARCIS (Netherlands)

    Eerde, André van; Hamiaux, Cyril; Pérez, Javier; Parsot, Claude; Dijkstra, Bauke W.

    2004-01-01

    Type III secretion (TTS) systems are used by many Gram-negative pathogens to inject virulence proteins into the cells of their hosts. Several of these virulence effectors require TTS chaperones that maintain them in a secretion-competent state. Whereas most chaperones bind only one effector, Spa15

  5. Normal and abnormal secretion by haemopoietic cells

    Science.gov (United States)

    STINCHCOMBE, JANE C; GRIFFITHS, GILLIAN M

    2001-01-01

    The secretory lysosomes found in haemopoietic cells provide a very efficient mechanism for delivering the effector proteins of many immune cells in response to antigen recognition. Although secretion shows some similarities to the secretion of specialized granules in other secretory cell types, some aspects of secretory lysosome release appear to be unique to melanocytes and cells of the haemopoietic lineage. Mast cells and platelets have provided excellent models for studying secretion, but recent advances in characterizing the immunological synapse allow a very fine dissection of the secretory process in T lymphocytes. These studies show that secretory lysosomes are secreted from the centre of the talin ring at the synapse. Proper secretion requires a series of Rab and cytoskeletal elements which play critical roles in the specialized secretion of lysosomes in haemopoietic cells. PMID:11380687

  6. Melatonin Secretion Pattern in Critically Ill Patients

    DEFF Research Database (Denmark)

    Boyko, Yuliya; Holst, René; Jennum, Poul

    2017-01-01

    effect of remifentanil on melatonin secretion. We found that the risk of atypical sleep compared to normal sleep was significantly lower (p REM) sleep was only observed during the nonsedation period. We found preserved diurnal pattern of melatonin...... secretion in these patients. Remifentanil did not affect melatonin secretion but was associated with lower risk of atypical sleep pattern. REM sleep was only registered during the period of nonsedation.......Critically ill patients have abnormal circadian and sleep homeostasis. This may be associated with higher morbidity and mortality. The aims of this pilot study were (1) to describe melatonin secretion in conscious critically ill mechanically ventilated patients and (2) to describe whether melatonin...

  7. Efficient multiparty quantum-secret-sharing schemes

    International Nuclear Information System (INIS)

    Xiao Li; Deng Fuguo; Long Guilu; Pan Jianwei

    2004-01-01

    In this work, we generalize the quantum-secret-sharing scheme of Hillery, Buzek, and Berthiaume [Phys. Rev. A 59, 1829 (1999)] into arbitrary multiparties. Explicit expressions for the shared secret bit is given. It is shown that in the Hillery-Buzek-Berthiaume quantum-secret-sharing scheme the secret information is shared in the parity of binary strings formed by the measured outcomes of the participants. In addition, we have increased the efficiency of the quantum-secret-sharing scheme by generalizing two techniques from quantum key distribution. The favored-measuring-basis quantum-secret-sharing scheme is developed from the Lo-Chau-Ardehali technique [H. K. Lo, H. F. Chau, and M. Ardehali, e-print quant-ph/0011056] where all the participants choose their measuring-basis asymmetrically, and the measuring-basis-encrypted quantum-secret-sharing scheme is developed from the Hwang-Koh-Han technique [W. Y. Hwang, I. G. Koh, and Y. D. Han, Phys. Lett. A 244, 489 (1998)] where all participants choose their measuring basis according to a control key. Both schemes are asymptotically 100% in efficiency, hence nearly all the Greenberger-Horne-Zeilinger states in a quantum-secret-sharing process are used to generate shared secret information

  8. Thymidine secretion by hybridoma and myeloma cells

    International Nuclear Information System (INIS)

    Spilsberg, Bjorn; Rise, Frode; Petersen, Dirk; Nissen-Meyer, Jon

    2006-01-01

    Secretion of thymidine appeared to be a common property of hybridoma and myeloma cells, but not of other cell types, which were tested. Of three hybridoma cell lines tested, all secreted thymidine in amounts resulting in the accumulation of thymidine to concentrations of 10-20 μM in the culture medium. Also three of five myeloma cell lines that were analyzed secrete thymidine, but none of the other cell types that were studied. Thymidine was purified to homogeneity (4 mg purified from 3 l of culture medium) and identified as such by nuclear magnetic resonance spectroscopy. The cells that secreted thymidine showed high resistance to the growth inhibitory effect of thymidine

  9. Systematic high-yield production of human secreted proteins in Escherichia coli

    International Nuclear Information System (INIS)

    Dai Xueyu; Chen Qiang; Lian Min; Zhou Yanfeng; Zhou Mo; Lu Shanyun; Chen Yunjia; Luo Jingchu; Gu Xiaocheng; Jiang Ying; Luo Ming; Zheng Xiaofeng

    2005-01-01

    Human secreted proteins play a very important role in signal transduction. In order to study all potential secreted proteins identified from the human genome sequence, systematic production of large amounts of biologically active secreted proteins is a prerequisite. We selected 25 novel genes as a trial case for establishing a reliable expression system to produce active human secreted proteins in Escherichia coli. Expression of proteins with or without signal peptides was examined and compared in E. coli strains. The results indicated that deletion of signal peptides, to a certain extent, can improve the expression of these proteins and their solubilities. More importantly, under expression conditions such as induction temperature, N-terminus fusion peptides need to be optimized in order to express adequate amounts of soluble proteins. These recombinant proteins were characterized as well-folded proteins. This system enables us to rapidly obtain soluble and highly purified human secreted proteins for further functional studies

  10. Development of a Method to Monitor Gene Expression in Single Bacterial Cells During the Interaction With Plants and Use to Study the Expression of the Type III Secretion System in Single Cells of Dickeya dadantii in Potato

    Directory of Open Access Journals (Sweden)

    Zhouqi Cui

    2018-06-01

    Full Text Available Dickeya dadantii is a bacterial plant pathogen that causes soft rot disease on a wide range of host plants. The type III secretion system (T3SS is an important virulence factor in D. dadantii. Expression of the T3SS is induced in the plant apoplast or in hrp-inducing minimal medium (hrp-MM, and is repressed in nutrient-rich media. Despite the understanding of induction conditions, how individual cells in a clonal bacterial population respond to these conditions and modulate T3SS expression is not well understood. In our previous study, we reported that in a clonal population, only a small proportion of bacteria highly expressed T3SS genes while the majority of the population did not express T3SS genes under hrp-MM condition. In this study, we developed a method that enabled in situ observation and quantification of gene expression in single bacterial cells in planta. Using this technique, we observed that the expression of the T3SS genes hrpA and hrpN is restricted to a small proportion of D. dadantii cells during the infection of potato. We also report that the expression of T3SS genes is higher at early stages of infection compared to later stages. This expression modulation is achieved through adjusting the ratio of T3SS ON and T3SS OFF cells and the expression intensity of T3SS ON cells. Our findings not only shed light into how bacteria use a bi-stable gene expression manner to modulate an important virulence factor, but also provide a useful tool to study gene expression in individual bacterial cells in planta.

  11. Structure of AscE and Induced Burial Regions in AscE and AscG upon Formation of the Chaperone Needle-subunit Complex of Type III Secretion System in Aeromonas Hydrophila

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Y.; Yu, H; Leung, K; Sivaraman, J; Mok, Y

    2008-01-01

    In the type III secretion system (T3SS) of Aeromonas hydrophila, the putative needle complex subunit AscF requires both putative chaperones AscE and AscG for formation of a ternary complex to avoid premature assembly. Here we report the crystal structure of AscE at 2.7 A resolution and the mapping of buried regions of AscE, AscG, and AscF in the AscEG and AscEFG complexes using limited protease digestion. The dimeric AscE is comprised of two helix-turn-helix monomers packed in an antiparallel fashion. The N-terminal 13 residues of AscE are buried only upon binding with AscG, but this region is found to be nonessential for the interaction. AscE functions as a monomer and can be coexpressed with AscG or with both AscG and AscF to form soluble complexes. The AscE binding region of AscG in the AscEG complex is identified to be within the N-terminal 61 residues of AscG. The exposed C-terminal substrate-binding region of AscG in the AscEG complex is induced to be buried only upon binding to AscF. However, the N-terminal 52 residues of AscF remain exposed even in the ternary AscEFG complex. On the other hand, the 35-residue C-terminal region of AscF in the complex is resistant to protease digestion in the AscEFG complex. Site-directed mutagenesis showed that two C-terminal hydrophobic residues, Ile83 and Leu84, of AscF are essential for chaperone binding.

  12. Ghrelin: ghrelin as a regulatory Peptide in growth hormone secretion.

    Science.gov (United States)

    Khatib, Nazli; Gaidhane, Shilpa; Gaidhane, Abhay M; Khatib, Mahanaaz; Simkhada, Padam; Gode, Dilip; Zahiruddin, Quazi Syed

    2014-08-01

    Ghrelin is a type of growth hormone (GH) secretagogue that stimulates the release of GH. It is a first hormone linking gastrointestinal-pituitary axis. This review highlights the interaction of ghrelin with GHRH and somatostatin to regulate the secretion of GH and intends to explore the possible physiological role of the ghrelin-pituitary-GH axis linkage system. Ghrelin is highly conserved among species and is classified into octanoylated (C8:0), decanoylated (C10:0), decenoylated (C10:1) and nonacylated,ghrelin. Acylated ghrelin is the major active form of human ghrelin. The primary production site of ghrelin is the stomach, and it interacts with stomach ghrelin as well as hypothalamic GHRH and somatostatin in the regulation of pituitary GH secretion. Ghrelin stimulate GH release through the GHS receptor to increase intracellular Ca2+ ([Ca2+] levels via IP3 signal transduction pathway. Ghrelin is a specific endogenous ligand for the GHS receptor and provides a definitive proof of the occurance of a GHS-GHS receptor signalling system in the regulation of GH secretion. Studies suggests that ghrelin is a powerful pharmacological agent that exerts a potent, time-dependent stimulation of pulsatile secretion of GH.

  13. Secret Key Agreement: Fundamental Limits and Practical Challenges

    KAUST Repository

    Rezki, Zouheir

    2017-02-15

    Despite the tremendous progress made toward establishing PLS as a new paradigm to guarantee security of communication systems at the physical layerthere is a common belief among researchers and industrials that there are many practical challenges that prevent PLS from flourishing at the industrial scale. Most secure message transmission constructions available to date are tied to strong assumptions on CSI, consider simple channel models and undermine eavesdropping capabilities; thus compromising their practical interest to a big extent. Perhaps arguably, the most likely reasonable way to leverage PLS potential in securing modern wireless communication systems is via secret-key agreement. In the latter setting, the legitimate parties try to agree on a key exploiting availability of a public channel with high capacity which is also accessible to the eavesdropper. Once a key is shared by the legitimate parties, they may use it in a one-time pad encryption, for instance. In this article, we investigate two performance limits of secret-key agreement communications; namely, the secret-key diversity-multiplexing trade-off and the effect of transmit correlation on the secretkey capacity. We show via examples how secretkey agreement offers more flexibility than secure message transmissions. Finally, we explore a few challenges of secret-key agreement concept and propose a few guidelines to overturn them.

  14. Report on achievements in fiscal 1998. Venture business growing type consortium - small business creating infrastructure (Development of simplified analysis system by using bio-markers of internal secretion disturbing substances - environmental hormone acting substances); 1998 nendo naibunpi kakuran busshitsu (kankyo hormone sayo busshitsu) no bio marker ni yoru kanben bunseki system no kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Using the vitellogenin levels in male fishes as a parameter of pollution caused by internal secretion disturbing substances would allow collective measurement of compounding action of pollutants, acquisition of time averaged values, and large reduction in analysis cost. The present research and development works are intended to put such technological seeds into practical use, and promote its proliferation. The following subjects were implemented: (1) fabrication of effective anti-bodies, (2) their application to fresh water fishes, salmon, and trout, (3) their application to sea water fishes, (4) effects on mummichog and medaka, (5) correlation between spawning actions and vitellogenin manifestation in male fish, (6) discussions on chemical analysis methods and the correlativity therewith, and (7) establishment of methods for field investigation and evaluation. In Item (1), an ELISA system using vitellogenin anti-bodies of different fishes was established. A universal anti-body reacting commonly to all of fish vitellogenins was developed. In Items (2), (3) and (4), an evaluation system was established on actions of internal secretion disturbing substances on sea water fish and fresh water fish by using fish vitellogenins. In Item (5), effects on spawning of medaka, and effects on procreation activities (sterility) were evaluated by using vitellogenin. (NEDO)

  15. "The Secret Garden": A Literary Journey.

    Science.gov (United States)

    Jordan, Anne Devereaux

    1998-01-01

    Outlines the life of Frances Hodgson Burnett, author of "The Secret Garden." Argues that it not only tells an enthralling tale, but takes readers on a journey through the history of English literature. Discusses the gothic tradition and romanticism of "The Secret Garden." Lists classic elements in the book and offers five ideas…

  16. Gastric secretion elicited by conditioning in rats.

    Science.gov (United States)

    Caboclo, José Liberato Ferreira; Cury, Francico de Assis; Borin, Aldenis Albanese; Caboclo, Luís Otávio Sales Ferreira; Ribeiro, Maria Fernanda Sales Caboclo; de Freitas, Pedro José; Andersson, Sven

    2009-01-01

    To investigate whether interdigestive gastric acid secretion can be controlled by a possible memory-related cortical mechanism. To evaluate gastric secretion in rats, we used a methodology that allows gastric juice collection in rats in their habitual conditions (without any restraining) by pairing sound as the conditioning stimulus (CS) and food as the unconditioning stimulus (US). The levels of gastric acid secretion under basal conditions and under sound stimulation were recorded and the circulating gastrin levels determined. When the gastric juice was collected in the course of the conditioning procedure, the results showed that under noise stimulation a significant increase in gastric acid secretion occurred after 10 days of conditioning (p<0.01). The significance was definitively demonstrated after 13 days of conditioning (p<0.001). Basal secretions of the conditioned rats reached a significant level after 16 days of conditioning. The levels of noise-stimulated gastric acid secretion were the highest so far described in physiological experiments carried out in rats and there were no significant increases in the circulating gastrin levels. The results point to the important role played by cortical structures in the control of interdigestive gastric acid secretion in rats. If this mechanism is also present in humans, it may be involved in diseases caused by inappropriate gastric acid secretion during the interprandial periods.

  17. Dig It! The Secrets of Soil

    Science.gov (United States)

    It! The Secrets of Soil Come and Explore! Discover the amazing world of soils with images and information from the Dig It! The Secrets of Soil exhibit from the Smithsonian's National Museum of Natural and new web content will be added over the coming months including a new soil blog. New Interactives

  18. Ionizing radiation in secret services' conspirative actions

    International Nuclear Information System (INIS)

    Vogel, H.; Lotz, P.; Vogel, B.

    2007-01-01

    Introduction: The death of Litvinenko has been reported by the media. It has raised the question whether this case had been unique. The fall of the wall has allowed a glimpse in the planning and comporting of a secret service. Material and method: Documents of the secret service of the former German democratic republic (GDR), books of defectors, and media reports about secret service actions with radiating substances have been analyzed. Results: Since decades, secret services have been using radioactive nuclides and radiation for their tasks. Several killings with radiation have been reported. A complicated logistic had been developed. Conclusion: Only singular cases of the employment of radiating substances have become known. It is probable that the majority rests unknown. Government support seems necessary in secret services' conspirative actions with radiating substance

  19. Unconventional Pathways of Secretion Contribute to Inflammation

    Directory of Open Access Journals (Sweden)

    Michael J. D. Daniels

    2017-01-01

    Full Text Available In the conventional pathway of protein secretion, leader sequence-containing proteins leave the cell following processing through the endoplasmic reticulum (ER and Golgi body. However, leaderless proteins also enter the extracellular space through mechanisms collectively known as unconventional secretion. Unconventionally secreted proteins often have vital roles in cell and organism function such as inflammation. Amongst the best-studied inflammatory unconventionally secreted proteins are interleukin (IL-1β, IL-1α, IL-33 and high-mobility group box 1 (HMGB1. In this review we discuss the current understanding of the unconventional secretion of these proteins and highlight future areas of research such as the role of nuclear localisation.

  20. Secret-key expansion from covert communication

    Science.gov (United States)

    Arrazola, Juan Miguel; Amiri, Ryan

    2018-02-01

    Covert communication allows the transmission of messages in such a way that it is not possible for adversaries to detect that the communication is occurring. This provides protection in situations where knowledge that two parties are talking to each other may be incriminating to them. In this work, we study how covert communication can be used for a different purpose: secret key expansion. First, we show that any message transmitted in a secure covert protocol is also secret and therefore unknown to an adversary. We then propose a covert communication protocol where the amount of key consumed in the protocol is smaller than the transmitted key, thus leading to secure secret key expansion. We derive precise conditions for secret key expansion to occur, showing that it is possible when there are sufficiently low levels of noise for a given security level. We conclude by examining how secret key expansion from covert communication can be performed in a computational security model.

  1. Current Therapies That Modify Glucagon Secretion

    DEFF Research Database (Denmark)

    Grøndahl, Magnus F.; Keating, Damien J.; Vilsbøll, Tina

    2017-01-01

    and provide insights into how antidiabetic drugs influence glucagon secretion as well as a perspective on the future of glucagon-targeting drugs. Recent Findings: Several older as well as recent investigations have evaluated the effect of antidiabetic agents on glucagon secretion to understand how glucagon...... may be involved in the drugs’ efficacy and safety profiles. Based on these findings, modulation of glucagon secretion seems to play a hitherto underestimated role in the efficacy and safety of several glucose-lowering drugs. Summary: Numerous drugs currently available to diabetologists are capable...... of altering glucagon secretion: metformin, sulfonylurea compounds, insulin, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors and amylin mimetics. Their diverse effects on glucagon secretion are of importance for their individual efficacy...

  2. Characterization of a secreted Chlamydia protease

    DEFF Research Database (Denmark)

    Shaw, A.C.; Vandahl, B.B.; Larsen, M.R.

    2002-01-01

    Chlamydiae are obligate intracellular bacteria that are important human pathogens. The Chlamydia genomes contain orthologues to secretion apparatus proteins from other intracellular bacteria, but only a few secreted proteins have been identified. Most likely, effector proteins are secreted in order...... to promote infection. Effector proteins cannot be identified by motif or similarity searches. As a new strategy for identification of secreted proteins we have compared 2D-PAGE profiles of [35S]-labelled Chlamydia proteins from whole lysates of infected cells to 2D-PAGE profiles of proteins from purified...... Chlamydia. Several secretion candidates from Chlamydia trachomatis D and Chlamydia pneumoniae were detected by this method. Two protein spots were identified among the candidates. These represent fragments of the 'chlamydial protease- or proteasome-like activity factor' (CPAF) and were clearly present in 2D...

  3. On Secret Sharing with Nonlinear Product Reconstruction

    DEFF Research Database (Denmark)

    Cascudo Pueyo, Ignacio; Cramer, Ronald; Mirandola, Diego

    2015-01-01

    Multiplicative linear secret sharing is a fundamental notion in the area of secure multiparty computation and, since recently, in the area of two-party cryptography as well. In a nutshell, this notion guarantees that the product of two secrets is obtained as a linear function of the vector......-necessarily-linear “product reconstruction function.” Is the resulting notion equivalent to multiplicative linear secret sharing? We show the (perhaps somewhat counterintuitive) result that this relaxed notion is strictly more general. Concretely, fix a finite field ${\\mathbb F}_q$ as the base field over which linear secret...... sharing is considered. Then we show there exists an (exotic) linear secret sharing scheme with an unbounded number of players $n$ such that it has $t$-privacy with $t = \\Omega(n)$ and such that it does admit a product reconstruction function, yet this function is necessarily nonlinear. In addition, we...

  4. Pituitary-hormone secretion by thyrotropinomas.

    Science.gov (United States)

    Roelfsema, Ferdinand; Kok, Simon; Kok, Petra; Pereira, Alberto M; Biermasz, Nienke R; Smit, Jan W; Frolich, Marijke; Keenan, Daniel M; Veldhuis, Johannes D; Romijn, Johannes A

    2009-01-01

    Hormone secretion by somatotropinomas, corticotropinomas and prolactinomas exhibits increased pulse frequency, basal and pulsatile secretion, accompanied by greater disorderliness. Increased concentrations of growth hormone (GH) or prolactin (PRL) are observed in about 30% of thyrotropinomas leading to acromegaly or disturbed sexual functions beyond thyrotropin (TSH)-induced hyperthyroidism. Regulation of non-TSH pituitary hormones in this context is not well understood. We there therefore evaluated TSH, GH and PRL secretion in 6 patients with up-to-date analytical and mathematical tools by 24-h blood sampling at 10-min intervals in a clinical research laboratory. The profiles were analyzed with a new deconvolution method, approximate entropy, cross-approximate entropy, cross-correlation and cosinor regression. TSH burst frequency and basal and pulsatile secretion were increased in patients compared with controls. TSH secretion patterns in patients were more irregular, but the diurnal rhythm was preserved at a higher mean with a 2.5 h phase delay. Although only one patient had clinical acromegaly, GH secretion and IGF-I levels were increased in two other patients and all three had a significant cross-correlation between the GH and TSH. PRL secretion was increased in one patient, but all patients had a significant cross-correlation with TSH and showed decreased PRL regularity. Cross-ApEn synchrony between TSH and GH did not differ between patients and controls, but TSH and PRL synchrony was reduced in patients. We conclude that TSH secretion by thyrotropinomas shares many characteristics of other pituitary hormone-secreting adenomas. In addition, abnormalities in GH and PRL secretion exist ranging from decreased (joint) regularity to overt hypersecretion, although not always clinically obvious, suggesting tumoral transformation of thyrotrope lineage cells.

  5. Multiplexed Quantitation of Intraphagocyte Mycobacterium tuberculosis Secreted Protein Effectors

    Directory of Open Access Journals (Sweden)

    Fadel Sayes

    2018-04-01

    Full Text Available Summary: The pathogenic potential of Mycobacterium tuberculosis largely depends on ESX secretion systems exporting members of the multigenic Esx, Esp, and PE/PPE protein families. To study the secretion and regulation patterns of these proteins while circumventing immune cross-reactions due to their extensive sequence homologies, we developed an approach that relies on the recognition of their MHC class II epitopes by highly discriminative T cell receptors (TCRs of a panel of T cell hybridomas. The latter were engineered so that each expresses a unique fluorescent reporter linked to specific antigen recognition. The resulting polychromatic and multiplexed imaging assay enabled us to measure the secretion of mycobacterial effectors inside infected host cells. We applied this novel technology to a large panel of mutants, clinical isolates, and host-cell types to explore the host-mycobacteria interplay and its impact on the intracellular bacterial secretome, which also revealed the unexpected capacity of phagocytes from lung granuloma to present mycobacterial antigens via MHC class II. : Sayes et al. develop an approach to express distinct fluorescent reporters that is based on the recognition of specific Mycobacterium tuberculosis MHC class II epitopes by highly discriminative T cell hybridomas. This multiplexed technology allows the study of secretion, subcellular location, and regulation patterns of these instrumental protein members. Keywords: mycobacterium tuberculosis, type VII secretion systems, intracellular bacteria, T-cell hybridomas, mycobacterial virulence factors, bacterial antigen presentation, lentiviral vectors, reporter T cells, in vivo antigen presentation, protein localization

  6. Impaired insulin secretion and glucose intolerance in synaptotagmin-7 null mutant mice

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Lao, Ye; Maximov, Anton

    2008-01-01

    and insulin release. Here, we show that synaptotagmin-7 is required for the maintenance of systemic glucose tolerance and glucose-stimulated insulin secretion. Mutant mice have normal insulin sensitivity, insulin production, islet architecture and ultrastructural organization, and metabolic and calcium...... secretion in pancreatic beta-cells. Of these other synaptotagmins, synaptotagmin-7 is one of the most abundant and is present in pancreatic beta-cells. To determine whether synaptotagmin-7 regulates Ca(2+)-dependent insulin secretion, we analyzed synaptotagmin-7 null mutant mice for glucose tolerance...... responses but exhibit impaired glucose-induced insulin secretion, indicating a calcium-sensing defect during insulin-containing secretory granule exocytosis. Taken together, our findings show that synaptotagmin-7 functions as a positive regulator of insulin secretion and may serve as a calcium sensor...

  7. Application of native signal sequences for recombinant proteins secretion in Pichia pastoris

    DEFF Research Database (Denmark)

    Borodina, Irina; Do, Duy Duc; Eriksen, Jens C.

    Background Methylotrophic yeast Pichia pastoris is widely used for recombinant protein production, largely due to its ability to secrete correctly folded heterologous proteins to the fermentation medium. Secretion is usually achieved by cloning the recombinant gene after a leader sequence, where...... alpha‐mating factor (MF) prepropeptide from Saccharomyces cerevisiae is most commonly used. Our aim was to test whether signal peptides from P. pastoris native secreted proteins could be used to direct secretion of recombinant proteins. Results Eleven native signal peptides from P. pastoris were tested...... by optimization of expression of three different proteins in P. pastoris. Conclusions Native signal peptides from P. pastoris can be used to direct secretion of recombinant proteins. A novel USER‐based P. pastoris system allows easy cloning of protein‐coding gene with the promoter and leader sequence of choice....

  8. A two-dimensional electrophoretic profile of the proteins secreted by Herbaspirillum seropedicae strain Z78.

    Science.gov (United States)

    Chaves, Daniela Fojo Seixas; de Souza, Emanuel Maltempi; Monteiro, Rose Adele; de Oliveira Pedrosa, Fábio

    2009-11-02

    Herbaspirillum seropedicae is an endophytic bacterium that associates with rice, sugarcane and other economically important crops. Secreted proteins play a key role in the plant-bacterial interaction. Using 2D electrophoresis and peptide mass fingerprint mass spectrometry, 63 protein spots representing 41 different secreted proteins were identified during growth of H. seropedicae under nitrogen-sufficient conditions. In silico analysis showed that 25.4% of the proteins had signal peptides and 15.9% were predicted to be non-classically secreted. Among the most abundant were flagellar components and ABC-type transport system proteins. Nine secreted proteins had also been identified in the cellular proteome, suggesting that they also play a role in the extracellular environment. No type III secreted proteins were detected by comparison of the wild type strain with an hrcN mutant strain.

  9. Bidirectional regulation of bakuchiol, an estrogenic-like compound, on catecholamine secretion

    International Nuclear Information System (INIS)

    Mao, Haoping; Wang, Hong; Ma, Shangwei; Xu, Yantong; Zhang, Han; Wang, Yuefei; Niu, Zichang; Fan, Guanwei; Zhu, Yan; Gao, Xiu Mei

    2014-01-01

    Excess or deficiency of catecholamine (CA) secretion was related with several diseases. Recently, estrogen and phytoestrogens were reported to regulate the activity of CA system. Bakuchiol is a phytoestrogen isolated from the seeds of Psoralea corylifolia L. (Leguminosae) which has been used in Traditional Chinese medicine as a tonic or aphrodisiac. In the present study, bovine adrenal medullary cells were employed to investigate the effects and mechanisms of bakuchiol on the regulation of CA secretion. Further, its anti-depressant like and anti-stress effects were evaluated by using behavioral despair and chronic immobilization stress models. Our results indicated that bakuchiol showed bidirectional regulation on CA secretion. It stimulated basal CA secretion in a concentration dependent manner (p + (p + induced CA secretion was related with reduction of intracellular calcium rise. In vivo experiments, we found that bakuchiol significantly reduced immobilization time in behavioral despair mouse (p < 0.05 or 0.01), and plasma epinephrine (E) and norepinephrine (NE) levels in chronic immobilization stress (p < 0.05). Overall, these results present a bidirectional regulation of bakuchiol on CA secretion which indicated that bakuchiol may exert anti-stress and the potential anti-depressant-like effects. - Highlights: • Bakuchiol stimulated basal catecholamine secretion. • Bakuchiol inhibited various secretagogues induced catecholamine secretion. • Bakuchiol may have anti-stress and the potential anti-depression-like effects

  10. Proinflammatory Cytokine Infusion Attenuates LH's Feedforward on Testosterone Secretion: Modulation by Age

    Science.gov (United States)

    Yang, Rebecca; Roelfsema, Ferdinand; Takahashi, Paul

    2016-01-01

    Context: In the experimental animal, inflammatory signals quench LH's feedforward drive of testosterone (T) secretion and appear to impair GnRH-LH output. The degree to which such suppressive effects operate in the human is not known. Objective: To test the hypothesis that IL-2 impairs LH's feedforward drive on T and T's feedback inhibition of LH secretion in healthy men. Setting: Mayo Center for Translational Science Activities. Patients or Other Participants: A total of 35 healthy men, 17 young and 18 older. Interventions: Randomized prospective double-blind saline-controlled study of IL-2 infusion in 2 doses with concurrent 10-minute blood sampling for 24 hours. Main Outcome Measures: Deconvolution analysis of LH and T secretion. Results: After saline injection, older compared with young men exhibited reduced LH feedforward drive on T secretion (P feedback inhibition of LH secretion (P feedforward onto T secretion declined markedly especially in young subjects (P feedback on LH secretion especially in older volunteers. Conclusion: This investigation confirms combined feedforward and feedback deficits in older relative to young men given saline and demonstrates 1) joint mechanisms by which IL-2 enforces biochemical hypogonadism, viz, combined feedforward block and feedback amplification; and 2) unequal absolute inhibition of T and LH secretion by IL-2 in young and older men. These outcomes establish that the male gonadal axis is susceptible to dual-site suppression by a prototypic inflammatory mediator. Thus, we postulate that selected ILs might also enforce male hypogonadism in chronic systemic inflammation. PMID:26600270

  11. Liposome-mediated amplified detection of cell-secreted matrix metalloproteinase-9†

    Science.gov (United States)

    Banerjee, Jayati; Hanson, Andrea J.; Nyren-Erickson, Erin K.; Ganguli, Bratati; Wagh, Anil; Muhonen, Wallace W.; Law, Benedict; Shabb, John B.; Srivastava, D. K.; Mallik, Sanku

    2018-01-01

    A liposome-based amplified detection system is presented for the cancer cell secreted pathogenic enzyme matrix metalloproteinase-9 which does not require the use of biological antibodies. PMID:20424776

  12. Metabolite secretion in microorganisms: the theory of metabolic overflow put to the test

    DEFF Research Database (Denmark)

    Pinu, Farhana R.; Granucci, Ninna; Daniell, James

    2018-01-01

    Introduction Microbial cells secrete many metabolites during growth, including important intermediates of the central carbon metabolism. This has not been taken into account by researchers when modeling microbial metabolism for metabolic engineering and systems biology studies. Materials and Meth...

  13. Secreted single‐stranded DNA is involved in the initial phase of biofilm formation by Neisseria gonorrhoeae

    DEFF Research Database (Denmark)

    Zweig, Maria; Schork, Sabine; Koerdt, Andrea

    2014-01-01

    plays an important role in biofilm formation. Many clinical isolates contain a gonococcal genetic island that encodes a type IV secretion system (T4SS). The T4SS of N. gonorrhoeae strain MS11 secretes ssDNA directly into the medium. Biofilm formation, studied in continuous flow‐chamber systems...... was developed in which thermostable fluorescently labelled ssDNA‐ and ss/dsDNA‐binding proteins were used to visualize ssDNA and total DNA in biofilms and planktonic cultures. Remarkably, mainly dsDNA was detected in biofilms of the ssDNA secreting strain. We conclude that the secreted ssDNA facilitates initial...

  14. THE BUFFER CAPACITY OF AIRWAY EPITHELIAL SECRETIONS

    Directory of Open Access Journals (Sweden)

    Dusik eKim

    2014-06-01

    Full Text Available The pH of airway epithelial secretions influences bacterial killing and mucus properties and is reduced by acidic pollutants, gastric reflux, and respiratory diseases such as cystic fibrosis (CF. The effect of acute acid loads depends on buffer capacity, however the buffering of airway secretions has not been well characterized. In this work we develop a method for titrating micro-scale (30 µl volumes and use it to study fluid secreted by the human airway epithelial cell line Calu-3, a widely used model for submucosal gland serous cells. Microtitration curves revealed that HCO3- is the major buffer. Peak buffer capacity (β increased from 17 to 28 mM/pH during forskolin stimulation, and was reduced by >50% in fluid secreted by cystic fibrosis transmembrane conductance regulator (CFTR-deficient Calu-3 monolayers, confirming an important role of CFTR in HCO3- secretion. Back-titration with NaOH revealed non-volatile buffer capacity due to proteins synthesized and released by the epithelial cells. Lysozyme and mucin concentrations were too low to buffer Calu-3 fluid significantly, however model titrations of porcine gastric mucins at concentrations near the sol-gel transition suggest that mucins may contribute to the buffer capacity of ASL in vivo. We conclude that CFTR-dependent HCO3- secretion and epithelially-derived proteins are the predominant buffers in Calu-3 secretions.

  15. 76 FR 66940 - Privacy Act of 1974; Department of Homeland Security/United States Secret Service-004 Protection...

    Science.gov (United States)

    2011-10-28

    ... DEPARTMENT OF HOMELAND SECURITY Office of the Secretary [Docket No. DHS-2011-0083] Privacy Act of 1974; Department of Homeland Security/United States Secret Service--004 Protection Information System... Security (DHS)/United States Secret Service (USSS)-004 System name: DHS/USSS-004 Protection Information...

  16. Biliary and pancreatic secretions in abdominal irradiation

    International Nuclear Information System (INIS)

    Becciolini, A.; Cionini, L.; Cappellini, M.; Atzeni, G.

    1979-01-01

    The biliary and pancreatic secretions have been determined in patients given pelvic or para-aortic irradiation, with a dose of 50 Gy in the former group and between 36 and 40 Gy in the latter. A test meal containing polyethylene glycol (PEG) as reference substance was used. Each sample of the duodenal content was assayed for volume, PEG content, amylase and trypsin activity, pH and biliary secretion. No significant modifications of biliary and pancreatic secretions were demonstrated after irradiation, suggesting that these functions are not involved in the pathogenesis of the malabsorption radiation syndrome. (Auth.)

  17. [Secret drug tribulations and French legislation].

    Science.gov (United States)

    Charlot, Colette

    2002-01-01

    From an official Montpellier prefecture paper of 18th century, we are interested in a secret drug from Provence origin: the Irroë powder. This purgative will pass from "secret" drug status to "patent" drug. It's notoriety will come from its arrival to Paris. The law of 21th germinal year XI, the decret of 25 prairial year XIII and this of 18th 1810 imposed to give the drug composition to an official status; that examined and permit it's sale. This secret will be produce for half century.

  18. Air Force UAVs: The Secret History

    Science.gov (United States)

    2010-07-01

    iA Mitchell Institute Study i Air Force UAVs The Secret History A Mitchell Institute Study July 2010 By Thomas P. Ehrhard Report Documentation Page...DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Air Force UAVs The Secret History 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...opening phases of Operation Enduring Freedom in Afghanistan. By Thomas P. Ehrhard a miTchEll insTiTuTE sTudy July 2010 Air Force UAVs The Secret History

  19. Diversity and subcellular distribution of archaeal secreted proteins

    Directory of Open Access Journals (Sweden)

    Mechthild ePohlschroder

    2012-07-01

    Full Text Available Secreted proteins make up a significant percentage of a prokaryotic proteome and play critical roles in important cellular processes such as polymer degradation, nutrient uptake, signal transduction, cell wall biosynthesis and motility. The majority of archaeal proteins are believed to be secreted either in an unfolded conformation via the universally conserved Sec pathway or in a folded conformation via the Twin arginine transport (Tat pathway. Extensive in vivo and in silico analyses of N-terminal signal peptides that target proteins to these pathways have led to the development of computational tools that not only predict Sec and Tat substrates with high accuracy but also provide information about signal peptide processing and targeting. Predictions therefore include indications as to whether a substrate is a soluble secreted protein, a membrane or cell-wall anchored protein, or a surface structure subunit, and whether it is targeted for post-translational modification such as glycosylation or the addition of a lipid. The use of these in silico tools, in combination with biochemical and genetic analyses of transport pathways and their substrates, has resulted in improved predictions of the subcellular localization of archaeal secreted proteins, allowing for a more accurate annotation of archaeal proteomes, and has led to the identification of potential adaptations to extreme environments, as well as archaeal kingdom-specific pathways. A more comprehensive understanding of the transport pathways and post-translational modifications of secreted archaeal proteins will also generate invaluable insights that will facilitate the identification of commercially valuable archaeal enzymes and the development of heterologous systems in which to efficiently express them.

  20. Secretion of autoimmune antibodies in the human subcutaneous adipose tissue.

    Science.gov (United States)

    Frasca, Daniela; Diaz, Alain; Romero, Maria; Thaller, Seth; Blomberg, Bonnie B

    2018-01-01

    The adipose tissue (AT) contributes to systemic and B cell intrinsic inflammation, reduced B cell responses and secretion of autoimmune antibodies. In this study we show that adipocytes in the human obese subcutaneous AT (SAT) secrete several pro-inflammatory cytokines and chemokines, which contribute to the establishment and maintenance of local and systemic inflammation, and consequent suboptimal immune responses in obese individuals, as we have previously shown. We also show that pro-inflammatory chemokines recruit immune cells expressing the corresponding receptors to the SAT, where they also contribute to local and systemic inflammation, secreting additional pro-inflammatory mediators. Moreover, we show that the SAT generates autoimmune antibodies. During the development of obesity, reduced oxygen and consequent hypoxia and cell death lead to further release of pro-inflammatory cytokines, "self" protein antigens, cell-free DNA and lipids. All these stimulate class switch and the production of autoimmune IgG antibodies which have been described to be pathogenic. In addition to hypoxia, we have measured cell cytotoxicity and DNA damage mechanisms, which may also contribute to the release of "self" antigens in the SAT. All these processes are significantly elevated in the SAT as compared to the blood. We definitively found that fat-specific IgG antibodies are secreted by B cells in the SAT and that B cells express mRNA for the transcription factor T-bet and the membrane marker CD11c, both involved in the production of autoimmune IgG antibodies. Finally, the SAT also expresses RNA for cytokines known to promote Germinal Center formation, isotype class switch, and plasma cell differentiation. Our results show novel mechanisms for the generation of autoimmune antibody responses in the human SAT and allow the identification of new pathways to possibly manipulate in order to reduce systemic inflammation and autoantibody production in obese individuals.

  1. Type 1 Does The Two-Step: Type 1 Secretion Substrates With A Functional Periplasmic Intermediate.

    Science.gov (United States)

    Smith, Timothy J; Sondermann, Holger; O'Toole, George A

    2018-06-04

    Bacteria have evolved several secretion strategies for polling and responding to environmental flux and insult. Of these, the type 1 secretion system (T1SS) is known to secrete an array of biologically diverse proteins - from small < 10 kDa bacteriocins to gigantic adhesins with a mass over 1 MDa. For the last several decades T1SS have been characterized as a one-step translocation strategy whereby the secreted substrate is transported directly into the extracellular environment from the cytoplasm with no periplasmic intermediate. Recent phylogenetic, biochemical, and genetic evidence point to a distinct sub-group of T1SS machinery linked with a bacterial transglutaminase-like cysteine proteinase (BTLCP), which uses a two-step secretion mechanism. BTLCP-linked T1SS transport a class of repeats-in-toxin (RTX) adhesins that are critical for biofilm formation. The prototype of this RTX adhesin group, LapA of Pseudomonas fluorescens Pf0-1, uses a novel N-terminal retention module to anchor the adhesin at the cell surface as a secretion intermediate threaded through the outer membrane-localized, TolC-like protein LapE. This secretion intermediate is post-translationally cleaved by the BTLCP family LapG protein to release LapA from its cognate T1SS pore. Thus, secretion of LapA and related RTX adhesins into the extracellular environment appears to be a T1SS-mediated, two-step process that involves a periplasmic intermediate. In this review, we contrast the T1SS machinery and substrates of the BLTCP-linked two-step secretion process with those of the classical one-step T1SS to better understand the newly recognized and expanded role of this secretion machinery. Copyright © 2018 American Society for Microbiology.

  2. The Diversity-Multiplexing Tradeoff of Secret-Key Agreement over Multiple-Antenna Channels

    KAUST Repository

    Zorgui, Marwen

    2015-10-26

    We study the problem of secret-key agreement between two legitimate parties, Alice and Bob, in presence an of eavesdropper Eve. There is a public channel with unlimited capacity that is available to the legitimate parties and is also observed by Eve. Our focus is on Rayleigh fading quasi-static channels. The legitimate receiver and the eavesdropper are assumed to have perfect channel knowledge of their channels. We study the system in the high-power regime. First, we define the secret-key diversity gain and the secret-key multiplexing gain. Second, we establish the secret-key diversity multiplexing tradeoff (DMT) under no channel state information (CSI) at the transmitter (CSI-T). The eavesdropper is shown to “steal” only transmit antennas. We show that, likewise the DMT without secrecy constraint, the secret-key DMT is the same either with or without full channel state information at the transmitter. This insensitivity of secret-key DMT toward CSI-T features a fundamental difference between secret-key agreement and the wiretap channel, in which secret DMT depends heavily on CSI-T. Finally, we present several secret-key DMT-achieving schemes in case of full CSI-T. We argue that secret DMT-achieving schemes are also key DMT-achieving. Moreover, we show formally that artificial noise (AN), likewise zero-forcing (ZF), is DMT-achieving. We also show that the public feedback channel improves the outage performance without having any effect on the DMT.

  3. The Diversity-Multiplexing Tradeoff of Secret-Key Agreement over Multiple-Antenna Channels

    KAUST Repository

    Zorgui, Marwen; Rezki, Zouheir; Alomair, Basel; Alouini, Mohamed-Slim

    2015-01-01

    We study the problem of secret-key agreement between two legitimate parties, Alice and Bob, in presence an of eavesdropper Eve. There is a public channel with unlimited capacity that is available to the legitimate parties and is also observed by Eve. Our focus is on Rayleigh fading quasi-static channels. The legitimate receiver and the eavesdropper are assumed to have perfect channel knowledge of their channels. We study the system in the high-power regime. First, we define the secret-key diversity gain and the secret-key multiplexing gain. Second, we establish the secret-key diversity multiplexing tradeoff (DMT) under no channel state information (CSI) at the transmitter (CSI-T). The eavesdropper is shown to “steal” only transmit antennas. We show that, likewise the DMT without secrecy constraint, the secret-key DMT is the same either with or without full channel state information at the transmitter. This insensitivity of secret-key DMT toward CSI-T features a fundamental difference between secret-key agreement and the wiretap channel, in which secret DMT depends heavily on CSI-T. Finally, we present several secret-key DMT-achieving schemes in case of full CSI-T. We argue that secret DMT-achieving schemes are also key DMT-achieving. Moreover, we show formally that artificial noise (AN), likewise zero-forcing (ZF), is DMT-achieving. We also show that the public feedback channel improves the outage performance without having any effect on the DMT.

  4. Mutations in ppe38 block PE_PGRS secretion and increase virulence of Mycobacterium tuberculosis

    KAUST Repository

    Ates, Louis S.

    2018-01-12

    Mycobacterium tuberculosis requires a large number of secreted and exported proteins for its virulence, immune modulation and nutrient uptake. Most of these proteins are transported by the different type VII secretion systems1,2. The most recently evolved type VII secretion system, ESX-5, secretes dozens of substrates belonging to the PE and PPE families, which are named for conserved proline and glutamic acid residues close to the amino terminus3,4. However, the role of these proteins remains largely elusive1. Here, we show that mutations of ppe38 completely block the secretion of two large subsets of ESX-5 substrates, that is, PPE-MPTR and PE_PGRS, together comprising >80 proteins. Importantly, hypervirulent clinical M. tuberculosis strains of the Beijing lineage have such a mutation and a concomitant loss of secretion5. Restoration of PPE38-dependent secretion partially reverted the hypervirulence phenotype of a Beijing strain, and deletion of ppe38 in moderately virulent M. tuberculosis increased virulence. This indicates that these ESX-5 substrates have an important role in virulence attenuation. Phylogenetic analysis revealed that deletion of ppe38 occurred at the branching point of the ‘modern’ Beijing sublineage and is shared by Beijing outbreak strains worldwide, suggesting that this deletion may have contributed to their success and global distribution6,7.

  5. Mutations in ppe38 block PE_PGRS secretion and increase virulence of Mycobacterium tuberculosis.

    Science.gov (United States)

    Ates, Louis S; Dippenaar, Anzaan; Ummels, Roy; Piersma, Sander R; van der Woude, Aniek D; van der Kuij, Kim; Le Chevalier, Fabien; Mata-Espinosa, Dulce; Barrios-Payán, Jorge; Marquina-Castillo, Brenda; Guapillo, Carolina; Jiménez, Connie R; Pain, Arnab; Houben, Edith N G; Warren, Robin M; Brosch, Roland; Hernández-Pando, Rogelio; Bitter, Wilbert

    2018-02-01

    Mycobacterium tuberculosis requires a large number of secreted and exported proteins for its virulence, immune modulation and nutrient uptake. Most of these proteins are transported by the different type VII secretion systems 1,2 . The most recently evolved type VII secretion system, ESX-5, secretes dozens of substrates belonging to the PE and PPE families, which are named for conserved proline and glutamic acid residues close to the amino terminus 3,4 . However, the role of these proteins remains largely elusive 1 . Here, we show that mutations of ppe38 completely block the secretion of two large subsets of ESX-5 substrates, that is, PPE-MPTR and PE_PGRS, together comprising >80 proteins. Importantly, hypervirulent clinical M. tuberculosis strains of the Beijing lineage have such a mutation and a concomitant loss of secretion 5 . Restoration of PPE38-dependent secretion partially reverted the hypervirulence phenotype of a Beijing strain, and deletion of ppe38 in moderately virulent M. tuberculosis increased virulence. This indicates that these ESX-5 substrates have an important role in virulence attenuation. Phylogenetic analysis revealed that deletion of ppe38 occurred at the branching point of the 'modern' Beijing sublineage and is shared by Beijing outbreak strains worldwide, suggesting that this deletion may have contributed to their success and global distribution 6,7 .

  6. Mutations in ppe38 block PE_PGRS secretion and increase virulence of Mycobacterium tuberculosis

    KAUST Repository

    Ates, Louis S.; Dippenaar, Anzaan; Ummels, Roy; Piersma, Sander R.; van der Woude, Aniek D.; van der Kuij, Kim; Le Chevalier, Fabien; Mata-Espinosa, Dulce; Barrios-Payá n, Jorge; Marquina-Castillo, Brenda; Guapillo, Carolina; Jimé nez, Connie R.; Pain, Arnab; Houben, Edith N. G.; Warren, Robin M.; Brosch, Roland; Herná ndez-Pando, Rogelio; Bitter, Wilbert

    2018-01-01

    Mycobacterium tuberculosis requires a large number of secreted and exported proteins for its virulence, immune modulation and nutrient uptake. Most of these proteins are transported by the different type VII secretion systems1,2. The most recently evolved type VII secretion system, ESX-5, secretes dozens of substrates belonging to the PE and PPE families, which are named for conserved proline and glutamic acid residues close to the amino terminus3,4. However, the role of these proteins remains largely elusive1. Here, we show that mutations of ppe38 completely block the secretion of two large subsets of ESX-5 substrates, that is, PPE-MPTR and PE_PGRS, together comprising >80 proteins. Importantly, hypervirulent clinical M. tuberculosis strains of the Beijing lineage have such a mutation and a concomitant loss of secretion5. Restoration of PPE38-dependent secretion partially reverted the hypervirulence phenotype of a Beijing strain, and deletion of ppe38 in moderately virulent M. tuberculosis increased virulence. This indicates that these ESX-5 substrates have an important role in virulence attenuation. Phylogenetic analysis revealed that deletion of ppe38 occurred at the branching point of the ‘modern’ Beijing sublineage and is shared by Beijing outbreak strains worldwide, suggesting that this deletion may have contributed to their success and global distribution6,7.

  7. Proton pump inhibitors inhibit pancreatic secretion

    DEFF Research Database (Denmark)

    Wang, Jing; Barbuskaite, Dagne; Tozzi, Marco

    2015-01-01

    +/K+-ATPases are expressed and functional in human pancreatic ducts and whether proton pump inhibitors (PPIs) have effect on those. Here we show that the gastric HKα1 and HKβ subunits (ATP4A; ATP4B) and non-gastric HKα2 subunits (ATP12A) of H+/K+-ATPases are expressed in human pancreatic cells. Pumps have similar...... of major ions in secretion follow similar excretory curves in control and PPI treated animals. In addition to HCO3-, pancreas also secretes K+. In conclusion, this study calls for a revision of the basic model for HCO3- secretion. We propose that proton transport is driving secretion, and that in addition...

  8. Experimental Study on Gastric Juice Secretion by ...

    African Journals Online (AJOL)

    管理平台

    2012-05-29

    May 29, 2012 ... Study on stomach physiological functions by ... mechanism of regulating gastric electrical activity and gastric juice secretion might become true by the .... samples was used in comparism among these different groups.

  9. EPCRA Trade Secret Form Instructions (PDF)

    Science.gov (United States)

    Detail on what information is required for each section of the form. Only the specific chemical identity required to be disclosed in EPCRA sections 303, 311,312, and 313 submissions may be claimed trade secret on the EPCRA report.

  10. (LH) secretion in fasted prepubertal ewes

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-01-10

    Jan 10, 2012 ... decreased luteinizing hormone (LH) secretion in fasted prepubertal ewes .... kisspeptin-10 injection could restore the baseline levels of. LH changed by ..... Terasawa E (2005). Role of GABA in the mechanism of the onset of.

  11. Regulation of glucagon secretion by incretins

    DEFF Research Database (Denmark)

    Holst, Jens Juul; Christensen, M; Lund, A

    2011-01-01

    Glucagon secretion plays an essential role in the regulation of hepatic glucose production, and elevated fasting and postprandial plasma glucagon concentrations in patients with type 2 diabetes (T2DM) contribute to their hyperglycaemia. The reason for the hyperglucagonaemia is unclear, but recent...... studies have shown lack of suppression after oral but preserved suppression after isoglycaemic intravenous glucose, pointing to factors from the gut. Gastrointestinal hormones that are secreted in response to oral glucose include glucagon-like peptide-1 (GLP-1) that strongly inhibits glucagon secretion......, and GLP-2 and GIP, both of which stimulate secretion. When the three hormones are given together on top of isoglycaemic intravenous glucose, glucagon suppression is delayed in a manner similar to that observed after oral glucose. Studies with the GLP-1 receptor antagonist, exendin 9-39, suggest...

  12. Cortisol secretion in patients with normoprolactinemic amenorrhea

    DEFF Research Database (Denmark)

    Boesgaard, S; Hagen, C; Andersen, A N

    1988-01-01

    with normoprolactinemic amenorrhea have elevated basal serum cortisol, the reason probably being hypersecretion of corticotropin-releasing hormone. Secondly that dopaminergic blockade with metoclopramide stimulates ACTH and cortisol secretion in patients presumed to have raised dopaminergic activity....

  13. Cell Secretion: Current Structural and Biochemical Insights

    Directory of Open Access Journals (Sweden)

    Saurabh Trikha

    2010-01-01

    Full Text Available Essential physiological functions in eukaryotic cells, such as release of hormones and digestive enzymes, neurotransmission, and intercellular signaling, are all achieved by cell secretion. In regulated (calcium-dependent secretion, membrane-bound secretory vesicles dock and transiently fuse with specialized, permanent, plasma membrane structures, called porosomes or fusion pores. Porosomes are supramolecular, cup-shaped lipoprotein structures at the cell plasma membrane that mediate and control the release of vesicle cargo to the outside of the cell. The sizes of porosomes range from 150nm in diameter in acinar cells of the exocrine pancreas to 12nm in neurons. In recent years, significant progress has been made in our understanding of the porosome and the cellular activities required for cell secretion, such as membrane fusion and swelling of secretory vesicles. The discovery of the porosome complex and the molecular mechanism of cell secretion are summarized in this article.

  14. Cholecystokinin inhibits gastrin secretion independently of paracrine somatostatin secretion in the pig

    DEFF Research Database (Denmark)

    Schmidt, P T; Hansen, L; Hilsted, L

    2004-01-01

    BACKGROUND: Cholecystokinin inhibits the secretion of gastrin from antral G cells, an effect that is speculated to be mediated by D cells secreting somatostatin. The aim of the study was to test directly whether cholecystokinin inhibition of antral gastrin secretion is mediated by somatostatin....... METHODS: The effects of CCK on gastrin and somatostatin secretion were studied in isolated vascularly perfused preparations of pig antrum before and after immunoneutralization brought about by infusion of large amounts of a high affinity monoclonal antibody against somatostatin. RESULTS: CCK infusion...... at 10(-9) M and 10(-8) M decreased gastrin output to 70.5% +/- 7.6% (n = 8) and 76.3% +/- 3.6% (n = 7) of basal output, respectively. CCK at 10(-10) M had no effect (n = 6). Somatostatin secretion was dose-dependently increased by CCK infusion and increased to 268 +/- 38.2% (n = 7) of basal secretion...

  15. Secret Sharing Schemes and Advanced Encryption Standard

    Science.gov (United States)

    2015-09-01

    25 4.7 Computational Example . . . . . . . . . . . . . . . . . . . . . 26 5 Side-Channel Effect on Advanced Encryption Standard ( AES ) 31...improvements, and to build upon them to discuss the side-channel effects on the Advanced Encryption Standard ( AES ). The following questions are asked...secret sharing scheme? • Can the improvements to the current secret sharing scheme prove to be beneficial in strengthening/weakening AES encryption

  16. Matryoshka: Hiding Secret Communication in Plain Sight

    OpenAIRE

    Safaka, Iris; Fragouli, Christina; Argyraki, Katerina

    2016-01-01

    We want to enable a pair of communicating users to exchange secret messages while hiding the fact that secret communication is taking place. We propose a linguistic steganography approach, where each human message is hidden in another human-like message. A hard open question is how to keep the steganographic message small -- existing related tools tend to blow up its size, thereby revealing the use of steganography. We encrypt by compressing each message, mapping it to a plausible sequence of...

  17. Percolation of secret correlations in a network

    OpenAIRE

    Leverrier, Anthony; García-Patrón, Raúl

    2011-01-01

    In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks, more precisely the question of percolation of secret correlations in a network. It is known that entanglement percolation in quantum networks can display a highly nontrivial behavior depending on the topology of the network and on the presence of entanglement between the nodes. Here we show that this behavior, thought to be of a genuine quantum nature, also occurs in a...

  18. Percolation of secret correlations in a network

    Energy Technology Data Exchange (ETDEWEB)

    Leverrier, Anthony; Garcia-Patron, Raul [ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels (Barcelona) (Spain); Research Laboratory of Electronics, MIT, Cambridge, MA 02139 (United States) and Max-Planck Institut fur Quantenoptik, Hans-Kopfermann Str. 1, D-85748 Garching (Germany)

    2011-09-15

    In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks--more precisely, the question of percolation of secret correlations in a network. It is known that entanglement percolation in quantum networks can display a highly nontrivial behavior depending on the topology of the network and on the presence of entanglement between the nodes. Here we show that this behavior, thought to be of a genuine quantum nature, also occurs in a classical context.

  19. Percolation of secret correlations in a network

    International Nuclear Information System (INIS)

    Leverrier, Anthony; Garcia-Patron, Raul

    2011-01-01

    In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks--more precisely, the question of percolation of secret correlations in a network. It is known that entanglement percolation in quantum networks can display a highly nontrivial behavior depending on the topology of the network and on the presence of entanglement between the nodes. Here we show that this behavior, thought to be of a genuine quantum nature, also occurs in a classical context.

  20. Pituitary-hormone secretion by thyrotropinomas

    OpenAIRE

    Roelfsema, Ferdinand; Kok, Simon; Kok, Petra; Pereira, Alberto M.; Biermasz, Nienke R.; Smit, Jan W.; Frolich, Marijke; Keenan, Daniel M.; Veldhuis, Johannes D.; Romijn, Johannes A.

    2008-01-01

    Hormone secretion by somatotropinomas, corticotropinomas and prolactinomas exhibits increased pulse frequency, basal and pulsatile secretion, accompanied by greater disorderliness. Increased concentrations of growth hormone (GH) or prolactin (PRL) are observed in about 30% of thyrotropinomas leading to acromegaly or disturbed sexual functions beyond thyrotropin (TSH)-induced hyperthyroidism. Regulation of non-TSH pituitary hormones in this context is not well understood. We there therefore ev...

  1. Engineering 1-Alkene Biosynthesis and Secretion by Dynamic Regulation in Yeast

    DEFF Research Database (Denmark)

    Zhou, Yongjin J.; Hu, Yating; Zhu, Zhiwei

    2018-01-01

    strategy to control the expression of membrane enzyme and 1-alkene production and cell growth by relieving the possible toxicity of overexpressed membrane proteins. With these efforts, the engineered yeast cell factory produced 35.3 mg/L 1-alkenes with more than 80% being secreted. This represents a 10...... product secretion. Here, we engineered the budding yeast Saccharomyces cerevisiae to produce and secrete 1-alkenes by manipulation of the fatty acid metabolism, enzyme selection, engineering the electron transfer system and expressing a transporter. Furthermore, we implemented a dynamic regulation...

  2. An unexpected knock on Corrigan's secret door.

    Science.gov (United States)

    Woywodt, Alexander

    2010-10-01

    Corrigan's secret door describes a metaphorical escape route for busy physicians. The term was derived from the successful and exceptionally busy professional life of Irish physician Dominic John Corrigan (1802-80). It is claimed that Corrigan's outpatient clinic was so busy that he required a secret door in his consulting rooms to escape from the ever-growing queue of eager patients. The origins of this charming story are unknown, and the door may have never existed. However, at present, Corrigan's secret door is often quoted when busy physicians have their own little ways in surviving a stressful professional life. Generations of British-trained doctors have grown up with Corrigan's secret door, as it was featured in the introduction of the Oxford Handbook of Clinical Medicine. Accordingly, trainees as well as more senior doctors are often reminded that having a 'secret door' is vital in surviving in the medical profession. My own escape is through classical music and the violoncello, in particular. As the name implies, my own secret door is normally invisible to colleagues and patients. This little article is about a patient who found me out, and a reflection on the role of classical music and the cello in my professional life.

  3. Detector-device-independent quantum secret sharing with source flaws.

    Science.gov (United States)

    Yang, Xiuqing; Wei, Kejin; Ma, Haiqiang; Liu, Hongwei; Yin, Zhenqiang; Cao, Zhu; Wu, Lingan

    2018-04-10

    Measurement-device-independent entanglement witness (MDI-EW) plays an important role for detecting entanglement with untrusted measurement device. We present a double blinding-attack on a quantum secret sharing (QSS) protocol based on GHZ state. Using the MDI-EW method, we propose a QSS protocol against all detector side-channels. We allow source flaws in practical QSS system, so that Charlie can securely distribute a key between the two agents Alice and Bob over long distances. Our protocol provides condition on the extracted key rate for the secret against both external eavesdropper and arbitrary dishonest participants. A tight bound for collective attacks can provide good bounds on the practical QSS with source flaws. Then we show through numerical simulations that using single-photon source a secure QSS over 136 km can be achieved.

  4. Simulating cloud environment for HIS backup using secret sharing.

    Science.gov (United States)

    Kuroda, Tomohiro; Kimura, Eizen; Matsumura, Yasushi; Yamashita, Yoshinori; Hiramatsu, Haruhiko; Kume, Naoto

    2013-01-01

    In the face of a disaster hospitals are expected to be able to continue providing efficient and high-quality care to patients. It is therefore crucial for hospitals to develop business continuity plans (BCPs) that identify their vulnerabilities, and prepare procedures to overcome them. A key aspect of most hospitals' BCPs is creating the backup of the hospital information system (HIS) data at multiple remote sites. However, the need to keep the data confidential dramatically increases the costs of making such backups. Secret sharing is a method to split an original secret message so that individual pieces are meaningless, but putting sufficient number of pieces together reveals the original message. It allows creation of pseudo-redundant arrays of independent disks for privacy-sensitive data over the Internet. We developed a secret sharing environment for StarBED, a large-scale network experiment environment, and evaluated its potential and performance during disaster recovery. Simulation results showed that the entire main HIS database of Kyoto University Hospital could be retrieved within three days even if one of the distributed storage systems crashed during a disaster.

  5. Pharmacokinetics of natural and engineered secreted factors delivered by mesenchymal stromal cells.

    Directory of Open Access Journals (Sweden)

    Jessica S Elman

    Full Text Available Transient cell therapy is an emerging drug class that requires new approaches for pharmacological monitoring during use. Human mesenchymal stem cells (MSCs are a clinically-tested transient cell therapeutic that naturally secrete anti-inflammatory factors to attenuate immune-mediated diseases. MSCs were used as a proof-of-concept with the hypothesis that measuring the release of secreted factors after cell transplantation, rather than the biodistribution of the cells alone, would be an alternative monitoring tool to understand the exposure of a subject to MSCs. By comparing cellular engraftment and the associated serum concentration of secreted factors released from the graft, we observed clear differences between the pharmacokinetics of MSCs and their secreted factors. Exploration of the effects of natural or engineered secreted proteins, active cellular secretion pathways, and clearance mechanisms revealed novel aspects that affect the systemic exposure of the host to secreted factors from a cellular therapeutic. We assert that a combined consideration of cell delivery strategies and molecular pharmacokinetics can provide a more predictive model for outcomes of MSC transplantation and potentially other transient cell therapeutics.

  6. The Impact of ExoS on Pseudomonas aeruginosa Internalization by Epithelial Cells Is Independent of fleQ and Correlates with Bistability of Type Three Secretion System Gene Expression.

    Science.gov (United States)

    Kroken, Abby R; Chen, Camille K; Evans, David J; Yahr, Timothy L; Fleiszig, Suzanne M J

    2018-05-01

    Pseudomonas aeruginosa is internalized into multiple types of epithelial cell in vitro and in vivo and yet is often regarded as an exclusively extracellular pathogen. Paradoxically, ExoS, a type three secretion system (T3SS) effector, has antiphagocytic activities but is required for intracellular survival of P. aeruginosa and its occupation of bleb niches in epithelial cells. Here, we addressed mechanisms for this dichotomy using invasive (ExoS-expressing) P. aeruginosa and corresponding effector-null isogenic T3SS mutants, effector-null mutants of cytotoxic P. aeruginosa with and without ExoS transformation, antibiotic exclusion assays, and imaging using a T3SS-GFP reporter. Except for effector-null PA103, all strains were internalized while encoding ExoS. Intracellular bacteria showed T3SS activation that continued in replicating daughter cells. Correcting the fleQ mutation in effector-null PA103 promoted internalization by >10-fold with or without ExoS. Conversely, mutating fleQ in PAO1 reduced internalization by >10-fold, also with or without ExoS. Effector-null PA103 remained less well internalized than PAO1 matched for fleQ status, but only with ExoS expression, suggesting additional differences between these strains. Quantifying T3SS activation using GFP fluorescence and quantitative reverse transcription-PCR (qRT-PCR) showed that T3SS expression was hyperinducible for strain PA103Δ exoUT versus other isolates and was unrelated to fleQ status. These findings support the principle that P. aeruginosa is not exclusively an extracellular pathogen, with internalization influenced by the relative proportions of T3SS-positive and T3SS-negative bacteria in the population during host cell interaction. These data also challenge current thinking about T3SS effector delivery into host cells and suggest that T3SS bistability is an important consideration in studying P. aeruginosa pathogenesis. IMPORTANCE P. aeruginosa is often referred to as an extracellular

  7. Regulation of atrial natriuretic peptide (ANP) secretion

    International Nuclear Information System (INIS)

    Ruskoaho, H.; Toth, M.; Lang, R.E.; Unger, Th.; Garten, D.

    1986-01-01

    To investigate the role of calcium, protein kinase C and adenylate cyclase in the ANP secretion, the secretory responses from isolated perfused rat hearts to a calcium channel activator, Bay k8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluomethylphenyl)-2-pyridine-5-carboxylate), the calcium ionophore (A23187), the phorbol ester (12-0-tetradecanoylphorbol-13-acetate, TPA), and to forskolin were studied. ANP in perfusate was measured by radioimmunoassay 10 min before and during the infusion (30 min) of various agents at 2 min intervals. A23187 (5.7 x 10 -7 ) induced a sharp increase, whereas TPA (0.15 - 1.6 x 10 -7 ) caused a slowly progressive increase in ANP secretion. 4a-phorbol-12,13-didecanoate, a non-active phorbol ester, had no effect on ANP secretion. Bay k8644 (4 x 10 -7 ) and forskolin (1 x 10 -6 ) alone caused small but sustained increase in ANP secretion. The combination of TPA with Bay k8644, forskolin or A23187 stimulated ANP secretion higher than the calculated additive value for each agent. Dibuturyl-cAMP (1.6 x 10 -4 ) pretreatment also enhanced TPA-induced ANP release. 8-Bromo-cGMP (1.3 x 10 -4 ) and sodium nitroprusside (9 x 10 -5 ) alone had no effect, but both attenuated the TPA-induced ANP secretion. The results suggest that atrial cardiocytes possess at least two different secretory pathways for ANP secretion, which are probably dependent on protein kinase C and cyclic AMP

  8. Generation of Dipeptidyl Peptidase-IV-Inhibiting Peptides from β-Lactoglobulin Secreted by Lactococcus lactis

    Directory of Open Access Journals (Sweden)

    Suguru Shigemori

    2014-01-01

    Full Text Available Previous studies showed that hydrolysates of β-lactoglobulin (BLG prepared using gastrointestinal proteases strongly inhibit dipeptidyl peptidase-IV (DPP-IV activity in vitro. In this study, we developed a BLG-secreting Lactococcus lactis strain as a delivery vehicle and in situ expression system. Interestingly, trypsin-digested recombinant BLG from L. lactis inhibited DPP-IV activity, suggesting that BLG-secreting L. lactis may be useful in the treatment of type 2 diabetes mellitus.

  9. 5 CFR 1312.27 - Top secret control.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Top secret control. 1312.27 Section 1312... Classified Information § 1312.27 Top secret control. The EOP Security Officer serves as the Top Secret... Top Secret material. The ATSCOs will be responsible for the accountability and custodianship of Top...

  10. Secretion Trap Tagging of Secreted and Membrane-Spanning Proteins Using Arabidopsis Gene Traps

    Science.gov (United States)

    Andrew T. Groover; Joseph R. Fontana; Juana M. Arroyo; Cristina Yordan; W. Richard McCombie; Robert A. Martienssen

    2003-01-01

    Secreted and membrane-spanning proteins play fundamental roles in plant development but pose challenges for genetic identification and characterization. We describe a "secretion trap" screen for gene trap insertions in genes encoding proteins routed through the secretory pathway. The gene trap transposon encodes a ß-glucuronidase reporter enzyme...

  11. Role of adipose secreted factors and kisspeptin in the metabolic control of gonadotropin secretion and puberty

    Science.gov (United States)

    Factors secreted by adipose tissue continue to be discovered. Evidence indicates a strong link between neural influences and adipocyte expression and secretion of a wide array of cytokines, neurotrophic factors, growth factors, binding proteins, and neuropeptides. These “adipokines” are linked to im...

  12. Shared Secrets versus Secrets Kept Private Are Linked to Better Adolescent Adjustment

    Science.gov (United States)

    Frijns, Tom; Finkenauer, Catrin; Keijsers, Loes

    2013-01-01

    It is a household notion that secrecy is bad while sharing is good. But what about shared secrets? The present research adopts a functional analysis of sharing secrets, arguing that it should negate harmful consequences generally associated with secrecy and serves important interpersonal functions in adolescence. A survey study among 790 Dutch…

  13. Meaningful Share Generation for Increased Number of Secrets in Visual Secret-Sharing Scheme

    Directory of Open Access Journals (Sweden)

    Mustafa Ulutas

    2010-01-01

    Full Text Available This paper presents a new scheme for hiding two halftone secret images into two meaningful shares created from halftone cover images. Meaningful shares are more desirable than noise-like (meaningless shares in Visual Secret Sharing because they look natural and do not attract eavesdroppers' attention. Previous works in the field focus on either increasing number of secrets or creating meaningful shares for one secret image. The method outlined in this paper both increases the number of secrets and creates meaningful shares at the same time. While the contrast ratio of shares is equal to that of Extended Visual Cryptography, two secrets are encoded into two shares as opposed to one secret in the Extended Visual Cryptography. Any two natural-looking images can be used as cover unlike the Halftone Visual Cryptography method where one cover should be the negative of the other cover image and can only encode one secret. Effectiveness of the proposed method is verified by an experiment.

  14. Pancreatic bicarbonate secretion involves two proton pumps.

    Science.gov (United States)

    Novak, Ivana; Wang, Jing; Henriksen, Katrine L; Haanes, Kristian A; Krabbe, Simon; Nitschke, Roland; Hede, Susanne E

    2011-01-07

    Pancreas secretes fluid rich in digestive enzymes and bicarbonate. The alkaline secretion is important in buffering of acid chyme entering duodenum and for activation of enzymes. This secretion is formed in pancreatic ducts, and studies to date show that plasma membranes of duct epithelium express H(+)/HCO(3)(-) transporters, which depend on gradients created by the Na(+)/K(+)-ATPase. However, the model cannot fully account for high-bicarbonate concentrations, and other active transporters, i.e. pumps, have not been explored. Here we show that pancreatic ducts express functional gastric and non-gastric H(+)-K(+)-ATPases. We measured intracellular pH and secretion in small ducts isolated from rat pancreas and showed their sensitivity to H(+)-K(+) pump inhibitors and ion substitutions. Gastric and non-gastric H(+)-K(+) pumps were demonstrated on RNA and protein levels, and pumps were localized to the plasma membranes of pancreatic ducts. Quantitative analysis of H(+)/HCO(3)(-) and fluid transport shows that the H(+)-K(+) pumps can contribute to pancreatic secretion in several species. Our results call for revision of the bicarbonate transport physiology in pancreas, and most likely other epithelia. Furthermore, because pancreatic ducts play a central role in several pancreatic diseases, it is of high relevance to understand the role of H(+)-K(+) pumps in pathophysiology.

  15. Incretin hormone secretion over the day

    DEFF Research Database (Denmark)

    Ahren, B; Carr, RD; Deacon, Carolyn F.

    2010-01-01

    The two incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are key factors in the regulation of islet function and glucose metabolism, and incretin-based therapy for type 2 diabetes has gained considerable interest during recent years. Regulat......The two incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are key factors in the regulation of islet function and glucose metabolism, and incretin-based therapy for type 2 diabetes has gained considerable interest during recent years....... Regulation of incretin hormone secretion is less well characterized. The main stimulus for incretin hormone secretion is presence of nutrients in the intestinal lumen, and carbohydrate, fat as well as protein all have the capacity to stimulate GIP and GLP-1 secretion. More recently, it has been established...... that a diurnal regulation exists with incretin hormone secretion to an identical meal being greater when the meal is served in the morning compared to in the afternoon. Finally, whether incretin hormone secretion is altered in disease states is an area with, so far, controversial results in different studies...

  16. Cell secretion machinery: Studies using the AFM

    International Nuclear Information System (INIS)

    Jena, Bhanu P.

    2006-01-01

    A new field in biology, 'nano-cell biology', has emerged from the successful use of force microscopy in understanding the structure and dynamics of cells and biomolecules, at nm resolution and in real time. Atomic force microscopy, in combination with conventional tools and approaches (electron microscopy, electrophysiology, X-ray diffraction, photon correlation spectroscopy, mass spectroscopy, biochemistry, and molecular biology), has revealed for the first time, the universal molecular machinery and mechanism of secretion in cells. Secretion occurs in all living cells and involves the delivery of intracellular products to the cell exterior. Secretory products are packaged and stored in membranous sacs or vesicles within the cell. When the cell needs to secrete these products, the secretory vesicles containing them, dock and fuse at plasma membrane-associated supramolecular structures called Porosome, to release their contents. Specialized cells for neurotransmission, enzyme secretion, or hormone release utilize a highly regulated secretory process. During secretion, swelling of secretory vesicles results in a build-up of intravesicular pressure, allowing expulsion of vesicular contents. The extent of vesicle swelling dictates the amount of vesicular contents expelled. The discovery of the porosome as the universal secretory machinery, its isolation, its structure and dynamics at nm resolution and in real time, its biochemical composition and functional reconstitution into artificial lipid membrane, have been determined. The molecular mechanism of secretory vesicle swelling, and the fusion of opposing bilayers, i.e., the fusion of secretory vesicle membrane at the base of the porosome membrane, has also been resolved

  17. Macrophage-secreted factors induce adipocyte inflammation and insulin resistance

    International Nuclear Information System (INIS)

    Permana, Paska A.; Menge, Christopher; Reaven, Peter D.

    2006-01-01

    Macrophage infiltration into adipose tissue increases with obesity, a condition associated with low-grade inflammation and insulin resistance. We investigated the direct effects of macrophage-secreted factors on adipocyte inflammation and insulin resistance. 3T3-L1 adipocytes incubated with media conditioned by RAW264.7 macrophages (RAW-CM) showed dramatically increased transcription of several inflammation-related genes, greater nuclear factor kappa B (NF-κB) activity, and enhanced binding of U937 monocytes. All of these effects were prevented by co-incubation with pyrrolidinedithiocarbamate, an NF-κB inhibitor. Adipocytes incubated with RAW-CM also released more non-esterified fatty acids and this increased lipolysis was not suppressed by insulin. In addition, RAW-CM treatment decreased insulin-stimulated glucose uptake in adipocytes. Taken together, these results indicate that macrophage-secreted factors induce inflammatory responses and reduce insulin responsiveness in adipocytes. These effects of macrophage-secreted factors on adipocytes may contribute significantly to the systemic inflammation and insulin resistance associated with obesity

  18. Signaling Pathways in Exosomes Biogenesis, Secretion and Fate

    Directory of Open Access Journals (Sweden)

    Carla Emiliani

    2013-03-01

    Full Text Available Exosomes are small extracellular vesicles (30–100 nm derived from the endosomal system, which have raised considerable interest in the last decade. Several studies have shown that they mediate cell-to-cell communication in a variety of biological processes. Thus, in addition to cell-to-cell direct interaction or secretion of active molecules, they are now considered another class of signal mediators. Exosomes can be secreted by several cell types and retrieved in many body fluids, such as blood, urine, saliva and cerebrospinal fluid. In addition to proteins and lipids, they also contain nucleic acids, namely mRNA and miRNA. These features have prompted extensive research to exploit them as a source of biomarkers for several pathologies, such as cancer and neurodegenerative disorders. In this context, exosomes also appear attractive as gene delivery vehicles. Furthermore, exosome immunomodulatory and regenerative properties are also encouraging their application for further therapeutic purposes. Nevertheless, several issues remain to be addressed: exosome biogenesis and secretion mechanisms have not been clearly understood, and physiological functions, as well as pathological roles, are far from being satisfactorily elucidated.

  19. Neuroendocrine regulation of gonadotropin secretion in seasonally breeding birds

    Directory of Open Access Journals (Sweden)

    Takayoshi eUbuka

    2013-03-01

    Full Text Available Seasonally breeding birds detect environmental signals, such as light, temperature, food availability and presence of mates to time reproduction. Hypothalamic neurons integrate external and internal signals, and regulate reproduction by releasing neurohormones to the pituitary gland. The pituitary gland synthesizes and releases gonadotropins which in turn act on the gonads to stimulate gametogenesis and sex steroid secretion. Accordingly, how gonadotropin secretion is controlled by the hypothalamus is key to our understanding of the mechanisms of seasonal reproduction. A hypothalamic neuropeptide, gonadotropin-releasing hormone (GnRH, activates reproduction by stimulating gonadotropin synthesis and release. Another hypothalamic neuropeptide, gonadotropin-inhibitory hormone (GnIH, inhibits gonadotropin synthesis and release directly by acting on the pituitary gland or indirectly by decreasing the activity of GnRH neurons. Therefore, the next step to understand seasonal reproduction is to investigate how the activities of GnRH and GnIH neurons in the hypothalamus and their receptors in the pituitary gland are regulated by external and internal signals. It is possible that locally-produced triiodothyronine resulting from the action of type 2 iodothyronine deiodinase on thyroxine stimulates the release of gonadotropins, perhaps by action on GnRH neurons. The function of GnRH neurons is also regulated by transcription of the GnRH gene. Melatonin, a nocturnal hormone, stimulates the synthesis and release of GnIH and GnIH may therefore regulate a daily rhythm of gonadotropin secretion. GnIH may also temporally suppress gonadotropin secretion when environmental conditions are unfavorable. Environmental and social milieus fluctuate seasonally in the wild. Accordingly, complex interactions of various neuronal and hormonal systems need to be considered if we are to understand the mechanisms underlying seasonal reproduction.

  20. Adaptive Secret Sharing for Color Images

    Directory of Open Access Journals (Sweden)

    Jia-Hong Li

    2011-10-01

    Full Text Available A secret sharing model can secure a secret over multiple noise-like shadows and remain recoverable despite multiple shadow failures. Even if some of the shadows are compromised, the secret will not be revealed as long as the number of the compromised shadows is smaller than a pre-determined threshold. Moreover, there are some necessary details of concerns: the malicious tampering on shadows must be detectable; the shadows must be concealed in a camouflage image with adequate quality to reduce suspicion and possible attack; color image properties must be considered. In addition to these concerns, in this paper, an adaptable mechanism is further designed to balance the hiding quantity and the quality of camouflage images depending on different applications.This is an important and interesting aspect that has never been discussed in previous research.

  1. Hiding secret data into a carrier image

    Directory of Open Access Journals (Sweden)

    Ovidiu COSMA

    2012-06-01

    Full Text Available The object of steganography is embedding hidden information in an appropriate multimedia carrier, e.g., image, audio, or video. There are several known methods of solving this problem, which operate either in the space domain or in the frequency domain, and are distinguished by the following characteristics: payload, robustness and strength. The payload is the amount of secret data that can be embedded in the carrier without inducing suspicious artefacts, robustness indicates the degree in which the secret data is affected by the normal processing of the carrier e.g., compression, and the strength indicate how easy the presence of hidden data can be detected by steganalysis techniques. This paper presents a new method of hiding secret data into a digital image compressed by a technique based on the Discrete Wavelet Transform (DWT [2] and the Set Partitioning In Hierarchical Trees (SPIHT subband coding algorithm [6]. The proposed method admits huge payloads and has considerable strength.

  2. Quantum secret sharing with classical Bobs

    International Nuclear Information System (INIS)

    Li Lvzhou; Qiu Daowen; Mateus, Paulo

    2013-01-01

    Boyer et al (2007 Phys. Rev. Lett. 99 140501) proposed a novel idea of semi-quantum key distribution, where a key can be securely distributed between Alice, who can perform any quantum operation, and Bob, who is classical. Extending the ‘semi-quantum’ idea to other tasks of quantum information processing is of interest and worth considering. In this paper, we consider the issue of semi-quantum secret sharing, where a quantum participant Alice can share a secret key with two classical participants, Bobs. After analyzing the existing protocol, we propose a new protocol of semi-quantum secret sharing. Our protocol is more realistic, since it utilizes product states instead of entangled states. We prove that any attempt of an adversary to obtain information necessarily induces some errors that the legitimate users could notice. (paper)

  3. Measurement of secretion in nasal lavage

    DEFF Research Database (Denmark)

    Bisgaard, H; Krogsgaard, O W; Mygind, N

    1987-01-01

    1. The amount of admixture in nasal lavage fluids was determined by addition of 99mTc labelled albumin, providing a correction factor for measurements of cellular material and humoral substances in nasal lavage return as well as a quantitative measure of nasal secretions. 2. Albumin was chosen...... secretion to be carried out on the whole sample of lavage fluid, thereby avoiding the necessity of complete admixture between marker and lavage fluid which would be pertinent to marker molecules measured chemically. The radiation from a nasal lavage is minimal and the procedure is fully acceptable...... of the nose, yet not the oropharynx. 5. A dose related increase in nasal secretion harvested by the nasal lavage in 10 persons challenged with histamine chloride could be demonstrated by this technique. 6. It is concluded that the use of 99mTc-albumin in a nasal washing provides a safe, simple and quick...

  4. Apical secretion of apolipoproteins from enterocytes

    DEFF Research Database (Denmark)

    Danielsen, E M; Hansen, Gert Helge; Poulsen, Mona Dam

    1993-01-01

    Synthesis and secretion of apolipoproteins in pig small intestine was studied by pulse-chase labeling of jejunal segments, kept in organ culture. Apo A-1 and apo B-48 were the two major proteins released, constituting 25 and 10%, respectively, of the total amount of labeled protein in the mucosal...... in the soluble fraction, suggesting a basolateral secretion into the intercellular space, and both this accumulation and the release to the medium was prevented by culture at 20 degrees C. The specific radioactivity of apo A-1 and apo B-48 released to the medium was significantly higher than...... that enterocytes release most of their newly made free apo A-1 and a significant portion of apo B-48 by exocytosis via the brush border membrane into the intestinal lumen. Fat absorption reduced apolipoprotein secretion to the medium and induced the formation of chylomicrons, containing apo A-1 at their surface...

  5. Pancreatic exocrine secretion in atomic bomb survivors

    International Nuclear Information System (INIS)

    Hiraoka, Masataka; Kawanishi, Masahiro; Ohtaki, Megu

    1989-01-01

    This study was designed to examine the effect of A-bombing on pancreatic exocrine secretion in 6 A-bomb survivors (an average age of 57 years) and the age- and sex-matched non-exposed 6 persons (an average age of 58 years). Six A-bomb survivors consisted of: three who had been directly exposed to A-bombing, one who had entered the city within 3 days after bombing, one who had worked in caring for A-bomb survivors, and one who had later entered the city. Caerulein-Secretin test revealed no significant difference in the total secretion of lipase, maximum bicarbonate, amylase output, or lipase output between the exposed and non-exposed groups. The concentration of lipase ten min after stimulation was significantly decreased in the exposed group than the control group. This suggests that radiation may be responsible for abnormality in the ability of pancreatic exocrine secretion. (N.K.)

  6. Impaired Sympathoadrenal Axis Function Contributes to Enhanced Insulin Secretion in Prediabetic Obese Rats

    Directory of Open Access Journals (Sweden)

    Ana Eliza Andreazzi

    2011-01-01

    Full Text Available The involvement of sympathoadrenal axis activity in obesity onset was investigated using the experimental model of treating neonatal rats with monosodium L-glutamate. To access general sympathetic nervous system activity, we recorded the firing rates of sympathetic superior cervical ganglion nerves in animals. Catecholamine content and secretion from isolated adrenal medulla were measured. Intravenous glucose tolerance test was performed, and isolated pancreatic islets were stimulated with glucose and adrenergic agonists. The nerve firing rate of obese rats was decreased compared to the rate for lean rats. Basal catecholamine secretion decreased whereas catecholamine secretion induced by carbachol, elevated extracellular potassium, and caffeine in the isolated adrenal medulla were all increased in obese rats compared to control. Both glucose intolerance and hyperinsulinaemia were observed in obese rats. Adrenaline strongly inhibited glucose-induced insulin secretion in obese animals. These findings suggest that low sympathoadrenal activity contributes to impaired glycaemic control in prediabetic obese rats.

  7. Caught in the act: discovering secreted proteins from fungi and oomycetes in action

    DEFF Research Database (Denmark)

    Roth, Doris; Grell, Morten Nedergaard; Jensen, Annette Bruun

    Host-microbe relationships largely rely on secreted proteins like enzymes, virulence factors and antimicrobial peptides. To discover proteins secreted by microbe and host during the interaction with each other, we produced dual-organism cDNA libraries from three different fungus- or oomycete-infe......, by applying a similar strategy with a fungus-only library. As a result, we will show that our approach is widely applicable and allows us to deepen the understanding a variety of different host-microbe systems.......Host-microbe relationships largely rely on secreted proteins like enzymes, virulence factors and antimicrobial peptides. To discover proteins secreted by microbe and host during the interaction with each other, we produced dual-organism cDNA libraries from three different fungus- or oomycete...

  8. Loss of Cln3 impacts protein secretion in the social amoeba Dictyostelium.

    Science.gov (United States)

    Huber, Robert J

    2017-07-01

    Neuronal ceroid lipofuscinosis (NCL), also referred to as Batten disease, is the most common form of childhood neurodegeneration. Mutations in CLN3 cause the most prevalent subtype of the disease, which manifests during early childhood and is currently untreatable. The precise function of the CLN3 protein is still not known, which has inhibited the development of targeted therapies. In the social amoeba Dictyostelium discoideum, loss of the CLN3 homolog, Cln3, reduces adhesion during early development, which delays streaming and aggregation. The results of the present study indicate that this phenotype may be at least partly due to aberrant protein secretion in cln3 - cells. It is well-established that Cln3 localizes primarily to the contractile vacuole (CV) system in Dictyostelium, and to a lesser extent, compartments of the endocytic pathway. Intriguingly, the CV system has been linked to the secretion of proteins that do not contain a signal peptide for secretion (i.e., unconventional protein secretion). Proteins that do contain a signal peptide are secreted via a conventional mechanism involving the endoplasmic reticulum, transport through the Golgi, and secretion via vesicle release. In this study, Cln3 was observed to co-localize with the Golgi marker wheat germ agglutinin suggesting that Cln3 participates in both secretion mechanisms. Chimeras of wild-type (WT) and cln3 - cells displayed delayed streaming and aggregation, and interestingly, cln3 - cells starved in conditioned media (CM) harvested from starving WT cells showed near normal timing of streaming and aggregation suggesting aberrant protein secretion in Cln3-deficient cells. Based on these observations, LC-MS/MS was used to reveal the protein content of CM from starved cells (mass spectrometry data are available via ProteomeXchange with identifier PXD004897). A total of 450 proteins were detected in WT and cln3 - CM, of which 3 were absent in cln3 - CM. Moreover, 12 proteins that were present in

  9. Role of Nitric Oxide in the Regulation of Renin and Vasopressin Secretion

    Science.gov (United States)

    Reid, Ian A.

    1994-01-01

    Research during recent years has established nitric oxide as a unique signaling molecule that plays important roles in the regulation of the cardiovascular, nervous, immune, and other systems. Nitric oxide has also been implicated in the control of the secretion of hormones by the pancreas, hypothalamus, and anterior pituitary gland, and evidence is accumulating that it contributes to the regulation of the secretion of renin and vasopressin, hormones that play key roles in the control of sodium and water balance. Several lines of evidence have implicated nitric oxide in the control of renin secretion. The enzyme nitric oxide synthase is present in vascular and tubular elements of the kidney, particularly in cells of the macula densa, a structure that plays an important role in the control of renin secretion. Guanylyl cyclase, a major target for nitric oxide, is also present in the kidney. Drugs that inhibit nitric oxide synthesis generally suppress renin release in vivo and in vitro, suggesting a stimulatory role for the L-arginine/nitric oxide pathway in the control of renin secretion. Under some conditions, however, blockade of nitric oxide synthesis increases renin secretion. Recent studies indicate that nitric oxide not only contributes to the regulation of basal renin secretion, but also participates in the renin secretory responses to activation of the renal baroreceptor, macula densa, and beta adrenoceptor mechanisms that regulate renin secretion. Histochemical and immunocytochemical studies have revealed the presence of nitric oxide synthase in the supraoptic and paraventricular nuclei of the hypothalamus and in the posterior pituitary gland. Colocalization of nitric oxide synthase and vasopressin has been demonstrated in some hypothalamic neurons. Nitric oxide synthase activity in the hypothalamus and pituitary is increased by maneuvers known to stimulate vasopressin secretion, including salt loading and dehydration, Administration of L-arginine and nitric

  10. Analysis of Secreted Proteins Using SILAC

    DEFF Research Database (Denmark)

    Henningsen, Jeanette; Blagoev, Blagoy; Kratchmarova, Irina

    2014-01-01

    Secreted proteins serve a crucial role in the communication between cells, tissues, and organs. Proteins released to the extracellular environment exert their function either locally or at distant points of the organism. Proteins are secreted in a highly dynamic fashion by cells and tissues...... in the body responding to the stimuli and requirements presented by the extracellular milieu. Characterization of secretomes derived from various cell types has been performed using different quantitative mass spectrometry-based proteomics strategies, several of them taking advantage of labeling with stable...

  11. [Secretion of growth hormone in hyperthyroidism].

    Science.gov (United States)

    Hervás, F; Morreale de Escobar, G; Escobar Del Rey, F; Pozuelo, V

    1976-01-01

    The authors studied growth hormone (GH) secretion in a group of adult controls and another group of hyperthyroid patients after stimulation with intravenous insulin-induced (0,1 IU/kg) hypoglycemia, aiming to clear out the problem of discrepancies in literature concerning GH secretion in hyperthyroidism. They concluded that in this syndrome, GH levels are significantly higher than those of controls. The GH releasing response is normal, though it could be expected to be decreased due to decreased pituitary GH contents as a result of permanent somatotrophic cell stimulation.

  12. On the regulation of ghrelin secretion

    International Nuclear Information System (INIS)

    Schmidt, A.

    2003-04-01

    The newly discovered endogenous ligand of the growth hormone secretagogue receptor, ghrelin, is not only a potent stimulus for growth hormone secretion, but exerts also potent orexigenic (appetite stimulatory) effects. The purpose of this thesis was to elucidate the mechanisms underlying the regulation of this peptide in three different studies. Ghrelin serum levels were analyzed with a commercially available radioimmunoassay (RIA). In 18 patients on chronic hemodialysis ghrelin levels were investigated and acetomorphine parameters were determined in order to correlate the nutritional status to the ghrelin serum levels. The potential elimination of ghrelin during dialysis was also tested. Ghrelin levels were significantly elevated compared to controls. No correlation was found between Ghrelin serum levels and anthropometric parameters. It can be speculated that chronic hemodialysis patients are not only resistant to growth hormone, but also to ghrelin. In 8 healthy volunteers a potential involvement of ghrelin in the response of growth hormone to acute exercise was tested. During three different exercise intensities (low, submaximal and maximal exercise) ghrelin levels were measured. No changes in ghrelin plasma concentrations could be detected. These findings suggest that ghrellin is not involved in the growth hormone response to acute exercise. The purpose of the third study was to enlighten the mechanisms underlying the postprandial decrease of ghrelin. During a double-blind placebo-controlled study increasing systemic glucose concentrations were attained with infusion of glucose, in order to represent fasting and postprandial conditions. Ghrelin levels were studied during coinfusion of insulin, somatostatin and placebo. It could be demonstrated that, the regulation of the postprandial decrease in ghrelin is not regulated by insulin or glucose, but by somatostatin. (author)

  13. An ancestral role for the mitochondrial pyruvate carrier in glucose-stimulated insulin secretion

    Directory of Open Access Journals (Sweden)

    Kyle S. McCommis

    2016-08-01

    Full Text Available Objective: Transport of pyruvate into the mitochondrial matrix by the Mitochondrial Pyruvate Carrier (MPC is an important and rate-limiting step in its metabolism. In pancreatic β-cells, mitochondrial pyruvate metabolism is thought to be important for glucose sensing and glucose-stimulated insulin secretion. Methods: To evaluate the role that the MPC plays in maintaining systemic glucose homeostasis, we used genetically-engineered Drosophila and mice with loss of MPC activity in insulin-producing cells. Results: In both species, MPC deficiency results in elevated blood sugar concentrations and glucose intolerance accompanied by impaired glucose-stimulated insulin secretion. In mouse islets, β-cell MPC-deficiency resulted in decreased respiration with glucose, ATP-sensitive potassium (KATP channel hyperactivity, and impaired insulin release. Moreover, treatment of pancreas-specific MPC knockout mice with glibenclamide, a sulfonylurea KATP channel inhibitor, improved defects in islet insulin secretion and abnormalities in glucose homeostasis in vivo. Finally, using a recently-developed biosensor for MPC activity, we show that the MPC is rapidly stimulated by glucose treatment in INS-1 insulinoma cells suggesting that glucose sensing is coupled to mitochondrial pyruvate carrier activity. Conclusions: Altogether, these studies suggest that the MPC plays an important and ancestral role in insulin-secreting cells in mediating glucose sensing, regulating insulin secretion, and controlling systemic glycemia. Keywords: Stimulus-coupled secretion, Insulin, β-Cell, Diabetes, Pyruvate, Mitochondria, Drosophila

  14. Adrenergic system participation on LH secretion in pre-pubertal Nelore heifers Participação do sistema adrenérgico na secreção de LH, em novilhas nelores

    Directory of Open Access Journals (Sweden)

    Guilherme Paula Nogueira

    2008-12-01

    Full Text Available The aim of this study was to evaluate the response of clonidine administration (alfa-adrenoceptor agonist, 10g/kg body weight, i.v. and blood collected every 15 min for 4 h thereafter on luteinizing hormone (LH secretion in B. indicus pre-pubertal heifers at 8, 12 e 15 months of age. LH was quantified by RIA, sensitivity (0.05 ng/mL and coefficient of variation (20.39%. Alfa-adrenoceptor action (clonidine reduced (P<0,05 basal LH and time to greatest peak occurrence at 15 months-old and increased (P>0,05 peak total area and area of highest peak of LH secretion to 8 months-old. The results suggest reduced hypothalamic sensibility by gonadal steroid in pre-pubertal Nelore heifer maturation sexual and clonidine neurotransmitter participation, either stimulating or inhibiting LH secretion.Objetivou-se com este trabalho investigar a variação na secreção do hormônio luteinizante (LH em resposta ao tratamento com clonidina (agonista alfa-adrenérgico, 10µg/kg, i.v., amostras 15 min por 4h, em novilhas da raça Nelore pré-púberes aos 8, 12 e 15 meses de idade. A concentração de LH foi quantificada por radioimunoensaio, sensibilidade de 0,05 ng/mL e coeficiente de variação de 20,39%. A ativação de receptores alfa-adrenérgicos por intermédio da clonidina diminuiu (P<0,05 a concentração de LH e o tempo necessário para o aparecimento do maior pico de LH aos 15 meses de idade e aumentou (P>0,05 a área total e área do maior pico de secreção de LH aos 8 meses de idade. Os resultados indicam diminuição da sensibilidade do hipotálamo aos esteróides gonadais durante o processo de maturação sexual nas novilhas da raça Nelore e a participação da clonidina como neurotransmissora.

  15. Changes in the 5-HT2A receptor system in the pre-mammillary hypothalamus of the ewe are related to regulation of LH pulsatile secretion by an endogenous circannual rhythm

    Directory of Open Access Journals (Sweden)

    Karsch Fred J

    2003-01-01

    Full Text Available Abstract Background We wanted to determine if changes in the expression of serotonin 2A receptor (5HT2A receptor gene in the premammillary hypothalamus are associated with changes in reproductive neuroendocrine status. Thus, we compared 2 groups of ovariectomized-estradiol-treated ewes that expressed high vs low LH pulsatility in two different paradigms (2 groups per paradigm: (a refractoriness (low LH secretion or not (high LH secretion to short days in pineal-intact Ile-de-France ewes (RSD and (b endogenous circannual rhythm (ECR in free-running pinealectomized Suffolk ewes in the active or inactive stage of their reproductive rhythm. Results In RSD ewes, density of 5HT2A receptor mRNA (by in situ hybridization was significantly higher in the high LH group (25.3 ± 1.4 vs 21.4 ± 1.5 grains/neuron, P 3H-Ketanserin binding (a specific radioligand of the median part of the premammillary hypothalamus tended to be higher in the high group (29.1 ± 4.0 vs 24.6 ± 4.2 fmol/mg tissu-equivalent; P A receptor mRNA and 3H-Ketanserin binding were both significantly higher in the high LH group (20.8 ± 1.6 vs 17.0 ± 1.5 grains/neuron, P Conclusions We conclude that these higher 5HT2A receptor gene expression and binding activity of 5HT2A receptor in the premammillary hypothalamus are associated with stimulation of LH pulsatility expressed before the development of refractoriness to short days and prior to the decline of reproductive neuroendocrine activity during expression of the endogenous circannual rhythm.

  16. Secret Codes, Remainder Arithmetic, and Matrices.

    Science.gov (United States)

    Peck, Lyman C.

    This pamphlet is designed for use as enrichment material for able junior and senior high school students who are interested in mathematics. No more than a clear understanding of basic arithmetic is expected. Students are introduced to ideas from number theory and modern algebra by learning mathematical ways of coding and decoding secret messages.…

  17. The Best Kept Secret in Gifted Education

    Science.gov (United States)

    Alvino, James

    2004-01-01

    It is perhaps one of the best-kept secrets in educating gifted high school youth, and yet for 45 years, Hugh O'Brian Youth Leadership (HOBY) has been going strong, "Motivating Tomorrow's Leaders Today." After spending nine inspirational days in 1958 with Albert Schweitzer (Nobel Prize physician and philosopher) at his clinic in the African jungle,…

  18. Factors influencing insulin secretion from encapsulated islets

    NARCIS (Netherlands)

    de Haan, BJ; Faas, MM; de Vos, P

    2003-01-01

    Adequate regulation of glucose levels by a microencapsulated pancreatic islet graft requires a minute-to-minute regulation of blood glucose. To design such a transplant, it is mandatory to have sufficient insight in factors influencing the kinetics of insulin secretion by encapsulated islets. The

  19. Secretion Of Methionine By Microorganisms Associated With ...

    African Journals Online (AJOL)

    methionine were secreted after 96 hours and 72 hours respectively by the lactobacilli and Leuconostoc sp. Since lactic acid bacteria are micro-aerophilic, it is suggested that lactic acid bacteria (the two lactobacilli and Leuconostoc sp.), which are the major organisms involved in cassava fermentation for garri production, ...

  20. Employees, Trade Secrets and Restrictive Covenants

    NARCIS (Netherlands)

    Kamperman Sanders, Anselm; Heath, C.

    2017-01-01

    The book covers the protection of trade secrets and the law on post-contractual non-compete clauses (restrictive covenants) in an employment context. The topic is approached on an international and comparative level (chapters 1–3 and 10), and by way of country reports covering several European and

  1. The secret of the blue fog

    Science.gov (United States)

    Henrich, Oliver; Marenduzzo, Davide

    2017-04-01

    Why certain liquids turn blue when cooled was a mystery that stumped scientists for more than a century. As Oliver Henrich and Davide Marenduzzo explain, solving the secret of the “blue fog” proved to be an intellectual tour de force - and one that could lead to new types of display devices

  2. Surfactant secretion and clearance in the newborn

    International Nuclear Information System (INIS)

    Stevens, P.A.; Wright, J.R.; Clements, J.A.

    1989-01-01

    Pregnant rabbits (30 days) were injected intravenously with [3H]choline 8 h before delivery. The fetuses were delivered, and lung lavage and lamellar body phospholipids (PL) were analyzed. Some newborns also received radioactively labeled surfactant intratracheally on delivery and were permitted to breathe. With time, intratracheal label decreased in lavage and appeared in the lamellar body fraction, and intravenous label accumulated in both pools. Using a tracer analysis for non-steady state, we calculated surfactant secretion and clearance rates for the newborn period. Before birth, both rates rose slightly from 1.8 micrograms PL.g body wt-1.h-1 at 6 h before birth to 7.3 at birth. Immediately after birth, secretion rate rose to 37.7 micrograms PL.g body wt-1.h-1. Between 1.5 and 2 h after birth it fell to a minimum of 1.8 micrograms PL.g body wt-1.h-1 and then rose slowly to 6.0 at 12 h. After birth, clearance rate increased less than secretion rate (maximum 24.7 micrograms PL.g body wt-1.h-1 shortly after birth) then followed the same pattern but did not balance secretion rate in the 1st day

  3. Multiple Ca2+ sensors in secretion

    DEFF Research Database (Denmark)

    Walter, Alexander M; Groffen, Alexander J; Sørensen, Jakob Balslev

    2011-01-01

    Regulated neurotransmitter secretion depends on Ca(2+) sensors, C2 domain proteins that associate with phospholipids and soluble N-ethylmaleimide-sensitive fusion attachment protein receptor (SNARE) complexes to trigger release upon Ca(2+) binding. Ca(2+) sensors are thought to prevent spontaneous...

  4. Secret Shopping as User Experience Assessment Tool

    Science.gov (United States)

    Boyce, Crystal M.

    2015-01-01

    Secret shopping is a form of unobtrusive evaluation that can be accomplished with minimal effort, but still produce rich results. With as few as 11 shoppers, the author was able to identify trends in user satisfaction with services provided across two entry-level desks at Illinois Wesleyan University's The Ames Library. The focus of this secret…

  5. Regulated Mucin Secretion from Airway Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Kenneth Bruce Adler

    2013-09-01

    Full Text Available Secretory epithelial cells of the proximal airways synthesize and secrete gel-forming polymeric mucins. The secreted mucins adsorb water to form mucus that is propelled by neighboring ciliated cells, providing a mobile barrier which removes inhaled particles and pathogens from the lungs. Several features of the intracellular trafficking of mucins make the airway secretory cell an interesting comparator for the cell biology of regulated exocytosis. Polymeric mucins are exceedingly large molecules (up to 3x10^6 D per monomer whose folding and initial polymerization in the ER requires the protein disulfide isomerase Agr2. In the Golgi, mucins further polymerize to form chains and possibly branched networks comprising more than 20 monomers. The large size of mucin polymers imposes constraints on their packaging into transport vesicles along the secretory pathway. Sugar side chains account for >70% of the mass of mucins, and their attachment to the protein core by O-glycosylation occurs in the Golgi. Mature polymeric mucins are stored in large secretory granules ~1 um in diameter. These are translocated to the apical membrane to be positioned for exocytosis by cooperative interactions among MARCKS, cysteine string protein (CSP, HSP70 and the cytoskeleton. Mucin granules undergo exocytic fusion with the plasma membrane at a low basal rate and a high stimulated rate. Both rates are mediated by a regulated exocytic mechanism as indicated by phenotypes in both basal and stimulated secretion in mice lacking Munc13-2, a sensor of the second messengers calcium and diacylglycerol (DAG. Basal secretion is induced by low levels of activation of P2Y2 purinergic and A3 adenosine receptors by extracellular ATP released in paracrine fashion and its metabolite adenosine. Stimulated secretion is induced by high levels of the same ligands, and possibly by inflammatory mediators as well. Activated receptors are coupled to phospholipase C by Gq, resulting in the

  6. Secret key rates in quantum key distribution using Renyi entropies

    Energy Technology Data Exchange (ETDEWEB)

    Abruzzo, Silvestre; Kampermann, Hermann; Mertz, Markus; Bratzik, Sylvia; Bruss, Dagmar [Institut fuer Theoretische Physik III, Heinrich-Heine-Universitaet Duesseldorf (Germany)

    2010-07-01

    The secret key rate r of a quantum key distribution protocol depends on the involved number of signals and the accepted ''failure probability''. We reconsider a method to calculate r focusing on the analysis of the privacy amplification given by R. Renner and R. Koenig (2005). This approach involves an optimization problem with an objective function depending on the Renyi entropy of the density operator describing the classical outcomes and the eavesdropper system. This problem is analyzed for a generic class of QKD protocols and the current research status is presented.

  7. Establishment of an inducing medium for type III effector secretion in Xanthomonas campestris pv. campestris

    Directory of Open Access Journals (Sweden)

    Guo-Feng Jiang

    2013-09-01

    Full Text Available It is well known that the type III secretion system (T3SS and type III (T3 effectors are essential for the pathogenicity of most bacterial phytopathogens and that the expression of T3SS and T3 effectors is suppressed in rich media but induced in minimal media and plants. To facilitate in-depth studies on T3SS and T3 effectors, it is crucial to establish a medium for T3 effector expression and secretion. Xanthomonas campestris pv. campestris (Xcc is a model bacterium for studying plant-pathogen interactions. To date no medium for Xcc T3 effector secretion has been defined. Here, we compared four minimal media (MME, MMX, XVM2, and XOM2 which are reported for T3 expression induction in Xanthomonas spp. and found that MME is most efficient for expression and secretion of Xcc T3 effectors. By optimization of carbon and nitrogen sources and pH value based on MME, we established XCM1 medium, which is about 3 times stronger than MME for Xcc T3 effectors secretion. We further optimized the concentration of phosphate, calcium, and magnesium in XCM1 and found that XCM1 with a lower concentration of magnesium (renamed as XCM2 is about 10 times as efficient as XCM1 (meanwhile, about 30 times stronger than MME. Thus, we established an inducing medium XCM2 which is preferred for T3 effector secretion in Xcc.

  8. Novel insulin from the bullfrog: its structure and function in protein secretion by hepatocytes

    International Nuclear Information System (INIS)

    Hulsebus, J.J.

    1987-01-01

    Bullfrog insulin was extracted and purified from the pancreas of Rana catesbeiana adults using gel filtration and reverse phase high performance liquid chromatography. Amino acid analysis of bullfrog insulin revealed 52 amino acids instead of the most common number of 51. The most unique features of bullfrog insulin is a two amino acid extension on the amino terminus (A1) of the A chain. This is the only insulin to date that has an extension at this position. Bullfrog and porcine insulin increase protein secretion from bullfrog adult and three developmental stages of tadpole hepatocytes in a totally defined, serum-free culture system. The hormone slightly stimulates protein secretion by premetamorphic and early prometamorphic tadpoles. Late prometamorphic tadpoles respond to bullfrog and porcine insulin with higher concentrations of secreted protein than either of the two previous developmental stages. Insulin treated adult hepatocytes secrete significantly higher concentrations of protein than any of the tadpole stages. 35 S-methionine and 35 S-cysteine were added to the culture medium for twelve hours. Proteins secreted into the medium were separated using SDS polyacrylamide linear gradient gels. Densitometer scans of autoradiograms did not show an increases in any specific proteins, but did show a generalized increase in all secreted proteins for both adults, and tadpoles

  9. Mechanism of cellular secretion studied by high resolution soft-x-ray microscopy

    International Nuclear Information System (INIS)

    Loo, B.W. Jr.; Meyer-Ilse, W.; Rothman, S.S.

    1997-01-01

    The secretion of proteins is a fundamental cellular process. The physical and biochemical mechanisms that underlie this process have been studied with the view that they can serve as a general model for how cells transport many different substances to and through their various compartments and to the external environment. In this work, the authors study the secretion of digestive enzymes by the acinar cell of the mammalian pancreas. This is the classical system for studying such processes. The proteins that digest food are stored in approximately micrometer sized vesicles, zymogen granules, within these cells. There are two explanations for how these proteins are transported from within the granules to the exterior of the cell during the process of secretion. One proposes that whole granules are lost from the cell in discrete events, and the other proposes that partial and gradual emptying of the granules accounts for protein secretion. Of course, both mechanisms may occur. The authors are attempting to assess to what degree each of these mechanisms account for protein secretion by the organ. In order to do so, the authors have been determining whether physical changes in the granules, such as mass loss, occur during secretion as the second model predicts, or if there is a simple reduction in the number of granules as predicted by the first model

  10. Angiotensin-(1-7) attenuates hyposmolarity-induced ANP secretion via the Na+-K+ pump.

    Science.gov (United States)

    Shah, Amin; Oh, Young-Bin; Shan, Gao; Song, Chang Ho; Park, Byung-Hyun; Kim, Suhn Hee

    2010-09-01

    The alteration in osmolarity challenges cell volume regulation, a vital element for cell survival. Hyposmolarity causes an increase in cell volume. Recently, it has been reported that the renin-angiotensin system (RAS) plays a role in cell volume regulation. We investigated the effect of angiotensin-(1-7) [Ang-(1-7)] on hyposmolarity-induced atrial natriuretic peptide (ANP) secretion in normal and diabetic (DM) rat atria and modulation of the effect of Ang-(1-7) by the Na(+)-K(+) pump. Using isolated control rat atria, we observed that perfusion of hyposmotic solution into the atria increased ANP secretion. When Ang-(1-7) [0.1 microM or 1 microM] was perfused in a hyposmolar solution, it decreased the hyposmolarity-induced ANP secretion in a dose-dependent manner. This effect of Ang-(1-7) could be mediated by the Na(+)-K(+) pump, since ouabain, an Na(+)-K(+) pump inhibitor, significantly decreased the effect of Ang-(1-7) on hyposmolarity-induced ANP secretion. In contrast, N(omega) Nitro-l-arginine methyl ester hydrochloride (l-NAME) did not modify the effect of Ang-(1-7) on the hyposmolarity-induced ANP secretion. Interestingly, the ANP secretion was increased robustly by the perfusion of the hyposmolar solution in the DM atria, as compared to the control atria. However, the inhibitory effect of Ang-(1-7) on the hyposmolarity-induced ANP secretion was not observed in the DM atria. In the DM atria, atrial contractility was significantly increased. Taken together, we concluded that Ang-(1-7) attenuated hyposmolarity-induced ANP secretion via the Na(+)-K(+) pump and a lack of Ang-(1-7) response in DM atria may partly relate to change in Na(+)-K(+) pump activity. Copyright 2010 Elsevier Inc. All rights reserved.

  11. Effect of adrenal hormones on thyroid secretion and thyroid hormones on adrenal secretion in the sheep.

    Science.gov (United States)

    Falconer, I R; Jacks, F

    1975-01-01

    1. Previous work has shown that after stressful stimuli, sheep initially secrete increased amounts of thyroid hormone, at a time when adrenal secretion is also elevated. 2. This study was designed to evaluate (a) any short-term activation or inhibition of thyroid secretion by exogenous cortisol or ACTH administered in quantities comparable to those secreted after stress in sheep and (b) any short-term effect that exogenous thyroxine or triiodothyronine may have on the concentration of plasma cortisol in the sheep. 3. Thyroid activity was measured by determination of plasma protein bound 125I (PB125I) and total 125I in thyroid vein and mixed venous (jugular) blood. Plasma cortisol and thyroxine concentrations were measured by a competitive protein-binding assay at intervals for up to 5 hr after commencement of the experiment. 4. No evidence of an activation of thyroid secretion was found during cortisol or ACTH infusion, as monitored by thyroid vein PB125I. Similarly there was no evidence of any inhibition of thyroid function, as measured by continued secretion of thyroid hormones into thyroid vein blood. 5. No effect on plasma cortisol concentration due to thyroid hormone treatment was observed. 6. It was concluded that (a) elevated circulating corticosteroids in physiological concentrations have no short-term effects on thyroid activity in the sheep and (b) the short-term alterations in thyroid and adrenal cortical secretion observed during stress in the sheep could not be attributed to direct interaction of elevated thyroid hormone concentrations with adrenal cortical secretion. PMID:170400

  12. Jones index, secret sharing and total quantum dimension

    Science.gov (United States)

    Fiedler, Leander; Naaijkens, Pieter; Osborne, Tobias J.

    2017-02-01

    We study the total quantum dimension in the thermodynamic limit of topologically ordered systems. In particular, using the anyons (or superselection sectors) of such models, we define a secret sharing scheme, storing information invisible to a malicious party, and argue that the total quantum dimension quantifies how well we can perform this task. We then argue that this can be made mathematically rigorous using the index theory of subfactors, originally due to Jones and later extended by Kosaki and Longo. This theory provides us with a ‘relative entropy’ of two von Neumann algebras and a quantum channel, and we argue how these can be used to quantify how much classical information two parties can hide form an adversary. We also review the total quantum dimension in finite systems, in particular how it relates to topological entanglement entropy. It is known that the latter also has an interpretation in terms of secret sharing schemes, although this is shown by completely different methods from ours. Our work provides a different and independent take on this, which at the same time is completely mathematically rigorous. This complementary point of view might be beneficial, for example, when studying the stability of the total quantum dimension when the system is perturbed.

  13. Long-term outcomes of surgery and radiotherapy for secreting and non-secreting pituitary adenoma

    International Nuclear Information System (INIS)

    Kim, Mi Young; Kim, Jin Hee; Oh, Young Kee; Kim, El

    2016-01-01

    To investigate treatment outcome and long term complication after surgery and radiotherapy (RT) for pituitary adenoma. From 1990 to 2009, 73 patients with surgery and RT for pituitary adenoma were analyzed in this study. Median age was 51 years (range, 25 to 71 years). Median tumor size was 3 cm (range, 1 to 5 cm) with suprasellar (n = 21), cavernous sinus extension (n = 14) or both (n = 5). Hormone secreting tumor was diagnosed in 29 patients; 16 patients with prolactin, 12 patients with growth hormone, and 1 patient with adrenocorticotrophic hormone. Impairment of visual acuity or visual field was presented in 33 patients at first diagnosis. Most patients (n = 64) received RT as postoperative adjuvant setting. Median RT dose was 45 Gy (range, 45 to 59.4 Gy). Median follow-up duration was 8 years (range, 3 to 22 years). In secreting tumors, hormone normalization rate was 55% (16 of 29 patients). For 25 patients with evaluable visual field and visual acuity test, 21 patients (84%) showed improvement of visual disturbance after treatment. The 10-year tumor control rate for non-secreting and secreting adenoma was 100% and 58%, respectively (p < 0.001). Progression free survival rate at 10 years was 98%. Only 1 patient experienced endocrinological recurrence. Following surgery, 60% (n = 44) suffered from pituitary function deficit. Late complication associated with RT was only 1 patient, who developed cataract. Surgery and RT are very effective and safe in hormonal and tumor growth control for secreting and non-secreting pituitary adenoma

  14. Long-term outcomes of surgery and radiotherapy for secreting and non-secreting pituitary adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi Young; Kim, Jin Hee; Oh, Young Kee; Kim, El [Dongsan Medical Center, Keimyung University School of Medicine, Daegu (Korea, Republic of)

    2016-06-15

    To investigate treatment outcome and long term complication after surgery and radiotherapy (RT) for pituitary adenoma. From 1990 to 2009, 73 patients with surgery and RT for pituitary adenoma were analyzed in this study. Median age was 51 years (range, 25 to 71 years). Median tumor size was 3 cm (range, 1 to 5 cm) with suprasellar (n = 21), cavernous sinus extension (n = 14) or both (n = 5). Hormone secreting tumor was diagnosed in 29 patients; 16 patients with prolactin, 12 patients with growth hormone, and 1 patient with adrenocorticotrophic hormone. Impairment of visual acuity or visual field was presented in 33 patients at first diagnosis. Most patients (n = 64) received RT as postoperative adjuvant setting. Median RT dose was 45 Gy (range, 45 to 59.4 Gy). Median follow-up duration was 8 years (range, 3 to 22 years). In secreting tumors, hormone normalization rate was 55% (16 of 29 patients). For 25 patients with evaluable visual field and visual acuity test, 21 patients (84%) showed improvement of visual disturbance after treatment. The 10-year tumor control rate for non-secreting and secreting adenoma was 100% and 58%, respectively (p < 0.001). Progression free survival rate at 10 years was 98%. Only 1 patient experienced endocrinological recurrence. Following surgery, 60% (n = 44) suffered from pituitary function deficit. Late complication associated with RT was only 1 patient, who developed cataract. Surgery and RT are very effective and safe in hormonal and tumor growth control for secreting and non-secreting pituitary adenoma.

  15. Biliary cholesterol secretion : More than a simple ABC

    NARCIS (Netherlands)

    Dikkers, Arne; Tietge, Uwe J. F.

    2010-01-01

    Biliary cholesterol secretion is a process important for 2 major disease complexes, atherosclerotic cardiovascular disease and cholesterol gallstone disease With respect to cardiovascular disease, biliary cholesterol secretion is regarded as the final step for the elimination of cholesterol

  16. psycho-social correlates of students' involvement in secret cults

    African Journals Online (AJOL)

    PROF EKWUEME

    as constituting general threat to peace in institutions of higher learning. (Fawole ... involvement in secret cults, and to investigate if peer group do influence students involvement in secret cults. .... be of benefit to students, teachers, parents,.

  17. SECURE VISUAL SECRET SHARING BASED ON DISCRETE WAVELET TRANSFORM

    Directory of Open Access Journals (Sweden)

    S. Jyothi Lekshmi

    2015-08-01

    Full Text Available Visual Cryptography Scheme (VCS is an encryption method to encode secret written materials. This method converts the secret written material into an image. Then encode this secret image into n shadow images called shares. For the recreation of the original secret, all or some selected subsets of shares are needed; individual shares are of no use on their own. The secret image can be recovered simply by selecting some subset of these n shares, makes transparencies of them and stacking on top of each other. Nowadays, the data security has an important role. The shares can be altered by an attacker. So providing security to the shares is important. This paper proposes a method of adding security to cryptographic shares. This method uses two dimensional discrete wavelet transform to hide visual secret shares. Then the hidden secrets are distributed among participants through the internet. All hidden shares are extracted to reconstruct the secret.

  18. A thyrotropin‑secreting macroadenoma with positive growth ...

    African Journals Online (AJOL)

    A thyrotropin‑secreting macroadenoma with positive growth hormone and prolactin immunostaining: A case report and literature review. ... thyroid hormone receptor resistance syndrome. Key words: Inappropriate thyroid stimulating hormone, thyrotropin‑secreting pituitary adenoma, thyroid stimulating hormone adenoma ...

  19. Ranitidine has no influence on tubular creatinine secretion

    NARCIS (Netherlands)

    van den Berg, J. G.; Koopman, M. G.; Arisz, L.

    1996-01-01

    Oral cimetidine competitively inhibits tubular secretion of creatinine. We investigated the potential of oral ranitidine, a comparable H2-receptor antagonist, to block tubular creatinine secretion. In 10 healthy subjects, clearances of inulin and endogenous creatinine were simultaneously measured

  20. Molecular Mechanisms of Insulin Secretion and Insulin Action.

    Science.gov (United States)

    Flatt, Peter R.; Bailey, Clifford J.

    1991-01-01

    Information and current ideas on the factors regulating insulin secretion, the mechanisms underlying the secretion and biological actions of insulin, and the main characteristics of diabetes mellitus are presented. (Author)