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Sample records for ai-2 based qs

  1. Synthesis of QS-21-Based Immunoadjuvants

    PubMed Central

    Dai, Qipu; Thogaripally, Punith; Zhang, Ping; Michalek, Suzanne M.

    2014-01-01

    Three structurally defined QS-21-based immune adjuvant candidates (2a-2c) have been synthesized. Application of the two-stage activation glycosylation approach utilizing allyl glycoside building blocks improved the synthetic accessibility of the new adjuvants. The efficient synthesis and establishment of the stand-alone adjuvanticity of the examined synthetic adjuvant (2b) open the door to the pursuit of a new series of structurally defined QS-saponin based synthetic adjuvants. PMID:24147602

  2. Revisiting AI-2 quorum sensing inhibitors: direct comparison of alkyl-DPD analogues and a natural product fimbrolide.

    PubMed

    Lowery, Colin A; Abe, Takumi; Park, Junguk; Eubanks, Lisa M; Sawada, Daisuke; Kaufmann, Gunnar F; Janda, Kim D

    2009-11-04

    Quorum sensing (QS) systems have been discovered in a wide variety of bacteria, and mediate both intra- and interspecies communication. The AI-2-based QS system represents the most studied of these proposed interspecies systems and has been shown to regulate diverse functions such as bioluminescence, expression of virulence factors, and biofilm formation. As such, the development of modulatory compounds, both agonists and antagonists, is of great interest for the study of unknown AI-2-based QS systems and the potential treatment of bacterial infections. The fimbrolide class of natural products has exhibited excellent inhibitory activity against AI-2-based QS and as such may be considered the "gold standard" of AI-2 inhibitors. Thus, we sought to include a fimbrolide as a control compound for our recently developed alkyl-DPD panel of AI-2 modulators. Herein, we present a revised synthesis of a commonly studied fimbrolide as well as a direct comparison between the fimbrolide and alkyl-DPD analogues. We demonstrate that our alkyl-DPD analogues are more potent inhibitors of QS in both Vibrio harveyi and Salmonella typhimurium, the two organisms with defined AI-2 QS systems, and in doing so call into question the widely accepted use of fimbrolide-derived compounds as the "gold standard" of AI-2 inhibition.

  3. Integration of AI-2 Based Cell-Cell Signaling with Metabolic Cues in Escherichia coli

    PubMed Central

    Mitra, Arindam; Herren, Christopher D.; Patel, Isha R.; Coleman, Adam; Mukhopadhyay, Suman

    2016-01-01

    The quorum sensing molecule Autoinducer-2 (AI-2) is generated as a byproduct of activated methyl cycle by the action of LuxS in Escherichia coli. AI-2 is synthesized, released and later internalized in a cell-density dependent manner. Here, by mutational analysis of the genes, uvrY and csrA, we describe a regulatory circuit of accumulation and uptake of AI-2. We constructed a single-copy chromosomal luxS-lacZ fusion in a luxS + merodiploid strain and evaluated its relative expression in uvrY and csrA mutants. At the entry of stationary phase, the expression of the fusion and AI-2 accumulation was positively regulated by uvrY and negatively regulated by csrA respectively. A deletion of csrA altered message stability of the luxS transcript and CsrA protein exhibited weak binding to 5’ luxS regulatory region. DNA protein interaction and chromatin immunoprecipitation analysis confirmed direct interaction of UvrY with the luxS promoter. Additionally, reduced expression of the fusion in hfq deletion mutant suggested involvement of small RNA interactions in luxS regulation. In contrast, the expression of lsrA operon involved in AI-2 uptake, is negatively regulated by uvrY and positively by csrA in a cell-density dependent manner. The dual role of csrA in AI-2 synthesis and uptake suggested a regulatory crosstalk of cell signaling with carbon regulation in Escherichia coli. We found that the cAMP-CRP mediated catabolite repression of luxS expression was uvrY dependent. This study suggests that luxS expression is complex and regulated at the level of transcription and translation. The multifactorial regulation supports the notion that cell-cell communication requires interaction and integration of multiple metabolic signals. PMID:27362507

  4. Recent progresses on AI-2 bacterial quorum sensing inhibitors.

    PubMed

    Zhu, Peng; Li, Minyong

    2012-01-01

    Quorum sensing (QS) is a communication procedure that predominates gene expression in response to cell density and fluctuations in the neighboring environment as a result of discerning molecules termed autoinducers (AIs). It has been embroiled that QS can govern bacterial behaviors such as the secretion of virulence factors, biofilm formation, bioluminescence production, conjugation, sporulation and swarming motility. Autoinducer 2 (AI-2), a QS signaling molecule brought up to be involved in interspecies communication, exists in both gram-negative and -positive bacteria. Therefore, novel approaches to interrupt AI-2 quorum sensing are being recognized as next generation antimicrobials. In the present review article, we summarized recent progresses on AI-2 bacterial quorum sensing inhibitors and discussed their potential as the antibacterial agents.

  5. Structure-based discovery and experimental verification of novel AI-2 quorum sensing inhibitors against Vibrio harveyi.

    PubMed

    Li, Minyong; Ni, Nanting; Chou, Han-Ting; Lu, Chung-Dar; Tai, Phang C; Wang, Binghe

    2008-08-01

    Quorum sensing has been implicated in the control of pathologically relevant bacterial behavior such as secretion of virulence factors, biofilm formation, sporulation, and swarming motility. The AI-2 quorum sensing pathway is found in both gram-positive and gram-negative bacteria. Therefore, antagonizing AI-2 quorum sensing is a possible approach to modifying bacterial behaviour. However, efforts in developing inhibitors of AI-2-mediated quorum sensing are especially lacking. High-throughput virtual screening using the V. harveyi LuxP crystal structure identified two compounds that were found to antagonize AI-2-mediated quorum sensing in V. harveyi without cytotoxicity. The sulfone functionality of these inhibitors was identified as critical to their ability to mimic the natural ligand in their interactions with Arg 215 and Arg 310 of the active site.

  6. AI-2 quorum-sensing inhibitors affect the starvation response and reduce virulence in several Vibrio species, most likely by interfering with LuxPQ.

    PubMed

    Brackman, Gilles; Celen, Shari; Baruah, Kartik; Bossier, Peter; Van Calenbergh, Serge; Nelis, Hans J; Coenye, Tom

    2009-12-01

    The increase of disease outbreaks caused by Vibrio species in aquatic organisms as well as in humans, together with the emergence of antibiotic resistance in Vibrio species, has led to a growing interest in alternative disease control measures. Quorum sensing (QS) is a mechanism for regulating microbial gene expression in a cell density-dependent way. While there is good evidence for the involvement of auto-inducer 2 (AI-2)-based interspecies QS in the control of virulence in multiple Vibrio species, only few inhibitors of this system are known. From the screening of a small panel of nucleoside analogues for their ability to disturb AI-2-based QS, an adenosine derivative with a p-methoxyphenylpropionamide moiety at C-3' emerged as a promising hit. Its mechanism of inhibition was elucidated by measuring the effect on bioluminescence in a series of Vibrio harveyi AI-2 QS mutants. Our results indicate that this compound, as well as a truncated analogue lacking the adenine base, block AI-2-based QS without interfering with bacterial growth. The active compounds affected neither the bioluminescence system as such nor the production of AI-2, but most likely interfered with the signal transduction pathway at the level of LuxPQ in V. harveyi. The most active nucleoside analogue (designated LMC-21) was found to reduce the Vibrio species starvation response, to affect biofilm formation in Vibrio anguillarum, Vibrio vulnificus and Vibrio cholerae, to reduce pigment and protease production in V. anguillarum, and to protect gnotobiotic Artemia from V. harveyi-induced mortality.

  7. A Parametric Evaluation of Qs-Vs Relationships Used in Physics-Based Ground-Motion Earthquake Simulation

    NASA Astrophysics Data System (ADS)

    Khoshnevis, N.; Taborda, R.

    2015-12-01

    The appropriate representation of attenuation effects due to internal friction in the propagating media is an important factor in earthquake ground motion simulation. Inaccuracies in this regard may result in incorrect estimations of the amplification and duration of seismic waves. This is particularly relevant in regions with high dissipative properties. In physics-based simulations, the attenuation of seismic waves is typically introduced using viscoelastic models. Internally, the properties of these models are set based on the quality factor Q. In turn, the values of Q are set based on the seismic velocities Qp and Qs. In the case of shear waves, for instance, Qs is usually defined based on empirical rules that depend on the shear wave velocity, Vs. Typical Qs-Vs relationships are (piecewise) linear or polynomial functions. Several Qs-Vs relationships exist in the literature. There is, however, no consensus about the most appropriate choice. In this study we explore the behavior and effects of different Qs-Vs relationships in ground motion simulations of historical earthquakes. We propose a flexible Qs-Vs relationship and perform a parametric on different forms of the proposed Qs-Vs rule. The different relationship parameters are tested through the validation of synthetics with data from historical events, and through comparisons with intensity measures such as those used in empirical ground motion prediction equations. Our results suggest that there exist a preferred set of parameters for the choice of Qs-Vs relationships, and we provide insights on the selection process.

  8. Development of Improved Vaccine Adjuvants Based on the Saponin Natural Product QS-21 through Chemical Synthesis.

    PubMed

    Fernández-Tejada, Alberto; Tan, Derek S; Gin, David Y

    2016-09-20

    Vaccines based on molecular subunit antigens are increasingly being investigated due to their improved safety and more precise targeting compared to classical whole-pathogen vaccines. However, subunit vaccines are inherently less immunogenic; thus, coadministration of an adjuvant to increase the immunogenicity of the antigen is often necessary to elicit a potent immune response. QS-21, an immunostimulatory saponin natural product, has been used as an adjuvant in conjunction with various vaccines in numerous clinical trials, but suffers from several inherent liabilities, including scarcity, chemical instability, and dose-limiting toxicity. Moreover, little is known about its mechanism of action. Over a decade-long effort, beginning at the University of Illinois at Urbana-Champaign and continuing at the Memorial Sloan Kettering Cancer Center (MSKCC), the group of Prof. David Y. Gin accomplished the total synthesis of QS-21 and developed a practical semisynthetic approach to novel variants that overcome the liabilities of the natural product. First, semisynthetic QS-21 variants were designed with stable amide linkages in the acyl chain domain that exhibited comparable in vivo adjuvant activity and lower toxicity than the natural product. Further modifications in the acyl chain domain and truncation of the linear tetrasaccharide domain led to identification of a trisaccharide variant with a simple carboxylic acid side chain that retained potent adjuvant activity, albeit with reemergence of toxicity. Conversely, an acyl chain analogue terminating in a free amine was inactive but enabled chemoselective functionalization with radiolabeled and fluorescent tags, yielding adjuvant-active saponin probes that, unlike inactive congeners, accumulated in the lymph nodes in vaccinated mice and internalized into dendritic cells. Subtle variations in length, stereochemistry, and conformational flexibility around the central glycosidic linkage provided QS-21 variants with adjuvant

  9. Development of Improved Vaccine Adjuvants Based on the Saponin Natural Product QS-21 through Chemical Synthesis

    PubMed Central

    2016-01-01

    Conspectus Vaccines based on molecular subunit antigens are increasingly being investigated due to their improved safety and more precise targeting compared to classical whole-pathogen vaccines. However, subunit vaccines are inherently less immunogenic; thus, coadministration of an adjuvant to increase the immunogenicity of the antigen is often necessary to elicit a potent immune response. QS-21, an immunostimulatory saponin natural product, has been used as an adjuvant in conjunction with various vaccines in numerous clinical trials, but suffers from several inherent liabilities, including scarcity, chemical instability, and dose-limiting toxicity. Moreover, little is known about its mechanism of action. Over a decade-long effort, beginning at the University of Illinois at Urbana-Champaign and continuing at the Memorial Sloan Kettering Cancer Center (MSKCC), the group of Prof. David Y. Gin accomplished the total synthesis of QS-21 and developed a practical semisynthetic approach to novel variants that overcome the liabilities of the natural product. First, semisynthetic QS-21 variants were designed with stable amide linkages in the acyl chain domain that exhibited comparable in vivo adjuvant activity and lower toxicity than the natural product. Further modifications in the acyl chain domain and truncation of the linear tetrasaccharide domain led to identification of a trisaccharide variant with a simple carboxylic acid side chain that retained potent adjuvant activity, albeit with reemergence of toxicity. Conversely, an acyl chain analogue terminating in a free amine was inactive but enabled chemoselective functionalization with radiolabeled and fluorescent tags, yielding adjuvant-active saponin probes that, unlike inactive congeners, accumulated in the lymph nodes in vaccinated mice and internalized into dendritic cells. Subtle variations in length, stereochemistry, and conformational flexibility around the central glycosidic linkage provided QS-21 variants with

  10. Development of a minimal saponin vaccine adjuvant based on QS-21

    NASA Astrophysics Data System (ADS)

    Fernández-Tejada, Alberto; Chea, Eric K.; George, Constantine; Pillarsetty, Nagavarakishore; Gardner, Jeffrey R.; Livingston, Philip O.; Ragupathi, Govind; Lewis, Jason S.; Tan, Derek S.; Gin, David Y.

    2014-07-01

    Adjuvants are materials added to vaccines to enhance the immunological response to an antigen. QS-21 is a natural product adjuvant under investigation in numerous vaccine clinical trials, but its use is constrained by scarcity, toxicity, instability and an enigmatic molecular mechanism of action. Herein we describe the development of a minimal QS-21 analogue that decouples adjuvant activity from toxicity and provides a powerful platform for mechanistic investigations. We found that the entire branched trisaccharide domain of QS-21 is dispensable for adjuvant activity and that the C4-aldehyde substituent, previously proposed to bind covalently to an unknown cellular target, is also not required. Biodistribution studies revealed that active adjuvants were retained preferentially at the injection site and the nearest draining lymph nodes compared with the attenuated variants. Overall, these studies have yielded critical insights into saponin structure-function relationships, provided practical synthetic access to non-toxic adjuvants, and established a platform for detailed mechanistic studies.

  11. Structure-Activity Relationship of Cinnamaldehyde Analogs as Inhibitors of AI-2 Based Quorum Sensing and Their Effect on Virulence of Vibrio spp

    PubMed Central

    Brackman, Gilles; Celen, Shari; Hillaert, Ulrik; Van Calenbergh, Serge; Cos, Paul; Maes, Louis; Nelis, Hans J.; Coenye, Tom

    2011-01-01

    Background Many bacteria, including Vibrio spp., regulate virulence gene expression in a cell-density dependent way through a communication process termed quorum sensing (QS). Hence, interfering with QS could be a valuable novel antipathogenic strategy. Cinnamaldehyde has previously been shown to inhibit QS-regulated virulence by decreasing the DNA-binding ability of the QS response regulator LuxR. However, little is known about the structure-activity relationship of cinnamaldehyde analogs. Methodology/Principal Findings By evaluating the QS inhibitory activity of a series of cinnamaldehyde analogs, structural elements critical for autoinducer-2 QS inhibition were identified. These include an α,β unsaturated acyl group capable of reacting as Michael acceptor connected to a hydrophobic moiety and a partially negative charge. The most active cinnamaldehyde analogs were found to affect the starvation response, biofilm formation, pigment production and protease production in Vibrio spp in vitro, while exhibiting low cytotoxicity. In addition, these compounds significantly increased the survival of the nematode Caenorhabditis elegans infected with Vibrio anguillarum, Vibrio harveyi and Vibrio vulnificus. Conclusions/Significance Several new and more active cinnamaldehyde analogs were discovered and they were shown to affect Vibrio spp. virulence factor production in vitro and in vivo. Although ligands for LuxR have not been identified so far, the nature of different cinnamaldehyde analogs and their effect on the DNA binding ability of LuxR suggest that these compounds act as LuxR-ligands. PMID:21249192

  12. AI-2 of Aggregatibacter actinomycetemcomitans inhibits Candida albicans biofilm formation.

    PubMed

    Bachtiar, Endang W; Bachtiar, Boy M; Jarosz, Lucja M; Amir, Lisa R; Sunarto, Hari; Ganin, Hadas; Meijler, Michael M; Krom, Bastiaan P

    2014-01-01

    Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (AI-2), synthesized by LuxS, that plays an important role in expression of virulence factors, in intra- but also in interspecies communication. The aim of this study was to investigate the role of AI-2 based signaling in the interactions between C. albicans and A. actinomycetemcomitans. A. actinomycetemcomitans adhered to C. albicans and inhibited biofilm formation by means of a molecule that was secreted during growth. C. albicans biofilm formation increased significantly when co-cultured with A. actinomycetemcomitans luxS, lacking AI-2 production. Addition of wild-type-derived spent medium or synthetic AI-2 to spent medium of the luxS strain, restored inhibition of C. albicans biofilm formation to wild-type levels. Addition of synthetic AI-2 significantly inhibited hypha formation of C. albicans possibly explaining the inhibition of biofilm formation. AI-2 of A. actinomycetemcomitans is synthesized by LuxS, accumulates during growth and inhibits C. albicans hypha- and biofilm formation. Identifying the molecular mechanisms underlying the interaction between bacteria and fungi may provide important insight into the balance within complex oral microbial communities.

  13. Crystal structures of the LsrR proteins complexed with phospho-AI-2 and two signal-interrupting analogues reveal distinct mechanisms for ligand recognition.

    PubMed

    Ha, Jung-Hye; Eo, Yumi; Grishaev, Alexander; Guo, Min; Smith, Jacqueline A I; Sintim, Herman O; Kim, Eun-Hee; Cheong, Hae-Kap; Bentley, William E; Ryu, Kyoung-Seok

    2013-10-16

    Quorum sensing (QS) is a cell-to-cell communication system responsible for a variety of bacterial phenotypes including virulence and biofilm formation. QS is mediated by small molecules, autoinducers (AIs), including AI-2 that is secreted by both Gram-positive and -negative microbes. LsrR is a key transcriptional regulator that governs the varied downstream processes by perceiving AI-2 signal, but its activation via autoinducer-binding remains poorly understood. Here, we provide detailed regulatory mechanism of LsrR from the crystal structures in complexes with the native signal (phospho-AI-2, D5P) and two quorum quenching antagonists (ribose-5-phosphate, R5P; phospho-isobutyl-AI-2, D8P). Interestingly, the bound D5P and D8P molecules are not the diketone forms but rather hydrated, and the hydrated moiety forms important H-bonds with the carboxylate of D243. The D5P-binding flipped out F124 of the binding pocket, and resulted in the disruption of the dimeric interface-1 by unfolding the α7 segment. However, the same movement of F124 by the D8P'-binding did not cause the unfolding of the α7 segment. Although the LsrR-binding affinity of R5P (Kd, ∼1 mM) is much lower than that of D5P and D8P (∼2.0 and ∼0.5 μM), the α-anomeric R5P molecule fits into the binding pocket without any structural perturbation, and thus stabilizes the LsrR tetramer. The binding of D5P, not D8P and R5P, disrupted the tetrameric structure and thus is able to activate LsrR. The detailed structural and mechanistic insights from this study could be useful for facilitating design of new antivirulence and antibiofilm agents based on LsrR.

  14. Detection of autoinducer (AI-2)-like activity in food samples.

    PubMed

    Sivakumar, Kirthiram K; Jesudhasan, Palmy R; Pillai, Suresh D

    2011-01-01

    The contamination, survival, and possible foodborne disease outbreaks are major issues confronting the food industry. However, from a microbial perspective, any food whether natural or processed is just another environmental niche that is available for colonization. Quorum sensing or cell-cell communication is a process by which microorganisms are thought to communicate with each other using a variety of small molecules termed autoinducers. The autoinducer AI-2 is thought to be a universal signaling molecule due to its ability to modulate the gene expression of a number of different bacterial species and genera. Pathogens such as Pseudomonas aeruginosa, Aeromonas hydrophila, Vibrio anguillarum, Streptococcus sp., and Burkholderia cepacia form biofilms on a variety of man-made and natural surfaces using cell-cell mechanisms. It is important to detect and study autoinducers and their activities in foods, since a better understanding of these molecules in food and food ingredients may help in designing new approaches to thwart microbial persistence and biofilm formation. The autoinducer AI-2 is thought to be involved in microbial attachment and biofilm formation leading to food spoilage. To better understand microbial cell-cell signaling in foods especially as it relates to pathogen persistence, biofilm formation, and food spoilage, methods to process, extract, and purify autoinducer molecules need to be developed. This chapter details methods to process food samples to obtain cell-free supernatants (CFS), which could subsequently be tested for the presence of AI-2 or "AI-2-like activity" in the extracted CFS using autoinducer bioassays. Additionally, the method of synthesizing AI-2 in the laboratory is also provided. The methods that are presented in this chapter are based on previously published research articles from the authors' laboratory.

  15. Highly Effective Inhibition of Biofilm Formation by the First Metagenome-Derived AI-2 Quenching Enzyme

    PubMed Central

    Weiland-Bräuer, Nancy; Kisch, Martin J.; Pinnow, Nicole; Liese, Andreas; Schmitz, Ruth A.

    2016-01-01

    Bacterial cell–cell communication (quorum sensing, QS) represents a fundamental process crucial for biofilm formation, pathogenicity, and virulence allowing coordinated, concerted actions of bacteria depending on their cell density. With the widespread appearance of antibiotic-resistance of biofilms, there is an increasing need for novel strategies to control harmful biofilms. One attractive and most likely effective approach is to target bacterial communication systems for novel drug design in biotechnological and medical applications. In this study, metagenomic large-insert libraries were constructed and screened for QS interfering activities (quorum quenching, QQ) using recently established reporter strains. Overall, 142 out of 46,400 metagenomic clones were identified to interfere with acyl-homoserine lactones (AHLs), 13 with autoinducer-2 (AI-2). Five cosmid clones with highest simultaneous interfering activities were further analyzed and the respective open reading frames conferring QQ activities identified. Those showed homologies to bacterial oxidoreductases, proteases, amidases and aminotransferases. Evaluating the ability of the respective purified QQ-proteins to prevent biofilm formation of several model systems demonstrated highest inhibitory effects of QQ-2 using the crystal violet biofilm assay. This was confirmed by heterologous expression of the respective QQ proteins in Klebsiella oxytoca M5a1 and monitoring biofilm formation in a continuous flow cell system. Moreover, QQ-2 chemically immobilized to the glass surface of the flow cell effectively inhibited biofilm formation of K. oxytoca as well as clinical K. pneumoniae isolates derived from patients with urinary tract infections. Indications were obtained by molecular and biochemical characterizations that QQ-2 represents an oxidoreductase most likely reducing the signaling molecules AHL and AI-2 to QS-inactive hydroxy-derivatives. Overall, we propose that the identified novel QQ-2 protein

  16. Probing autoinducer-2 based quorum sensing: the biological consequences of molecules unable to traverse equilibrium states.

    PubMed

    Tsuchikama, Kyoji; Lowery, Colin A; Janda, Kim D

    2011-09-02

    Bacteria have developed a cell-to-cell communication system, termed quorum sensing (QS), which allows for the population-dependent coordination of their behavior via the exchange of chemical signals. Autoinducer-2 (AI-2), a class of QS signals derived from 4,5-dihydroxy-2,3-pentandione (DPD), has been revealed as a universal signaling molecule in a variety of bacterial species. In spite of considerable interest, the study of putative AI-2 based QS systems remains a challenging topic in part due to the rapid interconversion between the linear and cyclic forms of DPD. Herein, we report the design and development of efficient syntheses of carbocyclic analogues of DPD, which are locked in the cyclic form. The synthetic analogues were evaluated for the modulation of AI-2-based QS in Vibrio harveyi and Salmonella typhimurium. No agonists were uncovered in either V. harveyi or S. typhimurium assay, whereas weak to moderate antagonists were found against V. harveyi. On the basis of NMR analyses and DFT calculations, the heterocyclic oxygen atom within DPD appears necessary to promote hydration at the C3 position of cyclic DPD to afford the active tetrahydroxy species. These results also shed light on the interaction between the heterocyclic oxygen atom and receptor proteins as well as the importance of the linear form and dynamic equilibrium of DPD as crucial requirements for activation of AI-2 based QS circuits.

  17. Fatty acid modulation of autoinducer (AI-2) influenced growth and macrophage invasion by Salmonella Typhimurium.

    PubMed

    Widmer, Kenneth W; Jesudhasan, Palmy; Pillai, Suresh D

    2012-03-01

    Autoinducer-2 (AI-2) is a small molecule that is involved in bacterial cell-to-cell signaling whose precursor formation is mediated by luxS. A luxS mutant of Salmonella Typhimurium PJ002 (ΔluxS) was grown in glucose-containing M-9 minimal medium supplemented with varying concentrations (1×, 10×, and 100×) of long-chain fatty acids (linoleic acid, oleic acid, palmitic acid, and stearic acid) to study the influence of fatty acids on growth rate and macrophage invasion. Additionally, in vitro synthesized AI-2 was added to this medium to identify the influence of AI-2 on S. Typhimurium PJ002 (ΔluxS) growth rate and macrophage invasion. The growth rate constant (k) for each experimental treatment was determined based on OD₆₀₀ values recorded during 12 h of incubation. There was a significant (p=0.01) increase in the growth rate of S. Typhimurium PJ002 (ΔluxS) in the presence of AI-2 when compared to the phosphate-buffered saline (PBS) control. However, fatty acids either singly or in a mixture were unable to influence AI-2's effect on growth rate. The presence of AI-2 significantly (p=0.02) decreased the invasiveness of S. Typhimurium PJ002 (ΔluxS) towards the murine macrophage cell line, RAW 264.7. However, the fatty acid mixture was able to reverse this reduction and restore invasiveness to background levels. These results suggest that, while AI-2 may enhance the growth rate and reduce macrophage invasion by the luxS mutant S. Typhimurium PJ002 (ΔluxS), fatty acids may influence the virulence in S. Typhimurium (PJ002) by modulating AI-2 activity.

  18. The metabolic flux regulation of Klebsiella pneumoniae based on quorum sensing system

    PubMed Central

    Sun, Shujing; Zhang, Haiyang; Lu, Shuyi; Lai, Chunfen; Liu, Huijun; Zhu, Hu

    2016-01-01

    Quorum-sensing (QS) systems exist universally in bacteria to regulate multiple biological functions. Klebsiella pneumoniae, an industrially important bacterium that produces bio-based chemicals such as 2,3-butanediol and acetoin, can secrete a furanosyl borate diester (AI-2) as the signalling molecule mediating a QS system, which plays a key regulatory role in the biosynthesis of secondary metabolites. In this study, the molecular regulation and metabolic functions of a QS system in K. pneumoniae were investigated. The results showed that after the disruption of AI-2-mediated QS by the knockout of luxS, the production of acetoin, ethanol and acetic acid were relatively lower in the K. pneumoniae mutant than in the wild type bacteria. However, 2,3-butanediol production was increased by 23.8% and reached 54.93 g/L. The observed enhancement may be attributed to the improvement of the catalytic activity of 2,3-butanediol dehydrogenase (BDH) in transforming acetoin to 2,3-butanediol. This possibility is consistent with the RT-PCR-verified increase in the transcriptional level of budC, which encodes BDH. These results also demonstrated that the physiological metabolism of K. pneumoniae was adversely affected by a QS system. This effect was reversed through the addition of synthetic AI-2. This study provides the basis for a QS-modulated metabolic engineering study of K. pneumoniae. PMID:27924940

  19. Furvina inhibits the 3-oxo-C12-HSL-based quorum sensing system of Pseudomonas aeruginosa and QS-dependent phenotypes.

    PubMed

    Borges, Anabela; Sousa, Pedro; Gaspar, Alexandra; Vilar, Santiago; Borges, Fernanda; Simões, Manuel

    2017-02-01

    Disruption of cell-cell communication or quorum sensing (QS) is considered a stimulating approach for reducing bacterial pathogenicity and resistance. Although several QS inhibitors (QSIs) have been discovered so far their clinical use remains distant. This problem can be circumvented by searching for QSI among drugs already approved for the treatment of different diseases. In this context, antibiotics have earned special attention. Whereas at high concentrations antibiotics exert a killing effect, at lower concentrations they may act as signaling molecules and as such can modulate gene expression. In this study, the antibiotic furvina was shown to be able to cause inhibition of the 3-oxo-C12-HSL-dependent QS system of Pseudomonas aeruginosa. Furvina interacts with the LasI/LasR system. The data were validated by modeling studies. Furvina can also reduce biofilm formation and decrease the production of QS-controlled virulence factors.

  20. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  1. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  2. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  3. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  4. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  5. QS-21: a potent vaccine adjuvant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    QS-21 is an potent adjuvant derived from the bark of a Chilean tree, Quillaja saponaria. One of the advantages of this adjuvant is that it promotes a balanced humoral and cell-mediaed immune response and can be widely applicable to a variety of vaccines. This adjuvant has used for some veterinary va...

  6. Regulation of Yersina pestis Virulence by AI-2 Mediated Quorum Sensing

    SciTech Connect

    Segelke, B; Hok, S; Lao, V; Corzett, M; Garcia, E

    2010-03-29

    The proposed research was motivated by an interest in understanding Y. pestis virulence mechanisms and bacteria cell-cell communication. It is expected that a greater understanding of virulence mechanisms will ultimately lead to biothreat countermeasures and novel therapeutics. Y. pestis is the etiological agent of plague, the most devastating disease in human history. Y. pestis infection has a high mortality rate and a short incubation before mortality. There is no widely available and effective vaccine for Y. pestis and multi-drug resistant strains are emerging. Y. pestis is a recognized biothreat agent based on the wide distribution of the bacteria in research laboratories around the world and on the knowledge that methods exist to produce and aerosolize large amounts of bacteria. We hypothesized that cell-cell communication via signaling molecules, or quorum sensing, by Y. pestis is important for the regulation of virulence factor gene expression during host invasion, though a causative link had never been established. Quorum sensing is a mode of intercellular communication which enables orchestration of gene expression for many bacteria as a function of population density and available evidence suggests there may be a link between quorum sensing and regulation of Y. pesits virulence. Several pathogenic bacteria have been shown to regulate expression of virulence factor genes, including genes encoding type III secretion, via quorum sensing. The Y. pestis genome encodes several cell-cell signaling pathways and the interaction of at least three of these are thought to be involved in one or more modes of host invasion. Furthermore, Y. pestis gene expression array studies carried out at LLNL have established a correlation between expression of known virulence factors and genes involved in processing of the AI-2 quorum sensing signal. This was a basic research project that was intended to provide new insights into bacterial intercellular communication and how it is

  7. Autoinducer AI-2 is involved in regulating a variety of cellular processes in Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    LuxS/AI-2 mediated cell signaling is a known strategy that modulates a variety of bacterial processes in prokaryotes. Salmonella Typhimurium is known to possess LuxS/AI-2 mediated cell signaling. Until now, the Lsr- ABC transporter system (LuxS- regulated) is the only known process controlled by t...

  8. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... stationary floating crab processor. (3) PQS issued to Blue Dutch, LLC. (i) Pursuant to Public Law 109-241... crab QS fishery. (ii) PQS units issued to Blue Dutch, LLC, under paragraph (e)(3)(i) of this section... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Crab Quota Share (QS), Processor QS...

  9. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on: (1... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Initial Issuance of Crab QS by Crab...

  10. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on: (1... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial Issuance of Crab QS by Crab...

  11. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on:(1... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Initial Issuance of Crab QS by Crab...

  12. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on:(1... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Initial Issuance of Crab QS by Crab...

  13. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on: (1... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Initial Issuance of Crab QS by Crab...

  14. Thiophenone Attenuates Enteropathogenic Escherichia coli O103:H2 Virulence by Interfering with AI-2 Signaling

    PubMed Central

    Valen Rukke, Håkon; Benneche, Tore; Aamdal Scheie, Anne

    2016-01-01

    Interference with bacterial quorum sensing communication provides an anti-virulence strategy to control pathogenic bacteria. Here, using the Enteropathogenic E. coli (EPEC) O103:H2, we showed for the first time that thiophenone TF101 reduced expression of lsrB; the gene encoding the AI-2 receptor. Combined results of transcriptional and phenotypic analyses suggested that TF101 interfere with AI-2 signalling, possibly by competing with AI-2 for binding to LsrB. This is supported by in silico docking prediction of thiophenone TF101 in the LsrB pocket. Transcriptional analyses furthermore showed that thiophenone TF101 interfered with expression of the virulence genes eae and fimH. In addition, TF101 reduced AI-2 induced E. coli adhesion to colorectal adenocarcinoma cells. TF101, on the other hand, did not affect epinephrine or norepinephrine enhanced E. coli adhesion. Overall, our results showed that thiophenone TF101 interfered with virulence expression in E. coli O103:H2, suggestedly by interfering with AI-2 mediated quorum sensing. We thus conclude that thiophenone TF101 might represent a promising future anti-virulence agent in the fight against pathogenic E. coli. PMID:27309855

  15. Development of a robust mapping between AIS 2+ and ICD-9 injury codes.

    PubMed

    Barnard, Ryan T; Loftis, Kathryn L; Martin, R Shayn; Stitzel, Joel D

    2013-03-01

    Motor vehicle crashes result in millions of injuries and thousands of deaths each year in the United States. While most crash research datasets use Abbreviated Injury Scale (AIS) codes to identify injuries, most hospital datasets use the International Classification of Diseases, version 9 (ICD-9) codes. The objective of this research was to establish a one-to-one mapping between AIS and ICD-9 codes for use with motor vehicle crash injury research. This paper presents results from investigating different mapping approaches using the most common AIS 2+ injuries from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). The mapping approaches were generated from the National Trauma Data Bank (NTDB) (428,637 code pairs), ICDMAP (2500 code pairs), and the Crash Injury Research and Engineering Network (CIREN) (4125 code pairs). Each approach may pair given AIS code with more than one ICD-9 code (mean number of pairs per AIS code: NTDB=211, ICDMAP=7, CIREN=5), and some of the potential pairs are unrelated. The mappings were evaluated using two comparative metrics coupled with qualitative inspection by an expert physician. Based on the number of false mappings and correct pairs, the best mapping was derived from CIREN. AIS and ICD-9 codes in CIREN are both manually coded, leading to more proper mappings between the two. Using the mapping presented herein, data from crash and hospital datasets can be used together to better understand and prevent motor vehicle crash injuries in the future.

  16. Measuring near infrared spectral reflectance changes from water stressed conifer stands with AIS-2

    NASA Technical Reports Server (NTRS)

    Riggs, George; Running, Steven W.

    1987-01-01

    Airborne Imaging Spectrometer-2 (AIS-2) data was acquired over two paired conifer stands for the purpose of detecting differences in spectral reflectance between stressed and natural canopies. Water stress was induced in a stand of Norway spruce and white pine by severing the sapwood near the ground. Water stress during the AIS flights was evaluated through shoot water potential and relative water content measurements. Preliminary analysis with raw AIS-2 data using SPAM indicates that there were small, inconsistent differences in absolute spectral reflectance in the near infrared 0.97 to 1.3 micron between the stressed and natural canopies.

  17. Gene regulation of Salmonella enterica serovar Typhimurium as influenced by LuxS/AI-2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quorum sensing is mediated by small signaling molecules, autoinducer molecules. The luxS gene which is conserved in several Gram-positive and Gram-negative bacteria is involved in the synthesis of the autoinducer molecule-2 (AI-2). Genes controlled by luxS in S. Typhimurium were identified using mic...

  18. Processing the Interspecies Quorum-sensing Signal Autoinducer-2 (AI-2)

    SciTech Connect

    J Marques; P Lamosa; C Russell; R Ventura; C Maycock; M Semmelhack; S Miller; K Xavier

    2011-12-31

    The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsible for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior.

  19. Processing the Interspecies Quorum-sensing Signal Autoinducer-2 (AI-2)

    PubMed Central

    Marques, João C.; Lamosa, Pedro; Russell, Caitlin; Ventura, Rita; Maycock, Christopher; Semmelhack, Martin F.; Miller, Stephen T.; Xavier, Karina B.

    2011-01-01

    The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsible for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior. PMID:21454635

  20. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... the Internet or requested from the Regional Administrator. (ii) An application for crab QS or PQS...

  1. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... the Internet or requested from the Regional Administrator. (ii) An application for crab QS or PQS...

  2. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... the Internet or requested from the Regional Administrator. (ii) An application for crab QS or PQS...

  3. 50 CFR 680.40 - Crab Quota Share (QS), Processor QS (PQS), Individual Fishing Quota (IFQ), and Individual...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., education, exploratory, or experimental permit, or under the Western Alaska CDQ Program. (iv) Documentation... the Internet or requested from the Regional Administrator. (ii) An application for crab QS or PQS...

  4. QS-21 Adjuvant: Laboratory-Scale Purification Method and Formulation Into Liposomes.

    PubMed

    Brunner, Livia; Barnier-Quer, Christophe; Collin, Nicolas

    2017-01-01

    QS-21, a saponin extracted from the tree Quillaja saponaria Molina, is a vaccine adjuvant which has been shown to elicit robust antibody and cell-mediated immune responses in a variety of preclinical and clinical studies [1]. Its purification from the natural source is a lengthy and difficult process. The commercially available saponin mixture Quil-A(®) is a fraction of the bark extract containing a variety of saponins, including QS-21. In order to facilitate access to QS-21 at laboratory-scale amounts, we propose here a method of purification of QS-21 starting from Quil-A(®). In addition, we describe a protocol to appropriately formulate QS-21 into cholesterol-containing, neutral liposomes which are known to decrease QS-21's hemolytic activity while retaining the adjuvant effect. Methods for the physicochemical characterization of purified QS-21 and of the QS-21/liposome formulations are also described.

  5. AI-2/LuxS is involved in increased biofilm formation by Streptococcus intermedius in the presence of antibiotics.

    PubMed

    Ahmed, Nibras A; Petersen, Fernanda C; Scheie, Anne A

    2009-10-01

    Bacteria utilize quorum-sensing communication to organize their behavior by monitoring the concentration of bacterial signals, referred to as autoinducers (AIs). The widespread detection of AI-2 signals and its enzymatic synthase (LuxS) in bacteria suggests that AI-2 is an inter- and intraspecies communication signal. We have previously shown that antibiotic susceptibility is affected by AI-2 signaling in Streptococcus anginosus. Since chronic infections involve persistent biofilms resilient to antibiotic treatment, we explored the role of AI-2/LuxS in Streptococcus intermedius biofilm formation and cell viability when the organism was exposed to sub-MICs of ampicillin, ciprofloxacin, or tetracycline. The S. intermedius wild type (WT) and its isogenic luxS mutant, strain SI006, were exposed to sub-MICs of ampicillin, ciprofloxacin, or tetracycline. Biofilms were formed on polystyrene discs in microtiter plates. To assess planktonic cell viability, the ATP microbial viability assay was performed and the numbers of CFU were determined. For complementation assays, the AI-2 precursor dihydroxy pentanedione (DPD) was used as a supplement for SI006. Relative luxS expression was quantified by real-time PCR. The sub-MICs of all three antibiotics increased biofilm formation in S. intermedius WT. However, biofilm formation by SI006 was either unaffected or reduced (P < or = 0.05). Bacterial viability tests of biofilm and planktonic cell cultures indicated that SI006 was more susceptible to antibiotics than the WT. DPD complemented the luxS mutant phenotype. Real-time PCR revealed modest yet significant changes in luxS expression in the presence of antibiotic concentrations that increased biofilm formation. In conclusion, in S. intermedius, AI-2/LuxS was involved in antibiotic susceptibility and increased biofilm formation at sub-MICs of antibiotic.

  6. Identification of poultry meat-derived fatty acids functioning as quorum sensing signal inhibitors to autoinducer-2 (AI-2).

    PubMed

    Widmer, K W; Soni, K A; Hume, M E; Beier, R C; Jesudhasan, P; Pillai, S D

    2007-11-01

    Autoinducer-2 (AI-2) is a compound that plays a key role in bacterial cell-to-cell communication (quorum sensing). Previous research has shown certain food matrices inhibit this signaling compound. Using the reporter strain, Vibrio harveyi BB170, quorum-sensing inhibitors contained in poultry meat wash (PMW) samples were characterized by molecular weight and hydrophobic properties using liquid chromatography systems. Most fractions that demonstrated AI-2 inhibition were 13.7 kDa or less, and had hydrophobic properties. Hexane was used to extract inhibitory compounds from a PMW preparation and the extract was further separated by gas chromatography (GC). Several fatty acids were identified and quantified. Linoleic acid, oleic acid, palmitic acid, and stearic acid were each tested for inhibition at 0.1, 1, and 10 mM concentrations. All samples expressed AI-2 inhibition (ranging from approximately 25% to 99%). Fatty acids, combined in concentrations equivalent to those determined by GC analysis, expressed inhibition at 59.5%, but higher combined concentrations (10- and 100-fold) had inhibition at 84.4% and 69.5%, respectively. The combined fatty acids (100-fold) did not demonstrate a substantial decrease in colony plate counts, despite presenting high AI-2 inhibition. These fatty acids, through modulating quorum sensing by inhibition, may offer a unique means to control foodborne pathogens and reduce microbial spoilage.

  7. Identification of poultry meat-derived fatty acids functioning as quorum sensing signal inhibitors of autoinducer-2 (AI-2)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Autoinducer-2 (AI-2) is a compound that plays a key role in bacterial cell-to-cell communication (quorum sensing). Previous research has shown certain food matrices inhibit this signaling compound. Using the reporter strain, Vibrio harveyi BB170, quorum sensing inhibitors contained in poultry meat...

  8. Lysosome-Dependent Activation of Human Dendritic Cells by the Vaccine Adjuvant QS-21

    PubMed Central

    Welsby, Iain; Detienne, Sophie; N’Kuli, Francisca; Thomas, Séverine; Wouters, Sandrine; Bechtold, Viviane; De Wit, Dominique; Gineste, Romain; Reinheckel, Thomas; Elouahabi, Abdelatif; Courtoy, Pierre J.; Didierlaurent, Arnaud M.; Goriely, Stanislas

    2017-01-01

    The adjuvant properties of the saponin QS-21 have been known for decades. It is a component of the Adjuvant System AS01 that is used in several vaccine candidates. QS-21 strongly potentiates both cellular and humoral immune responses to purified antigens, yet how it activates immune cells is largely unknown. Here, we report that QS-21 directly activated human monocyte-derived dendritic cells (moDCs) and promoted a pro-inflammatory transcriptional program. Cholesterol-dependent QS-21 endocytosis followed by lysosomal destabilization and Syk kinase activation were prerequisites for this response. Cathepsin B, a lysosomal cysteine protease, was essential for moDC activation in vitro and contributed to the adjuvant effects of QS-21 in vivo. Collectively, these findings provide new insights into the pathways involved in the direct activation of antigen-presenting cells by a clinically relevant QS-21 formulation. PMID:28105029

  9. 50 CFR 680.42 - Limitations on use of QS, PQS, IFQ, and IPQ.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .../CPO Use Cap in QS Units CVC/CPC Use Cap in QS Units (A) Percent of the initial QS pool for BBR 1.0... State of Alaska. (5) Any person harvesting crab under a Class A CVO or Class A CVC IFQ Permit, except as... designated. (6) Any person harvesting crab under a Class B IFQ, CPO IFQ, CVC IFQ, or CPC IFQ permit...

  10. 50 CFR 680.42 - Limitations on use of QS, PQS, IFQ, and IPQ.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .../CPO Use Cap in QS Units CVC/CPC Use Cap in QS Units (A) Percent of the initial QS pool for BBR 1.0... State of Alaska. (5) Any person harvesting crab under a Class A CVO or Class A CVC IFQ Permit, except as... designated. (6) Any person harvesting crab under a Class B IFQ, CPO IFQ, CVC IFQ, or CPC IFQ permit...

  11. 50 CFR 680.42 - Limitations on use of QS, PQS, IFQ, and IPQ.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .../CPO Use Cap in QS Units CVC/CPC Use Cap in QS Units (A) Percent of the initial QS pool for BBR 1.0... State of Alaska. (5) Any person harvesting crab under a Class A CVO or Class A CVC IFQ Permit, except as... designated. (6) Any person harvesting crab under a Class B IFQ, CPO IFQ, CVC IFQ, or CPC IFQ permit...

  12. 50 CFR 680.42 - Limitations on use of QS, PQS, IFQ, and IPQ.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .../CPO Use Cap in QS Units CVC/CPC Use Cap in QS Units (A) Percent of the initial QS pool for BBR 1.0... State of Alaska. (5) Any person harvesting crab under a Class A CVO or Class A CVC IFQ Permit, except as... designated. (6) Any person harvesting crab under a Class B IFQ, CPO IFQ, CVC IFQ, or CPC IFQ permit...

  13. 50 CFR 680.42 - Limitations on use of QS, PQS, IFQ, and IPQ.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .../CPO Use Cap in QS Units CVC/CPC Use Cap in QS Units (A) Percent of the initial QS pool for BBR 1.0... State of Alaska. (5) Any person harvesting crab under a Class A CVO or Class A CVC IFQ Permit, except as... designated. (6) Any person harvesting crab under a Class B IFQ, CPO IFQ, CVC IFQ, or CPC IFQ permit...

  14. 50 CFR 680.41 - Transfer of QS, PQS, IFQ and IPQ.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... requirements in paragraph (c)(1)(iii) of this section. (vii) CVC or CPC QS An individual who is a U.S. citizen... for eligibility. (viii) CVC or CPC IFQ All eligible persons for CVC or CPC QS according to the... seeking CVC or CPC QS/IFQ, complete paragraphs (c)(2)(ii)(B), (c)(2)(ii)(C), (c)(2)(ii)(E), and...

  15. 50 CFR 680.41 - Transfer of QS, PQS, IFQ and IPQ.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... requirements in paragraph (c)(1)(iii) of this section. (vii) CVC or CPC QS An individual who is a U.S. citizen... for eligibility. (viii) CVC or CPC IFQ All eligible persons for CVC or CPC QS according to the... seeking CVC or CPC QS/IFQ, complete paragraphs (c)(2)(ii)(B), (c)(2)(ii)(C), (c)(2)(ii)(E), and...

  16. Proteomic analysis to identify the role of luxS/AI-2 mediated protein expression in Escherichia coli O157:H7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Autoinducer molecules are used by several microorganisms to control various bacterial 5 processes including virulence expression, biofilm and bioluminescence. The universal 6 autoinducer molecule AI-2 is hypothesized to mediate cell signaling in E. coli O157:H7. We investigated the role of AI-2 on...

  17. CERCLA Site Assessment questions and answers (Qs&As)

    SciTech Connect

    Traceski, T.T.

    1993-11-09

    This documents contains commonly asked questions and corresponding answers (Qs&As) on the CERCLA Site Assessment process. These questions were derived from DOE element responses to a solicitation calling for the identification of (unresolved) issues associated with the conduct of CERCLA site assessments, and from inquiries received during a series of Site Assessment Workshops provided by the Environmental Protection Agency (EPA) and the Office of Environmental Guidance, RCRA/CERCLA Division (EH-231). Answers to these questions were prepared by EH-231 in cooperation with the EPA Federal Facilities Team in Office of Solid Waste and Emergency Response, Site Assessment Branch, and in coordination with the Office of Environmental Compliance, Facilities Compliance Division (EH-222).

  18. Q-S (lag or anticipated) synchronization backstepping scheme in a class of continuous-time hyperchaotic systems--a symbolic-numeric computation approach.

    PubMed

    Yan, Zhenya

    2005-06-01

    First, a Q-S (lag or anticipated) synchronization of continuous-time dynamical systems is defined. Second, based on a backstepping design with one controller, a systematic, concrete, and automatic scheme is developed to investigate the Q-S (lag or anticipated) synchronization between the drive system and response system with a strict-feedback form. Two identical hyperchaotic Tamasevicius-Namajunas-Cenys(TNC) systems as well as the hyperchaotic TNC system and hyperchaotic Rossler system are chosen to illustrate the proposed scheme. Numerical simulations are used to verify the effectiveness of the proposed scheme. The scheme can also be extended to study Q-S (lag or anticipated) synchronization between other dynamical systems with strict-feedback forms. With the aid of symbolic-numeric computation, the scheme can be performed to yield automatically the scalar controller in computer.

  19. The Quantified Self (QS) Movement and Some Emerging Opportunities for the Educational Technology Field

    ERIC Educational Resources Information Center

    Lee, Victor R.

    2013-01-01

    The Quantified Self (QS) movement is a growing global effort to use new mobile and wearable technologies to automatically obtain personal data about everyday activities. The social and material infrastructure associated with the Quantified Self (QS) movement provides a number of ideas that educational technologists should consider incorporating…

  20. 50 CFR 679.90 - Allocation, use, and transfer of Amendment 80 QS permits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... QS units for that Amendment 80 vessel for BSAI flathead sole. (v) BSAI Atka mackerel. (A) Multiply... this section by the Amendment 80 initial QS pool for BSAI Atka mackerel as set forth in Table 32 to... mackerel. (B) If an Amendment 80 vessel is an Amendment 80 non-mackerel vessel, determine the percentage...

  1. 50 CFR 679.90 - Allocation, use, and transfer of Amendment 80 QS permits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... QS units for that Amendment 80 vessel for BSAI flathead sole. (v) BSAI Atka mackerel. (A) Multiply... this section by the Amendment 80 initial QS pool for BSAI Atka mackerel as set forth in Table 32 to... mackerel. (B) If an Amendment 80 vessel is an Amendment 80 non-mackerel vessel, determine the percentage...

  2. 50 CFR 679.90 - Allocation, use, and transfer of Amendment 80 QS permits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... QS units for that Amendment 80 vessel for BSAI flathead sole. (v) BSAI Atka mackerel. (A) Multiply... this section by the Amendment 80 initial QS pool for BSAI Atka mackerel as set forth in Table 32 to... mackerel. (B) If an Amendment 80 vessel is an Amendment 80 non-mackerel vessel, determine the percentage...

  3. 50 CFR 679.90 - Allocation, use, and transfer of Amendment 80 QS permits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... QS units for that Amendment 80 vessel for BSAI flathead sole. (v) BSAI Atka mackerel. (A) Multiply... this section by the Amendment 80 initial QS pool for BSAI Atka mackerel as set forth in Table 32 to... mackerel. (B) If an Amendment 80 vessel is an Amendment 80 non-mackerel vessel, determine the percentage...

  4. XMM-Newton observations of the X-ray soft polar QS Telescopii

    NASA Astrophysics Data System (ADS)

    Traulsen, I.; Reinsch, K.; Schwope, A. D.; Burwitz, V.; Dreizler, S.; Schwarz, R.; Walter, F. M.

    2011-05-01

    Context. On the basis of XMM-Newton observations, we investigate the energy balance of selected magnetic cataclysmic variables, which have shown an extreme soft-to-hard X-ray flux ratio in the ROSAT All-Sky Survey. Aims: We intend to establish the X-ray properties of the system components, their flux contributions, and the accretion geometry of the X-ray soft polar QS Tel. In the context of high-resolution X-ray analyses of magnetic cataclysmic variables, this study will contribute to better understanding the accretion processes on magnetic white dwarfs. Methods: During an intermediate high state of accretion of QS Tel, we have obtained 20 ks of XMM-Newton data, corresponding to more than two orbital periods, accompanied by simultaneous optical photometry and phase-resolved spectroscopy. We analyze the multi-wavelength spectra and light curves and compare them to former high- and low-state observations. Results: Soft emission at energies below 2 keV dominates the X-ray light curves. The complex double-peaked maxima are disrupted by a sharp dip in the very soft energy range (0.1-0.5 keV), where the count rate abruptly drops to zero. The EPIC spectra are described by a minimally absorbed black body at 20 eV and two partially absorbed mekal plasma models with temperatures around 0.2 and 3 keV. The black-body-like component arises from one mainly active, soft X-ray bright accretion region nearly facing the mass donor. Parts of the plasma emission might be attributed to the second, virtually inactive pole. High soft-to-hard X-ray flux ratios and hardness ratios demonstrate that the high-energy emission of QS Tel is substantially dominated by its X-ray soft component. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

  5. ACTIVITY ON THE M STAR OF QS Vir

    SciTech Connect

    Ribeiro, T.; Baptista, R.; Kafka, S.; Tappert, C.

    2010-03-15

    We report analysis of VRIJH photometry and phase-resolved optical spectroscopy of the eclipsing DA white dwarf (WD) plus dMe dwarf binary QS Vir. Modeling of the photometric data yields an inclination of i = 74.9 {+-} 0.6 and a mass ratio of q = M {sub 2}/M {sub 1} = 0.50 {+-} 0.05. Our Doppler maps indicate the presence of material in the Roche lobe of the WD, at a location near the M star, likely due to accretion from the stellar wind of the M star (as opposed to Roche-lobe overflow accretion). We also constructed images of the brightness distribution of the M star at different epochs which reveal the location of two stable active regions. Doppler tomography shows that the majority of the hydrogen and Ca II H and K emission originates on the active M dwarf, likely distributed in two preferred activity longitudes, similar to active regions on BY Dra and FK Comae systems.

  6. Northern California Seismic Attenuation: 3-D Qp and Qs models

    NASA Astrophysics Data System (ADS)

    Eberhart-Phillips, D. M.

    2015-12-01

    The northern California crust exhibits a wide range of rock types and deformation processes which produce pronounced heterogeneity in regional attenuation. Using local earthquakes, 3-D Qp and Qs crustal models have been obtained for this region which includes the San Andreas fault system, the Central Valley, the Sierra Nevada batholith, and the Mendocino subduction volcanic system. Path attenuation t* values were determined from P and S spectra of 959 spatially distributed earthquakes, magnitude 2.5-6.0 from 2005-2014, using 1254 stations from NCEDC networks and IRIS Mendocino and Sierra Nevada temporary arrays. The t* data were used in Q inversions, using existing hypocenters and 3-D velocity models, with basic 10-km node spacing. The uneven data coverage was accounted for with linking of nodes into larger areas in order to provide useful Q images across the 3-D volume. The results at shallow depth (< 2 km) show very low Q in the Sacramento Delta, the Eureka area, and parts of the Bay Area. In the brittle crust, fault zones that have high seismicity exhibit low Q. In the lower crust, low Q is observed along fault zones that have large cumulative displacement and have experienced grain size reduction. Underlying active volcanic areas, low Q features are apparent below 20-km depth. Moderately high Q is associated with igneous rocks of the Sierra Nevada and Salinian block, while the Franciscan subduction complex shows moderately low Q. The most prominent high Q feature is related to the Great Valley Ophiolite.

  7. Sediment Thicknesses and Qs vs. Qp Relations in the Kachchh Rift Basin, Gujarat, India Using Sp Converted Phases

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik

    2007-01-01

    Delineation of the top sedimentary structure and its Qs vs. Qp relationship using the travel-time difference of direct S and converted Sp phase is key to understanding the seismic hazard of any sedimentary basin area. We constructed filtered displacement waveforms from local ETNA Episensor acceleration recordings as well as local velocity recordings of aftershocks of the 2001 Bhuj earthquake recorded by the Kachchh seismological network of the National Geophysical Research Institute (NGRI), Hyderabad, India during 2001 2004. Stations are within 15 70km of epicenters, and the resulting displacement waveforms are generally simple, displaying prominent P, Sp, and S wave pulses. Particle motion of P and S waves suggest near-vertical raypaths consistent with preliminary depth estimates. The direct S wave on the horizontal component is characterized by lower frequency content than the converted Sp phase on the vertical component. This difference in frequency content between S and Sp phases can be explained in terms of different attenuation effects for P and S waves in the unconsolidated sediments. The Sp phase is generated by S-to-P phase conversion at the base of Mesozoic sediments of the Kachchh basin. Travel-time inversion (VELEST) of 2565 P and 2380 S arrivals from 658 well located aftershocks recorded at 8 14 three-component local seismic stations led to 1 D velocity models indicated very slow sediments in the upper 0 2 km depth range (Vp: 2.92 km/s and Vs: 0.90 km/s) and an increasing trend of velocities with depth at 2 40 km depth. The estimated sediment thicknesses beneath 12 accelerograph and 6 seismograph sites from the estimated velocity model and the travel-time difference between S and converted Sp phases reaches a maximum of (1.534 ± 0.117) km beneath Bandri (near the location of 2001 Bhuj mainshock) and attains a minimum sediment thickness of (0.858 ± 0.104) km beneath Ramvav and Burudia. The spectral ratios between Sp and S from 159 three

  8. Q-S (complete or anticipated) synchronization backstepping scheme in a class of discrete-time chaotic (hyperchaotic) systems: a symbolic-numeric computation approach.

    PubMed

    Yan, Zhenya

    2006-03-01

    First, a type of Q-S (complete or anticipated) synchronization is defined in discrete-time dynamical systems. Second, based on backstepping design with a scalar controller, a systematic, concrete and automatic scheme is presented to investigate Q-S (complete or anticipated) synchronization between the discrete-time drive system and response system with strict-feedback form. Finally, the proposed scheme is used to illustrate Q-S (complete or anticipated) synchronization between the two-dimensional discrete-time Lorenz system and Fold system, as well as the three-dimensional hyperchaotic discrete-time Rossler system and generalized discrete-time Rossler system. Moreover numerical simulations are used to verify the effectiveness of the proposed scheme. Our scheme can be also extended to investigate Q-S (complete or anticipated) synchronization between other discrete-time dynamical systems with strict-feedback forms. With the aid of symbolic-numeric computation, the scheme can be performed to yield automatically the scalar controller and to verify its effectiveness in computer.

  9. Derivation of a Provisional, Age-dependent, AIS2+ Thoracic Risk Curve for the THOR50 Test Dummy via Integration of NASS Cases, PMHS Tests, and Simulation Data.

    PubMed

    Laituri, Tony R; Henry, Scott; El-Jawahri, Raed; Muralidharan, Nirmal; Li, Guosong; Nutt, Marvin

    2015-11-01

    A provisional, age-dependent thoracic risk equation (or, "risk curve") was derived to estimate moderate-to-fatal injury potential (AIS2+), pertaining to men with responses gaged by the advanced mid-sized male test dummy (THOR50). The derivation involved two distinct data sources: cases from real-world crashes (e.g., the National Automotive Sampling System, NASS) and cases involving post-mortem human subjects (PMHS). The derivation was therefore more comprehensive, as NASS datasets generally skew towards younger occupants, and PMHS datasets generally skew towards older occupants. However, known deficiencies had to be addressed (e.g., the NASS cases had unknown stimuli, and the PMHS tests required transformation of known stimuli into THOR50 stimuli). For the NASS portion of the analysis, chest-injury outcomes for adult male drivers about the size of the THOR50 were collected from real-world, 11-1 o'clock, full-engagement frontal crashes (NASS, 1995-2012 calendar years, 1985-2012 model-year light passenger vehicles). The screening for THOR50-sized men involved application of a set of newly-derived "correction" equations for self-reported height and weight data in NASS. Finally, THOR50 stimuli were estimated via field simulations involving attendant representative restraint systems, and those stimuli were then assigned to corresponding NASS cases (n=508). For the PMHS portion of the analysis, simulation-based closure equations were developed to convert PMHS stimuli into THOR50 stimuli. Specifically, closure equations were derived for the four measurement locations on the THOR50 chest by cross-correlating the results of matched-loading simulations between the test dummy and the age-dependent, Ford Human Body Model. The resulting closure equations demonstrated acceptable fidelity (n=75 matched simulations, R2≥0.99). These equations were applied to the THOR50-sized men in the PMHS dataset (n=20). The NASS and PMHS datasets were combined and subjected to survival

  10. V773 Cas, QS Aql, and BR Ind: Eclipsing Binaries as Parts of Multiple Systems

    NASA Astrophysics Data System (ADS)

    Zasche, P.; Juryšek, J.; Nemravová, J.; Uhlař, R.; Svoboda, P.; Wolf, M.; Hoňková, K.; Mašek, M.; Prouza, M.; Čechura, J.; Korčáková, D.; Šlechta, M.

    2017-01-01

    Eclipsing binaries remain crucial objects for our understanding of the universe. In particular, those that are components of multiple systems can help us solve the problem of the formation of these systems. Analysis of the radial velocities together with the light curve produced for the first time precise physical parameters of the components of the multiple systems V773 Cas, QS Aql, and BR Ind. Their visual orbits were also analyzed, which resulted in slightly improved orbital elements. What is typical for all these systems is that their most dominant source is the third distant component. The system V773 Cas consists of two similar G1-2V stars revolving in a circular orbit and a more distant component of the A3V type. Additionally, the improved value of parallax was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following: the inner eclipsing pair is composed of B6V and F1V stars, and the third component is of about the B6 spectral type. The outer orbit has high eccentricity of about 0.95, and observations near its upcoming periastron passage between the years 2038 and 2040 are of high importance. Also, the parallax of the system was derived to be about 2.89 mas, moving the star much closer to the Sun than originally assumed. The system BR Ind was found to be a quadruple star consisting of two eclipsing K dwarfs orbiting each other with a period of 1.786 days; the distant component is a single-lined spectroscopic binary with an orbital period of about 6 days. Both pairs are moving around each other on their 148 year orbit. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 091.D-0122(A), 094.A-9029(D), 095.A-9032(A), and 096.A-9039(A) and also on data from the 2 m telescope at the Ondřejov observatory in the Czech Republic

  11. Small Molecule Inhibitors of AI-2 Signaling in Bacteria: State-of-the-Art and Future Perspectives for Anti-Quorum Sensing Agents

    PubMed Central

    Guo, Min; Gamby, Sonja; Zheng, Yue; Sintim, Herman O.

    2013-01-01

    Bacteria respond to different small molecules that are produced by other neighboring bacteria. These molecules, called autoinducers, are classified as intraspecies (i.e., molecules produced and perceived by the same bacterial species) or interspecies (molecules that are produced and sensed between different bacterial species). AI-2 has been proposed as an interspecies autoinducer and has been shown to regulate different bacterial physiology as well as affect virulence factor production and biofilm formation in some bacteria, including bacteria of clinical relevance. Several groups have embarked on the development of small molecules that could be used to perturb AI-2 signaling in bacteria, with the ultimate goal that these molecules could be used to inhibit bacterial virulence and biofilm formation. Additionally, these molecules have the potential to be used in synthetic biology applications whereby these small molecules are used as inputs to switch on and off AI-2 receptors. In this review, we highlight the state-of-the-art in the development of small molecules that perturb AI-2 signaling in bacteria and offer our perspective on the future development and applications of these classes of molecules. PMID:23994835

  12. Evaluation of AIS-2 (1986) data over hydrothermally altered granitoid rocks of the Singatse Range (Yerington) Nevada and comparison with 1985 AIS-1 data

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.

    1987-01-01

    The Airborne Imaging Spectrometer-2 (AIS-2) flights along 2 subparallel lines (bearing 013) were designed to traverse 3 major rock assemblages - the Triassic sedimentary sequence; the granitoid rocks of the Yerington batholith and the Tertiary ignimbritic ash flow and ash fall tuffs. The first 2 sites are hydrothermally altered to a quartz-sericite-tourmaline mineralogy. The first AIS-2 data set showed numerous line dropouts and a considerable number of randomly distributed dark pixels. A second decommutation reduced the dropout essentially to near zero and the dark pixels by about 75 percent. Vertical striping was removed by histogram matching, column by column. A log residual spectrum was calculated which showed the departure of a 2 x 2 pixel area from the spatially and spectrally averaged scene. A 1:1 correlation was found with the log residual AIS-2 data and a large open pit area of gypsum. An area with known sericite agreed with the overflight data, and an area known to be free of any significant amount of O-H bearing materials showed no evidence of any in the AIS-2 log residuals.

  13. Calibrating accelerometer sensor on android phone with Accelerograph TDL 303 QS for earthquake online recorder

    NASA Astrophysics Data System (ADS)

    Riantana, R.; Darsono, D.; Triyono, A.; Azimut, H. B.

    2016-11-01

    Calibration of the android censor was done by placing the device in a mounting at side of accelerograph TDL 303 QS that will be a means of comparison. Leveling of both devices was set same, so that the state of the device can be assumed same anyway. Then applied vibrations in order to have the maximum amplitude value of both censor, so it can be found equality of the coefficient of proportionality both of them. The results on both devices obtain the Peak Ground Acceleration (PGA) as follows, on the x axis (EW) android censor is obtained PGA -2.4478145 gal than at TDL 303 QS obtained PGA -2.5504 gal, the y-axis (NS) on the censor android obtained PGA 3.0066964 gal than at TDL 303 QS obtained PGA 3.2073 gal, the z-axis (UD) on the android censor obtained PGA -14.0702377 gal than at TDL 303 QS obtained PGA -13.2927 gal, A correction value for android accelerometer censor is ± 0.1 gal for the x-axis (EW), ± 0.2 gal for the y-axis (NS), and ± 0.7 gal for the z-axis (UD).

  14. 50 CFR 680.41 - Transfer of QS, PQS, IFQ and IPQ.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... to represent, and a demonstration that the non-profit organization has the management skills and... Section 680.41 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND... ZONE OFF ALASKA Quota Management Measures § 680.41 Transfer of QS, PQS, IFQ and IPQ. (a) General....

  15. Synthesis and Preclinical Evaluation of QS-21 Variants Leading to Simplified Vaccine Adjuvants and Mechanistic Probes

    PubMed Central

    Chea, Eric K.; Fernández-Tejada, Alberto; Damani, Payal; Adams, Michelle M.; Gardner, Jeffrey R.; Livingston, Philip O.; Ragupathi, Govind; Gin, David Y.

    2012-01-01

    QS-21 is a potent immunostimulatory saponin that is currently under clinical investigation as an adjuvant in various vaccines to treat infectious diseases, cancers, and congnitive disorders. Herein we report the design, synthesis, and preclinical evaluation of simplified QS-21 congeners to define key structural features that are critical for adjuvant activity. Truncation of the linear tetrasaccharide domain revealed that a trisaccharide variant is equipotent to QS-21 while the corresponding disaccharide and monosaccharide congeners are more toxic or less potent, respectively. Modification of the acyl domain in the trisaccharide series revealed that a terminal carboxylic acid is well-tolerated while a terminal amine results in reduced adjuvant activity. Acylation of the terminal amine can restore adjuvant activity and enables the synthesis of fluorescently-labeled QS-21 variants. Cellular studies with these probes revealed that, contrary to conventional wisdom, the most highly adjuvant active of these fluorescently-labeled saponins does not simply associate with the plasma membrane, but rather is internalized by dendritic cells. PMID:22866694

  16. 50 CFR 679.90 - Allocation, use, and transfer of Amendment 80 QS permits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Total for that Amendment 80 vessel for that Amendment 80 species. (ii) Aleutian Islands Pacific ocean... Aleutian Islands Pacific ocean perch and BSAI Pacific cod as calculated in paragraph (d)(1)(i)(D) of this section by the Amendment 80 initial QS pool for Aleutian Islands Pacific ocean perch and BSAI Pacific...

  17. Simpson's Paradox and Confounding Factors in University Rankings: A Demonstration Using QS 2011-12 Data

    ERIC Educational Resources Information Center

    Soh, Kay Cheng

    2012-01-01

    University ranking has become ritualistic in higher education. Ranking results are taken as bona fide by rank users. Ranking systems usually use large data sets from highly heterogeneous universities of varied backgrounds. This poses the problem of Simpson's Paradox and the lurking variables causing it. Using QS 2011-2012 Ranking data, the dual…

  18. Foreign Object Debris: FOD Prevention QS210LSK-REV

    NASA Technical Reports Server (NTRS)

    Randolph, Sherry; Seaman, John

    2004-01-01

    Housekeeping in the space industry? You may think the idea isn't technical enough for the shuttle program. Yet, eliminating Foreign Object Debris or FOD is an important goal for USA and NASA. The justification for this effort is based on data from the aeronautics industry. Experience has shown that if debris is not controlled, it may later cause a variety of in-flight issues. FOD can result in material damage, or make systems and equipment inoperable unsafe, or less efficient

  19. Functional definition of LuxS, an autoinducer-2 (AI-2) synthase and its role in full virulence of Streptococcus suis serotype 2.

    PubMed

    Cao, Min; Feng, Youjun; Wang, Changjun; Zheng, Feng; Li, Ming; Liao, Hui; Mao, Yinghua; Pan, Xiuzhen; Wang, Jing; Hu, Dan; Hu, Fuquan; Tang, Jiaqi

    2011-12-01

    Quorum sensing is a widespread chemical communication in response to fluctuation of bacterial population density, and has been implicated into bacterial biofilm formation and regulation of expression of virulence factors. The luxS gene product, S-ribosylhomocysteinase, catalizes the last committed step in biosynthetic pathway of autoinducer 2 (AI-2), a signaling molecule for inter-species quorum sensing. We found a luxS homologue in 05ZYH33, an epidemic strain of Streptococcus suis serotype 2 (SS2) in China. A luxS null mutant (ΔluxS) of 05ZYH33 strain was obtained using an approach of homologous recombination. LuxS was determined to be required for AI-2 production in 05ZYH33 strain of S. suis 2. Inactivation of luxS gene led to a wide range of phenotypic changes including thinner capsular walls, increased tolerance to H(2)O(2), reduced adherence capacity to epithelial cells, etc. In particular, loss of LuxS impaired dramatically its full virulence of SS2 in experimental model of piglets, and functional complementation restored it nearly to the level of parent strain. Genome-wide transcriptome analyses suggested that some known virulence factors such as CPS are down-regulated in the ΔluxS mutant, which might in part explain virulence attenuation by luxS deletion. Similarly, 29 of 71 genes with different expression level were proposed to be targets candidate regulated by LuxS/AI-2-dependent quorum sensing.

  20. Investigation on Electrochemical Property of AB/AI2O3- coated Li-excess Mn-based Layered Oxides

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Takada, K.; Arachi, Y.; Okumura, T.; Shikano, M.; Nitani, H.

    2016-05-01

    The AB and/or Al2O3-coated Li1.20Mn0.55Ni0.16Co0.09O2 were prepared by the mechanochemical reaction. The optimal condition for sample preparation was selected to be the rotation speed of 2000 rpm and the reaction time of 5 minutes by SEM and XANES measurements. Surface analysis using SEM and XANES data demonstrated that all the samples were rather uniformly covered with AB and/or nano-AEO3 particles. The AEO3- coated samples showed less discharge capacity and C-rate performance compared with the pristine sample, while the AB/Al2O3-coated sample showed almost the same discharge capacity and C-rate performance and had better cycle performance at 318 K compared with the pristine sample. These results demonstrate that the mechanochemical AB/Al2O3-coating process is an effective way of improving the cycle performance at high temperature without degrading the discharge capacity and C-rate performance.

  1. DETECTION OF ACCRETION X-RAYS FROM QS Vir: CATACLYSMIC OR A LOT OF HOT AIR?

    SciTech Connect

    Matranga, Marco; Drake, Jeremy J.; Kashyap, Vinay; Steeghs, Danny

    2012-03-10

    An XMM-Newton observation of the nearby 'pre-cataclysmic' short-period (P{sub orb} = 3.62 hr) binary QS Vir (EC 13471-1258) revealed regular narrow X-ray eclipses when the white dwarf passed behind its M2-4 dwarf companion. The X-ray emission provides a clear signature of mass transfer and accretion onto the white dwarf. The low-resolution XMM-Newton EPIC spectra are consistent with a cooling flow model and indicate an accretion rate of M-dot = 1.7 Multiplication-Sign 10{sup -13} M{sub sun} yr{sup -1}. At 48 pc distant, QS Vir is then the second nearest accreting cataclysmic variable known, with one of the lowest accretion rates found to date for a non-magnetic system. To feed this accretion through a wind would require a wind mass-loss rate of M-dot {approx}2 Multiplication-Sign 10{sup -12} M{sub sun} yr{sup -1} if the accretion efficiency is of the order of 10%. Consideration of likely mass-loss rates for M dwarfs suggests this is improbably high and pure wind accretion unlikely. A lack of accretion disk signatures also presents some difficulties for direct Roche lobe overflow. We speculate that QS Vir is on the verge of Roche lobe overflow, and that the observed mass transfer could be supplemented by upward chromospheric flows on the M dwarf, analogous to spicules and mottles on the Sun, that escape the Roche surface to be subsequently swept up into the white dwarf Roche lobe. If so, QS Vir would be in a rare evolutionary phase lasting only a million years. The X-ray luminosity of the M dwarf estimated during primary eclipse is L{sub X} = 3 Multiplication-Sign 10{sup 28} erg s{sup -1}, which is consistent with that of rapidly rotating 'saturated' K and M dwarfs.

  2. The Crowded Magnetosphere Of The Post-Common-Envelope Binary QS Virginis

    NASA Astrophysics Data System (ADS)

    Hill, Colin

    2016-06-01

    We present high-speed photometry and high-resolution spectroscopy of the short-period (Prot = 3.6 h) eclipsing post-common-envelope binary QS Virginis (QS Vir). Our UVES spectra span in excess of 6 orbits, over more than a year, and reveal the presence of several large prominences passing in front of both the M star and its white dwarf (WD) companion. Despite showing small variations on a time-scale of days, they persist for more than a year and may last decades. Roche tomography reveals a heavily spotted M star, with long-lived spots remaining in fixed locations, preferentially found on the hemisphere facing the WD. We find the 14,220 ± 350 K WD is relatively massive at 0.782 ± 0.013 M(_{odot}),with a radius of0.01068 ± 0.00007 R(_{odot}), consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006 M(_{odot})and a radius of0.381 ± 0.003 R(_{odot}), also consistent with evolutionary models. Since the M star's radius is still within its Roche lobe and there is no evidence that it is overinflated, we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semidetached.

  3. Enhancing Immunogenicity of Cancer Vaccines: QS-21 as an Immune Adjuvant

    PubMed Central

    Gin, David Y.; Slovin, Susan F.

    2014-01-01

    Saponins comprise a class of plant natural products that incorporate a lipophilic terpenoid core, to which is appended one or more carbohydrate residues. They are amphiphilic molecules and often exhibit toxic biological profiles, likely as a result of their roles as vital components in protective coatings to defend against phytopathogen infection and insect predation. The most notable of adjuvant-active saponins investigated for vaccine development come from the Chilean Soapbark Tree, Quillaja saponaria (i.e., QS). More than 30 years ago, semi-purified extracts (i.e., Quil A) from the cortex of Quillaja saponaria were found to be highly effective as adjuvants in veterinary vaccines. However, due to significant and variable toxicity effects, Quil A was not deemed appropriate for human vaccines. More refined purification methods have led to multiple fractions which are derived from the original plant extract. As such, QS-21 to date appears to be one of the more scientifically interesting and robust adjuvants in use in vaccinology. The role of QS-21 as an adjuvant for use in a variety of cancer vaccine trials and its comparison to other adjuvants is discussed in this review. PMID:25473385

  4. Central Role of CD169+ Lymph Node Resident Macrophages in the Adjuvanticity of the QS-21 Component of AS01

    PubMed Central

    Detienne, Sophie; Welsby, Iain; Collignon, Catherine; Wouters, Sandrine; Coccia, Margherita; Delhaye, Sophie; Van Maele, Laurye; Thomas, Séverine; Swertvaegher, Maëlle; Detavernier, Aurélie; Elouahabi, Abdelatif; Goriely, Stanislas; Didierlaurent, Arnaud M.

    2016-01-01

    Saponins represent a promising class of vaccine adjuvant. Together with the TLR4-ligand MPL, QS-21 is part of the Adjuvant System AS01, a key component of the malaria and zoster candidate vaccines that display demonstrated clinical efficacy. However, the mechanism of action of QS-21 in this liposomal formulation is poorly understood. Upon intra-muscular immunisation, we observed that QS-21 rapidly accumulated in CD169+ resident macrophages of the draining lymph node where it elicited a local innate immune response. Depletion of these cells abrogated QS-21-mediated innate cell recruitment to the lymph node, dendritic cell (DC) phenotypic maturation as well as the adjuvant effect on T-cell and antibody responses to co-administered antigens. DCs rather than lymph node-resident macrophages were directly involved in T-cell priming by QS-21, as revealed by the decrease in antigen-specific T-cell response in Batf3−/− mice. Further analysis showed that the adjuvant effect of QS-21 depended on the integration of Caspase-1 and MyD88 pathways, at least in part through the local release of HMGB1. Taken together, this work unravels the key role of lymph node sentinel macrophage in controlling the adjuvant effect of a molecule proven to improve vaccine response in humans. PMID:27996000

  5. Amplitude of Sdiff across Asia: effects of velocity gradient and Qs in the D'' region and the asphericity of the mantle

    NASA Astrophysics Data System (ADS)

    Kuo, Ban-Yuan

    1999-11-01

    The amplitudes of diffracted SH (S diff) normalized to SKS, together with the S diff-SKS times, were analyzed to constrain the structure of the D" region beneath Asia and the northernmost Indian Ocean. While the S diff-SKS residuals (δt; relative to the Preliminary Reference Earth model, or PREM) are consistently negative from 95° to 120°, the amplitude residuals of S diff/SKS (δ A) show two trends of distance dependence, corresponding to distinct seismic structures in two adjacent zones in D". In zone A, δ A increases significantly with distance, suggesting the presence of a negative velocity gradient in the base of the mantle. The travel time residuals independently require that the average velocity of zone A be faster than that of PREM. One-dimensional structures that reconcile both sets of constraints were sought through systematic forwarding modeling. Models with negative gradients that satisfy δt's match δ A's to an acceptable degree only if a high-quality factor ( Qs) is assumed. The preferred model for zone A has a 400-500 km thick negative gradient layer, with a ~4% velocity discontinuity at the top and Qs = 1000, an about three-fold increase from the PREM value. In zone B, the amplitude-distance curve is virtually flat, and a 200-300 km thick high-velocity layer with PREM-like gradient and Qs explains both observations well. To assess the role of mantle asphericity in δ A, we estimate the strength of focusing of the S waves into the Fresnel zone at the onset of diffraction in vertical cross-sections of 3-D tomographic models SAW12D and SKS12WM13. Both models predict stronger focusing in zone A than in zone B. The focusing effect is translated to a positive base-line shift in δ A, which, if applied to the model predictions, alleviates the need for an extremely high Qs in zone A. The simple 2-D experiment suggests that velocity gradient and the anelastic attenuation of the D" layer as well as the mantle heterogeneity all probably contribute to the

  6. The crowded magnetosphere of the post-common-envelope binary QS Virginis

    NASA Astrophysics Data System (ADS)

    Parsons, S. G.; Hill, C. A.; Marsh, T. R.; Gänsicke, B. T.; Watson, C. A.; Steeghs, D.; Dhillon, V. S.; Littlefair, S. P.; Copperwheat, C. M.; Schreiber, M. R.; Zorotovic, M.

    2016-05-01

    We present high-speed photometry and high-resolution spectroscopy of the eclipsing post-common-envelope binary QS Virginis (QS Vir). Our Ultraviolet and Visual Echelle Spectrograph (UVES) spectra span multiple orbits over more than a year and reveal the presence of several large prominences passing in front of both the M star and its white dwarf companion, allowing us to triangulate their positions. Despite showing small variations on a time-scale of days, they persist for more than a year and may last decades. One large prominence extends almost three stellar radii from the M star. Roche tomography reveals that the M star is heavily spotted and that these spots are long-lived and in relatively fixed locations, preferentially found on the hemisphere facing the white dwarf. We also determine precise binary and physical parameters for the system. We find that the 14 220 ± 350 K white dwarf is relatively massive, 0.782 ± 0.013 M⊙, and has a radius of 0.010 68 ± 0.000 07 R⊙, consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006 M⊙ and a radius of 0.381 ± 0.003 R⊙, also consistent with evolutionary models. We find that the magnesium absorption line from the white dwarf is broader than expected. This could be due to rotation (implying a spin period of only ˜700 s), or due to a weak (˜100 kG) magnetic field, we favour the latter interpretation. Since the M star's radius is still within its Roche lobe and there is no evidence that it is overinflated, we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semidetached.

  7. Inhibition of Coenzyme Qs Accumulation in Engineered Escherichia coli by High Concentration of Farnesyl Diphosphate

    PubMed Central

    Samoudi, Mojtaba; Omid Yeganeh, Negar; Shahbani Zahiri, Hossein; Shariati, Parvin; Hajhosseini, Reza

    2015-01-01

    Background: Coenzyme Q 10 (CoQ 10 ) is an isoprenoid component used widely in nutraceutical industries. Farnesyl diphosphate synthase (FPPS) is a responsible enzyme for biosynthesis of farnesyl diphosphate (FPP), a key precursor for CoQs production. This research involved investigating the effect of FPPS over-expression on CoQs production in engineered CoQ 10 -producing Escherichia coli (E. coli). Methods: Two CoQ 10 -producing strains, as referred to E. coli Ba and E. coli Br, were transformed by the encoding gene for FPPS (ispA) under the control of either the trc or P BAD promoters. Results: Over-expression of ispA under the control of P BAD promoter led to a relative increase in CoQ 10 production only in recombinant E. coli Br although induction by arabinose resulted in partial reduction of CoQ 10 production in both recombinant E. coli Ba and E. coli Br strains. Over-expression of ispA under the control of stronger trc promoter, however, led to a severe decrease in CoQ 10 production in both recombinant E. coli Ba and E. coli Br strains, as reflected by reductions from 629±40 to 30±13 and 564±28 to 80±14 μg/g Dried Cell Weight (DCW), respectively. The results showed high level of FPP reduces endogenous CoQ 8 production as well and that CoQs are produced in a complimentary manner, as the increase in production of one decreases the production of the other. Conclusion: The reduction in CoQ 10 production can be a result of Dds inhibition by high FPP concentration. Therefore, more effort is needed to verify the role of intermediate metabolite concentration and to optimize production of CoQ 10 . PMID:26306151

  8. Systemic Synthesis Questions [SSynQs] as Tools to Help Students to Build Their Cognitive Structures in a Systemic Manner

    NASA Astrophysics Data System (ADS)

    Hrin, Tamara N.; Fahmy, Ameen F. M.; Segedinac, Mirjana D.; Milenković, Dušica D.

    2016-08-01

    Many studies dedicated to the teaching and learning of organic chemistry courses have emphasized that high school students have shown significant difficulties in mastering the concepts of this discipline. Therefore, the aim of our study was to help students to overcome these difficulties by applying systemic synthesis questions, [SSynQs], as the instructional method in our intervention. This work shows that students from the group exposed to the new teaching method achieved higher scores on final testing than students from the control group, who were taught by the traditional method, when students' achievements in conventional, linear questions [LQs] and in [SSynQs] were studied. These results were followed by observation of lower levels of mental effort by students from the intervention group, and higher levels of mental effort in the control group, invested during solving both types of questions. This correlation between achievement and mental effort resulted in high instructional efficiency for the applied method in the intervention group, [SSynQs], and low instructional efficiency for the traditional teaching and learning method applied in the control group. A systemic triangular relation between achievement, mental effort, and instructional efficiency, established by each group and gender, emphasized that the application of [SSynQs] was more suited to female students than for male students because of [SSynQs] characteristics as teaching and learning tools and because of learning style and ability differences between genders.

  9. Solvothermal crystal growth of CuSbQ{sub 2} (Q=S, Se) and the correlation between macroscopic morphology and microscopic structure

    SciTech Connect

    Zhou Jian; Bian Guoqing; Zhu Qinyu; Zhang Yong; Li Chunying; Dai Jie

    2009-02-15

    A low temperature solvothermal method has been successfully used for preparation of two semiconductor compounds CuSbQ{sub 2} (Q=S(1), Se(2)) by the reactions of Cu, Sb and S(or Se) powders in 1,2-diaminopropane at 160 deg. C for 10 days. The crystal structure of 2 was determined first time using single crystal X-ray diffraction analyses. The structures of 1 and 2 are discussed in the view of covalent bonds and weak interactions. Double CuSbQ{sub 2} layers are assembled to a 3-D network structure by Cu...Sb and Q...Sb secondary bonds. In contrast with the isostructure of the two materials, the crystal morphology of them is quite different, brick-like crystals for CuSbS{sub 2} and plank-like crystals for CuSbSe{sub 2}. The phenomenon is related to their different inter-planar interactions. Semiconductor properties of the microcrystal samples are measured and the band gaps of 1 and 2 are 1.38 and 1.05 eV, respectively. - Graphical abstract: Two isostructural compounds, CuSbQ{sub 2} (Q=S, Se), display different morphologies in crystals, which is explained by comparing the strength of the interlayer interactions based on the crystal structure data.

  10. Bulk sediment Qp and Qs in the Mississippi embayment, central United States

    USGS Publications Warehouse

    Langston, C.A.; Bodin, P.; Powell, C.; Withers, M.; Horton, S.; Mooney, W.

    2005-01-01

    We have estimated P-wave and S-wave anelastic attenuation coefficients for the thick, unconsolidated sediments of the Mississippi embayment, central United States, using the spectral distance decay of explosion P and Rayleigh waves. The sediment-trapped P wave, Psed, is observed to ranges of 80 km at 10 Hz, and 1-Hz Rayleigh waves are observed out to 130 km from a 5000-lb borehole explosion in the northern part of the embayment. Rayleigh waves of 4 Hz are seen to distances of 3 km from a smaller 50-lb explosion. Analysis of the group velocity and amplitude-distance decay of both waves yields an average Qs of 100 and Qp of 200 for embayment sediments that are independent of frequency. Scatter in the Q estimates comes from interference of multiple P-wave reverberations and Rayleigh-wave modes. The attenuation model is self-consistent in that it is the same as obtained by the analysis of synthetic seismograms using the inferred Q-values. Inferred Qp and Qs values are more than three times higher than previous estimates and imply that unconsolidated sediments of the embayment do not significantly attenuate small-strain earthquake ground motions. These estimates represent a lower bound to Q of the sediments since significant scattering is observed in the waveform data that contributes to the distance decay of wave amplitude. Higher Q values also imply that the unconsolidated sediments of the embayment will form an efficient wave guide for surface waves radiated from shallow earthquakes or large earthquakes that rupture into the sediments, producing high-amplitude, long-duration wave trains that should be considered in earthquake hazard assessments.

  11. Systemic Synthesis Questions [SSynQs] as Tools to Help Students to Build Their Cognitive Structures in a Systemic Manner

    ERIC Educational Resources Information Center

    Hrin, Tamara N.; Fahmy, Ameen F. M.; Segedinac, Mirjana D.; Milenkovic, Dušica D.

    2016-01-01

    Many studies dedicated to the teaching and learning of organic chemistry courses have emphasized that high school students have shown significant difficulties in mastering the concepts of this discipline. Therefore, the aim of our study was to help students to overcome these difficulties by applying systemic synthesis questions, [SSynQs], as the…

  12. QS-21 enhances the early antibody response to oil adjuvant foot-and-mouth disease vaccine in cattle

    PubMed Central

    2016-01-01

    Purpose One of the most important tools against foot-and-mouth disease, a highly contagious and variable viral disease of cloven-hoofed animals, is vaccination. However, the effectiveness of foot-and-mouth disease vaccines on slowing the spread of the disease is questionable. In contrast, high potency vaccines providing early protection may solve issues with the spread of the disease, escaping mutants, and persistency. To increase the potency of the vaccine, additives such as saponin and aluminium hydroxide are used. However, the use of saponin with an oil adjuvant is not common and is sometimes linked to toxicity. QS-21, which is less toxic than Quil A, has been presented as an alternative for use with saponin. In this study, the addition of QS-21 to a commercially available foot-and-mouth disease water-in-oil-in-water emulsion vaccine was evaluated in cattle. Materials and Methods After vaccination, serum samples were collected periodically over 3 months. Sera of the QS-21 and normal oil vaccine groups were compared via serum virus neutralization antibody titre and liquid phase blocking enzyme-linked immunosorbent assay antibody titre. Results The results showed that there was a significant early antibody increase in the QS-21 group. Conclusion Strong early virus neutralizing antibody response will be useful for emergency or ring vaccinations against foot-and-mouth disease in target animals. PMID:27489804

  13. Serum influences the expression of Pseudomonas aeruginosa quorum-sensing genes and QS-controlled virulence genes during early and late stages of growth

    PubMed Central

    Kruczek, Cassandra; Qaisar, Uzma; Colmer-Hamood, Jane A; Hamood, Abdul N

    2014-01-01

    In response to diverse environmental stimuli at different infection sites, Pseudomonas aeruginosa, a serious nosocomial pathogen, coordinates the production of different virulence factors through a complicated network of the hierarchical quorum-sensing (QS) systems including the las, rhl, and the 2-alkyl-4-quinolone-related QS systems. We recently showed that at early stages of growth serum alters the expression of numerous P. aeruginosa genes. In this study, we utilized transcriptional analysis and enzyme assays to examine the effect of serum on the QS and QS-controlled virulence factors during early and late phases of growth of the P. aeruginosa strain PAO1. At early phase, serum repressed the transcription of lasI, rhlI, and pqsA but not lasR or rhlR. However, at late phase, serum enhanced the expression of all QS genes. Serum produced a similar effect on the synthesis of the autoinducers 3OC12-HSL, C4-HSL, and HHQ/PQS. Additionally, serum repressed the expression of several QS-controlled genes in the early phase, but enhanced them in the late phase. Furthermore, serum influenced the expression of different QS-positive (vqsR, gacA, and vfr) as well as QS-negative (rpoN, qscR, mvaT, and rsmA) regulatory genes at either early or late phases of growth. However, with the exception of PAOΔvfr, we detected comparable levels of lasI/lasR expression in PAO1 and PAO1 mutants defective in these regulatory genes. At late stationary phase, serum failed to enhance lasI/lasR expression in PAOΔvfr. These results suggest that depending on the phase of growth, serum differentially influenced the expression of P. aeruginosa QS and QS-controlled virulence genes. In late phase, serum enhanced the expression of las genes through vfr. PMID:24436158

  14. QsMYB1 expression is modulated in response to heat and drought stresses and during plant recovery in Quercus suber.

    PubMed

    Almeida, Tânia; Pinto, Glória; Correia, Barbara; Santos, Conceição; Gonçalves, Sónia

    2013-12-01

    Cork oak is an economically important forest species showing a great tolerance to high temperatures and shortage of water. However, the mechanisms underlying this plasticity are still poorly understood. Among the stress regulators, transcription factors (TFs) are especially important since they can control a wide range of stress-inducible genes, which make them powerful targets for genetic engineering of stress tolerance. Here we evaluated the influence of increasing temperatures (up to 55 °C) or drought (18% field capacity, FC) on the expression profile of an R2R3-MYB transcription factor of cork oak, the QsMYB1. QsMYB1 was previously identified as being preferentially expressed in cork tissues and as having an associated alternative splicing mechanism, which results in two different transcripts (QsMYB1.1 and QsMYB1.2). Expression analysis by reverse transcription quantitative PCR (RT-qPCR) revealed that increasing temperatures led to a gradual down-regulation of QsMYB1 transcripts with more effect on QsMYB1.1 abundance. On the other hand, under drought condition, expression of QsMYB1 variants, mainly the QsMYB1.2, was transiently up-regulated shortly after the stress imposition. Recovery from each stress has also resulted in a differential response by both QsMYB1 transcripts. Several physiological and biochemical parameters (plant water status, chlorophyll fluorescence, lipid peroxidation and proline content) were determined in order to monitor the plant performance under stress and recovery. In conclusion, this report provides the first evidence that QsMYB1 TF may have a putative function in the regulatory network of cork oak response to heat and drought stresses and during plant recovery.

  15. Potent response of QS-21 as a vaccine adjuvant in the skin when delivered with the Nanopatch, resulted in adjuvant dose sparing

    PubMed Central

    Ng, Hwee-Ing; Fernando, Germain J. P.; Depelsenaire, Alexandra C. I.; Kendall, Mark A. F.

    2016-01-01

    Adjuvants play a key role in boosting immunogenicity of vaccines, particularly for subunit protein vaccines. In this study we investigated the induction of antibody response against trivalent influenza subunit protein antigen and a saponin adjuvant, QS-21. Clinical trials of QS-21 have demonstrated the safety but, also a need of high dose for optimal immunity, which could possibly reduce patient acceptability. Here, we proposed the use of a skin delivery technology – the Nanopatch – to reduce both adjuvant and antigen dose but also retain its immune stimulating effects when compared to the conventional needle and syringe intramuscular (IM) delivery. We have demonstrated that Nanopatch delivery to skin requires only 1/100th of the IM antigen dose to induce equivalent humoral response. QS-21 enhanced humoral response in both skin and muscle route. Additionally, Nanopatch has demonstrated 30-fold adjuvant QS-21 dose sparing while retaining immune stimulating effects compared to IM. QS-21 induced localised, controlled cell death in the skin, suggesting that the danger signals released from dead cells contributed to the enhanced immunogenicity. Taken together, these findings demonstrated the suitability of reduced dose of QS-21 and the antigen using the Nanopatch to enhance humoral responses, and the potential to increase patient acceptability of QS-21 adjuvant. PMID:27404789

  16. Potent response of QS-21 as a vaccine adjuvant in the skin when delivered with the Nanopatch, resulted in adjuvant dose sparing.

    PubMed

    Ng, Hwee-Ing; Fernando, Germain J P; Depelsenaire, Alexandra C I; Kendall, Mark A F

    2016-07-11

    Adjuvants play a key role in boosting immunogenicity of vaccines, particularly for subunit protein vaccines. In this study we investigated the induction of antibody response against trivalent influenza subunit protein antigen and a saponin adjuvant, QS-21. Clinical trials of QS-21 have demonstrated the safety but, also a need of high dose for optimal immunity, which could possibly reduce patient acceptability. Here, we proposed the use of a skin delivery technology - the Nanopatch - to reduce both adjuvant and antigen dose but also retain its immune stimulating effects when compared to the conventional needle and syringe intramuscular (IM) delivery. We have demonstrated that Nanopatch delivery to skin requires only 1/100(th) of the IM antigen dose to induce equivalent humoral response. QS-21 enhanced humoral response in both skin and muscle route. Additionally, Nanopatch has demonstrated 30-fold adjuvant QS-21 dose sparing while retaining immune stimulating effects compared to IM. QS-21 induced localised, controlled cell death in the skin, suggesting that the danger signals released from dead cells contributed to the enhanced immunogenicity. Taken together, these findings demonstrated the suitability of reduced dose of QS-21 and the antigen using the Nanopatch to enhance humoral responses, and the potential to increase patient acceptability of QS-21 adjuvant.

  17. Development and Psychometric Validation of the EDE-QS, a 12 Item Short Form of the Eating Disorder Examination Questionnaire (EDE-Q)

    PubMed Central

    Gideon, Nicole; Hawkes, Nick; Mond, Jonathan; Saunders, Rob; Tchanturia, Kate; Serpell, Lucy

    2016-01-01

    Objective The aim of this study was to develop and validate a short form of the Eating Disorder Examination Questionnaire (EDE-Q) for routine, including session by session, outcome assessment. Method The current, 28-item version (6.0) of the EDE-Q was completed by 489 individuals aged 18–72 with various eating disorders recruited from three UK specialist eating disorder services. Rasch analysis was carried out on factors identified by means of principal component analysis, which in combination with expert ratings informed the development of an EDE-Q short form. The shortened questionnaire’s reliability, validity and sensitivity was assessed based on online data collected from students of a UK university and volunteers with a history of eating disorders recruited from a national eating disorders charity aged 18–74 (N = 559). Results A 12-item short form, the Eating Disorder Examination Questionnaire Short (EDE-QS) was derived. The new measure showed high internal consistency (Cronbach’s α = .913) and temporal stability (ICC = .93; p < .001). It was highly correlated with the original EDE-Q (r = .91 for people without ED; r = .82 for people with ED) and other measures of eating disorder and comorbid psychopathology. It was sufficiently sensitive to distinguish between people with and without eating disorders. Discussion The EDE-QS is a brief, reliable and valid measure of eating disorder symptom severity that performs similarly to the EDE-Q and that lends itself for the use of sessional outcome monitoring in treatment and research. PMID:27138364

  18. Production of autoinducer-2 by aerobic endospore-forming bacteria isolated from the West African fermented foods.

    PubMed

    Qian, Yang; Kando, Christine Kere; Thorsen, Line; Larsen, Nadja; Jespersen, Lene

    2015-11-01

    Autoinducer-2 (AI-2) is a quorum-sensing (QS) molecule which mediates interspecies signaling and affects various bacterial behaviors in food fermentation. Biosynthesis of AI-2 is controlled by S-ribosylhomocysteine lyase encoded by the luxS gene. The objective of this study was to investigate production of AI-2 by aerobic endospore-forming bacteria (AEB) isolated from the West African alkaline fermented seed products Mantchoua and Maari. The study included 13 AEB strains of Bacillus subtilis, B. cereus, B. altitudinis, B. amyloliquefaciens, B. licheniformis, B. aryabhattai, B. safensis, Lysinibacillus macroides and Paenibacillus polymyxa. All the tested strains harbored the luxS gene and all strains except for P. polymyxa B314 were able to produce AI-2 during incubation in laboratory medium. Production of AI-2 by AEB was growth phase dependent, showing maximum activity at the late exponential phase. AI-2 was depleted from the culture medium at the beginning of the stationary growth phase, indicating that the tested AEB possess a functional AI-2 receptor that internalizes AI-2. This study provides the evidences of QS system in Bacillus spp. and L. macroides and new knowledge of AI-2 production by AEB. This knowledge contributes to the development of QS-based strategies for better control of alkaline fermentation.

  19. Developmental validation of QIAGEN Investigator(®) 24plex QS Kit and Investigator(®) 24plex GO! Kit: Two 6-dye multiplex assays for the extended CODIS core loci.

    PubMed

    Kraemer, Melanie; Prochnow, Anke; Bussmann, Michael; Scherer, Mario; Peist, Ralf; Steffen, Carolyn

    2017-03-12

    The original CODIS database based on 13 core STR loci has been overwhelmingly successful for matching suspects with evidence. In order to increase the power of discrimination, reduce the possibility of adventitious matches, and expand global data sharing, the CODIS Core Loci Working Group determined the expansion of the CODIS core loci to 20 STR plus three additional "highly recommended" loci (SE33, DY391, Amelogenin) Hares, 2015, 2012 [1,2]. The QIAGEN Investigator 24plex QS and Investigator 24plex GO! Kits are 6-dye multiplex assays that contain all markers of the expanded 23 CODIS core loci along with a unique internal performance control that is co-amplified with the STR markers. The "Quality Sensor" generates additional information for quality control and performance checks. Investigator 24plex QS is designed for purified DNA from casework and reference samples, whereas 24plex GO! is dedicated to direct amplification of reference samples, like blood or buccal cells on FTA or swabs. A developmental validation study was performed on both assays. Here, we report the results of this study which followed the recommendations of the European Network of Forensic Science Institutes (ENFSI) [3] and the Revised Validation Guidelines of the Scientific Working Group on DNA Analysis Methods (SWGDAM) [4]. Data included are for PCR-based procedures e.g. reaction conditions, effects of PCR annealing temperature variations, amplification cycles or cyclers, sensitivity (also in the context of the Quality Sensor), performance with simulated inhibition, stability and efficiency, precision, reproducibility, mixture study, concordance, stutter, species specificity, and case-type samples. The validation results demonstrate that the Investigator 24plex QS and Investigator 24plex GO! Kits are robust and reliable identification assays as required for forensic DNA typing in forensic casework analysis and databasing.

  20. High-resolution Vp, Vp/Vs, Qp and Qs models in the Three Gorges reservoir area, China

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Zhao, C.

    2011-12-01

    The Three Gorges Dam, located in Hubei province in the central China over the Yangtze River, is the world's largest capacity hydroelectric power station with a total generating capacity of 18,200 MW. Since the water impounding in June of 2003, more than thousands of small earthquakes have occurred around the area. For the purpose of investigating the influence of the reservoir impounding on the structure of the reservoir area, we obtained high-resolution 3-D Vp, Vp/Vs ratio, as well as the 3-D attenuation structure of Qp and Qs tomography images. The database of this study is composed of 4967 events recorded on 50 permanent and temporary seismometers, over the period from March, 2009 to June, 2010. After data selection on the basis of spatial distribution and quality, we used the following data sets: 1685 events and 27457 picks for Vp inversion, 1689 events and 27524 picks for Vp/Vs inversion, 2598 events and 24685 t* measurements for the Qp inversion, and 3921 events and 33579 t* measurements for the Qs inversion, respectively. The tomographic resolution was evaluated by restoring tests and the spreading values tests. The preliminary 3-D Vp, Vp/Vs, Qp and Qs results at depths of 0~10 km show significant heterogeneity in the Three Gorges reservoir area, suggesting the complexity of the media in the area. Remarkably low-Vp, high-Vp/Vs, low-Qp and low-Qs anomalies are observed at shallow depths along main rivers, indicating obvious influence on the media structure associated with fluid infiltration. The results of velocity and attenuation tomography indicate that the infiltrating depth of water may reach about 6 km under the convergence of the Yangtze, Xiangxi , Jiuwanxi, and Yandu Rivers, and the depth is about 2 km under Badong region in the upstream of the Yangtze River. In the dam area, there are prominently high-Vp, low-Vp/Vs, and high-Q, suggesting that the fluid infiltration has little influence on the dam. This research is supported by National Key Technology

  1. What radiologists need to know about the pulmonary-systemic flow ratio (Qp/Qs): what it is, how to calculate it, and what it is for.

    PubMed

    Marín Rodríguez, C; Sánchez Alegre, M L; Lancharro Zapata, Á; Alarcón Rodríguez, J

    2015-01-01

    Cardiac magnetic resonance imaging (cMRI) provides abundant morphological and functional information in the study of congenital heart disease. The functional information includes pulmonary output and systemic output; the ratio between these two (Qp/Qs) is the shunt fraction. After birth, in normal conditions the pulmonary output is practically identical to the systemic output, so Qp/Qs = 1. In patients with « shunts » between the systemic and pulmonary circulations, the ratio changes, and the interpretation of these findings varies in function of the location of the shunt (intracardiac or extracardiac) and of the associated structural or postsurgical changes. We review the concept of Qp/Qs; the methods to calculate it, with special emphasis on cMRI; and the meaning of the results obtained. We place special emphasis on the relevance of these findings depending on the underlying disease and the treatment the patient has undergone.

  2. Novel Reporter for Identification of Interference with Acyl Homoserine Lactone and Autoinducer-2 Quorum Sensing

    PubMed Central

    Weiland-Bräuer, Nancy; Pinnow, Nicole

    2014-01-01

    Two reporter strains were established to identify novel biomolecules interfering with bacterial communication (quorum sensing [QS]). The basic design of these Escherichia coli-based systems comprises a gene encoding a lethal protein fused to promoters induced in the presence of QS signal molecules. Consequently, these E. coli strains are unable to grow in the presence of the respective QS signal molecules unless a nontoxic QS-interfering compound is present. The first reporter strain designed to detect autoinducer-2 (AI-2)-interfering activities (AI2-QQ.1) contained the E. coli ccdB lethal gene under the control of the E. coli lsrA promoter. The second reporter strain (AI1-QQ.1) contained the Vibrio fischeri luxI promoter fused to the ccdB gene to detect interference with acyl-homoserine lactones. Bacteria isolated from the surfaces of several marine eukarya were screened for quorum-quenching (QQ) activities using the established reporter systems AI1-QQ.1 and AI2-QQ.1. Out of 34 isolates, two interfered with acylated homoserine lactone (AHL) signaling, five interfered with AI-2 QS signaling, and 10 were demonstrated to interfere with both signal molecules. Open reading frames (ORFs) conferring QQ activity were identified for three selected isolates (Photobacterium sp., Pseudoalteromonas sp., and Vibrio parahaemolyticus). Evaluation of the respective heterologously expressed and purified QQ proteins confirmed their ability to interfere with the AHL and AI-2 signaling processes. PMID:25527543

  3. Isoliensinine induces dephosphorylation of NF-κB p65 subunit at Ser536 via a PP2A-dependent mechanism in hepatocellular carcinoma cells: roles of impairing PP2A/I2PP2A interaction

    PubMed Central

    Shu, Guangwen; Zhang, Lang; Jiang, Shanqing; Cheng, Zhuo; Wang, Guan; Huang, Xu; Yang, Xinzhou

    2016-01-01

    Our previous study discovered that isoliensinine (isolie) triggers hepatocellular carcinoma (HCC) cell apoptosis via inducing p65 dephosphorylation at Ser536 and inhibition of NF-κB. Here, we showed that isolie promoted p65/PP2A interaction in vitro and in vivo. Repression of PP2A activity or knockdown of the expression of PP2A-C (the catalytic subunit of PP2A) abrogated isolie-provoked p65 dephosphorylation. I2PP2A is an endogenous PP2A inhibitor. Isolie directly impaired PP2A/I2PP2A interaction. Knockdown of I2PP2A boosted p65/PP2A association and p65 dephosphorylation. Overexpression of I2PP2A restrained isolie-induced p65 dephosphorylation. Untransformed hepatocytes were insensitive to isolie-induced NF-κB inhibition and cell apoptosis. In these cells, basal levels of I2PP2A and p65 phosphorylation at Ser536 were lower than in HCC cells. These findings collectively indicated that isolie suppresses NF-κB in HCC cells through impairing PP2A/I2PP2A interaction and stimulating PP2A-dependent p65 dephosphorylation at Ser536. PMID:27244888

  4. Isoliensinine induces dephosphorylation of NF-kB p65 subunit at Ser536 via a PP2A-dependent mechanism in hepatocellular carcinoma cells: roles of impairing PP2A/I2PP2A interaction.

    PubMed

    Shu, Guangwen; Zhang, Lang; Jiang, Shanqing; Cheng, Zhuo; Wang, Guan; Huang, Xu; Yang, Xinzhou

    2016-06-28

    Our previous study discovered that isoliensinine (isolie) triggers hepatocellular carcinoma (HCC) cell apoptosis via inducing p65 dephosphorylation at Ser536 and inhibition of NF-κB. Here, we showed that isolie promoted p65/PP2A interaction in vitro and in vivo. Repression of PP2A activity or knockdown of the expression of PP2A-C (the catalytic subunit of PP2A) abrogated isolie-provoked p65 dephosphorylation. I2PP2A is an endogenous PP2A inhibitor. Isolie directly impaired PP2A/I2PP2A interaction. Knockdown of I2PP2A boosted p65/PP2A association and p65 dephosphorylation. Overexpression of I2PP2A restrained isolie-induced p65 dephosphorylation. Untransformed hepatocytes were insensitive to isolie-induced NF-κB inhibition and cell apoptosis. In these cells, basal levels of I2PP2A and p65 phosphorylation at Ser536 were lower than in HCC cells. These findings collectively indicated that isolie suppresses NF-κB in HCC cells through impairing PP2A/I2PP2A interaction and stimulating PP2A-dependent p65 dephosphorylation at Ser536.

  5. Cloning and characterization of the Streptomyces peucetius dnrQS genes encoding a daunosamine biosynthesis enzyme and a glycosyl transferase involved in daunorubicin biosynthesis.

    PubMed Central

    Otten, S L; Liu, X; Ferguson, J; Hutchinson, C R

    1995-01-01

    The dnrQS genes from the daunorubicin producer Streptomyces peucetius were characterized by DNA sequencing, complementation analysis, and gene disruption. The dnrQ gene is required for daunosamine biosynthesis, and dnrS appears to encode a glycosyltransferase for the addition of the 2,3,6-trideoxy-3-aminohexose, daunosamine, to epsilon-rhodomycinone. PMID:7592454

  6. The Variation of Universally Acknowledged World-Class Universities (UAWCUs) between 2010 and 2015: An Empirical Study by the Ranks of THEs, QS and ARWU

    ERIC Educational Resources Information Center

    Liu, Lu; Liu, Zhimin

    2016-01-01

    Due to certainty recognition in ranking systems, the commonly included top 100 universities are regarded as the Universally Acknowledged World-Class Universities (UAWCUs). From three university rankings-THEs, QS and ARWU from 2010 to 2015, the following conclusions can be drawn from this study: Firstly, 56 universities are commonly ranked in the…

  7. Cinnamaldehyde and cinnamaldehyde derivatives reduce virulence in Vibrio spp. by decreasing the DNA-binding activity of the quorum sensing response regulator LuxR

    PubMed Central

    Brackman, Gilles; Defoirdt, Tom; Miyamoto, Carol; Bossier, Peter; Van Calenbergh, Serge; Nelis, Hans; Coenye, Tom

    2008-01-01

    Background To date, only few compounds targeting the AI-2 based quorum sensing (QS) system are known. In the present study, we screened cinnamaldehyde and substituted cinnamaldehydes for their ability to interfere with AI-2 based QS. The mechanism of QS inhibition was elucidated by measuring the effect on bioluminescence in several Vibrio harveyi mutants. We also studied in vitro the ability of these compounds to interfere with biofilm formation, stress response and virulence of Vibrio spp. The compounds were also evaluated in an in vivo assay measuring the reduction of Vibrio harveyi virulence towards Artemia shrimp. Results Our results indicate that cinnamaldehyde and several substituted derivatives interfere with AI-2 based QS without inhibiting bacterial growth. The active compounds neither interfered with the bioluminescence system as such, nor with the production of AI-2. Study of the effect in various mutants suggested that the target protein is LuxR. Mobility shift assays revealed a decreased DNA-binding ability of LuxR. The compounds were further shown to (i) inhibit biofilm formation in several Vibrio spp., (ii) result in a reduced ability to survive starvation and antibiotic treatment, (iii) reduce pigment and protease production in Vibrio anguillarum and (iv) protect gnotobiotic Artemia shrimp against virulent Vibrio harveyi BB120. Conclusion Cinnamaldehyde and cinnamaldehyde derivatives interfere with AI-2 based QS in various Vibrio spp. by decreasing the DNA-binding ability of LuxR. The use of these compounds resulted in several marked phenotypic changes, including reduced virulence and increased susceptibility to stress. Since inhibitors of AI-2 based quorum sensing are rare, and considering the role of AI-2 in several processes these compounds may be useful leads towards antipathogenic drugs. PMID:18793453

  8. Screening for N-AHSL-Based-Signaling Interfering Enzymes.

    PubMed

    Uroz, Stéphane; Oger, Phil M

    2017-01-01

    Quorum sensing (QS)-based signaling is a widespread pathway used by bacteria for the regulation of functions involved in their relation to the environment or their host. QS relies upon the production, accumulation and perception of small diffusable molecules by the bacterial population, hence linking high gene expression with high cell population densities. Among the different QS signal molecules, an important class of signal molecules is the N-acyl homoserine lactone (N-AHSL). In pathogens such as Erwinia or Pseudomonas, N-AHSL based QS is crucial to overcome the host defenses and ensure a successful infection. Interfering with QS-regulation allows the algae Delisea pulcra to avoid surface colonization by bacteria. Thus, interfering the QS-regulation of pathogenic bacteria is a promising antibiotic-free antibacterial therapeutic strategy. To date, two N-AHSL lactonases and one amidohydrolase families of N-ASHL degradation enzymes have been characterized and have proven to be efficient in vitro to control N-AHSL-based QS-regulated functions in pathogens. In this chapter, we provide methods to screen individual clones or bacterial strains as well as pool of clones for genomic and metagenomic libraries, that can be used to identify strains or clones carrying N-ASHL degradation enzymes.

  9. Silicate liquid immiscibility in magmas and in the system K2O-FeO-AI2O3-SiO2: an example of serendipity

    USGS Publications Warehouse

    Roedder, E.

    1978-01-01

    The concept of silicate liquid immiscibility was invoked early in the history of petrology to explain certain pairs of compositionally divergent rocks, but. as a result of papers by Greig (Am. J. Sci. 13, 1-44, 133-154) and Bowen (The Evolution of the Igneous Rocks), it fell into disfavor for many years. The discovery of immiscibility in geologically reasonable temperature ranges and compositions in experimental work on the system K2O-FeO-Al2O3-SiO2, and of evidence for immiscibility in a variety of lunar and terrestrial rocks, has reinstated the process. Phase equilibria in the high-silica corner of the tetrahedron representing the system K2O- FeO-Al2O3-SiO2 are presented, in the form of constant FeO sections through the tetrahedron, at 10% increments. Those sections, showing the tentative relationships of the primary phase volumes, are based on 5631 quenching runs on 519 compositions, made in metallic iron containers in pure nitrogen. Thirteen crystalline compounds are involved, of which at least six show two or more crystal modifica-tions. Two separate phase volumes, in each of which two immiscible liquids, one iron-rich and the other iron-poor, are present at the liquidus. One of these volumes is entirely within the quaternary system, astride the 1:1 K2O:Al2O3 plane. No quaternary compounds as such have been found, but evidence does point toward at least partial quaternary solid solution, with rapidly lowering liquidus temperatures, from K2O??Al2O3?? 2SiO2 ('potash nepheline', kalsilite. kaliophilite) to the isostructural compound K2O??FeO??3SiO2, and from K2O??Al2O3??4SiO2 (leucite) to the isostructural compound K2O??FeO??5SiO2, Both of these series apparently involve substitution, in tetrahedral coordination. of a ferrous iron and a silicon ion for two aluminum ions. Some of the 'impurities' found in analyses of the natural phases may reflect these substitutions. As a result of the geometry of the immiscibility volume located entirely within the quaternary

  10. Acyl-homoserine lactone-based quorum sensing and quorum quenching hold promise to determine the performance of biological wastewater treatments: An overview.

    PubMed

    Huang, Jinhui; Shi, Yahui; Zeng, Guangming; Gu, Yanling; Chen, Guiqiu; Shi, Lixiu; Hu, Yi; Tang, Bi; Zhou, Jianxin

    2016-08-01

    Quorum sensing (QS) is a communication process between cells, in which bacteria secrete and sense the specific chemicals, and regulate gene expression in response to population density. Quorum quenching (QQ) blocks QS system, and inhibits gene expression mediating bacterial behaviors. Given the extensive research of acyl-homoserine lactone (AHL) signals, existences and effects of AHL-based QS and QQ in biological wastewater treatments are being subject to high concern. This review summarizes AHL structure, synthesis mode, degradation mechanisms, analytical methods, environmental factors, AHL-based QS and QQ mechanisms. The existences and roles of AHL-based QS and QQ in biomembrane processes, activated sludge processes and membrane bioreactors are summarized and discussed, and corresponding exogenous regulation strategy by selective enhancement of AHL-based QS or QQ coexisting in biological wastewater treatments is suggested. Such strategies including the addition of AHL signals, AHL-producing bacteria as well as quorum quenching enzyme or bacteria can effectively improve wastewater treatment performance without killing or limiting bacterial survival and growth. This review will present the theoretical and practical cognition for bacterial AHL-based QS and QQ, suggest the feasibility of exogenous regulation strategies in biological wastewater treatments, and provide useful information to scientists and engineers who work in this field.

  11. An investigation of structural parameters and magnetic and optical properties of EuLn{sub 2}Q{sub 4} (Ln=Tb-Lu, Q=S, Se)

    SciTech Connect

    Jin Gengbang; Choi, Eun Sang; Guertin, Robert P.; Albrecht-Schmitt, Thomas E.

    2008-01-15

    EuLn{sub 2}Q{sub 4} (Ln=Tb-Lu; Q=S, Se) has been synthesized using Sb{sub 2}Q{sub 3} (Q=S, Se) fluxes at 1000 deg. C. These compounds crystallize in a CaFe{sub 2}O{sub 4}-type three-dimensional channel structure that is built from edge-shared double rutile chains of [LnQ{sub 6}] octahedra running down the b-axis. Each double chain is connected at the vertices to four other double chains to form open channels where bicapped trigonal prismatic Eu{sup 2+} ions reside. All of these compounds show antiferromagnetic ordering with Neel temperatures, T{sub N}{approx}3-4 K. The optical band gaps for EuTb{sub 2}Se{sub 4}, EuDy{sub 2}Se{sub 4}, EuHo{sub 2}Se{sub 4}, EuEr{sub 2}Se{sub 4}, EuTm{sub 2}Se{sub 4}, EuYb{sub 2}Se{sub 4} EuLu{sub 2}Se{sub 4}, and EuYb{sub 2}S{sub 4} are found to be 2.0, 1.8, 1.8, 1.7, 1.8, 1.3, 1.7, and 1.6 eV, respectively. - Graphical abstract: A view of the three-dimensional channel structure of EuYb{sub 2}S{sub 4} down the b-axis.

  12. Sintering oxide ceramics based on AI2O3 and ZrO2, activated by MgO, TiO2 and SiO2 additives

    NASA Astrophysics Data System (ADS)

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.

    2016-11-01

    The positive effect of the addition of MgO and TiO2 in an amount of no more than 1 wt. % on sintering and physico-mechanical properties of alumina ceramics is established. Addition of 5% of SiO2 to A12O3 provides the mechanism of liquid phase sintering of ceramics, which leads to increase in its density and strength up to 480 MPa. In ceramic system A12O3 - ZrO2 - Y2O3 highest level of physical and mechanical properties of the composition had a hypereutectic composition 16.6% A12O3 - 76% Z1O2 - 7.4% Y2O3. In this composition two mechanisms of hardening are realized simultaneously, such as transformational hardening by t- m - ZrO2 transition and dispersion strengthening with high-modulus particles of α- A12O3.

  13. Blue foot: a second case of "tattoo blow-out" pigment spread successfully treated with the QS-Nd:YAG laser.

    PubMed

    Khetarpal, Shilpi; Molenda, Matthew; Seiger, Eric; Pui, John; Obagi, Suzan

    2010-11-01

    The "tattoo blow-out" phenomenon occurs when tattoo pigments spread outside the border of a tattoo. It is thought to occur when ink is injected too deeply. A healthy 36-year-old female presented to a dermatologist with diffuse spread of tattoo pigment outside the original tattoo that occurred within one day of the placement of a professional tattoo on the dorsum of her foot. The patient was seeking treatment six weeks after the tattoo was placed because she thought the discoloration would improve or resolve on its own, but it worsened. Two punch biopsies were obtained for histology. The biopsy results confirmed granular black pigment consistent with a tattoo in the dermis and subcutaneous fat. The location of pigment was deeper than expected. Due to the success of the QS-Nd:YAG laser in a prior patient, the same treatment was recommended for this patient. The patient received nine laser sessions using the Q-switched laser at 1064 nm, 4 mm, 10 Hz, with gradually increasing energy from 4.5 to 6.0 J/cm2. The pigment outside of the original tattoo borders faded and is barely perceptible. It is important that physicians be made aware of tattoo complications so they can advise patients in regards to the associated risks.

  14. A chemical biology approach to interrogate quorum-sensing regulated behaviors at the molecular and cellular level.

    PubMed

    Lowery, Colin A; Matamouros, Susana; Niessen, Sherry; Zhu, Jie; Scolnick, Jonathan; Lively, Jenny M; Cravatt, Benjamin F; Miller, Samuel I; Kaufmann, Gunnar F; Janda, Kim D

    2013-07-25

    Small molecule probes have been used extensively to explore biologic systems and elucidate cellular signaling pathways. In this study, we use an inhibitor of bacterial communication to monitor changes in the proteome of Salmonella enterica serovar Typhimurium with the aim of discovering unrecognized processes regulated by AI-2-based quorum-sensing (QS), a mechanism of bacterial intercellular communication that allows for the coordination of gene expression in a cell density-dependent manner. In S. typhimurium, this system regulates the uptake and catabolism of intercellular signals and has been implicated in pathogenesis, including the invasion of host epithelial cells. We demonstrate that our QS antagonist is capable of selectively inhibiting the expression of known QS-regulated proteins in S. typhimurium, thus attesting that QS inhibitors may be used to confirm proposed and elucidate previously unidentified QS pathways without relying on genetic manipulation.

  15. Shear modulus and attenuation Qs of olivine from forced-oscillation measurements under mantle conditions and seismic frequencies

    NASA Astrophysics Data System (ADS)

    Perrillat, J. P.; Le Godec, Y.; Philippe, J.; Bergame, F.; Chambat, F.; Mezouar, N.; Tauzin, B.

    2015-12-01

    Interpretation of seismic profiles and tomographic models of the Earth's mantle requires exploring the viscoelastic behaviour of rocks / minerals at low strains and seismic frequencies. These physical properties can be investigated by cyclic loading experiments that measure the dynamic response of materials to an applied stress. To date, these data were only accessible by torsional forced-oscillation tests performed in gas vessel apparatus and limited to ~ 0.3 GPa. Here, we demonstrate the feasibility of forced-oscillations tests up to the Earth's upper mantle conditions thanks to the development of a torsion module in the Paris-Edinburgh press and the use of X-ray radiation. The experimental device is based on the frame of a V7 Paris-Edinburgh press where both of the two opposed anvils can rotate through two sets of gear reducer and thrust bearings located at the end of each anvil. The accurate rotation of the anvils is monitored by stepper motors and encoders, and enables to apply a low-frequency sinusoidal torque on the cell assembly. The sample and an elastic standard of known modulus and negligible dissipation are loaded in series in a boron-epoxy gasket. The measurement of the relative amplitudes and phases of the torsional mode displacements in standard and sample provides for the determination of the shear modulus and of the strain energy dissipation for the sample. The main challenge in applying the forced-oscillation method at high pressure is the need of a technique for measuring stress and strain with sufficient precision, and with sufficiently short measurement time, while the sample is embedded in the high-pressure vessel. These technical difficulties can be overcome through the use of synchrotron radiation. The strain of the sample is measured in situ and in real-time through X-ray radiography, while the stress is estimated from the strain of the elastic standard (a corundum sample in our case). Hence, coupling the new RoToPEc device with synchrotron

  16. High-temperature order-disorder transitions in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te)

    SciTech Connect

    Kaltzoglou, Andreas; Powell, Anthony V.; Knight, Kevin S.; Vaqueiro, Paz

    2013-02-15

    The temperature dependence of anion ordering in the skutterudites CoGe{sub 1.5}Q{sub 1.5} (Q=S, Te) has been investigated by powder neutron diffraction. Both materials adopt a rhombohedral structure at room temperature (space group R3{sup Macron} ) in which the anions are ordered trans to each other within Ge{sub 2}Q{sub 2} rings. In CoGe{sub 1.5}S{sub 1.5}, anion ordering is preserved up to the melting point of 950 Degree-Sign C. However, rhombohedral CoGe{sub 1.5}Te{sub 1.5} undergoes a phase transition at 610 Degree-Sign C involving a change to cubic symmetry (space group Im3{sup Macron }). In the high-temperature modification, there is a statistical distribution of anions over the available sites within the Ge{sub 2}Te{sub 2} rings. The structural transition involves a reduction in the degree of distortion of the Ge{sub 2}Te{sub 2} rings which progressively transform from a rhombus to a rectangular shape. The effect of this transition on the thermoelectric properties has been investigated. - Graphical abstract: Powder neutron diffraction reveals that the skutterudite CoGe{sub 1.5}Te{sub 1.5} undergoes a phase transition at 610 Degree-Sign C, involving the disordering of the anions within the Ge{sub 2}Te{sub 2} rings. Highlights: Black-Right-Pointing-Pointer CoGe{sub 1.5}S{sub 1.5} retains an ordered skutterudite structure up to 950 Degree-Sign C. Black-Right-Pointing-Pointer CoGe{sub 1.5}Te{sub 1.5} undergoes an order-disorder phase transition at 610 Degree-Sign C. Black-Right-Pointing-Pointer Below 610 Degree-Sign C, anions are arranged trans to each other within Ge{sub 2}Te{sub 2} rings. Black-Right-Pointing-Pointer Above 610 Degree-Sign C, anions are statistically distributed within the Ge{sub 2}Te{sub 2} rings. Black-Right-Pointing-Pointer The effect of the phase transition on the thermal conductivity is discussed.

  17. Final Report - Glass Formulation Development and Testing for DWPF High AI2O3 HLW Sludges, VSL-10R1670-1, Rev. 0, dated 12/20/10

    SciTech Connect

    Kruger, Albert A.; Pegg, I. L.; Kot, W. K.; Gan, H.; Matlack, K. S.

    2013-11-13

    The principal objective of the work described in this Final Report is to develop and identify glass frit compositions for a specified DWPF high-aluminum based sludge waste stream that maximizes waste loading while maintaining high production rate for the waste composition provided by ORP/SRS. This was accomplished through a combination of crucible-scale, vertical gradient furnace, and confirmation tests on the DM100 melter system. The DM100-BL unit was selected for these tests. The DM100-BL was used for previous tests on HLW glass compositions that were used to support subsequent tests on the HLW Pilot Melter. It was also used to process compositions with waste loadings limited by aluminum, bismuth, and chromium, to investigate the volatility of cesium and technetium during the vitrification of an HLW AZ-102 composition, to process glass formulations at compositional and property extremes, and to investigate crystal settling on a composition that exhibited one percent crystals at 963{degrees}C (i.e., close to the WTP limit). The same melter was selected for the present tests in order to maintain comparisons between the previously collected data. The tests provide information on melter processing characteristics and off-gas data, including formation of secondary phases and partitioning. Specific objectives for the melter tests are as follows: Determine maximum glass production rates without bubbling for a simulated SRS Sludge Batch 19 (SB19). Demonstrate a feed rate equivalent to 1125 kg/m{sup 2}/day glass production using melt pool bubbling. Process a high waste loading glass composition with the simulated SRS SB19 waste and measure the quality of the glass product. Determine the effect of argon as a bubbling gas on waste processing and the glass product including feed processing rate, glass redox, melter emissions, etc.. Determine differences in feed processing and glass characteristics for SRS SB19 waste simulated by the co-precipitated and direct

  18. Comparison of the artus HIV-1 QS-RGQ and VERSANT HIV-1 RNA 1.0 assays for quantitative detection of human immunodeficiency virus type 1 in plasma samples.

    PubMed

    Dvir, Roee; Canducci, Filippo; Racca, Sara; Rolla, Serena; Stucchi, Sonia; Clementi, Massimo

    2015-07-01

    Several integrated diagnostic platforms to quantify human immunodeficiency virus type-1 viremia have been developed in recent years. We evaluated the performances of the Artus HIV-1 QS-RGQ assay, using the complete QIAsymphony RGQ workflow. 192 clinical plasma specimens and external control panel samples were analyzed, using the Artus assay and the routine Siemens VERSANT HIV-1 RNA 1.0 assay. Three samples were excluded due to amplification inhibition. Among the remaining 189 specimens, 130 samples were detected as positive (above the limit of detection by both assays; median log10 difference: 0.01) and 18 samples were detected as negative. Eight samples (4.2%), all slightly above the limit of detection of the Versant assay, were negative with the Artus assay. The remaining 33 samples (beside 3 negative by Artus assay) were positive by both assays, but below the limit of detection at least in one of them. Results from the external panel samples showed a mean Log10 variation of -0.18 and -0.45 for the Versant and the Artus assays, respectively. As both assays showed highly correlated results, the QIAsymphony RGQ system, using the Artus HIV-1 QS-RGQ assay, could be considered a potential platform for HIV-1 RNA quantification in plasma.

  19. Whole-Cell Biosensors as Tools for the Detection of Quorum-Sensing Molecules: Uses in Diagnostics and the Investigation of the Quorum-Sensing Mechanism.

    PubMed

    O'Connor, Gregory; Knecht, Leslie D; Salgado, Nelson; Strobel, Sebastian; Pasini, Patrizia; Daunert, Sylvia

    2015-10-17

    Genetically engineered bacterial whole-cell biosensors are powerful tools that take advantage of bacterial proteins and pathways to allow for detection of a specific analyte. These biosensors have been employed for a broad range of applications, including the detection of bacterial quorum-sensing molecules (QSMs). Bacterial QSMs are the small molecules bacteria use for population density-dependent communication, a process referred to as quorum sensing (QS). Various research groups have investigated the presence of QSMs, including N-acyl homoserine lactones (AHLs) and autoinducer-2 (AI-2), in physiological samples in attempts to enhance our knowledge of the role of bacteria and QS in disease states. Continued studies in these fields may allow for improved patient care and therapeutics based upon QSMs. Furthermore, bacterial whole-cell biosensors have elucidated the roles of some antibiotics as QS agonists and antagonists. Graphical Abstract.

  20. A study of the scour-fill threshold based on Lane's equilibrium relation: The lower Yellow River

    NASA Astrophysics Data System (ADS)

    Xu, Jiongxin

    2015-12-01

    The scour-fill threshold in river channels is an expression of scour-fill equilibrium, which may be understood as the balance between the river's sediment carrying capability and the sediment load imposed by the drainage basin. In the present study, the above capability-load relation is quantified using Lane's relation, γQJ-QsD50, wherein Q is water discharge, J is channel slope, Qs is sediment transport rate, D50 is median size of bed material, and γ is the specific weight of water. On this basis, we have established scour-fill thresholds for the lower Yellow River based on data from 141 flood events. The results show that the QsD50-γQJ relation may well distinguish between the scour and fill flood events. The following equation has been established: SDRFE = 0.00099(γQJ)0.90(QsD50)- 0.60, wherein SDRFE is channel sediment delivery ratio. From the equation, the scour-fill threshold is established as: QsD50 = 0.00001(γQJ)1.5. Starting from this formula, four possible options are proposed for sediment management of the lower Yellow River.

  1. Programming the quorum sensing-based AND gate in Shewanella oneidensis for logic gated-microbial fuel cells.

    PubMed

    Hu, Yidan; Yang, Yun; Katz, Evgeny; Song, Hao

    2015-03-11

    An AND logic gate based on a synthetic quorum-sensing (QS) module was constructed in a Shewanella oneidensis MR-1 mtrA knockout mutant. The presence of two input signals activated the expression of a periplasmic decaheme cytochrome MtrA to regenerate the extracellular electron transfer conduit, enabling the construction of AND-gated microbial fuel cells.

  2. LuxS-Based Signaling in Streptococcus gordonii: Autoinducer 2 Controls Carbohydrate Metabolism and Biofilm Formation with Porphyromonas gingivalis

    PubMed Central

    McNab, Roderick; Ford, Suzannah K.; El-Sabaeny, Azza; Barbieri, Bruno; Cook, Guy S.; Lamont, Richard J.

    2003-01-01

    Communication based on autoinducer 2 (AI-2) is widespread among gram-negative and gram-positive bacteria, and the AI-2 pathway can control the expression of genes involved in a variety of metabolic pathways and pathogenic mechanisms. In the present study, we identified luxS, a gene responsible for the synthesis of AI-2, in Streptococcus gordonii, a major component of the dental plaque biofilm. S. gordonii conditioned medium induced bioluminescence in an AI-2 reporter strain of Vibrio harveyi. An isogenic mutant of S. gordonii, generated by insertional inactivation of the luxS gene, was unaffected in growth and in its ability to form biofilms on polystyrene surfaces. In contrast, the mutant strain failed to induce bioluminescence in V. harveyi and was unable to form a mixed species biofilm with a LuxS-null strain of the periodontal pathogen Porphyromonas gingivalis. Complementation of the luxS mutation in S. gordonii restored normal biofilm formation with the luxS-deficient P. gingivalis. Differential display PCR demonstrated that the inactivation of S. gordonii luxS downregulated the expression of a number of genes, including gtfG, encoding glucosyltransferase; fruA, encoding extracellular exo-β-d-fructosidase; and lacD encoding tagatose 1,6-diphosphate aldolase. However, S. gordonii cell surface expression of SspA and SspB proteins, previously implicated in mediating adhesion between S. gordonii and P. gingivalis, was unaffected by inactivation of luxS. The results suggest that S. gordonii produces an AI-2-like signaling molecule that regulates aspects of carbohydrate metabolism in the organism. Furthermore, LuxS-dependent intercellular communication is essential for biofilm formation between nongrowing cells of P. gingivalis and S. gordonii. PMID:12486064

  3. Surface coatings that promote rapid release of peptide-based AgrC inhibitors for attenuation of quorum sensing in Staphylococcus aureus.

    PubMed

    Broderick, Adam H; Stacy, Danielle M; Tal-Gan, Yftah; Kratochvil, Michael J; Blackwell, Helen E; Lynn, David M

    2014-01-01

    Staphylococcus aureus is a major human pathogen responsible for a variety of life-threatening infections. The pathogenicity of this organism is attributed to its ability to produce a range of virulence factors and toxins, including the superantigen toxic shock syndrome toxin-1 (TSST-1). While many S. aureus infections can be treated using conventional antibiotics, strains resistant to these bactericidal agents have emerged. Approaches that suppress pathogenicity through mechanisms that are nonbactericidal (i.e., antivirulence approaches) could provide new options for treating infections, including those caused by resistant strains. Here, we report a nonbactericidal approach to suppressing pathogenicity based on the release of macrocyclic peptides (1 and 2) that inhibit the agr quorum sensing (QS) circuit in group-III S. aureus. It is demonstrated that these peptides can be immobilized on planar and complex objects (on glass slides, nonwoven meshes, or within absorbent tampons) using the rapidly dissolving polymer carboxymethylcellulose (CMC). Peptide-loaded CMC films released peptide rapidly (<5 min) and promoted strong (>95%) inhibition of the agr QS circuit without inducing cell death when incubated in the presence of a group-III S. aureus gfp-reporter strain. Peptide 1 is among the most potent inhibitors of QS in S. aureus reported to date, and the group-III QS circuit regulates production of TSST-1, the primary cause of toxic shock syndrome (TSS). These results thus suggest approaches to treat the outer covers of tampons, wound dressings, or other objects to suppress toxin production and reduce the severity of TSS in clinical and personal care contexts. Because peptide 1 also inhibits QS in S. aureus groups-I, -II, and -IV, this approach could also provide a pathway for attenuation of QS and associated virulence phenotypes in a broader range of contexts.

  4. A dynamic method based on the specific substrate uptake rate to set up a feeding strategy for Pichia pastoris

    PubMed Central

    2011-01-01

    Background Pichia pastoris is one of the most important host organisms for the recombinant production of proteins in industrial biotechnology. To date, strain specific parameters, which are needed to set up feeding profiles for fed batch cultivations, are determined by time-consuming continuous cultures or consecutive fed batch cultivations, operated at different parameter sets. Results Here, we developed a novel approach based on fast and easy to do batch cultivations with methanol pulses enabling a more rapid determination of the strain specific parameters specific substrate uptake rate qs, specific productivity qp and the adaption time (Δtimeadapt) of the culture to methanol. Based on qs, an innovative feeding strategy to increase the productivity of a recombinant Pichia pastoris strain was developed. Higher specific substrate uptake rates resulted in increased specific productivity, which also showed a time dependent trajectory. A dynamic feeding strategy, where the setpoints for qs were increased stepwise until a qs max of 2.0 mmol·g-1·h-1 resulted in the highest specific productivity of 11 U·g-1·h-1. Conclusions Our strategy describes a novel and fast approach to determine strain specific parameters of a recombinant Pichia pastoris strain to set up feeding profiles solely based on the specific substrate uptake rate. This approach is generic and will allow application to other products and other hosts. PMID:21371310

  5. Autoinducer-2 controls virulence of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial communication via quorum sensing (QS) has been reported to be important in the production of virulence factors, antibiotic sensitivity, and biofilm development. Three QS systems, known as the autoinducer (AI) - AI-1, AI-2, and AI-3 systems, have been identified previously in the foodborne ...

  6. Autonomous Bacterial Localization and Gene Expression Based on Nearby Cell Receptor Density

    DTIC Science & Technology

    2013-01-22

    density, these cells expressed marker proteins to indicate phenotypic response. Specifically, site-specific synthesis of bacterial quorum sensing ...Escherichia coli; quorum sensing ; synthetic biology Introduction Synthetic biology engenders design-based rewiring of a cell’s genetic circuitry for the...the signal transduction processes of quorum sensing (QS) as a means of inter- and intra-species communication and the coordination of population-based

  7. Magnetic bead-based nucleic acid purification kit: Clinical application and performance evaluation in stool specimens.

    PubMed

    Yoon, Jihoon G; Kang, Jin Seok; Hwang, Seung Yong; Song, Jaewoo; Jeong, Seok Hoon

    2016-05-01

    Two different methods - the semi-automated magnetic bead-based kit (SK, Stool DNA/RNA Purification kit®) and the manual membrane column-based kit (QS, QIAamp® DNA Stool Mini kit) - for purifying nucleic acids from clinical stool samples were compared and evaluated. The SK kit was more user-friendly than QS due to the reduced manual processing, partial automation, and short turnaround time with half cost. Furthermore, SK produced high yields in both DNA and RNA extractions but poor purity in RNA extraction. In the assessment of rotavirus and Clostridium difficile infection, both kits had equivalent or more sensitive performance compared with the standard method. Although SK showed some interference and inhibition in nucleic acid extraction, the performance, including the repeatability, linearity, analytical sensitivity, and matrix effect, was sufficient for routine clinical use.

  8. Autoinducer-2 increases biofilm formation via an ica- and bhp-dependent manner in Staphylococcus epidermidis RP62A.

    PubMed

    Xue, Ting; Ni, Jingtian; Shang, Fei; Chen, Xiaolin; Zhang, Ming

    2015-05-01

    Staphylococcus epidermidis has become the most common cause of nosocomial bacteraemia and the principal organism responsible for indwelling medical device -associated infections. Its pathogenicity is mainly due to its ability to form biofilms on the implanted medical devices. Biofilm formation is a quorum-sensing (QS)-dependent process controlled by autoinducers, which are signalling molecules. Here, we investigated the function of the autoinducer-2 (AI-2) QS system, especially the influence of AI-2 on biofilm formation in S. epidermidis RP62A. Results showed that the addition of AI-2 leads to a significant increase in biofilm formation, in contrast with previous studies which showed that AI-2 limits biofilm formation in Staphylococci. We found that AI-2 increases biofilm formation by enhancing the transcription of the ica operon, which is a known component in the AI-2-regulated biofilm pathway. In addition, we first observed that the transcript level of bhp, which encodes a biofilm-associated protein, was also increased following the addition of AI-2. Furthermore, we found that, among the known biofilm regulator genes (icaR, sigB, rbsU, sarA, sarX, sarZ, clpP, agrA, abfR, arlRS, saeRS), only icaR can be regulated by AI-2, suggesting that AI-2 may regulate biofilm formation by an icaR-dependent mechanism in S. epidermidis RP62A.

  9. Quorum Sensing Desynchronization Leads to Bimodality and Patterned Behaviors

    PubMed Central

    Quan, David N.; Tsao, Chen-Yu; Wu, Hsuan-Chen; Bentley, William E.

    2016-01-01

    Quorum Sensing (QS) drives coordinated phenotypic outcomes among bacterial populations. Its role in mediating infectious disease has led to the elucidation of numerous autoinducers and their corresponding QS signaling pathways. Among them, the Lsr (LuxS-regulated) QS system is conserved in scores of bacteria, and its signal molecule, autoinducer-2 (AI-2), is synthesized as a product of 1-carbon metabolism. Lsr signal transduction processes, therefore, may help organize population scale activities in numerous bacterial consortia. Conceptions of how Lsr QS organizes population scale behaviors remain limited, however. Using mathematical simulations, we examined how desynchronized Lsr QS activation, arising from cell-to-cell population heterogeneity, could lead to bimodal Lsr signaling and fractional activation. This has been previously observed experimentally. Governing these processes are an asynchronous AI-2 uptake, where positive intracellular feedback in Lsr expression is combined with negative feedback between cells. The resulting activation patterns differ from that of the more widely studied LuxIR system, the topology of which consists of only positive feedback. To elucidate differences, both QS systems were simulated in 2D, where cell populations grow and signal each other via traditional growth and diffusion equations. Our results demonstrate that the LuxIR QS system produces an ‘outward wave’ of autoinduction, and the Lsr QS system yields dispersed autoinduction from spatially-localized secretion and uptake profiles. In both cases, our simulations mirror previously demonstrated experimental results. As a whole, these models inform QS observations and synthetic biology designs. PMID:27071007

  10. Estimation of streamflow, base flow, and nitrate-nitrogen loads in Iowa using multiple linear regression models

    USGS Publications Warehouse

    Schilling, K.E.; Wolter, C.F.

    2005-01-01

    Nineteen variables, including precipitation, soils and geology, land use, and basin morphologic characteristics, were evaluated to develop Iowa regression models to predict total streamflow (Q), base flow (Qb), storm flow (Qs) and base flow percentage (%Qb) in gauged and ungauged watersheds in the state. Discharge records from a set of 33 watersheds across the state for the 1980 to 2000 period were separated into Qb and Qs. Multiple linear regression found that 75.5 percent of long term average Q was explained by rainfall, sand content, and row crop percentage variables, whereas 88.5 percent of Qb was explained by these three variables plus permeability and floodplain area variables. Qs was explained by average rainfall and %Qb was a function of row crop percentage, permeability, and basin slope variables. Regional regression models developed for long term average Q and Qb were adapted to annual rainfall and showed good correlation between measured and predicted values. Combining the regression model for Q with an estimate of mean annual nitrate concentration, a map of potential nitrate loads in the state was produced. Results from this study have important implications for understanding geomorphic and land use controls on streamflow and base flow in Iowa watersheds and similar agriculture dominated watersheds in the glaciated Midwest. (JAWRA) (Copyright ?? 2005).

  11. Developing a cell-based sensor for the detection of Autoinducer-2

    NASA Astrophysics Data System (ADS)

    Servinsky, Matthew D.; Germane, Katherine; Gerlach, Elliot S.; Tsao, Chen-Yu; Byrd, Christopher M.; Sund, Christian J.; Bentley, William E.

    2013-05-01

    Bacteria use an intricate set of communication systems for sensing and interpreting environmental cues that coordinate population-based behavior. Quorum sensing is one of these systems, and it involves the production, release, and detection of small chemical signaling molecules. Recent research has revealed the role of quorum sensing molecules in the control of microbial activities such as biofilm formation. In this presentation we outline the development of a recombinant E. coli cell-based sensor for detection of the quorum sensing molecule Autoinducer-2 (AI-2), as well as engineering strategies to remove sugar and anoxic inhibition of the strain.

  12. Quorum Sensing in Marine Microbial Environments

    NASA Astrophysics Data System (ADS)

    Hmelo, Laura R.

    2017-01-01

    Quorum sensing (QS) is a form of chemical communication used by certain bacteria that regulates a wide range of biogeochemically important bacterial behaviors. Although QS was first observed in a marine bacterium nearly four decades ago, only in the past decade has there been a rise in interest in the role that QS plays in the ocean. It has become clear that QS, regulated by signals such as acylated homoserine lactones (AHLs) or furanosyl-borate diesters [autoinducer-2 (AI-2) molecules], is involved in important processes within the marine carbon cycle, in the health of coral reef ecosystems, and in trophic interactions between a range of eukaryotes and their bacterial associates. The most well-studied QS systems in the ocean occur in surface-attached (biofilm) communities and rely on AHL signaling. AHL-QS is highly sensitive to the chemical and biological makeup of the environment and may respond to anthropogenic change, including ocean acidification and rising sea surface temperatures.

  13. X-Ray Diffraction Analysis of the Sintered Y-TZP-AI2O3 Ceramics

    NASA Astrophysics Data System (ADS)

    Savchenko, Nickolai; Sablina, Tatiana; Sevostyanova, Irina; Pshenichnyy, Artem; Buyakova, Svetlana; Kulkov, Sergei

    2016-07-01

    The paper discusses the wear resistance, friction coefficient, and structure of friction surfaces of fine-grained (0.2 µm) Y-TZP-Al2O3 composite rubbed against a steel disk counterface at a pressure of 5 MPa in a range of sliding speeds from 1 to 20 m/sec. It is shown that, starting at 2 m/sec, the fricti on surface is subdivided by a crack network into separate regions within which local spalling occurs at the maximum wear rate and a sliding speed of 5 m/sec. X-ray diffraction reveals inversion (with respect to the initial state) of the peak intensities of the tetragonal phase with random crystalline grain orientation. The degree of this inversion increases with sliding speed. These results are discussed in terms of the effects exerted by the reorientation of martensite-free deformation twins in the tetragonal phase and the formation of a quasi-liquid film on the wear resistance of fine-grained Y-TZP-Al2O3.

  14. Structures Formation on the Y-TZP-AI2O3 Ceramic Composites Surface

    NASA Astrophysics Data System (ADS)

    Kulkov, Sergei; Sevostyanova, Irina; Sablina, Tatiana; Buyakova, Svetlana; Pshenichnyy, Artem; Savchenko, Nickolai

    2016-07-01

    The paper discusses the structure of Y-TZP-Al2O3 ceramics produced from nanopowders and friction surface, wear resistance, friction coefficient of Y-TZP-AEO3 composites rubbed against a steel disk counterface at a pressure of 5 MPa in a range of sliding speeds from 0.2 to 47 m/s. Analysis by X-ray diffraction, scanning electron microscopy showed that the high wear resistance of Y-TZP-Al2O3 composites at high sliding speeds is due to high-temperature phase transitions and protective film formation on the friction surface.

  15. AIS-2 radiometry and a comparison of methods for the recovery of ground reflectance

    NASA Technical Reports Server (NTRS)

    Conel, James E.; Green, Robert O.; Vane, Gregg; Bruegge, Carol J.; Alley, Ronald E.; Curtiss, Brian J.

    1987-01-01

    A field experiment and its results involving Airborne Imaging Spectrometer-2 data are described. The radiometry and spectral calibration of the instrument are critically examined in light of laboratory and field measurements. Three methods of compensating for the atmosphere in the search for ground reflectance are compared. It was found that laboratory determined responsitivities are 30 to 50 percent less than expected for conditions of the flight for both short and long wavelength observations. The combined system atmosphere surface signal to noise ratio, as indexed by the mean response divided by the standard deviation for selected areas, lies between 40 and 110, depending upon how scene averages are taken, and is 30 percent less for flight conditions than for laboratory. Atmospheric and surface variations may contribute to this difference. It is not possible to isolate instrument performance from the present data. As for methods of data reduction, the so-called scene average or log-residual method fails to recover any feature present in the surface reflectance, probably because of the extreme homogeneity of the scene.

  16. Numerical simulation of armor capability of AI2O3 and SiC armor tiles

    NASA Astrophysics Data System (ADS)

    Rashid, T.; Aleem, M. A.; Akbar, S.; Rauf, A.; Shuaib, M.

    2016-08-01

    Alumina and Silicon Carbide armor plates have been tested numerically against 7.62x51 (mm x mm) armor piercing (AP) projectiles. A 2-D problem with axial symmetry has been designedand the simulations were carried out using commercial software ANSYS AUTODYN. Experiments were modeled for Alumina (99.5%), Alumina (99.7%) and SiC with a range of tile thicknesses (5, 10, 15 and 20 mm). The projectile was chosen as 7.62 x 51AP bullet (initial velocity 810 m/sec)with two different core materials Steel 4340 and WC, however, casing material was copper for both cores. SiC showed better defense against AP bullet as compared to Al2O3. The residual velocity and momentum of the bullet were found to decrease with increasing tile thickness. SiC tiles with thickness 15mm and 20 mm successfully sustained penetration against steel 4340 and WC core bullets, respectively. However none of the Alumina targets succeeded in stopping the bullet.

  17. DNA microarray analysis reveals crosstalk of Salmonella enterica serovar Typhimurium with AI-2 of Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quorum sensing, or cell-to-cell communication, is made possible by the production and sensing of small, extracellular chemical signals called autoinducers (AI). These autoinducers accumulate as the population density increases, and thereby help bacteria to regulate their behavior by promoting or rep...

  18. Paradox in AI - AI 2.0: The Way to Machine Consciousness

    NASA Astrophysics Data System (ADS)

    Palensky, Peter; Bruckner, Dietmar; Tmej, Anna; Deutsch, Tobias

    Artificial Intelligence, the big promise of the last millennium, has apparently made its way into our daily lives. Cell phones with speech control, evolutionary computing in data mining or power grids, optimized via neural network, show its applicability in industrial environments. The original expectation of true intelligence and thinking machines lies still ahead of us. Researchers are, however, optimistic as never before. This paper tries to compare the views, challenges and approaches of several disciplines: engineering, psychology, neuroscience, philosophy. It gives a short introduction to Psychoanalysis, discusses the term consciousness, social implications of intelligent machines, related theories, and expectations and shall serve as a starting point for first attempts of combining these diverse thoughts.

  19. Phenotypic and Genotypic Characterisation of Burkholderia cenocepacia J2315 Mutants Affected in Homoserine Lactone and Diffusible Signal Factor-Based Quorum Sensing Systems Suggests Interplay between Both Types of Systems

    PubMed Central

    Udine, Claudia; Brackman, Gilles; Bazzini, Silvia; Buroni, Silvia; Van Acker, Heleen; Pasca, Maria Rosalia; Riccardi, Giovanna; Coenye, Tom

    2013-01-01

    Many putative virulence factors of Burkholderia cenocepacia are controlled by various quorum sensing (QS) circuits. These QS systems either use N-acyl homoserine lactones (AHL) or cis-2-dodecenoic acid (“Burkholderia diffusible signal factor”, BDSF) as signalling molecules. Previous work suggested that there is little cross-talk between both types of systems. We constructed mutants in B. cenocepacia strain J2315, in which genes encoding CepI (BCAM1870), CciI (BCAM0239a) and the BDSF synthase (BCAM0581) were inactivated, and also constructed double (ΔcepIΔBCAM0581, ΔcciIΔBCAM0581 and ΔcepIΔcciI) mutants and a triple (ΔcepIΔcciIΔBCAM0581) mutant. Subsequently we investigated phenotypic properties (antibiotic susceptibility, biofilm formation, production of AHL and BDSF, protease activity and virulence in Caenorhabditis elegans) and measured gene expression in these mutants, and this in the presence and absence of added BDSF, AHL or both. The triple mutant was significantly more affected in biofilm formation, antimicrobial susceptibility, virulence in C. elegans, and protease production than either the single or double mutants. The ΔBCAM0581 mutant and the ΔcepIΔBCAM0581 and ΔcciIΔBCAM0581 double mutants produced significantly less AHL compared to the WT strain and the ΔcepI and ΔcciI single mutant, respectively. The expression of cepI and cciI in ΔBCAM0581, was approximately 3-fold and 7-fold (p<0.05) lower than in the WT, respectively. The observed differences in AHL production, expression of cepI and cciI and QS-controlled phenotypes in the ΔBCAM0581 mutant could (at least partially) be restored by addition of BDSF. Our data suggest that, in B. cenocepacia J2315, AHL and BDSF-based QS systems co-regulate the same set of genes, regulate different sets of genes that are involved in the same phenotypes and/or that the BDSF system controls the AHL-based QS system. As the expression of the gene encoding the C6-HSL synthase CciI (and to a lesser

  20. Construction of a cell-based sensor for the detection of autoinducer-2

    NASA Astrophysics Data System (ADS)

    Servinsky, Matthew D.; Allen, Patrick C.; Tsao, Chen-Yu; Byrd, Christopher M.; Sund, Christian J.; Bentley, William E.

    2012-05-01

    Microbially Induced Corrosion (MIC) occurs at metal surfaces and is associated with microorganisms and their metabolic activities. These microbes can coexist as biofilms, growing as synergistic communities (consortia) that are able to affect electrochemical processes, both cathodic and anodic, often through co-operative metabolism. Recent research has revealed the role of "quorum sensing" molecules in control of microbial activities such as biofilm formation. In this paper, we propose the detection of quorum sensing molecules as a means of detecting bacterial contamination prior to the onset on biofilm formation. Further we outline the development of an E. coli cell based sensor for detection of the quorum sensing molecule Autoinducer-2 (AI-2).

  1. 50 CFR 679.40 - Sablefish and halibut QS.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., landing, or reporting. State catch reports are Alaska, Washington, Oregon, or California fish tickets... catch history, vessel ownership or lease data, and other information supplied by an applicant will be...) Unverified data. Catch history, vessel ownership, or lease data that cannot be verified by the...

  2. 50 CFR 679.40 - Sablefish and halibut QS.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., landing, or reporting. State catch reports are Alaska, Washington, Oregon, or California fish tickets... catch history, vessel ownership or lease data, and other information supplied by an applicant will be...) Unverified data. Catch history, vessel ownership, or lease data that cannot be verified by the...

  3. 50 CFR 679.40 - Sablefish and halibut QS.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., landing, or reporting. State catch reports are Alaska, Washington, Oregon, or California fish tickets... catch history, vessel ownership or lease data, and other information supplied by an applicant will be...) Unverified data. Catch history, vessel ownership, or lease data that cannot be verified by the...

  4. 50 CFR 679.40 - Sablefish and halibut QS.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., landing, or reporting. State catch reports are Alaska, Washington, Oregon, or California fish tickets... catch history, vessel ownership or lease data, and other information supplied by an applicant will be...) Unverified data. Catch history, vessel ownership, or lease data that cannot be verified by the...

  5. 50 CFR 679.40 - Sablefish and halibut QS.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., landing, or reporting. State catch reports are Alaska, Washington, Oregon, or California fish tickets... catch history, vessel ownership or lease data, and other information supplied by an applicant will be...) Unverified data. Catch history, vessel ownership, or lease data that cannot be verified by the...

  6. 50 CFR 679.80 - Initial allocation of rockfish QS.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Rockfish entry level fishery—longline gear vessels. Fishing by vessels participating in the longline gear portion of the rockfish entry level fishery is authorized from 0001 hours, A.l.t., January 1 through 1200 hours, A.l.t., November 15. (ii) Rockfish entry level fishery—trawl vessels. Fishing by...

  7. 50 CFR 679.80 - Initial allocation of rockfish QS.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Rockfish entry level fishery—longline gear vessels. Fishing by vessels participating in the longline gear portion of the rockfish entry level fishery is authorized from 0001 hours, A.l.t., January 1 through 1200 hours, A.l.t., November 15. (ii) Rockfish entry level fishery—trawl vessels. Fishing by...

  8. Inhibition of quorum sensing, biofilm, and spoilage potential in Shewanella baltica by green tea polyphenols.

    PubMed

    Zhu, Junli; Huang, Xuzheng; Zhang, Fang; Feng, Lifang; Li, Jianrong

    2015-12-01

    We investigated the quorum sensing (QS) system of Shewanella baltica and the anti-QS related activities of green tea polyphenols (TP) against spoilage bacteria in refrigerated large yellow croaker. Autoinducer-2 (AI-2) and the diketopiperazines (DKPs) cyclo-(L-Pro-L-Leu) and cyclo-(L-Pro-L-Phe) were detected in the culture extract of S. baltica XH2, however, no N-acylhomoserine lactones (AHLs) activity was observed. Green TP at sub-inhibitory concentrations interfered with AI-2 and DKPs activities of S. baltica without inhibiting cell growth and promoted degradation of AI-2. The green TP treatment inhibited biofilm development, exopolysaccharide production and swimming motility of S. baltica in a concentration- dependent manner. In addition, green TP decreased extracellular protease activities and trimethylamine production in S. baltica. A transcriptional analysis showed that green TP repressed the luxS and torA genes in S. baltica, which agreed with the observed reductions in QS activity and the spoilage phenotype. Epigallocatechin gallate (EGCG)-enriched in green TP significantly inhibited AI-2 activity of S. baltica. These findings strongly suggest that green TP could be developed as a new QS inhibitor for seafood preservation to enhance shelf life.

  9. Timing of left heart base descent in dogs with dilated cardiomyopathy and normal dogs.

    PubMed

    Simpson, Kerry E; Devine, Bryan C; Woolley, Richard; Corcoran, Brendan M; French, Anne T

    2008-01-01

    The identification and assessment of myocardial failure in canine idiopathic dilated cardiomyopathy (DCM) is achieved using a variety of two-dimensional and Doppler echocardiographic techniques. More recently, the availability of tissue Doppler imaging (TDI) has raised the potential for development of new ways of more accurately identifying a disease phenotype. Nevertheless, TDI has not been universally adapted to veterinary clinical cardiology primarily because of the lack of information on its utility in diagnosis. We assessed the application of timing of left heart base descent using TDI in the identification of differences between DCM and normal dogs. The times from the onset of the QRS complex on a simultaneously recorded electrocardiograph to the onset (Q--S'), peak (Q--peak S'), and end (Q--end S') of the systolic velocity peak were measured in the interventricular septum (IVS) and the left ventricular free wall. The duration of S' was also calculated. The Q--S' (FW), Q--end S' (FW), and duration S' (FW) were correlated with ejection fraction in the diseased group (P < 0.05). In addition, Q--S', Q--peak S', Q--end S', and the peak S' velocity were prolonged in the diseased dogs at both the free wall and in the IVS (P < 0.01). The duration of S' was unaffected by disease status. These findings provide insight into the electromechanical uncoupling that occurs in canine DCM and identifies new TDI parameters that can be added to the range of Doppler and echocardiographic parameters used for detecting myocardial failure in the dog.

  10. Beneficial effects of bacteria-plant communication based on quorum sensing molecules of the N-acyl homoserine lactone group.

    PubMed

    Schikora, Adam; Schenk, Sebastian T; Hartmann, Anton

    2016-04-01

    Bacterial quorum sensing (QS) mechanisms play a crucial role in the proper performance and ecological fitness of bacterial populations. Many key physiological processes are regulated in a QS-dependent manner by auto-inducers, like the N-acyl homoserine lactones (AHLs) in numerous Gram-negative bacteria. In addition, also the interaction between bacteria and eukaryotic hosts can be regulated by AHLs. Those mechanisms gained much attention, because of the positive effects of different AHL molecules on plants. This positive impact ranges from growth promotion to induced resistance and is quite contrasting to the rather negative effects observed in the interactions between bacterial AHL molecules and animals. Only very recently, we began to understand the molecular mechanisms underpinning plant responses to AHL molecules. In this review, we gathered the latest information in this research field. The first part gives an overview of the bacterial aspects of quorum sensing. Later we focus on the impact of AHLs on plant growth and AHL-priming, as one of the most understood phenomena in respect to the inter-kingdom interactions based on AHL-quorum sensing molecules. Finally, we discuss the potential benefits of the understanding of bacteria-plant interaction for the future agricultural applications.

  11. Three-Dimensional Numerical Simulations of Biofilm Dynamics with Quorum Sensing in a Flow Cell.

    PubMed

    Zhao, Jia; Wang, Qi

    2017-03-13

    We develop a multiphasic hydrodynamic theory for biofilms taking into account interactions among various bacterial phenotypes, extracellular polymeric substance (EPS), quorum sensing (QS) molecules, solvent, and antibiotics. In the model, bacteria are classified into down-regulated QS, up-regulated QS, and non-QS cells based on their QS ability. The model is first benchmarked against an experiment yielding an excellent fit to experimental measurements on the concentration of QS molecules and the cell density during biofilm development. It is then applied to study development of heterogeneous structures in biofilms due to interactions of QS regulation, hydrodynamics, and antimicrobial treatment. Our 3D numerical simulations have confirmed that (i). QS is beneficial for biofilm development in a long run by building a robust EPS population to protect the biofilm; (ii). biofilms located upstream can induce QS downstream when the colonies are close enough spatially; (iii). QS induction may not be fully operational and can even be compromised in strong laminar flows; (v). the hydrodynamic stress alters the biofilm morphology. Through further numerical investigations, our model suggests that (i). QS-regulated EPS production contributes to the structural formation of heterogeneous biofilms; (ii) QS down-regulated cells tend to grow at the surface of the biofilm while QS up-regulated ones tend to grow in the bulk; (iii) when nutrient supply is sufficient, QS induction might be more effective upstream than downstream; (iv) QS may be of little benefit in a short timescale in term of fighting against invading strain/species; (v) the material properties of biomass (bacteria and EPS) have strong impact on the dilution of QS molecules under strong shear flow. In addition, with this modeling framework, hydrodynamic details and rheological quantities associated with biofilm formation under QS regulation can be resolved.

  12. Real-time water and wastewater quality monitoring using LED-based fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Bridgeman, John; Zakharova, Yulia

    2016-04-01

    In recent years there have been a number of attempts to design and introduce into water management tools that are capable of measuring organic and microbial matter in real time and in situ. This is important, as the delivery of safe water to customers, and the discharge of good quality effluent to rivers are primary concerns to water undertakers. A novel, LED-based portable fluorimeter 'Duo Fluor' has been designed and constructed at the University of Birmingham to monitor the quality of (waste)water continuously and in real time, and its performance has been assessed in a range of environments. To be of use across a range of environments, special attention must be paid to two crucially important characteristics of such instruments, i.e. their sensitivity and robustness. Thus, the objectives of this study were: 1. To compare the performance (in terms of their sensitivity and robustness) of the Duo Fluor and two other commercial fluorescence devices in laboratory conditions. 2. To assess the performance of the Duo Fluor in situ, in real time at a 450,000PE WwTW. Initially, the impact of quinine sulphate (QS), a highly fluorescent alkaloid with high quantum fluorescence yield, on peak T fluorescence in environmental waters was examined for the Duo Fluor and two commercially available, chamber-based fluorimeters, (F1) and (F2). The instruments' responses to three scenarios were assessed: 1. Deionised water (DW) spiked with QS (from 0.05 to 0.4 mg/L); 2. Environmental water (pond water, PW) spiked with QS (from 0.05 to 0.4 mg/L); 3. Different water samples from various environmental source. The results show that the facility to amend gain settings and the suitable choice of gain are crucial to obtaining reliable data on both peaks T and C in a wide range of water types. The Duo Fluor offers both of these advantages whilst commercially available instruments currently do not. The Duo Fluor was subsequently fixed at the final effluent (FE) discharge point of a WwTW and FE

  13. 2 μm and mid-IR fiber-laser-based sources for OCM

    NASA Astrophysics Data System (ADS)

    Kieleck, C.; Berrou, A.; Kneis, C.; Donelan, B.; Eichhorn, M.

    2014-10-01

    This paper describes new laser sources and non linear conversion setups for 2 μm and mid-IR generation based on fiber technologies developed at ISL. Especially for jamming heat-seeking missiles, these novel designs allow to propose future compact, efficient and integrable laser systems. The specialty of the ISL technology lies in the use of single 2 μm fiber laser oscillators, which deliver the full output peak power to pump optical parametric oscillators or nonlinear fibers. No multi-stage amplifiers at 2 μm or 1.55 μm are necessary to efficiently pump non linear converters to obtained useful energies in the mid-infrared spectral range. This technology leads to efficient, simple and promising setups to be implemented in flying platforms. The best results achieved in continuous-wave (CW), Q-switched (QS) and mode-locked (ML) regimes with fiber lasers based on Tm3+-doped and Tm3+,Ho3+-codoped fibers are presented. Up to 70 W of average power was achieved around 2 μm with a Tm3+-doped fiber in CW regime. In ML regimes, at a repetition rate of 66 MHz, 50 W of average power was reached. In QS regime, up to 32 W of average power was generated around 2 μm with a polarization maintaining Tm3+-doped fiber at a repetition rate of 40 kHz. With a Tm3+,Ho3+-codoped fiber, up to 25 W of average power was obtained around 2070 nm in Q-switched regime. For example at 50 kHz, the pulse duration was around 50 ns at the maximum output power. The M2 was estimated to be less than 1.2. The emission from QS fiber lasers was used to directly pump OP-GaAs and ZGP OPOs. For example, in band II, up to 6.5 W of averaged power was recently obtained from a ZGP OPO pumped by a Tm3+-doped fiber laser. At 40 kHz repetition rate, the pulse duration was around 65 ns at the maximum output power. For 3 W of averaged output power, the M2 of the signal beam was estimated to be less than 2.1 and less than 2.4 for the idler beam. Using a mode-locked Tm3+-doped fiber laser to pump a ZBLAN fiber at an

  14. Peptide-based communication system enables Escherichia coli to Bacillus megaterium interspecies signaling.

    PubMed

    Marchand, Nicholas; Collins, Cynthia H

    2013-11-01

    The use of mixtures of microorganisms, or microbial consortia, has the potential to improve the productivity and efficiency of increasingly complex bioprocesses. However, the use of microbial consortia has been limited by our ability to control and coordinate the behaviors of microorganisms in synthetic communities. Synthetic biologists have previously engineered cell-cell communication systems that employ machinery from bacterial quorum-sensing (QS) networks to enable population-level control of gene expression. However, additional communication systems, such as those that enable communication between different species of bacteria, are needed to enable the use of diverse species in microbial consortia for bioprocessing. Here, we use the agr QS system from Staphylococcus aureus to generate an orthogonal synthetic communication system between Gram-negative Escherichia coli and Gram-positive Bacillus megaterium that is based on the production and recognition of autoinducing peptides (AIPs). We describe the construction and characterization of two types of B. megaterium "receiver" cells, capable of AIP-dependent gene expression in response to AIPs that differ by a single amino acid. Further, we observed interspecies communication when these receiver cells were co-cultured with AIP-producing E. coli. We show that the two AIP-based systems exhibit differences in sensitivity and specificity that may be advantageous in tuning communication-dependent networks in synthetic consortia. These peptide-based communication systems will enable the coordination of gene expression, metabolic pathways and growth between diverse microbial species, and represent a key step towards the use of microbial consortia in bioprocessing and biomanufacturing.

  15. Inhibitory effects of broccoli extract on Escherichia coli O157:H7 quorum sensing and in vivo virulence.

    PubMed

    Lee, Kang-Mu; Lim, Jeesun; Nam, Sunyoung; Yoon, Mi Young; Kwon, Yong-Kuk; Jung, Byeong Yeal; Park, Yongjin; Park, Sungsu; Yoon, Sang Sun

    2011-08-01

    Broccoli extract (BE) has numerous beneficial effects on human health including anticancer activity. Quorum sensing (QS), mediated by self-produced autoinducer (AI) molecules, is a key process for the production of virulence determinants in pathogenic bacteria. BE suppressed AI-2 synthesis and AI-2-mediated bacterial motility in a dose-dependent manner in Escherichia coli O157:H7. In addition, expression of the ler gene that regulates AI-3 QS system was also diminished in response to treatment with BE. Furthermore, in an in vivo efficacy test using Caenorhabditis elegans as a host organism, C. elegans fed on E. coli O157:H7 in the presence of BE survived longer than those fed solely on the pathogenic bacteria. Quantitative real-time PCR analysis indicated that quercetin was the most active among the tested broccoli-derived compounds in downregulating virulence gene expression, while treatment with myricetin significantly suppressed the expression of the eae gene involved in type III secretion system. These data suggest that BE and its flavonoid constituents can inhibit expression of QS-associated genes, thereby downregulating the virulence attributes of E. coli O157:H7 both in vitro and in vivo. This study clearly elucidates BE's QS-inhibitory activity and suggests that BE has the potential to be developed as an anti-infective agent.

  16. Autoinducer-2-based chemical communication in bacteria: complexities of interspecies signaling.

    PubMed

    Federle, Michael J

    2009-01-01

    Cell-cell communication in bacteria, called quorum sensing, relies on production, release, and detection of signaling molecules, termed autoinducers. Communication enables populations of cells to synchronize gene expression and therefore behave as a group in a manner akin to cells in multicellular organisms. Most quorum-sensing systems allow communication within an individual species of bacteria. However, one autoinducer, called AI-2, is produced and recognized by many different bacterial species, indicating that some bacteria communicate across species boundaries. Current studies are aimed at discovering the role that AI-2 plays in gene regulation. Differential gene expression in response to AI-2 may cause bacterial behavioral changes, such as biofilm formation or transition to a pathogenic state. Interestingly, multiple mechanisms to detect AI-2 exist. These differences likely reflect variations in the role that AI-2 plays for different bacteria. Additionally, structural analyses of the AI-2 receptor in V. harveyi have provided insight into bacterial trans-membrane signal transduction. A further understanding of bacterial quorum-sensing processes may facilitate development of new technologies aimed at interfering with bacterial communication and virulence.

  17. Quantifying the tracking capability of space-based AIS systems

    NASA Astrophysics Data System (ADS)

    Skauen, Andreas Nordmo

    2016-01-01

    The Norwegian Defence Research Establishment (FFI) has operated three Automatic Identification System (AIS) receivers in space. Two are on dedicated nano-satellites, AISSat-1 and AISSat-2. The third, the NORAIS Receiver, was installed on the International Space Station. A general method for calculating the upper bound on the tracking capability of a space-based AIS system has been developed and the results from the algorithm applied to AISSat-1 and the NORAIS Receiver individually. In addition, a constellation of AISSat-1 and AISSat-2 is presented. The tracking capability is defined as the probability of re-detecting ships as they move around the globe and is explained to represent and upper bound on a space-based AIS system performance. AISSat-1 and AISSat-2 operates on the nominal AIS1 and AIS2 channels, while the NORAIS Receiver data used are from operations on the dedicated space AIS channels, AIS3 and AIS4. The improved tracking capability of operations on the space AIS channels is presented.

  18. Resilience of bacterial quorum sensing against fluid flow

    NASA Astrophysics Data System (ADS)

    Emge, Philippe; Moeller, Jens; Jang, Hongchul; Rusconi, Roberto; Yawata, Yutaka; Stocker, Roman; Vogel, Viola

    2016-09-01

    Quorum sensing (QS) is a population-density dependent chemical process that enables bacteria to communicate based on the production, secretion and sensing of small inducer molecules. While recombinant constructs have been widely used to decipher the molecular details of QS, how those findings translate to natural QS systems has remained an open question. Here, we compare the activation of natural and synthetic Pseudomonas aeruginosa LasI/R QS systems in bacteria exposed to quiescent conditions and controlled flows. Quantification of QS-dependent GFP expression in suspended cultures and in surface-attached microcolonies revealed that QS onset in both systems was similar under quiescent conditions but markedly differed under flow. Moderate flow (Pe > 25) was sufficient to suppress LasI/R QS recombinantly expressed in Escherichia coli, whereas only high flow (Pe > 102) suppressed QS in wild-type P. aeruginosa. We suggest that this difference stems from the differential production of extracellular matrix and that the matrix confers resilience against moderate flow to QS in wild-type organisms. These results suggest that the expression of a biofilm matrix extends the environmental conditions under which QS-based cell-cell communication is effective and that findings from synthetic QS circuits cannot be directly translated to natural systems.

  19. Resilience of bacterial quorum sensing against fluid flow

    PubMed Central

    Emge, Philippe; Moeller, Jens; Jang, Hongchul; Rusconi, Roberto; Yawata, Yutaka; Stocker, Roman; Vogel, Viola

    2016-01-01

    Quorum sensing (QS) is a population-density dependent chemical process that enables bacteria to communicate based on the production, secretion and sensing of small inducer molecules. While recombinant constructs have been widely used to decipher the molecular details of QS, how those findings translate to natural QS systems has remained an open question. Here, we compare the activation of natural and synthetic Pseudomonas aeruginosa LasI/R QS systems in bacteria exposed to quiescent conditions and controlled flows. Quantification of QS-dependent GFP expression in suspended cultures and in surface-attached microcolonies revealed that QS onset in both systems was similar under quiescent conditions but markedly differed under flow. Moderate flow (Pe > 25) was sufficient to suppress LasI/R QS recombinantly expressed in Escherichia coli, whereas only high flow (Pe > 102) suppressed QS in wild-type P. aeruginosa. We suggest that this difference stems from the differential production of extracellular matrix and that the matrix confers resilience against moderate flow to QS in wild-type organisms. These results suggest that the expression of a biofilm matrix extends the environmental conditions under which QS-based cell-cell communication is effective and that findings from synthetic QS circuits cannot be directly translated to natural systems. PMID:27650454

  20. Quorum sensing signals affect spoilage of refrigerated large yellow croaker (Pseudosciaena crocea) by Shewanella baltica.

    PubMed

    Zhu, Junli; Zhao, Aifei; Feng, Lifang; Gao, Haichun

    2016-01-18

    In this work we investigated the specific spoilage organism (SSO) of large yellow croaker (Pseudosciaena crocea) stored at 4°C and role of quorum sensing (QS) system of SSO isolated from the spoiled fish. According to microbial count and 16S rRNA gene of the isolated pure strains, Shewanella, mainly Shewanella baltica and Shewanella putrefaciens, was predominant genera at the end of shelf-life of P. crocea. Among Shewanella isolates, S.baltica02 was demonstrated as SSO in spoilage potential characteristics by inoculation into sterile fish juice using sensory and chemical analyses. Autoinducer 2 and two cyclic dipeptides (DKPs) including cyclo-(l-Pro-l-Leu) and cyclo-(l-Pro-l-Phe), no any AHLs, were detected in cell-free S. baltica culture. Interestingly, S.baltica02 had the highest QS activity among three spoilers of S. baltica. The production of biofilm, trimethylamines (TMA) and putrescine in these spoilers significantly increased in the presence of cyclo-(l-Pro-l-Leu), rather than cyclo-(l-Pro-l-Phe) and 4,5-dihydroxy-2,3-pentanedione (the AI-2 precursor, DPD). In accordance with the effect of signal molecules on the spoilage phenotype, exposure to exogenous cyclo-(l-Pro-l-Leu) was also showed to up-regulate the transcription levels of luxR, torA and ODC, and no effect of luxS indicated that S. baltica could sense cyclo-(l-Pro-l-Leu). In the fish homogenate, exogenous cyclo-(l-Pro-l-Leu) shortened lag phase durations and enhanced growth rates of the dominant bacteria, H2S producing bacteria, under refrigerated storage, while exogenous DPD retarded growth of competing bacteria, such as Enterobacteriaceae. Meanwhile, cyclo-(l-Pro-l-Leu) also promoted the accumulation of metabolites on the spoilage process of homogenate. S.baltica02 luxS mutant preliminarily proved that AI-2 might not play a signaling role in the spoilage. The present study suggested that the spoilage potential of S. baltica in P. crocea might be regulated by DKP-based quorum sensing.

  1. The new pLAI (lux regulon based auto-inducible) expression system for recombinant protein production in Escherichia coli

    PubMed Central

    2012-01-01

    Background After many years of intensive research, it is generally assumed that no universal expression system can exist for high-level production of a given recombinant protein. Among the different expression systems, the inducible systems are the most popular for their tight regulation. However, induction is in many cases less favorable due to the high cost and/or toxicity of inducers, incompatibilities with industrial scale-up or detrimental growth conditions. Expression systems using autoinduction (or self-induction) prove to be extremely versatile allowing growth and induction of recombinant proteins without the need to monitor cell density or add inducer. Unfortunately, almost all the actual auto inducible expression systems need endogenous or induced metabolic changes during the growth to trigger induction, both frequently linked to detrimental condition to cell growth. In this context, we use a simple modular approach for a cell density-based genetic regulation in order to assemble an autoinducible recombinant protein expression system in E. coli. Result The newly designed pLAI expression system places the expression of recombinant proteins in Escherichia coli under control of the regulatory genes of the lux regulon of Vibrio fischeri's Quorum Sensing (QS) system. The pLAI system allows a tight regulation of the recombinant gene allowing a negligible basal expression and expression only at high cell density. Sequence optimization of regulative genes of QS of V. fischeri for expression in E. coli upgraded the system to high level expression. Moreover, partition of regulative genes between the plasmid and the host genome and introduction of a molecular safety lock permitted tighter control of gene expression. Conclusion Coupling gene expression to cell density using cell-to-cell communication provides a promising approach for recombinant protein production. The system allows the control of expression of the target recombinant gene independently from external

  2. A joint application of optimal threshold based discrete cosine transform and ASCII encoding for ECG data compression with its inherent encryption.

    PubMed

    Pandey, Anukul; Singh, Butta; Saini, Barjinder Singh; Sood, Neetu

    2016-12-01

    In this paper, a joint use of the discrete cosine transform (DCT), and differential pulse code modulation (DPCM) based quantization is presented for predefined quality controlled electrocardiogram (ECG) data compression. The formulated approach exploits the energy compaction property in transformed domain. The DPCM quantization has been applied to zero-sequence grouped DCT coefficients that were optimally thresholded via Regula-Falsi method. The generated sequence is encoded using Huffman coding. This encoded series is further converted to a valid ASCII code using the standard codebook for transmission purpose. Such a coded series possesses inherent encryption capability. The proposed technique is validated on all 48 records of standard MIT-BIH database using different measures for compression and encryption. The acquisition time has been taken in accordance to that existed in literature for the fair comparison with contemporary state-of-art approaches. The chosen measures are (1) compression ratio (CR), (2) percent root mean square difference (PRD), (3) percent root mean square difference without base (PRD1), (4) percent root mean square difference normalized (PRDN), (5) root mean square (RMS) error, (6) signal to noise ratio (SNR), (7) quality score (QS), (8) entropy, (9) Entropy score (ES) and (10) correlation coefficient (r x,y ). Prominently the average values of CR, PRD and QS were equal to 18.03, 1.06, and 17.57 respectively. Similarly, the mean encryption metrics i.e. entropy, ES and r x,y were 7.9692, 0.9962 and 0.0113 respectively. The novelty in combining the approaches is well justified by the values of these metrics that are significantly higher than the comparison counterparts.

  3. 50 CFR 679.42 - Limitations on use of QS and IFQ.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... transferor (seller); (F) A written declaration from a licensed medical doctor, advanced nurse practitioner... include: (1) The identity of the licensed medical doctor, advanced nurse practitioner, or primary..., advanced nurse practitioner, or primary community health aide; (2) A concise description of the...

  4. 50 CFR 679.42 - Limitations on use of QS and IFQ.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... transferor (seller); (F) A written declaration from a licensed medical doctor, advanced nurse practitioner... include: (1) The identity of the licensed medical doctor, advanced nurse practitioner, or primary..., advanced nurse practitioner, or primary community health aide; (2) A concise description of the...

  5. Toxic chemical release inventory reporting: Questions and answers (Qs&As)

    SciTech Connect

    Not Available

    1994-03-01

    On September 22, 1992, the Secretary of Energy directed the Department to participate in the Environmental Protection Agency`s (EPA) 33/50 Pollution Prevention Program and to initiate Toxic Chemical Release Inventory (TRI) reporting, pursuant to Section 313 of the Emergency Planning and Community Right-to-Know Act (EPCRA), at Department of Energy (DOE) sites. The Office of Environmental Guidance, RCRA/CERCLA Division (EH-231) issued interim guidance on March 4, 1993, entitled ``Toxic Chemical Release Inventory and 33/50 Pollution Prevention Program`` that provided instructions on implementing the Secretarial directive. As stated in the interim guidance, all DOE sites not currently reporting under EPCRA Section 313, which meet the criteria for DOE TRI reporting, will initiate reporting of all TRI chemical releases and transfers for the 1993 calendar year with the annual report due to EPA, States and a courtesy copy to EH-20 by July 1, 1994. All other DOE sites which currently report under EPCRA Section 313 will also follow the criteria for DOE TRI reporting.

  6. 50 CFR 679.42 - Limitations on use of QS and IFQ.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... transferor (seller); (F) A written declaration from a licensed medical doctor, advanced nurse practitioner... include: (1) The identity of the licensed medical doctor, advanced nurse practitioner, or primary..., advanced nurse practitioner, or primary community health aide; (2) A concise description of the...

  7. 50 CFR 679.42 - Limitations on use of QS and IFQ.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... transferor (seller); (F) A written declaration from a licensed medical doctor, advanced nurse practitioner... include: (1) The identity of the licensed medical doctor, advanced nurse practitioner, or primary..., advanced nurse practitioner, or primary community health aide; (2) A concise description of the...

  8. 50 CFR 679.42 - Limitations on use of QS and IFQ.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... written declaration from a licensed medical doctor, advanced nurse practitioner, or primary community... the licensed medical doctor, advanced nurse practitioner, or primary community health aide including... and state, zip code), and whether the individual is a licensed medical doctor, advanced...

  9. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Initial Issuance of Crab PQS by Crab...

  10. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Initial Issuance of Crab PQS by Crab...

  11. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial Issuance of Crab PQS by Crab...

  12. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Initial Issuance of Crab PQS by Crab...

  13. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Initial Issuance of Crab PQS by Crab...

  14. 50 CFR 680.41 - Transfer of QS, PQS, IFQ and IPQ.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... limited to: (i) Lack of U.S. citizenship, where U.S. citizenship is required; (ii) Failure to meet minimum...) An individual who is a U.S. citizen with at least 150 days of sea time as part of a harvesting crew in any U.S. commercial fishery. (C) A corporation, partnership, or other entity with at least...

  15. 50 CFR 680.41 - Transfer of QS, PQS, IFQ and IPQ.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... limited to: (i) Lack of U.S. citizenship, where U.S. citizenship is required; (ii) Failure to meet minimum...) An individual who is a U.S. citizen with at least 150 days of sea time as part of a harvesting crew in any U.S. commercial fishery. (C) A corporation, partnership, or other entity with at least...

  16. 50 CFR 679.80 - Allocation and transfer of rockfish QS.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... level longline fishery. Fishing by vessels participating in the rockfish entry level longline fishery is... during the season dates for the entry level trawl fishery in 2007, 2008, or 2009 for a rockfish primary... entry level trawl fishery in 2007, 2008, or 2009; and, (C) For an applicant who holds an LLP...

  17. 50 CFR 679.80 - Allocation and transfer of rockfish QS.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... level longline fishery. Fishing by vessels participating in the rockfish entry level longline fishery is... during the season dates for the entry level trawl fishery in 2007, 2008, or 2009 for a rockfish primary... entry level trawl fishery in 2007, 2008, or 2009; and, (C) For an applicant who holds an LLP...

  18. 50 CFR 679.80 - Allocation and transfer of rockfish QS.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... level longline fishery. Fishing by vessels participating in the rockfish entry level longline fishery is... during the season dates for the entry level trawl fishery in 2007, 2008, or 2009 for a rockfish primary... entry level trawl fishery in 2007, 2008, or 2009; and, (C) For an applicant who holds an LLP...

  19. Autoinducer-2-like activity associated with foods and its interaction with food additives.

    PubMed

    Lu, Lingeng; Hume, Michael E; Pillai, Suresh D

    2004-07-01

    The autoinducer-2 (AI-2) molecule produced by bacteria as part of quorum sensing is considered to be a universal inducer signal in bacteria because it reportedly influences gene expression in a variety of both gram-negative and gram-positive bacteria. The objective of this study was to determine whether selected fresh produce and processed foods have AI-2-like activity and whether specific food additives can act as AI-2 mimics and result in AI-2-like activity. The luminescence-based response of the reporter strain Vibrio harveyi BB170 was used as the basis for determining AI-2 activity in the selected foods and food ingredients. Maximum AI-2 activity was seen on the frozen fish sample (203-fold, compared with the negative control) followed by tomato, cantaloupe, carrots, tofu, and milk samples. Interestingly, some samples were capable of inhibiting AI-2 activity. Turkey patties showed the highest inhibition (99.8% compared with the positive control) followed by chicken breast (97.5%), homemade cheeses (93.7%), beef steak (90.6%), and beef patties (84.4%). AI-2 activity was almost totally inhibited by sodium propionate, whereas sodium benzoate caused 93.3% inhibition, compared with 75% inhibition by sodium acetate. Sodium nitrate did not have any appreciable effect, even at 200 ppm. Understanding the relationships that exist between AI-2 activity on foods and the ecology of pathogens and food spoilage bacteria on foods could yield clues about factors controlling food spoilage and pathogen virulence.

  20. Using granular C0-AI2O3 spacer for optimization of functional parameters of the FeMn/Fe20Ni80 magnetoresistive films

    NASA Astrophysics Data System (ADS)

    Gorkovenko, A. N.; Lepalovskij, V. N.; Adanakova, O. A.; Vas'kovskiy, V. O.

    2016-03-01

    In this paper we studied the possibility of tailoring the functional properties of the multilayer magnetoresistive medium with unidirectional anisotropy and the anisotropic magnetoresistance effect (AMR). Objects of the research were composite Co-Al2O3 films and Ta/Fe20Ni80/Fe50Mn50/Fe20Ni80/Co-Al2O3/Fe20Ni80/Ta multilayers structures obtained by magnetron sputtering and selectively subjected vacuum annealing. Structure, magnetic and magnetoresistive properties of the films in the temperature range 77÷440 K were investigated.

  1. Application of the high-temperature x-ray diffraction method to the diffusion study in the MgO-AI2O3 system

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Karwan-Baczewska, J.; Du, S.; Seetharaman, S.

    1996-10-01

    A mathematical model has been developed to study the kinetics of formation of spinel (MgAl2O4) using the high-temperature X-ray diffraction method. Experiments have been carried out for the MgO-Al2O3 system on an X-ray diffractometer in the temperature range of 1373 to 1673 K. Equimolar mixtures of MgO and A12O3 powders have been employed as the starting samples. The interdiffusivity values calculated from the high-temperature X-ray diffraction data using the present model are in good agreement with those obtained by diffusion couple experiments. The activation energy for the interdiffusion process has been found to be 354.2 kJ/mol in the temperature range 1473 to 1873 K.

  2. Iron, lanthanum and manganese oxides loaded on gamma-AI2O3 for selective catalytic reduction of NO with NH3 at low temperature.

    PubMed

    Zhao, Weiwei; Li, Caiting; Lu, Pei; Wen, Qingbo; Zhao, Yapei; Zhang, Xing; Fan, Chunzhen; Tao, Shasha

    2013-01-01

    A series of Mn/Al2O3, La-Mn/Al2O3 and Fe-La-Mn/Al2O3 catalysts were prepared by an impregnation method and investigated for selective catalytic reduction of NO with NH3 at low temperature. The experimental results revealed that NO conversion over La-Mn/Al2O3 was obviously improved after La doping. Addition of Fe increased both NO conversion and the resistance to H2O and SO2. The catalyst Fe0.04La0.03Mn0.06/Al2O3 with a load mass of MnO2 = 6%, La2O3 = 3% and Fe2O3 = 4% exhibited relatively high catalytic activity and yielded 98% NO conversion at 260 degrees with a space velocity of 15,000 h(-1). Meanwhile, the catalytic activity was slightly decreased in the presence of H2O and SO2. Moreover, the catalysts were characterized by N2 adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The results showed that the doping of La enhanced the dispersion and oxidation states of Mn on the surface of Al2O3. On the surface of the Fe0.04La0.03Mn0.06/Al2O3 catalyst, La was highly dispersed and a mixed oxidation state of Mn existed, while iron ions were only in the Fe3+ state. The mechanism of selective catalytic reduction over these catalysts is also discussed. In this experiment, metal oxides loaded on the support were catalytic centres which served as electron transfer during NO reduction. The electron transfer between Mn3+ and Fe3+ might also exist and the mixture oxidation states of Mn on the surface of the Fe0.04La0.03Mn0.06/Al2O3 catalyst contributed to the SCR activity.

  3. The influences of LuxX in Escherichia coli biofilm formation and improving teacher quality through the Bio-Bus Program

    NASA Astrophysics Data System (ADS)

    Robbins, Chandan Morris

    The objectives of this work are: (1) to agarose-stabilize fragile biofilms for quantitative structure analysis; (2) to understand the influences of LuxS on biofilm formation; (3) to improve teacher quality by preparing Georgia's middle school science teachers to integrate inquiry-based, hands-on research modules in the classroom. Quantitative digital image analysis demonstrated the effectiveness of the agarose stabilization technique for generating reproducible measurements of three dimensional biofilm structure. The described method will also benefit researchers who transport their flow cell-cultivated biofilms to a core facility for imaging. AI-2-dependent and independent effects of LuxS on biofilm-related phenotypes were revealed, suggesting that LuxS is a versatile enzyme, possessing multiple functions in E. coli ecology that could assist E. coli in adapting to diverse conditions. Overall, the work presented in this dissertation supported the concept that QS, biofilm formation, and cell adhesion are largely related. Additionally, through this project, teachers enhanced content knowledge and confidence levels, mastered innovative teaching strategies and integrated inquiry-based, inter-disciplinary, hands-on activities in the classroom. As a result, student learning was enhanced, and Georgia's students are better equipped to become tomorrow's leaders. INDEX WORDS: Biofilm, Escherichia coli, Quorum sensing, LuxS, Autoinducer-2, Microbial ecology

  4. RpoS and quorum sensing control expression and polar localization of Vibrio cholerae chemotaxis cluster III proteins in vitro and in vivo.

    PubMed

    Ringgaard, Simon; Hubbard, Troy; Mandlik, Anjali; Davis, Brigid M; Waldor, Matthew K

    2015-08-01

    The diarrheal pathogen Vibrio cholerae contains three gene clusters that encode chemotaxis-related proteins, but only cluster II appears to be required for chemotaxis. Here, we present the first characterization of V. cholerae's 'cluster III' chemotaxis system. We found that cluster III proteins assemble into foci at bacterial poles, like those formed by cluster II proteins, but the two systems assemble independently and do not colocalize. Cluster III proteins are expressed in vitro during stationary phase and in conjunction with growth arrest linked to carbon starvation. This expression, as well as expression in vivo in suckling rabbits, is dependent upon RpoS. V. cholerae's CAI-1 quorum sensing (QS) system is also required for cluster III expression in stationary phase and modulates its expression in vivo, but is not required for cluster III expression in response to carbon starvation. Surprisingly, even though the CAI-1 and AI-2 QS systems are thought to feed into the same signaling pathway, the AI-2 system inhibited cluster III gene expression, revealing that the outputs of the two QS systems are not always the same. The distinctions between genetic determinants of cluster III expression in vitro and in vivo highlight the distinctive nature of the in vivo environment.

  5. Quorum sensing in group A Streptococcus

    PubMed Central

    Jimenez, Juan Cristobal; Federle, Michael J.

    2014-01-01

    Quorum sensing (QS) is a widespread phenomenon in the microbial world that has important implications in the coordination of population-wide responses in several bacterial pathogens. In Group A Streptococcus (GAS), many questions surrounding QS systems remain to be solved pertaining to their function and their contribution to the GAS lifestyle in the host. The QS systems of GAS described to date can be categorized into four groups: regulator gene of glucosyltransferase (Rgg), Sil, lantibiotic systems, and LuxS/AI-2. The Rgg family of proteins, a conserved group of transcription factors that modify their activity in response to signaling peptides, has been shown to regulate genes involved in virulence, biofilm formation and competence. The sil locus, whose expression is regulated by the activity of signaling peptides and a putative two-component system (TCS), has been implicated on regulating genes involved with invasive disease in GAS isolates. Lantibiotic regulatory systems are involved in the production of bacteriocins and their autoregulation, and some of these genes have been shown to target both bacterial organisms as well as processes of survival inside the infected host. Finally AI-2 (dihydroxy pentanedione, DPD), synthesized by the LuxS enzyme in several bacteria including GAS, has been proposed to be a universal bacterial communication molecule. In this review we discuss the mechanisms of these four systems, the putative functions of their targets, and pose critical questions for future studies. PMID:25309879

  6. [Study on method of maize hybrid purity identification based on hyperspectral image technology].

    PubMed

    Jia, Shi-Qiang; Liu, Zhe; Li, Shao-Ming; Li, Lin; Ma, Qin; Zhang, Xiao-Dong; Zhu, De-Hai; Yan, Yan-Lu; An, Dong

    2013-10-01

    The feasibility of employing hyperspectral image technology to identify maize hybrid purity was studied by analyzing the spectral information of maize hyperspectral image. The hyperspectral images of hybrid and female parent of maize variety NH101 in the range of 871-1 699 nm including 308 wavelengths were collected by hyperspectral imaging system. We extracted average spectral information of interested region on maize seed and built identification models of hybrid and female parent of maize variety NH101 based on processed spectral data. The influences of different sample laying modes (seed embryo facing the light source, seed embryo backward light source, and seed put in different locations on sample stage) and experimental environments on the performance of identification models were discussed. Spectral collected under different sample laying modes and experimental environments were used to test the robustness of identification models. The average correct acceptance rates and average correct rejection rates are more than 90%. The feature spectral bands (1 195-1 246 nm) with which the differences between hybrid and female parent are the largest were extracted by a wavelength selection method based on standard deviations, called Qs. The performance of identification models built based on spectral data in feature spectral bands reached the same level of models built based on spectral data in the full range of 925-1 597 nm. The results demonstrated the feasibility of using hyperspectral image technology as an objective and rapid method for the identification of maize hybrid purity.

  7. Mechanisms of quorum sensing and strategies for quorum sensing disruption in aquaculture pathogens.

    PubMed

    Zhao, J; Chen, M; Quan, C S; Fan, S D

    2015-09-01

    In many countries, infectious diseases are a considerable threat to aquaculture. The pathogenicity of micro-organisms that infect aquaculture systems is closely related to the release of virulence factors and the formation of biofilms, both of which are regulated by quorum sensing (QS). Thus, QS disruption is a potential strategy for preventing disease in aquaculture systems. QS inhibitors (QSIs) not only inhibit the expression of virulence-associated genes but also attenuate the virulence of aquaculture pathogens. In this review, we discuss QS systems in important aquaculture pathogens and focus on the relationship between QS mechanisms and bacterial virulence in aquaculture. We further elucidate QS disruption strategies for targeting aquaculture pathogens. Four main types of QSIs that target aquaculture pathogens are discussed based on their mechanisms of action.

  8. Quorum sensing triggers the stochastic escape of individual cells from Pseudomonas putida biofilms.

    PubMed

    Cárcamo-Oyarce, Gerardo; Lumjiaktase, Putthapoom; Kümmerli, Rolf; Eberl, Leo

    2015-01-16

    The term 'quorum sensing' (QS) is generally used to describe the phenomenon that bacteria release and perceive signal molecules to coordinate cooperative behaviour in response to their population size. QS-based communication has therefore been considered a social trait. Here we show that QS signals (N-acyl-homoserine lactones, AHLs) are stochastically produced in young biofilms of Pseudomonas putida and act mainly as self-regulatory signals rather than inducing neighbouring cells. We demonstrate that QS induces the expression of putisolvin biosurfactants that are not public goods, thereby triggering asocial motility of induced cells out of microcolonies. Phenotypic heterogeneity is most prominent in the early stages of biofilm development, whereas at later stages behaviour patterns across cells become more synchronized. Our findings broaden our perspective on QS by showing that AHLs can control the expression of asocial (self-directed) traits, and that heterogeneity in QS can serve as a mechanism to drive phenotypic heterogeneity in self-directed behaviour.

  9. Quantitative RT-PCR analysis of differentially expressed genes in Quercus suber in response to Phytophthora cinnamomi infection.

    PubMed

    Ebadzad, Ghazal; Cravador, Alfredo

    2014-01-01

    cDNA-AFLP methodology was used to gain insight into gene fragments differentially present in the mRNA profiles of Quercus suber roots infected with zoospores of Phytophthora cinnamomi at different post challenge time points. Fifty-three transcript-derived fragments (TDFs) were identified and sequenced. Six candidate genes were selected based on their expression patterns and homology to genes known to play a role in defence. They encode a cinnamyl alcohol dehydrogenase2 (QsCAD2), a protein disulphide isomerase (QsPDI), a CC-NBS-LRR resistance protein (QsRPc), a thaumatin-like protein (QsTLP), a chitinase (QsCHI) and a 1,3-β-glucanase (QsGlu). Evaluation of the expression of these genes by quantitative polymerase chain reaction (qPCR) revealed that transcript levels of QsRPc, QsCHI, QsCAD2 and QsPDI increased during the first 24 h post-inoculation, while those of thaumatin-like protein decreased. No differential expression was observed for 1,3-β-glucanase (QsGlu). Four candidate reference genes, polymerase II (QsRPII), eukaryotic translation initiation factor 5A (QsEIF-5A), β-tubulin (QsTUB) and a medium subunit family protein of clathrin adaptor complexes (QsCACs) were assessed to determine the most stable internal references for qRT-PCR normalization in the Phytophthora-Q. suber pathosystem in root tissues. Those found to be more stable, QsRPII and QsCACs, were used as internal reference in the present work. Knowledge on the Quercus defence mechanisms against biotic stress is scarce. This study provides an insight into the gene profiling of a few important genes of Q. suber in response to P. cinnamomi infection contributing to the knowledge of the molecular interactions involving Quercus and root pathogens that can be useful in the future to understand the mechanisms underlying oak resistance to soil-borne oomycetes.

  10. DNA Microarray-Based Identification of Genes Controlled by Autoinducer 2-Stimulated Quorum Sensing in Escherichia coli

    PubMed Central

    DeLisa, Matthew P.; Wu, Chi-Fang; Wang, Liang; Valdes, James J.; Bentley, William E.

    2001-01-01

    Bacterial cell-to-cell communication facilitates coordinated expression of specific genes in a growth rate-II and cell density-dependent manner, a process known as quorum sensing. While the discovery of a diffusible Escherichia coli signaling pheromone, termed autoinducer 2 (AI-2), has been made along with several quorum sensing genes, the overall number and coordination of genes controlled by quorum sensing through the AI-2 signal has not been studied systematically. We investigated global changes in mRNA abundance elicited by the AI-2 signaling molecule through the use of a luxS mutant that was unable to synthesize AI-2. Remarkably, 242 genes, comprising ca. 5.6% of the E. coli genome, exhibited significant transcriptional changes (either induction or repression) in response to a 300-fold AI-2 signaling differential, with many of the identified genes displaying high induction levels (more than fivefold). Significant induction of ygeV, a putative ς54-dependent transcriptional activator, and yhbH, a ς54 modulating protein, suggests ς54 may be involved in E. coli quorum sensing. PMID:11514505

  11. Interaction between Streptococcus spp. and Veillonella tobetsuensis in the Early Stages of Oral Biofilm Formation

    PubMed Central

    Mashima, Izumi

    2015-01-01

    Dental plaque is a multispecies oral biofilm, the development of which is initiated by adherence of the pioneer Streptococcus spp. Oral Veillonella spp., including V. atypica, V. denticariosi, V. dispar, V. parvula, V. rogosae, and V. tobetsuensis, are known as early colonizers in oral biofilm formation. These species have been reported to coaggregate with Streptococcus spp. in a metabolic cooperation-dependent manner to form biofilms in human oral cavities, especially in the early stages of biofilm formation. However, in our previous study, Streptococcus gordonii showed biofilm formation to the greatest extent in the presence of V. tobetsuensis, without coaggregation between species. These results suggest that V. tobetsuensis produces signaling molecules that promote the proliferation of S. gordonii in biofilm formation. It is well known in many bacterial species that the quorum-sensing (QS) system regulates diverse functions such as biofilm formation. However, little is known about the QS system with autoinducers (AIs) with respect to Veillonella and Streptococcus spp. Recently, autoinducer 1 (AI-1) and AI-2 were detected and identified in the culture supernatants of V. tobetsuensis as strong signaling molecules in biofilm formation with S. gordonii. In particular, the supernatant from V. tobetsuensis showed the highest AI-2 activity among 6 oral Veillonella species, indicating that AIs, mainly AI-2, produced by V. tobetsuensis may be important factors and may facilitate biofilm formation of S. gordonii. Clarifying the mechanism that underlies the QS system between S. gordonii and V. tobetsuensis may lead to the development of novel methods for the prevention of oral infectious diseases caused by oral biofilms. PMID:25917902

  12. Role of the luxS gene in initial biofilm formation by Streptococcus mutans.

    PubMed

    He, Zhiyan; Liang, Jingping; Tang, Zisheng; Ma, Rui; Peng, Huasong; Huang, Zhengwei

    2015-01-01

    Quorum sensing (QS) is a process by which bacteria communicate with each other by secreting chemical signals called autoinducers (AIs). Among Gram-negative and Gram-positive bacteria, AI-2 synthesized by the LuxS enzyme is widespread. The aim of this study was to evaluate the effect of QS luxS gene on initial biofilm formation by Streptococcus mutans. The bacterial cell surface properties, including cell hydrophobicity (bacterial adherence to hydrocarbons) and aggregation, which are important for initial adherence during biofilm development, were investigated. The biofilm adhesion assay was evaluated by the MTT method. The structures of the 5-hour biofilms were observed by using confocal laser scanning microscopy, and QS-related gene expressions were investigated by real-time PCR. The luxS mutant strain exhibited higher biofilm adherence and aggregation, but lower hydrophobicity than the wild-type strain. The confocal laser scanning microscopy images revealed that the wild-type strain tended to form smaller aggregates with uniform distribution, whereas the luxS mutant strain aggregated into distinct clusters easily discernible in the generated biofilm. Most of the genes examined were downregulated in the biofilms formed by the luxS mutant strain, except the gtfB gene. QS luxS gene can affect the initial biofilm formation by S. mutans.

  13. Structure investigation of three hydrazones Schiff's bases by spectroscopic, thermal and molecular orbital calculations and their biological activities.

    PubMed

    Belal, Arafa A M; Zayed, M A; El-Desawy, M; Rakha, Sh M A H

    2015-03-05

    Three Schiff's bases AI (2(1-hydrazonoethyl)phenol), AII (2, 4-dibromo 6-(hydrazonomethyl)phenol) and AIII (2(hydrazonomethyl)phenol) were prepared as new hydrazone compounds via condensation reactions with molar ratio (1:1) of reactants. Firstly by reaction of 2-hydroxy acetophenone solution and hydrazine hydrate; it gives AI. Secondly condensation between 3,5-dibromo-salicylaldehyde and hydrazine hydrate gives AII. Thirdly condensation between salicylaldehyde and hydrazine hydrate gives AIII. The structures of AI-AIII were characterized by elemental analysis (EA), mass (MS), FT-IR and (1)H NMR spectra, and thermal analyses (TG, DTG, and DTA). The activation thermodynamic parameters, such as, ΔE(∗), ΔH(∗), ΔS(∗) and ΔG(∗) were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bond responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their anti-microbial potential.

  14. Structure investigation of three hydrazones Schiff's bases by spectroscopic, thermal and molecular orbital calculations and their biological activities

    NASA Astrophysics Data System (ADS)

    Belal, Arafa A. M.; Zayed, M. A.; El-Desawy, M.; Rakha, Sh. M. A. H.

    2015-03-01

    Three Schiff's bases AI (2(1-hydrazonoethyl)phenol), AII (2, 4-dibromo 6-(hydrazonomethyl)phenol) and AIII (2(hydrazonomethyl)phenol) were prepared as new hydrazone compounds via condensation reactions with molar ratio (1:1) of reactants. Firstly by reaction of 2-hydroxy acetophenone solution and hydrazine hydrate; it gives AI. Secondly condensation between 3,5-dibromo-salicylaldehyde and hydrazine hydrate gives AII. Thirdly condensation between salicylaldehyde and hydrazine hydrate gives AIII. The structures of AI-AIII were characterized by elemental analysis (EA), mass (MS), FT-IR and 1H NMR spectra, and thermal analyses (TG, DTG, and DTA). The activation thermodynamic parameters, such as, ΔE∗, ΔH∗, ΔS∗ and ΔG∗ were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bond responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their anti-microbial potential.

  15. Evidence based prevention of acute injuries during physical exercise in a WHO safe community

    PubMed Central

    Timpka, T; Lindqvist, K

    2001-01-01

    Objective—To evaluate a community based programme for evidence based prevention of injuries during physical exercise. Design—Quasi-experimental evaluation using an intervention population and a non-random control population. Participants—Study municipality (population 41 000) and control municipality (population 26 000) in Sweden. Main outcome measures—Morbidity rate for sports related injuries treated in the health care system; severity classification according to the abbreviated injury scale (AIS). Results—The total morbidity rate for sports related injuries in the study area decreased by 14% from 21 to 18 injuries per 1000 population years (odds ratio 0.87; 95% confidence interval (CI) 0.79 to 0.96). No tendency towards a decrease was observed in people over 40. The rate of moderately severe injury (AIS 2) decreased to almost half (odds ratio 0.58; 95% CI 0.50 to 0.68), whereas the rate of minor injuries (AIS 1) increased (odds ratio 1.22; 95% CI 1.06 to 1.40). The risk of severe injuries (AIS 3–6) remained constant. The rate of total sports injury in the control area did not change (odds ratio 0.93; 95% CI 0.81 to 1.07), and the trends in the study and control areas were not statistically significantly different. Conclusion—An evidence based prevention programme based on local safety rules and educational programmes can reduce the burden of injuries related to physical exercise in a community. Future studies need to look at adjusting the programme to benefit all age groups. Key Words: injuries; prevention; evaluation; community; intervention; safety promotion PMID:11157457

  16. A program for calculation of intrapulmonary shunts, blood-gas and acid-base values with a programmable calculator.

    PubMed

    Ruiz, B C; Tucker, W K; Kirby, R R

    1975-01-01

    With a desk-top, programmable calculator, it is now possible to do complex, previously time-consuming computations in the blood-gas laboratory. The authors have developed a program with the necessary algorithms for temperature correction of blood gases and calculation of acid-base variables and intrapulmonary shunt. It was necessary to develop formulas for the Po2 temperature-correction coefficient, the oxyhemoglobin-dissociation curve for adults (withe necessary adjustments for fetal blood), and changes in water vapor pressure due to variation in body temperature. Using this program in conjuction with a Monroe 1860-21 statistical programmable calculator, it is possible to temperature-correct pH,Pco2, and Po2. The machine will compute alveolar-arterial oxygen tension gradient, oxygen saturation (So2), oxygen content (Co2), actual HCO minus 3 and a modified base excess. If arterial blood and mixed venous blood are obtained, the calculator will print out intrapulmonary shunt data (Qs/Qt) and arteriovenous oxygen differences (a minus vDo2). There also is a formula to compute P50 if pH,Pco2,Po2, and measured So2 from two samples of tonometered blood (one above 50 per cent and one below 50 per cent saturation) are put into the calculator.

  17. (1)H NMR-Based Global Metabolic Studies of Pseudomonas aeruginosa upon Exposure of the Quorum Sensing Inhibitor Resveratrol.

    PubMed

    Chen, Tongtong; Sheng, Jiyang; Fu, Yonghong; Li, Minghui; Wang, Junsong; Jia, Ai-Qun

    2017-02-03

    Quorum sensing (QS) is a process of bacterial communication that has been a novel target for drug discovery. Pyocyanin quantification assay confirmed that resveratrol was an effective quorum sensing inhibitor (QSI) against Pseudomonas aeruginosa PAO1. In this study, the global metabolite changes of P. aeruginosa PAO1 exposed to QSI resveratrol were investigated by (1)H NMR spectroscopy. A total of 40 metabolites containing amino acids, organic acid, organic amine, and energy storage compounds were identified. The changed metabolic profile indicated that resveratrol influenced pathways including oxidative stress, protein synthesis, and energy metabolism. Oxidative stress could upregulate the expression of genes related to QS in P. aeruginosa. It suggested that resveratrol could inhibit the QS systems in P. aeruginosa PAO1 by relieving oxidative stress due to its antioxidant activity. On the other hand, resveratrol could attenuate the pathogenicity of P. aeruginosa PAO1 by disturbing the TCA cycle so that anaerobic respiration could suppress the virulence because anaerobiosis could induce the loss of cytotoxicity regulated by QS in P. aeruginosa. These findings deepened our comprehending of the metabolic responses of P. aeruginosa PAO1 to resveratrol and pinpointed the possible underlying mechanism of resveratrol's inhibition effect on QS in P. aeruginosa PAO1.

  18. Anatomical nuances of the internal carotid artery in relation to the quadrangular space.

    PubMed

    Dolci, Ricardo L L; Ditzel Filho, Leo F S; Goulart, Carlos R; Upadhyay, Smita; Buohliqah, Lamia; Lazarini, Paulo R; Prevedello, Daniel M; Carrau, Ricardo L

    2017-02-24

    OBJECTIVE The aim of this study was to evaluate the anatomical variations of the internal carotid artery (ICA) in relation to the quadrangular space (QS) and to propose a classification system based on the results. METHODS A total of 44 human cadaveric specimens were dissected endonasally under direct endoscopic visualization. During the dissection, the anatomical variations of the ICA and their relationship with the QS were noted. RESULTS The space between the paraclival ICAs (i.e., intercarotid space) can be classified as 1 of 3 different shapes (i.e., trapezoid, square, or hourglass) based on the trajectory of the ICAs. The ICA trajectories also directly influence the volumetric area of the QS. Based on its geometry, the QS was classified as one of the following: 1) Type A has the smallest QS area and is associated with a trapezoid intercarotid space, 2) Type B corresponds to the expected QS area (not minimized or enlarged) and is associated with a square intercarotid space, and 3) Type C has the largest QS area and is associated with an hourglass intercarotid space. CONCLUSIONS The different trajectories of the ICAs can modify the area of the QS and may be an essential parameter to consider for preoperative planning and defining the most appropriate corridor to reach Meckel's cave. In addition, ICA trajectories should be considered prior to surgery to avoid injuring the vessels.

  19. Structure-Activity Relationships of the Competence Stimulating Peptides (CSPs) in Streptococcus pneumoniae Reveal Motifs Critical for Intra-group and Cross-group ComD Receptor Activation.

    PubMed

    Yang, Yifang; Koirala, Bimal; Sanchez, Lucia A; Phillips, Naiya R; Hamry, Sally R; Tal-Gan, Yftah

    2017-03-10

    Streptococcus pneumoniae is a highly recombinogenic human pathogen that utilizes the competence stimulating peptide (CSP)-based quorum sensing (QS) circuitry to acquire antibiotic resistance genes from the environment and initiate its attack on the human host. Modulation of QS in this bacterium, either inhibition or activation, can therefore be used to attenuate S. pneumoniae infectivity and slow down pneumococcal resistance development. In this study, we set to determine the molecular mechanism that drives CSP:receptor binding and identify CSP-based QS modulators with distinct activity profiles. To this end, we conducted systematic replacement of the amino acid residues in the two major CSP signals (CSP1 and CSP2) and assessed the ability of the mutated analogs to modulate QS against both cognate and noncognate ComD receptors. We then evaluated the overall 3D structures of these analogs using circular dichroism (CD) to correlate between the structure and function of these peptides. Our CD analysis revealed a strong correlation between α-helicity and bioactivity for both specificity groups (CSP1 and CSP2). Furthermore, we identified the first pan-group QS activator and the most potent group-II QS inhibitor to date. These chemical probes can be used to study the role of QS in S. pneumoniae and as scaffolds for the design of QS-based anti-infective therapeutics against S. pneumoniae infections.

  20. Fungal Quorum Quenching: A Paradigm Shift for Energy Savings in Membrane Bioreactor (MBR) for Wastewater Treatment.

    PubMed

    Lee, Kibaek; Lee, Seonki; Lee, Sang Hyun; Kim, Sang-Ryoung; Oh, Hyun-Suk; Park, Pyung-Kyu; Choo, Kwang-Ho; Kim, Yea-Won; Lee, Jung-Kee; Lee, Chung-Hak

    2016-10-18

    In the last 30 years, the use of membrane bioreactors (MBRs) for advanced wastewater treatment and reuse have been expanded continuously, but they still suffer from excessive energy consumption resulting from the intrinsic problem of membrane biofouling. One of the major causes of biofouling in MBRs is bacterial quorum sensing (QS) via N-acylhomoserine lactones (AHLs) and/or autoinducer-2 (AI-2), enabling intra- and interspecies communications, respectively. In this study, we demonstrate that farnesol can substantially mitigate membrane biofouling in a MBR due to its quorum quenching (QQ) activity. When Candida albicans (a farnesol producing fungus) entrapping polymer beads (AEBs) were placed in the MBR, the rate of transmembrane pressure (TMP) rise-up was substantially decreased, even for lower aeration intensities. This finding corresponds to a specific aeration energy savings of approximately 40% (25% through the physical washing effect and a further 15% through the biological QQ effect of AEBs) compared to conventional MBRs without AEBs. A real-time RT-qPCR analysis revealed that farnesol secreted from C. albicans mitigated the biofilm formation in MBRs via the suppression of AI-2 QS. Successful control of biofouling and energy savings through fungal-to-bacterial QQ could be expanded to the plant scale for MBRs in wastewater treatment with economic feasibility.

  1. Gravel threshold of motion: a state function of sediment transport disequilibrium?

    NASA Astrophysics Data System (ADS)

    Johnson, Joel P. L.

    2016-08-01

    In most sediment transport models, a threshold variable dictates the shear stress at which non-negligible bedload transport begins. Previous work has demonstrated that nondimensional transport thresholds (τc*) vary with many factors related not only to grain size and shape, but also with characteristics of the local bed surface and sediment transport rate (qs). I propose a new model in which qs-dependent τc*, notated as τc(qs)*, evolves as a power-law function of net erosion or deposition. In the model, net entrainment is assumed to progressively remove more mobile particles while leaving behind more stable grains, gradually increasing τc(qs)* and reducing transport rates. Net deposition tends to fill in topographic lows, progressively leading to less stable distributions of surface grains, decreasing τc(qs)* and increasing transport rates. Model parameters are calibrated based on laboratory flume experiments that explore transport disequilibrium. The τc(qs)* equation is then incorporated into a simple morphodynamic model. The evolution of τc(qs)* is a negative feedback on morphologic change, while also allowing reaches to equilibrate to sediment supply at different slopes. Finally, τc(qs)* is interpreted to be an important but nonunique state variable for morphodynamics, in a manner consistent with state variables such as temperature in thermodynamics.

  2. Effect of Cinnamon Oil on Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa.

    PubMed

    Kalia, Manmohit; Yadav, Vivek Kumar; Singh, Pradeep Kumar; Sharma, Deepmala; Pandey, Himanshu; Narvi, Shahid Suhail; Agarwal, Vishnu

    2015-01-01

    Quorum sensing (QS) is a system of stimuli and responses in bacterial cells governed by their population density, through which they regulate genes that control virulence factors and biofilm formation. Despite considerable research on QS and the discovery of new antibiotics, QS-controlled biofilm formation by microorganisms in clinical settings has remained a problem because of nascent drug resistance, which requires screening of diverse compounds for anti-QS activities. Cinnamon is a dietary phytochemical that is traditionally used to remedy digestive problems and assorted contagions, which suggests that cinnamon might contain chemicals that can hinder the QS process. To test this hypothesis, the anti-QS activity of cinnamon oil against P. aeruginosa was tested, measured by the inhibition of biofilm formation and other QS-associated phenomena, including virulence factors such as pyocyanin, rhamnolipid, protease, alginate production, and swarming activity. To this end, multiple microscopy analyses, including light, scanning electron and confocal microscopy, revealed the ability of cinnamon oil to inhibit P. aeruginosa PAO1 biofilms and their accompanying extracellular polymeric substances. This work is the first to demonstrate that cinnamon oil can influence various QS-based phenomena in P. aeruginosa PAO1, including biofilm formation.

  3. Effect of Cinnamon Oil on Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa

    PubMed Central

    Kalia, Manmohit; Yadav, Vivek Kumar; Singh, Pradeep Kumar; Sharma, Deepmala; Pandey, Himanshu; Narvi, Shahid Suhail; Agarwal, Vishnu

    2015-01-01

    Quorum sensing (QS) is a system of stimuli and responses in bacterial cells governed by their population density, through which they regulate genes that control virulence factors and biofilm formation. Despite considerable research on QS and the discovery of new antibiotics, QS-controlled biofilm formation by microorganisms in clinical settings has remained a problem because of nascent drug resistance, which requires screening of diverse compounds for anti-QS activities. Cinnamon is a dietary phytochemical that is traditionally used to remedy digestive problems and assorted contagions, which suggests that cinnamon might contain chemicals that can hinder the QS process. To test this hypothesis, the anti-QS activity of cinnamon oil against P. aeruginosa was tested, measured by the inhibition of biofilm formation and other QS-associated phenomena, including virulence factors such as pyocyanin, rhamnolipid, protease, alginate production, and swarming activity. To this end, multiple microscopy analyses, including light, scanning electron and confocal microscopy, revealed the ability of cinnamon oil to inhibit P. aeruginosa PAO1 biofilms and their accompanying extracellular polymeric substances. This work is the first to demonstrate that cinnamon oil can influence various QS-based phenomena in P. aeruginosa PAO1, including biofilm formation. PMID:26263486

  4. Cyanidin inhibits quorum signalling pathway of a food borne opportunistic pathogen.

    PubMed

    Gopu, Venkadesaperumal; Shetty, Prathapkumar Halady

    2016-02-01

    Quorum sensing (QS) is the process of population dependent cell to cell communication used by bacteria to regulate their phenotypic characteristics. Key virulence factors that determine the bacterial pathogenicity and food spoilage were found to be regulated by QS mechanism. Hence, disrupting the QS signaling pathway could be an attractive strategy to manage food borne pathogens. In the current study, QS inhibitory activity of a naturally occurring anthocyanin-cyanidin and its anti-biofilm property were assessed against an opportunistic pathogen Klebsiella pneumoniae, using a bio-sensor strain. Further, QS inhibitory property of a naturally occurring anthocyanin cyanidin was further confirmed using in-silico techniques like molecular docking and molecular dynamics simulation studies. Cyanidin at sub-lethal dose significantly inhibited QS-dependent phenotypes like violacein production (73.96 %), biofilm formation (72.43 %), and exopolysaccharide production (68.65) in a concentration-dependent manner. Cyanidin enhanced the sensitivity of test pathogen to conventional antibiotics in a synergistic manner. Molecular docking analysis revealed that cyanidin binds more rigidly with LasR receptor protein than the signaling compound with a docking score of -9.13 Kcal/mol. Molecular dynamics simulation predicted that QS inhibitory activity occurs through the conformational changes between the receptor and cyanidin complex. Our results indicate that cyanidin, can be a potential QS based antibiofilm and antibacterial agent for food borne pathogens.

  5. Bioassays of quorum sensing compounds using Agrobacterium tumefaciens and Chromobacterium violaceum.

    PubMed

    Chu, Weihua; Vattem, Dhiraj A; Maitin, Vatsala; Barnes, Mary B; McLean, Robert J C

    2011-01-01

    In most bacteria, a global level of regulation exists involving intercellular communication via the production and response to cell density-dependent signal molecules. This cell density-dependent regulation has been termed quorum sensing (QS). QS is a global regulator, which has been associated with a number of important features in bacteria including virulence regulation and biofilm formation. Consequently, there is considerable interest in understanding, detecting, and inhibiting QS. Acyl homoserine lactones (acyl HSLs) are used as extracellular QS signals by a variety of Gram-negative bacteria. Chromobacterium violaceum, a Gram-negative bacterium commonly found in soil and water, produces the characteristic purple pigment violacein, the production of which is regulated by acyl HSL-mediated QS. Based on this readily observed pigmentation phenotype, C. violaceum strains can be used to detect various aspects of acyl HSL-mediated QS activity. In another commonly used bioassay organism, Agrobacterium tumefaciens, QS can be detected by the use of a reporter gene such as lacZ. Here, we describe several commonly used approaches incorporating C. violaceum and A. tumefaciens that can be used to detect acyl HSLs and QS inhibition.

  6. Role of Pseudomonas aeruginosa quorum sensing (QS) molecules on the viability and cytokine profile of human mesenchymal stem cells.

    PubMed

    Holban, Alina-Maria; Bleotu, Coralia; Chifiriuc, Mariana Carmen; Bezirtzoglou, Eugenia; Lazar, Veronica

    2014-02-15

    Pseudomonas aeruginosa infections represent one of the major threats for injured or transplanted lungs and for their healing. Considering that the mesenchymal stem cells (MSCs) are a major tool for the regenerative medicine, including therapy of lung damaging diseases, the aim of this paper was to investigate the effects of P. aeruginosa quorum sensing signaling molecules (QSSMs) on human MSCs death signaling pathways and cytokine profile. Our data revealed that N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), N-butanoyl-L-homoserine lactone (C4-HSL), 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), and its precursor, 2-heptyl-4-quinolone (HHQ), significantly impact on several core signaling mechanisms of MSCs in a specific and time-dependent manner. Even if all tested autoinducers interfered with the MSCs apoptotic genes expression, only OdDHL and HHQ significantly promoted MSCs apoptosis, by 14- and 23-fold respectively, this aspect being confirmed by the flow cytometry assay. The tested QSSMs induced a heterogeneous cytokine profile of the treated MSCs. The level of IL-1β was increased by OdDHL, IL-8 production was stimulated by all tested autoinducers, IL-6 was modulated mostly by PQS and IL-10 by HHQ. The significant influence of the purified bacterial autoinducers on the MSCs signaling pathways may suggest that the accumulation of these mediators could interfere with the normal function of these cells in the human body, and eventually, impair or abolish the success of the stem cells therapy during P. aeruginosa infections.

  7. Role of Pseudomonas aeruginosa quorum sensing (QS) molecules on the viability and cytokine profile of human mesenchymal stem cells

    PubMed Central

    Holban, Alina-Maria; Bleotu, Coralia; Chifiriuc, Mariana Carmen; Bezirtzoglou, Eugenia; Lazar, Veronica

    2014-01-01

    Pseudomonas aeruginosa infections represent one of the major threats for injured or transplanted lungs and for their healing. Considering that the mesenchymal stem cells (MSCs) are a major tool for the regenerative medicine, including therapy of lung damaging diseases, the aim of this paper was to investigate the effects of P. aeruginosa quorum sensing signaling molecules (QSSMs) on human MSCs death signaling pathways and cytokine profile. Our data revealed that N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), N-butanoyl-L-homoserine lactone (C4-HSL), 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), and its precursor, 2-heptyl-4-quinolone (HHQ), significantly impact on several core signaling mechanisms of MSCs in a specific and time-dependent manner. Even if all tested autoinducers interfered with the MSCs apoptotic genes expression, only OdDHL and HHQ significantly promoted MSCs apoptosis, by 14- and 23-fold respectively, this aspect being confirmed by the flow cytometry assay. The tested QSSMs induced a heterogeneous cytokine profile of the treated MSCs. The level of IL-1β was increased by OdDHL, IL-8 production was stimulated by all tested autoinducers, IL-6 was modulated mostly by PQS and IL-10 by HHQ. The significant influence of the purified bacterial autoinducers on the MSCs signaling pathways may suggest that the accumulation of these mediators could interfere with the normal function of these cells in the human body, and eventually, impair or abolish the success of the stem cells therapy during P. aeruginosa infections. PMID:24398422

  8. Pulsating Electrohydrodynamic Cone-Jets: from Choked Jet to Oscillating Cone

    NASA Astrophysics Data System (ADS)

    Bober, David; Chen, Chuan-Hua

    2011-11-01

    Pulsating cone-jets occur in a variety of electrostatic spraying and printing systems. We report an experimental study of the pulsation frequency to reconcile two models based on a choked jet and an oscillating cone, respectively. The two regimes are demarcated by the ratio of the supplied flow rate (Qs) to the minimum flow rate (Qm) required for a steady Taylor cone-jet. When Qs Qs /Qm . When Qs >Qm , the Taylor cone anchored at the nozzle experiences a capillary oscillation analogous to the Rayleigh mode of a free drop; the pulsation frequency in the oscillating cone regime plateaus to the capillary oscillation frequency which is independent of Qs /Qm .

  9. Inhibition of biofilm development and spoilage potential of Shewanella baltica by quorum sensing signal in cell-free supernatant from Pseudomonas fluorescens.

    PubMed

    Zhao, Aifei; Zhu, Junli; Ye, Xiaofeng; Ge, Yangyang; Li, Jianrong

    2016-08-02

    The objective of this study was to in vitro evaluate the effect of a cell-free supernatant (CFS) containing quorum sensing (QS) signal of Pseudomonas fluorescens on the growth, biofilm development and spoilage potential of Shewanella baltica, and preliminarily assess the interactive influences of various chemically synthesized autoinducers on spoilage phenotypes of S. baltica. PF01 strain isolated from spoiled Pseudosciaen crocea was identified P. fluorescens. The addition of 25% and 50% CFS to S. baltica culture had no effect on the growth rate during the lag and exponential phase, however, caused cell decline during the stationary phase. The presence of CFS from P. fluorescens significantly inhibited biofilm development, and greatly decreased the production of trimethylamine (TMA) and biogenic amino in S. baltica. Various signal molecules of QS in the CFS of P. fluorescens culture were detected, including seven N-acyl-l-homoserine lactones (AHLs), autoinducer-2 (AI-2) and two diketopiperazines (DKPs). Exogenous supplement of synthesized seven AHLs containing in the CFS decreased biofilm formation and TMA production in S. baltica, while exposure to exogenous cyclo-(l-Pro-l-Leu) was showed to promote spoilage potential, which revealed that S. baltica also sense the two QS molecules. Furthermore, the stimulating effect of cyclo-(l-Pro-l-Leu) was affected when AHL was simultaneously added, suggesting that the inhibitory activity of spoilage phenotypes in S. baltica might be attributed to a competitive effect of these QS compounds in the CFS of P. fluorescens. The present studies provide a good basis for future research on the role of QS in the regulation of spoilage microbial flora.

  10. The establishment of a library screening method based on yeast two-hybrid system and its use to determine the potential interactions of liver proteins in ayu, Plecoglossus altivelis.

    PubMed

    Shi, Y H; Chen, J; Li, C H; Yang, H Y; Lu, X J

    2011-01-01

    Knowledge of specific protein-protein interaction (PPI) is an important component in understanding biological processes and regulatory mechanisms. A library to library screening method (LLS) was established based on yeast two-hybrid (YTH) system in this research, and applied to study the PPIs in ayu liver. In total, 23 out of 55 interaction pairs were found positive through phenotypic identification, with a positive rate of 41.8%. Of the 11 unique PPIs, 9 interactions including FGB/FGG, CaM/Spna2, C9/Apo-AI-1, α₂M/Ft, RPL10/RPL5, C8α/C9, FGG/Apo-AI-1, LECT2/Tf, and Apo-AI-2/C9 were previously reported. The other two PPIs including FGG/CLR and Wap65/C3 are novel, and in vitro co-immunoprecipitation (co-IP) experiments further confirmed these interactions. FGG/CLR interaction might play a role in regulating the inflammatory response. The interaction between Wap65 and C3 hints that Wap65 might function through the complement activation pathways when microbial infection occurs.

  11. Quorum sensing in the context of food microbiology.

    PubMed

    Skandamis, Panagiotis N; Nychas, George-John E

    2012-08-01

    Food spoilage may be defined as a process that renders a product undesirable or unacceptable for consumption and is the outcome of the biochemical activity of a microbial community that eventually dominates according to the prevailing ecological determinants. Although limited information are reported, this activity has been attributed to quorum sensing (QS). Consequently, the potential role of cell-to-cell communication in food spoilage and food safety should be more extensively elucidated. Such information would be helpful in designing approaches for manipulating these communication systems, thereby reducing or preventing, for instance, spoilage reactions or even controlling the expression of virulence factors. Due to the many reports in the literature on the fundamental features of QS, e.g., chemistry and definitions of QS compounds, in this minireview, we only allude to the types and chemistry of QS signaling molecules per se and to the (bioassay-based) methods of their detection and quantification, avoiding extensive documentation. Conversely, we attempt to provide insights into (i) the role of QS in food spoilage, (ii) the factors that may quench the activity of QS in foods and review the potential QS inhibitors that might "mislead" the bacterial coordination of spoilage activities and thus may be used as biopreservatives, and (iii) the future experimental approaches that need to be undertaken in order to explore the "gray" or "black" areas of QS, increase our understanding of how QS affects microbial behavior in foods, and assist in finding answers as to how we can exploit QS for the benefit of food preservation and food safety.

  12. Quorum Sensing in the Context of Food Microbiology

    PubMed Central

    Skandamis, Panagiotis N.

    2012-01-01

    Food spoilage may be defined as a process that renders a product undesirable or unacceptable for consumption and is the outcome of the biochemical activity of a microbial community that eventually dominates according to the prevailing ecological determinants. Although limited information are reported, this activity has been attributed to quorum sensing (QS). Consequently, the potential role of cell-to-cell communication in food spoilage and food safety should be more extensively elucidated. Such information would be helpful in designing approaches for manipulating these communication systems, thereby reducing or preventing, for instance, spoilage reactions or even controlling the expression of virulence factors. Due to the many reports in the literature on the fundamental features of QS, e.g., chemistry and definitions of QS compounds, in this minireview, we only allude to the types and chemistry of QS signaling molecules per se and to the (bioassay-based) methods of their detection and quantification, avoiding extensive documentation. Conversely, we attempt to provide insights into (i) the role of QS in food spoilage, (ii) the factors that may quench the activity of QS in foods and review the potential QS inhibitors that might “mislead” the bacterial coordination of spoilage activities and thus may be used as biopreservatives, and (iii) the future experimental approaches that need to be undertaken in order to explore the “gray” or “black” areas of QS, increase our understanding of how QS affects microbial behavior in foods, and assist in finding answers as to how we can exploit QS for the benefit of food preservation and food safety. PMID:22706047

  13. The CpAL quorum sensing system regulates production of hemolysins CPA and PFO to build Clostridium perfringens biofilms.

    PubMed

    Vidal, Jorge E; Shak, Joshua R; Canizalez-Roman, Adrian

    2015-06-01

    Clostridium perfringens strains produce severe diseases, including myonecrosis and enteritis necroticans, in humans and animals. Diseases are mediated by the production of potent toxins that often damage the site of infection, e.g., skin epithelium during myonecrosis. In planktonic cultures, the regulation of important toxins, such as CPA, CPB, and PFO, is controlled by the C. perfringens Agr-like (CpAL) quorum sensing (QS) system. Strains also encode a functional LuxS/AI-2 system. Although C. perfringens strains form biofilm-like structures, the regulation of biofilm formation is poorly understood. Therefore, our studies investigated the role of CpAL and LuxS/AI-2 QS systems and of QS-regulated factors in controlling the formation of biofilms. We first demonstrate that biofilm production by reference strains differs depending on the culture medium. Increased biomass correlated with the presence of extracellular DNA in the supernatant, which was released by lysis of a fraction of the biofilm population and planktonic cells. Whereas ΔagrB mutant strains were not able to produce biofilms, a ΔluxS mutant produced wild-type levels. The transcript levels of CpAL-regulated cpa and pfoA genes, but not cpb, were upregulated in biofilms compared to planktonic cultures. Accordingly, Δcpa and ΔpfoA mutants, in type A (S13) or type C (CN3685) backgrounds, were unable to produce biofilms, whereas CN3685Δcpb made wild-type levels. Biofilm formation was restored in complemented Δcpa/cpa and ΔpfoA/pfoA strains. Confocal microscopy studies further detected CPA partially colocalizing with eDNA on the biofilm structure. Thus, CpAL regulates biofilm formation in C. perfringens by increasing levels of certain toxins required to build biofilms.

  14. The CpAL Quorum Sensing System Regulates Production of Hemolysins CPA and PFO To Build Clostridium perfringens Biofilms

    PubMed Central

    Shak, Joshua R.; Canizalez-Roman, Adrian

    2015-01-01

    Clostridium perfringens strains produce severe diseases, including myonecrosis and enteritis necroticans, in humans and animals. Diseases are mediated by the production of potent toxins that often damage the site of infection, e.g., skin epithelium during myonecrosis. In planktonic cultures, the regulation of important toxins, such as CPA, CPB, and PFO, is controlled by the C. perfringens Agr-like (CpAL) quorum sensing (QS) system. Strains also encode a functional LuxS/AI-2 system. Although C. perfringens strains form biofilm-like structures, the regulation of biofilm formation is poorly understood. Therefore, our studies investigated the role of CpAL and LuxS/AI-2 QS systems and of QS-regulated factors in controlling the formation of biofilms. We first demonstrate that biofilm production by reference strains differs depending on the culture medium. Increased biomass correlated with the presence of extracellular DNA in the supernatant, which was released by lysis of a fraction of the biofilm population and planktonic cells. Whereas ΔagrB mutant strains were not able to produce biofilms, a ΔluxS mutant produced wild-type levels. The transcript levels of CpAL-regulated cpa and pfoA genes, but not cpb, were upregulated in biofilms compared to planktonic cultures. Accordingly, Δcpa and ΔpfoA mutants, in type A (S13) or type C (CN3685) backgrounds, were unable to produce biofilms, whereas CN3685Δcpb made wild-type levels. Biofilm formation was restored in complemented Δcpa/cpa and ΔpfoA/pfoA strains. Confocal microscopy studies further detected CPA partially colocalizing with eDNA on the biofilm structure. Thus, CpAL regulates biofilm formation in C. perfringens by increasing levels of certain toxins required to build biofilms. PMID:25824838

  15. Mechanistic platform knowledge of concomitant sugar uptake in Escherichia coli BL21(DE3) strains

    PubMed Central

    Wurm, David J.; Hausjell, Johanna; Ulonska, Sophia; Herwig, Christoph; Spadiut, Oliver

    2017-01-01

    When producing recombinant proteins, the use of Escherichia coli strain BL21(DE3) in combination with the T7-based pET-expression system is often the method of choice. In a recent study we introduced a mechanistic model describing the correlation of the specific glucose uptake rate (qs,glu) and the corresponding maximum specific lactose uptake rate (qs,lac,max) for a pET-based E. coli BL21(DE3) strain producing a single chain variable fragment (scFv). We showed the effect of qs,lac,max on productivity and product location underlining its importance for recombinant protein production. In the present study we investigated the mechanistic qs,glu/qs,lac,max correlation for four pET-based E. coli BL21(DE3) strains producing different recombinant products and thereby proved the mechanistic model to be platform knowledge for E. coli BL21(DE3). However, we found that the model parameters strongly depended on the recombinant product. Driven by this observation we tested different dynamic bioprocess strategies to allow a faster investigation of this mechanistic correlation. In fact, we succeeded and propose an experimental strategy comprising only one batch cultivation, one fed-batch cultivation as well as one dynamic experiment, to reliably determine the mechanistic model for qs,glu/qs,lac,max and get trustworthy model parameters for pET-based E. coli BL21(DE3) strains which are the basis for bioprocess development. PMID:28332595

  16. Structure-based virtual screening and biological evaluation of LuxT inhibitors for targeting quorum sensing through an in vitro biofilm formation

    NASA Astrophysics Data System (ADS)

    Sasikala, Dakshinamurthy; Jeyakanthan, Jeyaraman; Srinivasan, Pappu

    2017-01-01

    The LuxT regulator protein is a potential drug target for regulating quorum sensing (QS) in Vibrio alginolyticus. There is no substantiation of a 3D structure of LuxT in this particular species, thus the 3D model was constructed using molecular modeling and its stability was verified under solvation effect using molecular dynamics simulation. Further, exploration of the drug candidate against the LuxT binding site through structure-based approaches identified four Bitter compounds, viz., quercetin, cnicin, 5, 5‧ methylenedisalicyclic acid, and flufenamic acid with high docking score and optimum binding energy. Remarkably, these compounds established agreeable interactions with the amino acid residues Phe67, Asp63, Thr59, Gly64, Ile66, Phe99, Arg123, Asn119, and Gly120; which are found to play a vital role in the LuxT mechanistic inhibition. In addition to the scoring and energy parameters, MD simulation and ADME prediction suggested that the proposed compounds may be promising drug candidates against V. alginolyticus. Therefore, the lead candidate quercetin was scrutinized to validate its potential in biofilm inhibition of V. alginolyticus. The results revealed that the compound had better efficacy in biofilm destruction; as a consequence, there was a significant effect on motility and EPS synthesis at an effective concentration of 100 μM, which was further confirmed by microscopic studies. Hence, the present study will provide an insight into the design of high potent drug molecules to combat dreadful pathogenic diseases caused by V. alginolyticus.

  17. The effect of hot-rolling on chill-cast AI-AI3Ni, chill-cast AI-AI2Cu, and Unidirectionally Solidified AI-AI3Ni Eutectic Alloys

    NASA Astrophysics Data System (ADS)

    Jardine, F. S. J.; Cantor, B.

    1986-11-01

    The effect of hot-rolling on the mechanical properties and microstructures of chill-cast Al-Al3Ni, chill-cast Al-Al2Cu, and unidirectionally solidified Al-Al3Ni eutectic alloys has been studied. The chill-cast eutectic alloys were produced by casting into preheated mild steel molds placed on copper chills. This system promoted growth along the length of the ingot and not radially from the mold wall. Cellular microstructures resulted with good alignment of Al3Ni fibers or Al2Cu lamellae within the cells and an interfiber/lamellar spacing of ~ 1 /urn. In contrast, the Al-Al3Ni eutectic alloy was also unidirectionally solidified at a growth rate of 3 x 10-1 m s-1 in a conventional horizontal crystal grower. This produced well-aligned Al3Ni fibers with an interfiber spacing of 1.2 ώm. Both the unidirectionally solidified and chill-cast Al-Al3Ni eutectic alloy can be hot-rolled at 773 K to reductions in area of greater than 95 pct. Deformation was achieved by Al3Ni fiber fracturing followed by separation of the broken fiber fragments in the rolling direction. Additionally, for the chill-cast eutectic the cellular microstructure disappeared and the Al3Ni fibers were homogeneously distributed throughout the matrix, after area reductions of 60 to 70 pct. In both cases, the eutectic microstructure was deformed with a constant volume fraction of Al3Ni/unit volume being maintained during rolling. The chill-cast Al-Al2Cu eutectic alloy can be hot-rolled at 773 K to an area reduction of ~50 pct, after the continuous brittle Al2Cu phase within the cells has been ‘broken up’ by coarsening at high temperature. The variations of room temperature tensile properties for the chill-cast and unidirectionally solidified eutectic alloys were measured as a function of reduction of thickness during hot-rolling and the results were compared with predicted strengths from discontinuous fiber reinforcement theory.

  18. Quercetin Influences Quorum Sensing in Food Borne Bacteria: In-Vitro and In-Silico Evidence

    PubMed Central

    Gopu, Venkadesaperumal; Meena, Chetan Kumar; Shetty, Prathapkumar Halady

    2015-01-01

    Quorum sensing (QS) plays a vital role in regulating the virulence factor of many food borne pathogens, which causes severe public health risk. Therefore, interrupting the QS signaling pathway may be an attractive strategy to combat microbial infections. In the current study QS inhibitory activity of quercetin and its anti-biofilm property was assessed against food-borne pathogens using a bio-sensor strain. In addition in-silico techniques like molecular docking and molecular dynamics simulation studies were applied to screen the quercetin’s potentiality as QS inhibitor. Quercetin (80μg/ml) showed the significant reduction in QS-dependent phenotypes like violacein production, biofilm formation, exopolysaccharide (EPS) production, motility and alginate production in a concentration-dependent manner. Synergistic activity of conventional antibiotics with quercetin enhanced the susceptibility of all tested pathogens. Furthermore, Molecular docking analysis revealed that quercetin binds more rigidly with LasR receptor protein than the signaling compound with docking score of -9.17Kcal/mol. Molecular dynamics simulation predicted that QS inhibitory activity of quercetin occurs through the conformational changes between the receptor and quercetin complex. Above findings suggest that quercetin can act as a competitive inhibitor for signaling compound towards LasR receptor pathway and can serve as a novel QS-based antibacterial/anti-biofilm drug to manage food-borne pathogens. PMID:26248208

  19. Chitosan nanoparticles enhances the anti-quorum sensing activity of kaempferol.

    PubMed

    Ilk, Sedef; Sağlam, Necdet; Özgen, Mustafa; Korkusuz, Feza

    2017-01-01

    Quorum sensing (QS) is a cell density dependent expression of species in bacteria mediated by compounds called autoinducers (AI). Several processes responsible for successful establishment of bacterial infection are mediated by QS. Inhibition of QS is therefore being considered as a new target for antimicrobial chemotherapy. Flavonoid compounds are strong antioxidant and antimicrobial agents but their applications are limited due to their poor dissolution and bioavailability. Our objective was to investigate the effect of kaempferol loaded chitosan nanoparticles on modulating QS mediated by AI in model bioassay test systems. For this purpose, kaempferol loaded nanoparticles were synthesized and characterized in terms of hydrodynamic diameter, hydrogen bonding, amorphous transformation and antioxidant activity. QS inhibition in time dependent manner of nanoparticles was measured in violacein pigment producing using the biosensor strain Chromobacterium violaceum CV026 mediated by AI known as acylated homoserine lactone (AHL). Our results indicated that the average kaempferol loaded chitosan/TPP nanoparticle size and zeta potential were 192.27±13.6nm and +35mV, respectively. The loading and encapsulation efficiency of kaempferol into chitosan/TPP nanoparticles presented higher values between 78 and 93%. Kaempferol loaded chitosan/TPP nanoparticle during the 30 storage days significantly inhibited the production of violacein pigment in Chromobacterium violaceum CV026. The observation that kaempferol encapsulated chitosan nanoparticles can inhibit QS related processes opens up an exciting new strategy for antimicrobial chemotherapy as stable QS-based anti-biofilm agents.

  20. Software Tools for Emittance Measurement and Matching for 12 GeV CEBAF

    SciTech Connect

    Turner, Dennis L.

    2016-05-01

    This paper discusses model-driven setup of the Continuous Electron Beam Accelerator Facility (CEBAF) for the 12GeV era, focusing on qsUtility. qsUtility is a set of software tools created to perform emittance measurements, analyze those measurements, and compute optics corrections based upon the measurements.qsUtility was developed as a toolset to facilitate reducing machine configuration time and reproducibility by way of an accurate accelerator model, and to provide Operations staff with tools to measure and correct machine optics with little or no assistance from optics experts.

  1. A novel method for the quantitation of gingerol glucuronides in human plasma or urine based on stable isotope dilution assays.

    PubMed

    Schoenknecht, Carola; Andersen, Gaby; Schieberle, Peter

    2016-11-15

    The bio-active compounds of ginger (Zingiber officinale Roscoe), the gingerols, are gaining considerable attention due to their numerous beneficial health effects. In order to elucidate the physiological relevance of the ascribed effects their bioavailability has to be determined taking their metabolization into account. To quantitate in vivo generated [6]-, [8]- and [10]-gingerol glucuronides in human plasma and urine after ginger tea consumption, a simultaneous and direct liquid chromatography-tandem mass spectrometry method based on stable isotope dilution assays was established and validated. The respective references as well as the isotopically labeled substances were synthesized and characterized by mass spectrometry and NMR. Selective isolation of gingerol glucuronides from human plasma and urine by a mixed-phase anion-exchange SPE method led to recovery rates between 80.8 and 98.2%. LC-MS/MS analyses in selected reaction monitoring modus enabled a highly sensitive quantitation of gingerol glucuronides with LoQs between 3.9-9.8nmol/L in plasma and 39.3-161.1nmol/L in urine. The method precision in plasma and urine varied in the range±15%, whereas the intra-day accuracy in plasma and urine showed values between 78 and 122%. The developed method was then applied to a pilot study in which two volunteers consumed one liter ginger tea. Pharmacokinetic parameters like the maximum concentration (cmax), the time to reach cmax (tmax), area under the curve (AUC), elimination rate constant (kel) and elimination half-life (t1/2) were calculated from the concentration-time curve of each gingerol glucuronide. The obtained results will enable more detailed investigation of gingerol glucuronides as bioactives in their physiologically relevant concentrations.

  2. Moving Up the CMMI Capability and Maturity Levels Using Simulation

    DTIC Science & Technology

    2008-01-01

    grained process enactment [Drappa 2000, Scacchi 1999, Scacchi 1990]. Qualitative simulation (QS): QS has been used to model software evolutionary...Brian G., & Smith- Daniels , Dwight E. “System Dynamics Modeling Applied to Software Outsourcing Decision Support.” Software Process: Improvement and...diss., Arizona State University, 1998. [ Scacchi 1990] Scacchi , W. & Mi, P. “A Knowledge-Based Environment for Modeling and Simulating Software

  3. Extraction, purification and identification of bacterial signal molecules based on N‐acyl homoserine lactones

    PubMed Central

    Wang, Jianhua; Quan, Chunshan; Wang, Xue; Zhao, Pengchao; Fan, Shengdi

    2011-01-01

    Summary Bacteria possess an extraordinary repertoire for intercellular communication and social behaviour. This repertoire for bacterial communication, termed as quorum sensing (QS), depends on specific diffusible signal molecules. There are many different kinds of signal molecules in the bacterial community. Among those signal molecules, N‐acyl homoserine lactones (HSLs, in other publications also referred to as AHLs, acy‐HSLs etc.) are often employed as QS signal molecules for many Gram‐negative bacteria. Due to the specific structure and tiny amount of those HSL signal molecules, the characterization of HSLs has been the subject of extensive investigations in the last decades and has become a paradigm for bacteria intercellular signalling. In this article, different methods, including extraction, purification and characterization of HSLs, are reviewed. The review provides an insight into identification and characterization of new HSLs and other signal molecules for bacterial intercellular communication. PMID:21375695

  4. Acyl-Homoserine Lactone Quorum Sensing in the Roseobacter Clade

    PubMed Central

    Zan, Jindong; Liu, Yue; Fuqua, Clay; Hill, Russell T.

    2014-01-01

    Members of the Roseobacter clade are ecologically important and numerically abundant in coastal environments and can associate with marine invertebrates and nutrient-rich marine snow or organic particles, on which quorum sensing (QS) may play an important role. In this review, we summarize current research progress on roseobacterial acyl-homoserine lactone-based QS, particularly focusing on three relatively well-studied representatives, Phaeobacter inhibens DSM17395, the marine sponge symbiont Ruegeria sp. KLH11 and the dinoflagellate symbiont Dinoroseobacter shibae. Bioinformatic survey of luxI homologues revealed that over 80% of available roseobacterial genomes encode at least one luxI homologue, reflecting the significance of QS controlled regulatory pathways in adapting to the relevant marine environments. We also discuss several areas that warrant further investigation, including studies on the ecological role of these diverse QS pathways in natural environments. PMID:24402124

  5. Research on a Queue Scheduling Algorithm in Wireless Communications Network

    NASA Astrophysics Data System (ADS)

    Yang, Wenchuan; Hu, Yuanmei; Zhou, Qiancai

    This paper proposes a protocol QS-CT, Queue Scheduling Mechanism based on Multiple Access in Ad hoc net work, which adds queue scheduling mechanism to RTS-CTS-DATA using multiple access protocol. By endowing different queues different scheduling mechanisms, it makes networks access to the channel much more fairly and effectively, and greatly enhances the performance. In order to observe the final performance of the network with QS-CT protocol, we simulate it and compare it with MACA/C-T without QS-CT protocol. Contrast to MACA/C-T, the simulation result shows that QS-CT has greatly improved the throughput, delay, rate of packets' loss and other key indicators.

  6. Study of pressure induced polyamorphic transition in Ce-based ternary BMG using in situ x-ray scattering and electrical conductivity measurement

    NASA Astrophysics Data System (ADS)

    Chen, J.; Ma, C.; Tang, R.; Li, L.; Liu, H.; Gao, C.; Yang, W.

    2015-12-01

    In situ high energy x-ray scattering and electrical conductivity measurements on Ce70Al10Cu20 bulk metallic glass have been conducted using a diamond anvil cell (DAC) in conjunction with synchrotron x-rays or a laboratory electrical measurement system. The relative volumetric change (V/V0) as a function of pressure is inferred using the first sharp diffraction peak (FSDP) and the universal fractional noncubic power law[1]. The result indicates a pressure-induced polyamorphic transition at about 4 GPa in the ternary system. While the observed pressure of such polyamorphic transition in the Ce-base binary BMG is not very sensitive to its composition based on some of the previous studies[2, 3], this study indicates that such transition pressure increases considerably when a new component is added to the system. In the electrical conductivity measurement, a significant resistance change was observed in the pressure range coupled to polyamorphic transition. More discussions will be given regarding the electrical conductivity behavior of this system under high pressure to illustrate the delocalization of 4f electrons as the origin of the observed polyamorphic transition. References: 1. Zeng Q, Kono Y, Lin Y, Zeng Z, Wang J, Sinogeikin SV, Park C, Meng Y, Yang W, Mao H-K (2014) Universal fractional noncubic power law for density of metallic glasses. Physical Review Letters 112: 185502-185502 2. Zeng Q-S, Ding Y, Mao WL, Yang W, Sinogeikin SV, Shu J, Mao H-K, Jiang JZ (2010) Origin of pressure-induced polyamorphism in Ce75Al25 metallic glass. Physical Review Letters 104: 105702-105702 3. Sheng HW, Liu HZ, Cheng YQ, Wen J, Lee PL, Luo WK, Shastri SD, Ma E (2007) Polyamorphism in a metallic glass. Nature Materials DOI: 10.1038/nmat1839.

  7. Applications of quorum sensing in biotechnology.

    PubMed

    Choudhary, Swati; Schmidt-Dannert, Claudia

    2010-05-01

    Many unicellular microorganisms use small signaling molecules to determine their local concentration. The processes involved in the production and recognition of these signals are collectively known as quorum sensing (QS). This form of cell-cell communication is used by unicellular microorganisms to co-ordinate their activities, which allows them to function as multi-cellular systems. Recently, several groups have demonstrated artificial intra-species and inter-species communication through synthetic circuits which incorporate components of bacterial QS systems. Engineered QS-based circuits have a wide range of applications such as production of biochemicals, tissue engineering, and mixed-species fermentations. They are also highly useful in designing microbial biosensors to identify bacterial species present in the environment and within living organisms. In this review, we first provide an overview of bacterial QS systems and the mechanisms developed by bacteria and higher organisms to obstruct QS communications. Next, we describe the different ways in which researchers have designed QS-based circuits and their applications in biotechnology. Finally, disruption of quorum sensing is discussed as a viable strategy for preventing the formation of harmful biofilms in membrane bioreactors and marine transportation.

  8. Bioactive proteins from Solanaceae as quorum sensing inhibitors against virulence in Pseudomonas aeruginosa.

    PubMed

    Singh, Gurpreet; Tamboli, Ekant; Acharya, Aurovind; Kumarasamy, Chellan; Mala, Kanchana; Raman, Pachaiappan

    2015-06-01

    Cell-to-cell communication or quorum sensing (QS) is a generic event in bacteria that is used to coordinate gene expression among local populations. The phenomenon of QS depends on the fact that presence of sufficient bacteria ascertains a threshold level of autoinducer concentration that allows bacteria to sense a critical cell mass and to activate or repress target genes. Thus, QS has been an attractive target for the development of anti-infective strategies that are not based on the use of antibiotics. Several anti-QS approaches have been demonstrated including natural products from plant-based secondary metabolites. However, the role of plant bioactive proteins as an anti-QS peptide is yet to be deciphered. Against a backdrop of ever-increasing antibiotic resistant pathogens, there is a strong need for development of alternative therapeutic strategies. Thus, our hypothesis is that bioactive proteins from the plant family Solanaceae are quorum quenching molecules that can be exploited to develop a therapeutic strategy against virulence. We presume that bioactive proteins will inactivate or inhibit or degrade QS signals from bacteria to prevent cell-to-cell communication and thus inhibit development of virulence in Pseudomonas aeruginosa. Further, the use of proteins as quorum quenchers will delay the bacteria to develop resistance against these quenching molecules.

  9. Exploiting Quorum Sensing Interfering Strategies in Gram-Negative Bacteria for the Enhancement of Environmental Applications

    PubMed Central

    Zhang, Weiwei; Li, Chenghua

    2016-01-01

    Quorum sensing (QS) is a widespread intercellular form of communication to coordinate physiological processes and cooperative activities of bacteria at the population level, and it depends on the production, secretion, and detection of small diffusible autoinducers, such as acyl-homoserine lactones (AHLs), auto-inducing oligo-peptides (AIPs) and autoinducer 2. In this review, the function of QS autoinducers of gram-negative bacteria in different aspects of wastewater treatment systems is examined. Based on research primarily performed over the past 10 years, QS involvement in the formation of biofilm and aerobic granules and changes of the microbial community and degradation/transformation pathways is discussed. In particular, the QS pathway in the role of bacterial infections and disease prevention in aquaculture is addressed. Interference of QS autoinducer-regulated pathways is considered potential treatment for a variety of environmentally related problems. This review is expected to serve as a stepping stone for further study and development strategies based on the mediation of QS-regulated pathways to enhance applications in both wastewater treatment systems and aquaculture. PMID:26779175

  10. Subtilosin Prevents Biofilm Formation by Inhibiting Bacterial Quorum Sensing.

    PubMed

    Algburi, Ammar; Zehm, Saskia; Netrebov, Victoria; Bren, Anzhelica B; Chistyakov, Vladimir; Chikindas, Michael L

    2017-03-01

    Subtilosin, the cyclic lantibiotic protein produced by Bacillus subtilis KATMIRA1933, targets the surface receptor and electrostatically binds to the bacterial cell membrane. In this study, subtilosin was purified using ammonium sulfate ((NH4)2SO4) precipitation and purified via column chromatography. Subtilosin's antibacterial minimum and sub-minimum inhibitory concentrations (MIC and sub-MIC) and anti-biofilm activity (biofilm prevention) were established. Subtilosin was evaluated as a quorum sensing (QS) inhibitor in Gram-positive bacteria using Fe(III) reduction assay. In Gram-negative bacteria, subtilosin was evaluated as a QS inhibitor utilizing Chromobacterium voilaceum as a microbial reporter. The results showed that Gardnerella vaginalis was more sensitive to subtilosin with MIC of 6.25 μg/mL when compared to Listeria monocytogenes (125 μg/mL). The lowest concentration of subtilosin, at which more than 90% of G. vaginalis biofilm was inhibited without effecting the growth of planktonic cells, was 0.78 μg/mL. About 80% of L. monocytogenes and more than 60% of Escherichia coli biofilm was inhibited when 15.1 μg/mL of subtilosin was applied. Subtilosin with 7.8-125 μg/mL showed a significant reduction in violacein production without any inhibitory effect on the growth of C. violaceum. Subtilosin at 3 and 4 μg/mL reduced the level of Autoinducer-2 (AI-2) production in G. vaginalis. However, subtilosin did not influence AI-2 production by L. monocytogenes at sub-MICs of 0.95-15.1 μg/mL. To our knowledge, this is the first report exploring the relationship between biofilm prevention and quorum sensing inhibition in G. vaginalis using subtilosin as a quorum sensing inhibitor.

  11. Adaptive Significance of Quorum Sensing-Dependent Regulation of Rhamnolipids by Integration of Growth Rate in Burkholderia glumae: A Trade-Off between Survival and Efficiency

    PubMed Central

    Nickzad, Arvin; Déziel, Eric

    2016-01-01

    Quorum sensing (QS) is a cell density-dependent mechanism which enables a population of bacteria to coordinate cooperative behaviors in response to the accumulation of self-produced autoinducer signals in their local environment. An emerging framework is that the adaptive significance of QS in the regulation of production of costly extracellular metabolites (“public goods”) is to maintain the homeostasis of cooperation. We investigated this model using the phytopathogenic bacterium Burkholderia glumae, which we have previously demonstrated uses QS to regulate the production of rhamnolipids, extracellular surface-active glycolipids promoting the social behavior called “swarming motility.” Using mass spectrometric quantification and chromosomal lux-based gene expression, we made the unexpected finding that when unrestricted nutrient resources are provided, production of rhamnolipids is carried out completely independently of QS regulation. This is a unique observation among known QS-controlled factors in bacteria. On the other hand, under nutrient-limited conditions, QS then becomes the main regulating mechanism, significantly enhancing the specific rhamnolipids yield. Accordingly, decreasing nutrient concentrations amplifies rhamnolipid biosynthesis gene expression, revealing a system where QS-dependent regulation is specifically triggered by the growth rate of the population, rather than by its cell density. Furthermore, a gradual increase in QS signal specific concentration upon decrease of specific growth rate suggests a reduction in quorum threshold, which reflects an increase in cellular demand for production of QS-dependent target gene product at low density populations. Integration of growth rate with QS as a decision-making mechanism for biosynthesis of costly metabolites, such as rhamnolipids, could serve to assess the demand and timing for expanding the carrying capacity of a population through spatial expansion mechanisms, such as swarming

  12. A crucial role for spatial distribution in bacterial quorum sensing

    PubMed Central

    Gao, Meng; Zheng, Huizhen; Ren, Ying; Lou, Ruyun; Wu, Fan; Yu, Weiting; Liu, Xiudong; Ma, Xiaojun

    2016-01-01

    Quorum sensing (QS) is a process that enables bacteria to communicate using secreted signaling molecules, and then makes a population of bacteria to regulate gene expression collectively and control behavior on a community-wide scale. Theoretical studies of efficiency sensing have suggested that both mass-transfer performance in the local environment and the spatial distribution of cells are key factors affecting QS. Here, an experimental model based on hydrogel microcapsules with a three-dimensional structure was established to investigate the influence of the spatial distribution of cells on bacterial QS. Vibrio harveyi cells formed different spatial distributions in the microcapsules, i.e., they formed cell aggregates with different structures and sizes. The cell aggregates displayed stronger QS than did unaggregated cells even when equal numbers of cells were present. Large aggregates (LA) of cells, with a size of approximately 25 μm, restricted many more autoinducers (AIs) than did small aggregates (SA), with a size of approximately 10 μm, thus demonstrating that aggregate size significantly affects QS. These findings provide a powerful demonstration of the fact that the spatial distribution of cells plays a crucial role in bacterial QS. PMID:27698391

  13. Quorum sensing triggers the stochastic escape of individual cells from Pseudomonas putida biofilms

    PubMed Central

    Cárcamo-Oyarce, Gerardo; Lumjiaktase, Putthapoom; Kümmerli, Rolf; Eberl, Leo

    2015-01-01

    The term ‘quorum sensing’ (QS) is generally used to describe the phenomenon that bacteria release and perceive signal molecules to coordinate cooperative behaviour in response to their population size. QS-based communication has therefore been considered a social trait. Here we show that QS signals (N-acyl-homoserine lactones, AHLs) are stochastically produced in young biofilms of Pseudomonas putida and act mainly as self-regulatory signals rather than inducing neighbouring cells. We demonstrate that QS induces the expression of putisolvin biosurfactants that are not public goods, thereby triggering asocial motility of induced cells out of microcolonies. Phenotypic heterogeneity is most prominent in the early stages of biofilm development, whereas at later stages behaviour patterns across cells become more synchronized. Our findings broaden our perspective on QS by showing that AHLs can control the expression of asocial (self-directed) traits, and that heterogeneity in QS can serve as a mechanism to drive phenotypic heterogeneity in self-directed behaviour. PMID:25592773

  14. Quorum Sensing Inhibitors from the Sea Discovered Using Bacterial N-acyl-homoserine Lactone-Based Biosensors.

    PubMed

    Saurav, Kumar; Costantino, Valeria; Venturi, Vittorio; Steindler, Laura

    2017-02-23

    Marine natural products with antibiotic activity have been a rich source of drug discovery; however, the emergence of antibiotic-resistant bacterial strains has turned attention towards the discovery of alternative innovative strategies to combat pathogens. In many pathogenic bacteria, the expression of virulence factors is under the regulation of quorum sensing (QS). QS inhibitors (QSIs) present a promising alternative or potential synergistic treatment since they disrupt the signaling pathway used for intra- and interspecies coordination of expression of virulence factors. This review covers the set of molecules showing QSI activity that were isolated from marine organisms, including plants (algae), animals (sponges, cnidarians, and bryozoans), and microorganisms (bacteria, fungi, and cyanobacteria). The compounds found and the methods used for their isolation are the emphasis of this review.

  15. Quorum Sensing Inhibitors from the Sea Discovered Using Bacterial N-acyl-homoserine Lactone-Based Biosensors

    PubMed Central

    Saurav, Kumar; Costantino, Valeria; Venturi, Vittorio; Steindler, Laura

    2017-01-01

    Marine natural products with antibiotic activity have been a rich source of drug discovery; however, the emergence of antibiotic-resistant bacterial strains has turned attention towards the discovery of alternative innovative strategies to combat pathogens. In many pathogenic bacteria, the expression of virulence factors is under the regulation of quorum sensing (QS). QS inhibitors (QSIs) present a promising alternative or potential synergistic treatment since they disrupt the signaling pathway used for intra- and interspecies coordination of expression of virulence factors. This review covers the set of molecules showing QSI activity that were isolated from marine organisms, including plants (algae), animals (sponges, cnidarians, and bryozoans), and microorganisms (bacteria, fungi, and cyanobacteria). The compounds found and the methods used for their isolation are the emphasis of this review. PMID:28241461

  16. Quorum-Sensing Systems LuxS/Autoinducer 2 and Com Regulate Streptococcus pneumoniae Biofilms in a Bioreactor with Living Cultures of Human Respiratory Cells

    PubMed Central

    Howery, Kristen E.; Ludewick, Herbert P.; Nava, Porfirio; Klugman, Keith P.

    2013-01-01

    Streptococcus pneumoniae forms organized biofilms in the human upper respiratory tract that may play an essential role in both persistence and acute respiratory infection. However, the production and regulation of biofilms on human cells is not yet fully understood. In this work, we developed a bioreactor with living cultures of human respiratory epithelial cells (HREC) and a continuous flow of nutrients, mimicking the microenvironment of the human respiratory epithelium, to study the production and regulation of S. pneumoniae biofilms (SPB). SPB were also produced under static conditions on immobilized HREC. Our experiments demonstrated that the biomass of SPB increased significantly when grown on HREC compared to the amount on abiotic surfaces. Additionally, pneumococcal strains produced more early biofilms on lung cells than on pharyngeal cells. Utilizing the bioreactor or immobilized human cells, the production of early SPB was found to be regulated by two quorum-sensing systems, Com and LuxS/AI-2, since a mutation in either comC or luxS rendered the pneumococcus unable to produce early biofilms on HREC. Interestingly, while LuxS/autoinducer 2 (AI-2) regulated biofilms on both HREC and abiotic surfaces, Com control was specific for those structures produced on HREC. The biofilm phenotypes of strain D39-derivative ΔcomC and ΔluxS QS mutants were reversed by genetic complementation. Of note, SPB formed on immobilized HREC and incubated under static conditions were completely lysed 24 h postinoculation. Biofilm lysis was also regulated by the Com and LuxS/AI-2 quorum-sensing systems. PMID:23403556

  17. Quorum-sensing systems LuxS/autoinducer 2 and Com regulate Streptococcus pneumoniae biofilms in a bioreactor with living cultures of human respiratory cells.

    PubMed

    Vidal, Jorge E; Howery, Kristen E; Ludewick, Herbert P; Nava, Porfirio; Klugman, Keith P

    2013-04-01

    Streptococcus pneumoniae forms organized biofilms in the human upper respiratory tract that may play an essential role in both persistence and acute respiratory infection. However, the production and regulation of biofilms on human cells is not yet fully understood. In this work, we developed a bioreactor with living cultures of human respiratory epithelial cells (HREC) and a continuous flow of nutrients, mimicking the microenvironment of the human respiratory epithelium, to study the production and regulation of S. pneumoniae biofilms (SPB). SPB were also produced under static conditions on immobilized HREC. Our experiments demonstrated that the biomass of SPB increased significantly when grown on HREC compared to the amount on abiotic surfaces. Additionally, pneumococcal strains produced more early biofilms on lung cells than on pharyngeal cells. Utilizing the bioreactor or immobilized human cells, the production of early SPB was found to be regulated by two quorum-sensing systems, Com and LuxS/AI-2, since a mutation in either comC or luxS rendered the pneumococcus unable to produce early biofilms on HREC. Interestingly, while LuxS/autoinducer 2 (AI-2) regulated biofilms on both HREC and abiotic surfaces, Com control was specific for those structures produced on HREC. The biofilm phenotypes of strain D39-derivative ΔcomC and ΔluxS QS mutants were reversed by genetic complementation. Of note, SPB formed on immobilized HREC and incubated under static conditions were completely lysed 24 h postinoculation. Biofilm lysis was also regulated by the Com and LuxS/AI-2 quorum-sensing systems.

  18. Thermoelectric, band structure, chemical bonding and dispersion of optical constants of new metal chalcogenides Ba4CuGa5Q12 (Q=S, Se)

    NASA Astrophysics Data System (ADS)

    Reshak, A. H.; Azam, Sikander

    2014-08-01

    The electronic structure and dispersion of optical constants of the Ba4CuGa5S12 and Ba4CuGa5Se12 compounds were calculated by the first-principles full-potential linearized augmented plane wave (FPLAPW) method. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel-Vosko GGA (EVGGA) to calculate the electronic structures, Fermi surface, thermoelectric, chemical bonding and dispersion of optical constants of these compounds. By investigating the influence of replacing S by Se, it has been found that the charge density around 'Ga' is greater in Ba4CuGa5Se12 than Ba4CuGa5S12. Fermi surface of Ba4CuGa5S12 consists of an electronic sheet only because there is no empty region while Ba4CuGa5Se12 contains both holes and electronic sheets because this compound contains both empty and shaded region. As we replace S by Se the heights of the peaks decreases as a results the reflectivity also decreases. It is noticed that the reflectivity is over 68% (60%) for Ba4CuGa5S12 (Ba4CuGa5Se12) compounds within the energy range studied. This implies that the material will serve as a good reflector. By replacing S by Se the figure of merit values increases from 0.97 to 1.0, which shows the good thermoelectric behavior of both compounds.

  19. Thermoelectric, band structure, chemical bonding and dispersion of optical constants of new metal chalcogenides Ba4CuGa5Q12 (Q=S, Se)

    NASA Astrophysics Data System (ADS)

    Azam, Sikander; Reshak, A. H.

    2014-08-01

    The electronic structure and dispersion of optical constants of the Ba4CuGa5S12 and Ba4CuGa5Se12 compounds were calculated by the first-principles full-potential linearized augmented plane wave (FPLAPW) method. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel-Vosko GGA (EVGGA) to calculate the electronic structures, Fermi surface, thermoelectric, chemical bonding and dispersion of optical constants of these compounds. By investigating the influence of replacing S by Se, it has been found that the charge density around ‘Ga’ is greater in Ba4CuGa5Se12 than Ba4CuGa5S12. Fermi surface of Ba4CuGa5S12 consists of an electronic sheet only because there is no empty region while Ba4CuGa5Se12 contains both holes and electronic sheets because this compound contains both empty and shaded region. As we replace S by Se the heights of the peaks decreases as a results the reflectivity also decreases. It is noticed that the reflectivity is over 68% (60%) for Ba4CuGa5S12 (Ba4CuGa5Se12) compounds within the energy range studied. This implies that the material will serve as a good reflector. By replacing S by Se the figure of merit values increases from 0.97 to 1.0, which shows the good thermoelectric behavior of both compounds.

  20. 8-Hydroxyquinoline Schiff-base compounds as antioxidants and modulators of copper-mediated Aβ peptide aggregation.

    PubMed

    Gomes, Luiza M F; Vieira, Rafael P; Jones, Michael R; Wang, Michael C P; Dyrager, Christine; Souza-Fagundes, Elaine M; Da Silva, Jeferson G; Storr, Tim; Beraldo, Heloisa

    2014-10-01

    One of the hallmarks of Alzheimer's disease (AD) in the brain are amyloid-β (Aβ) plaques, and metal ions such as copper(II) and zinc(II) have been shown to play a role in the aggregation and toxicity of the Aβ peptide, the major constituent of these extracellular aggregates. Metal binding agents can promote the disaggregation of Aβ plaques, and have shown promise as AD therapeutics. Herein, we describe the syntheses and characterization of an acetohydrazone (8-H2QH), a thiosemicarbazone (8-H2QT), and a semicarbazone (8-H2QS) derived from 8-hydroxyquinoline. The three compounds are shown to be neutral at pH7.4, and are potent antioxidants as measured by a Trolox Equivalent Antioxidant Capacity (TEAC) assay. The ligands form complexes with Cu(II), 8-H2QT in a 1:1 metal:ligand ratio, and 8-H2QH and 8-H2QS in a 1:2 metal:ligand ratio. A preliminary aggregation inhibition assay using the Aβ1-40 peptide showed that 8-H2QS and 8-H2QH inhibit peptide aggregation in the presence of Cu(II). Native gel electrophoresis/Western blot and TEM images were obtained to give a more detailed picture of the extent and pathways of Aβ aggregation using the more neurotoxic Aβ1-42 in the presence and absence of Cu(II), 8-H2QH, 8-H2QS and the drug candidate PBT2. An increase in the formation of oligomeric species is evident in the presence of Cu(II). However, in the presence of ligands and Cu(II), the results match those for the peptide alone, suggesting that the ligands function by sequestering Cu(II) and limiting oligomer formation in this assay.

  1. Inactivation of the Haemophilus ducreyi luxS gene affects the virulence of this pathogen in human subjects.

    PubMed

    Labandeira-Rey, Maria; Janowicz, Diane M; Blick, Robert J; Fortney, Kate R; Zwickl, Beth; Katz, Barry P; Spinola, Stanley M; Hansen, Eric J

    2009-08-01

    Haemophilus ducreyi 35000HP contains a homologue of the luxS gene, which encodes an enzyme that synthesizes autoinducer 2 (AI-2) in other gram-negative bacteria. H. ducreyi 35000HP produced AI-2 that functioned in a Vibrio harveyi-based reporter system. A H. ducreyi luxS mutant was constructed by insertional inactivation of the luxS gene and lost the ability to produce AI-2. Provision of the H. ducreyi luxS gene in trans partially restored AI-2 production by the mutant. The luxS mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule-formation rate in 5 volunteers was 93.3% (95% confidence interval, 81.7%-99.9%) at 15 parent sites and 60.0% (95% confidence interval, 48.3%-71.7%) at 15 mutant sites (1-tailed P < .001). Thus, the luxS mutant was partially attenuated for virulence. This is the first report of AI-2 production contributing to the pathogenesis of a genital ulcer disease.

  2. Morpho-dynamic quantification of flow-driven rill erosion parameters based on physical principles

    NASA Astrophysics Data System (ADS)

    Mahmoodabadi, Majid; Ghadiri, Hossein; Yu, Bofu; Rose, Calvin

    2014-06-01

    Application of soil erosion models requires accurate estimation of model parameters under different environmental conditions. The purpose of this study was to propose a new approach based on rill geometry to determine accurate values of the H, F and J parameters of the Hairsine-Rose model under infiltration conditions. H is the fractional area covered with deposited sediments; F is the fractional stream power effective in entrainment and re-entrainment; J is a measure of erodibility, i.e. the amount of energy required to remove a kilogram of the soil. Different stream powers ranging from 0.09 to 0.77 W m-2 were generated in preformed rills in three soils. Using rill morphology measurements and sediment feedback relationship, transport capacity (Tc) was determined under steady-state conditions and the detachment capacity (Dc) was derived at the upslope end of the flume. The results showed that sediment concentration at the transport limit depends on the slope gradient as well as the particle size distribution. The value of H was related to the ratio of Dc/Tc and decreased with increasing stream power. The result indicated that the ratio of Dc/Tc decreased with stream power, due to faster increase of Tc than of Dc with stream power. A good fitness (R2 = 0.94) relationship was found between the H values obtained by the ratio of qs/Tc versus the predicted values through the feedback relationship. Depending on soil type, the average F value varied between 0.123 and 0.174 and the average values of J for the soils varied between 0.038 and 0.231 J kg-1. The soil containing larger aggregates showed higher values of F and vise versa. At lower stream powers, F showed greater variability, and approached to a relatively stable value of 0.1 at stream powers higher than about 0.6 W m-2. The behavior of F was attributed to infiltration and the subsequent decrease of stream power and increases of settling velocity.

  3. The Quantified Self: Fundamental Disruption in Big Data Science and Biological Discovery.

    PubMed

    Swan, Melanie

    2013-06-01

    A key contemporary trend emerging in big data science is the quantified self (QS)-individuals engaged in the self-tracking of any kind of biological, physical, behavioral, or environmental information as n=1 individuals or in groups. There are opportunities for big data scientists to develop new models to support QS data collection, integration, and analysis, and also to lead in defining open-access database resources and privacy standards for how personal data is used. Next-generation QS applications could include tools for rendering QS data meaningful in behavior change, establishing baselines and variability in objective metrics, applying new kinds of pattern recognition techniques, and aggregating multiple self-tracking data streams from wearable electronics, biosensors, mobile phones, genomic data, and cloud-based services. The long-term vision of QS activity is that of a systemic monitoring approach where an individual's continuous personal information climate provides real-time performance optimization suggestions. There are some potential limitations related to QS activity-barriers to widespread adoption and a critique regarding scientific soundness-but these may be overcome. One interesting aspect of QS activity is that it is fundamentally a quantitative and qualitative phenomenon since it includes both the collection of objective metrics data and the subjective experience of the impact of these data. Some of this dynamic is being explored as the quantified self is becoming the qualified self in two new ways: by applying QS methods to the tracking of qualitative phenomena such as mood, and by understanding that QS data collection is just the first step in creating qualitative feedback loops for behavior change. In the long-term future, the quantified self may become additionally transformed into the extended exoself as data quantification and self-tracking enable the development of new sense capabilities that are not possible with ordinary senses. The

  4. A novel compound to maintain a healthy oral plaque ecology in vitro

    PubMed Central

    Janus, Marleen M.; Crielaard, Wim; Zaura, Egija; Keijser, Bart J.; Brandt, Bernd W.; Krom, Bastiaan P.

    2016-01-01

    Objective Dental caries is caused by prolonged episodes of low pH due to acid production by oral biofilms. Bacteria within such biofilms communicate via quorum sensing (QS). QS regulates several phenotypic biofilm parameters, such as biofilm formation and the production of virulence factors. In this study, we evaluated the effect of several QS modifiers on growth and the cariogenic potential of microcosm oral biofilms. Methods Biofilms were inoculated with pooled saliva and cultured in the presence of sucrose for 48 and 96 h. QS modifiers (or carrier controls) were continuously present. Lactic acid accumulation capacities were compared to evaluate the cariogenic potential of the biofilms. Subsequently, biofilm growth was quantified by determining colony forming unit counts (CFUs) and their ecology by 16S rDNA-based microbiome analyses. The minimal inhibitory concentration (MIC) for several Streptococcus spp. was determined using microbroth dilution. Results Of the tested QS modifiers only 3-oxo-N-(2-oxocyclohexyl)dodecanamide (3-Oxo-N) completely abolished lactic acid accumulation by the biofilms without affecting biofilm growth. This compound was selected for further investigation. The active range of 3-Oxo-N was 10–100 µM. The homologous QS molecule, acyl homoserine lactone C12, did not counteract the reduction in lactic acid accumulation, suggesting a mechanism other than QS inhibition. Microbial ecology analyses showed a reduction in the relative abundance of Streptococcus spp. in favor of the relative abundance of Veillonella spp. in the 3-Oxo-N exposed biofilms. The MIC of 3-Oxo-N for several streptococcal species varied between 8 and 32 µM. Conclusion 3-Oxo-N changes the ecological homeostasis of in vitro dental plaque. It reduces its cariogenic potential by minimizing lactic acid accumulation. Based on our in vitro data, 3-Oxo-N represents a promising compound in maintaining a healthy, non-cariogenic, ecology in in vivo dental plaque. PMID:27476444

  5. Quorum-sensing inhibitory compounds from extremophilic microorganisms isolated from a hypersaline cyanobacterial mat.

    PubMed

    Abed, Raeid M M; Dobretsov, Sergey; Al-Fori, Marwan; Gunasekera, Sarath P; Sudesh, Kumar; Paul, Valerie J

    2013-07-01

    In this study, extremely halophilic and moderately thermophilic microorganisms from a hypersaline microbial mat were screened for their ability to produce antibacterial, antidiatom, antialgal, and quorum-sensing (QS) inhibitory compounds. Five bacterial strains belonging to the genera Marinobacter and Halomonas and one archaeal strain belonging to the genus Haloterrigena were isolated from a microbial mat. The strains were able to grow at a maximum salinity of 22-25 % and a maximum temperature of 45-60 °C. Hexanes, dichloromethane, and butanol extracts from the strains inhibited the growth of at least one out of nine human pathogens. Only butanol extracts of supernatants of Halomonas sp. SK-1 inhibited growth of the microalga Dunaliella salina. Most extracts from isolates inhibited QS of the acyl homoserine lactone producer and reporter Chromobacterium violaceum CV017. Purification of QS inhibitory dichloromethane extracts of Marinobacter sp. SK-3 resulted in isolation of four related diketopiperazines (DKPs): cyclo(L-Pro-L-Phe), cyclo(L-Pro-L-Leu), cyclo(L-Pro-L-isoLeu), and cyclo(L-Pro-D-Phe). QS inhibitory properties of these DKPs were tested using C. violaceum CV017 and Escherichia coli-based QS reporters (pSB401 and pSB1075) deficient in AHL production. Cyclo(L-Pro-L-Phe) and cyclo(L-Pro-L-isoLeu) inhibited QS-dependent production of violacein by C. violaceum CV017. Cyclo(L-Pro-L-Phe), cyclo(L-Pro-L-Leu), and cyclo(L-Pro-L-isoLeu) reduced QS-dependent luminescence of the reporter E. coli pSB401 induced by 3-oxo-C6-HSL. Our study demonstrated the ability of halophilic and moderately thermophilic strains from a hypersaline microbial mat to produce biotechnologically relevant compounds that could be used as antifouling agents.

  6. Identification of catechin as one of the flavonoids from Combretum albiflorum bark extract that reduces the production of quorum-sensing-controlled virulence factors in Pseudomonas aeruginosa PAO1.

    PubMed

    Vandeputte, Olivier M; Kiendrebeogo, Martin; Rajaonson, Sanda; Diallo, Billo; Mol, Adeline; El Jaziri, Mondher; Baucher, Marie

    2010-01-01

    Quorum-sensing (QS) regulates the production of key virulence factors in Pseudomonas aeruginosa and other important pathogenic bacteria. In this report, extracts of leaves and bark of Combretum albiflorum (Tul.) Jongkind (Combretaceae) were found to quench the production of QS-dependent factors in P. aeruginosa PAO1. Chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. Purification and structural characterization of one of the active compounds led to the identification of the flavan-3-ol catechin [(2R,3S)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol]. The identity of catechin as one of the active molecules was confirmed by comparing the high-pressure liquid chromatography profiles and the mass spectrometry spectra obtained for a catechin standard and for the active C. albiflorum fraction. Moreover, standard catechin had a significant negative effect on pyocyanin and elastase productions and biofilm formation, as well as on the expression of the QS-regulated genes lasB and rhlA and of the key QS regulatory genes lasI, lasR, rhlI, and rhlR. The use of RhlR- and LasR-based biosensors indicated that catechin might interfere with the perception of the QS signal N-butanoyl-l-homoserine lactone by RhlR, thereby leading to a reduction of the production of QS factors. Hence, catechin, along with other flavonoids produced by higher plants, might constitute a first line of defense against pathogenic attacks by affecting QS mechanisms and thereby virulence factor production.

  7. Identification of Catechin as One of the Flavonoids from Combretum albiflorum Bark Extract That Reduces the Production of Quorum-Sensing-Controlled Virulence Factors in Pseudomonas aeruginosa PAO1 ▿

    PubMed Central

    Vandeputte, Olivier M.; Kiendrebeogo, Martin; Rajaonson, Sanda; Diallo, Billo; Mol, Adeline; El Jaziri, Mondher; Baucher, Marie

    2010-01-01

    Quorum-sensing (QS) regulates the production of key virulence factors in Pseudomonas aeruginosa and other important pathogenic bacteria. In this report, extracts of leaves and bark of Combretum albiflorum (Tul.) Jongkind (Combretaceae) were found to quench the production of QS-dependent factors in P. aeruginosa PAO1. Chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. Purification and structural characterization of one of the active compounds led to the identification of the flavan-3-ol catechin [(2R,3S)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol]. The identity of catechin as one of the active molecules was confirmed by comparing the high-pressure liquid chromatography profiles and the mass spectrometry spectra obtained for a catechin standard and for the active C. albiflorum fraction. Moreover, standard catechin had a significant negative effect on pyocyanin and elastase productions and biofilm formation, as well as on the expression of the QS-regulated genes lasB and rhlA and of the key QS regulatory genes lasI, lasR, rhlI, and rhlR. The use of RhlR- and LasR-based biosensors indicated that catechin might interfere with the perception of the QS signal N-butanoyl-l-homoserine lactone by RhlR, thereby leading to a reduction of the production of QS factors. Hence, catechin, along with other flavonoids produced by higher plants, might constitute a first line of defense against pathogenic attacks by affecting QS mechanisms and thereby virulence factor production. PMID:19854927

  8. Chemical Inhibition of Kynureninase Reduces Pseudomonas aeruginosa Quorum Sensing and Virulence Factor Expression.

    PubMed

    Kasper, Stephen H; Bonocora, Richard P; Wade, Joseph T; Musah, Rabi Ann; Cady, Nathaniel C

    2016-04-15

    The opportunistic pathogen Pseudomonas aeruginosa utilizes multiple quorum sensing (QS) pathways to coordinate an arsenal of virulence factors. We previously identified several cysteine-based compounds inspired by natural products from the plant Petiveria alliacea which are capable of antagonizing multiple QS circuits as well as reducing P. aeruginosa biofilm formation. To understand the global effects of such compounds on virulence factor production and elucidate their mechanism of action, RNA-seq transcriptomic analysis was performed on P. aeruginosa PAO1 exposed to S-phenyl-l-cysteine sulfoxide, the most potent inhibitor from the prior study. Exposure to this inhibitor down-regulated expression of several QS-regulated virulence operons (e.g., phenazine biosynthesis, type VI secretion systems). Interestingly, many genes that were differentially regulated pertain to the related metabolic pathways that yield precursors of pyochelin, tricarboxylic acid cycle intermediates, phenazines, and Pseudomonas quinolone signal (PQS). Activation of the MexT-regulon was also indicated, including the multidrug efflux pump encoded by mexEF-oprN, which has previously been shown to inhibit QS and pathogenicity. Deeper investigation of the metabolites involved in these systems revealed that S-phenyl-l-cysteine sulfoxide has structural similarity to kynurenine, a precursor of anthranilate, which is critical for P. aeruginosa virulence. By supplementing exogenous anthranilate, the QS-inhibitory effect was reversed. Finally, it was shown that S-phenyl-l-cysteine sulfoxide competitively inhibits P. aeruginosa kynureninase (KynU) activity in vitro and reduces PQS production in vivo. The kynurenine pathway has been implicated in P. aeruginosa QS and virulence factor expression; however, this is the first study to show that targeted inhibition of KynU affects P. aeruginosa gene expression and QS, suggesting a potential antivirulence strategy.

  9. Antibacterial and Anti-Quorum Sensing Molecular Composition Derived from Quercus cortex (Oak bark) Extract.

    PubMed

    Deryabin, Dmitry G; Tolmacheva, Anna A

    2015-09-17

    Quercus cortex (Oak bark) has been used in European folk medicine since medieval times for treatment of diarrhea, stomatitis, pharyngitis and skin inflammations. Its antimicrobial activity is a well-known therapeutic property of oak bark, and its novel anti-quorum sensing (QS) ability has also been described recently. In this study, we examined the bioactive compounds of Quercus cortex extract and compared their direct antibacterial and regulatory anti-QS effects against Chromobacterium violaceum CV026 in a biotest. Evaluation of the original Quercus cortex extract showed weak antibacterial and prominent anti-QS activities that were retained and completely restored when the samples were dried and re-hydrated. The one-step liquid chromatography result indicated that the anti-QS activity might be determined by hydrophobic compounds; however, the subsequent reverse phase high performance liquid chromatography led to dissipation and loss of the activity. The gas chromatography-mass spectrometry gave excellent resolution between a majority of the compounds. Based on this result, 10 of the 35 identified small molecules were selected for further screening. The subsequent investigation indicated several compounds determined both the antibacterial and anti-QS activities of the Quercus cortex extract. Direct antibacterial activity was shown for 1,2,3-benzenetriol and 4-propyl-1,3-benzenediol, while sub-inhibitory concentrations of these compounds led to anti-QS effects. Five compounds: 4-(3-hydroxy-1-propenyl)-2-methoxy-phenol; 3,4,5-trimethoxyphenol; 4-hydroxy-3-methoxybenzaldehyde; 7-hydroxy-6-methoxy-2H-1-benzopyran-2-one and 2H-1-benzopyran-2-one were characterized as QS inhibitors independent of any effect on bacterial growth. Biologically relevant concentrations of each single component showed weak activity only while reconstruction of the small molecule composition derived from the Quercus cortex extract provided comparable complementary activity against C. violaceum

  10. Non-antibiotic quorum sensing inhibitors acting against N-acyl homoserine lactone synthase as druggable target

    PubMed Central

    Chang, Chien-Yi; Krishnan, Thiba; Wang, Hao; Chen, Ye; Yin, Wai-Fong; Chong, Yee-Meng; Tan, Li Ying; Chong, Teik Min; Chan, Kok-Gan

    2014-01-01

    N-acylhomoserine lactone (AHL)-based quorum sensing (QS) is important for the regulation of proteobacterial virulence determinants. Thus, the inhibition of AHL synthases offers non-antibiotics-based therapeutic potentials against QS-mediated bacterial infections. In this work, functional AHL synthases of Pseudomonas aeruginosa LasI and RhlI were heterologously expressed in an AHL-negative Escherichia coli followed by assessments on their AHLs production using AHL biosensors and high resolution liquid chromatography–mass spectrometry (LCMS). These AHL-producing E. coli served as tools for screening AHL synthase inhibitors. Based on a campaign of screening synthetic molecules and natural products using our approach, three strongest inhibitors namely are salicylic acid, tannic acid and trans-cinnamaldehyde have been identified. LCMS analysis further confirmed tannic acid and trans-cinnemaldehyde efficiently inhibited AHL production by RhlI. We further demonstrated the application of trans-cinnemaldehyde inhibiting Rhl QS system regulated pyocyanin production in P. aeruginosa up to 42.06%. Molecular docking analysis suggested that trans-cinnemaldehyde binds to the LasI and EsaI with known structures mainly interacting with their substrate binding sites. Our data suggested a new class of QS-inhibiting agents from natural products targeting AHL synthase and provided a potential approach for facilitating the discovery of anti-QS signal synthesis as basis of novel anti-infective approach. PMID:25430794

  11. N-Acetylglucosamine Inhibits LuxR, LasR and CviR Based Quorum Sensing Regulated Gene Expression Levels

    PubMed Central

    Kimyon, Önder; Ulutürk, Zehra İ.; Nizalapur, Shashidhar; Lee, Matthew; Kutty, Samuel K.; Beckmann, Sabrina; Kumar, Naresh; Manefield, Mike

    2016-01-01

    N-acetyl glucosamine, the monomer of chitin, is an abundant source of carbon and nitrogen in nature as it is the main component and breakdown product of many structural polymers. Some bacteria use N-acyl-L-homoserine lactone (AHL) mediated quorum sensing (QS) to regulate chitinase production in order to catalyze the cleavage of chitin polymers into water soluble N-acetyl-D-glucosamine (NAG) monomers. In this study, the impact of NAG on QS activities of LuxR, LasR, and CviR regulated gene expression was investigated by examining the effect of NAG on QS regulated green fluorescent protein (GFP), violacein and extracellular chitinase expression. It was discovered that NAG inhibits AHL dependent gene transcription in AHL reporter strains within the range of 50–80% reduction at low millimolar concentrations (0.25–5 mM). Evidence is presented supporting a role for both competitive inhibition at the AHL binding site of LuxR type transcriptional regulators and catabolite repression. Further, this study shows that NAG down-regulates CviR induced violacein production while simultaneously up-regulating CviR dependent extracellular enzymes, suggesting that an unknown NAG dependent regulatory component influences phenotype expression. The quorum sensing inhibiting activity of NAG also adds to the list of compounds with known quorum sensing inhibiting activities. PMID:27602027

  12. In Silico Evaluation of the Impacts of Quorum Sensing Inhibition (QSI) on Strain Competition and Development of QSI Resistance

    PubMed Central

    Wei, Guopeng; Lo, Chieh; Walsh, Connor; Hiller, N. Luisa; Marculescu, Radu

    2016-01-01

    As understanding of bacterial regulatory systems and pathogenesis continues to increase, QSI has been a major focus of research. However, recent studies have shown that mechanisms of resistance to quorum sensing (QS) inhibitors (QSIs) exist, calling into question their clinical value. We propose a computational framework that considers bacteria genotypes relative to QS genes and QS-regulated products including private, quasi-public, and public goods according to their impacts on bacterial fitness. Our results show (1) QSI resistance spreads when QS positively regulates the expression of private or quasi-public goods. (2) Resistance to drugs targeting secreted compounds downstream of QS for a mix of private, public, and quasi-public goods also spreads. (3) Changing the micro-environment during treatment with QSIs may decrease the spread of resistance. At fundamental-level, our simulation framework allows us to directly quantify cell-cell interactions and biofilm dynamics. Practically, the model provides a valuable tool for the study of QSI-based therapies, and the simulations reveal experimental paths that may guide QSI-based therapies in a manner that avoids or decreases the spread of QSI resistance. PMID:27734907

  13. In Silico Evaluation of the Impacts of Quorum Sensing Inhibition (QSI) on Strain Competition and Development of QSI Resistance

    NASA Astrophysics Data System (ADS)

    Wei, Guopeng; Lo, Chieh; Walsh, Connor; Hiller, N. Luisa; Marculescu, Radu

    2016-10-01

    As understanding of bacterial regulatory systems and pathogenesis continues to increase, QSI has been a major focus of research. However, recent studies have shown that mechanisms of resistance to quorum sensing (QS) inhibitors (QSIs) exist, calling into question their clinical value. We propose a computational framework that considers bacteria genotypes relative to QS genes and QS-regulated products including private, quasi-public, and public goods according to their impacts on bacterial fitness. Our results show (1) QSI resistance spreads when QS positively regulates the expression of private or quasi-public goods. (2) Resistance to drugs targeting secreted compounds downstream of QS for a mix of private, public, and quasi-public goods also spreads. (3) Changing the micro-environment during treatment with QSIs may decrease the spread of resistance. At fundamental-level, our simulation framework allows us to directly quantify cell-cell interactions and biofilm dynamics. Practically, the model provides a valuable tool for the study of QSI-based therapies, and the simulations reveal experimental paths that may guide QSI-based therapies in a manner that avoids or decreases the spread of QSI resistance.

  14. Synthetic Quorum Sensing and Cell-Cell Communication in Gram-Positive Bacillus megaterium.

    PubMed

    Marchand, Nicholas; Collins, Cynthia H

    2016-07-15

    The components of natural quorum-sensing (QS) systems can be used to engineer synthetic communication systems that regulate gene expression in response to chemical signals. We have used the machinery from the peptide-based agr QS system from Staphylococcus aureus to engineer a synthetic QS system in Bacillus megaterium to enable autoinduction of a target gene at high cell densities. Growth and gene expression from these synthetic QS cells were characterized in both complex and minimal media. We also split the signal production and sensing components between two strains of B. megaterium to produce sender and receiver cells and characterized the resulting communication in liquid media and on semisolid agar. The system described in this work represents the first synthetic QS and cell-cell communication system that has been engineered to function in a Gram-positive host, and it has the potential to enable the generation of dynamic gene regulatory networks in B. megaterium and other Gram-positive organisms.

  15. Scaffold of Selenium Nanovectors and Honey Phytochemicals for Inhibition of Pseudomonas aeruginosa Quorum Sensing and Biofilm Formation

    PubMed Central

    Prateeksha; Singh, Braj R.; Shoeb, M.; Sharma, S.; Naqvi, A. H.; Gupta, Vijai K.; Singh, Brahma N.

    2017-01-01

    Honey is an excellent source of polyphenolic compounds that are effective in attenuating quorum sensing (QS), a chemical process of cell-to-cell communication system used by the opportunistic pathogen Pseudomonas aeruginosa to regulate virulence and biofilm formation. However, lower water solubility and inadequate bioavailability remains major concerns of these therapeutic polyphenols. Its therapeutic index can be improved by using nano-carrier systems to target QS signaling potently. In the present study, we fabricated a unique drug delivery system comprising selenium nanoparticles (SeNPs; non-viral vectors) and polyphenols of honey (HP) for enhancement of anti-QS activity of HP against P. aeruginosa PAO1. The developed selenium nano-scaffold showed superior anti-QS activity, anti-biofilm efficacy, and anti-virulence potential in both in-vitro and in-vivo over its individual components, SeNPs and HP. LasR is inhibited by selenium nano-scaffold in-vitro. Using computational molecular docking studies, we have also demonstrated that the anti-virulence activity of selenium nano-scaffold is reliant on molecular binding that occurs between HP and the QS receptor LasR through hydrogen bonding and hydrophobic interactions. Our preliminary investigations with selenium-based nano-carriers hold significant promise to improve anti-virulence effectiveness of phytochemicals by enhancing effective intracellular delivery. PMID:28386534

  16. Functional amyloids keep quorum-sensing molecules in check.

    PubMed

    Seviour, Thomas; Hansen, Susan Hove; Yang, Liang; Yau, Yin Hoe; Wang, Victor Bochuan; Stenvang, Marcel R; Christiansen, Gunna; Marsili, Enrico; Givskov, Michael; Chen, Yicai; Otzen, Daniel E; Nielsen, Per Halkjær; Geifman-Shochat, Susana; Kjelleberg, Staffan; Dueholm, Morten S

    2015-03-06

    The mechanism by which extracellular metabolites, including redox mediators and quorum-sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum-sensing (QS) molecules, 2-heptyl-3-hydroxy-4(1H)-quinolone and N-(3-oxododecanoyl)-l-homoserine lactone, and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signal-amyloid interactions, but specific interactions also play a role. Transient interactions allow for rapid association and dissociation kinetics, which make the QS molecules bioavailable and at the same time secure within the extracellular matrix as a consequence of serial bindings. Retention of the QS molecules was confirmed using Pseudomonas aeruginosa PAO1-based 2-heptyl-3-hydroxy-4(1H)-quinolone and N-(3-oxododecanoyl)-l-homoserine lactone reporter assays, showing that Fap fibrils pretreated with the QS molecules activate the reporters even after sequential washes. Pyocyanin retention was validated by electrochemical analysis of pyocyanin-pretreated Fap fibrils subjected to the same washing process. Results suggest that QS molecule-amyloid interactions are probably important in the turbulent environments commonly encountered in natural habitats.

  17. Quorum Sensing Inhibition and Structure-Activity Relationships of β-Keto Esters.

    PubMed

    Forschner-Dancause, Stephanie; Poulin, Emily; Meschwitz, Susan

    2016-07-25

    Traditional therapeutics to treat bacterial infections have given rise to multi-drug resistant pathogens, which pose a major threat to human and animal health. In several pathogens, quorum sensing (QS)-a cell-cell communication system in bacteria-controls the expression of genes responsible for pathogenesis, thus representing a novel target in the fight against bacterial infections. Based on the structure of the autoinducers responsible for QS activity and other QS inhibitors, we hypothesize that β-keto esters with aryl functionality could possess anti-QS activity. A panel of nineteen β-keto ester analogs was tested for the inhibition of bioluminescence (a QS-controlled phenotype) in the marine pathogen Vibrio harveyi. Initial screening demonstrated the need of a phenyl ring at the C-3 position for antagonistic activity. Further additions to the phenyl ring with 4-substituted halo groups or a 3- or 4-substituted methoxy group resulted in the most active compounds with IC50 values ranging from 23 µM to 53 µM. The compounds additionally inhibit green fluorescent protein production by E. coli JB525. Evidence is presented that aryl β-keto esters may act as antagonists of bacterial quorum sensing by competing with N-acyl homoserine lactones for receptor binding. Expansion of the β-keto ester panel will enable us to obtain more insight into the structure-activity relationships needed to allow for the development of novel anti-virulence agents.

  18. Functional Amyloids Keep Quorum-sensing Molecules in Check*

    PubMed Central

    Seviour, Thomas; Hansen, Susan Hove; Yang, Liang; Yau, Yin Hoe; Wang, Victor Bochuan; Stenvang, Marcel R.; Christiansen, Gunna; Marsili, Enrico; Givskov, Michael; Chen, Yicai; Otzen, Daniel E.; Nielsen, Per Halkjær; Geifman-Shochat, Susana; Kjelleberg, Staffan; Dueholm, Morten S.

    2015-01-01

    The mechanism by which extracellular metabolites, including redox mediators and quorum-sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum-sensing (QS) molecules, 2-heptyl-3-hydroxy-4(1H)-quinolone and N-(3-oxododecanoyl)-l-homoserine lactone, and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signal-amyloid interactions, but specific interactions also play a role. Transient interactions allow for rapid association and dissociation kinetics, which make the QS molecules bioavailable and at the same time secure within the extracellular matrix as a consequence of serial bindings. Retention of the QS molecules was confirmed using Pseudomonas aeruginosa PAO1-based 2-heptyl-3-hydroxy-4(1H)-quinolone and N-(3-oxododecanoyl)-l-homoserine lactone reporter assays, showing that Fap fibrils pretreated with the QS molecules activate the reporters even after sequential washes. Pyocyanin retention was validated by electrochemical analysis of pyocyanin-pretreated Fap fibrils subjected to the same washing process. Results suggest that QS molecule-amyloid interactions are probably important in the turbulent environments commonly encountered in natural habitats. PMID:25586180

  19. Interfering with Bacterial Quorum Sensing

    PubMed Central

    Reuter, Kerstin; Steinbach, Anke; Helms, Volkhard

    2016-01-01

    Quorum sensing (QS) describes the exchange of chemical signals in bacterial populations to adjust the bacterial phenotypes according to the density of bacterial cells. This serves to express phenotypes that are advantageous for the group and ensure bacterial survival. To do so, bacterial cells synthesize autoinducer (AI) molecules, release them to the environment, and take them up. Thereby, the AI concentration reflects the cell density. When the AI concentration exceeds a critical threshold in the cells, the AI may activate the expression of virulence-associated genes or of luminescent proteins. It has been argued that targeting the QS system puts less selective pressure on these pathogens and should avoid the development of resistant bacteria. Therefore, the molecular components of QS systems have been suggested as promising targets for developing new anti-infective compounds. Here, we review the QS systems of selected gram-negative and gram-positive bacteria, namely, Vibrio fischeri, Pseudomonas aeruginosa, and Staphylococcus aureus, and discuss various antivirulence strategies based on blocking different components of the QS machinery. PMID:26819549

  20. Simulation of the Dynamics of Bacterial Quorum Sensing.

    PubMed

    Psarras, Anastasios; Karafyllidis, Ioannis

    2015-01-13

    Quorum sensing (QS) is a signaling mechanism that pathogenic bacteria use to communicate and synchronize the production of exofactors to attack their hosts. Understanding and controlling QS is an important step towards a possible solution to the growing problem of antibiotic resistance. QS is a cooperative effort of a bacterial population in which some of the bacteria do not participate. This phenomenon is usually studied using game theory and the non-participating bacteria are modeled as cheaters that exploit the production of common goods (exofactors) by other bacteria. Here, we take a different approach to study the QS dynamics of a growing bacterial population. We model the bacterial population as a growing graph and use spectral graph theory to compute the evolution of its synchronizability. We also treat each bacterium as a source of signaling molecules and use the diffusion equation to compute the signaling molecule distribution. We formulate a cost function based on Lagrangian dynamics that combines the time-like synchronization with the space-like diffusion of signaling molecules. Our results show that the presence of non-participating bacteria improves the homogeneity of the signaling molecule distribution preventing thus an early onset of exofactor production and has a positive effect on the optimization of QS signaling and on attack synchronization.

  1. Electrochemical spectroscopic investigations on the interaction of an ytterbium complex with DNA and their analytical applications such as biosensor.

    PubMed

    Ilkhani, Hoda; Ganjali, Mohamad Reza; Arvand, Majid; Hejazi, Mohammad Saeid; Azimi, Fateme; Norouzi, Parviz

    2011-12-01

    Metal ion-DNA interactions are important in nature, often changing the genetic material's structure and function. A new Yb complex of YbCl(3) (tris(8-hydroxyquinoline-5-sulfonic acid) ytterbium) was synthesized and utilized as an electrochemical indicator for the detection of DNA oligonucleotide based on its interaction with Yb(QS)(3). Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of Yb(QS)(3) with ds-DNA. It was revealed that Yb(QS)(3) presented an excellent electrochemical activity on glassy carbon electrode (GCE) and could intercalate into the double helix of double-stranded DNA (ds-DNA). The binding mechanism of interaction was elucidated on glassy carbon electrode dipped in DNA solution and DNA modified carbon paste electrode by using differential pulse voltammetry and cyclic voltammetry. The binding ratio between this complex and ds-DNA was calculated to be 1:1. The extent of hybridization was evaluated on the basis of the difference between signals of Yb(QS)(3) with probe DNA before and after hybridization with complementary DNA. With this approach, this DNA could be quantified over the range from 1 × 10(-8) to 1.1 × 10(-7)M. The interaction mode between Yb(QS)(3) and DNA was found to be mainly intercalative interaction. These results were confirmed with fluorescence experiments.

  2. Comparison of a parallel installation of laser and quartz tube strainmeters at the Geodynamic Observatory Moxa in Thuringia, Germany

    NASA Astrophysics Data System (ADS)

    Kobe, Martin; Jahr, Thomas; Kukowski, Nina; Methe, Pascal; Goepel, Andreas

    2015-04-01

    High-resolution continuous deformation measurements provide an important data base for studies on deformation of the solid Earth (e.g. due to tides or hydrologically-induced deformation) that has strain amplitudes from μm to nm. Time series can be obtained by different strainmeters that measure relative changes in length between two fixed points on the Earth's surface with a resolution up to 10-10 m. In order to improve the signal-to-noise ratio strainmeters are installed in galleries or caves with a thick mountain overburden. The Geodynamic Observatory Moxa operates beside seismological and gravimetrical sensor systems an extensive strainmeter array. It consists of a borehole extensometer, two quartz tubes at right angles and one diagonally-installed laser strainmeter. In 2011, two new laser strainmeters were added in cooperation with the company SIOS/Ilmenau. They are installed parallel to the quartz tubes and fixed to the bedrock by the same pylon. This kind of parallel installation is unique in the world and allows the direct comparison of measurements of horizontal length changes with different types of strainmeters for the first time. For the comparison of the data we used mainly the tidal analysis of three-years long time series, as well as the signal from a research borehole on the observatory's perimeter. The first results show a decrease of the long lasting device-specific drift by a factor of 2.3 - 2.5 × 10 of the laser strainmeters (LS) with respect to the quartz systems (QS). Furthermore, the signal-to-noise ratio of the LS is significantly higher than for the QS, as can be seen, for example, in the tidal amplitude factors (AF). In the north-south direction we determined AF ˜ 1.0 (LS) and AF ˜ 0.6 (QS) that yields LS- QS ˜ 1.66. In the east-west direction we found AF ˜ 0.67 (LS), AF ˜ 0.16 (QS), and therefore -LS QS ˜ 4.3. The tidal parameters are used to evaluate the new laser strainmeter system. Furthermore the determination of LS- QS

  3. Inhibition of marine biofouling by bacterial quorum sensing inhibitors

    PubMed Central

    Dobretsov, Sergey; Teplitski, Max; Bayer, Mirko; Gunasekera, Sarath; Proksch, Peter; Paul, Valerie J

    2012-01-01

    Seventy eight natural products from chemical libraries containing compounds from marine organisms (sponges, algae, fungi, tunicates and cyanobacteria) and terrestrial plants, were screened for the inhibition of bacterial quorum sensing (QS) using a reporter strain Chromobacterium violaceum CV017. About half of the natural products did not show any QS inhibition. Twenty four percent of the tested compounds inhibited QS of the reporter without causing toxicity. The QS inhibitory activities of the most potent and abundant compounds were further investigated using the LuxR-based reporter E. coli pSB401 and the LasR-based reporter E. coli pSB1075. Midpacamide and tenuazonic acid were toxic to the tested reporters. QS-dependent luminescence of the LasR-based reporter, which is normally induced by N-3-oxo-dodecanoyl-L-homoserine lactone, was reduced by demethoxy encecalin and hymenialdisin at concentrations 46.6 μM and 15μM, respectively. Hymenialdisin, demethoxy encecalin, microcolins A and B and kojic acid inhibited responses of the LuxR-based reporter induced by N-3-oxo-hexanoyl-L-homoserine lactone at concentrations 40.2 μM, 2.2 μM, 1.5 μM, 15 μM and 36 μM, respectively. The ability to prevent microfouling by one of the compounds screened in this study (kojic acid; final concentrations 330 μM and 1 mM) was tested in a controlled mesocosm experiment. Kojic acid inhibited formation of microbial communities on glass slides, decreasing the densities of bacteria and diatoms in comparison with the control lacking kojic acid. The study suggests that natural products with QS inhibitory properties can be used for controlling biofouling communities. PMID:21882898

  4. Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B.; Epp, Larry W.; Bagge, Leif

    2011-01-01

    High Q resonators are a critical component of stable, low-noise communication systems, radar, and precise timing applications such as atomic clocks. In electronic resonators based on Si integrated circuits, resistive losses increase as a result of the continued reduction in device dimensions, which decreases their Q values. On the other hand, due to the mechanical construct of bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators, such loss mechanisms are absent, enabling higher Q-values for both BAW and SAW resonators compared to their electronic counterparts. The other advantages of mechanical resonators are their inherently higher radiation tolerance, a factor that makes them attractive for NASA s extreme environment planetary missions, for example to the Jovian environments where the radiation doses are at hostile levels. Despite these advantages, both BAW and SAW resonators suffer from low resonant frequencies and they are also physically large, which precludes their integration into miniaturized electronic systems. Because there is a need to move the resonant frequency of oscillators to the order of gigahertz, new technologies and materials are being investigated that will make performance at those frequencies attainable. By moving to nanoscale structures, in this case vertically oriented, cantilevered carbon nanotubes (CNTs), that have larger aspect ratios (length/thickness) and extremely high elastic moduli, it is possible to overcome the two disadvantages of both bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators. Nano-electro-mechanical systems (NEMS) that utilize high aspect ratio nanomaterials exhibiting high elastic moduli (e.g., carbon-based nanomaterials) benefit from high Qs, operate at high frequency, and have small force constants that translate to high responsivity that results in improved sensitivity, lower power consumption, and im - proved tunablity. NEMS resonators have recently been demonstrated using topdown

  5. Quorum quenching activity of Syzygium cumini (L.) Skeels and its anthocyanin malvidin against Klebsiella pneumoniae.

    PubMed

    Gopu, Venkadesaperumal; Kothandapani, Sundar; Shetty, Prathapkumar Halady

    2015-02-01

    Many bacterial species use their intercellular signaling mechanism called quorum sensing (QS), which is found to be implicated in various factors including bacterial pathogenicity and food spoilage. Interrupting the bacterial communication is an attractive strategy to develop novel QS-based antibacterial drugs. Present study is aimed to investigate the quorum sensing inhibitory activity of Syzygium cumini and its anti-biofilm property against opportunistic pathogen using a biosensor strain Chromobacterium violaceum CV026. Ethanol extract of S. cumini was investigated for its anti-QS activity, and the possible active component was identified by docking with LasR receptor protein. Based on docking analysis, methanol extract was enriched for its total anthocyanin (STA) and its effect on QS regulated phenotypes was assessed. STA specifically inhibited the violacein production in C. violaceum; biofilm formation and EPS production in Klebsiella pneumoniae up to 82, 79.94 and 64.29% respectively. Synergistic activity of conventional antibiotics with STA enhanced the susceptibility of K. pneumoniae up to 58.45%. Molecular docking analysis of active components attributes the QSI activity of S. cumini to malvidin. Malvidin exhibited highest ligand binding with LasR receptor protein with docking score more than -7. Effect of malvidin to interrupt the QS regulated phenotypes was also assessed, and it was found to reduce the violacein production, biofilm formation and EPS production of K. pneumoniae in a concentration-dependent manner. These findings suggest that S. cumini can be used as novel QS-based antibacterial/anti-biofilm agent to manage food-borne pathogens and to increase food safety.

  6. A Strategy for Interpretation of Microearthquake Tomography Results in the Salton Sea Geothermal Field Based upon Rock Physics Interpretations of State 2-14 Borehole Logs

    SciTech Connect

    Bonner, B; Hutchings, L; Kasameyer, P

    2006-06-14

    We devise a strategy for analysis of Vp and Vs microearthquake tomography results in the Salton Sea geothermal field to identify important features of the geothermal reservoir. We first interpret rock properties in State 2-14 borehole based upon logged core through the reservoir. Then, we interpret seismic recordings in the well (Daley et al., 1988) to develop the strategy. We hypothesize that mapping Poisson's ratio has two applications for the Salton Sea geothermal reservoir: (1) to map the top of the reservoir, and (2) as a diagnostic for permeable zones. Poisson's ratio can be obtained from Vp and Vs. In the State 2-14 borehole, Poisson's ratio calculated from large scale averages ({approx} 150 m) shows a monotonic decrease with depth to about 1300 m, at which point it increases with depth. Our model is that the monotonic decrease is due to compaction, and the increase below 1300 m is due to the rocks being hydrothermally altered. We hypothesize we can map the depth to alteration by identifying the transition from decreasing to increasing values; and thus, map the top of the reservoir, which is associated with a known increase in sulfite, chlorite, and epidote alteration that may be indicative of hydrothermal activity. We also observe (from Daley et. al. plots) an anomalous drop in Poisson's ratio at a depth of about 900 m, within a sandstone formation. The sandstone has a P-wave velocity significantly higher than the siltstone above it but a lower velocity in the lower half of the formation relative to the upper half. We interpret the relative decrease in velocity to be due to fracturing and chemical alteration caused by permeability. We conclude that using Vp and Vs tomography results to obtain images of Poisson's ratio has the potential to identify significant features in the geothermal reservoir in this geologic setting. Seismic attenuation tomography results (mapped as Qp and Qs) should also be useful for evaluating geothermal reservoirs, but that is not

  7. Metabolomics analysis of fungal biofilm development and of arachidonic acid-based quorum sensing mechanism.

    PubMed

    Ząbek, Adam; Junka, Adam; Szymczyk, Patrycja; Wojtowicz, Wojciech; Klimek-Ochab, Magdalena; Młynarz, Piotr

    2017-04-03

    The infections caused by filamentous fungi are becoming worldwide problem of healthcare systems due to increasing drug-resistance of this microorganism and increasing number of immunocompromised nosocomial patients. These infections are related with Aspergillus ability to form sessile communities referred to as the biofilms. The small compounds known as quorum sensing (QS) molecules allow this microorganism to coordinate all processes taking place during biofilm formation and maturation. In the study presented, the HRMAS (1) H NMR metabolomic approach was applied to define composition of extra and intracellular metabolites produced by biofilmic and planktonic (aka free-swimming) cultures of this microorganism and to evaluate impact of quorum sensing molecule, arachidonic acid (AA) on biofilm formation. The Scanning Electron Microscopy was used to confirm Aspergillus ability to form biofilm in vitro, while multivariate and univariate data analysis was applied to analyze data obtained. The Aspergillus strain was able to form strong biofilm structures in vitro. The statistical analysis revealed significant changes of metabolite production depending on Aspergillus culture type (biofilm vs. plankton), time and presence of QS molecules. The data obtained, if developed, might be used in future NMR diagnostics as markers of Aspergillus biofilm-related infections and lead to shorten time between pathogen identification and introduction of treatment.

  8. 50 CFR 660.140 - Shorebased IFQ Program.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... On or about January 1 each year, QS permit owners will be notified, via the IFQ Web site and their QS... be notified of QP deposits via the IFQ Web site and their QS account. QP and IBQ pounds will be... online QS account. Following the instructions provided on the Web site, the QS permit owner must...

  9. 50 CFR 660.140 - Shorebased IFQ Program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... On or about January 1 each year, QS permit owners will be notified, via the IFQ Web site and their QS... be notified of QP deposits via the IFQ Web site and their QS account. QP and IBQ pounds will be... the online QS account. Following the instructions provided on the Web site, the QS permit owner...

  10. 50 CFR 660.140 - Shorebased IFQ Program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... On or about January 1 each year, QS permit owners will be notified, via the IFQ Web site and their QS... be notified of QP deposits via the IFQ Web site and their QS account. QP and IBQ pounds will be... online QS account. Following the instructions provided on the Web site, the QS permit owner must...

  11. Strain identification and quorum sensing inhibition characterization of marine-derived Rhizobium sp. NAO1

    PubMed Central

    Chang, Hong; Zhu, Xiaoshan; Yu, Shenchen; Chen, Lu; Jin, Hui; Cai, Zhonghua

    2017-01-01

    A novel strategy for combating pathogens is through the ongoing development and use of anti-quorum sensing (QS) treatments such as therapeutic bacteria or their anti-QS substances. Relatively little is known about the bacteria that inhabit the open ocean and of their potential anti-pathogenic attributes; thus, in an initiative to identify these types of therapeutic bacteria, planktonic microbes from the North Atlantic Ocean were collected, isolated, cultured and screened for anti-QS activity. Screening analysis identified one such strain, Rhizobium sp. NAO1. Extracts of Rhizobium sp. NAO1 were identified via ultra-performance liquid chromatography (UPLC) analysis. They were shown to contain N-acyl homoserine lactone (AHL)-based QS analogues (in particular, the N-butyryl homoserine lactone (C4-AHL) analogue) and could disrupt biofilm formation by Pseudomonas aeruginosa PAO1. QS inhibition was confirmed using confocal scanning laser microscopy and growth curves, and it was shown to occur in a dose-dependent manner without affecting bacterial growth. Secondary metabolites of Rhizobium sp. NAO1 inhibited PAO1 pathogenicity by downregulating AHL-mediated virulence factors such as elastase activity and siderophore production. Furthermore, as a result of biofilm structure damage, the secondary metabolite products of Rhizobium sp. NAO1 significantly increased the sensitivity of PAO1 to aminoglycoside antibiotics. Our results demonstrated that Rhizobium sp. strain NAO1 has the ability to disrupt P. aeruginosa PAO1 biofilm architecture, in addition to attenuating P. aeruginosa PAO1 virulence factor production and pathogenicity. Therefore, the newly identified ocean-derived Rhizobium sp. NAO1 has the potential to serve as a QS inhibitor and may be a new microbial resource for drug development.

  12. Anelastic Attenuation and Elastic Scattering of Seismic Waves in the Los Angeles Region

    NASA Astrophysics Data System (ADS)

    Song, X.; Jordan, T. H.

    2013-12-01

    The accuracy of earthquake simulations needed for physics-based seismic hazard analysis depends on good information about crustal structure. For low-frequency (f < 0.3 Hz) simulations, the most important structural parameters are the seismic wave velocities, but as the frequencies increase, seismic wave attenuation becomes more important. We compare attenuation models that have been recently used in the CyberShake hazard model (Graves et al., 2011) and other simulation studies for the Los Angeles region (Olsen et al., 2009; Taborda & Bielak, 2013) with constraints from local earthquake data out to 10 Hz, which include those from Hauksson & Shearer's (2006) attenuation tomography as well as our own measurements. We show that the velocity-attenuation scaling relationship for shear waves employed by CyberShake (QS = 50VS, where VS is in km/s) provides a good approximation to the average crustal structure at f = 0.3 Hz, but it does not capture the lateral variations in QS at shallow depths. Moreover, this frequency-independent model is inconsistent with the high QS values observed throughout most of the crust at f > 1 Hz. The data indicate a frequency-dependent attenuation of the form QS ~ f γ, where 0.5 ≤ γ ≤ 0.8. Anomalously low QS factors are observed at very shallow depths, which can be explained by a combination of anelastic attenuation and elastic scattering. The scattering parameters are roughly consistent with small-scale, near-surface heterogeneities observed in well-logs and seismic reflection surveys in the Los Angeles basin. High-frequency scattering may also play a role in explaining Hauksson & Shearer's (2006) observation that the QP/QS ratio is anomalously low (~ unity). We summarize the observations in a new attenuation and scattering model for the CyberShake region that is laterally heterogeneous and frequency dependent.

  13. -Based Clathrate

    NASA Astrophysics Data System (ADS)

    Anno, Hiroaki; Shirataki, Ritsuko

    2014-06-01

    A polycrystalline silicon-based clathrate of nominal composition Ba8Al15Si31 was prepared by a combination of arc melting and spark plasma sintering. Its thermal stability in air and the effect on the surface of heat treatment in air, which are of practical importance for use of the material at elevated temperatures, were examined for different temperatures (873 K, 973 K, and 1073 K) and heating times (0-480 h). Thermogravimetry and differential thermal analysis in air in the range 300-1523 K indicated that Ba8Al15Si31 in the bulk form had relatively good thermal stability in air at high temperatures. X-ray diffraction measurements, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy revealed that a thin layer of oxide (probably a barium aluminate, BaAl2O4) was formed on the surface by heat treatment in air. The thickness of the oxide layer increased with increasing temperature and heating time. Growth of the oxide layer can be explained well in terms of a diffusion mechanism. The activation energy for oxidation was estimated to be approximately 201 kJ/mol, which is comparable with that for thermal oxidation of silicon. The chemical composition of the interior of the Ba8Al15Si31 was found to be stable to heat treatment in air.

  14. Foundation: Transforming data bases into knowledge bases

    NASA Technical Reports Server (NTRS)

    Purves, R. B.; Carnes, James R.; Cutts, Dannie E.

    1987-01-01

    One approach to transforming information stored in relational data bases into knowledge based representations and back again is described. This system, called Foundation, allows knowledge bases to take advantage of vast amounts of pre-existing data. A benefit of this approach is inspection, and even population, of data bases through an intelligent knowledge-based front-end.

  15. 75 FR 16072 - Fisheries Finance Program; Final Program Notice and Announcement of Availability of Federal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-31

    ... a ratio of the FCRA cost rate and the FCRA cost appropriated. The current cost rate estimate based... percent of the project's depreciated actual cost. For IFQ applicants if the current market value of QS... (FCRA) (2 U.S.C. 661) which requires estimated net loan losses (FCRA cost) to be appropriated at...

  16. Functionalizing Soft Matter for Molecular Communication

    PubMed Central

    2016-01-01

    The information age was enabled by advances in microfabrication and communication theory that allowed information to be processed by electrons and transmitted by electromagnetic radiation. Despite immense capabilities, microelectronics has limited abilities to access and participate in the molecular-based communication that characterizes our biological world. Here, we use biological materials and methods to create components and fabricate devices to perform simple molecular communication functions based on bacterial quorum sensing (QS). Components were created by protein engineering to generate a multidomain fusion protein capable of sending a molecular QS signal, and by synthetic biology to engineer E. coli to receive and report this QS signal. The device matrix was formed using stimuli-responsive hydrogel-forming biopolymers (alginate and gelatin). Assembly of the components within the device matrix was achieved by physically entrapping the cell-based components, and covalently conjugating the protein-based components using the enzyme microbial transglutaminase. We demonstrate simple devices that can send or receive a molecular QS signal to/from the surrounding medium, and a two-component device in which one component generates the signal (i.e., issues a command) that is acted upon by the second component. These studies illustrate the broad potential of biofabrication to generate molecular communication devices. PMID:26501127

  17. Analyzing the Anglo-American Hegemony in the "Times Higher Education" Rankings

    ERIC Educational Resources Information Center

    Kaba, Amadu Jacky

    2012-01-01

    This study analyzes the 2009 "Times Higher Education"-QS top 200 universities in the world. Based on this analysis the study claims that the THS reflects the phenomenon of Anglo American hegemony. The United States with 54 universities and the United Kingdom with 29 dominated the THS. In addition, six out of every ten universities on the…

  18. Influence of operational conditions on the stability of aerobic granules from the perspective of quorum sensing.

    PubMed

    Zhang, Chen; Sun, Supu; Liu, Xiang; Wan, Chunli; Lee, Duu-Jong

    2017-01-25

    Integrated aerobic granules were first cultivated in two sequencing batch reactors (SBRs) (A1 and A2). Then, A1's influent organic loading rate (OLR) was changed from alternating to constant (cycling time was still 6 h), while A2's cycling time varied from 6 to 4 h (influent OLR strategy remained alternating). After 30-day operation since the manipulative alternations, granule breakage happened in two reactors at different operational stages, along with the decrease of granule intensity. Granule diameter in A1 declined from the original 0.84 to 0.32 cm during the whole operation, while granules in A2 dwindled to 0.31 cm on day 22 with similar size to A1. Both the amount of total extracellular polymeric substances (EPSs) and the protein were declining throughout the operation, and the large molecular weight of protein was considered closely related to the stability of aerobic granules. The relative AI-2 level decreased at the same time, and influent OLR strategy might had more evident impact on quorum sensing (QS) ability of sludge compared with starvation period. Combined with microbial results, the decline of total EPS amount in two reactors could be concluded as follows: During the reactor operation, some functional bacteria gradually lost their dominance and were eliminated from the reactors, which finally caused granule disintegration. In summary, the results further confirmed that alternating OLR and proper starvation period were two major factors in effective cultivation and stability of aerobic granules from the perspective of QS.

  19. Bridge aerodynamics and aeroelasticity: A comparison of modeling schemes

    NASA Astrophysics Data System (ADS)

    Wu, Teng; Kareem, Ahsan

    2013-11-01

    Accurate modeling of wind-induced loads on bridge decks is critical to ensure the functionality and survivability of long-span bridges. Over the last few decades, several schemes have emerged to model bridge behavior under winds from an aerodynamic/aeroelastic perspective. A majority of these schemes rely on the quasi-steady (QS) theory. This paper systematically compares and assesses the efficacy of five analytical models available in the literature with a new model presented herein. These models include: QS theory-based model, corrected QS theory-based model, linearized QS theory-based model, semi-empirical linear model, hybrid model, and the proposed modified hybrid model. The ability of these models to capture fluid memory and nonlinear effects either individually or collectively is examined. In addition, their ability to include the effects of turbulence in the approach flow on the bridge behavior is assessed. All models are compared in a consistent manner by utilizing the time domain approach. The underlying role of each model in capturing the physics of bridge behavior under winds is highlighted and the influence of incoming turbulence and its interaction with the bridge deck is examined. A discussion is included that focuses on a number of critical parameters pivotal to the effectiveness of corresponding models.

  20. A Newly Distributed Satellite-based Global Air-sea Surface Turbulent Fluxes Data Set -- GSSTF2b

    NASA Astrophysics Data System (ADS)

    Shie, C.; Nelkin, E.; Ardizzone, J.; Savtchenko, A.; Chiu, L. S.; Adler, R. F.; Lin, I.; Gao, S.

    2010-12-01

    Accurate sea surface turbulent flux measurements are crucial to understanding the global water and energy cycle changes. Remote sensing is a valuable tool for global monitoring of these flux measurements. The GSSTF (Goddard Satellite-based Surface Turbulent Fluxes) algorithm was thus developed and applied to remote sensing research and applications. The recently revived and produced daily global (1ox1o) GSSTF2b (Version-2b) dataset (July 1987-December 2008) is currently under processing for an official distribution by NASA GES DISC (Goddard Earth Sciences Data and Information Services Center) due by the end of this month (September, 2010). Like its predecessor product GSSTF2, GSSTF2b is expected to provide the scientific community a longer-period and useful turbulent surface flux dataset for global energy and water cycle research, as well as regional and short period data analyses. We have recently been funded by the NASA/MEaSUREs Program to resume processing of the GSSTF with an objective of continually producing an up-to-date uniform and reliable dataset of sea surface turbulent fluxes, derived from improved input remote sensing data and model reanalysis, which would continue to be useful for global energy and water flux research and applications. The daily global (1ox1o) GSSTF2b dataset has lately been produced using upgraded and improved input datasets such as the Special Sensor Microwave Imager (SSM/I) Version-6 (V6) product (including brightness temperature [Tb], total precipitable water [W], and wind speed [U]) and the NCEP/DOE Reanalysis-2 (R2) product (including sea skin temperature [SKT], 2-meter air temperature [T2m], and sea level pressure [SLP]). The input datasets previously used for producing the GSSTF2 product were the SSM/I Version-4 (V4) product and the NCEP Reanalysis-1 (R1) product. The newly produced GSSTF2b was found to generally agree better with available ship measurements obtained from several field experiments in 1999 than its counterpart

  1. Identification of Five Structurally Unrelated Quorum-Sensing Inhibitors of Pseudomonas aeruginosa from a Natural-Derivative Database

    PubMed Central

    Tan, Sean Yang-Yi; Chua, Song-Lin; Chen, Yicai; Rice, Scott A.; Kjelleberg, Staffan; Nielsen, Thomas E.; Givskov, Michael

    2013-01-01

    Bacteria communicate by means of small signal molecules in a process termed quorum sensing (QS). QS enables bacteria to organize their activities at the population level, including the coordinated secretion of virulence factors. Certain small-molecule compounds, known as quorum-sensing inhibitors (QSIs), have been shown to effectively block QS and subsequently attenuate the virulence of Pseudomonas aeruginosa, as well as increasing its susceptibility to both antibiotics and the immune system. In this study, a structure-based virtual screening (SB-VS) approach was used for the discovery of novel QSI candidates. Three-dimensional structures of 3,040 natural compounds and their derivatives were obtained, after which molecular docking was performed using the QS receptor LasR as a target. Based on docking scores and molecular masses, 22 compounds were purchased to determine their efficacies as quorum-sensing inhibitors. Using a live reporter assay for quorum sensing, 5 compounds were found to be able to inhibit QS-regulated gene expression in P. aeruginosa in a dose-dependent manner. The most promising compound, G1, was evaluated by isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic analysis, and it was found to significantly affect the abundance of 46 proteins (19 were upregulated; 27 were downregulated) in P. aeruginosa PAO1. It specifically reduced the expression of several quorum-sensing-regulated virulence factors, such as protease IV, chitinase, and pyoverdine synthetases. G1 was also able to reduce extracellular DNA release and inhibited the secretion of the virulence factor, elastase, whose expression is regulated by LasR. These results demonstrate the utility of SB-VS for the discovery of target-specific QSIs. PMID:24002091

  2. Nanoporous Superhydrophobic Coatings that Promote the Extended Release of Water-Labile Quorum Sensing Inhibitors and Enable Long-Term Modulation of Quorum Sensing in Staphylococcus aureus

    PubMed Central

    2015-01-01

    Materials and coatings that inhibit bacterial colonization are of interest in a broad range of biomedical, environmental, and industrial applications. In view of the rapid increase in bacterial resistance to conventional antibiotics, the development of new strategies that target nonessential pathways in bacterial pathogens—and that thereby limit growth and reduce virulence through nonbiocidal means—has attracted considerable attention. Bacterial quorum sensing (QS) represents one such target, and is intimately connected to virulence in many human pathogens. Here, we demonstrate that the properties of nanoporous, polymer-based superhydrophobic coatings can be exploited to host and subsequently sustain the extended release of potent and water-labile peptide-based inhibitors of QS (QSIs) in Staphylococcus aureus. Our results demonstrate that these peptidic QSIs can be released into surrounding media for periods of at least 8 months, and that they strongly inhibit agr-based QS in S. aureus for at least 40 days. These results also suggest that these extremely nonwetting coatings can confer protection against the rapid hydrolysis of these water-labile peptides, thereby extending their useful lifetimes. Finally, we demonstrate that these peptide-loaded superhydrophobic coatings can strongly modulate the QS-controlled formation of biofilm in wild-type S. aureus. These nanoporous superhydrophobic films provide a new, useful, and nonbiocidal approach to the design of coatings that attenuate bacterial virulence. This approach has the potential to be general, and could prove suitable for the encapsulation, protection, and release of other classes of water-sensitive agents. We anticipate that the materials, strategies, and concepts reported here will enable new approaches to the long-term attenuation of QS and associated bacterial phenotypes in a range of basic research and applied contexts. PMID:26501126

  3. Identification of five structurally unrelated quorum-sensing inhibitors of Pseudomonas aeruginosa from a natural-derivative database.

    PubMed

    Tan, Sean Yang-Yi; Chua, Song-Lin; Chen, Yicai; Rice, Scott A; Kjelleberg, Staffan; Nielsen, Thomas E; Yang, Liang; Givskov, Michael

    2013-11-01

    Bacteria communicate by means of small signal molecules in a process termed quorum sensing (QS). QS enables bacteria to organize their activities at the population level, including the coordinated secretion of virulence factors. Certain small-molecule compounds, known as quorum-sensing inhibitors (QSIs), have been shown to effectively block QS and subsequently attenuate the virulence of Pseudomonas aeruginosa, as well as increasing its susceptibility to both antibiotics and the immune system. In this study, a structure-based virtual screening (SB-VS) approach was used for the discovery of novel QSI candidates. Three-dimensional structures of 3,040 natural compounds and their derivatives were obtained, after which molecular docking was performed using the QS receptor LasR as a target. Based on docking scores and molecular masses, 22 compounds were purchased to determine their efficacies as quorum-sensing inhibitors. Using a live reporter assay for quorum sensing, 5 compounds were found to be able to inhibit QS-regulated gene expression in P. aeruginosa in a dose-dependent manner. The most promising compound, G1, was evaluated by isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic analysis, and it was found to significantly affect the abundance of 46 proteins (19 were upregulated; 27 were downregulated) in P. aeruginosa PAO1. It specifically reduced the expression of several quorum-sensing-regulated virulence factors, such as protease IV, chitinase, and pyoverdine synthetases. G1 was also able to reduce extracellular DNA release and inhibited the secretion of the virulence factor, elastase, whose expression is regulated by LasR. These results demonstrate the utility of SB-VS for the discovery of target-specific QSIs.

  4. Nanoporous Superhydrophobic Coatings that Promote the Extended Release of Water-Labile Quorum Sensing Inhibitors and Enable Long-Term Modulation of Quorum Sensing in Staphylococcus aureus.

    PubMed

    Kratochvil, Michael J; Tal-Gan, Yftah; Yang, Tian; Blackwell, Helen E; Lynn, David M

    2015-10-12

    Materials and coatings that inhibit bacterial colonization are of interest in a broad range of biomedical, environmental, and industrial applications. In view of the rapid increase in bacterial resistance to conventional antibiotics, the development of new strategies that target nonessential pathways in bacterial pathogens-and that thereby limit growth and reduce virulence through nonbiocidal means-has attracted considerable attention. Bacterial quorum sensing (QS) represents one such target, and is intimately connected to virulence in many human pathogens. Here, we demonstrate that the properties of nanoporous, polymer-based superhydrophobic coatings can be exploited to host and subsequently sustain the extended release of potent and water-labile peptide-based inhibitors of QS (QSIs) in Staphylococcus aureus. Our results demonstrate that these peptidic QSIs can be released into surrounding media for periods of at least 8 months, and that they strongly inhibit agr-based QS in S. aureus for at least 40 days. These results also suggest that these extremely nonwetting coatings can confer protection against the rapid hydrolysis of these water-labile peptides, thereby extending their useful lifetimes. Finally, we demonstrate that these peptide-loaded superhydrophobic coatings can strongly modulate the QS-controlled formation of biofilm in wild-type S. aureus. These nanoporous superhydrophobic films provide a new, useful, and nonbiocidal approach to the design of coatings that attenuate bacterial virulence. This approach has the potential to be general, and could prove suitable for the encapsulation, protection, and release of other classes of water-sensitive agents. We anticipate that the materials, strategies, and concepts reported here will enable new approaches to the long-term attenuation of QS and associated bacterial phenotypes in a range of basic research and applied contexts.

  5. Prediction of virological response by pretreatment hepatitis B virus reverse transcriptase quasispecies heterogeneity: the advantage of using next-generation sequencing.

    PubMed

    Han, Y; Gong, L; Sheng, J; Liu, F; Li, X-H; Chen, L; Yu, D-M; Gong, Q-M; Hao, P; Zhang, X-X

    2015-08-01

    Prediction of antiviral efficacy prior to treatment remains largely unavailable. We have previously demonstrated the clinical value of on-treatment hepatitis B virus (HBV) reverse transcriptase (RT) quasispecies (QS) evolution patterns. In this study, we aimed to elucidate the relevance for prediction of pretreatment HBV RT QS characteristics by comparing the performance of next-generation sequencing (NGS) and clone-based Sanger sequencing (CBS). Thirty-six lamivudine-treated patients were retrospectively studied, including 18 responders and 18 non-responders. CBS and NGS data of pretreatment serum HBV were used to generate RT QS genetic complexity and diversity scores, according to our previous studies. The ability of both methods to predict responsiveness was evaluated with receiver operating characteristic (ROC) curves. A cut-off value was generated on the basis of prediction ability. Responders had significantly higher pretreatment RT QS genetic complexity and diversity (in the first two parts, which overlapped with the S gene, at both the nucleotide and amino acid levels) than non-responders by NGS-based testing. NGS-based algorithms predicted response better than CBS in the ROC curve analysis. The mean distance of the second contig had the highest area under the curve (AUC) value. When the cut-off value was set to 0.007186, the difference between survival curves was significant (p 0.0090). Pretreatment HBV RT QS heterogeneity in the overlapping region of the RT and S genes could be a predictor of antiviral efficacy. NGS improves the predictions of virological outcomes relative to CBS algorithms. This may have important implications for the clinical management of subjects chronically infected with HBV.

  6. A phase-locked loop model of the response of the postural control system to periodic platform motion.

    PubMed

    Schilling, Robert J; Robinson, Charles J

    2010-06-01

    A phase-locked loop (PLL) model of the response of the postural control system to periodic platform motion is proposed. The PLL model is based on the hypothesis that quiet standing (QS) postural sway can be characterized as a weak sinusoidal oscillation corrupted with noise. Because the signal to noise ratio is quite low, the characteristics of the QS oscillator are not measured directly from the QS sway, instead they are inferred from the response of the oscillator to periodic motion of the platform. When a sinusoidal stimulus is applied, the QS oscillator changes speed as needed until its frequency matches that of the platform, thus achieving phase lock in a manner consistent with a PLL control mechanism. The PLL model is highly effective in representing the frequency, amplitude, and phase shift of the sinusoidal component of the phase-locked response over a range of platform frequencies and amplitudes. Qualitative analysis of the PLL control mechanism indicates that there is a finite range of frequencies over which phase lock is possible, and that the size of this capture range decreases with decreasing platform amplitude. The PLL model was tested experimentally using nine healthy subjects and the results reveal good agreement with a mean phase shift error of 13.7 degrees and a mean amplitude error of 0.8 mm.

  7. Structural insights into a novel interkingdom signaling circuit by cartography of the ligand-binding sites of the homologous quorum sensing LuxR-family.

    PubMed

    Covaceuszach, Sonia; Degrassi, Giuliano; Venturi, Vittorio; Lamba, Doriano

    2013-10-15

    Recent studies have identified a novel interkingdom signaling circuit, via plant signaling molecules, and a bacterial sub-family of LuxR proteins, bridging eukaryotes and prokaryotes. Indeed pivotal plant-bacteria interactions are regulated by the so called Plant Associated Bacteria (PAB) LuxR solo regulators that, although closely related to the quorum sensing (QS) LuxR family, do not bind or respond to canonical quorum sensing N-acyl homoserine lactones (AHLs), but only to specific host plant signal molecules. The large body of structural data available for several members of the QS LuxR family complexed with different classes of ligands (AHLs and other compounds), has been exploited to dissect the cartography of their regulatory domains through structure-based multiple sequence alignments, structural superimposition and a comparative analysis of the contact residues involved in ligand binding. In the absence of experimentally determined structures of members of the PAB LuxR solos subfamily, an homology model of its prototype OryR is presented, aiming to elucidate the architecture of its ligand-binding site. The obtained model, in combination with the cartography of the regulatory domains of the homologous QS LuxRs, provides novel insights into the 3D structure of its ligand-binding site and unveils the probable molecular determinants responsible for differences in selectivity towards specific host plant signal molecules, rather than to canonical QS compounds.

  8. Screening of certain medicinal plants from India for their anti-quorum sensing activity.

    PubMed

    Zahin, Maryam; Hasan, Sameena; Aqil, Farrukh; Khan, Mohd Sajjad Ahmad; Husain, Fohad Mabood; Ahmad, Iqbal

    2010-12-01

    Discovery of quorum sensing (QS) system to coordinate virulence and biofilm formation in bacterial pathogens has triggered search for safe, stable and non-toxic anti-QS compounds from natural products. Ethanolic extracts of 24 Indian medicinal plants were tested by agar well and disc diffusion assay for anti-QS activity using Chromobacterium violaceum (CV12472 and CVO26) reporter strains. AHL from C. violaceum CV31532 was isolated and partially purified for its use in CVO26 based bioassay. Effect on swarming-motility of Pseudomonas aeruginosa (PAO1) was also recorded at sub-MIC concentrations of extracts. Of the 24 medicinal plants screened Hemidesmus indicus (L.) Schult (root), Holarrhena antidysenterica (Roth) A.DC. (bark), Mangifera indica L. (seed) Punica granatum L. (pericarp) and Psoralea corylifolia L. (seed) demonstrated varying level of inhibition of violacein production in the reporter strains. Moreover, a significant reduction in swarms was recorded over control. The inhibition of violacein production and swarming motility may be due to direct or indirect interference on QS by active constituents or the interactive effect of different phytocompounds present in the extracts. These plant extracts may be selected for activity guided fractionation to identify and characterize the active principle.

  9. Enterobacter asburiae Strain L1: Complete Genome and Whole Genome Optical Mapping Analysis of a Quorum Sensing Bacterium

    PubMed Central

    Lau, Yin Yin; Yin, Wai-Fong; Chan, Kok-Gan

    2014-01-01

    Enterobacter asburiae L1 is a quorum sensing bacterium isolated from lettuce leaves. In this study, for the first time, the complete genome of E. asburiae L1 was sequenced using the single molecule real time sequencer (PacBio RSII) and the whole genome sequence was verified by using optical genome mapping (OpGen) technology. In our previous study, E. asburiae L1 has been reported to produce AHLs, suggesting the possibility of virulence factor regulation which is quorum sensing dependent. This evoked our interest to study the genome of this bacterium and here we present the complete genome of E. asburiae L1, which carries the virulence factor gene virK, the N-acyl homoserine lactone-based QS transcriptional regulator gene luxR and the N-acyl homoserine lactone synthase gene which we firstly named easI. The availability of the whole genome sequence of E. asburiae L1 will pave the way for the study of the QS-mediated gene expression in this bacterium. Hence, the importance and functions of these signaling molecules can be further studied in the hope of elucidating the mechanisms of QS-regulation in E. asburiae. To the best of our knowledge, this is the first documentation of both a complete genome sequence and the establishment of the molecular basis of QS properties of E. asburiae. PMID:25196111

  10. Involvement of N-acylhomoserine lactones throughout plant infection by Erwinia carotovora subsp. atroseptica (Pectobacterium atrosepticum).

    PubMed

    Smadja, Bruno; Latour, Xavier; Faure, Denis; Chevalier, Sylvie; Dessaux, Yves; Orange, Nicole

    2004-11-01

    Erwinia carotovora subsp. atroseptica is responsible for potato blackleg disease in the field and tuber soft rot during crop storage. The process leading to the disease occurs in two phases: a primary invasion step followed by a maceration step. Bacteria-to-bacteria communication is associated with a quorum-sensing (QS) process based on the production of N-acylhomoserine lactones (HSL). The role of HSL throughout plant infection was analyzed. To this purpose, HSL produced by a specific E. carotovora subsp. atroseptica wild-type strain, which was particularly virulent on potato, were identified. A derivative of this strain that expressed an HSL lactonase gene and produced low amounts of HSL was generated. The comparison of these strains allowed the evaluation of the role of HSL and QS in disease establishment and development. Bacterial growth and motility; activity of proteins secreted by type I, II, and III systems; and hypersensitive and maceration reactions were evaluated. Results indicated that HSL production and QS regulate only those traits involved in the second stage of the host plant infection (i.e., tissue maceration) and hypersensitive response in nonhost tobacco plants. Therefore, the use of QS quenching strategies for biological control in E. carotovora subsp. atroseptica cannot prevent initial infection and multiplication of this pathogen.

  11. Quillaja Saponin Variants with Central Glycosidic Linkage Modifications Exhibit Distinct Conformations and Adjuvant Activities

    PubMed Central

    Walkowicz, William E.; Fernández-Tejada, Alberto; George, Constantine; Corzana, Francisco; Jiménez-Barbero, Jesús; Gin, David Y.

    2016-01-01

    Immunological adjuvants such as the saponin natural product QS-21 help stimulate the immune response to co-administered antigens and have become increasingly important in the development of prophylactic and therapeutic vaccines. However, clinical use of QS21 is encumbered by chemical instability, dose-limiting toxicity, and low-yielding purification from the natural source. Previous studies of structure–activity relationships in the four structural domains of QS-21 have led to simplified, chemically stable variants that retain potent adjuvant activity and low toxicity in mouse vaccination models. However, modification of the central glycosyl ester linkage has not yet been explored. Herein, we describe the design, synthesis, immunologic evaluation, and molecular dynamics analysis of a series of novel QS-21 variants with different linker lengths, stereochemistry, and flexibility to investigate the role of this linkage in saponin adjuvant activity and conformation. Despite relatively conservative structural modifications, these variants exhibit striking differences in in vivo adjuvant activity that correlate with specific conformational preferences. These results highlight the junction of the triterpene and linear oligosaccharide domains as playing a critical role in the immunoadjuvant activity of the Quillaja saponins and also suggest a mechanism of action involving interaction with a discrete macromolecular target, in contrast to the non-specific mechanisms of emulsion-based adjuvants. PMID:27014435

  12. Dynamics of AHL mediated quorum sensing under flow and non-flow conditions

    NASA Astrophysics Data System (ADS)

    Meyer, Andrea; Megerle, Judith A.; Kuttler, Christina; Müller, Johannes; Aguilar, Claudio; Eberl, Leo; Hense, Burkhard A.; Rädler, Joachim O.

    2012-04-01

    Quorum sensing (QS) describes the capability of microbes to communicate with each other by the aid of small molecules. Here we investigate the dynamics of QS-regulated gene expression induced by acylhomoserine lactones (AHLs) in Pseudomonas putida IsoF containing a green fluorescent protein-based AHL reporter. The fluorescence time course of individual colonies is monitored following the external addition of a defined AHL concentration to cells which had previously reached the QS-inactive state in AHL-free medium. Using a microfluidic setup the experiment is performed both under flow and non-flow conditions. We find that without supplying external AHL gene expression is induced without flow while flow suppresses the induction. Both without and with flow, at a low AHL concentration the fluorescence onset is significantly delayed while fluorescence starts to increase directly upon the addition of AHL at a high concentration. The differences between no flow and flow can be accounted for using a two-compartment model. This indicates AHL accumulation in a volume which is not affected by the flow. The experiments furthermore show significant cell-to-cell and colony-to-colony variability which is discussed in the context of a compartmentalized QS mechanism.

  13. Quantifying Regional Body Wave Attenuation in a Seismic Prone Zone of Northeast India

    NASA Astrophysics Data System (ADS)

    Bora, Nilutpal; Biswas, Rajib

    2017-03-01

    We evaluated the body wave attenuation parameter in Kopili region of northeast India. Using the modified algorithm of coda normalization method, we delineated frequency-dependent attenuation for both P and S waves. Taking more than 300 seismograms as input, we comprehensively studied microearthquake spectra in the frequency range of 1.5-12 Hz. The estimated values of {Q}_{P}^{-1} and {Q}_{S}^{-1} show strong frequency dependence. Based on this, we formulated empirical relationships corresponding to {Q}_{P}^{-1} and {Q}_{S}^{-1} for the study region. The relationships emerge to be {Q}_{P}^{-1} = ( {23.8 ± 6} ) × 10^{-3} {f}^{{( {-1.2 ± 0.008} )}} and {Q}_{S}^{-1} = ( {10.2 ± 2} ) × 10^{-3} {f}^{{( {-1.3 ± 0.02} )}} , respectively. The ratio {Q}_{P}^{-1} /{Q}_{S}^{-1} is found to be larger than unity for the entire frequency band which implies profound seismic activity and macroscale heterogeneity prevailing in the region. The study may act as the building block towards determination of source parameter and hazard-related studies in the region.

  14. Butanol production employing fed-batch fermentation by Clostridium acetobutylicum GX01 using alkali-pretreated sugarcane bagasse hydrolysed by enzymes from Thermoascus aurantiacus QS 7-2-4.

    PubMed

    Pang, Zong-Wen; Lu, Wei; Zhang, Hui; Liang, Zheng-Wu; Liang, Jing-Juan; Du, Liang-Wei; Duan, Cheng-Jie; Feng, Jia-Xun

    2016-07-01

    Sugarcane bagasse (SB) is a potential feedstock for butanol production. However, biological production of butanol from SB is less economically viable. In this study, evaluation of eight pretreatments on SB showed that alkali pretreatment efficiently removed lignin from SB while retaining the intact native structure of the released microfibrils. In total, 99% of cellulose and 100% of hemicellulose in alkali-pretreated SB were hydrolysed by enzymes from Thermoascus aurantiacus. The hydrolysate was used to produce butanol in a fed-batch fermentation by Clostridium acetobutylicum. At 60h, 14.17 and 21.11gL(-1) of butanol and acetone-butanol-ethanol (ABE) were produced from 68.89gL(-1) of total sugars, respectively, yielding 0.22 and 0.33gg(-1) of sugars. The maximum yield of butanol and ABE reached 15.4g and 22.9g per 100g raw SB, respectively. This established process may have potential application for butanol production from SB.

  15. Variability in biofilm formation correlates with hydrophobicity and quorum sensing among Vibrio parahaemolyticus isolates from food contact surfaces and the distribution of the genes involved in biofilm formation.

    PubMed

    Mizan, Md Furkanur Rahaman; Jahid, Iqbal Kabir; Kim, Minhui; Lee, Ki-Hoon; Kim, Tae Jo; Ha, Sang-Do

    2016-01-01

    Vibrio parahaemolyticus is one of the leading foodborne pathogens causing seafood contamination. Here, 22 V. parahaemolyticus strains were analyzed for biofilm formation to determine whether there is a correlation between biofilm formation and quorum sensing (QS), swimming motility, or hydrophobicity. The results indicate that the biofilm formation ability of V. parahaemolyticus is positively correlated with cell surface hydrophobicity, autoinducer (AI-2) production, and protease activity. Field emission scanning electron microscopy (FESEM) showed that strong-biofilm-forming strains established thick 3-D structures, whereas poor-biofilm-forming strains produced thin inconsistent biofilms. In addition, the distribution of the genes encoding pandemic clone factors, type VI secretion systems (T6SS), biofilm functions, and the type I pilus in the V. parahaemolyticus seafood isolates were examined. Biofilm-associated genes were present in almost all the strains, irrespective of other phenotypes. These results indicate that biofilm formation on/in seafood may constitute a major factor in the dissemination of V. parahaemolyticus and the ensuing diseases.

  16. Comparative Systems Biology Analysis To Study the Mode of Action of the Isothiocyanate Compound Iberin on Pseudomonas aeruginosa

    PubMed Central

    Tan, Sean Yang-Yi; Liu, Yang; Chua, Song Lin; Vejborg, Rebecca Munk; Jakobsen, Tim Holm; Chew, Su Chuen; Li, Yingying; Nielsen, Thomas E.; Tolker-Nielsen, Tim; Givskov, Michael

    2014-01-01

    Food is now recognized as a natural resource of novel antimicrobial agents, including those that target the virulence mechanisms of bacterial pathogens. Iberin, an isothiocyanate compound from horseradish, was recently identified as a quorum-sensing inhibitor (QSI) of the bacterial pathogen Pseudomonas aeruginosa. In this study, we used a comparative systems biology approach to unravel the molecular mechanisms of the effects of iberin on QS and virulence factor expression of P. aeruginosa. Our study shows that the two systems biology methods used (i.e., RNA sequencing and proteomics) complement each other and provide a thorough overview of the impact of iberin on P. aeruginosa. RNA sequencing-based transcriptomics showed that iberin inhibits the expression of the GacA-dependent small regulatory RNAs RsmY and RsmZ; this was verified by using gfp-based transcriptional reporter fusions with the rsmY or rsmZ promoter regions. Isobaric tags for relative and absolute quantitation (iTRAQ) proteomics showed that iberin reduces the abundance of the LadS protein, an activator of GacS. Taken together, the findings suggest that the mode of QS inhibition in iberin is through downregulation of the Gac/Rsm QS network, which in turn leads to the repression of QS-regulated virulence factors, such as pyoverdine, chitinase, and protease IV. Lastly, as expected from the observed repression of small regulatory RNA synthesis, we also show that iberin effectively reduces biofilm formation. This suggests that small regulatory RNAs might serve as potential targets in the future development of therapies against pathogens that use QS for controlling virulence factor expression and assume the biofilm mode of growth in the process of causing disease. PMID:25155599

  17. The Pseudomonas aeruginosa Global Regulator VqsR Directly Inhibits QscR To Control Quorum-Sensing and Virulence Gene Expression

    PubMed Central

    Deng, Xin; Ji, Quanjiang; Sun, Fei; Shen, Tuo; He, Chuan

    2012-01-01

    The opportunistic pathogen Pseudomonas aeruginosa has at least three quorum-sensing (QS) systems, including the acyl-homoserine lactone (acyl-HSL)-mediated las and rhl systems, as well as the 2-alkyl-4(1H)-quinolone (AHQ) signal-based system. A group of key regulators of these QS systems have been identified, such as qteE, vqsM, vqsR, and vfr. However, the underlying regulatory mechanisms of these QS systems are not yet fully understood. Here, using electrophoretic mobility shift assays, we demonstrated that VqsR indirectly regulates acyl-HSL systems but specifically binds to the qscR promoter region, which indicates that VqsR influences QS-controlled pathways through QscR. Through a dye-based DNase I footprint assay, we showed that VqsR interacts with an inverted repeat (IR) motif (TCGCCN8GGCGA, where N is any nucleotide) in the promoter region of qscR. A genome-wide search identified 50 other promoter regions carrying the same putative IR motif. The recombinant VqsR protein exists as a homodimer in solution. In addition, using a qscR-lux reporter assay and Northern blot hybridization, we found that the transcription level of qscR increased 4-fold in the vqsR deletion strain compared to the wild-type PAO1 strain, indicating vqsR as a negative regulator of qscR. Taken together, these findings provide new insights into the complex regulation network of QS systems in P. aeruginosa. PMID:22505688

  18. Establishment of quantitative sequencing and filter contact vial bioassay for monitoring pyrethroid resistance in the common bed bug, Cimex lectularius.

    PubMed

    Seong, Keon Mook; Lee, Da-Young; Yoon, Kyong Sup; Kwon, Deok Ho; Kim, Heung Chul; Klein, Terry A; Clark, J Marshall; Lee, Si Hyeock

    2010-07-01

    Two point mutations (V419L and L925I) in the voltage-sensitive sodium channel alpha-subunit gene have been identified in deltamethrin-resistant bed bugs. A quantitative sequencing (QS) protocol was developed to establish a population-based genotyping method as a molecular resistance-monitoring tool based on the frequency of the two mutations. The nucleotide signal ratio at each mutation site was generated from sequencing chromatograms and plotted against the corresponding resistance allele frequency. Frequency prediction equations were generated from the plots by linear regression, and the signal ratios were shown to highly correlate with resistance allele frequencies (r2 > 0.9928). As determined by QS, neither mutation was found in a bed bug population collected in 1993. Populations collected in recent years (2007-2009), however, exhibited completely or nearly saturating L925I mutation frequencies and highly variable frequencies of the V419L mutation. In addition to QS, the filter contact vial bioassay (FCVB) method was established and used to determine the baseline susceptibility and resistance of bed bugs to deltamethrin and lambda-cyhalothrin. A pyrethroid-resistant strain showed >9,375- and 6,990-fold resistance to deltamethrin and lambda-cyhalothrin, respectively. Resistance allele frequencies in different bed bug populations predicted by QS correlated well with the FCVB results, confirming the roles of the two mutations in pyrethroid resistance. Taken together, employment of QS in conjunction with FCVB should greatly facilitate the detection and monitoring of pyrethroid-resistant bed bugs in the field. The advantages of FCVB as an on-site resistance-monitoring tool are discussed.

  19. Team-Based Learning

    ERIC Educational Resources Information Center

    Michaelsen, Larry K.; Sweet, Michael

    2011-01-01

    Team-based learning (TBL), when properly implemented, includes many, if not all, of the common elements of evidence-based best practices. To explain this, a brief overview of TBL is presented. The authors examine the relationship between the best practices of evidence-based teaching and the principles that constitute team-based learning. (Contains…

  20. TARDEC Industrial Base Overview

    DTIC Science & Technology

    2010-11-30

    TARDEC Industrial Base Overview Randal Gaereminck, Associate Director, Industrial Base, Manufacturing, Logistics, & Value Engineering TARDEC...8-98) Prescribed by ANSI Std Z39-18 PURPOSE 2 To inform the conference attendees about TARDEC’s Industrial Base Mission and Capabilities AGENDA 3...Partnership • IBIT Policy Benefits • IBIT Mission • Industrial Base Engineering Support • Sustainment Engineering – Obsolescence • Industrial Base Engineering

  1. Ln₃FeGaQ₇: A new series of transition-metal rare-earth chalcogenides

    SciTech Connect

    Yin, Wenlong; Wang, Wendong; Kang, Lei; Lin, Zheshuai; Feng, Kai; Shi, Youguo; and others

    2013-06-01

    A new series of transition-metal rare-earth chalcogenides, Ln₃FeGaQ₇ (Ln=Nd, Sm, Gd, Dy, Q=S; Ln=Nd, Gd, Dy, Q=Se), have been synthesized by solid state reactions. They are isostructural and crystallize in the space group P6₃. They adopt a three-dimensional framework composed of LnQ₇ monocapped trigonal prisms with the interesting 1[FeS₃]⁴⁻ chains and isolated GaQ₄ tetrahedra lying in two sets of channels in the framework. Magnetic susceptibility measurements on Ln₃FeGaQ₇ (Ln=Gd, Dy; Q=S, Se) indicate that they are paramagnetic and obey the Curie–Weiss law. Based on the diffuse reflectance spectra, Ln₃FeGaQ₇ (Ln=Gd, Dy; Q=S, Se) should have band gaps smaller than 0.5 eV. Electronic conductivity measurement on Dy₃FeGaSe₇ demonstrates semiconducting behavior with σ₃₀₀=0.124 S/cm. The first-principles calculations were also performed to study the electronic structures of these compounds. - Graphical abstract: Ln₃FeGaQ₇ adopt a three-dimensional framework composed of LnQ₇ monocapped trigonal prisms with interesting 1[FeS₃]⁴⁻ chains and isolated GaQ₄ tetrahedra lying in two sets of channels in the framework. Highlights: • New compounds, Ln₃FeGaQ₇ (Ln=Nd, Sm, Gd, Dy, Q=S, Se), were synthesized. • They are isostructural and crystallize in the noncentrosymmetric space group P6₃. • They adopt a three-dimensional framework built by LnQ₇ monocapped trigonal prisms. • Ln₃FeGaQ₇ (Ln=Gd, Dy; Q=S, Se) are paramagnetic and obey the Curie–Weiss law. • Electronic conductivity of Dy₃FeGaSe₇ shows semiconducting behavior.

  2. Impairment of Pseudomonas aeruginosa Biofilm Resistance to Antibiotics by Combining the Drugs with a New Quorum-Sensing Inhibitor

    PubMed Central

    Lajoie, Barbora; El Hage, Salome; Baziard, Genevieve; Roques, Christine

    2015-01-01

    Pseudomonas aeruginosa plays an important role in chronic lung infections among patients with cystic fibrosis (CF) through its ability to form antibiotic-resistant biofilms. In P. aeruginosa, biofilm development and the production of several virulence factors are mainly regulated by the rhl and las quorum-sensing (QS) systems, which are controlled by two N-acyl-homoserine lactone signal molecules. In a previous study, we discovered an original QS inhibitor, N-(2-pyrimidyl)butanamide, called C11, based on the structure of C4-homoserine lactone, and found that it is able to significantly inhibit P. aeruginosa biofilm formation. However, recent data indicate that P. aeruginosa grows under anaerobic conditions and forms biofilms in the lungs of CF patients that are denser and more robust than those formed under aerobic conditions. Our confocal microscopy observations of P. aeruginosa biofilms developed under aerobic and anaerobic conditions confirmed that the biofilms formed under these two conditions have radically different architectures. C11 showed significant dose-dependent antibiofilm activity on biofilms grown under both aerobic and anaerobic conditions, with a greater inhibitory effect being seen under conditions of anaerobiosis. Gene expression analyses performed by quantitative reverse transcriptase PCR showed that C11 led to the significant downregulation of rhl QS regulatory genes but also to the downregulation of both las QS regulatory genes and QS system-regulated virulence genes, rhlA and lasB. Furthermore, the activity of C11 in combination with antibiotics against P. aeruginosa biofilms was tested, and synergistic antibiofilm activity between C11 and ciprofloxacin, tobramycin, and colistin was obtained under both aerobic and anaerobic conditions. This study demonstrates that C11 may increase the efficacy of treatments for P. aeruginosa infections by increasing the susceptibility of biofilms to antibiotics and by attenuating the pathogenicity of the

  3. A bioinformatic survey of distribution, conservation, and probable functions of LuxR solo regulators in bacteria.

    PubMed

    Subramoni, Sujatha; Florez Salcedo, Diana Vanessa; Suarez-Moreno, Zulma R

    2015-01-01

    LuxR solo transcriptional regulators contain both an autoinducer binding domain (ABD; N-terminal) and a DNA binding Helix-Turn-Helix domain (HTH; C-terminal), but are not associated with a cognate N-acyl homoserine lactone (AHL) synthase coding gene in the same genome. Although a few LuxR solos have been characterized, their distributions as well as their role in bacterial signal perception and other processes are poorly understood. In this study we have carried out a systematic survey of distribution of all ABD containing LuxR transcriptional regulators (QS domain LuxRs) available in the InterPro database (IPR005143), and identified those lacking a cognate AHL synthase. These LuxR solos were then analyzed regarding their taxonomical distribution, predicted functions of neighboring genes and the presence of complete AHL-QS systems in the genomes that carry them. Our analyses reveal the presence of one or multiple predicted LuxR solos in many proteobacterial genomes carrying QS domain LuxRs, some of them harboring genes for one or more AHL-QS circuits. The presence of LuxR solos in bacteria occupying diverse environments suggests potential ecological functions for these proteins beyond AHL and interkingdom signaling. Based on gene context and the conservation levels of invariant amino acids of ABD, we have classified LuxR solos into functionally meaningful groups or putative orthologs. Surprisingly, putative LuxR solos were also found in a few non-proteobacterial genomes which are not known to carry AHL-QS systems. Multiple predicted LuxR solos in the same genome appeared to have different levels of conservation of invariant amino acid residues of ABD questioning their binding to AHLs. In summary, this study provides a detailed overview of distribution of LuxR solos and their probable roles in bacteria with genome sequence information.

  4. A bioinformatic survey of distribution, conservation, and probable functions of LuxR solo regulators in bacteria

    PubMed Central

    Subramoni, Sujatha; Florez Salcedo, Diana Vanessa; Suarez-Moreno, Zulma R.

    2015-01-01

    LuxR solo transcriptional regulators contain both an autoinducer binding domain (ABD; N-terminal) and a DNA binding Helix-Turn-Helix domain (HTH; C-terminal), but are not associated with a cognate N-acyl homoserine lactone (AHL) synthase coding gene in the same genome. Although a few LuxR solos have been characterized, their distributions as well as their role in bacterial signal perception and other processes are poorly understood. In this study we have carried out a systematic survey of distribution of all ABD containing LuxR transcriptional regulators (QS domain LuxRs) available in the InterPro database (IPR005143), and identified those lacking a cognate AHL synthase. These LuxR solos were then analyzed regarding their taxonomical distribution, predicted functions of neighboring genes and the presence of complete AHL-QS systems in the genomes that carry them. Our analyses reveal the presence of one or multiple predicted LuxR solos in many proteobacterial genomes carrying QS domain LuxRs, some of them harboring genes for one or more AHL-QS circuits. The presence of LuxR solos in bacteria occupying diverse environments suggests potential ecological functions for these proteins beyond AHL and interkingdom signaling. Based on gene context and the conservation levels of invariant amino acids of ABD, we have classified LuxR solos into functionally meaningful groups or putative orthologs. Surprisingly, putative LuxR solos were also found in a few non-proteobacterial genomes which are not known to carry AHL-QS systems. Multiple predicted LuxR solos in the same genome appeared to have different levels of conservation of invariant amino acid residues of ABD questioning their binding to AHLs. In summary, this study provides a detailed overview of distribution of LuxR solos and their probable roles in bacteria with genome sequence information. PMID:25759807

  5. Streptosporangium sonchi sp. nov. and Streptosporangium kronopolitis sp. nov., two novel actinobacteria isolated from a root of common sowthistle (Sonchus oleraceus L.) and a millipede (Kronopolites svenhedind Verhoeff).

    PubMed

    Ma, Zhaoxu; Liu, Hui; Liu, Chongxi; He, Hairong; Zhao, Junwei; Wang, Xin; Li, Jiansong; Wang, Xiangjing; Xiang, Wensheng

    2015-06-01

    Two novel actinobacteria, designated strains NEAU-QS7(T) and NEAU-ML10(T), were isolated from a root of Sonchus oleraceus L. and a Kronopolites svenhedind Verhoeff specimen, respectively, collected from Wuchang, Heilongjiang Province, China. A polyphasic study was carried out to establish the taxonomic positions of these strains. The two strains were observed to form abundant aerial hyphae that differentiated into spherical spore vesicles. The phylogenetic analysis based on the 16S rRNA gene sequences of strains NEAU-QS7(T) and NEAU-ML10(T) showed that the two novel isolates exhibited 99.7 % 16S rRNA gene sequence similarity with each other and that they are most closely related to Streptosporangium shengliense NEAU-GH7(T) (99.1, 99.0 %) and Streptosporangium longisporum DSM 43180(T) (99.1, 99.0 %). However, the DNA-DNA hybridization value between strains NEAU-QS7(T) and NEAU-ML10(T) was 46.5 %, and the values between the two strains and their closest phylogenetic relatives were also below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA-DNA hybridization results, the two strains can be distinguished from each other and their closest phylogenetic relatives. Thus, strains NEAU-QS7(T) and NEAU-ML10(T) represent two novel species of the genus Streptosporangium, for which the names Streptosporangium sonchi sp. nov. and Streptosporangium kronopolitis sp. nov. are proposed. The type strains are NEAU-QS7(T) (=CGMCC 4.7142(T) =DSM 46717(T)) and NEAU-ML10(T) (=CGMCC 4.7153(T) =DSM 46720(T)), respectively.

  6. Rapid Assessment of the Role of Microstructural Variability in the Fatigue Behavior of Structural Alloys using Ultrasonic Fatigue

    DTIC Science & Technology

    2007-06-23

    6 %AI-2%Sn- 4 %Zr- 6 %Mo in the very high cycle regime. The microstructure is a two-phase structure with primary a grains (ap grains) in a transformed [3...aluminum [2], magnesium [3], nickel-based [ 4 ], and titanium [5,6] alloy systems. Fatigue crack initiation is known to consume the majority of fatigue...microstructural neighborhood affects this process. In fatigue studies of alpha + beta titanium alloys, [ 6 -9] cyclic deformation localization is first observed in

  7. Lunar base and Mars base design projects

    NASA Technical Reports Server (NTRS)

    Amos, J.; Campbell, J.; Hudson, C.; Kenny, E.; Markward, D.; Pham, C.; Wolf, C.

    1989-01-01

    The space design classes at the University of Texas at Austin undertook seven projects in support of the NASA/USRA advanced space design program during the 1988-89 year. A total of 51 students, including 5 graduate students, participated in the design efforts. Four projects were done within the Aerospace Engineering (ASE) design program and three within the Mechanical Engineering (ME) program. Both lunar base and Mars base design efforts were studied, and the specific projects were as follows: Lunar Crew Emergency Rescue Vehicle (ASE); Mars Logistics Lander Convertible to a Rocket Hopper (ME); A Robotically Constructed Production and Supply Base on Phobos (ASE); A Mars/Phobos Transportation System (ASE); Manned Base Design and Related Construction Issues for Mars/Phobos Mission (ME); and Health Care Needs for a Lunar Colony and Design of Permanent Medical Facility (ME).

  8. Logistics: Supply Based or Distribution Based?

    DTIC Science & Technology

    2007-04-01

    supply chain management, the need to adapt systems as conditions and capabilities change may not be clear or the root causes of problems may not be...logistics-system and supply - chain design and management positions. They need to become adept at integrating the full range of options available to...distribution-based and supply-based designs, the Army, in conjunction with its joint supply - chain partners, should seek optimal, balanced logistics system designs that it can adapt quickly to changing conditions.

  9. Carbon Based Nanotechnology: Review

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash (Technical Monitor)

    1999-01-01

    This presentation reviews publicly available information related to carbon based nanotechnology. Topics covered include nanomechanics, carbon based electronics, nanodevice/materials applications, nanotube motors, nano-lithography and H2O storage in nanotubes.

  10. Centrality based Document Ranking

    DTIC Science & Technology

    2014-11-01

    approach. We model the documents to be ranked as nodes in a graph and place edges between documents based on their similarity. Given a query, we compute...similarity of the query with respect to every document in the graph . Based on these similarity values, documents are ranked for a given query...clinical documents using centrality based approach. We model the documents to be ranked as nodes in a graph and place edges between documents based on their

  11. Stolen Base Physics

    NASA Astrophysics Data System (ADS)

    Kagan, David

    2013-05-01

    Few plays in baseball are as consistently close and exciting as the stolen base. While there are several studies of sprinting,2-4 the art of base stealing is much more nuanced. This article describes the motion of the base-stealing runner using a very basic kinematic model. The model will be compared to some data from a Major League game. The predictions of the model show consistency with the skills needed for effective base stealing.

  12. Cooperative Knowledge Bases.

    DTIC Science & Technology

    1988-02-01

    intellegent knowledge bases. The present state of our system for concurrent evaluation of a knowledge base of logic clauses using static allocation...de Kleer, J., An assumption-based TMS, Artificial Intelligence, Vol. 28, No. 2, 1986. [Doyle 79) Doyle, J. A truth maintenance system, Artificial

  13. Stolen Base Physics

    ERIC Educational Resources Information Center

    Kagan, David

    2013-01-01

    Few plays in baseball are as consistently close and exciting as the stolen base. While there are several studies of sprinting, the art of base stealing is much more nuanced. This article describes the motion of the base-stealing runner using a very basic kinematic model. The model will be compared to some data from a Major League game. The…

  14. Community-based Education.

    ERIC Educational Resources Information Center

    Villani, Christine J.; Atkins, Douglas

    2000-01-01

    Based on work by Howard Gardner and James Comer, this article discusses the importance of creating and maintaining community-based relationships as part of community-based education. Students go beyond basic core academics and develop values and the freedom to uncover and resolve community problems or concerns. (MLH)

  15. Permanent sequelae in sports injuries: a population based study

    PubMed Central

    Marchi, A.; Di, B; Messi, G.; Gazzola, G.

    1999-01-01

    AIM—To identify permanent sequelae after sports injuries in children and adolescents.
METHODS—In 1985, a prospective register was drawn up of all sports related injuries reported that year by the residents of Trieste, Italy aged 6-15 years. Moderate to severe injuries (scoring ⩾ 2 on the abbreviated injury scale (AIS)) were the object of a longitudinal clinical study. In 1988, 30.9% of the 220 subjects enrolled had sequelae. A further follow up was undertaken in 1997.
RESULTS—The follow up in 1997 involved 54 subjects (26 girls; average age 24.5 years). Subjective and objective sequelae, by now considered to be permanent, were found in 61.1%, corresponding to 15% of the AIS ⩾ 2 injuries recorded in 1985. The prevalence of sequelae was similar in the two sexes, in relation to the child's age at time of injury, and in the different sports practised. It was higher in relation to the severity of the lesion (89% of AIS 3injuries examined, 56% of AIS 2 injuries) and to the type of lesion and its location. With regard to AIS ⩾ 2 injuries, permanent sequelae were found in 50% of ankle fractures, 43% of elbow fractures, 33% of leg/foot fractures, 25% of knee sprains, and 23% of ankle sprains.
CONCLUSIONS—The frequency of sequelae in sports injuries in children and adolescents is high. The risk appears to be connected to certain anatomical and functional age characteristics. Prevention strategies should include specific assessment of physical fitness and adequate follow up after the accident, particularly rehabilitation.

 PMID:10490437

  16. 50 CFR 660.140 - Shorebased IFQ Program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... On or about January 1 each year, QS permit owners will be notified, via the IFQ Web site and their QS... be notified of QP deposits via the IFQ Web site and their QS account. QP and IBQ pounds will be... Web site, the QS permit owner must enter pertinent information regarding the transfer...

  17. Saturn base heating handbook

    NASA Technical Reports Server (NTRS)

    Mullen, C. R.; Bender, R. L.; Bevill, R. L.; Reardon, J.; Hartley, L.

    1972-01-01

    A handbook containing a summary of model and flight test base heating data from the S-1, S-1B, S-4, S-1C, and S-2 stages is presented. A review of the available prediction methods is included. Experimental data are provided to make the handbook a single source of Saturn base heating data which can be used for preliminary base heating design predictions of launch vehicles.

  18. Exploitation of Unintentional Information Leakage from Integrated Circuits

    DTIC Science & Technology

    2011-12-01

    variations in computation time —the effect of which is to leak information about the value of the key. Kocher’s attack is based on analysis of 156 this...intrusive analysis of smart-cards based on electro-magnetic emissions, the SEMA and DEMA methods . Rump session of Eurocrypt, 2000. QS01. Jean-Jacques...22 2.5 Techniques . . . . . . . . . . . . . . . . . . . . . . . . 24 2.5.1 Timing Analysis . . . . . . . . . . . . . . . . . 25 2.5.2

  19. Gasification-based biomass

    SciTech Connect

    None, None

    2009-01-18

    The gasification-based biomass section of the Renewable Energy Technology Characterizations describes the technical and economic status of this emerging renewable energy option for electricity supply.

  20. XML-BASED REPRESENTATION

    SciTech Connect

    R. KELSEY

    2001-02-01

    For focused applications with limited user and use application communities, XML can be the right choice for representation. It is easy to use, maintain, and extend and enjoys wide support in commercial and research sectors. When the knowledge and information to be represented is object-based and use of that knowledge and information is a high priority, then XML-based representation should be considered. This paper discusses some of the issues involved in using XML-based representation and presents an example application that successfully uses an XML-based representation.

  1. Soy-based polyols

    DOEpatents

    Suppes, Galen; Lozada, Zueica; Lubguban, Arnold

    2013-06-25

    The invention provides processes for preparing soy-based oligomeric polyols or substituted oligomeric polyols, as well as urethane bioelasteromers comprising the oligomeric polyols or substituted oligomeric polyols.

  2. Medical Knowledge Bases.

    ERIC Educational Resources Information Center

    Miller, Randolph A.; Giuse, Nunzia B.

    1991-01-01

    Few commonly available, successful computer-based tools exist in medical informatics. Faculty expertise can be included in computer-based medical information systems. Computers allow dynamic recombination of knowledge to answer questions unanswerable with print textbooks. Such systems can also create stronger ties between academic and clinical…

  3. Zero-Based Budgeting.

    ERIC Educational Resources Information Center

    Wichowski, Chester

    1979-01-01

    The zero-based budgeting approach is designed to achieve the greatest benefit with the fewest undesirable consequences. Seven basic steps make up the zero-based decision-making process: (1) identifying program goals, (2) classifying goals, (3) identifying resources, (4) reviewing consequences, (5) developing decision packages, (6) implementing a…

  4. Content-Based Instruction.

    ERIC Educational Resources Information Center

    CATESOL Journal, 1992

    1992-01-01

    This English-as-a-Second Language (ESL) journal periodical devotes entire issues to specific issues. The theme of this issue is "Content-Base Instruction." Articles include: "Syllabus Design in Content-Based Instruction" (David E. Eskey); "How Relevant Is Relevance?: An Examination of Student Needs, Interests, and…

  5. Content-Based Instruction

    ERIC Educational Resources Information Center

    DelliCarpini, M.; Alonso, O.

    2013-01-01

    DelliCarpini and Alonso's book "Content-Based Instruction" explores different approaches to teaching content-based instruction (CBI) in the English language classroom. They provide a comprehensive overview of how to teach CBI in an easy-to-follow guide that language teachers will find very practical for their own contexts. Topics…

  6. Red-based cumulus.

    PubMed

    Gedzelman, Stanley David

    2015-02-01

    Observations and model simulations of cumulus clouds whose bases are tinted red when the Sun is well above the horizon are presented. Conditions for seeing red bases include (1) a red underlying surface (which may consist of dust clouds, as from haboobs) with high albedo, (2) small fractional cloud cover when the Sun is far enough below the zenith for direct sunlight to illuminate much of the surface directly below and around cloud base, (3) optically thick clouds so that the bases are dark, and (4) clouds with bases that are near enough to the observer to appear high in the sky so that the admixture of scattered light from the intervening atmosphere is minimized.

  7. Base Flow Model Validation

    NASA Technical Reports Server (NTRS)

    Sinha, Neeraj; Brinckman, Kevin; Jansen, Bernard; Seiner, John

    2011-01-01

    A method was developed of obtaining propulsive base flow data in both hot and cold jet environments, at Mach numbers and altitude of relevance to NASA launcher designs. The base flow data was used to perform computational fluid dynamics (CFD) turbulence model assessments of base flow predictive capabilities in order to provide increased confidence in base thermal and pressure load predictions obtained from computational modeling efforts. Predictive CFD analyses were used in the design of the experiments, available propulsive models were used to reduce program costs and increase success, and a wind tunnel facility was used. The data obtained allowed assessment of CFD/turbulence models in a complex flow environment, working within a building-block procedure to validation, where cold, non-reacting test data was first used for validation, followed by more complex reacting base flow validation.

  8. Yeast Based Sensors

    NASA Astrophysics Data System (ADS)

    Shimomura-Shimizu, Mifumi; Karube, Isao

    Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of yeast based sensors have been developed as analytical tools. Yeasts are known as facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic conditions. The yeast based sensor consisted of a DO electrode and an immobilized omnivorous yeast. In yeast based sensor development, many kinds of yeast have been employed by applying their characteristics to adapt to the analyte. For example, Trichosporon cutaneum was used to estimate organic pollution in industrial wastewater. Yeast based sensors are suitable for online control of biochemical processes and for environmental monitoring. In this review, principles and applications of yeast based sensors are summarized.

  9. Data base management study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Data base management techniques and applicable equipment are described. Recommendations which will assist potential NASA data users in selecting and using appropriate data base management tools and techniques are presented. Classes of currently available data processing equipment ranging from basic terminals to large minicomputer systems were surveyed as they apply to the needs of potential SEASAT data users. Cost and capabilities projections for this equipment through 1985 were presented. A test of a typical data base management system was described, as well as the results of this test and recommendations to assist potential users in determining when such a system is appropriate for their needs. The representative system tested was UNIVAC's DMS 1100.

  10. Skull Base Anatomy.

    PubMed

    Patel, Chirag R; Fernandez-Miranda, Juan C; Wang, Wei-Hsin; Wang, Eric W

    2016-02-01

    The anatomy of the skull base is complex with multiple neurovascular structures in a small space. Understanding all of the intricate relationships begins with understanding the anatomy of the sphenoid bone. The cavernous sinus contains the carotid artery and some of its branches; cranial nerves III, IV, VI, and V1; and transmits venous blood from multiple sources. The anterior skull base extends to the frontal sinus and is important to understand for sinus surgery and sinonasal malignancies. The clivus protects the brainstem and posterior cranial fossa. A thorough appreciation of the anatomy of these various areas allows for endoscopic endonasal approaches to the skull base.

  11. Effects of age on searching for and enumerating targets that cannot be detected efficiently.

    PubMed

    Watson, Derrick G; Maylor, Elizabeth A; Bruce, Lucy A M

    2005-08-01

    We investigated the effects of old age on search, subitizing, and counting of difficult-to-find targets. In Experiment 1, young and older adults enumerated targets (Os) with and without distractors (Qs). Without distractors, the usual subitization-counting function occurred in both groups, with the same subitization span of 3.3 items. Subitization disappeared with distractors; older adults were slowed more overall by their presence but enumeration rates were not slowed by ageing either with or without distractors. In contrast, search rates for a single target (O among Qs) were twice as slow for older as for young adults. Experiment 2 tested and ruled out one account of age-equivalent serial enumeration based on the need to subvocalize numbers as items are enumerated. Alternative explanations based on the specific task differences between detecting and enumerating stimuli are discussed.

  12. Community-Based Care

    MedlinePlus

    ... providing important healthcare or personal care support. Adult Day Care Adult day care is a community-based option that has become ... support services in a group setting. Most adult day care centers are either in churches or community centers. ...

  13. Graphene-based composites.

    PubMed

    Huang, Xiao; Qi, Xiaoying; Boey, Freddy; Zhang, Hua

    2012-01-21

    Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

  14. Evidence-based neurosurgery

    PubMed Central

    Esene, Ignatius N.; Baeesa, Saleh S.; Ammar, Ahmed

    2016-01-01

    Medical evidence is obtainable from approaches, which might be descriptive, analytic and integrative and ranked into levels of evidence, graded according to quality and summarized into strengths of recommendation. Sources of evidence range from expert opinions through well-randomized control trials to meta-analyses. The conscientious, explicit, and judicious use of current best evidence in making decisions related to the care of individual patients defines the concept of evidence-based neurosurgery (EBN). We reviewed reference books of clinical epidemiology, evidence-based practice and other previously related articles addressing principles of evidence-based practice in neurosurgery. Based on existing theories and models and our cumulative years of experience and expertise conducting research and promoting EBN, we have synthesized and presented a holistic overview of the concept of EBN. We have also underscored the importance of clinical research and its relationship to EBN. Useful electronic resources are provided. The concept of critical appraisal is introduced. PMID:27356649

  15. COMMUNITY BASED ENVIRONMENTAL PROTECTION

    EPA Science Inventory

    Community Based Environmental Protection intends to make environmental protection spring from the needs and values of the community of interest. Real community involvement in protecting the environment requires a process in which the environmental needs of communities and ecosyst...

  16. Benzimidazole Based Aerogel Materials

    NASA Technical Reports Server (NTRS)

    Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

    2016-01-01

    The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

  17. Transformation based endorsement systems

    NASA Technical Reports Server (NTRS)

    Sudkamp, Thomas

    1988-01-01

    Evidential reasoning techniques classically represent support for a hypothesis by a numeric value or an evidential interval. The combination of support is performed by an arithmetic rule which often requires restrictions to be placed on the set of possibilities. These assumptions usually require the hypotheses to be exhausitive and mutually exclusive. Endorsement based classification systems represent support for the alternatives symbolically rather than numerically. A framework for constructing endorsement systems is presented in which transformations are defined to generate and update the knowledge base. The interaction of the knowledge base and transformations produces a non-monotonic reasoning system. Two endorsement based reasoning systems are presented to demonstrate the flexibility of the transformational approach for reasoning with ambiguous and inconsistent information.

  18. Defining Empirically Based Practice.

    ERIC Educational Resources Information Center

    Siegel, Deborah H.

    1984-01-01

    Provides a definition of empirically based practice, both conceptually and operationally. Describes a study of how research and practice were integrated in the graduate social work program at the School of Social Service Administration, University of Chicago. (JAC)

  19. Microstereolithography for polymer-based based MEMS

    NASA Astrophysics Data System (ADS)

    Varadan, Vijay K.; Xie, Jining

    2003-07-01

    Microfabrication techniques such as bulk micromachining and surface micromachining currently employed to conceive MEMS are largely derived from the standard IC and microelectronics technology. Even though many MEMS devices with integrated electronics have been achieved by using the traditional micromachining techniques, some limitations have nevertheless to be underlined: 1) these techniques are very expensive and need specific installations as well as a cleanroom environment, 2) the materials that can be used up to now are restricted to silicon and metals, 3) the manufacture of 3D parts having curved surfaces or an important number of layers is not possible. Moreover, for some biological applications, the materials used for sensors must be compatible with human body and the actuators need to have high strain and displacement which the current silicon based MEMS do not provide. It is thus natural for the researchers to 'look' for alternative methods such as Microstereolithography (MSL) to make 3D sensors and actuators using polymeric based materials. For MSL techniques to be successful as their silicon counterparts, one has to come up with multifunctional polymers with electrical properties comparable to silicon. These multifunctional polymers should not only have a high sensing capability but also a high strain and actuation performance. A novel UV-curable polymer uniformly bonded with functionalized nanotubes was synthesized via a modified three-step in-situ polymerization. Purified multi-walled nanotubes, gained from the microwave chemical vapor deposition method, were functionalized by oxidation. The UV curable polymer was prepared from toluene diisocyanate (TDI), functionalized nanotubes, and 2-hydroxyethyl methacrylate (HEMA). The chemical bonds between -NCO groups of TDI and -OH, -COOH groups of functionalized nanotubes help for conceiving polymeric based MEMS devices. A cost effective fabrication techniques was presented using Micro Stereo Lithography and

  20. Information Based Numerical Practice.

    DTIC Science & Technology

    1987-02-01

    N I IIi I2 LA 1.6 liii I~JIIN MARYLAND COLLEGE PARK CAMPUS INSTITUTE FOR PHYSICAL SCIENCE AND TECHNOLOGY Technical Note S1-1059 INFORMATION BASED...K-0169 9. PERFORMING ORGANIZATION NMEU AMC ADDRESS 16. PROGRAM CELEMNT. PROJECT. TASK AREA & WORK UNIT NUNSERS, Institute for Physical Science and...BASED NUMERICAL PRACTICE I. Babuska Institute for Physical Science and Technology University of Maryland, College Park, MD 20740 a Partially supported by

  1. Layered nickel based superconductors

    SciTech Connect

    Ronning, Filip; Bauer, Eric D; Park, Tuson; Kurita, Nobuyuki; Klimczuk, T; Movshovich, R; Thompson, J D; Sefat, A S; Mandrus, D

    2009-01-01

    We review the properties of Ni-based superconductors which contain Ni{sub 2}X{sub 2} (X=As, P, Bi, Si, Ge, B) planes, a common structural element to the recently discovered FeAs superconductors. We also compare the properties ofthe Ni-and Fe-based systems from a perspective ofelectronic structure as well as structure-property relations.

  2. Agent Based Computing Machine

    DTIC Science & Technology

    2005-12-09

    coordinates as in cellular automata systems. But using biology as a model suggests that the most general systems must provide for partial, but constrained...17. SECURITY CLASSIFICATION OF 118. SECURITY CLASSIFICATION OF 19. SECURITY CLASSIFICATION OF 20. LIMITATION OF ABSTRA REPORT THIS PAGE ABSTRACT...system called an "agent based computing" machine (ABC Machine). The ABC Machine is motivated by cellular biochemistry and it is based upon a concept

  3. New formaldehyde base disinfectants.

    NASA Technical Reports Server (NTRS)

    Trujillo, R.; Lindell, K. F.

    1973-01-01

    Preparations of formaldehyde in various organic liquids - ethylene glycol, glycerol, and propylene glycol - serve as effective disinfectants towards microbial vegetative cells and spores. This disinfection is a temperature-dependent process and is manifest when these formaldehyde base disinfectants are dissolved in water. The irritating vapors associated with formaldehyde disinfection are not present in either of these new formaldehyde base disinfectants or in aqueous solutions of them.

  4. LDEF materials data bases

    NASA Technical Reports Server (NTRS)

    Funk, Joan G.; Strickland, John W.; Davis, John M.

    1993-01-01

    The Long Duration Exposure Facility (LDEF) and the accompanying experiments were composed of and contained a wide variety of materials representing the largest collection of materials flown in low Earth orbit (LEO) and retrieved for ground based analysis to date. The results and implications of the mechanical, thermal, optical, and electrical data from these materials are the foundation on which future LEO space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been charged with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the spacecraft user community in an easily accessed, user-friendly form. This paper discusses the format and content of the three data bases developed or being developed to accomplish this task. The hardware and software requirements for each of these three data bases are discussed along with current availability of the data bases. This paper also serves as a user's guide to the MAPTIS LDEF Materials Data Base.

  5. Relational data bank for Burroughs computers

    NASA Astrophysics Data System (ADS)

    Guerra, P. C. P.; Alexandre, J. O. M.; Deoliveira, O. M.; Velasco, F. R. D.; Derenna-Souza, C.

    1981-06-01

    The RELATIONAL SYSTEM's languages designed for Burroughs' machines (series B7000/B6000) are introduced. The RELATIONAL SYSTEM was conceived to implement multipurpose relational data bases in the Burroughs' environment, using the DBMS software package, DMS-II, as a support tool. It offers to users a high-level nonprocedural query language, called SEQUEL2/QS, and usual languages as COBOL, ALGOL, and PL/I.

  6. S&MA Requirements Tool (SMART)

    NASA Technical Reports Server (NTRS)

    Kulpa, Vyga

    2004-01-01

    In FY03 QS10 began building an S&MA web based data management tool,"Safety & Mission Assurance Requirements Tool" (SMART) that identifies S&MA requirements, tailors requirements to IAW project/program categories, tracks implementation, and provides a template for developing requirements and tracking waivers. This report provides a SMART process flow, typical application, typical data requirement deliverables, progress in 03, and FY04 activities.

  7. Combining Modis and Quikscat Data to Delineate Surface and Near-Surface Melt on the Greenland Ice Sheet

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Nghiem, Son V.; DiGirolamo, Nicolo E.; Neumann, Gregory

    2010-01-01

    Over the last two decades, increasing melt has been measured on the Greenland Ice Sheet, along with mass loss as determined from satellite data, Monitoring the state of the Greenland Ice Sheet becomes critical especially because it is actively losing mass, and the ice sheet has a sea-level rise potential of 7 in. However measurement of the extent of surface melt varies depending on the sensor used, whether it is passive or active microwave or visible or thermal infrared. We have used remote-sensing data products to study surface and near-surface melt characteristics of the Greenland Ice Sheet. We present a blended MODIS-QS melt daily product for 2007 [1]. The products, including Moderate Resolution Imaging Spectroradiometer (MODIS) daily land-surface temperature (LST) and a special daily melt product derived from the QuikSCAT (QS) scatterometer [2,3] show consistency in delineating the melt boundaries on a daily basis in the 2007 melt season [I], though some differences are identified. An assessment of maximum melt area for the 2007 melt shows that the QSCAT product detects a greater amount of melt (862,769 square kilometers) than is detected by the MODIS LST product (766,184 square kilometers). The discrepancy is largely because the QS product can detect both surface and near-surface melt and the QS product captures melt if it occurred anytime during the day while the MODIS product is obtained from a point in time on a given day. However on a daily bases, other factors influence the measurement of melt extent. In this work we employ the digital-elevation model of Bamber et al. [4] along with the National Centers for Environmental Prediction (NCEP) data to study some areas and time periods in detail during the 2007 melt season. We focus on times in which the QS and MODIS LST products do not agree exactly. We use NCEP and elevation data to analyze the atmospheric factors forcing the melt process, to gain an improved understanding of the conditions that lead to melt

  8. [Evidence-based medicine].

    PubMed

    Saad, E D; Grunspun, H

    1996-01-01

    Evidence-based medicine has been described as a new approach to teaching and practicing clinical medicine. Although the search for evidence is an established practice among physicians, what is being proposed is the systematic gathering and critical interpretation of data, which can then be used in the appropriate context. The main objective is to provide better care for patients. This is accomplished by transforming clinical problems in specific questions to be answered by searching the literature for the levels of evidence favoring the possible interventions for one particular case. This has to be done in a systematic and conscientious fashion. Through its method, evidence-based medicine places less value on clinical experience, the study understanding of pathophysiology, and common sense; instead, it emphasizes observation, levels of evidence, and critical interpretation of original literature. In this manner, evidence-based medicine may be seen by the authoritarian physician as a threat. Other obstacles to the acceptance of the method include lack of time and lack of familiarity with computers. One important limitation of evidence-based medicine is the incomplete or contradictory evidence available in many areas of clinical medicine, or the so-called "grey zones". We outline the main aspects of evidence-based medicine, expecting a growing interest among brazilian physicians for this useful clinical tool.

  9. SAR based adaptive GMTI

    NASA Astrophysics Data System (ADS)

    Vu, Duc; Guo, Bin; Xu, Luzhou; Li, Jian

    2010-04-01

    We consider ground moving target indication (GMTI) and target velocity estimation based on multi-channel synthetic aperture radar (SAR) images. Via forming velocity versus cross-range images, we show that small moving targets can be detected even in the presence of strong stationary ground clutter. Moreover, the velocities of the moving targets can be estimated, and the misplaced moving targets can be placed back to their original locations based on the estimated velocities. Adaptive beamforming techniques, including Capon and generalizedlikelihood ratio test (GLRT), are used to form velocity versus cross-range images for each range bin of interest. The velocity estimation ambiguities caused by the multi-channel array geometry are analyzed. We also demonstrate the effectiveness of our approaches using the Air Force Research Laboratory (AFRL) publicly-released Gotcha SAR based GMTI data set.

  10. Model based manipulator control

    NASA Technical Reports Server (NTRS)

    Petrosky, Lyman J.; Oppenheim, Irving J.

    1989-01-01

    The feasibility of using model based control (MBC) for robotic manipulators was investigated. A double inverted pendulum system was constructed as the experimental system for a general study of dynamically stable manipulation. The original interest in dynamically stable systems was driven by the objective of high vertical reach (balancing), and the planning of inertially favorable trajectories for force and payload demands. The model-based control approach is described and the results of experimental tests are summarized. Results directly demonstrate that MBC can provide stable control at all speeds of operation and support operations requiring dynamic stability such as balancing. The application of MBC to systems with flexible links is also discussed.

  11. Protein based Block Copolymers

    PubMed Central

    Rabotyagova, Olena S.; Cebe, Peggy; Kaplan, David L.

    2011-01-01

    Advances in genetic engineering have led to the synthesis of protein-based block copolymers with control of chemistry and molecular weight, resulting in unique physical and biological properties. The benefits from incorporating peptide blocks into copolymer designs arise from the fundamental properties of proteins to adopt ordered conformations and to undergo self-assembly, providing control over structure formation at various length scales when compared to conventional block copolymers. This review covers the synthesis, structure, assembly, properties, and applications of protein-based block copolymers. PMID:21235251

  12. Lidar base specification

    USGS Publications Warehouse

    Heidemann, Hans Karl.

    2012-01-01

    Lidar is a fast evolving technology, and much has changed in the industry since the final draft of the “Lidar Base Specification Version 1.0” was written. Lidar data have improved in accuracy and spatial resolution, geospatial accuracy standards have been revised by the American Society for Photogrammetry and Remote Sensing (ASPRS), industry standard file formats have been expanded, additional applications for lidar have become accepted, and the need for interoperable data across collections has been realized. This revision to the “Lidar Base Specification Version 1.0” publication addresses those changes and provides continued guidance towards a nationally consistent lidar dataset.

  13. Intracranial dural based chondroma.

    PubMed

    Reinshagen, Clemens; Redjal, Navid; Sajed, Dipti P; Nahed, Brian V; Walcott, Brian P

    2016-03-01

    Intracranial chondromas are benign, slow-growing, cartilaginous tumors, which comprise only about 0.2% of all intracranial tumors. The majority of these lesions occur at the base of the skull, where they are thought to arise from residual embryonic chondrogenic cells along the basal synchondrosis. Very rarely, they may also originate from the convexity dura, falx cerebri, or the brain parenchyma. We present a patient with a dural based chondroma to highlight the technical considerations of surgical resection. The recent literature on intracranial chondromas regarding incidence, pathophysiologic origin, clinical symptoms, imaging, histopathology and prognosis is reviewed.

  14. Zero-Base Budgeting.

    ERIC Educational Resources Information Center

    Yagielski, John

    In outline form, this document presents basic information on the school district, the reasons the district considered zero-base budgeting (ZBB), the formation and membership of the advisory School Cost Analysis Team, the district's investigation of the ZBB concept, an overview of the ways the district used the ZBB process, the identification of…

  15. Problem-Based Learning

    ERIC Educational Resources Information Center

    Allen, Deborah E.; Donham, Richard S.; Bernhardt, Stephen A.

    2011-01-01

    In problem-based learning (PBL), students working in collaborative groups learn by resolving complex, realistic problems under the guidance of faculty. There is some evidence of PBL effectiveness in medical school settings where it began, and there are numerous accounts of PBL implementation in various undergraduate contexts, replete with…

  16. Orff-Based Improvisation.

    ERIC Educational Resources Information Center

    Thomas, Judith

    1980-01-01

    Described are improvisational activities based on the Orff-Schulwerk teaching technique which include: sound and movement; sound and movement plus visuals; interpretation of designs from nature, architecture, paintings, rotating rondo, singing hands, and moving from words to song. Pictures of children participating in these activities are…

  17. Team Based Work. Symposium.

    ERIC Educational Resources Information Center

    2002

    This document contains three papers from a symposium on team-based work in human resource development (HRD). "Toward Transformational Learning in Organizations: Effects of Model-II Governing Variables on Perceived Learning in Teams" (Blair K. Carruth) summarizes a study that indicated that, regardless of which Model-II variable (valid…

  18. Gasification at Navy Bases.

    DTIC Science & Technology

    1978-07-01

    Battalion Center at Port Hueneme, CA. The title of the contract was ’ Coal Gasification Feasibility Study.’ Coal gasification is recognized as a way...operated. A conceptual design study comparing coal gasification with central direct coal-fired boilers at five bases was performed.

  19. Polymer based tunneling sensor

    NASA Technical Reports Server (NTRS)

    Cui, Tianhong (Inventor); Wang, Jing (Inventor); Zhao, Yongjun (Inventor)

    2006-01-01

    A process for fabricating a polymer based circuit by the following steps. A mold of a design is formed through a lithography process. The design is transferred to a polymer substrate through a hot embossing process. A metal layer is then deposited over at least part of said design and at least one electrical lead is connected to said metal layer.

  20. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  1. Lunar Base Sitting

    NASA Astrophysics Data System (ADS)

    Staehle, Robert L.; Burke, James D.; Snyder, Gerald C.; Dowling, Richard; Spudis, Paul D.

    1993-12-01

    Speculation with regard to a permanent lunar base has been with us since Robert Goddard was working on the first liquid-fueled rockets in the 1920's. With the infusion of data from the Apollo Moon flights, a once speculative area of space exploration has become an exciting possibility. A Moon base is not only a very real possibility, but is probably a critical element in the continuation of our piloted space program. This article, originally drafted by World Space Foundation volunteers in conjuction with various academic and research groups, examines some of the strategies involved in selecting an appropriate site for such a lunar base. Site selection involves a number of complex variables, including raw materials for possible rocket propellant generation, hot an cold cycles, view of the sky (for astronomical considerations, among others), geological makeup of the region, and more. This article summarizes the key base siting considerations and suggests some alternatives. Availability of specific resources, including energy and certain minerals, is critical to success.

  2. Lunar Base Sitting

    NASA Technical Reports Server (NTRS)

    Staehle, Robert L.; Burke, James D.; Snyder, Gerald C.; Dowling, Richard; Spudis, Paul D.

    1993-01-01

    Speculation with regard to a permanent lunar base has been with us since Robert Goddard was working on the first liquid-fueled rockets in the 1920's. With the infusion of data from the Apollo Moon flights, a once speculative area of space exploration has become an exciting possibility. A Moon base is not only a very real possibility, but is probably a critical element in the continuation of our piloted space program. This article, originally drafted by World Space Foundation volunteers in conjuction with various academic and research groups, examines some of the strategies involved in selecting an appropriate site for such a lunar base. Site selection involves a number of complex variables, including raw materials for possible rocket propellant generation, hot an cold cycles, view of the sky (for astronomical considerations, among others), geological makeup of the region, and more. This article summarizes the key base siting considerations and suggests some alternatives. Availability of specific resources, including energy and certain minerals, is critical to success.

  3. WATERSHED BASED SURVEY DESIGNS

    EPA Science Inventory

    The development of watershed-based design and assessment tools will help to serve the multiple goals for water quality monitoring required under the Clean Water Act, including assessment of regional condition to meet Section 305(b), identification of impaired water bodies or wate...

  4. Developing Mobile Based Instruction

    ERIC Educational Resources Information Center

    Martin, Florence; Pastore, Raymond; Snider, Jean

    2012-01-01

    This paper describes an instructional design class's experience developing instruction for the mobile web. The class was taught at a southeastern university in the United States in a master's level computer based instruction course. Two example projects are showcased and student reflections on design issues are highlighted. Additionally,…

  5. Aptamer-based nanobiosensors.

    PubMed

    Kim, Yeon Seok; Raston, Nurul Hanun Ahmad; Gu, Man Bock

    2016-02-15

    It has been more than two decades since aptamer and the systematic evolution of ligands by exponential enrichment (SELEX) method were discovered by Larry Gold and Andrew Ellington in 1990, respectively. Based on the various advantages of aptamers, they have become a potent rival of antibodies in therapeutics and bio-analysis. Especially, the recent advances in aptamer biosensor application are remarkable due to its intrinsic properties of aptamers as nucleic acids and target induced conformational changes, in addition to the introduction of graphene oxide-based easy and simple immobilization-free screening method even for dual aptamers. In addition, the incorporation of various nanomaterials such as metallic nanoparticles, carbon materials, and functional nanospheres in aptasensors has facilitated the improvement of analytical performance and commercial application of aptasensors. In this review, recent prominent reports on aptasensors utilizing nanomaterials were introduced to understand the principle of aptamer-based biosensors and provide an insight for new strategies of aptasensors and the application of various nanomaterials. The perspective on aptamer-based biosensors and diagnostics was also discussed in view of technology and market.

  6. School Based Health Centers

    ERIC Educational Resources Information Center

    Children's Aid Society, 2012

    2012-01-01

    School Based Health Centers (SBHC) are considered by experts as one of the most effective and efficient ways to provide preventive health care to children. Few programs are as successful in delivering health care to children at no cost to the patient, and where they are: in school. For many underserved children, The Children's Aid Society's…

  7. Shock wave data base

    NASA Astrophysics Data System (ADS)

    Levashov, P. R.; Fortov, V. E.; Khishchenko, K. V.; Lomov, I. N.; Lomonosov, I. V.

    1998-07-01

    The information on thermodynamic properties of matter under conditions of extremely high pressure and temperature is collected and treated. About 10000 experimental points are stored into ASCII files and converted into SQL format. Relational SQL data base is installed on server and graphical interface is elaborated. The information can be accessed via Internet with the help of Netscape Navigator 3.0 browser.

  8. Project-Based Science

    ERIC Educational Resources Information Center

    Krajcik, Joe

    2015-01-01

    Project-based science is an exciting way to teach science that aligns with the "Next Generation Science Standards" ("NGSS"). By focusing on core ideas along with practices and crosscutting concepts, classrooms become learning environments where teachers and students engage in science by designing and carrying out…

  9. Space based OTV servicing

    NASA Technical Reports Server (NTRS)

    Mcallister, J. G.

    1984-01-01

    Space based servicing of an orbit transfer vehicle (OTV) was previously outlined in sufficient detail to arrive at OTV and support system servicing requirements. Needed space station facilities and their functional requirements were identified. The impact of logistics and space serviceable design on the OTV design is detailed herein. RL10 derivative rocket engine inspection task times are enumerated.

  10. Zero-Base Budgeting.

    ERIC Educational Resources Information Center

    Harvey, L. James

    The concept of Zero-Base Budgeting (ZBB) is discussed in terms of its application, advantages, disadvantages, and implementation in an effective planning, management, and evaluation (PME) system. A ZBB system requires administrators to: review all programs and expenditures annually, set clear cut goals, and analyze all possible alternatives for…

  11. Achievement-Based Resourcing.

    ERIC Educational Resources Information Center

    Fletcher, Mike; And Others

    1992-01-01

    This collection of seven articles examines achievement-based resourcing (ABR), the concept that the funding of educational institutions should be linked to their success in promoting student achievement, with a focus on the application of ABR to postsecondary education in the United Kingdom. The articles include: (1) "Introduction" (Mick…

  12. Risk Assessment: Evidence Base

    NASA Technical Reports Server (NTRS)

    Johnson-Throop, Kathy A.

    2007-01-01

    Human systems PRA (Probabilistic Risk Assessment: a) Provides quantitative measures of probability, consequence, and uncertainty; and b) Communicates risk and informs decision-making. Human health risks rated highest in ISS PRA are based on 1997 assessment of clinical events in analog operational settings. Much work remains to analyze remaining human health risks identified in Bioastronautics Roadmap.

  13. Concept-Based Learning

    ERIC Educational Resources Information Center

    Schill, Bethany; Howell, Linda

    2011-01-01

    A major part of developing concept-based instruction is the use of an overarching idea to provide a conceptual lens through which students view the content of a particular subject. By using a conceptual lens to focus learning, students think at a much deeper level about the content and its facts (Erickson 2007). Therefore, the authors collaborated…

  14. Skull Base Tumors

    NASA Astrophysics Data System (ADS)

    Schulz-Ertner, Daniela

    In skull base tumors associated with a low radiosensitivity for conventional radiotherapy (RT), irradiation with proton or carbon ion beams facilitates a safe and accurate application of high tumor doses due to the favorable beam localization properties of these particle beams. Cranial nerves, the brain stem and normal brain tissue can at the same time be optimally spared.

  15. Landscape-based Indicators

    EPA Science Inventory

    The report is based on data and experience gained through the GLNPO-funded Great Lakes Coastal Wetland Consortium (GLCWC) and the EPA-STAR funded Great Lakes Ecological Indicators Project (GLEI). EPA-MED author Trebitz and other MED personnel were collaborators on the GLEI proje...

  16. Nanocarbon-based photovoltaics.

    PubMed

    Bernardi, Marco; Lohrman, Jessica; Kumar, Priyank V; Kirkeminde, Alec; Ferralis, Nicola; Grossman, Jeffrey C; Ren, Shenqiang

    2012-10-23

    Carbon materials are excellent candidates for photovoltaic solar cells: they are Earth-abundant, possess high optical absorption, and maintain superior thermal and photostability. Here we report on solar cells with active layers made solely of carbon nanomaterials that present the same advantages of conjugated polymer-based solar cells, namely, solution processable, potentially flexible, and chemically tunable, but with increased photostability and the possibility to revert photodegradation. The device active layer composition is optimized using ab initio density functional theory calculations to predict type-II band alignment and Schottky barrier formation. The best device fabricated is composed of PC(70)BM fullerene, semiconducting single-walled carbon nanotubes, and reduced graphene oxide. This active-layer composition achieves a power conversion efficiency of 1.3%-a record for solar cells based on carbon as the active material-and we calculate efficiency limits of up to 13% for the devices fabricated in this work, comparable to those predicted for polymer solar cells employing PCBM as the acceptor. There is great promise for improving carbon-based solar cells considering the novelty of this type of device, the high photostability, and the availability of a large number of carbon materials with yet untapped potential for photovoltaics. Our results indicate a new strategy for efficient carbon-based, solution-processable, thin film, photostable solar cells.

  17. A Mars base

    NASA Technical Reports Server (NTRS)

    Soule, Veronique

    1989-01-01

    This study was initiated to provide an approach to the development of a permanently manned Mars base. The objectives for a permanently manned Mars base are numerous. Primarily, human presence on Mars will allow utilization of new resources for the improvement of the quality of life on Earth, allowing for new discoveries in technologies, the solar system, and human physiology. Such a mission would also encourage interaction between different countries, increasing international cooperation and leading to a stronger unification of mankind. Surface studies of Mars, scientific experiments in the multiple fields, the research for new minerals, and natural resource production are more immediate goals of the Mars mission. Finally, in the future, colonization of Mars will ensure man's perpetual presence in the universe. Specific objectives of this study were: (1) to design a Mars habitat that minimizes the mass delivered to the Mars surface, provides long-stay capability for the base crew, and accommodates future expansion and modification; (2) to develop a scenario of the construction of a permanently manned Mars base; and (3) to incorporate new and envisioned technologies.

  18. Service-based Solutions.

    ERIC Educational Resources Information Center

    Cummings, Lynda; Winston, Michael

    1998-01-01

    Describes the Solutions model used at Shelley High School in Idaho which gives students the opportunity to gain practical experience while tackling community problems. This approach is built on the three fundamentals of an integrated curriculum, a problem-solving focus, and service-based learning. Sample problems include increasing certain trout…

  19. Protein Crystal Based Nanomaterials

    NASA Technical Reports Server (NTRS)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  20. Biomechanical Analysis of the Fixation System for T-Shaped Acetabular Fracture

    PubMed Central

    Fan, Yanping; Lei, Jianyin; Zhu, Feng; Li, Zhiqiang; Chen, Weiyi; Liu, Ximing

    2015-01-01

    This study aims to evaluate the biomechanical mechanism of fixation systems in the most frequent T-shaped acetabular fracture using finite element method. The treatment of acetabular fractures was based on extensive clinical experience. Three commonly accepted rigid fixation methods (double column reconstruction plates (P × 2), anterior column plate combined with posterior column screws (P + PS), and anterior column plate combined with quadrilateral area screws (P + QS)) were chosen for evaluation. On the basis of the finite element model, the biomechanics of these fixation systems were assessed through effective stiffness levels, stress distributions, force transfers, and displacements along the fracture lines. All three fixation systems can be used to obtain effective functional outcomes. The third fixation system (P + QS) was the optimal method for T-shaped acetabular fracture. This fixation system may reduce many of the risks and limitations associated with other fixation systems. PMID:26495030

  1. Simplified AIP-II Peptidomimetics Are Potent Inhibitors of Staphylococcus aureus AgrC Quorum Sensing Receptors.

    PubMed

    Vasquez, Joseph K; Tal-Gan, Yftah; Cornilescu, Gabriel; Tyler, Kimberly A; Blackwell, Helen E

    2017-02-16

    The bacterial pathogen Staphylococcus aureus controls many aspects of virulence by using the accessory gene regulator (agr) quorum sensing (QS) system. The agr system is activated by a macrocyclic peptide signal known as an autoinducing peptide (AIP). We sought to develop structurally simplified mimetics of AIPs for use as chemical tools to study QS in S. aureus. Herein, we report new peptidomimetic AgrC receptor inhibitors based on a tail-truncated AIP-II peptide that have almost analogous inhibitory activities to the parent peptide. Structural comparison of one of these peptidomimetics to the parent peptide and a highly potent, all-peptide-derived, S. aureus agr inhibitor (AIP-III D4A) revealed a conserved hydrophobic motif and overall amphipathic nature. Our results suggest that the AIP scaffold is amenable to structural mimicry and minimization for the development of synthetic agr inhibitors.

  2. The onset of sediment transport in vegetated channels predicted by turbulent kinetic energy

    NASA Astrophysics Data System (ADS)

    Yang, J. Q.; Chung, H.; Nepf, H. M.

    2016-11-01

    This laboratory study advances our understanding of sediment transport in vegetated regions, by describing the impact of stem density on the critical velocity, Ucrit, at which sediment motion is initiated. Sparse emergent vegetation was modeled with rigid cylinders arranged in staggered arrays of different stem densities. The sediment transport rate, Qs, was measured over a range of current speeds using digital imaging, and the critical velocity was selected as the condition at which the magnitude of Qs crossed the noise threshold. For both grain sizes considered here (0.6-0.85 mm and 1.7-2 mm), Ucrit decreased with increasing stem density. This dependence can be explained by a threshold condition based on turbulent kinetic energy, kt, suggesting that near-bed turbulence intensity may be a more important control than bed shear stress on the initiation of sediment motion. The turbulent kinetic energy model unified the bare bed and vegetated channel measurements.

  3. Lidar base specification

    USGS Publications Warehouse

    Heidemann, Hans Karl.

    2012-01-01

    In late 2009, a $14.3 million allocation from the “American Recovery and Reinvestment Act” for new light detection and ranging (lidar) elevation data prompted the U.S. Geological Survey (USGS) National Geospatial Program (NGP) to develop a common base specification for all lidar data acquired for The National Map. Released as a draft in 2010 and formally published in 2012, the USGS–NGP “Lidar Base Specification Version 1.0” (now Lidar Base Specification) was quickly embraced as the foundation for numerous state, county, and foreign country lidar specifications. Prompted by a growing appreciation for the wide applicability and inherent value of lidar, a USGS-led consortium of Federal agencies commissioned a National Enhanced Elevation Assessment (NEEA) study in 2010 to quantify the costs and benefits of a national lidar program. A 2012 NEEA report documented a substantial return on such an investment, defined five Quality Levels (QL) for elevation data, and recommended an 8-year collection cycle of Quality Level 2 (QL2) lidar data as the optimum balance of benefit and affordability. In response to the study, the USGS–NGP established the 3D Elevation Program (3DEP) in 2013 as the interagency vehicle through which the NEEA recommendations could be realized. Lidar is a fast evolving technology, and much has changed in the industry since the final draft of the “Lidar Base Specification Version 1.0” was written. Lidar data have improved in accuracy and spatial resolution, geospatial accuracy standards have been revised by the American Society for Photogrammetry and Remote Sensing (ASPRS), industry standard file formats have been expanded, additional applications for lidar have become accepted, and the need for interoperable data across collections has been realized. This revision to the “Lidar Base Specification Version 1.0” publication addresses those changes and provides continued guidance towards a nationally consistent lidar dataset.

  4. Quorum-quenching limits quorum-sensing exploitation by signal-negative invaders

    PubMed Central

    Tannières, Mélanie; Lang, Julien; Barnier, Claudie; Shykoff, Jacqui A.; Faure, Denis

    2017-01-01

    Some bacteria produce and perceive quorum-sensing (QS) signals that coordinate several behaviours, including the costly processes that are exoenzyme production and plasmid transfer. In the case of plasmid transfer, the emergence of QS signal-altered invaders and their policing are poorly documented. In Agrobacterium tumefaciens, the virulence Ti-plasmid encodes both synthesis and sensing of QS-signals, which promote its transfer from a donor to a recipient cell. Here, we reported that QS-altered A. tumefaciens mutants arose during experimental evolution. All showed improved growth compared to their ancestor. Genome sequencing revealed that, though some had lost the Ti-plasmid, most were defective for QS-signal synthesis and Ti-plasmid conjugation (traR mutations) and one exhibited a QS-signal exploitation behaviour, using signal produced by other cells to enhance its own Ti-plasmid transfer. We explored mechanisms that can limit this QS-hijacking. We showed that the A. tumefaciens capacity to inactivate QS-signals by expressing QS-degrading enzyme could attenuate dissemination of the QS signal-negative Ti-plasmids. This work shows that enzymatic QS-disruption whether encoded by the QS-producing Ti-plasmid itself, by a companion plasmid in the same donor cells, or by one in the recipient cells, in all cases can serve as a mechanism for controlling QS exploitation by QS signal-negative mutants. PMID:28054641

  5. Quorum-quenching limits quorum-sensing exploitation by signal-negative invaders

    NASA Astrophysics Data System (ADS)

    Tannières, Mélanie; Lang, Julien; Barnier, Claudie; Shykoff, Jacqui A.; Faure, Denis

    2017-01-01

    Some bacteria produce and perceive quorum-sensing (QS) signals that coordinate several behaviours, including the costly processes that are exoenzyme production and plasmid transfer. In the case of plasmid transfer, the emergence of QS signal-altered invaders and their policing are poorly documented. In Agrobacterium tumefaciens, the virulence Ti-plasmid encodes both synthesis and sensing of QS-signals, which promote its transfer from a donor to a recipient cell. Here, we reported that QS-altered A. tumefaciens mutants arose during experimental evolution. All showed improved growth compared to their ancestor. Genome sequencing revealed that, though some had lost the Ti-plasmid, most were defective for QS-signal synthesis and Ti-plasmid conjugation (traR mutations) and one exhibited a QS-signal exploitation behaviour, using signal produced by other cells to enhance its own Ti-plasmid transfer. We explored mechanisms that can limit this QS-hijacking. We showed that the A. tumefaciens capacity to inactivate QS-signals by expressing QS-degrading enzyme could attenuate dissemination of the QS signal-negative Ti-plasmids. This work shows that enzymatic QS-disruption whether encoded by the QS-producing Ti-plasmid itself, by a companion plasmid in the same donor cells, or by one in the recipient cells, in all cases can serve as a mechanism for controlling QS exploitation by QS signal-negative mutants.

  6. A randomized, split-face clinical trial of Q-switched alexandrite laser versus Q-switched Nd:YAG laser in the treatment of bilateral nevus of Ota.

    PubMed

    Wen, Xiang; Li, Yong; Jiang, Xian

    2016-01-01

    Different types of Q-switched (QS) lasers have been used successfully to treat nevus of Ota. The purpose of this study was to compare the clinical efficacy and complication of QS alexandrite (QS Alex) laser versus QS neodymium:yttrium aluminum garnet (Nd:YAG) (QS Nd:YAG) laser for bilateral nevus of Ota. Seventeen patients with bilateral nevus of Ota were treated randomly with QS Alex in one half of face and QS Nd:YAG in the other half with an interval of at least 3 months between each. Subjective assessment was made by both patients and dermatologists. Patients were also examined for evidence of complications. All patients experienced improvement (p < 0.05). There was no statistically significant difference between the two sides (p > 0.05). The pain after a short period of laser therapy was more severe for QS Alex than for QS Nd:YAG laser. Vesicles developed in 1 patient after QS Alex therapy. Both QS Alex laser and QS Nd:YAG laser were equally effective at improving bilateral nevus of Ota. Patients tolerate QS Nd:YAG laser better than QS Alex laser.

  7. Phylogenetically Novel LuxI/LuxR-Type Quorum Sensing Systems Isolated Using a Metagenomic Approach

    PubMed Central

    Nasuno, Eri; Fujita, Masaki J.; Nakatsu, Cindy H.; Kamagata, Yoichi; Hanada, Satoshi

    2012-01-01

    A great deal of research has been done to understand bacterial cell-to-cell signaling systems, but there is still a large gap in our current knowledge because the majority of microorganisms in natural environments do not have cultivated representatives. Metagenomics is one approach to identify novel quorum sensing (QS) systems from uncultured bacteria in environmental samples. In this study, fosmid metagenomic libraries were constructed from a forest soil and an activated sludge from a coke plant, and the target genes were detected using a green fluorescent protein (GFP)-based Escherichia coli biosensor strain whose fluorescence was screened by spectrophotometry. DNA sequence analysis revealed two pairs of new LuxI family N-acyl-l-homoserine lactone (AHL) synthases and LuxR family transcriptional regulators (clones N16 and N52, designated AubI/AubR and AusI/AusR, respectively). AubI and AusI each produced an identical AHL, N-dodecanoyl-l-homoserine lactone (C12-HSL), as determined by nuclear magnetic resonance (NMR) and mass spectrometry. Phylogenetic analysis based on amino acid sequences suggested that AusI/AusR was from an uncultured member of the Betaproteobacteria and AubI/AubR was very deeply branched from previously described LuxI/LuxR homologues in isolates of the Proteobacteria. The phylogenetic position of AubI/AubR indicates that they represent a QS system not acquired recently from the Proteobacteria by horizontal gene transfer but share a more ancient ancestry. We demonstrated that metagenomic screening is useful to provide further insight into the phylogenetic diversity of bacterial QS systems by describing two new LuxI/LuxR-type QS systems from uncultured bacteria. PMID:22983963

  8. UCG process data base

    SciTech Connect

    Thorsness, C.B.; Cena, R.J.

    1980-05-01

    Process modeling in underground coal gasification (UCG) systems is a useful tool. Often, however, the experimental data necessary to test proposed models and mechanisms is not readily available. To help overcome this problem we describe in this paper a UCG Data Base we are developing to assist in making detailed data from DOE-sponsored field programs easily available. In addition, the data in the current data base are used to summarize the results of the Hoe Creek I, II, and III experiments. A statistical look at these data indicate a general lack of correlation between process variables. A simple gas compositional model is presented and is shown to be consistent with much of the available field data.

  9. Carbon Nanotube based Nanotechnolgy

    NASA Astrophysics Data System (ADS)

    Meyyappan, M.

    2000-10-01

    Carbon nanotube(CNT) was discovered in the early 1990s and is an off-spring of C60(the fullerene or buckyball). CNT, depending on chirality and diameter, can be metallic or semiconductor and thus allows formation of metal-semiconductor and semiconductor-semiconductor junctions. CNT exhibits extraordinary electrical and mechanical properties and offers remarkable potential for revolutionary applications in electronics devices, computing and data storage technology, sensors, composites, storage of hydrogen or lithium for battery development, nanoelectromechanical systems(NEMS), and as tip in scanning probe microscopy(SPM) for imaging and nanolithography. Thus the CNT synthesis, characterization and applications touch upon all disciplines of science and engineering. A common growth method now is based on CVD though surface catalysis is key to synthesis, in contrast to many CVD applications common in microelectronics. A plasma based variation is gaining some attention. This talk will provide an overview of CNT properties, growth methods, applications, and research challenges and opportunities ahead.

  10. Cosinor-based rhythmometry

    PubMed Central

    2014-01-01

    A brief overview is provided of cosinor-based techniques for the analysis of time series in chronobiology. Conceived as a regression problem, the method is applicable to non-equidistant data, a major advantage. Another dividend is the feasibility of deriving confidence intervals for parameters of rhythmic components of known periods, readily drawn from the least squares procedure, stressing the importance of prior (external) information. Originally developed for the analysis of short and sparse data series, the extended cosinor has been further developed for the analysis of long time series, focusing both on rhythm detection and parameter estimation. Attention is given to the assumptions underlying the use of the cosinor and ways to determine whether they are satisfied. In particular, ways of dealing with non-stationary data are presented. Examples illustrate the use of the different cosinor-based methods, extending their application from the study of circadian rhythms to the mapping of broad time structures (chronomes). PMID:24725531

  11. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseney, Jonathan A.; Arp, Larry Dean; Lindbergh, Charles

    1989-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar based subjected to one atmosphere internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design: (1) during construction; (2) under pressurization; and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the air-tightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the moon.

  12. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseny, Jonathan A.; Arp, Larry D.; Lindbergh, Charles

    1992-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar base subjected to 1-atm internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design (1) during construction, (2) under pressurization, and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the airtightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the Moon.

  13. Space construction data base

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Construction of large systems in space is a technology requiring the development of construction methods to deploy, assemble, and fabricate the elements comprising such systems. A construction method is comprised of all essential functions and operations and related support equipment necessary to accomplish a specific construction task in a particular way. The data base objective is to provide to the designers of large space systems a compendium of the various space construction methods which could have application to their projects.

  14. Flock-based microfluidics.

    PubMed

    Hitzbleck, Martina; Lovchik, Robert D; Delamarche, Emmanuel

    2013-05-21

    Flock-based microfluidics are created by depositing hydrophilic microfibers on an adhesive-coated substrate using an electric field. This enables the fabrication of self-powered microfluidics from one or more different kinds of fibers that form 2D and 3D flowpaths, which can wick 40 microliters of liquid per square centimeter. With this approach, large areas of functional wicking materials can be produced at extremely low cost.

  15. Sea Basing Logistiek

    DTIC Science & Technology

    2007-11-01

    iets wat nu voor zware goederen niet mogeljk is met de middelen binnen de Nederlandse krijgsmachit. Nederland heeft bijvoorbeeld (nog) geen specifieke...weer gevechtsklaar zijn. Nederlandse troepen voeren de reconstitute fase in het algemeen uit in Nederland . [Kang&Gue] A special concern in sea based...besluit Nederland zelf in te grijpen. De Nederlandse vredesmissie bevindt zich nabij de kust. maar ver van de grens met buurlanden. De operatie kan niet

  16. Vehicle Based Vector Sensor

    DTIC Science & Technology

    2015-09-28

    300001 1 of 16 VEHICLE-BASED VECTOR SENSOR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...unmanned underwater vehicle that can function as an acoustic vector sensor . (2) Description of the Prior Art [0004] It is known that a propagating...mechanics. An acoustic vector sensor measures the particle motion via an accelerometer and combines Attorney Docket No. 300001 2 of 16 the

  17. Pavement base drain evaluation

    NASA Astrophysics Data System (ADS)

    Hoffman, G. L.

    1981-06-01

    Portions of a highway drainage system design was revised. Essentially, the longitudinal drainage trench was moved closer to the pavement/shoulder joint, and the fine concrete sand layer was eliminated as a trench backfill material. The specified backfill material is a coarser crushed aggregate (pea gravel). An evaluation of the effects of these changes on pavement performance is given and the new pavement base drain system is compared to the older pipe foundation underdrain system at the same site.

  18. Granular loess classification based

    SciTech Connect

    Browzin, B.S.

    1985-05-01

    This paper discusses how loess might be identified by two index properties: the granulometric composition and the dry unit weight. These two indices are necessary but not always sufficient for identification of loess. On the basis of analyses of samples from three continents, it was concluded that the 0.01-0.5-mm fraction deserves the name loessial fraction. Based on the loessial fraction concept, a granulometric classification of loess is proposed. A triangular chart is used to classify loess.

  19. Refrigerator Based on Chemisorption

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.

    1987-01-01

    Reversible chemical reaction generates pressurized oxygen for cooling. Concept for cryogenic refrigerator based on chemical absorption of oxygen by praseodymium/cerium oxide (PCO) compound. Refrigerator produces cryogenic liquid for cooling infrared sensors. Also used for liquefying air and separating oxygen from nitrogen in air. In chemisorption refrigerator, PCO alternately absorbs and desorbs oxygen depending on whether cooled or heated. One pair of compressors accepts oxygen while others releases it. Compressed oxygen liquefied when precooked and expanded.

  20. Graphene-based biosensors

    NASA Astrophysics Data System (ADS)

    Lebedev, A. A.; Davydov, V. Yu.; Novikov, S. N.; Litvin, D. P.; Makarov, Yu. N.; Klimovich, V. B.; Samoilovich, M. P.

    2016-07-01

    Results of developing and testing graphene-based sensors capable of detecting protein molecules are presented. The biosensor operation was checked using an immunochemical system comprising fluorescein dye and monoclonal antifluorescein antibodies. The sensor detects fluorescein concentration on a level of 1-10 ng/mL and bovine serum albumin-fluorescein conjugate on a level of 1-5 ng/mL. The proposed device has good prospects for use for early diagnostics of various diseases.

  1. Projectile Base Flow Analysis

    DTIC Science & Technology

    2007-11-02

    S) AND ADDRESS(ES) DCW Industries, Inc. 5354 Palm Drive La Canada, CA 91011 8. PERFORMING ORGANIZATION...REPORT NUMBER DCW -38-R-05 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) U. S. Army Research Office...Turbulence Modeling for CFD, Second Edition, DCW Industries, Inc., La Cañada, CA. Wilcox, D. C. (2001), “Projectile Base Flow Analysis,” DCW

  2. [Evidence based medicine].

    PubMed

    Cuestas, Eduardo

    2005-01-01

    Evidence based medicine is a systematic method employed to secure the best scientific available evidence when making clinical decisions. Several steps are taken in these process, describing a clinical scenario, formulating a specific clinical question, searching the literature for the pertinent studies, selecting the relevant articles using rules of evidence, understanding and calculating measures of effect, and finally incorporating the evidence and patients preferences in the clinical decision process.

  3. AIS Data Base Generation.

    DTIC Science & Technology

    1981-04-01

    the area of natura , ianguage understanding by computer come from the fields of Computational Linguistics and Artificial Intelligence (Al). In the last...blocks of the data base. Another interestino approach to automated database generation is the :m,? taiean ty the Heurist~c P’ogrimming Projec~t at...operating system. 22 OSI’s Orientation O)perling Systems’ approach to automated database generatio,.I i_- irrneo ~~ ciilpport c,’ riformatlon

  4. Space Based Communications

    NASA Technical Reports Server (NTRS)

    Simpson, James; Denson, Erik; Valencia, Lisa; Birr, Richard

    2003-01-01

    Current space lift launches on the Eastern and Western Range require extensive ground-based real-time tracking, communications and command/control systems. These are expensive to maintain and operate and cover only limited geographical areas. Future spaceports will require new technologies to provide greater launch and landing opportunities, support simultaneous missions, and offer enhanced decision support models and simulation capabilities. These ranges must also have lower costs and reduced complexity while continuing to provide unsurpassed safety to the public, flight crew, personnel, vehicles and facilities. Commercial and government space-based assets for tracking and communications offer many attractive possibilities to help achieve these goals. This paper describes two NASA proof-of-concept projects that seek-to exploit the advantages of a space-based range: Iridium Flight Modem and Space-Based Telemetry and Range Safety (STARS). Iridium Flight Modem uses the commercial satellite system Iridium for extremely low cost, low rate two-way communications and has been successfully tested on four aircraft flights. A sister project at Goddard Space Flight Center's (GSFC) Wallops Flight Facility (WFF) using the Globalstar system has been tested on one rocket. The basic Iridium Flight Modem system consists of a L1 carrier Coarse/Acquisition (C/A)-Code Global Positioning System (GPS) receiver, an on-board computer, and a standard commercial satellite modem and antennas. STARS uses the much higher data rate NASA owned Tracking and Data Relay Satellite System (TDRSS), a C/A-Code GPS receiver, an experimental low-power transceiver, custom built command and data handler processor, and digitized flight termination system (FTS) commands. STARS is scheduled to fly on an F-15 at Dryden Flight Research Center in the spring of 2003, with follow-on tests over the next several years.

  5. Insights of biosurfactant producing Serratia marcescens strain W2.3 isolated from diseased tilapia fish: a draft genome analysis

    PubMed Central

    2013-01-01

    Background Serratia marcescens is an opportunistic bacterial pathogen with broad range of host ranging from vertebrates, invertebrates and plants. S. marcescens strain W2.3 was isolated from a diseased tilapia fish and it was suspected to be the causal agent for the fish disease as virulence genes were found within its genome. In this study, for the first time, the genome sequences of S. marcescens strain W2.3 were sequenced using the Illumina MiSeq platform. Result Several virulent factors of S. marcescens such as serrawettin, a biosurfactant, has been reported to be regulated by N-acyl homoserine lactone (AHL)-based quorum sensing (QS). In our previous studies, an unusual AHL with long acyl side chain was detected from this isolate suggesting the possibility of novel virulence factors regulation. This evokes our interest in the genome of this bacterial strain and hereby we present the draft genome of S. marcescens W2.3, which carries the serrawettin production gene, swrA and the AHL-based QS transcriptional regulator gene, luxR which is an orphan luxR. Conclusion With the availability of the whole genome sequences of S. marcescens W2.3, this will pave the way for the study of the QS-mediated genes expression in this bacterium. PMID:24148830

  6. Quorum sensing in marine snow and its possible influence on production of extracellular hydrolytic enzymes in marine snow bacterium Pantoea ananatis B9.

    PubMed

    Jatt, Abdul Nabi; Tang, Kaihao; Liu, Jiwen; Zhang, Zenghu; Zhang, Xiao-Hua

    2015-02-01

    Marine snow is a continuous shower of organic and inorganic detritus, and plays a crucial role in transporting materials from the sea surface to the deep ocean. The aims of the current study were to identify N-acyl homoserine lactone (AHL)-based quorum sensing (QS) signaling molecules directly from marine snow particles and to investigate the possible regulatory link between QS signals and extracellular hydrolytic enzymes produced by marine snow bacteria. The marine snow samples were collected from the surface water of China marginal seas. Two AHLs, i.e. 3OC6-HSL and C8-HSL, were identified directly from marine snow particles, while six different AHL signals, i.e. C4-HSL, 3OC6-HSL, C6-HSL, C10-HSL, C12-HSL and C14-HSL were produced by Pantoea ananatis B9 inhabiting natural marine snow particles. Of the extracellular hydrolytic enzymes produced by P. ananatis B9, alkaline phosphatase activity was highly enhanced in growth medium supplemented with exogenous AHL (C10-HSL), while quorum quenching enzyme (AiiA) drastically reduced the enzyme activity. To our knowledge, this is the first report revealing six different AHL signals produced by P. ananatis B9 and AHL-based QS system enhanced the extracellular hydrolytic enzyme in P. ananatis B9. Furthermore, this study first time revealing 3OC6-HSL production by Paracoccus carotinifaciens affiliated with Alphaproteobacteria.

  7. Example based lesion segmentation

    NASA Astrophysics Data System (ADS)

    Roy, Snehashis; He, Qing; Carass, Aaron; Jog, Amod; Cuzzocreo, Jennifer L.; Reich, Daniel S.; Prince, Jerry; Pham, Dzung

    2014-03-01

    Automatic and accurate detection of white matter lesions is a significant step toward understanding the progression of many diseases, like Alzheimer's disease or multiple sclerosis. Multi-modal MR images are often used to segment T2 white matter lesions that can represent regions of demyelination or ischemia. Some automated lesion segmentation methods describe the lesion intensities using generative models, and then classify the lesions with some combination of heuristics and cost minimization. In contrast, we propose a patch-based method, in which lesions are found using examples from an atlas containing multi-modal MR images and corresponding manual delineations of lesions. Patches from subject MR images are matched to patches from the atlas and lesion memberships are found based on patch similarity weights. We experiment on 43 subjects with MS, whose scans show various levels of lesion-load. We demonstrate significant improvement in Dice coefficient and total lesion volume compared to a state of the art model-based lesion segmentation method, indicating more accurate delineation of lesions.

  8. AFE base flow computations

    NASA Technical Reports Server (NTRS)

    Venkatapathy, Ethiraj; Prabhu, Dinesh K.; Palmer, Grant

    1991-01-01

    Hypersonic wake flows behind the Aeroassist Flight Experiment (AFE) geometry are analyzed using two Navier-Stokes flow solvers. Many of the AFE wake features observed in ballistic-range shadowgraphs are simulated using a simple, two-dimensional semicylinder geometry at moderate angles of attack. At free-stream conditions corresponding to a Hypersonic Free Flight Facility (HFFF) AFE experiment, the three-dimensional base flow for the AFE geometry is computed using an ideal-gas, Navier-Stokes solver. The computed results agree reasonably well with the shadowgraphs taken at the HFFF. An ideal-gas and a nonequilibrium Navier-Stokes solver have been coupled and applied to the complete flow around the AFE vehicle at the free-stream conditions corresponding to a nomial trajectory point. Limitations of the coupled ideal-gas and nonequilibrium solution are discussed. The nonequilibrium base flow solution is analyzed for the wake radiation and the radiation profiles along various lines of sight are compared. Finally, the wake unsteadiness is predicted using experimental correlations and the numerical solutions. An adaptive grid code, SAGE, has been used in all the simulations to enhance the solution accuracy. The grid adaptation is found to be necessary in obtaining base flow solutions with accurate flow features.

  9. RNA based evolutionary optimization

    NASA Astrophysics Data System (ADS)

    Schuster, Peter

    1993-12-01

    The notion of an RNA world has been introduced for a prebiotic scenario that is dominated by RNA molecules and their properties, in particular their capabilities to act as templates for reproduction and as catalysts for several cleavage and ligation reactions of polynucleotides and polypeptides. This notion is used here also for simple experimental assays which are well suited to study evolution in the test tube. In molecular evolution experiments fitness is determined in essence by the molecular structures of RNA molecules. Evidence is presented for adaptation to environment in cell-free media. RNA based molecular evolution experiments have led to interesting spin-offs in biotechnology, commonly called ‘applied molecular evolution’, which make use of Darwinian trial-and-error strategies in order to synthesize new pharmacological compounds and other advanced materials on a biological basis. Error-propagation in RNA replication leads to formation of mutant spectra called ‘quasispecies’. An increase in the error rate broadens the mutant spectrum. There exists a sharply defined threshold beyond which heredity breaks down and evolutionary adaptation becomes impossible. Almost all RNA viruses studied so far operate at conditions close to this error threshold. Quasispecies and error thresholds are important for an understanding of RNA virus evolution, and they may help to develop novel antiviral strategies. Evolution of RNA molecules can be studied and interpreted by considering secondary structures. The notion of sequence space introduces a distance between pairs of RNA sequences which is tantamount to counting the minimal number of point mutations required to convert the sequences into each other. The mean sensitivity of RNA secondary structures to mutation depends strongly on the base pairing alphabet: structures from sequences which contain only one base pair (GC or AU are much less stable against mutation than those derived from the natural (AUGC) sequences

  10. [Stewart's acid-base approach].

    PubMed

    Funk, Georg-Christian

    2007-01-01

    In addition to paCO(2), Stewart's acid base model takes into account the influence of albumin, inorganic phosphate, electrolytes and lactate on acid-base equilibrium. It allows a comprehensive and quantitative analysis of acid-base disorders. Particularly simultaneous and mixed metabolic acid-base disorders, which are common in critically ill patients, can be assessed. Stewart's approach is therefore a valuable tool in addition to the customary acid-base approach based on bicarbonate or base excess. However, some chemical aspects of Stewart's approach remain controversial.

  11. Polyolefin-Based Aerogels

    NASA Technical Reports Server (NTRS)

    Lee, Je Kyun; Gould, George

    2012-01-01

    An organic polybutadiene (PB) rubberbased aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection, exhibiting the flexibility, resiliency, toughness, and durability typical of the parent polymer, yet with the low density and superior insulation properties associated with the aerogels. The rubbery behaviors of the PB rubber-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogel insulation materials. Additionally, with higher content of hydrogen in their structure, the PB rubber aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. Since PB rubber aerogels also exhibit good hydrophobicity due to their hydrocarbon molecular structure, they will provide better performance reliability and durability as well as simpler, more economic, and environmentally friendly production over the conventional silica or other inorganic-based aerogels, which require chemical treatment to make them hydrophobic. Inorganic aerogels such as silica aerogels demonstrate many unusual and useful properties. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven one promising approach, providing a conveniently fielded form factor that is relatively robust toward handling in industrial environments compared to silica aerogel monoliths. However, the flexible silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain applications. Although the cross-linked organic aerogels such as resorcinol-formaldehyde (RF), polyisocyanurate, and cellulose aerogels show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient

  12. Internet Based Remote Operations

    NASA Technical Reports Server (NTRS)

    Chamberlain, James

    1999-01-01

    This is the Final Report for the Internet Based Remote Operations Contract, has performed payload operations research support tasks March 1999 through September 1999. These tasks support the GSD goal of developing a secure, inexpensive data, voice, and video mission communications capability between remote payload investigators and the NASA payload operations team in the International Space Station (ISS) era. AZTek has provided feedback from the NASA payload community by utilizing its extensive payload development and operations experience to test and evaluate remote payload operations systems. AZTek has focused on use of the "public Internet" and inexpensive, Commercial-off-the-shelf (COTS) Internet-based tools that would most benefit "small" (e.g., $2 Million or less) payloads and small developers without permanent remote operations facilities. Such projects have limited budgets to support installation and development of high-speed dedicated communications links and high-end, custom ground support equipment and software. The primary conclusions of the study are as follows: (1) The trend of using Internet technology for "live" collaborative applications such as telescience will continue. The GSD-developed data and voice capabilities continued to work well over the "public" Internet during this period. 2. Transmitting multiple voice streams from a voice-conferencing server to a client PC to be mixed and played on the PC is feasible. 3. There are two classes of voice vendors in the market: - Large traditional phone equipment vendors pursuing integration of PSTN with Internet, and Small Internet startups.The key to selecting a vendor will be to find a company sufficiently large and established to provide a base voice-conferencing software product line for the next several years.

  13. Characteristics Data Base

    SciTech Connect

    Lewis, E.D.; Moore, R.S. )

    1990-08-01

    The LWR Serial Numbers Database System (SNDB) contains detailed data about individual, historically discharged LWR spent fuel assemblies. This data includes the reactor where used, the year the assemblies were discharged, the pool where they are currently stored, assembly type, burnup, weight, enrichment, and an estimate of their radiological properties. This information is distributed on floppy disks to users in the nuclear industry to assist in planning for the permanent nuclear waste repository. This document describes the design and development of the SNDB. It provides a complete description of the file structures and an outline of the major code modules. It serves as a reference for a programmer maintaining the system, or for others interested in the technical detail of this database. This is the initial version of the SNDB. It contains historical data through December 31, 1987, obtained from the Energy Information Administration (EIA). EIA obtains the data from the utility companies via the RW-859 Survey Form. It evaluates and standardizes the data and distributes the resulting batch level database as a large file on magnetic tape. The Characteristics Data Base obtains this database for use in the LWR Quantities Data Base. Additionally, the CDB obtains the individual assembly level detail from EIA for use in the SNDB. While the Quantities Data Base retains only the level of detail necessary for its reporting, the SNDB does retain and use the batch level data to assist in the identification of a particular assembly serial number. We expect to update the SNDB on an annual basis, as new historical data becomes available.

  14. Sustainability Base Construction Update

    NASA Technical Reports Server (NTRS)

    Mewhinney, Michael

    2012-01-01

    Construction of the new Sustainability Base Collaborative support facility, expected to become the highest performing building in the federal government continues at NASA's Ames Research Center, Moffet Field, Calif. The new building is designed to achieve a platinum rating under the leadership in Energy and Environment Design (LEED) new construction standards for environmentally sustainable construction developed by the U. S. Green Building Council, Washington, D. C. When completed by the end of 2011, the $20.6 million building will feature near zero net energy consumption, use 90 percent less potable water than conventionally build buildings of equivalent size, and will result in reduced building maintenance costs.

  15. [Evidence-based physiotherapy].

    PubMed

    Bender, Tamás

    2013-12-01

    This article on physiotherapy presents some current evidence stating the strengths and weaknesses of the physiotherapeutic procedures. In the area of physiotherapy empirical data obtained during decades were overtaken by evidence from current studies. The author points out the great problem of physiotherapy, namely the heterogeneity of the applied parameters. Knowledge of current evidence may be very important and helpful for the physicians, but the author proposes, from the practical point of view, that physiotherapeutical procedures based on exprience and used for many years should not be entirely neglected. Nowadays physiotherapy plays an important role in the treament of locomotor diseases but its use is increasing in other fields of medicine, as well.

  16. Covering all the bases

    SciTech Connect

    Reimers, R.F.; Gross, M.P.

    1996-04-01

    The use of silent discharge plasma technology (SDPT) to treat volatile organic compounds (VOCs) at McClellan Air Force Base during a two-month test is described. SDPT was developed by Los Alamos National Laboratory and licensed to High Mesa Technologies. SDPT was used at McClellan to treat off-gases from air strippers, vapor-extraction systems, and incinerators at flow rates up to 10.4 scfm; destruction and removal efficiencies up to 99.4% were achieved. SDPT can also treat organic liquids by adding a packaged-bed reactor to the first stage system.

  17. NICKEL-BASE ALLOY

    DOEpatents

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  18. Base drive circuit

    DOEpatents

    Lange, Arnold C.

    1995-01-01

    An improved base drive circuit (10) having a level shifter (24) for providing bistable input signals to a pair of non-linear delays (30, 32). The non-linear delays (30, 32) provide gate control to a corresponding pair of field effect transistors (100, 106) through a corresponding pair of buffer components (88, 94). The non-linear delays (30, 32) provide delayed turn-on for each of the field effect transistors (100, 106) while an associated pair of transistors (72, 80) shunt the non-linear delays (30, 32) during turn-off of the associated field effect transistor (100, 106).

  19. Internet-Based Communication

    PubMed Central

    Gernsbacher, Morton Ann

    2015-01-01

    Google the question, “How is the Internet changing the way we communicate?,” and you will find no shortage of opinions, or fears, about the Internet altering the way we communicate. Although the Internet is not necessarily making communication briefer (neither is the Internet making communication less formal), the Internet is manifesting our preference for writing over speaking. I propose that our preference for communicating through Internet-based text derives from a fundamental feature of writing: In contrast to speech, which is most often synchronous, text is most often asynchronous. PMID:26330702

  20. Mars base buildup scenarios

    SciTech Connect

    Blacic, J.D.

    1985-01-01

    Two surface base build-up scenarios are presented in order to help visualize the mission and to serve as a basis for trade studies. In the first scenario, direct manned landings on the Martian surface occur early in the missions and scientific investigation is the main driver and rationale. In the second scenario, early development of an infrastructure to exploite the volatile resources of the Martian moons for economic purposes is emphasized. Scientific exploration of the surface is delayed at first, but once begun develops rapidly aided by the presence of a permanently manned orbital station.

  1. Alphavirus-Based Vaccines.

    PubMed

    Lundstrom, Kenneth

    2016-01-01

    Alphavirus vectors based on Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus have been widely applied for vaccine development. Naked RNA replicons, recombinant viral particles, and layered DNA vectors have been subjected to immunization in preclinical animal models with antigens for viral targets and tumor antigens. Moreover, a limited number of clinical trials have been conducted in humans. Vaccination with alphavirus vectors has demonstrated efficient immune responses and has showed protection against challenges with lethal doses of virus and tumor cells, respectively. Moreover, vaccines have been developed against alphaviruses causing epidemics such as Chikungunya virus.

  2. Office-based anesthesia.

    PubMed

    Treasure, Trevor; Bennett, Jeffrey

    2007-02-01

    The practice of office-based oral and maxillofacial surgery is continuously expanding and involves the management of a diverse population in regards to the surgical procedures performed within the office and the age and medical health of the patients treated within the office. Comfort, cooperation, and hemodynamic stability are critical to satisfactorily accomplishing the surgical procedure. Various anesthetic techniques are used, including local anesthesia, anxiolysis, analgesia and sedation, and general anesthesia. The topic is vast and too extensive to be fully discussed in this article. The intent of this article is to provide a discussion of some fundamental concepts that can optimize anesthetic safety and care.

  3. Synchrotron based proton drivers

    SciTech Connect

    Weiren Chou

    2002-09-19

    Proton drivers are the proton sources that produce intense short proton bunches. They have a wide range of applications. This paper discusses the proton drivers based on high-intensity proton synchrotrons. It gives a review of the high-intensity proton sources over the world and a brief report on recent developments in this field in the U.S. high-energy physics (HEP) community. The Fermilab Proton Driver is used as a case study for a number of challenging technical design issues.

  4. TUNGSTEN BASE ALLOYS

    DOEpatents

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  5. Accelerator-based BNCT.

    PubMed

    Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

    2014-06-01

    The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases.

  6. Base drive circuit

    DOEpatents

    Lange, A.C.

    1995-04-04

    An improved base drive circuit having a level shifter for providing bistable input signals to a pair of non-linear delays. The non-linear delays provide gate control to a corresponding pair of field effect transistors through a corresponding pair of buffer components. The non-linear delays provide delayed turn-on for each of the field effect transistors while an associated pair of transistors shunt the non-linear delays during turn-off of the associated field effect transistor. 2 figures.

  7. Moon base reactor system

    NASA Technical Reports Server (NTRS)

    Chavez, H.; Flores, J.; Nguyen, M.; Carsen, K.

    1989-01-01

    The objective of our reactor design is to supply a lunar-based research facility with 20 MW(e). The fundamental layout of this lunar-based system includes the reactor, power conversion devices, and a radiator. The additional aim of this reactor is a longevity of 12 to 15 years. The reactor is a liquid metal fast breeder that has a breeding ratio very close to 1.0. The geometry of the core is cylindrical. The metallic fuel rods are of beryllium oxide enriched with varying degrees of uranium, with a beryllium core reflector. The liquid metal coolant chosen was natural lithium. After the liquid metal coolant leaves the reactor, it goes directly into the power conversion devices. The power conversion devices are Stirling engines. The heated coolant acts as a hot reservoir to the device. It then enters the radiator to be cooled and reenters the Stirling engine acting as a cold reservoir. The engines' operating fluid is helium, a highly conductive gas. These Stirling engines are hermetically sealed. Although natural lithium produces a lower breeding ratio, it does have a larger temperature range than sodium. It is also corrosive to steel. This is why the container material must be carefully chosen. One option is to use an expensive alloy of cerbium and zirconium. The radiator must be made of a highly conductive material whose melting point temperature is not exceeded in the reactor and whose structural strength can withstand meteor showers.

  8. DVD Based Electronic Pulser

    SciTech Connect

    Morris, Scott J.; Pratt, Rick M.; Hughes, Michael A.; Kouzes, Richard T.; Pitts, W. K.; Robinson, Eric E.

    2005-10-01

    This paper describes the design, construction, and testing of a DVD based electronic pulser system (DVDEPS). Such a device is used to generate pulse streams for simulation of both gamma and neutron detector systems. The DVDEPS reproduces a random pulse stream of a full HPGe spectrum as well as a digital pulse stream representing the output of a neutron multiplicity detector. The exchangeable DVD media contains over an hour of data for both detector systems and can contain an arbitrary gamma spectrum and neutron pulse stream. The data is written to the DVD using a desktop computer program from either actual or simulated spectra. The targeted use of the DVDEPS is authentication or validation of monitoring equipment for non-proliferation purposes, but it is also of general use whenever a complex data stream is required. The DVD based pulser combines the storage capacity and simplicity of DVD technology with commonly available electronic components to build a relatively inexpensive yet highly capable testing instrument.

  9. DVD Based Electronic Pulser

    SciTech Connect

    Morris, Scott J.; Pratt, Rick M.; Hughes, Michael A.; Kouzes, Richard T.; Pitts, W. K.; Robinson, Eric

    2006-08-01

    This article describes the design, construction, and testing of a digital versatile disc (DVD) based electronic pulser system (DVDEPS). Such a device is used to generate pulse streams for simulation of both gamma and neutron detector systems. The DVDEPS reproduces a random pulse stream of a full high purity germanium (HPGe) spectrum as well as a digital pulse stream representing the output of a neutron multiplicity detector. The exchangeable DVD media contains over an hour of data for both detector systems and can contain an arbitrary gamma spectrum and neutron pulse stream. The data is written to the DVD using a desktop computer program from either real or simulated spectra. The targeted use of the DVDEPS is authentication or validation of monitoring equipment for non-proliferation purposes, but it is also of general use in a variety of sitiuations. The DVD based pulser combines the storage capacity and simplicity of DVD technology with commonly available electronic components to build a relatively inexpensive yet highly capable testing instrument.

  10. Ground based infrared astronomy

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.

    1988-01-01

    Infrared spectroscopic instrumentation has been developed for ground-based measurements of astrophysical objects in the intermediate infrared. A conventional Michelson interferometer is limited for astronomical applications in the intermediate infrared by quantum noise fluctuations in the radiation form the source and/or background incident on the detector, and the multiplex advantage is no longer available. One feasible approach to recovering the multiplex advantage is post-dispersion. The infrared signal after passing through telescope and interferometer, is dispersed by a low resolution grating spectrometer onto an array of detectors. The feasibility of the post-dispersion system has been demonstrated with observations of astrophysical objects in the 5 and 10 micrometer atmospheric windows from ground-based telescopes. During FY87/88 the post-disperser was used at the Kitt Peak 4-meter telescope and McMath telescope with facility Fourier transform spectrometers. Jupiter, Saturn, Mars, and Venus were observed. On Jupiter, the resolution at 12 micrometer was 0.01/cm, considerably higher than had been acheived previously. The spectrum contains Jovian ethane and acetylene emission. Construction was begun on the large cryogenic grating spectrometer.

  11. Model Based Definition

    NASA Technical Reports Server (NTRS)

    Rowe, Sidney E.

    2010-01-01

    In September 2007, the Engineering Directorate at the Marshall Space Flight Center (MSFC) created the Design System Focus Team (DSFT). MSFC was responsible for the in-house design and development of the Ares 1 Upper Stage and the Engineering Directorate was preparing to deploy a new electronic Configuration Management and Data Management System with the Design Data Management System (DDMS) based upon a Commercial Off The Shelf (COTS) Product Data Management (PDM) System. The DSFT was to establish standardized CAD practices and a new data life cycle for design data. Of special interest here, the design teams were to implement Model Based Definition (MBD) in support of the Upper Stage manufacturing contract. It is noted that this MBD does use partially dimensioned drawings for auxiliary information to the model. The design data lifecycle implemented several new release states to be used prior to formal release that allowed the models to move through a flow of progressive maturity. The DSFT identified some 17 Lessons Learned as outcomes of the standards development, pathfinder deployments and initial application to the Upper Stage design completion. Some of the high value examples are reviewed.

  12. Skyline based terrain matching

    NASA Technical Reports Server (NTRS)

    Page, Lance A.

    1990-01-01

    Skyline-based terrain matching, a new method for locating the vantage point of stereo camera or laser range-finding measurements on a global map previously prepared by satellite or aerial mapping is described. The orientation of the vantage is assumed known, but its translational parameters are determined by the algorithm. Skylines, or occluding contours, can be extracted from the sensory measurements taken by an autonomous vehicle. They can also be modeled from the global map, given a vantage estimate from which to start. The two sets of skylines, represented in cylindrical coordinates about either the true or the estimated vantage, are employed as 'features' or reference objects common to both sources of information. The terrain matching problem is formulated in terms of finding a translation between the respective representations of the skylines, by approximating the two sets of skylines as identical features (curves) on the actual terrain. The search for this translation is based on selecting the longest of the minimum-distance vectors between corresponding curves from the two sets of skylines. In successive iterations of the algorithm, the approximation that the two sets of curves are identical becomes more accurate, and the vantage estimate continues to improve. The algorithm was implemented and evaluated on a simulated terrain. Illustrations and examples are included.

  13. Model-Based Systems

    NASA Technical Reports Server (NTRS)

    Frisch, Harold P.

    2007-01-01

    Engineers, who design systems using text specification documents, focus their work upon the completed system to meet Performance, time and budget goals. Consistency and integrity is difficult to maintain within text documents for a single complex system and more difficult to maintain as several systems are combined into higher-level systems, are maintained over decades, and evolve technically and in performance through updates. This system design approach frequently results in major changes during the system integration and test phase, and in time and budget overruns. Engineers who build system specification documents within a model-based systems environment go a step further and aggregate all of the data. They interrelate all of the data to insure consistency and integrity. After the model is constructed, the various system specification documents are prepared, all from the same database. The consistency and integrity of the model is assured, therefore the consistency and integrity of the various specification documents is insured. This article attempts to define model-based systems relative to such an environment. The intent is to expose the complexity of the enabling problem by outlining what is needed, why it is needed and how needs are being addressed by international standards writing teams.

  14. Nanotechnology-Based Cosmeceuticals

    PubMed Central

    Lohani, Alka; Verma, Anurag; Joshi, Himanshi; Yadav, Niti; Karki, Neha

    2014-01-01

    Cosmeceuticals are the fastest growing segment of the personal care industry, and a number of topical cosmeceutical treatments for conditions such as photoaging, hyperpigmentation, wrinkles, and hair damage have come into widespread use. In the cosmeceutical arena nanotechnology has played an important role. Using new techniques to manipulate matter at an atomic or molecular level, they have been at the root of numerous innovations, opening up new perspectives for the future of cosmeceutical industry. Nanotechnology-based cosmeceuticals offer the advantage of diversity in products, and increased bioavailability of active ingredients and increase the aesthetic appeal of cosmeceutical products with prolonged effects. However increased use of nanotechnology in cosmeceuticals has raised concern about the possible penetration of nanoparticles through the skin and potential hazards to the human health. This review outlines the different nanoparticles used in various classes of cosmeceuticals, nanotechnology-based cosmeceutical products present in the market, and the potential risk caused by nanoparticles on exposure and recent regulatory steps taken to overcome them. PMID:24963412

  15. Droplet based microfluidics.

    PubMed

    Seemann, Ralf; Brinkmann, Martin; Pfohl, Thomas; Herminghaus, Stephan

    2012-01-01

    Droplet based microfluidics is a rapidly growing interdisciplinary field of research combining soft matter physics, biochemistry and microsystems engineering. Its applications range from fast analytical systems or the synthesis of advanced materials to protein crystallization and biological assays for living cells. Precise control of droplet volumes and reliable manipulation of individual droplets such as coalescence, mixing of their contents, and sorting in combination with fast analysis tools allow us to perform chemical reactions inside the droplets under defined conditions. In this paper, we will review available drop generation and manipulation techniques. The main focus of this review is not to be comprehensive and explain all techniques in great detail but to identify and shed light on similarities and underlying physical principles. Since geometry and wetting properties of the microfluidic channels are crucial factors for droplet generation, we also briefly describe typical device fabrication methods in droplet based microfluidics. Examples of applications and reaction schemes which rely on the discussed manipulation techniques are also presented, such as the fabrication of special materials and biophysical experiments.

  16. SPACE BASED INTERCEPTOR SCALING

    SciTech Connect

    G. CANAVAN

    2001-02-01

    Space Based Interceptor (SBI) have ranges that are adequate to address rogue ICBMs. They are not overly sensitive to 30-60 s delay times. Current technologies would support boost phase intercept with about 150 interceptors. Higher acceleration and velocity could reduce than number by about a factor of 3 at the cost of heavier and more expensive Kinetic Kill Vehicles (KKVs). 6g SBI would reduce optimal constellation costs by about 35%; 8g SBI would reduce them another 20%. Interceptor ranges fall rapidly with theater missile range. Constellations increase significantly for ranges under 3,000 km, even with advanced interceptor technology. For distributed launches, these estimates recover earlier strategic scalings, which demonstrate the improved absentee ratio for larger or multiple launch areas. Constellations increase with the number of missiles and the number of interceptors launched at each. The economic estimates above suggest that two SBI per missile with a modest midcourse underlay is appropriate. The SBI KKV technology would appear to be common for space- and surface-based boost phase systems, and could have synergisms with improved midcourse intercept and discrimination systems. While advanced technology could be helpful in reducing costs, particularly for short range theater missiles, current technology appears adequate for pressing rogue ICBM, accidental, and unauthorized launches.

  17. Process-Oriented Review of Bacterial Quorum Quenching for Membrane Biofouling Mitigation in Membrane Bioreactors (MBRs)

    PubMed Central

    Bouayed, Naila; Dietrich, Nicolas; Lafforgue, Christine; Lee, Chung-Hak; Guigui, Christelle

    2016-01-01

    Quorum Quenching (QQ) has been developed over the last few years to overcome practical issues related to membrane biofouling, which is currently the major difficulty thwarting the extensive development of membrane bioreactors (MBRs). QQ is the disruption of Quorum Sensing (QS), cell-to-cell communication enabling the bacteria to harmonize their behavior. The production of biofilm, which is recognized as a major part of the biocake formed on a membrane surface, and which leads to biofouling, has been found to be one of the bacterial behaviors controlled by QS. Since the enzymatic disruption of QS was reported to be efficient as a membrane biofouling mitigation technique in MBRs, the application of QQ to lab-scale MBRs has been the subject of much research using different approaches under different operating conditions. This paper gives an overview of the effectiveness of QQ in mitigating membrane biofouling in MBRs. It is based on the results of previous studies, using two microbial strains, Rhodococcus sp. BH4 and Pseudomonas sp. 1A1. The effect of bacterial QQ on the physical phenomena of the MBR process is analyzed, adopting an original multi-scale approach. Finally, the potential influence of the MBR operating conditions on QQ effectiveness is discussed. PMID:27983578

  18. Clinical and environmental genotypes of Vibrio vulnificus display distinct, quorum-sensing-mediated, chitin detachment dynamics

    PubMed Central

    Phippen, Britney L.; Oliver, James D.

    2015-01-01

    The ability for bacteria to attach to and detach from various substrata is important for colonization, survival and transitioning to new environments. An opportunistic human pathogen, Vibrio vulnificus, can cause potentially fatal septicemia after ingestion of undercooked seafood. Based on genetic polymorphisms, strains of this species are subtyped into clinical (C) and environmental (E) genotypes. Vibrio vulnificus readily associates with chitin, thus we investigated chitin detachment dynamics in these disparate genotypes. We found that C-genotypes detach significantly more than E-genotypes after 24 hours in aerobic as well as anaerobic conditions. Furthermore, expression of genes involved in type IV pilin production was significantly downregulated in C-genotypes compared to E-genotypes, suggesting an importance in detachment. Interestingly, gbpA, a gene that has been shown to be important in host colonization in V. cholerae, was upregulated in the C-genotypes during detachment. Additionally, we found that C-genotypes detached to a greater extent, and produced more quorum-sensing (QS) autoinducer-2 molecules relative to E-genotypes, which suggests a role for QS in detachment. These findings suggest that for V. vulnificus, QS-mediated detachment may be a potential mechanism for transitioning into a human host for C-genotypes, while facilitating E-genotype maintenance in the estuarine environment. PMID:26377182

  19. Production of acylated homoserine lactone by gram-positive bacteria isolated from marine water.

    PubMed

    Biswa, Pramal; Doble, Mukesh

    2013-06-01

    Acylated homoserine lactone (AHL)-based quorum sensing (QS) has been reported to be present only in Gram-negative microorganisms. Isolation of a novel Gram-positive microorganism from sea water, capable of producing AHL, is reported here. The isolate (GenBank: JF915892, designated as MPO) belonging to the Exiguobacterium genera is capable of inducing the AHL bioreporters, namely Chromobacterium violaceum CV026, Agrobacterium tumefaceins A136, and E. coli JM 109(psb1075). This inducer is characterized as C3-oxo-octanoyl homoserine lactone (OOHL), and its production reaches a maximum of 15.6 μg L(-1), during the stationary growth phase of the organism. MPO extract when exogenously added inhibits the formation of biofilm for the same organism and lowers the extracellular polymeric substances, indicating an AHL-associated phenotypic trait. The isolated sequence of a probable LuxR homolog from MPO (designated as ExgR) shows similar functional domains and contains conserved residues in LuxR from other known bacterial QS LuxR regulators. Also present immediately downstream to ExgR was found a sequence showing homology to known LuxI synthase of Pseudomonas putida. qPCR analysis suggests an increment in exgR mRNA on addition of AHL, further proving the role of ExgR as a QS regulator.

  20. In silico and experimental methods revealed highly diverse bacteria with quorum sensing and aromatics biodegradation systems--a potential broad application on bioremediation.

    PubMed

    Huang, Yili; Zeng, Yanhua; Yu, Zhiliang; Zhang, Jing; Feng, Hao; Lin, Xiuchun

    2013-11-01

    Phylogenetic overlaps between aromatics-degrading bacteria and acyl-homoserine-lactone (AHL) or autoinducer (AI) based quorum-sensing (QS) bacteria were evident in literatures; however, the diversity of bacteria with both activities had never been finely described. In-silico searching in NCBI genome database revealed that more than 11% of investigated population harbored both aromatic ring-hydroxylating-dioxygenase (RHD) gene and AHL/AI-synthetase gene. These bacteria were distributed in 10 orders, 15 families, 42 genus and 78 species. Horizontal transfers of both genes were common among them. Using enrichment and culture dependent method, 6 Sphingomonadales and 4 Rhizobiales with phenanthrene- or pyrene-degrading ability and AHL-production were isolated from marine, wetland and soil samples. Thin-layer-chromatography and gas-chromatography-mass-spectrum revealed that these Sphingomonads produced various AHL molecules. This is the first report of highly diverse bacteria that harbored both aromatics-degrading and QS systems. QS regulation may have broad impacts on aromatics biodegradation, and would be a new angle for developing bioremediation technology.

  1. Characterisation of a marine bacterium Vibrio brasiliensis T33 producing N-acyl homoserine lactone quorum sensing molecules.

    PubMed

    Tan, Wen-Si; Yunos, Nina Yusrina Muhamad; Tan, Pui-Wan; Mohamad, Nur Izzati; Adrian, Tan-Guan-Sheng; Yin, Wai-Fong; Chan, Kok-Gan

    2014-07-08

    N-acylhomoserine lactones (AHL) plays roles as signal molecules in quorum sensing (QS) in most Gram-negative bacteria. QS regulates various physiological activities in relation with population density and concentration of signal molecules. With the aim of isolating marine water-borne bacteria that possess QS properties, we report here the preliminary screening of marine bacteria for AHL production using Chromobacterium violaceum CV026 as the AHL biosensor. Strain T33 was isolated based on preliminary AHL screening and further identified by using 16S rDNA sequence analysis as a member of the genus Vibrio closely related to Vibrio brasiliensis. The isolated Vibrio sp. strain T33 was confirmed to produce N-hexanoyl-L-homoserine lactone (C6-HSL) and N-(3-oxodecanoyl)-L-homoserine lactone (3-oxo-C10 HSL) through high resolution tandem mass spectrometry analysis. We demonstrated that this isolate formed biofilms which could be inhibited by catechin. To the best of our knowledge, this is the first report that documents the production of these AHLs by Vibrio brasiliensis strain T33.

  2. Loss of Social Behaviours in Populations of Pseudomonas aeruginosa Infecting Lungs of Patients with Cystic Fibrosis

    PubMed Central

    Jiricny, Natalie; Molin, Søren; Foster, Kevin; Diggle, Stephen P.; Scanlan, Pauline D.; Ghoul, Melanie; Johansen, Helle Krogh; Santorelli, Lorenzo A.; Popat, Roman; West, Stuart A.; Griffin, Ashleigh S.

    2014-01-01

    Pseudomonas aeruginosa, is an opportunistic, bacterial pathogen causing persistent and frequently fatal infections of the lung in patients with cystic fibrosis. Isolates from chronic infections differ from laboratory and environmental strains in a range of traits and this is widely interpreted as the result of adaptation to the lung environment. Typically, chronic strains carry mutations in global regulation factors that could effect reduced expression of social traits, raising the possibility that competitive dynamics between cooperative and selfish, cheating strains could also drive changes in P. aeruginosa infections. We compared the expression of cooperative traits - biofilm formation, secretion of exo-products and quorum sensing (QS) - in P. aeruginosa isolates that were estimated to have spent different lengths of time in the lung based on clinical information. All three exo-products involved in nutrient acquisition were produced in significantly smaller quantities with increased duration of infection, and patterns across four QS signal molecules were consistent with accumulation over time of mutations in lasR, which are known to disrupt the ability of cells to respond to QS signal. Pyocyanin production, and the proportion of cells in biofilm relative to motile, free-living cells in liquid culture, did not change. Overall, our results confirm that the loss of social behaviour is a consistent trend with time spent in the lung and suggest that social dynamics are potentially relevant to understanding the behaviour of P. aeruginosa in lung infections. PMID:24454693

  3. Trigonella foenum-graceum (Seed) Extract Interferes with Quorum Sensing Regulated Traits and Biofilm Formation in the Strains of Pseudomonas aeruginosa and Aeromonas hydrophila

    PubMed Central

    Husain, Fohad Mabood; Ahmad, Iqbal; Khan, Mohd Shahnawaz; Al-Shabib, Nasser Abdulatif

    2015-01-01

    Trigonella foenum-graecum L. (Fenugreek) is an important plant of the Leguminosae family known to have medicinal properties. However, fraction based antiquorum sensing and antibiofilm activities have not been reported from this plant. In the present study T. foenum-graecum seed extract was sequentially fractionated and sub-MICs were tested for above activities. The methanol fraction of the extract demonstrated significant inhibition of AHL regulated virulence factors: protease, LasB elastase, pyocyanin production, chitinase, EPS, and swarming motility in Pseudomonas aeruginosa PAO1 and PAF79. Further, QS dependent virulence factor in the aquatic pathogen Aeromonas hydrophila WAF38 was also reduced. Application of T. foenum-graecum seed extract to PAO1, PAF79, and WAF38 decreased the biofilm forming abilities of the pathogens by significant levels. The extract also exhibited reduced AHL levels and subsequent downregulation of lasB gene. In vivo study showed an enhanced survival of PAO1-preinfected C. elegans after treatment with extract at 1 mg/mL. Further, the major compound detected by GC-MS, caffeine, reduced the production of QS regulated virulence factors and biofilm at 200 µg/mL concentration indicating its role in the activity of the methanol extract. The results of the present study reveal the potential anti-QS and antibiofilm property of T. foenum-graceum extract and caffeine. PMID:26000026

  4. Inhibition of Bacterial Quorum Sensing by Extracts from Aquatic Fungi: First Report from Marine Endophytes

    PubMed Central

    Martín-Rodríguez, Alberto J.; Reyes, Fernando; Martín, Jesús; Pérez-Yépez, Juan; León-Barrios, Milagros; Couttolenc, Alan; Espinoza, César; Trigos, Ángel; Martín, Víctor S.; Norte, Manuel; Fernández, José J.

    2014-01-01

    In our search for quorum-sensing (QS) disrupting molecules, 75 fungal isolates were recovered from reef organisms (endophytes), saline lakes and mangrove rhizosphere. Their QS inhibitory activity was evaluated in Chromobacterium violaceum CVO26. Four strains of endophytic fungi stood out for their potent activity at concentrations from 500 to 50 μg mL−1. The molecular characterization, based on the internal transcribed spacer (ITS) region sequences (ITS1, 5.8S and ITS2) between the rRNA of 18S and 28S, identified these strains as belonging to four genera: Sarocladium (LAEE06), Fusarium (LAEE13), Epicoccum (LAEE14), and Khuskia (LAEE21). Interestingly, three came from coral species and two of them came from the same organism, the coral Diploria strigosa. Metabolic profiles obtained by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) suggest that a combination of fungal secondary metabolites and fatty acids could be the responsible for the observed activities. The LC-HRMS analysis also revealed the presence of potentially new secondary metabolites. This is, to the best of our knowledge, the first report of QS inhibition by marine endophytic fungi. PMID:25415350

  5. Inhibition of bacterial quorum sensing by extracts from aquatic fungi: first report from marine endophytes.

    PubMed

    Martín-Rodríguez, Alberto J; Reyes, Fernando; Martín, Jesús; Pérez-Yépez, Juan; León-Barrios, Milagros; Couttolenc, Alan; Espinoza, César; Trigos, Angel; Martín, Víctor S; Norte, Manuel; Fernández, José J

    2014-11-19

    In our search for quorum-sensing (QS) disrupting molecules, 75 fungal isolates were recovered from reef organisms (endophytes), saline lakes and mangrove rhizosphere. Their QS inhibitory activity was evaluated in Chromobacterium violaceum CVO26. Four strains of endophytic fungi stood out for their potent activity at concentrations from 500 to 50 μg mL-1. The molecular characterization, based on the internal transcribed spacer (ITS) region sequences (ITS1, 5.8S and ITS2) between the rRNA of 18S and 28S, identified these strains as belonging to four genera: Sarocladium (LAEE06), Fusarium (LAEE13), Epicoccum (LAEE14), and Khuskia (LAEE21). Interestingly, three came from coral species and two of them came from the same organism, the coral Diploria strigosa. Metabolic profiles obtained by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) suggest that a combination of fungal secondary metabolites and fatty acids could be the responsible for the observed activities. The LC-HRMS analysis also revealed the presence of potentially new secondary metabolites. This is, to the best of our knowledge, the first report of QS inhibition by marine endophytic fungi.

  6. CGC/saturation approach: A new impact-parameter-dependent model in the next-to-leading order of perturbative QCD

    NASA Astrophysics Data System (ADS)

    Contreras, Carlos; Levin, Eugene; Meneses, Rodrigo; Potashnikova, Irina

    2016-12-01

    This paper is the first attempt to build a color glass condensate/saturation model based on the next-to-leading-order (NLO) corrections to linear and nonlinear evolution in QCD. We assume that the renormalization scale is the saturation momentum and find that the scattering amplitude has geometric scaling behavior deep in the saturation domain with the explicit formula of this behavior at large τ =r2Qs2. We build a model that includes this behavior, as well as the known ingredients: (i) the behavior of the scattering amplitude in the vicinity of the saturation momentum, using the NLO Balitsky-Fadin-Kuraev-Lipatov kernel, (ii) the pre-asymptotic behavior of ln (Qs2(Y ) ) , as a function of Y , and (iii) the impact parameter behavior of the saturation momentum, which has exponential behavior ∝exp (-m b ) at large b . We demonstrate that the model is able to describe the experimental data for the deep inelastic structure function. Despite this, our model has difficulties that are related to the small value of the QCD coupling at Qs(Y0) and the large values of the saturation momentum, which indicate the theoretical inconsistency of our description.

  7. Efficacies of quorum sensing inhibitors, piericidin A and glucopiericidin A, produced by Streptomyces xanthocidicus KPP01532 for the control of potato soft rot caused by Erwinia carotovora subsp. atroseptica.

    PubMed

    Kang, Ji Eun; Han, Jae Woo; Jeon, Byeong Jun; Kim, Beom Seok

    2016-03-01

    To discover potential inhibitors of the quorum sensing (QS) system, a library of microbial culture extracts was screened with Chromobacterium violaceumCV026 strain. The culture extract of Streptomyces xanthocidicus KPP01532 contained quorum-sensing inhibitors (QSIs) of the CV026 strain. The active constituents of the culture extract of strain KPP01532 were purified using a series of chromatographic procedures, and based on data from NMR and mass spectroscopy, piericidin A and glucopiericidin A were identified. Erwinia carotovora subsp. atroseptica (Eca) is a plant pathogen that causes blackleg and soft rot diseases on potato stems and tubers. The virulence factors of Eca are regulated by QS. The expression of virulence genes (pelC, pehA, celV and nip) under the control of QS was monitored using quantitative real-time PCR (qRT-PCR). The transcription levels of the four genes were significantly lower when Eca was exposed to piericidin A or glucopiericidin A. These two compounds displayed similar control efficacies against soft rot caused by Eca in potato slices as furanone C-30. Therefore, piericidin A and glucopiericidin A are potential QSIs that suppress the expression of the virulence genes of Eca, suggesting that they could have potential use as control agents of soft rot disease on potato tubers.

  8. Expedient construction of small molecule macroarrays via sequential palladium- and copper-mediated reactions and their ex situ biological testing†

    PubMed Central

    Frei, Reto; Breitbach, Anthony S.

    2012-01-01

    We report the highly efficient syntheses of a series of focused libraries in the small molecule macroarray format using Suzuki–Miyaura and copper-catalyzed azide–alkyne cycloaddition (or “click”) reactions. The libraries were based on stilbene and triazole scaffolds, which are known to have a broad range of biological activities, including quorum-sensing (QS) modulation in bacteria. The library products were generated in parallel on the macroarray in extremely short reaction times (~10–20 min) and isolated in excellent purities. Biological testing of one macroarray library post-cleavage (ex situ) revealed several potent agonists of the QS receptor, LuxR, in Vibrio fischeri. These synthetic agonists, in contrast to others that we have reported, were only active in the presence of the native QS signal in V. fischeri, which is suggestive of a different mode of activity. Notably, the results presented herein showcase the ready compatibility of the macroarray platform with chemical reactions that are commonly utilized in small molecule probe and drug discovery today. As such, this work serves to expand the utility of the small molecule macroarray as a rapid and operationally straightforward approach toward the synthesis and screening of bioactive agents. PMID:23198087

  9. Absorption and modulus measurements in the seismic frequency and strain range on partially saturated sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Paffenholz, Josef; Burkhardt, Hans

    1989-07-01

    The absorptions 1/QE and 1/QS of partially water-saturated sedimentary rocks were determined from phase differences between stress and strain for longitudinal deformation frequencies between 0.03 and 300 Hz and torsional frequencies between 0.03 and 100 Hz. Both longitudinal and shear strain amplitudes were of the order of 10-6. For water saturation between 0 and 50%, Young's moduli and shear moduli were shown to decrease with increasing saturation. In this saturation range both 1/QE and 1/QS increased, but no distinguishable absorption maxima were observed. For saturation percentages greater than 50%, the moduli of the samples appeared independent of the water content. 1/QE increased until full saturation and showed a strong frequency dependence. 1/QS is much less affected by increasing water saturation and has no absorption maxima in general. Since the absorption and the moduli reduction show different saturation dependencies, two different mechanisms for these effects are proposed. The addition of water changes the interaction force between the molecules on opposite walls of thin cracks. This provides a mechanism for the modulus reduction. Calculations based on the Biot-Gardner theory (Gardner, 1962) indicate that part of the observed absorption may be caused by fluid flow due to the limited sample size as proposed by White (1986). Fluid-supported thermorelaxation is proposed, as a possible intrinsic absorption mechanism.

  10. Peptide pheromone signaling in Streptococcus and Enterococcus

    PubMed Central

    Cook, Laura C.; Federle, Michael J.

    2014-01-01

    Intercellular chemical signaling in bacteria, commonly referred to as quorum sensing (QS), relies on the production and detection of compounds known as pheromones to elicit coordinated responses among members of a community. Pheromones produced by Gram-positive bacteria are comprised of small peptides. Based on both peptide structure and sensory system architectures, Gram-positive bacterial signaling pathways may be classified into one of four groups with a defining hallmark: cyclical peptides of the Agr type, peptides that contain Gly-Gly processing motifs, sensory systems of the RNPP family, or the recently characterized Rgg-like regulatory family. The recent discovery that Rgg family members respond to peptide pheromones increases substantially the number of species in which QS is likely a key regulatory component. These pathways control a variety of fundamental behaviors including conjugation, natural competence for transformation, biofilm development, and virulence factor regulation. Overlapping QS pathways found in multiple species and pathways that utilize conserved peptide pheromones provide opportunities for interspecies communication. Here we review pheromone signaling identified in the genera Enterococcus and Streptococcus, providing examples of all four types of pathways. PMID:24118108

  11. Loss of social behaviours in populations of Pseudomonas aeruginosa infecting lungs of patients with cystic fibrosis.

    PubMed

    Jiricny, Natalie; Molin, Søren; Foster, Kevin; Diggle, Stephen P; Scanlan, Pauline D; Ghoul, Melanie; Johansen, Helle Krogh; Santorelli, Lorenzo A; Popat, Roman; West, Stuart A; Griffin, Ashleigh S

    2014-01-01

    Pseudomonas aeruginosa, is an opportunistic, bacterial pathogen causing persistent and frequently fatal infections of the lung in patients with cystic fibrosis. Isolates from chronic infections differ from laboratory and environmental strains in a range of traits and this is widely interpreted as the result of adaptation to the lung environment. Typically, chronic strains carry mutations in global regulation factors that could effect reduced expression of social traits, raising the possibility that competitive dynamics between cooperative and selfish, cheating strains could also drive changes in P. aeruginosa infections. We compared the expression of cooperative traits - biofilm formation, secretion of exo-products and quorum sensing (QS) - in P. aeruginosa isolates that were estimated to have spent different lengths of time in the lung based on clinical information. All three exo-products involved in nutrient acquisition were produced in significantly smaller quantities with increased duration of infection, and patterns across four QS signal molecules were consistent with accumulation over time of mutations in lasR, which are known to disrupt the ability of cells to respond to QS signal. Pyocyanin production, and the proportion of cells in biofilm relative to motile, free-living cells in liquid culture, did not change. Overall, our results confirm that the loss of social behaviour is a consistent trend with time spent in the lung and suggest that social dynamics are potentially relevant to understanding the behaviour of P. aeruginosa in lung infections.

  12. Real-time monitoring of quorum sensing in 3D-printed bacterial aggregates using scanning electrochemical microscopy.

    PubMed

    Connell, Jodi L; Kim, Jiyeon; Shear, Jason B; Bard, Allen J; Whiteley, Marvin

    2014-12-23

    Microbes frequently live in nature as small, densely packed aggregates containing ∼10(1)-10(5) cells. These aggregates not only display distinct phenotypes, including resistance to antibiotics, but also, serve as building blocks for larger biofilm communities. Aggregates within these larger communities display nonrandom spatial organization, and recent evidence indicates that this spatial organization is critical for fitness. Studying single aggregates as well as spatially organized aggregates remains challenging because of the technical difficulties associated with manipulating small populations. Micro-3D printing is a lithographic technique capable of creating aggregates in situ by printing protein-based walls around individual cells or small populations. This 3D-printing strategy can organize bacteria in complex arrangements to investigate how spatial and environmental parameters influence social behaviors. Here, we combined micro-3D printing and scanning electrochemical microscopy (SECM) to probe quorum sensing (QS)-mediated communication in the bacterium Pseudomonas aeruginosa. Our results reveal that QS-dependent behaviors are observed within aggregates as small as 500 cells; however, aggregates larger than 2,000 bacteria are required to stimulate QS in neighboring aggregates positioned 8 μm away. These studies provide a powerful system to analyze the impact of spatial organization and aggregate size on microbial behaviors.

  13. Label-free molecular imaging of bacterial communities of the opportunistic pathogen Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Baig, Nameera; Polisetti, Sneha; Morales-Soto, Nydia; Dunham, Sage J. B.; Sweedler, Jonathan V.; Shrout, Joshua D.; Bohn, Paul W.

    2016-09-01

    Biofilms, such as those formed by the opportunistic human pathogen Pseudomonas aeruginosa are complex, matrix enclosed, and surface-associated communities of cells. Bacteria that are part of a biofilm community are much more resistant to antibiotics and the host immune response than their free-floating counterparts. P. aeruginosa biofilms are associated with persistent and chronic infections in diseases such as cystic fibrosis and HIV-AIDS. P. aeruginosa synthesizes and secretes signaling molecules such as the Pseudomonas quinolone signal (PQS) which are implicated in quorum sensing (QS), where bacteria regulate gene expression based on population density. Processes such as biofilms formation and virulence are regulated by QS. This manuscript describes the powerful molecular imaging capabilities of confocal Raman microscopy (CRM) and surface enhanced Raman spectroscopy (SERS) in conjunction with multivariate statistical tools such as principal component analysis (PCA) for studying the spatiotemporal distribution of signaling molecules, secondary metabolites and virulence factors in biofilm communities of P. aeruginosa. Our observations reveal that the laboratory strain PAO1C synthesizes and secretes 2-alkyl-4-hydroxyquinoline N-oxides and 2-alkyl-4-hydroxyquinolones in high abundance, while the isogenic acyl homoserine lactone QS-deficient mutant (ΔlasIΔrhlI) strain produces predominantly 2-alkyl-quinolones during biofilm formation. This study underscores the use of CRM, along with traditional biological tools such as genetics, for studying the behavior of microbial communities at the molecular level.

  14. MS Based Metabonomics

    SciTech Connect

    Want, Elizabeth J.; Metz, Thomas O.

    2010-03-01

    Metabonomics is the latest and least mature of the systems biology triad, which also includes genomics and proteomics, and has its origins in the early orthomolecular medicine work pioneered by Linus Pauling and Arthur Robinson. It was defined by Nicholson and colleagues in 1999 as the quantitative measurement of perturbations in the metabolite complement of an integrated biological system in response to internal or external stimuli, and is often used today to describe many non-global types of metabolite analyses. Applications of metabonomics are extensive and include toxicology, nutrition, pharmaceutical research and development, physiological monitoring and disease diagnosis. For example, blood samples from millions of neonates are tested routinely by mass spectrometry (MS) as a diagnostic tool for inborn errors of metabolism. The metabonome encompasses a wide range of structurally diverse metabolites; therefore, no single analytical platform will be sufficient. Specialized sample preparation and detection techniques are required, and advances in NMR and MS technologies have led to enhanced metabonome coverage, which in turn demands improved data analysis approaches. The role of MS in metabonomics is still evolving as instrumentation and software becomes more sophisticated and as researchers realize the strengths and limitations of current technology. MS offers a wide dynamic range, high sensitivity, and reproducible, quantitative analysis. These attributes are essential for addressing the challenges of metabonomics, as the range of metabolite concentrations easily exceeds nine orders of magnitude in biofluids, and the diversity of molecular species ranges from simple amino and organic acids to lipids and complex carbohydrates. Additional challenges arise in generating a comprehensive metabolite profile, downstream data processing and analysis, and structural characterization of important metabolites. A typical workflow of MS-based metabonomics is shown in Figure

  15. 3. SOUTH SIDE. Edwards Air Force Base, South Base ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SOUTH SIDE. - Edwards Air Force Base, South Base Sled Track, Firing & Control Blockhouse for 10,000-foot Track, South of Sled Track at midpoint of 20,000-foot track, Lancaster, Los Angeles County, CA

  16. Knowledge based question answering

    SciTech Connect

    Pazzani, M.J.; Engelman, C.

    1983-01-01

    The natural language database query system incorporated in the Knobs Interactive Planning System comprises a dictionary driven parser, APE-II, and script interpreter whch yield a conceptual dependency as a representation of the meaning of user input. A conceptualisation pattern matching production system then determines and executes a procedure for extracting the desired information from the database. In contrast to syntax driven q-a systems, e.g. those based on atn parsers, APE-II is driven bottom-up by expectations associated with word meanings. The goals of this approach include utilising similar representations for questions with similar meanings but widely varying surface structures, developing a powerful mechanism for the disambiguation of words with multiple meanings and the determination of pronoun referents, answering questions which require inferences to be understood, and interpreting ellipses and ungrammatical statements. The Knobs demonstration system is an experimental, expert system for air force mission planning applications. 16 refs.

  17. Liaison based assembly design

    SciTech Connect

    Ames, A.; Kholwadwala, D.; Wilson, R.H.

    1996-12-01

    Liaison Based Assembly Design extends the current information infrastructure to support design in terms of kinematic relationships between parts, or liaisons. These liaisons capture information regarding contact, degrees-of-freedom constraints and containment relationships between parts in an assembly. The project involved defining a useful collection of liaison representations, investigating their properties, and providing for maximum use of the data in downstream applications. We tested our ideas by implementing a prototype system involving extensions to Pro/Engineer and the Archimedes assembly planner. With an expanded product model, the design system is more able to capture design intent. When a product update is attempted, increased knowledge availability improves our ability to understand the effect of design changes. Manufacturing and analysis disciplines benefit from having liaison information available, so less time is wasted arguing over incomplete design specifications and our enterprise can be more completely integrated.

  18. DNA based molecular motors

    NASA Astrophysics Data System (ADS)

    Michaelis, Jens; Muschielok, Adam; Andrecka, Joanna; Kügel, Wolfgang; Moffitt, Jeffrey R.

    2009-12-01

    Most of the essential cellular processes such as polymerisation reactions, gene expression and regulation are governed by mechanical processes. Controlled mechanical investigations of these processes are therefore required in order to take our understanding of molecular biology to the next level. Single-molecule manipulation and force spectroscopy have over the last 15 years been developed into extremely powerful techniques. Applying these techniques to the investigation of proteins and DNA molecules has led to a mechanistic understanding of protein function on the level of single molecules. As examples for DNA based molecular machines we will describe single-molecule experiments on RNA polymerases as well as on the packaging of DNA into a viral capsid-a process that is driven by one of the most powerful molecular motors.

  19. Base isolation: Fresh insight

    SciTech Connect

    Shustov, V.

    1993-07-15

    The objective of the research is a further development of the engineering concept of seismic isolation. Neglecting the transient stage of seismic loading results in a widespread misjudgement: The force of resistance associated with velocity is mostly conceived as a source of damping vibrations, though it is an active force at the same time, during an earthquake type excitation. For very pliant systems such as base isolated structures with relatively low bearing stiffness and with artificially added heavy damping mechanism, the so called `damping`` force may occur even the main pushing force at an earthquake. Thus, one of the two basic pillars of the common seismic isolation philosophy, namely, the doctrine of usefulness and necessity of a strong damping mechanism, is turning out to be a self-deception, sometimes even jeopardizing the safety of structures and discrediting the very idea of seismic isolation. There is a way out: breaking with damping dependancy.

  20. Ferroelectrics based absorbing layers

    NASA Astrophysics Data System (ADS)

    Hao, Jianping; Sadaune, Véronique; Burgnies, Ludovic; Lippens, Didier

    2014-07-01

    We show that ferroelectrics-based periodic structure made of BaSrTiO3 (BST) cubes, arrayed onto a metal plate with a thin dielectric spacer film exhibit a dramatic enhancement of absorbance with value close to unity. The enhancement is found around the Mie magnetic resonance of the Ferroelectrics cubes with the backside metal layer stopping any transmitted waves. It also involves quasi-perfect impedance matching resulting in reflection suppression via simultaneous magnetic and electrical activities. In addition, it was shown numerically the existence of a periodicity optimum, which is explained from surface waves analysis along with trade-off between the resonance damping and the intrinsic loss of ferroelectrics cubes. An experimental verification in a hollow waveguide configuration with a good comparison with full-wave numerical modelling is at last reported by measuring the scattering parameters of single and dual BST cubes schemes pointing out coupling effects for densely packed structures.

  1. Information-based clustering

    PubMed Central

    Slonim, Noam; Atwal, Gurinder Singh; Tkačik, Gašper; Bialek, William

    2005-01-01

    In an age of increasingly large data sets, investigators in many different disciplines have turned to clustering as a tool for data analysis and exploration. Existing clustering methods, however, typically depend on several nontrivial assumptions about the structure of data. Here, we reformulate the clustering problem from an information theoretic perspective that avoids many of these assumptions. In particular, our formulation obviates the need for defining a cluster “prototype,” does not require an a priori similarity metric, is invariant to changes in the representation of the data, and naturally captures nonlinear relations. We apply this approach to different domains and find that it consistently produces clusters that are more coherent than those extracted by existing algorithms. Finally, our approach provides a way of clustering based on collective notions of similarity rather than the traditional pairwise measures. PMID:16352721

  2. Covariant mutually unbiased bases

    NASA Astrophysics Data System (ADS)

    Carmeli, Claudio; Schultz, Jussi; Toigo, Alessandro

    2016-06-01

    The connection between maximal sets of mutually unbiased bases (MUBs) in a prime-power dimensional Hilbert space and finite phase-space geometries is well known. In this article, we classify MUBs according to their degree of covariance with respect to the natural symmetries of a finite phase-space, which are the group of its affine symplectic transformations. We prove that there exist maximal sets of MUBs that are covariant with respect to the full group only in odd prime-power dimensional spaces, and in this case, their equivalence class is actually unique. Despite this limitation, we show that in dimension 2r covariance can still be achieved by restricting to proper subgroups of the symplectic group, that constitute the finite analogues of the oscillator group. For these subgroups, we explicitly construct the unitary operators yielding the covariance.

  3. Surface Plasmon Based Spectrometer

    NASA Astrophysics Data System (ADS)

    Wig, Andrew; Passian, Ali; Boudreaux, Philip; Ferrell, Tom

    2008-03-01

    A spectrometer that uses surface plasmon excitation in thin metal films to separate light into its component wavelengths is described. The use of surface plasmons as a dispersive medium sets this spectrometer apart from prism, grating, and interference based variants and allows for the miniaturization of this device. Theoretical and experimental results are presented for two different operation models. In the first case surface plasmon tunneling in the near field is used to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution as well as absorption spectra of chlorophyll extracted from a spinach leaf. The second model looks at the far field components of surface plasmon scattering.

  4. Race-based therapeutics.

    PubMed

    Yancy, Clyde W

    2008-08-01

    The issue of race in medicine is problematic. Race is not a physiologic grouping, and all persons of a given race do not necessarily share the same clinical phenotype or genetic substrate. Despite clear signals that certain risk factors and diseases vary as a function of race, translating those differences into race-based therapeutics has been awkward and has done little to change the natural history of cardiovascular disease as it affects special populations. Among the varied special populations, the African American population appears to have the most significant and adverse variances for cardiovascular disease as well as worrisome signals that drug responsiveness varies. Recent guideline statements have now acknowledged certain treatment options that are most appropriate for African Americans with cardiovascular disease, especially hypertension and heart failure. As more physiologic markers of disease and drug responsiveness become available, the need for racial designations in medicine may lessen, and therapies can be optimized for all patients without regard to race or ethnicity.

  5. Base Research Program

    SciTech Connect

    Everett Sondreal; John Hendrikson

    2009-03-31

    In June 2009, the Energy & Environmental Research Center (EERC) completed 11 years of research under the U.S. Department of Energy (DOE) Base Cooperative Agreement No. DE-FC26-98FT40320 funded through the Office of Fossil Energy (OFE) and administered at the National Energy Technology Laboratory (NETL). A wide range of diverse research activities were performed under annual program plans approved by NETL in seven major task areas: (1) resource characterization and waste management, (2) air quality assessment and control, (3) advanced power systems, (4) advanced fuel forms, (5) value-added coproducts, (6) advanced materials, and (7) strategic studies. This report summarizes results of the 67 research subtasks and an additional 50 strategic studies. Selected highlights in the executive summary illustrate the contribution of the research to the energy industry in areas not adequately addressed by the private sector alone. During the period of performance of the agreement, concerns have mounted over the impact of carbon emissions on climate change, and new programs have been initiated by DOE to ensure that fossil fuel resources along with renewable resources can continue to supply the nation's transportation fuel and electric power. The agreement has addressed DOE goals for reductions in CO{sub 2} emissions through efficiency, capture, and sequestration while expanding the supply and use of domestic energy resources for energy security. It has further contributed to goals for near-zero emissions from highly efficient coal-fired power plants; environmental control capabilities for SO{sub 2}, NO{sub x}, fine respirable particulate (PM{sub 2.5}), and mercury; alternative transportation fuels including liquid synfuels and hydrogen; and synergistic integration of fossil and renewable resources (e.g., wind-, biomass-, and coal-based electrical generation).

  6. Loyalty-based management.

    PubMed

    Reichheld, F F

    1993-01-01

    Despite a flurry of activities aimed at serving customers better, few companies have systematically revamped their operations with customer loyalty in mind. Instead, most have adopted improvement programs ad hoc, and paybacks haven't materialized. Building a highly loyal customer base must be integral to a company's basic business strategy. Loyalty leaders like MBNA credit cards are successful because they have designed their entire business systems around customer loyalty--a self-reinforcing system in which the company delivers superior value consistently and reinvents cash flows to find and keep high-quality customers and employees. The economic benefits of high customer loyalty are measurable. When a company consistently delivers superior value and wins customer loyalty, market share and revenues go up, and the cost of acquiring new customers goes down. The better economics mean the company can pay workers better, which sets off a whole chain of events. Increased pay boosts employee moral and commitment; as employees stay longer, their productivity goes up and training costs fall; employees' overall job satisfaction, combined with their experience, helps them serve customers better; and customers are then more inclined to stay loyal to the company. Finally, as the best customers and employees become part of the loyalty-based system, competitors are left to survive with less desirable customers and less talented employees. To compete on loyalty, a company must understand the relationships between customer retention and the other parts of the business--and be able to quantify the linkages between loyalty and profits. It involves rethinking and aligning four important aspects of the business: customers, product/service offering, employees, and measurement systems.

  7. Electrical percolation based biosensors.

    PubMed

    Bruck, Hugh Alan; Yang, Minghui; Kostov, Yordan; Rasooly, Avraham

    2013-10-01

    A new approach to label free biosensing has been developed based on the principle of "electrical percolation". In electrical percolation, long-range electrical connectivity is formed in randomly oriented and distributed systems of discrete elements. By applying this principle to biological interactions, it is possible to measure biological components both directly and electronically. The main element for electrical percolation biosensor is the biological semiconductor (BSC) which is a multi-layer 3-D carbon nanotube-antibody network. In the BSC, molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. BSCs can be fabricated by immobilizing conducting elements, such as pre-functionalized single-walled carbon nanotubes (SWNTs)-antibody complex, directly onto a substrate, such as a Poly(methyl methacrylate) (PMMA) surface (also known as plexi-glass or Acrylic). BSCs have been demonstrated for direct (label-free) electronic measurements of antibody-antigen binding using SWNTs. If the concentration of the SWNT network is slightly above the electrical percolation threshold, then binding of a specific antigen to the pre-functionalized SWNT dramatically increases the electrical resistance due to changes in the tunneling between the SWNTs. Using anti-staphylococcal enterotoxin B (SEB) IgG as a "gate" and SEB as an "actuator", it was demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/ml. Based on this concept, an automated configuration for BSCs is described here that enables real time continuous detection. The new BSC configuration may permit assembly of multiple sensors on the same chip to create "biological central processing units (CPUs)" with multiple biological elements, capable of processing and sorting out information on multiple analytes simultaneously.

  8. PROcess Based Diagnostics PROBE

    NASA Technical Reports Server (NTRS)

    Clune, T.; Schmidt, G.; Kuo, K.; Bauer, M.; Oloso, H.

    2013-01-01

    Many of the aspects of the climate system that are of the greatest interest (e.g., the sensitivity of the system to external forcings) are emergent properties that arise via the complex interplay between disparate processes. This is also true for climate models most diagnostics are not a function of an isolated portion of source code, but rather are affected by multiple components and procedures. Thus any model-observation mismatch is hard to attribute to any specific piece of code or imperfection in a specific model assumption. An alternative approach is to identify diagnostics that are more closely tied to specific processes -- implying that if a mismatch is found, it should be much easier to identify and address specific algorithmic choices that will improve the simulation. However, this approach requires looking at model output and observational data in a more sophisticated way than the more traditional production of monthly or annual mean quantities. The data must instead be filtered in time and space for examples of the specific process being targeted.We are developing a data analysis environment called PROcess-Based Explorer (PROBE) that seeks to enable efficient and systematic computation of process-based diagnostics on very large sets of data. In this environment, investigators can define arbitrarily complex filters and then seamlessly perform computations in parallel on the filtered output from their model. The same analysis can be performed on additional related data sets (e.g., reanalyses) thereby enabling routine comparisons between model and observational data. PROBE also incorporates workflow technology to automatically update computed diagnostics for subsequent executions of a model. In this presentation, we will discuss the design and current status of PROBE as well as share results from some preliminary use cases.

  9. Problem-Based Learning in Web-Based Science Classroom.

    ERIC Educational Resources Information Center

    Kim, Heeyoung; Chung, Ji-Sook; Kim, Younghoon

    The purpose of this paper is to discuss how general problem-based learning (PBL) models and social-constructivist perspectives are applied to the design and development of a Web-based science program, which emphasizes inquiry-based learning for fifth grade students. The paper also deals with the general features and learning process of a Web-based…

  10. Local and Global Consequences of Flow on Bacterial Quorum Sensing

    PubMed Central

    Kim, Minyoung Kevin; Ingremeau, Francois; Zhao, Aishan; Bassler, Bonnie L.; Stone, Howard A.

    2016-01-01

    Bacteria use a chemical communication process called quorum sensing (QS) to control collective behaviours, such as pathogenesis and biofilm formation1,2. QS relies on the production, release, and group-wide detection of signal molecules called autoinducers. To date, studies of bacterial pathogenesis in well-mixed cultures have revealed virulence factors and the regulatory circuits controlling them, including the overarching role of QS3. Although flow is ubiquitous to nearly all living systems4, much less explored is how QS influences pathogenic traits in scenarios that mimic host environments, for example, under fluid flow and in complex geometries. Previous studies have showed that sufficiently strong flow represses QS5–7. Nonetheless, it is not known how QS functions under constant or intermittent flow, how it varies within biofilms or as a function of position along a confined flow, or how surface topography (grooves, crevices, pores) influence QS-mediated communication. We explore these questions using two common pathogens Staphylococcus aureus and Vibrio cholerae. We identify conditions where flow represses QS and other conditions where QS is activated despite flow, including characterizing geometric and topographic features that influence the QS response. Our studies highlight that, under flow, genetically identical cells do not exhibit phenotypic uniformity with respect to QS in space and time, leading to complex patterns of pathogenesis and colonization. Understanding the ramifications of spatially and temporally non-uniform QS responses in realistic environments will be crucial for successful deployment of synthetic pro- and anti-QS strategies. PMID:27571752

  11. Performance-Based Funding Brief

    ERIC Educational Resources Information Center

    Washington Higher Education Coordinating Board, 2011

    2011-01-01

    A number of states have made progress in implementing performance-based funding (PFB) and accountability. This policy brief summarizes main features of performance-based funding systems in three states: Tennessee, Ohio, and Indiana. The brief also identifies key issues that states considering performance-based funding must address, as well as…

  12. Neighborhood-Based Family Support.

    ERIC Educational Resources Information Center

    Downs, Susan Whitelaw

    This report provides an overview of neighborhood-based family-support programs and describes the development of the family-support movement. It includes sections on the definition of neighborhood-based family-support programs, the principles and theories on which they are based, a discussion of the problems they are designed to address, a…

  13. Mentalization-Based Treatment

    PubMed Central

    Bateman, Anthony; Fonagy, Peter

    2013-01-01

    The concept of mentalizing has captured the interest and imagination of an astonishing range of people—from psychoanalysts to neuroscientists, from child development researchers to geneticists, from existential philosophers to phenomenologists—all of whom seem to have found it useful. According to the Thompson Reuter maintained Web of Science, the use of the term in titles and abstracts of scientific papers increased from 10 to 2,750 between 1991 and 2011. Clinicians in particular have enthusiastically embraced the idea, and have put it to innovative use in their practices. Mentalization-based treatment (MBT)—making mentalizing a core focus of therapy—was initially developed for the treatment of borderline personality disorder (BPD) in routine clinical services delivered in group and individual modalities. Therapy with mentalizing as a central component is currently being developed for treatment of numerous groups, including people with antisocial personality disorder, substance abuse, eating disorders, and at-risk mothers with infants and children (A. Bateman & Fonagy, 2011). It is also being used with families and adolescents, in schools, and in managing social groups (Asen & Fonagy, 2011; Fonagy et al., 2009; Twemlow, Fonagy, & Sacco, 2005a, 2005b). In this article, we focus on MBT in the treatment of BPD. PMID:26157198

  14. Microsphere based saliva diagnostics

    NASA Astrophysics Data System (ADS)

    Rissin, David M.; DiCesare, Christopher; Hayman, Ryan B.; Blicharz, Timothy M.; Walt, David R.

    2005-11-01

    Saliva presents a minimally invasive alternative medium to blood for performing diagnostics1. Microsphere sensors for ions, small organic molecules, and proteins are currently being developed and optical microarrays containing thousands of these sensors will be used for simultaneous multi-analyte analysis. The fiber bundle platform in use is 1mm in diameter and contains approximately 50,000 individually addressable 3.1μm fibers, each with an etched well capable of housing a single 3.1μm microsphere sensor. Micron-sized bead-based chemistries are produced in house, followed by deposition onto a fiber-optic bundle platform, allowing for multiplexed analysis. The ultimate goal is to develop a universal diagnostic system using saliva as the diagnostic medium. This platform will permit multiplexed analysis of a sample by integrating microfluidics with the optical arrays loaded with sensors capable of detecting relevant biomarkers associated with a wide range of disease states. Disease states that are currently under investigation include end stage renal disease (ESRD) and Sjoegrens Syndrome (SS).

  15. Alphavirus-Based Vaccines

    PubMed Central

    Lundstrom, Kenneth

    2014-01-01

    Alphavirus vectors have demonstrated high levels of transient heterologous gene expression both in vitro and in vivo and, therefore, possess attractive features for vaccine development. The most commonly used delivery vectors are based on three single-stranded encapsulated alphaviruses, namely Semliki Forest virus, Sindbis virus and Venezuelan equine encephalitis virus. Alphavirus vectors have been applied as replication-deficient recombinant viral particles and, more recently, as replication-proficient particles. Moreover, in vitro transcribed RNA, as well as layered DNA vectors have been applied for immunization. A large number of highly immunogenic viral structural proteins expressed from alphavirus vectors have elicited strong neutralizing antibody responses in multispecies animal models. Furthermore, immunization studies have demonstrated robust protection against challenges with lethal doses of virus in rodents and primates. Similarly, vaccination with alphavirus vectors expressing tumor antigens resulted in prophylactic protection against challenges with tumor-inducing cancerous cells. As certain alphaviruses, such as Chikungunya virus, have been associated with epidemics in animals and humans, attention has also been paid to the development of vaccines against alphaviruses themselves. Recent progress in alphavirus vector development and vaccine technology has allowed conducting clinical trials in humans. PMID:24937089

  16. Constraint-based scheduling

    NASA Technical Reports Server (NTRS)

    Zweben, Monte

    1991-01-01

    The GERRY scheduling system developed by NASA Ames with assistance from the Lockheed Space Operations Company, and the Lockheed Artificial Intelligence Center, uses a method called constraint based iterative repair. Using this technique, one encodes both hard rules and preference criteria into data structures called constraints. GERRY repeatedly attempts to improve schedules by seeking repairs for violated constraints. The system provides a general scheduling framework which is being tested on two NASA applications. The larger of the two is the Space Shuttle Ground Processing problem which entails the scheduling of all inspection, repair, and maintenance tasks required to prepare the orbiter for flight. The other application involves power allocations for the NASA Ames wind tunnels. Here the system will be used to schedule wind tunnel tests with the goal of minimizing power costs. In this paper, we describe the GERRY system and its applications to the Space Shuttle problem. We also speculate as to how the system would be used for manufacturing, transportation, and military problems.

  17. Constraint-based scheduling

    NASA Technical Reports Server (NTRS)

    Zweben, Monte

    1991-01-01

    The GERRY scheduling system developed by NASA Ames with assistance from the Lockheed Space Operations Company, and the Lockheed Artificial Intelligence Center, uses a method called constraint-based iterative repair. Using this technique, one encodes both hard rules and preference criteria into data structures called constraints. GERRY repeatedly attempts to improve schedules by seeking repairs for violated constraints. The system provides a general scheduling framework which is being tested on two NASA applications. The larger of the two is the Space Shuttle Ground Processing problem which entails the scheduling of all the inspection, repair, and maintenance tasks required to prepare the orbiter for flight. The other application involves power allocation for the NASA Ames wind tunnels. Here the system will be used to schedule wind tunnel tests with the goal of minimizing power costs. In this paper, we describe the GERRY system and its application to the Space Shuttle problem. We also speculate as to how the system would be used for manufacturing, transportation, and military problems.

  18. Lunar base construction requirements

    NASA Technical Reports Server (NTRS)

    Jolly, Steve; Helleckson, Brent

    1990-01-01

    The following viewgraph presentation is a review of the Lunar Base Constructibility Study carried out in the spring and summer of 1990. The objective of the study was to develop a method for evaluating the constructibility of Phase A proposals to build facilities on orbit or on extraterrestrial surfaces. Space construction was broadly defined as all forms of assembly, disassembly, connection, disconnection, deployment, stowage, excavation, emplacement, activation, test, transportation, etc., required to create facilities in orbit and on the surfaces of other celestial bodies. It was discovered that decisions made in the face of stated and unstated assumptions early in the design process (commonly called Phase A) can lock in non-optimal construction methods. Often, in order to construct the design, alterations must be made to the design during much later phases of the project. Such 'fixes' can be very difficult, expensive, or perhaps impossible. Assessing constructibility should thus be a part of the iterative design process, starting with the Phase A studies and continuing through production. This study assumes that there exists a minimum set of key construction requirements (i.e., questions whose answers form the set of discriminators) that must be implied or specified in order to assess the constructibility of the design. This set of construction requirements constitutes a 'constructibility filter' which then becomes part of the iterative design process. Five inherently different, dichotomous design reference missions were used in the extraction of these requirements to assure the depth and breath of the list.

  19. Mobile robot knowledge base

    NASA Astrophysics Data System (ADS)

    Heath Pastore, Tracy; Barnes, Mitchell; Hallman, Rory

    2005-05-01

    Robot technology is developing at a rapid rate for both commercial and Department of Defense (DOD) applications. As a result, the task of managing both technology and experience information is growing. In the not-to-distant past, tracking development efforts of robot platforms, subsystems and components was not too difficult, expensive, or time consuming. To do the same today is a significant undertaking. The Mobile Robot Knowledge Base (MRKB) provides the robotics community with a web-accessible, centralized resource for sharing information, experience, and technology to more efficiently and effectively meet the needs of the robot system user. The resource includes searchable information on robot components, subsystems, mission payloads, platforms, and DOD robotics programs. In addition, the MRKB website provides a forum for technology and information transfer within the DOD robotics community and an interface for the Robotic Systems Pool (RSP). The RSP manages a collection of small teleoperated and semi-autonomous robotic platforms, available for loan to DOD and other qualified entities. The objective is to put robots in the hands of users and use the test data and fielding experience to improve robot systems.

  20. Lunar base heat pump

    NASA Technical Reports Server (NTRS)

    Goldman, Jeffrey H.; Tetreault, R.; Fischbach, D.; Walker, D.

    1994-01-01

    A heat pump is a device which elevates the temperature of a heat flow by a means of an energy input. By doing this, the heat pump can cause heat to transfer faster from a warm region to a cool region, or it can cause heat to flow from a cool region to a warmer region. The second case is the one which finds vast commercial applications such as air conditioning, heating, and refrigeration. Aerospace applications of heat pumps include both cases. The NASA Johnson Space Center is currently developing a Life Support Systems Integration Facility (LSSIF, previously SIRF) to provide system-level integration, operational test experience, and performance data that will enable NASA to develop flight-certified hardware for future planetary missions. A high lift heat pump is a significant part of the TCS hardware development associated with the LSSIF. The high lift heat pump program discussed here is being performed in three phases. In Phase 1, the objective is to develop heat pump concepts for a lunar base, a lunar lander, and for a ground development unit for the SIRF. In Phase 2, the design of the SIRF ground test unit is being performed, including identification and evaluation of safety and reliability issues. In Phase 3, the SIRF unit will be manufactured, tested, and delivered to the NASA Johnson Space Center.

  1. Graphene based GHz detectors

    NASA Astrophysics Data System (ADS)

    Boyd, Anthony K.; El Fatimy, Abdel; Barbara, Paola; Nath, Anindya; Campbell, Paul M.; Myers-Ward, Rachael; Daniels, Kevin; Gaskill, D. Kurt

    Graphene demonstrates great promise as a detector over a wide spectral range especially in the GHz range. This is because absorption is enhanced due to the Drude contribution. In the GHz range there are viable detection mechanisms for graphene devices. With this in mind, two types of GHz detectors are fabricated on epitaxial graphene using a lift off resist-based clean lithography process to produce low contact resistance. Both device types use asymmetry for detection, consistent with recent thoughts of the photothermoelectric effect (PTE) mechanism. The first is an antenna coupled device. It utilizes two dissimilar contact metals and the work function difference produces the asymmetry. The other device is a field effect transistor constructed with an asymmetric top gate that creates a PN junction and facilitates tuning the photovoltaic response. The response of both device types, tested from 100GHz to 170GHz, are reported. This work was sponsored by the U.S. Office of Naval Research (Award Number N000141310865).

  2. Alphavirus-based vaccines.

    PubMed

    Lundstrom, Kenneth

    2014-06-16

    Alphavirus vectors have demonstrated high levels of transient heterologous gene expression both in vitro and in vivo and, therefore, possess attractive features for vaccine development. The most commonly used delivery vectors are based on three single-stranded encapsulated alphaviruses, namely Semliki Forest virus, Sindbis virus and Venezuelan equine encephalitis virus. Alphavirus vectors have been applied as replication-deficient recombinant viral particles and, more recently, as replication-proficient particles. Moreover, in vitro transcribed RNA, as well as layered DNA vectors have been applied for immunization. A large number of highly immunogenic viral structural proteins expressed from alphavirus vectors have elicited strong neutralizing antibody responses in multispecies animal models. Furthermore, immunization studies have demonstrated robust protection against challenges with lethal doses of virus in rodents and primates. Similarly, vaccination with alphavirus vectors expressing tumor antigens resulted in prophylactic protection against challenges with tumor-inducing cancerous cells. As certain alphaviruses, such as Chikungunya virus, have been associated with epidemics in animals and humans, attention has also been paid to the development of vaccines against alphaviruses themselves. Recent progress in alphavirus vector development and vaccine technology has allowed conducting clinical trials in humans.

  3. Constraint-based scheduling

    NASA Technical Reports Server (NTRS)

    Zweben, Monte

    1993-01-01

    The GERRY scheduling system developed by NASA Ames with assistance from the Lockheed Space Operations Company, and the Lockheed Artificial Intelligence Center, uses a method called constraint-based iterative repair. Using this technique, one encodes both hard rules and preference criteria into data structures called constraints. GERRY repeatedly attempts to improve schedules by seeking repairs for violated constraints. The system provides a general scheduling framework which is being tested on two NASA applications. The larger of the two is the Space Shuttle Ground Processing problem which entails the scheduling of all the inspection, repair, and maintenance tasks required to prepare the orbiter for flight. The other application involves power allocation for the NASA Ames wind tunnels. Here the system will be used to schedule wind tunnel tests with the goal of minimizing power costs. In this paper, we describe the GERRY system and its application to the Space Shuttle problem. We also speculate as to how the system would be used for manufacturing, transportation, and military problems.

  4. Nanowire-based detector

    DOEpatents

    Berggren, Karl K; Hu, Xiaolong; Masciarelli, Daniele

    2014-06-24

    Systems, articles, and methods are provided related to nanowire-based detectors, which can be used for light detection in, for example, single-photon detectors. In one aspect, a variety of detectors are provided, for example one including an electrically superconductive nanowire or nanowires constructed and arranged to interact with photons to produce a detectable signal. In another aspect, fabrication methods are provided, including techniques to precisely reproduce patterns in subsequently formed layers of material using a relatively small number of fabrication steps. By precisely reproducing patterns in multiple material layers, one can form electrically insulating materials and electrically conductive materials in shapes such that incoming photons are redirected toward a nearby electrically superconductive materials (e.g., electrically superconductive nanowire(s)). For example, one or more resonance structures (e.g., comprising an electrically insulating material), which can trap electromagnetic radiation within its boundaries, can be positioned proximate the nanowire(s). The resonance structure can include, at its boundaries, electrically conductive material positioned proximate the electrically superconductive nanowire such that light that would otherwise be transmitted through the sensor is redirected toward the nanowire(s) and detected. In addition, electrically conductive material can be positioned proximate the electrically superconductive nanowire (e.g. at the aperture of the resonant structure), such that light is directed by scattering from this structure into the nanowire.

  5. Acyl homoserine lactone-based quorum sensing stimulates biofilm formation by Salmonella Enteritidis in anaerobic conditions.

    PubMed

    Almeida, Felipe Alves de; Pimentel-Filho, Natan de Jesus; Pinto, Uelinton Manoel; Mantovani, Hilário Cuquetto; Oliveira, Leandro Licursi de; Vanetti, Maria Cristina Dantas

    2017-04-01

    Quorum sensing regulates a variety of phenotypes in bacteria including the production of virulence factors. Salmonella spp. have quorum sensing systems mediated by three autoinducers (AI-1, AI-2, and AI-3). The AI-1-mediated system is incomplete in that the bacterium relies on the synthesis of signaling molecules by other microorganisms. This study aimed to evaluate the influence of the AI-1 N-dodecanoyl-DL-homoserine lactone (C12-HSL) on the growth, motility, adhesion, and biofilm formation of Salmonella enterica serovar Enteritidis PT4 578 on a polystyrene surface. Experiments were conducted at 37 °C in anaerobic tryptone soy broth supplemented with C12-HSL and/or a mixture of four synthetic furanones, at the concentration of 50 nM each. The planktonic growth, adhesion, swarming, and twitching motility were not altered in the presence of C12-HSL and/or furanones under anaerobic conditions. However, C12-HSL induced biofilm formation after 36 h of cultivation as determined by quantification of biofilm formation, by enumeration of adhered cells to polystyrene coupons, and finally by imaging the presence of multilayered cells on an epifluorescence microscope. When furanones were present in the medium, an antagonistic effect against C12-HSL on the biofilm development was observed. The results demonstrate an induction of biofilm formation in Salmonella Enteritidis by AI-1 under anaerobic conditions. Considering that Salmonella does not produce AI-1 but respond to it, C12-HSL synthesized by other bacterial species could trigger biofilm formation by this pathogen in conditions that are relevant for its pathogenesis.

  6. Military Bases and Conservation Markets

    SciTech Connect

    Mark Ankeny

    2007-09-01

    Over time, DoD is likely to be one of the largest buyers and sellers in a water quality trading market. The Department of Defense (DoD) operates military bases that resemble small cities in infrastructure. As units redeploy, bases are likely to find themselves well within their environmental limits at the originating base and potentially bumping against limits such as nitrate and phosphate loading at the destination base. Stricter rules and heavier loadings in growing watersheds also present challenges to local bases and municipalities as regulators clamp down on loadings from existing Waste Water Treatment Plants (WWTPs) to meet water quality standards.

  7. Graphene based gene transfection

    NASA Astrophysics Data System (ADS)

    Feng, Liangzhu; Zhang, Shuai; Liu, Zhuang

    2011-03-01

    Graphene as a star in materials research has been attracting tremendous attentions in the past few years in various fields including biomedicine. In this work, for the first time we successfully use graphene as a non-toxic nano-vehicle for efficient gene transfection. Graphene oxide (GO) is bound with cationic polymers, polyethyleneimine (PEI) with two different molecular weights at 1.2 kDa and 10 kDa, forming GO-PEI-1.2k and GO-PEG-10k complexes, respectively, both of which are stable in physiological solutions. Cellular toxicity tests reveal that our GO-PEI-10k complex exhibits significantly reduced toxicity to the treated cells compared to the bare PEI-10k polymer. The positively charged GO-PEI complexes are able to further bind with plasmid DNA (pDNA) for intracellular transfection of the enhanced green fluorescence protein (EGFP) gene in HeLa cells. While EGFP transfection with PEI-1.2k appears to be ineffective, high EGFP expression is observed using the corresponding GO-PEI-1.2k as the transfection agent. On the other hand, GO-PEI-10k shows similar EGFP transfection efficiency but lower toxicity compared with PEI-10k. Our results suggest graphene to be a novel gene delivery nano-vector with low cytotoxicity and high transfection efficiency, promising for future applications in non-viral based gene therapy.Graphene as a star in materials research has been attracting tremendous attentions in the past few years in various fields including biomedicine. In this work, for the first time we successfully use graphene as a non-toxic nano-vehicle for efficient gene transfection. Graphene oxide (GO) is bound with cationic polymers, polyethyleneimine (PEI) with two different molecular weights at 1.2 kDa and 10 kDa, forming GO-PEI-1.2k and GO-PEG-10k complexes, respectively, both of which are stable in physiological solutions. Cellular toxicity tests reveal that our GO-PEI-10k complex exhibits significantly reduced toxicity to the treated cells compared to the bare PEI

  8. Measurement-based quantum communication

    NASA Astrophysics Data System (ADS)

    Zwerger, M.; Briegel, H. J.; Dür, W.

    2016-03-01

    We review and discuss the potential of using measurement-based elements in quantum communication schemes, where certain tasks are realized with the help of entangled resource states that are processed by measurements. We consider long-range quantum communication based on the transmission of encoded quantum states, where encoding, decoding and syndrome readout are implemented using small-scale resource states. We also discuss entanglement-based schemes and consider measurement-based quantum repeaters. An important element in these schemes is entanglement purification, which can also be implemented in a measurement-based way. We analyze the influence of noise and imperfections in these schemes and show that measurement-based implementation allows for very large error thresholds of the order of 10 % noise per qubit and more. We show how to obtain optimal resource states for different tasks and discuss first experimental realizations of measurement-based quantum error correction using trapped ions and photons.

  9. Carbon Nanotube Based Light Sensor

    NASA Technical Reports Server (NTRS)

    Wincheski, russell A. (Inventor); Smits, Jan M. (Inventor); Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Ingram, JoAnne L. (Inventor)

    2006-01-01

    A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

  10. Telemetry-Based Ranging

    NASA Technical Reports Server (NTRS)

    Hamkins, Jon; Vilnrotter, Victor A.; Andrews, Kenneth S.; Shambayati, Shervin

    2011-01-01

    A telemetry-based ranging scheme was developed in which the downlink ranging signal is eliminated, and the range is computed directly from the downlink telemetry signal. This is the first Deep Space Network (DSN) ranging technology that does not require the spacecraft to transmit a separate ranging signal. By contrast, the evolutionary ranging techniques used over the years by NASA missions, including sequential ranging (transmission of a sequence of sinusoids) and PN-ranging (transmission of a pseudo-noise sequence) whether regenerative (spacecraft acquires, then regenerates and retransmits a noise-free ranging signal) or transparent (spacecraft feeds the noisy demodulated uplink ranging signal into the downlink phase modulator) relied on spacecraft power and bandwidth to transmit an explicit ranging signal. The state of the art in ranging is described in an emerging CCSDS (Consultative Committee for Space Data Systems) standard, in which a pseudo-noise (PN) sequence is transmitted from the ground to the spacecraft, acquired onboard, and the PN sequence is coherently retransmitted back to the ground, where a delay measurement is made between the uplink and downlink signals. In this work, the telemetry signal is aligned with the uplink PN code epoch. The ground station computes the delay between the uplink signal transmission and the received downlink telemetry. Such a computation is feasible because symbol synchronizability is already an integral part of the telemetry design. Under existing technology, the telemetry signal cannot be used for ranging because its arrival-time information is not coherent with any Earth reference signal. By introducing this coherence, and performing joint telemetry detection and arrival-time estimation on the ground, a high-rate telemetry signal can provide all the precision necessary for spacecraft ranging.

  11. Soy-based renoprotection

    PubMed Central

    McGraw, Nancy J; Krul, Elaine S; Grunz-Borgmann, Elizabeth; Parrish, Alan R

    2016-01-01

    Chronic kidney disease (CKD) is a significant public health problem as risk factors such as advanced age, obesity, hypertension and diabetes rise in the global population. Currently there are no effective pharmacologic treatments for this disease. The role of diet is important for slowing the progression of CKD and managing symptoms in later stages of renal insufficiency. While low protein diets are generally recommended, maintaining adequate levels of intake is critical for health. There is an increasing appreciation that the source of protein may also be important. Soybean protein has been the most extensively studied plant-based protein in subjects with kidney disease and has demonstrated renal protective properties in a number of clinical studies. Soy protein consumption has been shown to slow the decline in estimated glomerular filtration rate and significantly improve proteinuria in diabetic and non-diabetic patients with nephropathy. Soy’s beneficial effects on renal function may also result from its impact on certain physiological risk factors for CKD such as dyslipidemia, hypertension and hyperglycemia. Soy intake is also associated with improvements in antioxidant status and systemic inflammation in early and late stage CKD patients. Studies conducted in animal models have helped to identify the underlying molecular mechanisms that may play a role in the positive effects of soy protein on renal parameters in polycystic kidney disease, metabolically-induced kidney dysfunction and age-associated progressive nephropathy. Despite the established relationship between soy and renoprotection, further studies are needed for a clear understanding of the role of the cellular and molecular target(s) of soy protein in maintaining renal function. PMID:27152261

  12. Velocity Based Modulus Calculations

    NASA Astrophysics Data System (ADS)

    Dickson, W. C.

    2007-12-01

    A new set of equations are derived for the modulus of elasticity E and the bulk modulus K which are dependent only upon the seismic wave propagation velocities Vp, Vs and the density ρ. The three elastic moduli, E (Young's modulus), the shear modulus μ (Lamé's second parameter) and the bulk modulus K are found to be simple functions of the density and wave propagation velocities within the material. The shear and elastic moduli are found to equal the density of the material multiplied by the square of their respective wave propagation-velocities. The bulk modulus may be calculated from the elastic modulus using Poisson's ratio. These equations and resultant values are consistent with published literature and values in both magnitude and dimension (N/m2) and are applicable to the solid, liquid and gaseous phases. A 3D modulus of elasticity model for the Parkfield segment of the San Andreas Fault is presented using data from the wavespeed model of Thurber et al. [2006]. A sharp modulus gradient is observed across the fault at seismic depths, confirming that "variation in material properties play a key role in fault segmentation and deformation style" [Eberhart-Phillips et al., 1993] [EPM93]. The three elastic moduli E, μ and K may now be calculated directly from seismic pressure and shear wave propagation velocities. These velocities may be determined using conventional seismic reflection, refraction or transmission data and techniques. These velocities may be used in turn to estimate the density. This allows velocity based modulus calculations to be used as a tool for geophysical analysis, modeling, engineering and prospecting.

  13. Lunar Base Heat Pump

    NASA Technical Reports Server (NTRS)

    Walker, D.; Fischbach, D.; Tetreault, R.

    1996-01-01

    The objective of this project was to investigate the feasibility of constructing a heat pump suitable for use as a heat rejection device in applications such as a lunar base. In this situation, direct heat rejection through the use of radiators is not possible at a temperature suitable for lde support systems. Initial analysis of a heat pump of this type called for a temperature lift of approximately 378 deg. K, which is considerably higher than is commonly called for in HVAC and refrigeration applications where heat pumps are most often employed. Also because of the variation of the rejection temperature (from 100 to 381 deg. K), extreme flexibility in the configuration and operation of the heat pump is required. A three-stage compression cycle using a refrigerant such as CFC-11 or HCFC-123 was formulated with operation possible with one, two or three stages of compression. Also, to meet the redundancy requirements, compression was divided up over multiple compressors in each stage. A control scheme was devised that allowed these multiple compressors to be operated as required so that the heat pump could perform with variable heat loads and rejection conditions. A prototype heat pump was designed and constructed to investigate the key elements of the high-lift heat pump concept. Control software was written and implemented in the prototype to allow fully automatic operation. The heat pump was capable of operation over a wide range of rejection temperatures and cooling loads, while maintaining cooling water temperature well within the required specification of 40 deg. C +/- 1.7 deg. C. This performance was verified through testing.

  14. Space-based detectors

    NASA Astrophysics Data System (ADS)

    Sesana, A.; Weber, W. J.; Killow, C. J.; Perreur-Lloyd, M.; Robertson, D. I.; Ward, H.; Fitzsimons, E. D.; Bryant, J.; Cruise, A. M.; Dixon, G.; Hoyland, D.; Smith, D.; Bogenstahl, J.; McNamara, P. W.; Gerndt, R.; Flatscher, R.; Hechenblaikner, G.; Hewitson, M.; Gerberding, O.; Barke, S.; Brause, N.; Bykov, I.; Danzmann, K.; Enggaard, A.; Gianolio, A.; Vendt Hansen, T.; Heinzel, G.; Hornstrup, A.; Jennrich, O.; Kullmann, J.; Møller-Pedersen, S.; Rasmussen, T.; Reiche, J.; Sodnik, Z.; Suess, M.; Armano, M.; Sumner, T.; Bender, P. L.; Akutsu, T.; Sathyaprakash, B. S.

    2014-12-01

    The parallel session C5 on Space-Based Detectors gave a broad overview over the planned space missions related to gravitational wave detection. Overviews of the revolutionary science to be expected from LISA was given by Alberto Sesana and Sasha Buchman. The launch of LISA Pathfinder (LPF) is planned for 2015. This mission and its payload "LISA Technology Package" will demonstrate key technologies for LISA. In this context, reference masses in free fall for LISA, and gravitational physics in general, was described by William Weber, laser interferometry at the pico-metre level and the optical bench of LPF was presented by Christian Killow and the performance of the LPF optical metrology system by Paul McNamara. While LPF will not yet be sensitive to gravitational waves, it may nevertheless be used to explore fundamental physics questions, which was discussed by Michele Armano. Some parts of the LISA technology that are not going to be demonstrated by LPF, but under intensive development at the moment, were presented by Oliver Jennrich and Oliver Gerberding. Looking into the future, Japan is studying the design of a mid-frequency detector called DECIGO, which was discussed by Tomotada Akutsu. Using atom interferometry for gravitational wave detection has also been recently proposed, and it was critically reviewed by Peter Bender. In the nearer future, the launch of GRACE Follow-On (for Earth gravity observation) is scheduled for 2017, and it will include a Laser Ranging Interferometer as technology demonstrator. This will be the first inter-spacecraft laser interferometer and has many aspects in common with the LISA long arm, as discussed by Andrew Sutton.

  15. Ferrocene-Based Nanoelectronics

    SciTech Connect

    Lawrence R. Sita

    2006-02-15

    Ferrocene-based molecular components for nanoelectronics offer a number of distinct advantages relative to all carbon frameworks due to metal-centered molecular states that should be closer in energy to the Fermi levels of the metal electrodes in metal / molecule / metal heterojunctions. Given this, the overall goal of the project was to investigate the conduction physics of a variety of proposed ferrocene diode / transistor designs in order to address the fundamental question; can electron transport within nm-length scale structures be modulated in a controlled fashion? During the funded period, substantial progress towards achieving this goal was made by surmounting a number of scientific and technical obstacles. More specifically, a concise and general synthetic route to several mono- and diferrocene dithiols and monothiols was achieved that now allows for the directed and controlled assembly of a variety of metal / molecule /metal test structures for the single molecule conductance measurements and the fabrication of self-assembled monolayers (SAMs) on Au(111) that are amenable to quantitative electrochemical characterization of electron-transfer rates. Most importantly, by using an electromigrated test structure, reproducible I/V data for one of the ferrocene dithiol molecules have been collected which exhibit surprisingly high conductance. Exceptional agreement of this result with theory serves to substantiate the original hypothesis that metal-centered states within a molecular bridge can indeed serve to establish higher conductance relative to all-organic molecular bridges. Overall, the successful demonstration of the ability of ferrocene-molecular frameworks to serve as exceptional molecular conductors will play an important role in the continued evolution in design of molecular components for nanoelectronic devices, which in turn, will have a positive impact on the science and potential technologies associated with these systems.

  16. Case-based reasoning: The marriage of knowledge base and data base

    NASA Technical Reports Server (NTRS)

    Pulaski, Kirt; Casadaban, Cyprian

    1988-01-01

    The coupling of data and knowledge has a synergistic effect when building an intelligent data base. The goal is to integrate the data and knowledge almost to the point of indistinguishability, permitting them to be used interchangeably. Examples given in this paper suggest that Case-Based Reasoning is a more integrated way to link data and knowledge than pure rule-based reasoning.

  17. Chemorepulsion from the Quorum Signal Autoinducer-2 Promotes Helicobacter pylori Biofilm Dispersal

    PubMed Central

    Anderson, Jeneva K.; Huang, Julie Y.; Wreden, Christopher; Sweeney, Emily Goers; Goers, John; Remington, S. James

    2015-01-01

    ABSTRACT The gastric pathogen Helicobacter pylori forms biofilms on abiotic and biotic surfaces. We have shown previously that H. pylori perceives the quorum signal autoinducer-2 (AI-2) as a chemorepellent. We report here that H. pylori chemorepulsion from endogenous AI-2 influences the proportions and spatial organization of cells within biofilms. Strains that fail to produce AI-2 (∆luxS strains) or are defective for chemotaxis (∆cheA strains) formed more spatially homogenous biofilms with a greater proportion of adherent versus planktonic cells than wild-type biofilms. Reciprocally, a strain that overproduced AI-2 (luxSOP) formed biofilms with proportionally fewer adherent cells. Along with the known AI-2 chemoreceptor, TlpB, we identified AibA and AibB, two novel periplasmic binding proteins that are required for the AI-2 chemorepulsion response. Disruptions in any of the proteins required for AI-2 chemotaxis recapitulated the biofilm adherence and spatial organization phenotype of the ∆luxS mutant. Furthermore, exogenous administration of AI-2 was sufficient to decrease the proportion of adherent cells in biofilms and promote dispersal of cells from biofilms in a chemotaxis-dependent manner. Finally, we found that disruption of AI-2 production or AI-2 chemotaxis resulted in increased clustering of cells in microcolonies on cultured epithelial cells. We conclude that chemotaxis from AI-2 is a determinant of H. pylori biofilm spatial organization and dispersal. PMID:26152582

  18. XML-Based SHINE Knowledge Base Interchange Language

    NASA Technical Reports Server (NTRS)

    James, Mark; Mackey, Ryan; Tikidjian, Raffi

    2008-01-01

    The SHINE Knowledge Base Interchange Language software has been designed to more efficiently send new knowledge bases to spacecraft that have been embedded with the Spacecraft Health Inference Engine (SHINE) tool. The intention of the behavioral model is to capture most of the information generally associated with a spacecraft functional model, while specifically addressing the needs of execution within SHINE and Livingstone. As such, it has some constructs that are based on one or the other.

  19. Base pairing and base mis-pairing in nucleic acids

    NASA Technical Reports Server (NTRS)

    Wang, A. H. J.; Rich, A.

    1986-01-01

    In recent years we have learned that DNA is conformationally active. It can exist in a number of different stable conformations including both right-handed and left-handed forms. Using single crystal X-ray diffraction analysis we are able to discover not only additional conformations of the nucleic acids but also different types of hydrogen bonded base-base interactions. Although Watson-Crick base pairings are the predominant type of interaction in double helical DNA, they are not the only types. Recently, we have been able to examine mismatching of guanine-thymine base pairs in left-handed Z-DNA at atomic resolution (1A). A minimum amount of distortion of the sugar phosphate backbone is found in the G x T pairing in which the bases are held together by two hydrogen bonds in the wobble pairing interaction. Because of the high resolution of the analysis we can visualize water molecules which fill in to accommodate the other hydrogen bonding positions in the bases which are not used in the base-base interactions. Studies on other DNA oligomers have revealed that other types of non-Watson-Crick hydrogen bonding interactions can occur. In the structure of a DNA octamer with the sequence d(GCGTACGC) complexed to an antibiotic triostin A, it was found that the two central AT base pairs are held together by Hoogsteen rather than Watson-Crick base pairs. Similarly, the G x C base pairs at the ends are also Hoogsteen rather than Watson-Crick pairing. Hoogsteen base pairs make a modified helix which is distinct from the Watson-Crick double helix.

  20. RT-PCR-based evidence for the in vivo stimulation of renal tubularp-aminohippurate (PAH) transport by triiodothyronine (T3) or dexamethasone (DEXA) in kidney tissue of immature and adult rats.

    PubMed

    Bahn, Andrew; Hauss, Achim; Appenroth, Dorothea; Ebbinghaus, Diana; Hagos, Yohannes; Steinmetzer, Peter; Burckhardt, Gerhard; Fleck, Christian

    2003-06-01

    Our previous studies have shown that a pre-treatment of rats with triiodothyronine (T3) or dexamethasone (DEXA) increases renal PAH excretion significantly. This stimulation was accompanied by an enhanced protein synthesis within the renal cortex. To explore the molecular basis for this sub-chronic induction process, we investigated the stimulation of PAH accumulation in renal cortical slices as well as the expression level of organic anion transporter 1 (OAT1), the recently cloned renal basolateral PAH-transporter, using RT-PCR techniques under the applied conditions. 10- and 55-day-old Han:WIST rats were treated in vivo with T3 (20 microg/100 g b.wt.) or DEXA (60 microg/100 g b.wt.), both for 3 days, once daily. Renal cortical slices were incubated for 2 hours in Cross-Taggart medium and PAH uptake into kidney tissue was measured time dependently (slice to medium ratio, QS/M). The accumulation capacity is comparable between immature and mature rats (control-QS/M: 6.7 +/- 0.1 vs. 6.9 +/- 0.2, respectively). Both age groups showed a significant increase of PAH accumulation capacity after T3 treatment (10-day-old rats: 15.0 +/- 0.2; 55-day-old rats: 11.7 +/- 1.3). After DEXA pre-treatment, PAH accumulation was only slightly changed (10-day-old rats: 5.9 +/- 0.2; 55-day-old rats: 8.2 +/- 1.3). Semi-quantitative measurements of OAT1 mRNA expression level showed a significant increase of OAT1 mRNA after pre-treatment with both T3 and DEXA in the two age groups. Thus, this is the first evidence that T3 and DEXA pre-treatment induces the expression of OAT1.